bluuebunny/crossref_metadata_2025_split huggingface dataset:
A systems biology approach unravels the host response to West Nile virus infection in human dendritic cells
Authors: Bowen James R , Suthar Mehul S 
Published: January 2023

Abstract
West Nile virus (WNV) is a neurotropic Flavivirus and the leading cause of mosquito-borne encephalitis in the United States. Previous studies in mice have found that dendritic cells (DCs) are pivotal for viral control and programming of antiviral immunity in a RIG-I like receptor (RLR) and type I interferon (IFN) dependent manner. To gain a better understanding of human WNV infection, we evaluated infection of human monocyte DCs (moDCs). We found that moDCs support productive WNV infection and that stimulation of RLR and type I IFN signaling potently restricts viral replication. Most intriguingly, we observed significant variability in viral infection of moDCs generated from different donors, ranging from 6–56% of cells infected by 48 hours post infection. To define the antiviral landscape during WNV infection, we performed mRNA sequencing and found that, in contrast to RLR and type I IFN signaling, WNV infection partially triggers expression of antiviral defense response related genes. Despite strong induction of IFNβ during WNV infection, we observed minimal expression of cytokines that promote antiviral T cell immunity (IL-4, IL-12, IL-7, IL-15) and costimulatory molecules (CD80, CD86, CD40) at the transcriptional and protein level. Using weighted gene co-expression network analysis combined with cis-regulatory sequence analysis, we identified STAT5 as an important regulatory node downstream of RLR signaling. Most intriguingly, we found that STAT5 was not induced during WNV infection, suggesting that WNV dampens DC activation by preventing STAT5 activation. Further studies are underway to better understand how RLR signaling promotes STAT5 activation and to define the viral factors that regulate STAT5 activation.
Ly6Chi monocytes control acute Ross River virus infection through an IRF7-dependent mechanism that can be counteracted by determinants in nsP1
Authors: Haist Kelsey Cornell , Burrack Kristina S , Diamond Michael S , Suthar Mehul S , Morrison Thomas E 
Published: January 2023

Abstract
Chikungunya virus (CHIKV) and Ross River virus (RRV) are mosquito-transmitted alphaviruses that cause large epidemics of debilitating musculoskeletal disease. Monocytes have been implicated in the pathogenesis of these infections; however, their specific roles are not clearly defined. To investigate the role of inflammatory Ly6Chi CCR2+ monocytes in alphavirus pathogenesis, we used CCR2-DTR transgenic mice, enabling depletion of these cells by administering diphtheria toxin (DT). Compared to DT-treated WT mice, DT-treated CCR2-DTR+ mice exhibited reduced weight gain and more severe disease signs following RRV infection. DT-treated CCR2-DTR+ mice had reduced numbers of monocytes in circulation and musculoskeletal tissues compared to control mice. Further supporting a role for inflammatory monocytes in control of acute alphavirus infection, depletion of CCR2+ cells restored virulence and increased viral loads in musculoskeletal tissue of mice infected with RRV encoding attenuating mutations in nsP1 to levels in monocyte-depleted mice infected with fully virulent RRV. A similar increase in viral loads was observed in tissues of DT-treated CCR2-DTR+;Rag1−/− mice infected with the nsP1 mutant virus. Furthermore, adoptive transfer of WT, but not Irf7−/−, Ly6Chi monocytes into DT-treated CCR2-DTR+ mice reversed the increased viral loads of the nsP1 mutant virus. In vitro, co-culture of Ly6Chi monocytes with RRV-infected cells resulted in induction of type I IFN gene expression in monocytes that was MAVS- and IRF3/IRF7-dependent. Collectively, these data suggest that IRF7-dependent functions of monocytes are critical for control of acute alphavirus infection, and that determinants in nsP1 may counteract these responses.
The emerging role of apoptosis-associated speck-like protein containing a CARD (ASC) in dendritic cell metabolism and function.
Authors: McKeithen Danielle N , Omosun Yusuf , Ryans Khamia , Simoneaux Tankya , Ananaba Godwin , Eko Francis , Black Carolyn , Igietseme Joseph , Blas-Machado Uriel , He Qing 
Published: January 2023

Abstract
Chlamydia trachomatis (C. trachomatis) is a major infectious bacterial agent that causes sexually transmitted infections (STIs) worldwide. The regulatory functions of dendritic cells (DCs) play a major role in protective immunity against Chlamydia infections. The mechanism(s) underlying this immunomodulation are not fully understood. The inflammasome adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC) regulates the direction of immunity against such bacterial infections. In this study, we assessed the effect of ASC on the metabolism and function of Chlamydia infected DCs. Our results revealed that mitochondria of infected ASC−/− DCs had a gradual disruption of the cristae compared to the normal narrow pleomorphic cristae of uninfected wild type (WT) DCs and ASC−/− and infected WT DCs. In addition to the damaged mitochondria, we observed ASC−/− DCs had significantly reduced pyruvate production; the output of the metabolism of glucose known as glycolysis, following Chlamydia infection. Finally, the DCs from Chlamydia infected ASC−/− mice also displayed defective activation and antigen presentation. Our results suggest that ASC may play a role in cellular respiration of Chlamydia infected DCs, starting from glycolysis to the electron transport chain (ETC) which occurs within the mitochondria, thereby effecting the actions and functions of these DCs.
Transgelin-2 mimics bacterial SipA and promotes membrane ruffling and phagocytosis in lipopolysaccharide-activated macrophages
Authors: Jun Chang-Duk , Kim Hye-Ran 
Published: January 2023

Abstract
Some bacteria utilize their secreted proteins to induce massive actin polymerization at the site of invasion in host cells. Salmonella protein SipA polymerizes host actin under low ionic conditions, where it is usually completely suppressed, and induces membrane ruffling as an infection mechanism. However, no protein that possesses SipA function has been identified in eukaryotic cells. We show here that transgelin-2 – which reveals a similar function to SipA in vitro – is dramatically induced in macrophages in response to lipopolysaccharide via partially the NF-κB pathways. Transgelin-2 intensively localizes at the actin-rich membrane ruffles during fMLP stimulation. Interestingly, macrophages with trangelin-2 deficiency (TAGLN2−/−) reveal a dramatic reduction of membrane ruffles with attenuated membrane dynamics, resulting in retarded phagocytic functions. Collectively, these results suggest that host macrophages have evolved to utilize the same mechanism of bacterial infection to engulf invaded bacteria.
Resident memory CD8+ T cells in the liver require presentation by non-parenchymal cells to differentiate
Authors: Bertolino Patrick J , Wong Yik Chun , Sierro Frederic , Lu Bo , Tay Szun Szun , Wood Nicole A. W. , McGuffog Claire , Alexander Ian E. , McCaughan Geoffrey W. , Bowen David G. 
Published: January 2023

Abstract
Tissue-resident memory T cells (TRM) have been identified in different organs including skin and lung. Whether TRM can differentiate in the liver is unknown. To induce intrahepatic CD8+ T cell responses, recipient mice were transferred with anti-OVA transgenic T cells and treated with recombinant adeno-associated viral vectors (rAAV) that target mouse hepatocytes to induce de novo OVA expression in the liver. We have recently shown that a low rAAV dose induced a low antigen load and allowed the development of intrahepatic effector T cells. We investigated here whether these cells differentiated into TRM.
When 1–5% of hepatocytes expressed OVA, functional memory OVA-specific CD8+ T cells expressing CD69, a common TRM marker, were established in the liver. Intra-vital multi-photon microscopy experiments revealed that these memory cells moved slowly and against the blood flow, suggesting that they were patrolling the hepatic sinusoids. To test the ability of these cells to recirculate, livers containing memory T cells were transplanted into naive recipients. Most donor memory CD8+ T cells were detected within the transplanted livers and very few recirculated into lymphoid tissues, suggesting that they were liver resident. Importantly, when OVA presentation was restricted to hepatocytes, naïve CD8+ T cells became effectors but failed to develop into TRM.
In summary, low numbers of antigen-expressing hepatocytes promote the differentiation of liver CD8+ TRM. Although hepatocytes are critical in providing antigen, the differentiation of intrahepatic CD8+ TRM requires non-hepatocyte antigen-presenting cells. Our results have important implications for vaccine development and for the treatment of hepatotropic infections.
The generation of CD8+CD103+ tissue resident memory cells is decreased in the brain of B7-H1 knockouts after virus infection
Authors: Pavelko Kevin D , Dong Haidong 
Published: January 2023

Abstract
The generation of CD8+ tissue resident memory T-cells (TRM) ensures rapid recognition of viruses after secondary infection and is important for long term defense against tumor formation. We find that intracranial infection with Theiler’s murine encephalomyelitis virus (TMEV) generates a robust CD8+ effector response after acute infection. This response resolves with virus clearance and only CD8+CD103+ brain TRM remain. Much is known about the development of acute T-cell responses to TMEV, however less is known about how TRM are generated and maintained within the brain. Previously, we found that B7-H1 prevents the entry of effector CD8+ T-cells into the memory pool. In the current studies we explore the role of B7-H1 in the development and maintenance of brain TRM. We find that B7-H1 expression within the host tissues is important for maintaining TRM in the brain after TMEV infection. By studying acute and long-term post-infected B7-H1 knockout and wild-type mice we find that B7-H1 contributes to the formation and maintenance of TRM. The expression of B7-H1 is required within the host tissues to promote this memory population as the absence of B7-H1 on T-cells did not alter TRM formation. In addition, we find an increase in CD103 negative antigen non-specific CD8+ PD1+ T-cells in B7-H1 knockout hosts, a population previously identified as CD8+ regulatory T cells. This suggests that B7-H1 may also control this population of tissue resident CD8+ regulatory T cells (TRR). These findings will be important for further understanding the PD1/B7-H1 axis and its role in TRM and TRR development and for understanding how therapies that target these molecules can be optimized to promote T-cell memory formation and maintenance when used as therapy.
Age-associated oxidation of innate immune proteins in the lung mucosa alters the host response to Mycobacterium tuberculosis
Authors: Moliva Juan I. , Sasindran Smitha J. , Rajaram Murugesan V.S. , Schlesinger Larry S. , Turner Joanne , Torrelles Jordi B. 
Published: January 2023

Abstract
Age-associated immune changes are a risk factor for the development of tuberculosis (TB); however the phenomenon of inflammaging, a state of heightened systemic inflammation observed in the elderly, particularly within the lung mucosa has not been addressed. Mycobacterium tuberculosis (M.tb) infection results in bacterial deposition in the lung alveoli where they are bathed in alveolar lining fluid (ALF). ALF contains soluble innate factors that mediate the M.tb-host cell encounter and subsequent immune response. Recent studies indicate that local inflammation and oxidation occur within the ALF. We hypothesize that ALF components lose their function as we age, and this deficiency favors the establishment of M.tb infection. Previously, we reported increased oxidation of proteins within ALF from human adult (ages 25–44) and elderly (ages &gt;65) populations, in addition to elevated basal levels of inflammatory cytokines and complement components. Here, we extended our findings to explore the impact of adult or elderly ALF during M.tb infection. Although the levels of SP-A and C3 were elevated in elderly ALF, their binding to M.tb was reduced, suggesting a defect in innate immune function with age. To evaluate the impact of ALF age-associated changes in vivo, mice were infected with M.tb pre-exposed to adult or elderly ALF. Mice infected with elderly ALF-M.tb had significantly increased bacterial growth within the lung and spleen compared to adult ALF-M.tb infected mice, suggesting that loss of innate immune function within ALF could have long term consequences in controlling M.tb infection. We conclude that M.tb may benefit from the declining host defense function of the lung mucosa in the elderly, driving host susceptibility to TB.
Bone loss in HLA-DRβ1-bearing humanized mice following oral challenge with Porphyromonas gingivalis
Authors: Brand David D , Sandal Indra , Luo Jiwen , Prislovsky Amanda , Whittington Karen , Dong Chen , Rosloniec Edward , Karydis Anastasios 
Published: January 2023

Abstract
Periodontal disease (PD) is a chronic pro-inflammatory response to oral pathogens such as Porphyromonas gingivalis which culminates in alveolar bone loss and loss of dental structure and function. Like rheumatoid arthritis (RA), periodontal disease is influenced strongly by lifestyle factors such as tobacco use, but also greatly influenced by genetic components, such as the “shared epitope,” which refers to a conserved linear sequence of amino acids in the DRβ1 chain of the HLA-DRα/β heterodimer between amino acids 67 and 74. Aggressive PD (the most destructive form of PD) is also now thought to be associated with specific HLA haplotypes including DRβ1. Using IL-17Frfp and Foxp3gfpreporters engineered into I-A° C57BL/6 mice expressing chimeric mouse/human HLA-DRβ1 (B6.DR1 mice), we find that gingival brushing with P gingivalis results in a rapid Th17 response in the peripheral blood and cervical lymph nodes, which decreases shortly after brushing. Evidence of a chronic infection can be detected in these nodes three months after oral inoculation. In addition to Th17 responses, we also find a concomitant increase in Th17-related cytokine production that parallels the Th17 activity. Furthermore, we measured a brisk production of antibodies directed against P. gingivalis and also against cyclic citrullinated peptides (these ACPAs are widely used as the principle early diagnostic for RA) as well as a loss in trabecular bone that can be detected in peri-articular bone structures, e.g. distal to the alveolar bone structures normally measured in PD models. Our findings suggest that periodontal disease can have far-reaching effects in bone morphology which may be driven by Th17/cytokine/ACPA activity even in the absence of other pathologies.
Determining transcriptional networks regulating the response of alveolar macrophages to Mycobacterium tuberculosis
Authors: Rothchild Alissa , Amon Lynn , Mai Dat , Aderem Alan 
Published: January 2023

Abstract
Mycobacterium tuberculosis (Mtb) continues to be a major global health problem, infecting nearly one-third of the world’s population and leading to around 1.5 million deaths each year. Current drug regimens last 6–9 months and there is still no effective vaccine for adults. It is still not fully understood how innate immune cells first respond to Mtb within the lung.
Alveolar macrophages (AMs) are the first cells in the lung to become infected with Mtb after aerosol exposure. Therefore, these macrophages play a crucial role in establishing the initial inflammatory response to Mtb and the priming environment of the adaptive response. Previously, technical limitations in cell isolation and RNA sequencing restricted gene expression studies of Mtb-infected macrophages to in vitro culture systems. These studies may have missed crucial signaling pathways unique to the immunoregulatory lung environment surrounding AMs.
To investigate the in situ response of AMs to Mtb, we developed a high-dose aerosol murine infection model with fluorescent-tagged bacteria to isolate Mtb-infected AMs at early time points after infection by fluorescence-activated cell sorting. We have now measured the global gene expression profiles of both naïve and Mtb-infected AMs by RNA-seq. Preliminary data has revealed numerous regulatory and immune pathways that are altered in response to Mtb infection. Pathway enrichment analysis identified the oxidative stress response as one of the most altered pathways and promoter scanning has identified Nrf2, a master transcription factor of the oxidative stress response, as a predicted regulator. Further network analysis of these pathways and their effects on subsequent disease outcome is currently being undertaken.
Interferon-gamma and Effector Cell Activation are Required for Antibody-Mediated Immunity against Genital Chlamydia Infection
Authors: Naglak Elizabeth Kathryn , Morrison Sandra G. , Morrison Richard P. 
Published: January 2023

Abstract
Defining the mechanisms of immunity conferred by the combination of antibody and CD4+ T cells is fundamental to designing an efficacious chlamydial vaccine. Using the Chlamydia muridarum genital infection model of mice, which replicates many features of human C. trachomatis infection and avoids the characteristic low virulence of C. trachomatis in the mouse, we previously demonstrated a central role for antibody in immunity to chlamydial infection. We found that antibody alone was not protective. Instead, protection appeared to be conferred through an undefined antibody-cellular interaction. Using gene knockout mice and in vivo cellular depletion methods, antibody-mediated protection was shown to be solely dependent on the activation of an effector cell population in genital tract tissues by CD4+ T cells. Furthermore, the CD4+ T cell-secreted cytokine interferon-gamma (IFNγ) was found to be a key component of the protective antibody response. The function of IFNγ was not related to the immunoglobulin class or magnitude of the Chlamydia-specific antibody response or to recruitment of an effector cell population to genital tract tissue. Rather, IFNγ appears to be necessary for activation of the effector cell population that functions in antibody-mediated chlamydial immunity. Ongoing studies aim to identify the effector cell population(s) involved in the antibody-mediated protective response. Our results confirm the central role of antibody and CD4+ T cells in immunity to chlamydia reinfection, and demonstrate a key function for IFNγ in antibody-mediated protection.
Expression of human hTLR4/MD2 in vivo in mice alters infection with C. burnetii
Authors: Robison Amanda , Hedges Jodi F , Kimmel Emily , Hajjar Adeline M. , Jutila Mark A. 
Published: January 2023

Abstract
Human and mouse TLR4/MD2 molecules respond differently to specific types of LPS. Their response to normally acylated LPS is similar, but they respond differently to hypoacylated LPS found on specific gram-negative bacteria. The LPS of Coxiella burnetii is hypoacylated, heavily glycosylated and is known to cause a minimal response by human cells. We hypothesized that mice expressing human TLR4/MD2 (hTLR4/MD2) molecules would respond differently to C. burnetii infection compared to wild type mice. Mice expressing hTLR4/MD2 molecules had enhanced weight loss, and more bacteria in tissues than did wild-type mice. Bone marrow chimera experiments indicated that mice expressing hTLR4/MD2 on stromal/epithelia cells had more severe disease and enhanced bacterial replication compared to when mouse TLR4 was expressed on these cells. Surprisingly, hTLR4 expression on hematopoietic cells was of minimal consequence. These data suggest that species-specific TLR4/MD2 responses in stromal and epithelial compartments can alter the disease course. Studying C. burnetii infection in hTLR4/MD2-expressing mice will result in findings that are likely more readily applicable to human patients.
The N terminus of Yersinia pestis’ YscF masks YscF’s naturally occurring PAMP, inhibiting inflammation and allowing for colonization in vivo
Authors: O’Donnell Kyle Lee , Alvine Travis D , Osei-Owusu Patrick , Niles Matthew , Bradley David 
Published: January 2023

Abstract
Type III secretion (T3S) systems, common to many Gram- bacteria, act as a needle to deliver virulence factors directly into eukaryotic cells, often modulating host immunity. Multimers of YscF polymerize to form the surface-located T3S needle-like structure. We have previously shown that YscF has PAMP properties, acting as both a TLR2 and TLR4 agonist. We have also shown that modulation of this PAMP activity in vitro is located in the N terminus of YscF. We hypothesized that the N terminus of YscF contributes to Y. pestis survival within the eukaryotic host. We generated a 15 amino acid N terminal truncation of YscF (delta15YscF) expressed in Y. pestis. The truncation did not affect T3S system translocation. The delta15YscF Y. pestis strain was able to secrete Yops, albeit at a level lower than wild type (wt) Y. pestis. As expected, wt Y. pestis colonized the spleen and liver, whereas delta15YscF Y. pestis exhibited significantly impaired colonization in both organs. Mice infected with delta15YscF Y. pestis developed significantly more inflammation compared to wt Y. pestis. At 3 days p.i., delta15YscF spleen weights were significantly heavier and spleen inflammation was accompanied by a significant enhancement of macrophage and neutrophil migration compared to wt mice. These data support a role for the N terminus of YscF contributing to host bacterial clearance. Truncating the N terminus may result in a PAMP which is thereby unmasked and able to induce an inflammatory response.
Multi-step Th17 differentiation in response to segmented filamentous bacteria in the mouse intestine
Authors: Sano Teruyuki , Yang Yi , Diehl Gretchen , Chen Alessandra , Kaplan Daniel H , Littman Dan R 
Published: January 2023

Abstract
Th17 cells have significant roles in maintaining homeostasis and regulating host defense against various pathogens in our bodies. Our laboratory initially identified segmented filamentous bacteria (SFB) as a unique commensal that is sufficient for Th17 cell differentiation and promotion of Th17-dependent autoimmune diseases such as a mouse model of spontaneous arthritis. The molecular and cellular requirements of SFB-induced Th17 cell differentiation are still unclear. To understand the whole process of Th17 cells differentiation in vivo, we developed SFB-specific T cell receptor transgenic (7B8) mice. We can trace SFB-specific Th17 cell differentiation and response by transferring fluorescently-labeled 7B8 naïve T cells into SFB-gavaged host mice. Using this approach, we have elucidated the requirements for cytokines and antigen presenting cells (APCs) to understand the process of Th17 cell differentiation. Here, we describe that initial induction and expansion of Th17 cells occurs in mesenteric lymph nodes (MLN), and their subsequent migration to intestine is integrin β7-dependent. Although RORγt expression in Th17 cells is mainly dependent on IL-6 signaling in the MLN, IL-23R signaling also contributes to RORγt expression in Th17 cells in the ileum in the absence of IL-6. CD103+ CD11b+ APCs are not important for induction and initial expansion of SFB-specific Th17 cells in MLN, but play important roles in maintenance of SFB-specific Th17 cells in the ileum. Taken together, these results indicate that Th17 cell differentiation proceeds in multiple discrete stages.