What is the mechanism of inflammatory response and pathogenesis of COVID-19 cases?

The inflammatory response to SARS-coronavirus-2 (SARS-CoV-2) infection is thought to underpin COVID-19 pathogenesis We conducted daily transcriptomic profiling of three COVID-19 cases and found that the early immune response in COVID-19 patients is highly dynamic Patient throat swabs were tested daily for SARS-CoV-2 with the virus persisting for 3-4 weeks in all three patients Cytokine analyses of whole blood revealed increased cytokine expression in the single more severe case However, most inflammatory gene expression peaked after respiratory function nadir, except those in the IL1 pathway Parallel analyses of CD4 and CD8 expression suggested that the pro-inflammatory response may be intertwined with T-cell activation that could exacerbate disease or prolong the infection Collectively, these findings hint at the possibility that IL1 and related pro-inflammatory pathways may be prognostic and serve as therapeutic targets for COVID-19 This work may also guide future studies to illuminate COVID-19 pathogenesis and develop host-directed therapies

A dynamic immune response shapes COVID-19 progression

The inflammatory response to SARS-coronavirus-2 (SARS-CoV-2) infection is thought to underpin COVID-19 pathogenesis. We conducted daily transcriptomic profiling of three COVID-19 cases and found that the early immune response in COVID-19 patients is highly dynamic. Patient throat swabs were tested daily for SARS-CoV-2, with the virus persisting for 3 to 4 weeks in all three patients. Cytokine analyses of whole blood revealed increased cytokine expression in the single most severe case. However, most inflammatory gene expression peaked after respiratory function nadir, except expression in the IL1 pathway. Parallel analyses of CD4 and CD8 expression suggested that the pro-inflammatory response may be intertwined with T cell activation that could exacerbate disease or prolong the infection. Collectively, these findings hint at the possibility that IL1 and related pro-inflammatory pathways may be prognostic and serve as therapeutic targets for COVID-19. This work may also guide future studies to illuminate COVID-19 pathogenesis and develop host-directed therapies.

A Dynamic Immune Response Shapes COVID-19 Progression

IMPACT STATEMENT: In late 2019, a novel virus called SARS-CoV-2, expanded globally from Wuhan, China and was declared a pandemic on 11 March 2020 by the WHO. The mechanism of virus entry inside the host cell depends upon the cellular proteases including cathepsins, HAT, and TMPRSS2, which splits up the spike protein and causes further penetration. MERS coronavirus uses DPP4, while coronavirus HCoV-NL63 and SARS-CoV and SARS-CoV-2 employ ACE-2 as the key receptor. Cytokine storm syndrome was analyzed in critically ill nCOVID-19 patients and it is presented with high inflammatory mediators, systemic inflammation, and multiple organ failure. Among various inflammatory mediators, the level of interleukins (IL-2, IL-7, IL-10), G-CSF, MIP1A, MCP1, and TNF-α was reported to be higher in critically ill patients. Understanding this molecular mechanism of ILs, T cells, and dendritic cells will be helpful to design immunotherapy and novel drugs for the treatment of nCOVID-19 infection.

Role of inflammatory markers in corona virus disease (COVID-19) patients: A review

The COVID-19 pandemic caused by infection with SARS-CoV-2 has led to more than 200,000 deaths worldwide. Several studies have now established that the hyperinflammatory response induced by SARS-CoV-2 is a major cause of disease severity and death in infected patients. Macrophages are a population of innate immune cells that sense and respond to microbial threats by producing inflammatory molecules that eliminate pathogens and promote tissue repair. However, a dysregulated macrophage response can be damaging to the host, as is seen in the macrophage activation syndrome induced by severe infections, including in infections with the related virus SARS-CoV. Here we describe the potentially pathological roles of macrophages during SARS-CoV-2 infection and discuss ongoing and prospective therapeutic strategies to modulate macrophage activation in patients with COVID-19.

Pathological inflammation in patients with COVID-19: a key role for monocytes and macrophages

IMPACT STATEMENT In late 2019, a novel virus called SARS-CoV-2, expanded globally from Wuhan, China and was declared a pandemic on 11 March 2020 by the WHO. The mechanism of virus entry inside the host cell depends upon the cellular proteases including cathepsins, HAT, and TMPRSS2, which splits up the spike protein and causes further penetration. MERS coronavirus uses DPP4, while coronavirus HCoV-NL63 and SARS-CoV and SARS-CoV-2 employ ACE-2 as the key receptor. Cytokine storm syndrome was analyzed in critically ill nCOVID-19 patients and it is presented with high inflammatory mediators, systemic inflammation, and multiple organ failure. Among various inflammatory mediators, the level of interleukins (IL-2, IL-7, IL-10), G-CSF, MIP1A, MCP1, and TNF-α was reported to be higher in critically ill patients. Understanding this molecular mechanism of ILs, T cells, and dendritic cells will be helpful to design immunotherapy and novel drugs for the treatment of nCOVID-19 infection.

Role of inflammatory markers in corona virus disease (COVID-19) patients: A review.

The current COVID-19 pandemic began in December 2019 in Wuhan (China) and rapidly extended to become a global sanitary and economic emergency. Its etiological agent is the coronavirus SARS-CoV-2. COVID-19 presents a wide spectrum of clinical manifestations, which ranges from an asymptomatic infection to a severe pneumonia accompanied by multisystemic failure that can lead to a patient's death. The immune response to SARS-CoV-2 is known to involve all the components of the immune system that together appear responsible for viral elimination and recovery from the infection. Nonetheless, such immune responses are implicated in the disease's progression to a more severe and lethal process. This review describes the general aspects of both COVID-19 and its etiological agent SARS-CoV-2, stressing the similarities with other severe coronavirus infections, such as SARS and MERS, but more importantly, pointing toward the evidence supporting the hypothesis that the clinical spectrum of COVID-19 is a consequence of the corresponding variable spectrum of the immune responses to the virus. The critical point where progression of the disease ensues appears to center on loss of the immune regulation between protective and altered responses due to exacerbation of the inflammatory components. Finally, it appears possible to delineate certain major challenges deserving of exhaustive investigation to further understand COVID-19 immunopathogenesis, thus helping to design more effective diagnostic, therapeutic, and prophylactic strategies.

Immune Response, Inflammation, and the Clinical Spectrum of COVID-19

Currently, we are on a global pandemic of Coronavirus disease-2019 (COVID-19) which causes fever, dry cough, fatigue and acute respiratory distress syndrome (ARDS) that may ultimately lead to the death of the infected. Current researches on COVID-19 continue to highlight the necessity for further understanding the virus-host synergies. In this study, we have highlighted the key cytokines induced by coronavirus infections. We have demonstrated that genes coding interleukins (Il-1α, Il-1ß, Il-6, Il-10), chemokine (Ccl2, Ccl3, Ccl5, Ccl10), and interferon (Ifn-α2, Ifn-ß1, Ifn2) upsurge significantly which in line with the elevated infiltration of T cells, NK cells and monocytes in SARS-Cov treated group at 24 hours. Also, interleukins (IL-6, IL-23α, IL-10, IL-7, IL-1α, IL-1ß) and interferon (IFN-α2, IFN2, IFN-Î³) have increased dramatically in MERS-Cov at 24 hours. A similar cytokine profile showed the cytokine storm served a critical role in the infection process. Subsequent investigation of 463 patients with COVID-19 disease revealed the decreased amount of total lymphocytes, CD3+, CD4+, and CD8+ T lymphocytes in the severe type patients which indicated COVID-19 can impose hard blows on human lymphocyte resulting in lethal pneumonia. Thus, taking control of changes in immune factors could be critical in the treatment of COVID-19.

Immune environment modulation in pneumonia patients caused by coronavirus: SARS-CoV, MERS-CoV and SARS-CoV-2

Although most SARS-CoV-2-infected individuals experience mild coronavirus disease 2019 (COVID-19), some patients suffer from severe COVID-19, which is accompanied by acute respiratory distress syndrome and systemic inflammation. To identify factors driving severe progression of COVID-19, we performed single-cell RNA-seq using peripheral blood mononuclear cells (PBMCs) obtained from healthy donors, patients with mild or severe COVID-19, and patients with severe influenza. Patients with COVID-19 exhibited hyper-inflammatory signatures across all types of cells among PBMCs, particularly up-regulation of the TNF/IL-1ß-driven inflammatory response as compared to severe influenza. In classical monocytes from patients with severe COVID-19, type I IFN response co-existed with the TNF/IL-1ß-driven inflammation, and this was not seen in patients with milder COVID-19. Interestingly, we documented type I IFN-driven inflammatory features in patients with severe influenza as well. Based on this, we propose that the type I IFN response plays a pivotal role in exacerbating inflammation in severe COVID-19.

Immunophenotyping of COVID-19 and influenza highlights the role of type I interferons in development of severe COVID-19

The novel Coronavirus Disease 2019 (COVID-19), that began in Wuhan Province, China was labelled as an International Public Health Emergency on January 30, 2020 and later was declared a pandemic by the World Health Organisation (WHO) on March 11, 2020. The causative agent, SARS-CoV-2 was the third coronavirus responsible for causing major disease outbreaks in human population after Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) caused by SARS-CoV and MERS-CoV respectively. The patients of COVID-19 present with a clinical feature resembling mild form of viral pneumonia which in certain cases progress to a severe form characterised by adult respiratory distress syndrome (ARDS) and/or multiorgan failure leading to death. The transition from mild to severe form of COVID-19 is affected by a lot of factors like age, co-morbidities etc. In the absence of an absolute cure, it is essential to explore the molecular pathogenesis of the disease to identify people at risk of developing severity so that alternative treatment modalities may be planned. The aim of this review is to provide an update on the general characteristics of SARS-CoV-2 and highlight the inflammatory changes and immune dysregulation that may help in identification of molecular predictors of disease severity.

Inflammation, Immunity and Immunogenetics in COVID-19: A Narrative Review

Coronavirus Disease 2019 (COVID-19) has sparked a global pandemic, affecting more than 4 million people worldwide. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause acute lung injury (ALI) and even acute respiratory distress syndrome (ARDS); with a fatality of 7.0 %. Accumulating evidence suggested that the progression of COVID-19 is associated with lymphopenia and excessive inflammation, and a subset of severe cases might exhibit cytokine storm triggered by secondary hemophagocytic lymphohistiocytosis (sHLH). Furthermore, secondary bacterial infection may contribute to the exacerbation of COVID-19. We recommend using both IL-10 and IL-6 as the indicators of cytokine storm, and monitoring the elevation of procalcitonin (PCT) as an alert for initiating antibacterial agents. Understanding the dynamic progression of SARS-CoV-2 infection is crucial to determine an effective treatment strategy to reduce the rising mortality of this global pandemic.

Biochemical indicators of coronavirus disease 2019 exacerbation and the clinical implications

Although most SARS-CoV-2-infected individuals experience mild coronavirus disease 2019 (COVID-19), some patients suffer from severe COVID-19, which is accompanied by acute respiratory distress syndrome and systemic inflammation. To identify factors driving severe progression of COVID-19, we performed single-cell RNA-seq using peripheral blood mononuclear cells (PBMCs) obtained from healthy donors, patients with mild or severe COVID-19, and patients with severe influenza. Patients with COVID-19 exhibited hyper-inflammatory signatures across all types of cells among PBMCs, particularly up-regulation of the TNF/IL-1β-driven inflammatory response as compared to severe influenza. In classical monocytes from patients with severe COVID-19, type I IFN response co-existed with the TNF/IL-1β-driven inflammation, and this was not seen in patients with milder COVID-19. Interestingly, we documented type I IFN-driven inflammatory features in patients with severe influenza as well. Based on this, we propose that the type I IFN response plays a pivotal role in exacerbating inflammation in severe COVID-19.

Immunophenotyping of COVID-19 and influenza highlights the role of type I interferons in development of severe COVID-19.

Increasing evidence points to host Th17 inflammatory responses as contributing to the severe lung pathology and mortality of lower respiratory tract infections from coronaviruses. This includes host inflammatory and cytokine responses to COVID-19 caused by the SARS-2 coronavirus (SARS CoV2). From studies conducted in laboratory animals, there are additional concerns about immune enhancement and the role of potential host immunopathology resulting from experimental human COVID-19 vaccines. Here we summarize evidence suggesting there may be partial overlap between the underlying immunopathologic processes linked to both coronavirus infection and vaccination, and a role for Th17 in immune enhancement and eosinophilic pulmonary immunopathology. Such findings help explain the link between viral-vectored coronavirus vaccines and immune enhancement and its reduction through alum adjuvants. Additional research may also clarify links between COVID-19 pulmonary immunopathology and heart disease.

The potential role of Th17 immune responses in coronavirus immunopathology and vaccine-induced immune enhancement

Summary The outbreaks of 2019 novel coronavirus disease (COVID-19) caused by SARS-CoV-2 infection has posed a severe threat to global public health. It is unclear how the human immune system responds to this infection. Here, we used metatranscriptomic sequencing to profile immune signatures in the bronchoalveolar lavage fluid of eight COVID-19 cases. The expression of proinflammatory genes, especially chemokines, was markedly elevated in COVID-19 cases compared to community-acquired pneumonia patients and healthy controls, suggesting that SARS-CoV-2 infection causes hypercytokinemia. Compared to SARS-CoV, which is thought to induce inadequate interferon (IFN) responses, SARS-CoV-2 robustly triggered expression of numerous IFN-inducible genes (ISGs). These ISGs exhibit immunopathogenic potential, with overrepresentation of genes involved in inflammation. The transcriptome data was also used to estimate immune cell populations, revealing increases in activated dendritic cells and neutrophils. Collectively, these host responses to SARS-CoV-2 infection could further our understanding of disease pathogenesis and point towards antiviral strategies.

Heightened innate immune responses in the respiratory tract of COVID-19 patients

The outbreaks of 2019 novel coronavirus disease (COVID-19) caused by SARS-CoV-2 infection have posed a severe threat to global public health. It is unclear how the human immune system responds to this infection. Here, we used metatranscriptomic sequencing to profile immune signatures in the bronchoalveolar lavage fluid of eight COVID-19 cases. The expression of proinflammatory genes, especially chemokines, was markedly elevated in COVID-19 cases compared to community-acquired pneumonia patients and healthy controls, suggesting that SARS-CoV-2 infection causes hypercytokinemia. Compared to SARS-CoV, which is thought to induce inadequate interferon (IFN) responses, SARS-CoV-2 robustly triggered expression of numerous IFN-stimulated genes (ISGs). These ISGs exhibit immunopathogenic potential, with overrepresentation of genes involved in inflammation. The transcriptome data was also used to estimate immune cell populations, revealing increases in activated dendritic cells and neutrophils. Collectively, these host responses to SARS-CoV-2 infection could further our understanding of disease pathogenesis and point toward antiviral strategies.

Heightened Innate Immune Responses in the Respiratory Tract of COVID-19 Patients

Pathogenic human coronavirus infections, such as severe acute respiratory syndrome CoV (SARS-CoV) and Middle East respiratory syndrome CoV (MERS-CoV), cause high morbidity and mortality 1,2. Recently, a severe pneumonia-associated respiratory syndrome caused by a new coronavirus was reported at December 2019 (2019-nCoV) in the city Wuhan, Hubei province, China3–5, which was also named as pneumonia-associated respiratory syndrome (PARS)6. Up to 9th of February 2020, at least 37, 251 cases have been reported with 812 fatal cases according to the report from China CDC. However, the immune mechanism that potential orchestrated acute mortality from patients of 2019-nCoV is still unknown. Here we show that after the 2019-nCoV infection, CD4+T lymphocytes are rapidly activated to become pathogenic T helper (Th) 1 cells and generate GM-CSF etc. The cytokines environment induces inflammatory CD14+CD16+ monocytes with high expression of IL-6 and accelerates the inflammation. These aberrant and excessive immune cells may enter the pulmonary circulation in huge numbers and play an immune damaging role to causing lung functional disability and quick mortality. Our results demonstrate that excessive non-effective host immune responses by pathogenic T cells and inflammatory monocytes may associate with severe lung pathology. Therefore, we suggest that monoclonal antibody that targets the GM-CSF or interleukin 6 receptor may potentially curb immunopathology caused by 2019-nCoV and consequently win more time for virus clearance.

Aberrant pathogenic GM-CSF+ T cells and inflammatory CD14+CD16+ monocytes in severe pulmonary syndrome patients of a new coronavirus

Currently there is no effective antiviral therapy for SARS-CoV-2 infection, which frequently leads to fatal inflammatory responses and acute lung injury. Here, we discuss the various mechanisms of SARS-CoV-mediated inflammation. We also assume that SARS-CoV-2 likely shares similar inflammatory responses. Potential therapeutic tools to reduce SARS-CoV-2-induced inflammatory responses include various methods to block FcR activation. In the absence of a proven clinical FcR blocker, the use of intravenous immunoglobulin to block FcR activation may be a viable option for the urgent treatment of pulmonary inflammation to prevent severe lung injury. Such treatment may also be combined with systemic anti-inflammatory drugs or corticosteroids. However, these strategies, as proposed here, remain to be clinically tested for effectiveness.

Understanding SARS-CoV-2-Mediated Inflammatory Responses: From Mechanisms to Potential Therapeutic Tools

The novel coronavirus disease 2019 has rapidly increased in pandemic scale since it first appeared in Wuhan, China, in December 2019. In these troubled days the scientific community is asking for rapid replies to prevent and combat the emergency. It is generally accepted that only achieving a better understanding of the interactions between the virus and the host immune response and of the pathogenesis of infection is crucial to identify valid therapeutic tools to control virus entry, replication, and spread as well as to impair its lethal effects. On the basis of recent research progress of severe acute respiratory syndrome coronavirus 2 and the results on previous coronaviruses, in this contribution we underscore some of the main unsolved problems, mostly focusing on pathogenetic aspects and host immunity to the virus. On this basis, we also touch important aspects regarding the immune response in asymptomatic subjects, the immune evasion of severe acute respiratory syndrome coronavirus 2 in severe patients, and differences in disease severity by age and sex.

COVID-19: Unanswered questions on immune response and pathogenesis

Abstract Increasing evidence points to host Th17 inflammatory responses as contributing to the severe lung pathology and mortality of lower respiratory tract infections from coronaviruses. This includes host inflammatory and cytokine responses to COVID-19 caused by the SARS-2 coronavirus (SARS CoV2). From studies conducted in laboratory animals, there are additional concerns about immune enhancement and the role of potential host immunopathology resulting from experimental human COVID-19 vaccines. Here we summarize evidence suggesting there may be partial overlap between the underlying immunopathologic processes linked to both coronavirus infection and vaccination, and a role for Th17 in immune enhancement and eosinophilic pulmonary immunopathology. Such findings help explain the link between viral-vectored coronavirus vaccines and immune enhancement and its reduction through alum adjuvants. Additional research may also clarify links between COVID-19 pulmonary immunopathology and heart disease.

The Potential Role of Th17 Immune Responses in Coronavirus Immunopathology and Vaccine-induced Immune Enhancement

BACKGROUND AND AIMS: The outbreak of the new coronavirus, SARS-CoV-2, causes a respiratory disease and individuals with pre-existing cardiometabolic disorders display worse prognosis through the infection course. The aim of this minireview is to present epidemiological data related to metabolic comorbidities in association with the SARS-CoV-2. METHODS: This is a narrative mini-review with Pubmed search until April 23, 2020 using the keywords COVID-19, SARS-CoV-2, treatment of coronavirus and following terms: diabetes mellitus, obesity, arterial hypertension, ACE-inhibitors, cytokine storm, immune response and vitamin D. RESULTS: Studies indicate that obese individuals are more likely to develop infections, and that adipose tissue serves as a pathogen reservoir. In diabetic individuals higher rate of inflammatory processes is seen due to constant glucose recognition by C type lectin receptors. Hypertensive individuals, usually grouped with other conditions, are treated with drugs to reduce blood pressure mostly through ACEi and ARB, that leads to increased ACE2 expression, used by SARS-CoV-2 for human's cell entry. Until now, the studies have shown that individuals with those conditions and affected by COVID-19 present an uncontrolled release of pro-inflammatory cytokines and an unbalanced immune response, leading to the cytokine storm phenomenon. Vitamin D is highlighted as a potential therapeutic target, because in addition to acting on the immune system, it plays an important role in the control of cardiometabolic diseases. CONCLUSION: Currently, since there is no proven and effective antiviral therapy for SARS-CoV-2, the efforts should focus on controlling inflammatory response and reduce the risks of associated complications.

Mechanism of inflammatory response in associated comorbidities in COVID-19

Clinical evidence indicates that the fatal outcome observed with severe acute respiratory syndrome-coronavirus-2 infection often results from alveolar injury that impedes airway capacity and multi-organ failure-both of which are associated with the hyperproduction of cytokines, also known as a cytokine storm or cytokine release syndrome. Clinical reports show that both mild and severe forms of disease result in changes in circulating leukocyte subsets and cytokine secretion, particularly IL-6, IL-1ß, IL-10, TNF, GM-CSF, IP-10 (IFN-induced protein 10), IL-17, MCP-3, and IL-1ra. Not surprising, therapies that target the immune response and curtail the cytokine storm in coronavirus 2019 (COVID-19) patients have become a focus of recent clinical trials. Here we review reports on leukocyte and cytokine data associated with COVID-19 disease in 3939 patients in China and describe emerging data on immunopathology. With an emphasis on immune modulation, we also look at ongoing clinical studies aimed at blocking proinflammatory cytokines; transfer of immunosuppressive mesenchymal stem cells; use of convalescent plasma transfusion; as well as immunoregulatory therapy and traditional Chinese medicine regimes. In examining leukocyte and cytokine activity in COVID-19, we focus in particular on how these levels are altered as the disease progresses (neutrophil NETosis, macrophage, T cell response, etc.) and proposed consequences to organ pathology (coagulopathy, etc.). Viral and host interactions are described to gain further insight into leukocyte biology and how dysregulated cytokine responses lead to disease and/or organ damage. By better understanding the mechanisms that drive the intensity of a cytokine storm, we can tailor treatment strategies at specific disease stages and improve our response to this worldwide public health threat.

Cytokine storm and leukocyte changes in mild versus severe SARS-CoV-2 infection: Review of 3939 COVID-19 patients in China and emerging pathogenesis and therapy concepts

We demonstrate that the general clinical conditions, risk factors and numerous pathological and biological features of COVID-19 are analogous with various disorders caused by the uncontrolled formation of neutrophil extracellular traps and their by-products. Given the rapid evolution of this disease's symptoms and its lethality, we hypothesize that SARS-CoV2 evades innate immune response causing COVID-19 progresses under just such an amplifier loop, leading to a massive, uncontrolled inflammation process. This work allows us to propose new strategies for treating the pandemic.

SARS-CoV2 may evade innate immune response, causing uncontrolled neutrophil extracellular traps formation and multi-organ failure.

Pathogenic human coronavirus infections, such as severe acute respiratory syndrome CoV (SARS-CoV) and Middle East respiratory syndrome CoV (MERS-CoV), cause high morbidity and mortality1, 2 Recently, a severe pneumonia-associated respiratory syndrome caused by a new coronavirus (SARS-CoV-2) was reported at December 2019 in the city Wuhan, Hubei province, China3, 4, 5, which was also named as pneumonia-associated respiratory syndrome (PARS)6 and can cause coronavirus disease 2019 (COVID-19) to seriously endanger human health Up to 24th of February 2020, at least 77779 cases have been reported with 2666 fatal cases according to the report from China CDC However, the immune mechanism that potential orchestrated acute mortality from COVID-19 patients is still unknown Here we show that after the SARS-CoV-2 infection, CD4+ T lymphocytes are rapidly activated to become pathogenic T helper (Th) 1 cells and generate GM-CSF etc The cytokines environment induces inflammatory CD14+CD16+ monocytes with high expression of IL-6 and accelerate the inflammation Given that large amount of inflammatory cells infiltrations have been observed in lungs from severe COVID-19 patients7, 8, these aberrant pathogenic Th1 cells and inflammatory monocytes may enter the pulmonary circulation in huge numbers and play an immune damaging role to causing lung functional disability and quick mortality Our results demonstrate that excessive non-effective host immune responses by pathogenic T cells and inflammatory monocytes may associate with severe lung pathology Thus, we suggest that monoclonal antibodies targeting GM-CSF or interleukin 6 may be effective in blocking inflammatory storms and, therefore, be a promising treatment of severe COVID-19 patients

Pathogenic T cells and inflammatory monocytes incite inflammatory storm in severe COVID-19 patients

Currently, we are on a global pandemic of Coronavirus disease-2019 (COVID-19) which causes fever, dry cough, fatigue and acute respiratory distress syndrome (ARDS) that may ultimately lead to the death of the infected. Current researches on COVID-19 continue to highlight the necessity for further understanding the virus-host synergies. In this study, we have highlighted the key cytokines induced by coronavirus infections. We have demonstrated that genes coding interleukins (Il-1α, Il-1β, Il-6, Il-10), chemokine (Ccl2, Ccl3, Ccl5, Ccl10), and interferon (Ifn-α2, Ifn-β1, Ifn2) upsurge significantly which in line with the elevated infiltration of T cells, NK cells and monocytes in SARS-Cov treated group at 24 hours. Also, interleukins (IL-6, IL-23α, IL-10, IL-7, IL-1α, IL-1β) and interferon (IFN-α2, IFN2, IFN-γ) have increased dramatically in MERS-Cov at 24 hours. A similar cytokine profile showed the cytokine storm served a critical role in the infection process. Subsequent investigation of 463 patients with COVID-19 disease revealed the decreased amount of total lymphocytes, CD3+, CD4+, and CD8+ T lymphocytes in the severe type patients which indicated COVID-19 can impose hard blows on human lymphocyte resulting in lethal pneumonia. Thus, taking control of changes in immune factors could be critical in the treatment of COVID-19.

Coronavirus disease 2019 (COVID-19), caused by an outbreak of the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) in Wuhan, China, has led to an unprecedented health and economic crisis worldwide. To develop treatments that can stop or lessen the symptoms and severity of SARS-CoV-2 infection, it is critical to understand how the virus behaves inside human cells, and so far studies in this area remain scarce. A recent study investigated translatome and proteome host cell changes induced in vitro by SARS-CoV-2. Here, we use the publicly available proteomics data from this study to re-analyze the in vitro cellular consequences of SARS-CoV-2 infection by impact pathways analysis and network analysis. Notably, proteins linked to the inflammatory response, but also proteins related to chromosome segregation during mitosis, were found to be altered in response to viral infection. Upregulation of inflammatory response proteins is in line with the propagation of inflammatory reaction and lung injury that is observed in advanced stages of COVID-19 patients and which worsens with age.

Re-analysis of SARS-CoV-2-infected host cell proteomics time-course data by impact pathway analysis and network analysis: a potential link with inflammatory response

The pandemic caused by SARS-COV2 Virus/COVID-19, which was initially reported in China in December 2019, has become a major global health concern. COVID-19 can manifest with cytokine storm - an exaggerated systemic inflammatory phenomenon due to over-production of proinflammatory cytokines by immune cells that results in diffuse inflammatory lung disease and acute respiratory distress syndrome. It may be complicated by septic shock and subsequent multi-organ failure. Based on the most recently published evidence, this article will review and discuss comprehensive information on its clinical manifestations, laboratory tests, potential therapeutics, and prevention guidelines.

2019 Novel Coronavirus Pandemic: What Do We Know?

The lung is a key target of the cytokine storm that can be triggered by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), responsible for the widespread clinical syndrome known as coronavirus disease 2019 (COVID-19). Indeed, in some patients, SARS-CoV-2 promotes a dysfunctional immune response that dysregulates the cytokine secretory pattern. Hypercytokinemia underlies the hyperinflammatory state leading to injury of alveolar epithelial cells and vascular endothelial cells, as well as to lung infiltration sustained by neutrophils and macrophages. Within such a pathogenic context, interleukin-6 (IL-6) and other cytokines/chemokines play a pivotal pro-inflammatory role. Therefore, cytokines and their receptors, as well as cytokine-dependent intracellular signalling pathways can be targeted by potential therapies aimed to relieve the heavy burden of cytokine storm. In particular, the anti-IL-6-receptor monoclonal antibody tocilizumab is emerging as one of the most promising pharmacologic treatments. The reviews of this paper are available via the supplemental material section.

Lung under attack by COVID-19-induced cytokine storm: pathogenic mechanisms and therapeutic implications

The 2019 coronavirus disease (COVID-19) pandemic caused by the virus severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has created an unprecedented global crisis for the infrastructure sectors, including economic, political, healthcare, education, and research systems. Although over 90% of infected individuals are asymptomatic or manifest noncritical symptoms and will recover from the infection, those individuals presenting with critical symptoms are in urgent need of effective treatment options. Emerging data related to mechanism of severity and potential therapies for patients presenting with severe symptoms are scattered and therefore require a comprehensive analysis to focus research on developing effective therapeutics. A critical literature review suggests that the severity of SARS-CoV-2 infection is associated with dysregulation of inflammatory immune responses, which in turn inhibits the development of protective immunity to the infection. Therefore, the use of therapeutics that modulate inflammation without compromising the adaptive immune response could be the most effective therapeutic strategy.

COVID-19 as an Acute Inflammatory Disease

COVID-19 is often related to hyperinflammation that drives lung or multiorgan injury. The immunopathological mechanisms that cause excessive inflammation are under investigation and constantly updated. Here, a gene network approach was used on recently published data sets to identify possible COVID-19 inflammatory mechanisms and bioactive genes. First, network analysis of putative SARS-CoV-2 cellular receptors led to the mining of a neutrophil-response signature and relevant inflammatory genes. Second, analysis of RNA-seq data sets of lung cells infected with SARS-CoV-2 revealed that infected cells expressed neutrophil-attracting chemokines. Third, analysis of RNA-seq data sets of bronchoalveolar lavage fluid cells from COVID-19 patients identified upregulation of neutrophil genes and chemokines. Different inflammatory genes mined here, including TNFR, IL-8, CXCR1, CXCR2, ADAM10, GPR84, MME, ANPEP, and LAP3, might be druggable targets in efforts to limit SARS-CoV-2 inflammation in severe clinical cases. The possible role of neutrophils in COVID-19 inflammation needs to be studied further.

COVID-19 Hyperinflammation: What about Neutrophils?

Emerging of the COVID-19 pandemic has raised interests in the field of biology and pathogenesis of coronaviruses; including interactions between host immune reactions specific, and viral factors. Deep knowledge about the interaction between coronaviruses and the host factors could be useful to provide a better support for the disease sufferers and be advantageous for managing and treatment of the lung infection caused by the virus. At this study, we reviewed the updated information on the pathogenesis of the COVID-19 and the immune responses toward it, with a special focus on structure, genetics, and viral accessory proteins, viral replication, viral receptors, the human immune reactions, cytopathic effects, and host-related factors.

A contemporary review on pathogenesis and immunity of COVID-19 infection

Interleukin-6 (IL-6), known as an inflammatory cytokine, can be involved in many innate and adaptive immune responses. The role of IL-6 in the pathogenesis of the novel coronavirus disease 2019 (COVID-19) has recently received much more attention due to the spread of the virus and its pandemic potential. Cytokine storm is among the most critical pathological events in patients affected with coronaviruses (CoVs), i.e., severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and COVID-19, causing inflammation-induced lung injury and also occurring as a result of dysregulation of immune responses to the mentioned viruses. IL-6, along with some other inflammatory cytokines, including IL-1 beta (β), IL-8, and tumor necrosis factor-alpha (TNF-α), as well as inflammatory chemokines, can significantly contribute to, fever, lymphopenia, coagulation, lung injury, and multi-organ failure (MOF). Therefore, researchers are to explore novel approaches to treat the disease through targeting of IL-6 and its receptors based on prior experience of other disorders. In this review article, the latest findings on the role of IL-6 in the pathogenesis of COVID-19, as well as therapeutic perspectives, were summarized and discussed.

The bio-mission of interleukin-6 in the pathogenesis of COVID-19: A brief look at potential therapeutic tactics

RATIONALE: Coronavirus disease 2019 (COVID-19) is a global threat to health. Its inflammatory characteristics are incompletely understood. OBJECTIVES: To define the cytokine profile of COVID-19, and to identify evidence of immunometabolic alterations in those with severe illness. METHODS: Levels of interleukin (IL)-1ß, IL-6, IL-8, IL-10 and soluble TNF receptor 1 (sTNFR1) were assessed in plasma from healthy volunteers, hospitalized-but-stable COVID-19 patients (COVIDstable), COVID-19 patients requiring intensive care unit (ICU) admission (COVIDICU) and individuals with severe community-acquired pneumonia requiring ICU support (CAPICU). Immunometabolic markers were measured in circulating neutrophils from patients with severe COVID-19. The acute phase response of alpha-1 antitrypsin (AAT) to COVID-19 was also evaluated. MAIN RESULTS: IL-1ß, IL-6, IL-8 and sTNFR1 were all increased in patients with COVID-19. COVIDICU patients could be clearly differentiated from COVIDstable, and demonstrated higher levels of IL-1ß, IL-6 and sTNFR1 - but lower IL-10 - than CAPICU. COVID-19 neutrophils displayed altered immunometabolism, with increased cytosolic PKM2, phosphorylated PKM2, HIF-1α and lactate. The production and sialylation of AAT increased in COVID-19, but this anti-inflammatory response was overwhelmed in severe illness, with the IL-6:AAT ratio markedly higher in patients requiring ICU admission (P<0.0001). In critically unwell COVID-19 patients, increases in IL-6:AAT predicted prolonged ICU stay and mortality, while improvement in IL-6:AAT was associated with clinical resolution (P<0.0001). CONCLUSIONS: The COVID-19 cytokinemia is distinct from that of other types of pneumonia leading to organ failure and ICU need. Neutrophils undergo immunometabolic reprogramming in severe COVID-19 illness. Cytokine ratios may predict outcomes in this population. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Characterization of the Inflammatory Response to Severe COVID-19 Illness

Since the WHO declared COVID-19 a pandemic, a great effort has been made to understand this serious disease. Thousands of studies are being devoted to understanding its epidemiology, its molecular characteristics, its mechanisms, and the clinical evolution of this viral infection. However, little has been published on its pathogenesis and the host response mechanisms in the progress of the disease. Therefore, we propose a hypothesis based on strong scientific documentation, associating oxidative stress with changes found in patients with COVID-19, such as its participation in the amplification and perpetuation of the cytokine storm, coagulopathy, and cell hypoxia. Finally, we suggest a therapeutic strategy to reduce oxidative stress using antioxidants, NFkB inhibitors, Nrf2 activators, and iron complexing agents. We believe that this hypothesis can guide new studies and therapeutic strategies on this topic.

SARS-CoV-2 infection pathogenesis is related to oxidative stress as a response to aggression

SARS-CoV2 may evade innate immune response, causing uncontrolled neutrophil extracellular traps formation and multi-organ failure

Abstract Coronavirus Disease 2019 (COVID-19) was first identified in China at the end of 2019. Acute respiratory distress syndrome (ARDS) represents the most common and serious complication of COVID-19. Cytokine storms are a pathophysiological feature of COVID-19 and play an important role in distinguishing hyper-inflammatory subphenotypes of ARDS. Accordingly, in this review, we focus on hyper-inflammatory host responses in ARDS that play a critical role in the differentiated development of COVID-19. Furthermore, we discuss inflammation-related indicators that have the potential to identify hyper-inflammatory subphenotypes of COVID-19, especially for those with a high risk of ARDS. Finally, we explore the possibility of improving the quality of monitoring and treatment of COVID-19 patients and in reducing the incidence of critical illness and mortality via better distinguishing hyper- and hypo-inflammatory subphenotypes of COVID-19.

Coronavirus Disease 2019 (COVID-19): Cytokine Storms, Hyper-Inflammatory Phenotypes, and Acute Respiratory Distress Syndrome

Background Approximately 5% of patients with coronavirus disease 2019 (COVID-19) develop a life-threatening pneumonia that often occurs in the setting of increased inflammation or "cytokine storm". Anti-cytokine treatments are being evaluated but optimal patient selection remains unclear. Methods Between February 29 to April 6, 2020, 111 consecutive hospitalized patients with COVID-19 pneumonia were evaluated in a single centre retrospective study. Patients were divided in two groups: 42 severe cases (TOCI) with adverse prognostic features including raised CRP and IL-6 levels, who underwent anti-cytokine treatments, mostly tocilizumab, and 69 standard of care patients (SOC). Findings In the TOCI group, all received anti-viral therapy and 40% also received glucocorticoids. In TOCI, 62% of cases were ventilated and there were 3 deaths (17.8+/-10.6 days, mean follow up) with 7/26 cases remaining on ventilators, without improvement, and 17/26 developed bacterial superinfection. One fatality occurred in the 15 TOCI cases treated on noninvasive ventilation and 1 serious bacterial superinfection. Of the 69 cases in SOC, there was no fatalities and no bacterial complications. The TOCI group had higher baseline CRP and IL-6 elevations (p<0.0001 for both) and higher neutrophils and lower lymphocyte levels (p= 0.04 and p=0.001, respectively) with the TOCI ventilated patients having higher markers than non-ventilated TOCI patients. Interpretation Higher inflammatory markers, more superimposed infections and worse outcomes characterized ventilated TOCI cases compared to ward based TOCI therapy. Despite the confounding factors, this study suggests that therapy time in anti-cytokine randomized clinical trials will be key.

Profiling COVID-19 pneumonia progressing into the cytokine storm syndrome: results from a single Italian Centre study on tocilizumab versus standard of care.

The disease known as coronavirus disease 19 (COVID-19), potentially caused by an outbreak of the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) in Wuhan, China, has hit the world hard, and has led to an unprecedent health and economic crisis. In order to develop treatment options able to stop or ameliorate SARS-CoV-2 effects, we need to understand the biology of the virus inside cells, but this kind of studies are still scarce. A recent study investigated translatome and proteome host cell changes induced in vitro by SARS-CoV-2. In the present study, we use the publicly available proteomics data from this study to re-analyze the mechanisms altered by the virus infection by impact pathways analysis and network analysis. Proteins linked to inflammatory response, but also proteins related to chromosome segregation during mitosis, were found to be regulated. The up-regulation of the inflammatory-related proteins observed could be linked to the propagation of inflammatory reaction and lung injury that is observed in advanced stages of COVID-19 patients.

Re-analysis of SARS-CoV-2 infected host cell proteomics time-course data by impact pathway analysis and network analysis. A potential link with inflammatory response

H7N9 influenza A virus (IAV)-infected human cases are increasing and reported over 200 mortalities since its first emergence in 2013. Host inflammatory response contributes to the clearance of influenza virus; meanwhile, the induced “cytokine storm” also leads to pathological lesions. However, what inflammation-related response of the host for H7N9 influenza A virus infection to survival from injures of exuberant cytokine release is still obscure. In this research, expression pattern and histological distribution of inflammation-related genes, RIP3, NLRP3, IL-1β, TNF-α, Slit2 and Robo4 in the lung of BALB/c mice infected with two H7N9 IAV strains with only a PB2 residue 627 difference were investigated, as well as the histopathological injury of the lung. Results showed that significantly higher expression level of NLRP3, RIP3, IL-1β and TNF-α in H7N9-infected groups compared with the control would play a key role in driving lung pathological lesion. While the expression level of Slit2 and Robo4 in H7N9 rV(K627E) group had significantly increased trend than V(K627) which might be the main factor to inhibit the interstitial pneumonia and infiltration. Also, H7N9 induced the histopathological changes in the lung of infected mice, and RIP3, NLRP3, IL-1β, TNF-α, Slit2 and Robo4 showed cell-specific distribution in the lung. The results will provide basic data for further research on the mechanism of inflammatory response and understanding of the role of site 627 in PB2 in H7N9 IAVs infection. In addition, enhancing the resilience of the host vascular system to the inflammatory response by regulation of Slit2–Robo4 signaling pathway might provide a novel strategy for H7N9 IAVs infection.

Expression of inflammation-related genes in the lung of BALB/c mice response to H7N9 influenza A virus with different pathogenicity

The immune response to SARS-CoV2 is under intense investigation, but not fully understood att this moment. Severe disease is characterized by vigorous inflammatory responses in the lung, often with a sudden onset after 5-7 days of stable disease. Efforts to modulate this hyperinflammation and the associated acute respiratory distress syndrome, rely on the unraveling of the immune cell interactions and cytokines that drive such responses. Systems-level analyses are required to simultaneously capture all immune cell populations and the many protein mediators by which cells communicate. Since every patient analyzed will be captured at different stages of his or her infection, longitudinal monitoring of the immune response is critical. Here we report on a systems-level blood immunomonitoring study of 39 adult patients, hospitalized with severe COVID-19 and followed with up to 14 blood samples from acute to recovery phases of the disease. We describe an IFNg-Eosinophil axis activated prior to lung hyperinflammation and changes in cell-cell coregulation during different stages of the disease. We also map an immune trajectory during recovery that is shared among patients with severe COVID-19.

Systems-level immunomonitoring from acute to recovery phase of severe COVID-19

Abstract The novel coronavirus disease 2019 (COVID-19) has rapidly increased in pandemic scale since it first appeared in Wuhan, China, in December 2019. In these troubled days the scientific community is asking rapid replies to prevent and combat the emergency. It is generally accepted that only achieving a better understanding of the interactions between the virus and host immune response and of the pathogenesis of infection is crucial to identify valid therapeutic tools to control virus entry, replication and spread as well as to impair its lethal effects. Based on the recent research progress of SARS-CoV-2 and the results on previous coronaviruses, in this contribution we underscore some of the main unsolved problems, mostly focusing on pathogenetic aspects and host immunity to the virus. On this basis, we also touch important aspects regarding the immune response in asymptomatic subjects, the immune-evasion of SARS-CoV-2 in severe patients and differences in disease severity by age and gender.

COVID-19: unanswered questions on immune response and pathogenesis

COVID-19 is associated with 5.1% mortality. Although the virological, epidemiological, clinical, and management outcome features of COVID-19 patients have been defined rapidly, the inflammatory and immune profiles require definition as they influence pathogenesis and clinical expression of COVID-19. Here we show lymphopenia, selective loss of CD4+ T cells, CD8+ T cells and NK cells, excessive T-cell activation and high expression of T-cell inhibitory molecules are more prominent in severe cases than in those with mild disease. CD8+ T cells in patients with severe disease express high levels of cytotoxic molecules. Histochemical studies of lung tissue from one fatality show sub-anatomical distributions of SARS-CoV-2 RNA and massive infiltration of T cells and macrophages. Thus, aberrant activation and dysregulation of CD8+ T cells occur in patients with severe COVID-19 disease, an effect that might be for pathogenesis of SARS-CoV-2 infection and indicate that immune-based targets for therapeutic interventions constitute a promising treatment for severe COVID-19 patients.

Immunological and inflammatory profiles in mild and severe cases of COVID-19

Early clinical evidence suggests that severe cases of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are frequently characterized by hyperinflammation, imbalance of renin-angiotensin-aldosterone system, and a particular form of vasculopathy, thrombotic microangiopathy, and intravascular coagulopathy. In this paper, we present an immunothrombosis model of COVID-19. We discuss the underlying pathogenesis and the interaction between multiple systems, resulting in propagation of immunothrombosis, which through investigation in the coming weeks, may lead to both an improved understanding of COVID-19 pathophysiology and identification of innovative and efficient therapeutic targets to reverse the otherwise unfavorable clinical outcome of many of these patients.

Hyperinflammation and derangement of renin-angiotensin-aldosterone system in COVID-19: A novel hypothesis for clinically suspected hypercoagulopathy and microvascular immunothrombosis

Abstract Influenza virus infection is characterized by symptoms ranging from mild congestion and body aches to severe pulmonary edema and respiratory failure. While the majority of those exposed have minor symptoms and recover with little morbidity, an estimated 500,000 people succumb to IAV-related complications each year worldwide. In these severe cases, an exaggerated inflammatory response, known as “cytokine storm”, occurs which results in damage to the respiratory epithelial barrier and development of acute respiratory distress syndrome (ARDS). Data from retrospective human studies as well as experimental animal models of influenza virus infection highlight the fine line between an excessive and an inadequate immune response, where the host response must balance viral clearance with exuberant inflammation. Current pharmacological modulators of inflammation, including corticosteroids and statins, have not been successful in improving outcomes during influenza virus infection. We have reported that the amplitude of the inflammatory response is regulated by Linear Ubiquitin Assembly Complex (LUBAC) activity and that dampening of LUBAC activity is protective during severe influenza virus infection. Therapeutic modulation of LUBAC activity may be crucial to improve outcomes during severe influenza virus infection, as it functions as a molecular rheostat of the host response. Here we review the evidence for modulating inflammation to ameliorate influenza virus infection-induced lung injury, data on current anti-inflammatory strategies, and potential new avenues to target viral inflammation and improve outcomes.

Targeting the Linear Ubiquitin Assembly Complex to Modulate the Host Response and Improve Influenza A Virus Induced Lung Injury

Circulating in China and 158 other countries and areas, the ongoing COVID-19 outbreak has caused devastating mortality and posed a great threat to public health. However, efforts to identify effectively supportive therapeutic drugs and treatments has been hampered by our limited understanding of host immune response for this fatal disease. To characterize the transcriptional signatures of host inflammatory response to SARS-CoV-2 (HCoV-19) infection, we carried out transcriptome sequencing of the RNAs isolated from the bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) specimens of COVID-19 patients. Our results reveal distinct host inflammatory cytokine profiles to SARS-CoV-2 infection in patients, and highlight the association between COVID-19 pathogenesis and excessive cytokine release such as CCL2/MCP-1, CXCL10/IP-10, CCL3/MIP-1A, and CCL4/MIP1B. Furthermore, SARS-CoV-2 induced activation of apoptosis and P53 signalling pathway in lymphocytes may be the cause of patients' lymphopenia. The transcriptome dataset of COVID-19 patients would be a valuable resource for clinical guidance on anti-inflammatory medication and understanding the molecular mechansims of host response.

Transcriptomic characteristics of bronchoalveolar lavage fluid and peripheral blood mononuclear cells in COVID-19 patients

Influenza virus infection is characterized by symptoms ranging from mild congestion and body aches to severe pulmonary edema and respiratory failure. While the majority of those exposed have minor symptoms and recover with little morbidity, an estimated 500,000 people succumb to IAV-related complications each year worldwide. In these severe cases, an exaggerated inflammatory response, known as "cytokine storm", occurs which results in damage to the respiratory epithelial barrier and development of acute respiratory distress syndrome (ARDS). Data from retrospective human studies as well as experimental animal models of influenza virus infection highlight the fine line between an excessive and an inadequate immune response, where the host response must balance viral clearance with exuberant inflammation. Current pharmacological modulators of inflammation, including corticosteroids and statins, have not been successful in improving outcomes during influenza virus infection. We have reported that the amplitude of the inflammatory response is regulated by Linear Ubiquitin Assembly Complex (LUBAC) activity and that dampening of LUBAC activity is protective during severe influenza virus infection. Therapeutic modulation of LUBAC activity may be crucial to improve outcomes during severe influenza virus infection, as it functions as a molecular rheostat of the host response. Here we review the evidence for modulating inflammation to ameliorate influenza virus infection-induced lung injury, data on current anti-inflammatory strategies, and potential new avenues to target viral inflammation and improve outcomes.

BACKGROUND Severe acute respiratory coronavirus 2 (SARS-CoV-2) caused coronavirus disease 2019 (COVID-19) has become a pandemic. This study addressed the clinical and immunopathological characteristics of severe COVID-19. METHODS Sixty-nine COVID-19 patients were classified into as severe and non-severe groups to analyze their clinical and laboratory characteristics. A panel of blood cytokines was quantified over time. Biopsy specimens from two deceased cases were obtained for immunopathological, ultrastructural, and in situ hybridization examinations. RESULTS Circulating cytokines, including IL8, IL6, TNFα, IP10, MCP1, and RANTES, were significantly elevated in severe COVID-19 patients. Dynamic IL6 and IL8 were associated with disease progression. SARS-CoV-2 was demonstrated to infect type II, type I pneumocytes and endothelial cells, leading to severe lung damage through cell pyroptosis and apoptosis. In severe cases, lymphopenia, neutrophilia, depletion of CD4+ and CD8+ T lymphocytes, and massive macrophage and neutrophil infiltrates were observed in both blood and lung tissues. CONCLUSIONS A panel of circulating cytokines could be used to predict disease deterioration and inform clinical interventions. Severe pulmonary damage was predominantly attributed to both SARS-CoV-2 caused cytopathy and immunopathologic damage. Strategies that encourage pulmonary recruitment and overactivation of inflammatory cells by suppressing cytokine storm might improve the outcomes of severe COVID-19 patients.

Clinical and pathological investigation of severe COVID-19 patients.

Background The pathogenesis of COVID-19, caused by a novel strain of coronavirus (SARS-CoV-2), involves a complex host-virus interaction and is characterised by an exaggerated immune response, the specific components of which are poorly understood. Here we report the outcome of a longitudinal immune profiling study in hospitalised patients during the peak of the COVID-19 pandemic in the UK and show the relationship between immune responses and severity of the clinical presentation. Methods The Coronavirus Immune Response and Clinical Outcomes (CIRCO) study was conducted at four hospitals in Greater Manchester. Patients with SARS-CoV-2 infection, recruited as close to admission as possible, provided peripheral blood samples at enrolment and sequentially thereafter. Fresh samples were assessed for immune cells and proteins in whole blood and serum. Some samples were also stimulated for 3 hours with LPS and analysed for intracellular proteins. Results were stratified based on patient-level data including severity of symptoms and date of reported symptom onset. Findings Longitudinal analysis showed a very high neutrophil to T cell ratio and abnormal activation of monocytes in the blood, which displayed high levels of the cell cycle marker, Ki67 and low COX-2. These properties all reverted in patient with good outcome. Unexpectedly, multiple aspects of inflammation were diminished as patients progressed in severity and time, even in ITU patients not recovering. Interpretation This is the first detailed longitudinal analysis of COVID-19 patients of varying severity and outcome, revealing common features and aspects that track with severity. Patients destined for a severe outcome can be identified at admission when still displaying mild-moderate symptoms. We provide clues concerning pathogenesis that should influence clinical trials and therapeutics. Targeting pathways involved in neutrophil and monocyte release from the bone marrow should be tested in patients with COVID-19. Funding: The Kennedy Trust for Rheumatology Research, The Wellcome Trust, The Royal Society, The BBSRC, National Institute for Health Research (NIHR) Biomedical Research Centres (BRC).

Longitudinal immune profiling reveals distinct features of COVID-19 pathogenesis

Background: The recent outbreak of coronavirus disease 2019 (COVID-19) has been rapidly spreading on a global scale and poses a great threat to human health. Acute respiratory distress syndrome, characterized by a rapid onset of generalized inflammation, is the leading cause of mortality in patients with COVID-19. We thus aimed to explore the effect of risk factors on the severity of the disease, focusing on immune-inflammatory parameters, which represent the immune status of patients. Methods: A comprehensive systematic search for relevant studies published up to April 2020 was performed by using the PubMed, Web of Science, EMBASE, and China National Knowledge Internet (CNKI) databases. After extracting all available data of immune-inflammatory indicators, we statistically analyzed the risk factors of severe and non-severe COVID-19 patients with a meta-analysis. Results: A total of 4,911 patients from 29 studies were included in the final meta-analysis. The results demonstrated that severe patients tend to present with increased white blood cell (WBC) and neutrophil counts, neutrophil-lymphocyte ratio (NLR), procalcitonin (PCT), C-reaction protein (CRP), erythrocyte sedimentation rate (ESR), and Interleukin-6 (IL-6) and a decreased number of total lymphocyte and lymphocyte subtypes, such as CD4+ T lymphocyte and CD8+ T lymphocyte, compared to the non-severe patients. In addition, the WBC count>10 × 10(9)/L, lymphocyte count<1 × 10(9)/L, PCT>0.5 ng/mL, and CRP>10 mg/L were risk factors for disease progression in patients with COVID-19 (WBC count>10 × 10(9)/L: OR = 2.92, 95% CI: 1.96–4.35; lymphocyte count<1 × 10(9)/L: OR = 4.97, 95% CI: 3.53–6.99; PCT>0.5 ng/mL: OR = 6.33, 95% CI: 3.97–10.10; CRP>10 mg/L: OR = 3.51, 95% CI: 2.38–5.16). Furthermore, we found that NLR, as a novel marker of systemic inflammatory response, can also help predict clinical severity in patients with COVID-19 (OR = 2.50, 95% CI: 2.04–3.06). Conclusions: Immune-inflammatory parameters, such as WBC, lymphocyte, PCT, CRP, and NLR, could imply the progression of COVID-19. NLR has taken both the levels of neutrophil and lymphocyte into account, indicating a more complete, accurate, and reliable inspection efficiency; surveillance of NLR may help clinicians identify high-risk COVID-19 patients at an early stage.

Immune-Inflammatory Parameters in COVID-19 Cases: A Systematic Review and Meta-Analysis

Novel coronavirus disease-2019 (COVID-19) is a highly contagious respiratory-related disease induced by the newly emerged virus SARS-CoV-2. Given that inflammatory immune cells may induce severe lung injury, the involvement of immune factors in the pathogenesis of the disease cannot be overestimated. It has been demonstrated that coronaviruses (CoVs) have developed mechanisms of immune evasion, making them invisible to the immune system at an early stage of infection. The mechanism relies on inhibition of the anti-viral response of type I interferons (IFNs), which supports uncontrolled viral replication in epithelial cells. There is growing body of evidence that the fatal hyperinflammation ('cytokine storm') responsible for the severe course of COVID-19 is a consequence of massive SARS-CoV-2 replication rather than inappropriate hyperresponsiveness of the immune system. Therefore, a dampened innate anti-viral immune response seems to be the primary cause of the delayed critical cascade of uncontrolled immune events leading to fulminating systemic inflammation. The occurrence of virus transmission even in asymptomatic subjects infected with SARS-CoV-2 clearly strengthens the evidence for a key role of sufficient immune control of viral replication in a subset of cases (e.g. in children, a population with highly effective innate immune responses). Although administration of immunomodulatory therapeutics is recommended under certain conditions in the guidelines of COVID-19 management, controversies regarding treatment protocols in immunocompromised patients infected with SARS-CoV-2 still exist. Extended knowledge of clinicians on the dysregulated immune response, which is a driver of the COVID-19 outcome, may improve both therapeutic protocols and the prognosis of SARS-CoV-2 infected patients.

Dysregulation of the immune system as a driver of the critical course of the novel coronavirus disease 2019

Dysregulation of the immune system as a driver of the critical course of the novel coronavirus disease 2019.

Abstract Early clinical evidence suggests that severe cases of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are frequently characterized by hyperinflammation, imbalance of renin-angiotensin-aldosterone system, and a particular form of vasculopathy, thrombotic microangiopathy, and intravascular coagulopathy. In this paper, we present an immunothrombosis model of COVID-19. We discuss the underlying pathogenesis and the interaction between multiple systems, resulting in propagation of immunothrombosis, which through investigation in the coming weeks, may lead to both an improved understanding of COVID-19 pathophysiology and identification of innovative and efficient therapeutic targets to reverse the otherwise unfavorable clinical outcome of many of these patients.

Circulating in China and 158 other countries and areas, the ongoing COVID-19 outbreak has caused devastating mortality and posed a great threat to public health. However, efforts to identify effectively supportive therapeutic drugs and treatments has been hampered by our limited understanding of host immune response for this fatal disease. To characterize the transcriptional signatures of host inflammatory response to SARS-CoV-2 (HCoV-19) infection, we carried out transcriptome sequencing of the RNAs isolated from the bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) specimens of COVID-19 patients. Our results reveal distinct host inflammatory cytokine profiles to SARS-CoV-2 infection in patients, and highlight the association between COVID-19 pathogenesis and excessive cytokine release such as CCL2/MCP-1, CXCL10/IP-10, CCL3/MIP-1A, and CCL4/MIP1B. Furthermore, SARS-CoV-2 induced activation of apoptosis and P53 signalling pathway in lymphocytes may be the cause of patients’ lymphopenia. The transcriptome dataset of COVID-19 patients would be a valuable resource for clinical guidance on anti-inflammatory medication and understanding the molecular mechansims of host response.

OBJECTIVE: Approximately 5% of patients with coronavirus disease 2019 (COVID-19) develop a life-threatening pneumonia that often occurs in the setting of increased inflammation or "cytokine storm". Anti-cytokine treatments are being evaluated but optimal patient selection remains unclear, and the aim of our study is to address this point. METHODS: Between February 29 to April 6, 2020, 111 consecutive hospitalized patients with COVID-19 pneumonia were evaluated in a single centre retrospective study. Patients were divided in two groups: 42 severe cases (TOCI) with adverse prognostic features including raised CRP and IL-6 levels, who underwent anti-cytokine treatments, mostly tocilizumab, and 69 standard of care patients (SOC). RESULTS: In the TOCI group, all received anti-viral therapy and 40% also received glucocorticoids. In TOCI, 62% of cases were ventilated and there were three deaths (17.8 ± 10.6 days, mean follow up) with 7/26 cases remaining on ventilators, without improvement, and 17/26 developed bacterial superinfection. One fatality occurred in the 15 TOCI cases treated on noninvasive ventilation and one serious bacterial superinfection. Of the 69 cases in SOC, there was no fatalities and no bacterial complications. The TOCI group had higher baseline CRP and IL-6 elevations (p < 0.0001 for both) and higher neutrophils and lower lymphocyte levels (p = 0.04 and p = 0.001, respectively) with the TOCI ventilated patients having higher markers than non-ventilated TOCI patients. CONCLUSION: Higher inflammatory markers, more infections and worse outcomes characterized ventilated TOCI cases compared to ward based TOCI. Despite the confounding factors, this suggests that therapy time in anti-cytokine randomized trials will be key.

Profiling COVID-19 pneumonia progressing into the cytokine storm syndrome: Results from a single Italian Centre study on tocilizumab versus standard of care

Background Infection with SARS-CoV-2 manifests itself as a mild respiratory tract infection in the majority of individuals, which progresses to a severe pneumonia and acute respiratory distress syndrome (ARDS) in 10-15% of patients. Inflammation plays a crucial role in the pathogenesis of ARDS, with immune dysregulation in severe COVID-19 leading to a hyperinflammatory response. A comprehensive understanding of the inflammatory process in COVID-19 is lacking. Methods In this prospective, multicenter observational study, patients with PCR-proven or clinically presumed COVID-19 admitted to the intensive care unit (ICU) or clinical wards were included. Demographic and clinical data were obtained and plasma was serially collected. Concentrations of IL-6, TNF-, complement components C3a, C3c and the terminal complement complex (TCC) were determined in plasma by ELISA. Additionally, 269 circulating biomarkers were assessed using targeted proteomics. Results were compared between ICU and non ICU patients. Findings A total of 119 (38 ICU and 91 non ICU) patients were included. IL-6 plasma concentrations were elevated in COVID-19 (ICU vs. non ICU, median 174.5 pg/ml [IQR 94.5-376.3 vs. 40.0 pg/ml [16.5-81.0]), whereas TNF- concentrations were relatively low and not different between ICU and non ICU patients (median 24.0 pg/ml [IQR 16.5-33.5] and 21.5 pg/ml [IQR 16.0-33.5], respectively). C3a and terminal complement complex (TCC) concentrations were significantly higher in ICU vs. non ICU patients (median 556.0 ng/ml [IQR 333.3-712.5]) vs. 266.5 ng/ml [IQR 191.5-384.0 for C3a and 4506 mAU/ml [IQR 3661-6595 vs. 3582 mAU/ml [IQR 2947-4300] for TCC) on the first day of blood sampling. Targeted proteomics demonstrated that IL-6 (logFC 2.2), several chemokines and hepatocyte growth factor (logFC 1.4) were significantly upregulated in ICU vs. non ICU patients. In contrast, stem cell factor was significantly downregulated (logFC -1.3) in ICU vs. non ICU patients, as were DPP4 (logFC -0.4) and protein C inhibitor (log FC -1.0), the latter two factors also being involved in the regulation of the kinin-kallikrein pathway. Unsupervised clustering pointed towards a homogeneous pathogenetic mechanism in the majority of patients infected with SARS-CoV-2, with patient clustering mainly based on disease severity. Interpretation We identified important pathways involved in dysregulation of inflammation in patients with severe COVID-19, including the IL-6, complement system and kinin-kallikrein pathways. Our findings may aid the development of new approaches to host-directed therapy.

A systems approach to inflammation identifies therapeutic targets in SARS-CoV-2 infection

OBJECTIVE: Approximately 5% of patients with coronavirus disease 2019 (COVID-19) develop a life-threatening pneumonia that often occurs in the setting of increased inflammation or “cytokine storm”. Anti-cytokine treatments are being evaluated but optimal patient selection remains unclear, and the aim of our study is to address this point. METHODS: Between February 29 to April 6, 2020, 111 consecutive hospitalized patients with COVID-19 pneumonia were evaluated in a single centre retrospective study. Patients were divided in two groups: 42 severe cases (TOCI) with adverse prognostic features including raised CRP and IL-6 levels, who underwent anti-cytokine treatments, mostly tocilizumab, and 69 standard of care patients (SOC). RESULTS: In the TOCI group, all received anti-viral therapy and 40% also received glucocorticoids. In TOCI, 62% of cases were ventilated and there were 3 deaths (17.8 ± 10.6 days, mean follow up) with 7/26 cases remaining on ventilators, without improvement, and 17/26 developed bacterial superinfection. One fatality occurred in the 15 TOCI cases treated on noninvasive ventilation and 1 serious bacterial superinfection. Of the 69 cases in SOC, there was no fatalities and no bacterial complications. The TOCI group had higher baseline CRP and IL-6 elevations (p < 0.0001 for both) and higher neutrophils and lower lymphocyte levels (p = 0.04 and p = 0.001, respectively) with the TOCI ventilated patients having higher markers than non-ventilated TOCI patients. CONCLUSION: Higher inflammatory markers, more infections and worse outcomes characterized ventilated TOCI cases compared to ward based TOCI. Despite the confounding factors, this suggests that therapy time in anti-cytokine randomized trials will be key.

Profiling COVID-19 pneumonia progressing into the cytokine storm syndrome: results from a single Italian Centre study on tocilizumab versus standard of care

The current pandemic of COVID-19 has caused severe morbidity and mortality across the globe. People with a smoking history have severe disease outcomes by COVID-19 infection. Epidemiological studies show that old age and pre-existing disease conditions (hypertension and diabetes) result in severe disease outcome and mortality amongst COVID-19 patients. Evidences suggest that the S1 domain of the SARS-CoV-2 (causative agent of COVID-19) membrane spike has a high affinity towards the angiotensin-converting enzyme 2 (ACE2) receptor found on the host’s lung epithelium. Likewise, TMPRSS2 protease has been shown to be crucial for viral activation thus facilitating the viral engulfment. The viral entry has been shown to cause ‘cytokine storm’ involving excessive production of pro-inflammatory cytokines/chemokines including IL-6, TNF-α, IFN-γ, IL-2, IL-7, IP-10, MCP-3 or GM-CSF, which is augmented by smoking. Future research could target these inflammatory-immunological responses to develop effective therapy for COVID-19. This mini-review provides a consolidated account on the role of inflammation and immune responses, proteases, and epithelial permeability by smoking and vaping during SARS-CoV2 infection with future directions of research, and provides a list of the potential targets for therapies particularly controlling cytokine storms in the lung.

SARS-CoV-2 COVID-19 susceptibility and lung inflammatory storm by smoking and vaping

The pandemic caused by SARS-COV2 Virus/COVID-19, which was initially reported in China in December 2019, has become a major global health concern COVID-19 can manifest with cytokine storm - an exaggerated systemic inflammatory phenomenon due to over-production of proinflammatory cytokines by immune cells that results in diffuse inflammatory lung disease and acute respiratory distress syndrome It may be complicated by septic shock and subsequent multi-organ failure Based on the most recently published evidence, this article will review and discuss comprehensive information on its clinical manifestations, laboratory tests, potential therapeutics, and prevention guidelines

2019 Novel Coronavirus Pandemic: What Do We Know?

BACKGROUND: The rapid outbreak of coronavirus disease 2019 (COVID-19) has turned into a public health emergency of international concern. Epidemiological research has shown that sex is associated with the severity of COVID-19, but the underlying mechanism of sex predisposition remains poorly understood. We aim to study the gendered differences in inflammation reaction, and the association with severity and mortality of COVID-19. METHODS: In this retrospective study, we enrolled 548 COVID-19 inpatients from Tongji Hospital from 26 January to 5 February 2020, and followed up to 3 March 2020. Epidemiological, demographic and clinical features, and inflammatory indexes were collected and compared between males and females. The Cox proportional hazard regression model was applied to identify the gendered effect on mortality of COVID-19 after adjusting for age, comorbidity, and smoking history. The multiple linear regression method was used to explore the influence of sex on inflammation reaction. RESULTS: Males had higher mortality than females did (22.2% vs 10.4%), with an hazard ratio of 1.923 (95% confidence interval, 1.181-3.130); elder age and comorbidity were significantly associated with decease of COVID-19 patients. Excess inflammation reaction was related to severity of COVID-19. Male patients had greater inflammation reaction, with higher levels of interleukin 10, tumor necrosis factor-α, lactose dehydrogenase, ferritin, and hyper-sensitive C-reactive protein, but a lower lymphocyte count than females adjusted by age and comorbidity. CONCLUSIONS: Sex, age, and comorbidity are critical risk factors for mortality of COVID-19. Excess innate immunity and proinflammation activity, and deficiency in adaptive immunity response promote males, especially elder males, to develop a cytokine storm, causing potential acute respiratory distressed syndrome, multiple organ failure and decease.

Gendered effects on inflammation reaction and outcome of COVID-19 patients in Wuhan

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a member of the genus Betacoronavirus within the family Coronaviridae. It is an enveloped single-stranded positive-sense RNA virus. Since December of 2019, a global expansion of the infection has occurred with widespread dissemination of coronavirus disease 2019 (COVID-19). COVID-19 often manifests as only mild cold-like symptomatology, but severe disease with complications occurs in 15% of cases. Respiratory failure occurs in severe disease that can be accompanied by a systemic inflammatory reaction characterized by inflammatory cytokine release. In severe cases, fatality is caused by the rapid development of severe lung injury characteristic of acute respiratory distress syndrome (ARDS). Although ARDS is a complication of SARS-CoV-2 infection, it is not viral replication or infection that causes tissue injury; rather, it is the result of dysregulated hyperinflammation in response to viral infection. This pathology is characterized by intense, rapid stimulation of the innate immune response that triggers activation of the Nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome pathway and release of its products including the proinflammatory cytokines IL-6 and IL-1β. Here we review the literature that describes the pathogenesis of severe COVID-19 and NLRP3 activation and describe an important role in targeting this pathway for the treatment of severe COVID-19.

Targeting the NLRP3 Inflammasome in Severe COVID-19

The pandemic caused by the novel coronavirus SARS-CoV-2 has placed an unprecedented burden on healthcare systems around the world. In patients who experience severe disease, acute respiratory distress is often accompanied by a pathological immune reaction, sometimes referred to as 'cytokine storm'. One hallmark feature of the profound inflammatory state seen in patients with COVID-19 who succumb to pneumonia and hypoxia is marked elevation of serum cytokines, especially interferon gamma, tumor necrosis factor alpha, interleukin 17 (IL-17), interleukin 8 (IL-8) and interleukin 6 (IL-6). Initial experience from the outbreaks in Italy, China and the USA has anecdotally demonstrated improved outcomes for critically ill patients with COVID-19 with the administration of cytokine-modulatory therapies, especially anti-IL-6 agents. Although ongoing trials are investigating anti-IL-6 therapies, access to these therapies is a concern, especially as the numbers of cases worldwide continue to climb. An immunology-informed approach may help identify alternative agents to modulate the pathological inflammation seen in patients with COVID-19. Drawing on extensive experience administering these and other immune-modulating therapies, the Society for Immunotherapy of Cancer offers this perspective on potential alternatives to anti-IL-6 that may also warrant consideration for management of the systemic inflammatory response and pulmonary compromise that can be seen in patients with severe COVID-19.

The Society for Immunotherapy of Cancer perspective on regulation of interleukin-6 signaling in COVID-19-related systemic inflammatory response

BACKGROUND: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory coronavirus 2 (SARS-CoV-2), has become a pandemic. This study addresses the clinical and immunopathological characteristics of severe COVID-19. METHODS: Sixty-nine patients with COVID-19 were classified into severe and nonsevere groups to analyze their clinical and laboratory characteristics. A panel of blood cytokines was quantified over time. Biopsy specimens from 2 deceased cases were obtained for immunopathological, ultrastructural, and in situ hybridization examinations. RESULTS: Circulating cytokines, including IL-8, IL-6, TNF-α, IP10, MCP1, and RANTES, were significantly elevated in patients with severe COVID-19. Dynamic IL-6 and IL-8 were associated with disease progression. SARS-CoV-2 was demonstrated to infect type II and type I pneumocytes and endothelial cells, leading to severe lung damage through cell pyroptosis and apoptosis. In severe cases, lymphopenia, neutrophilia, depletion of CD4+ and CD8+ T lymphocytes, and massive macrophage and neutrophil infiltrates were observed in both blood and lung tissues. CONCLUSIONS: A panel of circulating cytokines could be used to predict disease deterioration and inform clinical interventions. Severe pulmonary damage was predominantly attributed to both cytopathy caused by SARS-CoV-2 and immunopathologic damage. Strategies that prohibit pulmonary recruitment and overactivation of inflammatory cells by suppressing cytokine storm might improve the outcomes of patients with severe COVID-19.

Clinical and pathological investigation of patients with severe COVID-19

The novel coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is sorely testing health care systems and economies around the world and is rightly considered as the major health emergency in a century. Despite the course of the disease appearing to be mild in many cases, a significant proportion of symptomatic patients develop pneumonia requiring hospitalisation or progress to manifest respiratory complications leading to intensive care treatment. Potential interventions for SARS-CoV2-associated pneumonia are being tested, some of which holding promise, but as of today none of these has yet demonstrated outstanding efficacy in treating COVID-19. In this article, we discuss fresh perspectives and insights into the potential role of immune dysregulation in COVID-19 as well as similarities with systemic inflammatory response in sepsis and the rationale for exploring novel treatment options affecting host immune response.

The unleashing of the immune system in COVID-19 and sepsis: the calm before the storm?

The seventh human coronavirus SARS-CoV2 belongs to the cluster of extremely pathogenic coronaviruses like SARS-CoV and MERS-CoV, which are established to cause lower respiratory tract infection. The viral infection can be fatal as the disease advances to pneumonia followed by acute respiratory distress syndrome (ARDS). Increasingly higher cytokine concentration on account of over-stimulated immune response against the virus, or the ‘cytokine storm’, is the reason behind the manifestation of lethal clinical symptoms. In this article, we discuss the immune pathogenesis of cytokine storm and its relation with SARS-CoV2/COVID-19 risk factors. People with underlying risk factors are more susceptible to fatal complications of COVID-19 infection leading to poor clinical outcome. The increased pro-inflammatory immune status in patients with risk factors (diabetes, hypertension, cardiovascular disease, COPD) exacerbates the Cytokine-storm of COVID-19 to a Cytokine Super Cyclone. We also overviewed antiviral immune response provided by BCG vaccine involving the IL-1β, IL-6 and TNF-α secretion via ‘trained monocytes’, which confers early protection against SARS-CoV2.

Cytokine Storm in COVID-19 patients transforms to a Cytokine Super Cyclone in patients with risk factors

COVID-19 as an Acute Inflammatory Disease.

The pandemic caused by the novel coronavirus SARS-CoV-2 has placed an unprecedented burden on healthcare systems around the world. In patients who experience severe disease, acute respiratory distress is often accompanied by a pathological immune reaction, sometimes referred to as ‘cytokine storm’. One hallmark feature of the profound inflammatory state seen in patients with COVID-19 who succumb to pneumonia and hypoxia is marked elevation of serum cytokines, especially interferon gamma, tumor necrosis factor alpha, interleukin 17 (IL-17), interleukin 8 (IL-8) and interleukin 6 (IL-6). Initial experience from the outbreaks in Italy, China and the USA has anecdotally demonstrated improved outcomes for critically ill patients with COVID-19 with the administration of cytokine-modulatory therapies, especially anti-IL-6 agents. Although ongoing trials are investigating anti-IL-6 therapies, access to these therapies is a concern, especially as the numbers of cases worldwide continue to climb. An immunology-informed approach may help identify alternative agents to modulate the pathological inflammation seen in patients with COVID-19. Drawing on extensive experience administering these and other immune-modulating therapies, the Society for Immunotherapy of Cancer offers this perspective on potential alternatives to anti-IL-6 that may also warrant consideration for management of the systemic inflammatory response and pulmonary compromise that can be seen in patients with severe COVID-19.

Viral sepsis is rare, and its real incidence is not known. SARS-CoV-2 infection causes the release of a significant amount of pro-inflammatory cytokines that aggravates interstitial pneumonia and evolves in viral sepsis with prominent hypercoagulability. We believe it is useful and advisable to establish early immunomodulator therapy and the prophylaxis anticoagulant therapy should be rethought.

Thromboinflammatory response in SARS-CoV-2 sepsis.

INTRODUCTION: There have been recent mounting concerns regarding multiple reports stating a significantly elevated relative-risk of COVID-19 mortality amongst the Black and Minority Ethnic (BAME) population. An urgent national enquiry investigating the possible reasons for this phenomenon has been issued in the UK. Inflammation is at the forefront of COVID-19 research as disease severity appears to correlate with pro-inflammatory cytokine dysregulation. This narrative review aims to shed light on the novel, pathophysiological role of inflammation in contributing towards the increased COVID-19 mortality risk amongst the BAME population. METHODS: Searches in PubMed, Medline, Scopus, medRxiv and Google Scholar were performed to identify articles published in English from inception to 18th June 2020. These databases were searched using keywords including: 'COVID-19' or 'Black and Minority Ethnic' or 'Inflammation'. A narrative review was synthesized using these included articles. RESULTS: We suggest a novel pathophysiological mechanism by which acute inflammation from COVID-19 may augment existing chronic inflammation, in order to potentiate a 'cytokine storm' and thus the more severe disease phenotype observed in the BAME population. Obesity, insulin resistance, cardiovascular disease, psychological stress, chronic infections and genetic predispositions are all relevant factors which may be contributing to elevated chronic systemic inflammation amongst the BAME population. CONCLUSION: Overall, this review provides early insights and directions for ongoing research regarding the pathophysiological mechanisms that may explain the severe COVID-19 disease phenotype observed amongst the BAME population. We suggest 'personalization' of chronic disease management, which can be used with other interventions, in order to tackle this.

COVID-19 and ethnicity: A novel pathophysiological role for inflammation

INTRODUCTION: The cytokine release syndrome (CRS) of COVID-19 is associated with the development of critical illness requiring multi-organ support. Further research is required to halt progression of multi-organ injury induced by hyper-inflammation. AREAS COVERED: PubMed/MEDLINETM databases were accessed between May 9th-June 9th, 2020, to review the latest perspectives on the treatment and pathogenesis of CRS. EXPERT OPINION: Over-activity of chemotaxis triggers a macrophage activation syndrome (MAS) resulting in the release of pro-inflammatory cytokines. IL-6 and TNF- α are at the forefront of hyper-inflammation. The inflammatory cascade induces endothelial activation and capillary leak, leading to circulatory collapse and shock. As endothelial dysfunction persists, there is activation of the clotting cascade and microvascular obstruction. Continued endothelial activation results in multi-organ failure, regardless of pulmonary tissue damage. We propose that targeting the endothelium may interrupt this cycle. Immuno-modulating therapies have been suggested, however, further data is necessary to confirm that they do not jeopardize adaptive immunity. Inhibition of IL-6 and the Janus Kinase, signal transducer and activator of transcription proteins pathway (JAK/STAT), are favorable targets. Remote ischemic conditioning (RIC) reduces the inflammation of sepsis in animal models and should be considered as a low risk intervention, in combination with cardiovascular protection.

The cytokine storm of COVID-19: a spotlight on prevention and protection

AIM: Coronavirus disease 2019 (COVID-19) is a novel highly contagious infection caused by SARS-CoV-2, which has been became a global public health challenge. The pathogenesis of this virus is not yet clearly understood, but there is evidence of a hyper-inflammatory immune response in critically ill patients, which leads to acute respiratory distress syndrome (ARDS) and multi-organ failure. MATERIAL AND METHODS: A literature review was performed to identify relevant articles on COVID-19 published up to April 30, 2020. The search resulted in 361 total articles. After reviewing the titles and abstracts for inclusion, some irrelevant papers were excluded. Additional relevant articles were identified from a review of citations referenced. KEY FINDINGS: SARS-CoV-2, directly and indirectly, affects the immune system and avoids being eliminated in early stages. On the other hand, the secretion of inflammatory cytokines creates critical conditions that lead to multi-organ failure. SIGNIFICANCE: The immune system which is affected by the virus tries to respond via a cytokine storm and hyperinflammation, which itself leads to further multi-organ damage and even death.

The immune system and COVID-19: Friend or foe?

Cytokine storm is an excessive immune response to external stimuli. The pathogenesis of the cytokine storm is complex. The disease progresses rapidly, and the mortality is high. Certain evidence shows that, during the coronavirus disease 2019 (COVID-19) epidemic, the severe deterioration of some patients has been closely related to the cytokine storm in their bodies. This article reviews the occurrence mechanism and treatment strategies of the COVID-19 virus-induced inflammatory storm in attempt to provide valuable medication guidance for clinical treatment.

The pathogenesis and treatment of the `Cytokine Storm' in COVID-19

Severe acute respiratory syndrome (SARS) caused by a novel human coronavirus (CoV), designated SARS-CoV, is a highly contagious respiratory disease with the lungs as a major target. Although the exact mechanism of SARS-CoV pathogenesis remains unknown, an intense, ill-regulated local inflammatory response has been suggested as partially responsible for the devastating lung pathology. We investigated the interaction of SARS-CoV with human macrophages (Mphi) and dendritic cells (DC), two key innate immune cells of the host immune system, by focusing on their susceptibility to viral infection and subsequent responses (e.g., phenotypic maturation, T cell-priming activity, phagocytosis, and cytokine production). We found neither cell to be permissive for SARS-CoV replication. However, incubation of Mphi and DC with live, but not gamma irradiation-inactivated, viruses appeared to better sustain their viability. Also, exposure to infectious SARS-CoV led to the phenotypic and functional maturation of DC, with regard to MHC class II and costimulatory molecule expression, T cell-stimulatory capacity, and cytokine production, respectively. Cytokine production was also observed for Mphi, which were refractory to cell surface phenotypic changes. Strikingly, live SARS-CoV could further prime cell types to respond to a suboptimal dose of bacterial LPS (100 ng/ml), resulting in massive release of IL-6 and IL-12. However, the endocytic capacity (e.g., Ag capture) of Mphi was significantly compromised upon exposure to infectious SARS-CoV. This study is the first demonstration that although SARS-CoV does not productively infect human Mphi or DC, it appears to exert differential effects on Mphi and DC maturation and functions, which might contribute to SARS pathogenesis.

Severe acute respiratory syndrome and the innate immune responses: modulation of effector cell function without productive infection.

COVID-19 caused by a novel agent SARS-CoV-2 progressed to a pandemic condition and resulted in a major public health concern worldwide, leading to social and economic issues at the same time. The pathogenesis of COVID-19 starts with the bonding of the virus to ACE-2 receptors expressed in many tissues, and the triggered excessive immune response plays a critical role in the course of the disease. The cytokine storm that occurs upon excessive production of pro-inflammatory cytokines is considered responsible for the severe progression of the disease and the organ damage. However, the accurate pathophysiological mechanism of the disease, which progresses with various clinical presentations, is still substantially unknown. While various studies have been conducted on the effect of genetic polymorphism on the course and severity of the disease, the presence of a significant effect has not been proven yet. The clinical course of the disease is variable, with clinical representation ranging from 81% mild course to 14% severe course along with 5% critical course in patients. Asymptomatic course is considered to be higher than expected, although its frequency is not known exactly. Older adults and those with comorbidities are exposed to a more severe disease course. The disease progress with various symptoms, such as fever, cough, dyspnea, malaise, myalgia, taste and smell dysfunctions, diarrhea, and headache. A range of complications (Acute Respiratory Distress Syndrome, thromboembolic conditions, arrhythmia and cardiac events, secondary infections) could be seen during the course of the disease. Varied laboratory tests are vital to determine the severity and prognosis of the disease, along with the condition and exposure of the affected systems during the course of COVID-19.

COVID-19: Pathogenesis, Genetic Polymorphism, Clinical Features and Laboratory Findings.

Patients with COVID-19 who require ICU admission might have the cytokine storm. It is a state of out-of-control release of a variety of inflammatory cytokines. The molecular mechanism of the cytokine storm has not been explored extensively yet. The attachment of SARS-CoV-2 spike glycoprotein with angiotensin-converting enzyme 2 (ACE2), as its cellular receptor, triggers complex molecular events that leads to hyperinflammation. Four molecular axes that may be involved in SARS-CoV-2 driven inflammatory cytokine overproduction are addressed in this work. The virus-mediated down-regulation of ACE2 causes a burst of inflammatory cytokine release through dysregulation of the renin-angiotensin-aldosterone system (ACE/angiotensin II/AT1R axis), attenuation of Mas receptor (ACE2/MasR axis), increased activation of [des-Arg9]-bradykinin (ACE2/bradykinin B1R/DABK axis), and activation of the complement system including C5a and C5b-9 components. The molecular clarification of these axes will elucidate an array of therapeutic strategies to confront the cytokine storm in order to prevent and treat COVID-19 associated acute respiratory distress syndrome.

COVID-19 cytokine storm: The anger of inflammation

The severe acute respiratory syndrome coronavirus 2 (SARS-COv-2) is the etiologic agent of the 2019 coronavirus disease (COVID19). The majority of infected people presents flu like symptoms and among them 15-20% develops a severe interstitial pneumonitis (IP) that may eventually evolve in acute respiratory distress syndrome (ARDS). IP is caused by the viral glycoprotein spike (S) binding to the angiotensin converting enzyme 2 (ACE2) expressed on the surface of alveolar pneumocytes. The virus is recognized by the "pattern recognition receptors" (PRR) of the immune cells that release cytokines activating more immune cells that produce a large number of pro-inflammatory cytokines, tissue factors and vasoactive peptides. Affected patients might develop the "cytokine storm syndrome," a fulminant and fatal hypercytokinaemia with multiorgan failure. In patients infected by SARS-COv-2 increase in T-helper 2 (TH2) cytokines (IL-4 and IL10) are reported in addition to the T-helper 1 (TH1) cytokines (IL1B, IFNÎ³, IP10, and MCP1) previously detected in other coronavirus infections. Cytokines and other molecules involved in immune response and inflammation are conceivable therapeutic targets for IP and ARDS, improving symptoms and decreasing intensive care unit admissions. To this aim off label drugs may be used taking into consideration the window timing for immunosuppressive drugs in virus infected patients. Some off label therapeutic options and preclinical evidence drugs are herein considered.

Fighting the Host Reaction to SARS-COv-2 in Critically Ill Patients: The Possible Contribution of Off-Label Drugs

RATIONALE Coronavirus disease 2019 (COVID-19) is a global threat to health. Its inflammatory characteristics are incompletely understood. OBJECTIVES To define the cytokine profile of COVID-19, and to identify evidence of immunometabolic alterations in those with severe illness. METHODS Levels of interleukin (IL)-1β, IL-6, IL-8, IL-10 and soluble TNF receptor 1 (sTNFR1) were assessed in plasma from healthy volunteers, hospitalized-but-stable COVID-19 patients (COVIDstable), COVID-19 patients requiring intensive care unit (ICU) admission (COVIDICU) and individuals with severe community-acquired pneumonia requiring ICU support (CAPICU). Immunometabolic markers were measured in circulating neutrophils from patients with severe COVID-19. The acute phase response of alpha-1 antitrypsin (AAT) to COVID-19 was also evaluated. MAIN RESULTS IL-1β, IL-6, IL-8 and sTNFR1 were all increased in patients with COVID-19. COVIDICU patients could be clearly differentiated from COVIDstable, and demonstrated higher levels of IL-1β, IL-6 and sTNFR1 - but lower IL-10 - than CAPICU. COVID-19 neutrophils displayed altered immunometabolism, with increased cytosolic PKM2, phosphorylated PKM2, HIF-1α and lactate. The production and sialylation of AAT increased in COVID-19, but this anti-inflammatory response was overwhelmed in severe illness, with the IL-6:AAT ratio markedly higher in patients requiring ICU admission (P<0.0001). In critically unwell COVID-19 patients, increases in IL-6:AAT predicted prolonged ICU stay and mortality, while improvement in IL-6:AAT was associated with clinical resolution (P<0.0001). CONCLUSIONS The COVID-19 cytokinemia is distinct from that of other types of pneumonia leading to organ failure and ICU need. Neutrophils undergo immunometabolic reprogramming in severe COVID-19 illness. Cytokine ratios may predict outcomes in this population. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Characterization of the Inflammatory Response to Severe COVID-19 Illness.

SARS-CoV-2 infection, named COVID-19, can lead to a dysregulated immune response and abnormal coagulation responsible for a viral sepsis. In this review, we specify physiopathological mechanisms of each phase of COVID-19 - viral, immune and pro-thrombotic - notably because they involve different treatment. Finally, we specify the physiopathological mechanisms of organ injury.

COVID-19 : physiopathologie d'une maladie à plusieurs visages./ [COVID-19: Pathogenesis of a multi-faceted disease]

Coronavirus disease-2019 (COVID-19) is caused by the newly emerged virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was recently declared as a pandemic by the World Health Organization. In its severe form, the disease is characterized by acute respiratory distress syndrome, and there are no targeted intervention strategies to treat or prevent it. The immune response is thought to both contribute to the pathogenesis of disease and provide protection during its resolution. Thus, understanding the immune response to SARS-CoV-2 is of the utmost importance for developing and testing vaccines and therapeutics. In this review, we discuss the earliest knowledge and hypotheses of the mechanisms of immune pathology in the lung during acute infection as well at the later stages of disease resolution, recovery, and immune memory formation.

Early Insights into Immune Responses during COVID-19.

This paper presents an evidence-based strategy for improving clinical outcomes in COVID-19. Recommendations are based on the phases of the disease, because optimal interventions for one phase may not be appropriate for a different phase. The four phases addressed are: Prevention, Infection, Inflammation and Recovery. Underlying this phased approach is recognition of emerging evidence for two different components of pathophysiology, early infection and late stage severe complications. These two aspects of the disease suggest two different patterns of clinical emphasis that seem on the surface to be not entirely concordant. We describe the application of therapeutic strategies and appropriate tactics that address four main stages of disease progression for COVID-19. Emerging evidence in COVID-19 suggests that the SARS-CoV-2 virus may both evade the innate immune response and kill macrophages. Delayed innate immune response and a depleted population of macrophages can theoretically result in a blunted antigen presentation, delaying and diminishing activation of the adaptive immune response. Thus, one clinical strategy involves supporting patient innate and adaptive immune responses early in the time course of illness, with the goal of improving the timeliness, readiness, and robustness of both the innate and adaptive immune responses. At the other end of the disease pathology spectrum, risk of fatality in COVID-19 is driven by excessive and persistent upregulation of inflammatory mechanisms associated with cytokine storm. Thus, the second clinical strategy is to prevent or mitigate excessive inflammatory response to prevent the cytokine storm associated with high mortality risk. Clinical support for immune system pathogen clearance mechanisms involves obligate activation of immune response components that are inherently inflammatory. This puts the goals of the first clinical strategy (immune activation) potentially at odds with the goals of the second strategy(mitigation of proinflammatory effects). This creates a need for discernment about the time course of the illness and with that, understanding of which components of an overall strategy to apply at each phase of the time course of the illness. We review evidence from early observational studies and the existing literature on both outcomes and mechanisms of disease, to inform a phased approach to support the patient at risk for infection, with infection, with escalating inflammation during infection, and at risk of negative sequelae as they move into recovery.

Evidence Supporting a Phased Immuno-physiological Approach to COVID-19 From Prevention Through Recovery.

As of April 20, 2020, over time, the COVID-19 pandemic has resulted in 157 970 deaths out of 2 319 066 confirmed cases, at a Case Fatality Rate of ~6.8%. With the pandemic rapidly spreading, and health delivery systems being overwhelmed, it is imperative that safe and effective pharmacotherapeutic strategies are rapidly explored to improve survival. In this paper, we use established and emerging evidence to propose a testable hypothesis that, a vicious positive feedback loop of des-Arg(9)-bradykinin- and bradykinin-mediated inflammation â injury â inflammation, likely precipitates life threatening respiratory complications in COVID-19. Through our hypothesis, we make the prediction that the FDA-approved molecule, icatibant, might be able to interrupt this feedback loop and, thereby, improve the clinical outcomes. This hypothesis could lead to basic, translational, and clinical studies aimed at reducing COVID-19 morbidity and mortality.

A hypothesized role for dysregulated bradykinin signaling in COVID-19 respiratory complications

The inflammatory response to severe acute respiratory syndrome-related coronavirus 2 infection has a direct impact on the clinical outcomes of coronavirus disease 2019 patients. Of the many innate immune pathways that are engaged by severe acute respiratory syndrome-related coronavirus 2, we highlight the importance of the inflammasome pathway. We discuss available pharmaceutical agents that target a critical component of inflammasome activation, signaling leading to cellular pyroptosis, and the downstream cytokines as a promising target for the treatment of severe coronavirus disease 2019-associated diseases.

Inflammasomes and Pyroptosis as Therapeutic Targets for COVID-19.

The severe acute respiratory syndrome coronavirus 2 (SARS-COv-2) is the etiologic agent of the 2019 coronavirus disease (COVID19). The majority of infected people presents flu like symptoms and among them 15–20% develops a severe interstitial pneumonitis (IP) that may eventually evolve in acute respiratory distress syndrome (ARDS). IP is caused by the viral glycoprotein spike (S) binding to the angiotensin converting enzyme 2 (ACE2) expressed on the surface of alveolar pneumocytes. The virus is recognized by the “pattern recognition receptors” (PRR) of the immune cells that release cytokines activating more immune cells that produce a large number of pro-inflammatory cytokines, tissue factors and vasoactive peptides. Affected patients might develop the “cytokine storm syndrome,” a fulminant and fatal hypercytokinaemia with multiorgan failure. In patients infected by SARS-COv-2 increase in T-helper 2 (TH2) cytokines (IL-4 and IL10) are reported in addition to the T-helper 1 (TH1) cytokines (IL1B, IFNγ, IP10, and MCP1) previously detected in other coronavirus infections. Cytokines and other molecules involved in immune response and inflammation are conceivable therapeutic targets for IP and ARDS, improving symptoms and decreasing intensive care unit admissions. To this aim off label drugs may be used taking into consideration the window timing for immunosuppressive drugs in virus infected patients. Some off label therapeutic options and preclinical evidence drugs are herein considered.

Influenza A virus (IAV) infects the respiratory tract in humans and causes significant morbidity and mortality worldwide each year. Aggressive inflammation, known as a cytokine storm, is thought to cause most of the damage in the lungs during IAV infection. Dysfunctional coagulation is a common complication in pathogenic influenza, manifested by lung endothelial activation, vascular leak, disseminated intravascular coagulation and pulmonary microembolism. Importantly, emerging evidence shows that an uncontrolled coagulation system, including both the cellular (endothelial cells and platelets) and protein (coagulation factors, anticoagulants and fibrinolysis proteases) components, contributes to the pathogenesis of influenza by augmenting viral replication and immune pathogenesis. In this review, we focus on the underlying mechanisms of the dysfunctional coagulatory response in the pathogenesis of IAV.

Aberrant coagulation causes a hyper-inflammatory response in severe influenza pneumonia

Summary Cytokine storm is an excessive immune response to external stimuli. The pathogenesis of the cytokine storm is complex. The disease progresses rapidly, and the mortality is high. Certain evidence shows that, during the coronavirus disease 2019 (COVID-19) epidemic, the severe deterioration of some patients has been closely related to the cytokine storm in their bodies. This article reviews the occurrence mechanism and treatment strategies of the COVID-19 virus-induced inflammatory storm in attempt to provide valuable medication guidance for clinical treatment.

The recent COVID-19 pandemic has had a significant impact on our lives and has rapidly expanded to reach more than 4 million cases worldwide by May 2020. These cases are characterized by extreme variability, from a mild or asymptomatic form lasting for a few days up to severe forms of interstitial pneumonia that may require ventilatory therapy and can lead to patient death.Several hypotheses have been drawn up to understand the role of the interaction between the infectious agent and the immune system in the development of the disease and the most severe forms; the role of the cytokine storm seems important.Innate immunity, as one of the first elements of guest interaction with different infectious agents, could play an important role in the development of the cytokine storm and be responsible for boosting more severe forms. Therefore, it seems important to study also this important arm of the immune system to adequately understand the pathogenesis of the disease. Research on this topic is also needed to develop therapeutic strategies for treatment of this disease.

COVID 19: a clue from innate immunity

The recent COVID-19 pandemic has had a significant impact on our lives and has rapidly expanded to reach more than 4 million cases worldwide by May 2020. These cases are characterized by extreme variability, from a mild or asymptomatic form lasting for a few days up to severe forms of interstitial pneumonia that may require ventilatory therapy and can lead to patient death. Several hypotheses have been drawn up to understand the role of the interaction between the infectious agent and the immune system in the development of the disease and the most severe forms; the role of the cytokine storm seems important. Innate immunity, as one of the first elements of guest interaction with different infectious agents, could play an important role in the development of the cytokine storm and be responsible for boosting more severe forms. Therefore, it seems important to study also this important arm of the immune system to adequately understand the pathogenesis of the disease. Research on this topic is also needed to develop therapeutic strategies for treatment of this disease.

COVID 19: a clue from innate immunity

INTRODUCTION The cytokine release syndrome (CRS) of COVID-19 is associated with the development of critical illness requiring multi-organ support. Further research is required to halt progression of multi-organ injury induced by hyper-inflammation. AREAS COVERED PubMed/MEDLINETM databases were accessed between May 9th-June 9th, 2020, to review the latest perspectives on the treatment and pathogenesis of CRS. EXPERT OPINION Over-activity of chemotaxis triggers a macrophage activation syndrome (MAS) resulting in the release of pro-inflammatory cytokines. IL-6 and TNF- α are at the forefront of hyper-inflammation. The inflammatory cascade induces endothelial activation and capillary leak, leading to circulatory collapse and shock. As endothelial dysfunction persists, there is activation of the clotting cascade and microvascular obstruction. Continued endothelial activation results in multi-organ failure, regardless of pulmonary tissue damage. We propose that targeting the endothelium may interrupt this cycle. Immuno-modulating therapies have been suggested, however, further data is necessary to confirm that they do not jeopardize adaptive immunity. Inhibition of IL-6 and the Janus Kinase, signal transducer and activator of transcription proteins pathway (JAK/STAT), are favorable targets. Remote ischemic conditioning (RIC) reduces the inflammation of sepsis in animal models and should be considered as a low risk intervention, in combination with cardiovascular protection.

The cytokine storm of COVID-19: a spotlight on prevention and protection.

COVID-19 is an infectious disease characterized by several important systemic problems such as severe pneumonia. One of mechanisms responsible of these systemic problems is the release of pro-inflammatory cytokines, such as interleukin (IL)-1beta and IL-6(Conti et al., 2020). The binding of virus to TRL (Toll Like Receptor) can determine the release of pro-IL-1beta with successive activation and production of active mature IL-1beta, responsible of lung inflammation, fever and fibrosis(Conti et al., 2020). The interstitial pneumonia is linked to an over-production of IL-6. Based on this principle, several researchers started the use of an anti-arthritis drug, tocilizumab, for its anti-IL-6 action.

New intriguing possibility for prevention of coronavirus pneumonitis: Natural purified polyphenols

COVID-19 is an infectious disease caused by 2019-nCoV and characterizes as an atypical pneumonia. Since 2019-nCoV is a newly emerging virus, the pathogenesis of COVID-19 is not well known. Most patients had a self-limited course, and some became severe even death. In this review, the authors compared two coronavirus outbreaks during the past two decades: the SARS-CoV and 2019-nCoV. Among the biological nature of the pathogens, viral receptor distribution on the human cells, and the pathological findings in the targeted organs and clinical features of the patients with the diseases, found similarities and differences between the two diseases. Due to the shared receptor ACE2 and the pathological similarities of the SARS-CoV and 2019-nCoV diseases. They proposed a pathogenesis model for COVID-19. Like the SARS-CoV disease, COVID-19 is a systematic disease and targets the lungs, vasculatures, and the immune system. The basic pathogenesis involves two interlinked processes: a severe lung inflammation and immune deficiency, both of which are related to an inappropriate immune response and over-production of cytokines. Thus, treatment approaches should include antiviral and anti-proinflammatory cytokines, anti-infectious and life support therapies, especially in patients with severe diseases.

[From SARS to COVID-19: pathogens, receptor, pathogenesis and principles of the treatment].

Clinical manifestations of COVID-19 vary from asymptomatic virus shedding, non-specific pharyngitis, to pneumonia with silent hypoxia and respiratory failure. Dendritic cells and macrophages are sentinel cells for innate and adaptive immunity that affect the pathogenesis of SARS and MERS. However, the interplay between SARS-CoV-2 and these cell types remains unknown. Herein, we investigated the infection and host response of monocyte-derived dendritic cells (moDCs) and macrophages (MDMs) infected by SARS-CoV-2. We demonstrated that moDCs and MDMs were permissive to SARS-CoV-2 infection and protein expression but did not support productive virus replication. Importantly, SARS-CoV-2 launched an attenuated interferon response in both cell types. Additionally, SARS-CoV-2 triggered significant pro-inflammatory cytokine/chemokine expression in MDMs but not in moDCs. Further investigations suggested that this attenuated immune response to SARS-CoV-2 in moDCs was associated with viral antagonism of STAT1 phosphorylation. These findings on pathogenesis may explain the mild and insidious course of COVID-19 till late deterioration.

Attenuated interferon and pro-inflammatory response in SARS-CoV-2-infected human dendritic cells is associated with viral antagonism of STAT1 phosphorylation

As the outbreak of the new coronavirus (SARS-CoV-2) infection is spreading globally, great effort is being made to understand the disease pathogenesis and host factors that predispose to disease progression in an attempt to find a window of opportunity for intervention. In addition to the direct cytopathic effect of the virus, the host hyper-inflammatory response has emerged as a key factor in determining disease severity and mortality. Accumulating clinical observations raised hypotheses to explain why some patients develop more severe disease while others only manifest mild or no symptoms. So far, Covid-19 management remains mainly supportive. However, many researches are underway to clarify the role of antiviral and immunomodulating drugs in changing morbidity and mortality in patients who become severely ill. This review summarizes the current state of knowledge on the interaction between SARS-CoV-2 and the host immune system and discusses recent findings on proposed pharmacologic treatments.

Recent Insight into SARS-CoV2 Immunopathology and Rationale for Potential Treatment and Preventive Strategies in COVID-19

Coronaviruses including severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2, also known as 2019-nCoV especially in China) replicate and divide in host cell. During this they are partly hidden from the innate immune responses although inflammatory consequences of viral replication still occur. We propose that anti-inflammatory antiviral prostaglandins may not only restrict viral replication but can also prevent inflammatory responses in the lungs and other vital organs that are known to be part of the immuno-pathogenesis of coronavirus disease-19 (COVID-19). The combination of anti-inflammatory antiviral prostaglandins with interferons may lead to the clearance of viruses inside the growth-restricted infected cells. However, further experimental studies and clinical trials should be conducted to evaluate the safety and efficacy of these possible therapies.

Immuno-pathogenesis of nCOVID-19 and a possible host-directed therapy including anti-inflammatory and anti-viral prostaglandin (PG J(2)) for effective treatment and reduce the death toll

The beginning of 2020 has seen the emergence of COVID-19, an outbreak caused by a novel coronavirus, SARS-CoV-2, an important pathogen for humans. There is an urgent need to better understand this new virus and to develop ways to control its spread. In Iran, the first case of the COVID-19 was reported after spread from China and other countries. Fever, cough, and fatigue were the most common symptoms of this virus. In worldwide, the incubation period of COVID-19 was 3 to 7 days and approximately 80% of infections are mild or asymptomatic, 15% are severe, requiring oxygen, and 5% are critical infections, requiring ventilation. To mount an antiviral response, the innate immune system recognizes molecular structures that are produced by the invasion of the virus. COVID-19 infection induces IgG antibodies against N protein that can be detected by serum as early as day 4 after the onset of disease and with most patients seroconverting by day 14. Laboratory evidence of clinical patients showed that a specific T-cell response against SARS-CoV-2 is important for the recognition and killing of infected cells, particularly in the lungs of infected individuals. At present, there is no specific antiviral therapy for COVID-19 and the main treatments are supportive. In this review, we investigated the innate and acquired immune responses in patients who recovered from COVID-19, which could inform the design of prophylactic vaccines and immunotherapy for the future.

Immune responses and pathogenesis of SARS-CoV-2 during an outbreak in Iran: Comparison with SARS and MERS

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently emerged in Wuhan, Hubei-China, as responsible for the coronavirus disease 2019 (COVID-19) and then spread rapidly worldwide. While most individuals remain asymptomatic or develop only mild symptoms, approximately 5% develop severe forms of COVID-19 characterized by acute respiratory distress syndrome (ARDS) and multiple-organ failure (MOF) that usually require intensive-care support and often yield a poor prognosis. SUMMARY: The pathophysiology of COVID-19 is far from being completely understood, and the lack of effective treatments leads to a sense of urgency to develop new therapeutic strategies based on pathophysiological assumptions. The exaggerated cytokine release in response to viral infection, a condition known as cytokine release syndrome (CRS) or cytokine storm, is emerging as the mechanism leading to ARDS and MOF in COVID-19, thus endorsing the hypothesis that properly timed anti-inflammatory therapeutic strategies could improve patients' clinical outcomes and prognosis. KEY MESSAGES: The objective of this article is to explore and comment on the potential role of the promising immunomodulatory therapies using pharmacological and nonpharmacological approaches to overcome the dysregulated proinflammatory response in COVID-19.

Weathering the Cytokine Storm in COVID-19: Therapeutic Implications

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently emerged in Wuhan, Hubei-China, as responsible for the coronavirus disease 2019 (COVID-19) and then spread rapidly worldwide. While most individuals remain asymptomatic or develop only mild symptoms, approximately 5% develop severe forms of COVID-19 characterized by acute respiratory distress syndrome (ARDS) and multiple-organ failure (MOF) that usually require intensive-care support and often yield a poor prognosis. SUMMARY: The pathophysiology of COVID-19 is far from being completely understood, and the lack of effective treatments leads to a sense of urgency to develop new therapeutic strategies based on pathophysiological assumptions. The exaggerated cytokine release in response to viral infection, a condition known as cytokine release syndrome (CRS) or cytokine storm, is emerging as the mechanism leading to ARDS and MOF in COVID-19, thus endorsing the hypothesis that properly timed anti-inflammatory therapeutic strategies could improve patients' clinical outcomes and prognosis. Key Messages: The objective of this article is to explore and comment on the potential role of the promising immunomodulatory therapies using pharmacological and nonpharmacological approaches to overcome the dysregulated proinflammatory response in COVID-19.

COVID-19 is an infectious disease caused by 2019-nCoV and characterizes as an atypical pneumonia. Since 2019-nCoV is a newly emerging virus, the pathogenesis of COVID-19 is not well known. Most patients had a self-limited course, and some became severe even death. In this review, the authors compared two coronavirus outbreaks during the past two decades: the SARS-CoV and 2019-nCoV. Among the biological nature of the pathogens, viral receptor distribution on the human cells, and the pathological findings in the targeted organs and clinical features of the patients with the diseases, found similarities and differences between the two diseases had been found. Due to the shared receptor ACE2 and the pathological similarities of the SARS-CoV and 2019-nCoV diseases,authors proposed a pathogenesis model for COVID-19. Like the SARS-CoV disease, COVID-19 is a systematic disease and targets the lungs, vasculatures, and the immune system. The basic pathogenesis involves two interlinked processes: a severe lung inflammation and immune deficiency, both of which were related to an inappropriate immune response and over-production of cytokines. Thus, treatment approaches should include antiviral and anti-proinflammatory cytokines, anti-infectious and life support therapies, especially in patients with severe diseases.

[From SARS to COVID-19: pathogens, receptor, pathogenesis and principles of the treatment]

The first case of human transmission of SARS-CoV-2 was reported in China in December 2019. A few months later, this viral infection had spread worldwide and became a pandemic. The disease caused by SARS-CoV-2, termed COVID-19, is multifactorial and associated with both specific antiviral as well as inflammatory responses, the extent of which may determine why some individuals are asymptomatic while others develop serious complications. Here we review possible life-threating immune events that can occur during disease progression to uncover key factors behind COVID-19 severity and provide suggestions for interventions with repurposed drugs in well-controlled and randomized clinical trials. These drugs include therapeutics with potential to inhibit SARS-CoV-2 entry into host cells such as serine protease inhibitors of the cellular protease TMPS2 and drugs targeting the renin-angiotensin system; antivirals with potential to block SARS-CoV-2 replication or factors that could boost the antiviral response; monoclonal antibodies targeting pro-inflammatory cytokines that drive the hyperinflammatory response during COVID-19 progression toward the severe stage and therapeutics that could ameliorate the function of the lungs. Furthermore, in order to help make more informed decisions on the timing of the intervention with the drugs listed in this review, we have grouped these therapeutics according to the stage of COVID-19 progression that we considered most appropriate for their mechanism of action.

Lessons Learned to Date on COVID-19 Hyperinflammatory Syndrome: Considerations for Interventions to Mitigate SARS-CoV-2 Viral Infection and Detrimental Hyperinflammation

COVID-19 caused by a novel agent SARS-CoV-2 progressed to a pandemic condition and resulted in a major public health concern worldwide, leading to social and economic issues at the same time. The pathogenesis of COVID-19 starts with the bonding of the virus to ACE2 receptors expressed in many tissues, and the triggered excessive immune response plays a critical role in the course of the disease. The cytokine storm that occurs upon excessive production of pro-inflammatory cytokines is considered responsible for the severe progression of the disease and the organ damage. However, the accurate pathophysiological mechanism of the disease, which progresses with various clinical presentations, is still substantially unknown. While various studies have been conducted on the effect of genetic polymorphism on the course and severity of the disease, the presence of a significant effect has not been proven yet. The clinical course of the disease is variable, with clinical representation ranging from 81% mild course to 14% severe course along with 5% critical course in patients. Asymptomatic course is considered to be higher than expected, although its frequency is not known exactly. Older adults and those with comorbidities are exposed to a more severe disease course. The disease progress with various symptoms, such as fever, cough, dyspnea, malaise, myalgia, taste and smell dysfunctions, diarrhea, and headache. A range of complications (acute respiratory distress syndrome, thromboembolic conditions, arrhythmia and cardiac events, secondary infections) could be seen during the course of the disease. Varied laboratory tests are vital to determine these verity and prognosis of the disease, along with the condition and exposure of the affected systems during thecourse of COVID-19.

COVID-19: pathogenesis, genetic polymorphism, clinical features and laboratory findings

Avian influenza A (H5N1) and severe acute respiratory syndrome (SARS) coronavirus are infections that cause a severe viral pneumonia leading to acute respiratory dysfunction syndrome and carry a high case-fatality rate. We have investigated innate immune responses to both viruses using primary human macrophages and respiratory epithelial cells as in vitro models. In contrast to human influenza A H1NI viruses, the H5N1 viruses hyper-induce cytokines (tumour necrosis factor [TNF]alpha, interferon beta) and chemokines (IP10, MIP1alpha, MCP) in in vitro cultures of primary human macrophages. A similar differential effect is observed in primary human bronchial epithelial cells and in type 2 pneumocytes although TNFalpha is not induced in respiratory epithelial cells. The cell signalling pathways responsible for this differential effect remain to be explored. Preliminary data suggest that such differential signalling involves p38 MAP kinase rather than NF-kappaB. SARS coronavirus infection of primary human macrophages is associated with a strong induction of chemokines without an associated type 1 interferon response. These observations may be relevant in disease pathogenesis.

Pathogenesis of avian flu H5N1 and SARS.

The novel coronavirus disease (COVID-19) pandemic is placing significant strains on health systems, scientific communities, essential public services, and economies all over the world. In this context, the world´s scientific biomedical establishment is unleashing an unprecedented response to the COVID-19 pandemic. This is a battle against time, considering the thousands of human lives are lost every day. In this commentary, based on a very recent research report, we intend to highlight how a new mechanism describing the RAGE transactivation produced by Ang II-mediated ATR1 activation can run continuously and thus, reinforcing a sustained inflammation in lungs, due to the SARS-Cov-2-mediated imbalance of the ACE/And II/ATR1 pathway.

SARS-CoV-2-mediated inflammatory response in lungs: should we look at RAGE?

The pandemia of coronavirus disease 2019 (COVID-19) has caused more than 355,000 confirmed deaths worldwide. However, publications on postmortem findings are scarce. We present the pulmonary findings in four cases of fatal COVID-19 with a spectrum of lung pathology reflecting disease course and duration, invasive therapies, and laboratory features. Early disease is characterized by neutrophilic, exudative capillaritis with microthrombosis and high levels of IL-1beta and IL-6. Later stages are associated with diffuse alveolar damage and ongoing intravascular thrombosis in small to medium-sized pulmonary vessels, occasionally with areas of infarction equivalents, accompanied by laboratory features of disseminated intravascular coagulation. In late stages, organizing pneumonia with extensive intra-alveolar proliferation of fibroblasts and marked metaplasia of alveolar epithelium can be observed. Viral RNA is encountered in the lung, with virus particles in endothelial cells and pneumocytes. In many patients, multi-organ failure with severe liver damage sets in finally, possibly as consequence of an early-onset pro-inflammatory cytokine storm and/or thrombotic microangiopathy.

The evolution of pulmonary pathology in fatal COVID-19 disease: an autopsy study with clinical correlation

Abstract Severe COVID-19 associated pneumonia patients may exhibit features of systemic hyper-inflammation designated under the umbrella term of macrophage activation syndrome (MAS) or cytokine storm, also known as secondary haemophagocytic lymphohistocytosis (sHLH). This is distinct from HLH associated with immunodeficiency states termed primary HLH -with radically different therapy strategies in both situations. COVID-19 infection with MAS typically occurs in subjects with adult respiratory distress syndrome (ARDS) and historically, non-survival in ARDS was linked to sustained IL-6 and IL-1 elevation. We provide a model for the classification of MAS to stratify the MAS-like presentation in COVID-19 pneumonia and explore the complexities of discerning ARDS from MAS. We discuss the potential impact of timing of anti-cytokine therapy on viral clearance and the impact of such therapy on intra-pulmonary macrophage activation and emergent pulmonary vascular disease.

The Role of Cytokines including Interleukin-6 in COVID-19 induced Pneumonia and Macrophage Activation Syndrome-Like Disease