Project description:We performed single-cell RNA sequencing (scRNA-seq) using the 10x Genomics platform to characterize pancreatic immune cell populations in germ-free (GF) and specific-pathogen-free (SPF) mice with cerulein-induced acute pancreatitis (AP). scRNA-seq analysis identified distinct neutrophil subpopulations influenced by gut microbiota presence. SPF mice showed enrichment of pro-inflammatory neutrophil clusters associated with increased neutrophil extracellular trap (NET) formation, whereas GF mice exhibited neutrophil subsets expressing reparative and protective signatures. Our data highlight the role of gut microbiota in shaping immune responses during AP.
Project description:Neutrophil infiltration around the pancreatic ducts has been found to be associated with type 2 autoimmune pancreatitis (AIP). However, the functional role and clinical importance of neutrophils migration on the progress of pancreatitis is not fully understood. Here, we found that neutrophil extracellular traps (NETs) are abundant around the pancreatic duct in type 2 AIP patients. Moreover, we observed the expression of TLR9 is higher in pancreatic ductal epithelial Cells (HPDEC) in type 2 AIP patients than in other pancreatic diseases. TLR9 acts as a NET-DNA receptor on HPDEC that senses extracellular DNA and subsequently activates the NF-κB pathway to attract neutrophils motility and induce NETs formation. In addition, the TLR9 antagonist hydroxychloroquine (HCQ) can effectively inhibit the activation of inflammatory pathways, reduce the migration of neutrophils and block the positive feedback mechanism, which can be used as a potential target drug for the clinical treatment of type 2 AIP.
Project description:Neutrophils, key players in the innate immune system, become activated following ischemic stroke. However, the influence of gut microbiota on neutrophil activation and its impact on inflammatory brain injury is not yet fully understood. In this study, we demonstrate that microbiota colonization in germ-free mice activates neutrophils and worsens disease outcomes. To investigate the phenotypic and molecular alterations in neutrophils, as well as their activity in stroke mice with either depleted or intact microbiota, we conducted a comparative proteomic analysis using liquid chromatography-based mass spectrometry. Our findings revealed that microbiota depletion leads to a downregulation of inflammatory proteins in circulating neutrophils and a reduction in neutrophil extracellular traps (NETs). A similar pattern was observed in neutrophils infiltrating the brain, accompanied by a decrease in infarct size and alleviated behavioral deficits.
Project description:This SuperSeries is composed of the following subset Series: GSE32542: Murine serum reactivity to common autoantigens in response to immunization with neutrophil extracellular traps GSE32543: Human and murine serum reactivity to specific histone posttranslational modifications in neutrophil extracellular traps Refer to individual Series
Project description:Background: Acute pancreatitis (AP) is a common severe digestive disorder, with severity linked to high-fat diets (HFD). HFD may exacerbate AP by promoting inflammation and altering gut microbiota. Astragalus polysaccharides (APS) possess anti-inflammatory properties, but it is unclear if APS supplementation can mitigate HFD's detrimental effects on AP by modulating gut microbiota. This study investigates the mechanisms by which APS improves HFD-induced AP exacerbation. In this study, C57BL/6 mice were fed HFD or a standard diet, with or without APS, for 12 weeks. AP was induced via intraperitoneal caerulein injection. Analyses included ELISA, Western blotting, histology, immunohistochemistry, immunofluorescence, single-cell RNA sequencing (scRNA-seq), 16S rRNA sequencing of gut microbiota, and short-chain fatty acid (SCFA) analysis to evaluate inflammation and cellular changes. Results: HFD significantly increased AP severity, indicated by elevated serum enzyme and pro-inflammatory cytokine levels, along with extensive pancreatic damage. Single-cell RNA sequencing (scRNA-seq) showed a notable rise in ICAM1+ neutrophils and activation of the NF-κB/necroptosis pathway in HAP mice. APS alleviated these effects by decreasing ICAM1+ neutrophil infiltration, downregulating the NF-κB pathway, and reducing necroptosis. Moreover, APS restored gut microbiota balance, significantly boosting Lactobacillus reuteri (L. reuteri) abundance and propionate (PA) levels. Treatments with L. reuteri and PA independently mitigated HFD-induced AP severity, indicating that APS's protective effects are microbiota-dependent. Conclusion: APS improves HFD-induced gut dysbiosis and intestinal barrier dysfunction by enriching L. reuteri and PA, effectively reducing AP exacerbation. Our findings highlight the gut-pancreas axis as a promising target for addressing AP severity.
Project description:Intracerebral hemorrhage (ICH) induces alterations in the gut microbiota composition, significantly impacting neuroinflammation post-ICH. However, the impact of gut microbiota absence on neuroinflammation following ICH-induced brain injury remain unexplored. Here, we observed that the gut microbiota absence was associated with reduced neuroinflammation, alleviated neurological dysfunction, and mitigated gut barrier dysfunction post-ICH. In contrast, recolonization of microbiota from ICH-induced SPF mice by transplantation of fecal microbiota (FMT) exacerbated brain injury and gut impairment post-ICH. Additionally, microglia with transcriptional changes mediated the protective effects of gut microbiota absence on brain injury, with Apoe emerging as a hub gene. Subsequently, Apoe deficiency in peri-hematomal microglia was associated with improved brain injury. Finally, we revealed that gut microbiota influence brain injury and gut impairment via gut-derived short-chain fatty acids (SCFA).
Project description:The apical-basal polarity of pancreatic acinar cells is essential for maintaining tissue architecture. However, the mechanisms by which polarity proteins regulate acinar pancreas tissue homeostasis are poorly understood. Here, we evaluate the role of Par3 in acinar pancreas injury and homeostasis. While Par3 loss in the mouse pancreas disrupts tight junctions, Par3 loss is dispensable for pancreatogenesis. However, with aging, Par3 loss results in low-grade inflammation, acinar degeneration, and pancreatic lipomatosis. Par3 loss also exacerbates pancreatitis-induced acinar cell loss, resulting in pronounced pancreatic lipomatosis and failure to regenerate. Moreover, Par3 loss in mice harboring mutant Kras causes extensive pancreatic intraepithelial neoplastic (PanIN) lesions and large pancreatic cysts. We also show that Par3 loss restricts injury-induced primary ciliogenesis. Significantly, targeting BET proteins enhances primary ciliogenesis during pancreatitis-induced injury and, in mice with Par3 loss, limits pancreatitis-induced acinar loss and facilitates acinar cell regeneration. Combined, this study demonstrates how Par3 restrains pancreatitis- and Kras-induced changes in the pancreas and identifies a potential role for BET inhibitors to attenuate pancreas injury and facilitate pancreas tissue regeneration.
Project description:Sterile tissue injury after stroke causes lymphocyte contraction in lymphoid tissues and may decrease circulating IgA-levels. Intestinal Peyer’s patches (PP) harbor large numbers of IgA+ B cell precursors and plasma cells. Whether and how tissue injury triggers PP-B cell death, thereby mediating IgA-loss, is unknown. We found decreased circulating IgA levels in stroke and myocardial infarction patients. Experimental stroke and myocardial infarction in mice phenocopied the human situation. Decreased plasma and fecal IgA were accompanied by rapid and macroscopic shrinkage of PP caused by substantial losses of PP-resident IgA+ precursors and plasma cells in mice. Tissue injury induced neutrophil activation endowed with the release of toxic neutrophil extracellular traps (NETs). Antibody-mediated or genetically- induced neutrophil loss, digestion of NETs, or inhibition of their release by the Gasdermin D blockade completely prevented lymphocyte loss and PP shrinkage. We also identified NETs in the plasma of stroke and myocardial infarction patients. Hence, tissue injury induces systemic NET-release, which might be targeted to maintain immune homeostasis at mucosal barriers.