bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sphingosine 1-phosphate is a harbinger of S. aureus invasion and activates host defense in epithelial barriers
Authors: Igawa Satomi , Choi Jae Eun , Wang Zhenping , Chang Yu-Ling , Wu Chia-Chi , Werbel Tyler , Ishida-Yamamoto Akemi , Di Nardo Anna 
Published: January 2023

Abstract

Background
Sphingosine 1-phosphate (S1P) is a bioactive lipid mediator generated in the skin when cell membrane or barrier components are damaged. S1P regulates diverse cell activities via S1P receptors (S1PR). Keratinocytes express S1PR1–5. Although it is known that S1PRs control keratinocyte differentiation, apoptosis and wound healing, S1PR functions in keratinocyte infections are not fully elucidated. We hypothesized that S1P and S1PR-axis in keratinocytes works as a biosensor for bacterial invasion.

Methods
The expression of S1PRs were studied by immunofluorescence and qPCR. Cytokine transcription and secretion were detected by qPCR and ELISA, respectively. siRNA and S1PR2 antagonist, JTE013, were used to test the different S1PR functions. The S1P synthesis was tested by ATP depletion assay and ELISA.

Results
We found a high epidermal S1PR1 and 2 expressions in human impetigo skin. In vitro, in normal human epidermal keratinocytes (NHEK), S. aureus bacterial supernatant not only induced S1P production but also increased S1PR2 transcription and TNFα, IL36γ, 6 and 8 transcriptions, confirming our in vivo observation. S1P directly increased NHEK IL36γ, TNFα and IL8 expression, but not IL6. In both, S1P and S. aureus bacterial supernatant treated NHEK, S1PR1 knock down reduced IL36γ, TNFα and IL8 transcription, while S1PR2 antagonist, JTE013, blocked their protein secretion.

Conclusions
We proved that, during infections, keratinocytes communicate the infection by sensing S1P release and respond to it using receptors S1PR1 and 2, releasing pro-inflammatory cytokines.
Perforin-2 dependent intracellular bacterial killing by skin γδ T cells
Authors: O’Neill Katelyn Elizabeth , Romero Laura , Fisher Eva , Garcia Denisse , Wikramanayake Tongyu , Pastar Irena , Tomic-Canic Marjana , Strbo Natasa 
Published: January 2023

Abstract
The skin serves as a first line of defense against physical, chemical insults and a vast array of potentially pathogenic microorganisms. Gamma delta (γδ) T cells are a subset of unconventional T cells residing in the skin that play a critical role in protection against bacterial infections, malignancies and in maintaining keratinocyte homeostasis. To characterize the mechanisms governing γδ T cell cytotoxic responses against intracellular pathogens, such as Methicillin Resistant Staphylococcus Aureus(MRSA), we investigated the role of Perforin-2 (P-2), a novel member of the pore-forming family of innate immune proteins.
Skin cells (epidermis and dermis) were separated enzymatically from C57/Bl6 WT and P2 deficient (−/−) mouse dorsal skin using collagenase D. Cells were stained with anti-TCR γδ antibodies, sorted, infected with MRSA and used for intracellular gentamicin protection assays or electron microscopy analysis. γδ T cell lysates were plated and colony forming unit (CFU) count was determined. Frozen sections of dorsal mouse skin were used for immunofluorescence analysis.
We found that P-2 deficient γδ T cells infected intracellularly with MRSA are unable to kill MRSA. Using electron microscopy we confirmed that MRSA resides within γδ T cells. In P2 −/− mice we observed a lower number of γδ T cells in the skin at steady state. Upon transcutaneous MRSA infection (109 CLP 153), in the absence of P2 (−/−), all mice die. We observed that P2 (−/−) γδ T cells migrate more rapidly in the blood than γδ T cells expressing P2. In summary, we showed for the first time that skin γδ T cells can directly kill an intracellular pathogen (MRSA) through a P-2 dependent mechanism. Our data confirms that Perforin-2 is a novel γδ T cell effector molecule in the skin.
Essential Roles of CCL2-CCR2 and C5a-C5aR1 Pathways in irritant Contact Dermatitis
Authors: Shibuya Rintaro , Kitoh Akihiko , Kabashima Kenji 
Published: January 2023

Abstract
Cutaneous immune response induced by epithelial cell stress induces represents the first line defense against pathogens. We have reported that basophils play a pivotal role in the skin inflammation caused by irritants. However, it has not been fully understood how they accumulate in the skin. Previous studies have shown that epithelial cell damage induces complement activation in organs such as the lung and the kidney, implicating a possible involvement of the complement activation in the immune response caused by epithelial cell stress in the skin. Thus, we investigated the mechanism of basophil recruitment to the skin focusing on the complement system.
Topical application of the surfactant sodium dodecyl sulfate (SDS) onto murine ears induced basophil-dependent skin inflammation. Among chemokines which were up-regulated by SDS application, we found that CCL2-CCR2 axis was critical for basophil recruitment to the skin. Here, CCR2 on basophils was dispensable and CCR2 on radioresistant cells was essential.
Finally, we evaluated the contribution of complement system to SDS-induced basophil recruitment to the skin. SDS application induced C3 and C5a production in the skin, suggesting a complement activation in the skin. We evaluated whether C3 and C5a are involved in SDS-induced basophil recruitment by using C3 deficient mice and C5a receptor 1 deficient mice. The result showed that C3 deficiency or C5aR1 deficiency significantly attenuated SDS-induced basophils accumulation. By contrast, SDS-induced CCL2 production in these mice was comparable to WT mice.
Collectively, our data suggest that both CCL2-CCR2 and C5a-C5aR pathways are essential to the SDS-induced innate immune response in the skin by modulating basophil recruitment.
Noncanonical Inflammasome-Induced release of Alarmins during Sepsis
Authors: Russo Ashley Jean , Menoret Antoine , Duduskar Shivalee , Rabinovich Gabriel , Deshmukh Sachin D , Vella Anthony T , Rathinam Vijay 
Published: January 2023

Abstract
Sepsis is a life-threatening disease caused by the immune system’s response to infection that results in excessive inflammation, organ damage and often death. In fact, sepsis is the leading cause of death in intensive care units and is responsible for more than 250,000 deaths every year in the USA. Activation of inflammatory caspases, such as caspase-11 by lipopolysaccharide (LPS) from Gram-negative bacteria, is a key mechanism of innate immune defense against infection. Intracellular sensing of LPS by caspase-11 results in pyroptosis, maturation of caspase-1, IL-1β and IL-18 and unconventional secretion of intracellular proteins that lack a leader sequence for conventional secretion via endoplasmic reticulum-Golgi route. These proteins can act as alarmins or damage associated molecular patterns (DAMPs) to regulate the inflammatory response and therefore play an important role during infectious diseases. However, caspase-11-dependent release of alarmins and DAMPs following noncanonical inflammasome activation is poorly characterized. Using a proteomics approach involving ProteomeLab’s PF2D fractionation system followed by mass spectrometry, we have profiled several new alarmins released in a caspase-11 dependent manner following Gram-negative bacterial infection. By employing various mutant mice and cells, we have defined the molecular and cellular mechanisms underlying the release of a candidate alarmin as a consequence of noncanonical inflammasome activation in vitro and in vivo. Importantly, our in vivo studies demonstrate a critical role for this alarmin in LPS shock. Overall, these findings provide new insights into potential biomarkers and therapeutic targets for blocking the lethal inflammation in sepsis.
Development of a humanized mouse model for functional testing of biomaterial fibrosis
Authors: Greiner Dale L , Doloff Joshua C , Sadraei Atieh , Farah Shady , Brehm Michael A , Shultz Leonard D , Langer Robert , Anderson daniel G 
Published: January 2023

Abstract
Implanted biomedical devices reside within tens of millions of patients in the United States alone, and are involved in millions of new surgeries every year. They comprise a major component of modern medicine and are essential for many clinical applications ranging from hip/knee replacement, tissue repair/reconstruction, controlled release, sensing, and cell transplantation. Limiting therapeutic performance and lifespan, immune-mediated foreign body rejection results in sequestration behind dense layers of fibrotic scar tissue. Deeper understanding of wildtype rodent and non-human primate foreign body responses was leveraged to generate a variant of humanized mice that is capable of recapitulating fibrosis following implantation. Cellular and cytokine responses were also determined with multiple biomaterials—hydrogel alginate and polymers polystyrene and polydimethylsiloxane (PDMS), as well as across multiple implant sites. Innate immune macrophages were verified as essential in the development of fibrosis in this model, and that they were capable of crosstalk with mouse fibroblasts for collagen matrix deposition. Cytokine and cytokine-receptor array analysis confirmed core signaling in the fibrotic cascade. Lastly, high-resolution microscopy coupled with multiplexed antibody-capture analyses revealed spatial resolution of rejection responses. This model allows us to investigate dynamic human immune cell interactions with implantables, and offers a surrogate pre-clinical diagnostic for screening biomaterial immunogenicity.
Microglial antigen presentation is required for antigen specific CD8 T cell infiltration to the brain parenchyma following CNS viral challenge
Authors: Goddery Emma , Malo Courtney , Jin Fang , Hansen Michael , Fryer John , Pavelko Kevin , Johnson Aaron 
Published: January 2023

Abstract
Cytotoxic T cell infiltration into the central nervous system (CNS) is required for clearance of pathogen or tumor. Whether microglia, the resident innate immune cells of the brain, are involved in orchestrating CD8 T cell infiltration of the brain in an antigen dependent manner remains to be elucidated. We hypothesized that antigen presentation by major histocompatibility complex (MHC) class I molecules expressed by microglia is required to orchestrate antigen specific CD8 T cell infiltration into the brain parenchyma. To test this hypothesis, we generated a novel tamoxifen-inducible microglial MHC class I conditional knockout mouse (CX3CR1-creERT2H-2Kb cKO). In these mice, administration of tamoxifen mediates deletion of the H-2Kbmolecule in cells expressing CX3CR1. Short-lived peripheral CX3CR1+ cells repopulate within 4–6 weeks after tamoxifen treatment and restore expression of H-2Kb, leaving only long-lived microglia deficient for MHC class I. We challenged these mice with intracranial infection of Theiler’s murine encephalomyelitis virus expressing the model antigen ovalbumin (TMEV-OVA) to assess antigen specific CD8 T cell responses within the brain parenchyma. In microglia MHC I cKO mice, the frequency of brain infiltrating OVA-specific CD8 T cells was attenuated while the frequency of intravascular OVA-specific CD8 T cells was increased when compared to cre− littermate controls. These results suggest that microglial antigen presentation is important for antigen specific CD8 T cell infiltration into the brain parenchyma. These studies directly address the critical role of microglial MHC class I on antigen specific CD8 T cell responses to an in vivo neuroinflammatory insult.
The host E3-ubiquitin ligase TRIM6 plays an important role in balancing protective innate antiviral immunity and damaging inflammation
Authors: Rajsbaum Ricardo , Aguilera-Aguirre Leopoldo , Hage Adam 
Published: January 2023

Abstract
The host antiviral innate immune response involves activation of multiple signaling pathways that culminate in the production of type I interferons (IFN-I) and inflammatory cytokines, which together control virus infections. However, excessive cytokine production can result in exacerbated disease. To strike the right balance, these signaling pathways are regulated by different molecular processes, including the ubiquitin (Ub) system. We recently reported that the E3-Ub ligase TRIM6 catalyzes the synthesis of unanchored K48-linked poly-Ub chains, which are not covalently attached to any protein, and promote antiviral IFN-I responses by activating the IKKɛ kinase. Two different highly pathogenic viruses, Nipah (NiV) and Ebola (EBOV), hijack TRIM6 to promote virus replication through mechanisms that involve both covalent and unanchored Ub. This indicates that host antiviral factors can have direct pro-viral functions. Consistent with this notion, EBOV replication is decreased in the lungs of TRIM6 knockout mice (Trim6−/−) upon intranasal administration. In contrast, TRIM6 plays a protective role against Influenza (IAV), via the IFN-I pathway, but can exacerbate disease via induction of chemokines and infiltration of inflammatory cells. Although Trim6−/− mice have increased IAV titers, they also show reduced signs of pathology and reduced neutrophil infiltration in the lungs. Phosphorylation of AKT is impaired in Trim6−/− cells resulting in decreased CXCL1 expression, a well-known neutrophil chemo-attractant. These results suggest that TRIM6 regulates multiple innate immune pathways to balance protective and excessive inflammatory responses, and viruses have adapted to hijack TRIM6 to enhance their replication
Early host responses to cattle gastro-intestinal parasite Ostertagia ostertagi
Authors: Bakshi Mariam , Tuo Wenbin , Zarlenga Dante 
Published: January 2023

Abstract
Ostertagia ostertagi is a gastrointestinal parasite of cattle that has a huge economic impact on the US cattle industry. With the rise in drug resistance among nematodes, vaccination is advanced as the most cost-effective alternative; however, nematode vaccines have met with lackluster results thus far. Thus, understanding host-parasite interactions is a critical step for controlling parasite transmission. Reports show that a primary O. ostertagi infection in cattle does not elicit the classic Th2 (anti-inflammatory) paradigm suggesting that an overall mixed response (mixture of Th1, Th2 and other types of Th) may dominate in the absence of a protective response. Little is known about the host innate immune pathways to which O. ostertagi is subjected. This research investigates the early onset of host immune response during the infection by determining the; 1) kinetic responses of immune mediated genes within peripheral blood mononuclear cells using quantitative (q) real time (RT) PCR; and 2) influence of O. ostertagi excretory secretory molecules on host innate immune cells i.e., macrophages, by in-vitro cell activation assays followed by qRT-PCR and immune-cytochemistry. Results show that upon progression of the disease, gene expression of a subset of Toll-like receptor genes increased, indicating active involvement of different cellular immune responses. Additionally, morphological changes in macrophages coupled with transcriptional changes in TNFα and TGFβ supported classical signs of cell activation. These results demonstrate early initiation of host immune responses during a parasitic infection and help further elucidate the complex and intimate relationship between O. ostertagi and its bovine host.
Activation of AMPK restricts Zika virus replication in endothelial cells by potentiating antiviral response and inhibiting viral-induced glycolysis
Authors: Kumar Ashok , Singh Sneha , Singh Pawan , Giri Shailendra 
Published: January 2023

Abstract
Viruses are known to perturb host cellular metabolism to enable their replication and spread. However, studies examining Zika virus (ZIKV) infection and metabolism are limited. Here, using primary human retinal vascular endothelial (HRvEC) cells and HUVEC cell line, we investigated the role of AMPK, a master regulator of energy metabolism, in response to ZIKV challenge. ZIKV infection caused a time-dependent reduction in the phosphorylation of AMPK and its downstream target ACC. Pharmacological activation of AMPK using AICAR or metformin attenuated ZIKV replication, and similar findings were observed using GSK621, a specific activator of AMPKα. This phenomenon was reversed by incubation of cells with an AMPK inhibitor, compound C. Lentivirus-mediated knockdown of AMPK and the use of AMPK−/− MEFs further supporting the notion that AMPK restricts ZIKV replication. Interestingly, AMPK activation potentiated the expression of genes with antiviral properties (e.g., IFNs, OAS2, ISG15, MX1) and inhibited inflammatory mediators (e.g., TNFα, CCL5). Bio-energetic analysis revealed that ZIKV infection evoked a glycolytic response, as evidenced by elevated ECAR (extracellular acidification rate) levels and increased expression of key glycolytic genes (GLUT1, HK1, TPI, MCT4); AICAR treatment reduced this response. Consistent with this, 2-deoxyglucose (2DG), an inhibitor of the glycolysis, augmented AMPK activity, and attenuated ZIKV replication. Collectively, our study demonstrates that AMPK activation restricts ZIKV replication by promoting an antiviral responses and inhibiting ZIKV-induced glycolysis in endothelial cells. AMPK signaling thus represents a new potential antiviral target for ZIKV infections.
Listeria hijacks host cell mitophagy to evade killing through a novel mitophagy receptor
Authors: Qian Youcun 
Published: January 2023

Abstract
Mitophagy, a selective form of autophagy, plays a critical role in eliminating damaged or excessive mitochondria during cell homeostasis or challenge to maintain the organelle quality and function. Listeria monocytogenes (L.m) is an intracellular pathogen of humans and animals, and an important and widely used model organism to study bacterial pathogenesis and host defense. It is still unknown if bacterial pathogens can induce host cell mitophagy. We made use of an L.m model system to show that intracellular bacterial pathogens induced host mitophagy in macrophages. Through a mitophagy inhibitor and a mitophagy promoter, we demonstrated that L.m-induced mitophagy provided a survival advantage of the bacterial pathogen. We further identified an LC3-interacting region (LIR)-containing protein as a novel mitophagy receptor for L.m-induced mitophagy. Consistent with the results of the mitophagy inhibitor, deficiency of the mitophagy receptor resulted in much reduced L.m titers both in macrophages in vitro and in mice in vivo. Thus our study discovers a previously unappreciated strategy by pathogens to hijack a host cellular homeostasis system for their survival. Mitophagy inhibitor or targeting mitophagy machinery may be useful for developing efficient therapeutic strategies against infections.
Inhibitory effect of short-chain fatty acids on the induction of nitric oxide by Staphylococcus aureus lipoproteins in macrophages
Authors: Han Seung Hyun , Park Jeong Woo , Kim Hyun Young , Kim Min Geun , Jeong Soyoung , Yun Cheol-Heui 
Published: January 2023

Abstract
Staphylococcus aureus is a Gram-positive bacterial pathogen that can cause severe inflammation often resulting in life-threatening diseases. Lipoproteins of S. aureus are a major virulence factor to induce excessive inflammatory mediators such as nitric oxide (NO) in macrophages. Short-chain fatty acids (SCFAs) such as butyrate, propionate, and acetate are commensal bacteria-derived metabolites in the gut that are known to have anti-inflammatory effects. In this study, we investigated the effects of SCFAs on S. aureus lipoprotein (Sa.LPP)-induced NO production in mouse macrophages. Butyrate and propionate, but not acetate, inhibited Sa.LPP-induced production of NO in RAW 264.7 cells and mouse bone marrow-derived macrophages. Butyrate and propionate inhibited Sa.LPP-induced expression of inducible NO synthase (iNOS). However, acetate did not show such effect under the same conditions. Furthermore, butyrate and propionate, but not acetate, inhibited Sa.LPPinduced activation of NF-κB, expression of IFN-β, and phosphorylation of STAT1, which are essential for inducing transcription of iNOS in macrophages. In addition, butyrate and propionate induced histone acetylation at lysine residues in the presence of Sa.LPP in RAW 264.7 cells. Moreover, Sa.LPP-induced NO production was decreased by histone deacetylase (HDAC) inhibitors. Collectively, these results suggest that the SCFAs butyrate and propionate attenuate the inflammatory responses caused by S. aureus lipoproteins through the inhibition of NF-κB, IFN-β/STAT1, and HDAC, resulting in attenuated NO production in macrophages.
Leishmania major degrades CXCL1 to subvert host immune responses
Authors: Gurung Prajwal , Yorek Matthew , Poudel Barun , Mazgaeen Lalita 
Published: January 2023

Abstract
Leishmaniasis is a global health problem with an estimated report of 2 million new cases every year. Innate immune system plays a central role in controlling L. major infection by initiating a signaling cascade that results in production of pro-inflammatory cytokines and recruitment of both innate and adaptive immune cells. Upon infection with L. major, CXCL1 is produced locally and plays an important role in the recruitment of neutrophils and macrophages to the site of infection. Herein, we report that L. major specifically targets murine CXCL1 for degradation and this allows L. major to establish infection in the host. The degradation of CXCL1 is not dependent on host factors because L. major can directly degrade recombinant CXCL1 in a cell-free system. Using mass spectrometry, we have identified that the L. major protease cleaves at the C-terminal end of murine CXCL1. Finally, our data suggest that L. major metalloproteases are involved in the direct degradation of CXCL1. Currently, we are testing the hypothesis that the peptide spanning the cleavage site can be used to inhibit L. major protease activity and pathogenesis.
Functional elucidation of miR-494 in modulation of HCV infection
Authors: Lin Tsun-Mei , Eng Hock-Liew 
Published: January 2023

Abstract
Hepatitis C virus (HCV) infection is considered one of the most important causes of chronic liver diseases due to major alteration in the cross-talk between hepatic cells and immune cells. Many reports have shown that the proteins of HCV might interact with the genes to regulate cellular pathways and miRNA expression contribute to the pathogenesis of liver diseases. In this study, the profiling of miRNAs in hepatocytes transfected with HCV structure proteins was compared by microarray analysis. MiR-494 was significantly decreased in E1 transfected HepG2 cells, but increase in core-transfected or E2-transfected HepG2 cells. However, the expression and activation of TLR7/8 and inflammatory cytokines were dramatically enhanced by E1 protein. Interferon treatment was demonstrated to enhance miR-494 expression but reduced TLR7 and TLR8 signaling in E1 protein transfected HepG2. MiR-494 was proposed to regulate TLR7 and TLR8 expression as confirmed by directly targeting 3′-UTR of TLR7 and TLR8. However, the molecular functions of the involvement of miR-494 in HCV infected hepatocytes remained to be elucidated. The expression of miR-494 in serum samples of HCV infected patients was increased as compared with corresponding controls (mean ± SEM: 23,100 ± 9,700 vs.32.5± 14.2, p&lt; 0.001). Determined through analysis using XTT and transwell assays, the HCV core-overexpression and miR-494 restoration were demonstrated to significantly enhance HepG2 proliferation and migration, In conclusion, our results have shown that HCV structure proteins might play a role in the pathogenesis of chronic hepatic diseases via interaction with miRNA-494 to modulate TLR7/8 expression.