Project description:B cells expand during the recovery after DSS-induced colonic inflammation. To investigate if a specific subtype is expanding and to analyse the transcriptional profile of these cells a transcriptional analysis on single cell level was carried out. In detail, B cells were isolated from the colon of mice on day 0 (no treatment) or day 14 (recovery) after 7 days of DSS treatment by flow cytometric sorting and analyzed by 10X sequencing.
Project description:BACKGROUND: Peroxisome proliferator-activated receptor g (PPAR g) is a nuclear receptor whose activation has been shown to modulate macrophage and epithelial cell-mediated inflammation. The objective of this study was to use a systems approach for investigating the mechanism by which the deletion of PPAR g in T cells modulates the severity of dextran-sodium sulfate (DSS)-induced colitis, immune cell distribution and global gene expression. METHODS: Wild-type (WT) or PPAR g flfl; CD4 Cre+ (CD4cre) mice in a C57BL/6 background were challenged with 2.5% DSS in their drinking water for 0, 2, or 7 days. Mice were scored on disease severity both clinically and histopathologically. Flow cytometry was used to assess lymphocyte and macrophage populations in the blood, spleen, and mesenteric lymph nodes (MLN). Global gene expression in colonic mucosa was profiled using Affymetrix microarrays. RESULTS: Both disease severity and inflammation-related body weight loss were accelerated by the deficiency of PPAR g in T cells. Examination of colon histopathology revealed significantly greater epithelial erosion, leukocyte infiltration, and mucosal thickening in the CD4cre mice on day 7. CD4cre mice had more CD8+ T cells than wt mice and fewer CD4+FoxP3+ regulatory T cells (Treg) and IL10+CD4+ T cells in blood and MLN, respectively. Transcriptomic profiling revealed around 3000 genes being transcriptionally altered as a result of DSS challenge in CD4cre mice. These included up-regulated adhesion molecules on day 7 and proinflammatory cytokines interleukin-6 (IL-6) and IL-1b, and suppressor of cytokine signaling 3 (SOCS-3) mRNA expression. CONCLUSIONS: These findings suggest that T cell PPAR g down-regulates inflammation during DSS colitis by inhibiting colonic expression of inflammatory mediators and increasing MLN Treg. Colonic mucosa from wt and CD4cre mice were sampled at 0 (no DSS), 2, and 7 days of DSS-induced experimental colitis
Project description:The lack of suitable animal models reflecting chronically relapsing inflammation and tissue remodeling have hindered fibrosis research in inflammatory bowel diseases (IBD). This study investigated changes in connective tissue in a chronic murine model using different cycles of dextran sodium sulphate (DSS) to mimic the relapsing nature of the disease. We used whole gene expression arrays to study differences in colonic gene expression levels between acute and more chronic DSS colitis, Acute and chronic relapsing colonic inflammation was induced in C57BL6 female mice using several cycles of exposure to DSS in drinking water, followed by recovery phases. Total RNA, extracted from snap frozen colon from five mice per condition was used to analyze mRNA expression via Affymetrix Mouse Gene 1.0 ST arrays.
Project description:We determined changes in enhancer chromatin that occur during colonic inflammation, found that dynamic chromatin regions are enriched for HNF4A binding motirfs, and then measured HNF4A binidng by ChIP-seq in each condition. Examination of H3K27ac histone modification in normal and DSS-treated colon, examination of HNF4A binding by ChIP-seq in normal and DSS-treated colon epithelium
Project description:The mucosal epithelium plays a key role in regulating immune homeostasis. Dysregulation of epithelial barrier function is associated with mucosal inflammation. Expression of claudin-2, a pore-forming tight junction protein, is highly upregulated during inflammatory bowel disease (IBD) and, due to its association with epithelial permeability, has been postulated to promote inflammation. Furthermore, claudin-2 also regulates colonic epithelial cell proliferation and intestinal nutrient absorption. However, the precise role of claudin-2 in regulating colonic epithelial and immune homeostasis remains unclear. Here, we demonstrate, using Villin-Claudin-2 transgenic (Cl-2TG) mice, that increased colonic claudin-2 expression unexpectedly protects mice against experimentally induced colitis and colitis-associated cancer. Notably, Cl-2TG mice exhibited increased colon length and permeability as compared with wild type (WT) littermates. However, despite their leaky colon, Cl-2TG mice subjected to experimental colitis were immune compromised, with reduced induction of TLR-2, TLR-4, Myd-88 expression and NF-kB and STAT3 activation. Most importantly, colonic macrophages in Cl-2TG mice exhibited an anergic phenotype. Claudin-2 overexpression also increased colonocyte proliferation and provided protection against colitis-induced colonocyte death. Taken together, our findings have revealed a critical role of claudin-2 in regulating colonic homeostasis, suggesting novel therapeutic strategies for inflammatory conditions of the gastrointestinal tract. 8-10 weeks old male Villin-Claudin-2 transgenic mice and WT littermates were provided either normal drinking water (control) or Dextran Sodium Sulfate (DSS: 4% w/v) for 10 days. 3 replicates each.
Project description:BACKGROUND: Peroxisome proliferator-activated receptor g (PPAR g) is a nuclear receptor whose activation has been shown to modulate macrophage and epithelial cell-mediated inflammation. The objective of this study was to use a systems approach for investigating the mechanism by which the deletion of PPAR g in epithelial cells modulates the severity of dextran-sodium sulfate (DSS)-induced colitis, immune cell distribution and global gene expression. RESULTS: The deficiency of PPAR g in epithelial cells does not significantly affect disease activity or body weight but worsens colon histopathlogy. WT mice have greater CD4+IL10+ T cells and fewer MHC II+ macrophages in mesenteric lymph nodes. Global gene expression analysis reveals greater changes after 7 days of DSS challenge (compared to 2 days). Colonic mucosa from VC- (WT) and VC+ (PPARg knock-out in epithelial cells) mice were sampled at 0 (no DSS), 2, and 7 days of DSS-induced experimental colitis
Project description:Nlrp6-/- lamina propria Ly6C-hi monocytes in response to AOM/DSS have deficient TNFα production, but increased production of other pro-inflammatory cytokines as compared to WT NLRP6 is a member of the Nod-like receptor family, whose members are involved in the recognition of microbes and/or tissue injury. NLRP6 was previously demonstrated to regulate the production of IL-18 and is important for protecting mice against chemically-induced intestinal injury and colitis-associated colon cancer. However, the cellular mechanisms by which NLRP6 reduces susceptibility to colonic inflammation remain unclear. Here, we determined that NLRP6 expression is specifically upregulated in Ly6Chi inflammatory monocytes that infiltrate into the colon during dextran sulfate sodium (DSS)-induced inflammation. Adoptive transfer of WT Ly6Chi inflammatory monocytes into Nlrp6-/- mice was sufficient to protect them from mortality, significantly reducing intestinal permeability and damage. NLRP6-deficient inflammatory monocytes were specifically defective in TNFα production, which was important for reducing DSS-induced mortality and dependent on autocrine IL-18 signaling by inflammatory monocytes. Our data reveal a previously unappreciated role for NLRP6 in inflammatory monocytes, which are recruited during intestinal injury to promote barrier function and limit bacteria-driven inflammation. This study also highlights the importance of early cytokine responses, particularly NLRP6-dependent and IL-18-dependent TNFα production in preventing chronic dysregulated inflammation. Ly6Chi monocytes were sorted from lamina propria of WT or Nlrp6-/- mice at day 10 of AOM/2%DSS. RNA was extracted and hybridized to the mouse 2.1 ST array.
Project description:To investigate the detailed molecular mechanisms for the regulatory role of HIF-2α in experimental colitis, microarray gene expression analysis was performed on colon RNA isolated from 6- to 8-week-old Hif-2αF/F, Hif-2αlΔIE mice treated with 3%DSS for 3 days. Background & Aims: Hypoxic inflammation is characterized by decreased oxygen tension in inflammatory foci, and is a notable feature in inflammatory bowel disease (IBD). Hypoxic response is mediated by transcription factors hypoxia-inducible factor (HIF)-1α and HIF-2α, both of which are highly induced in IBD. HIF-1α is a protective factor that limits intestinal barrier dysfunction during inflammation. However, the role of HIF-2α has not been assessed in hypoxic inflammation and IBD. Methods: A hypoxia reporter mouse model was used to test the presence of hypoxia and HIF-2α in dextran sulfate sodium (DSS) and Citrobacter rodentium (C.rod)-induced colitis. The role of HIF-2α in these mouse models of colitis was further assessed in mice with an intestinal epithelium-specific gain- and loss-of-function of HIF-2α. Results: Induction of hypoxia and HIF-2α was confirmed in both murine experimental colitis models and human IBD samples. Disruption of HIF-2α attenuated colonic inflammation whereas stabilization of HIF-2α potentiated inflammation in mouse models of colitis. Interestingly, intestine specific overexpression of HIF-2α but not HIF-1α leads to spontaneous colitis and premature death in mice. Further mechanistic analysis showed that HIF-2α is a driver for pro-inflammatory response and is critical regulator of intestinal epithelial-derived tumor necrosis factor (TNF)-α. Blocking TNF-α completely ameliorated HIF-2α potentiated intestinal inflammation. Conclusions: These data demonstrate that HIF-2α is a critical transcription factor essential in intestinal epithelium elicited inflammatory response. Global gene expression profiling in colon RNAs isolated from 7-week-old Hif-2αF/F (n=6, Shah 007) and Hif-2αΔIE (n=5, Shah 008).
Project description:Mature myeloid cells play a crucial role in the pathogenesis of Crohn disease (CD) but the molecular players that regulate their functions in CD are not fully characterized. Here we show that Trim33 mRNA level is decreased in CD patient’s blood monocytes and characterize TRIM33 functions in monocytes during dextran sulfate sodium (DSS) induced colitis. Mice deleted for trim33 only in mature myeloid cells (Trim33-/- mice) display an impaired resolution of colonic inflammation. This deficiency is associated with an increased number of blood and colon neutrophils and monocytes and a decreased number of colonic macrophages. In accordance, Trim33-/- monocytes are less competent that wild type monocytes for recruitment and differentiation into macrophages at the inflammatory site. Furthermore, during resolution of DSS-induced colitis, Trim33-/- colonic macrophages display an impaired M1/M2 switch and express a low level of membrane bound TNFα known to regulate resolution of inflammation. Altogether, these results show an important role of TRIM33 in monocytes/macrophages during the resolution of DSS-induced colonic inflammation and pinpoint TRIM33 as a novel Crohn disease biomarker and as a potential therapeutic target.
Project description:Background and Aims. Dendritic cells (DCs) play a pivotal role in maintaining immunological homeostasis by orchestrating innate and adaptive immune responses via migration to inflamed sites and the lymph nodes (LNs). Plasmacytoid DCs (pDCs) have been reported to accumulate in the colon of inflammatory bowel disease (IBD) patients and dextran sulfate sodium (DSS)-induced colitis mice. However, the role of pDCs in the progression of colonic inflammation remains unclear. Methods. 80 compounds in natural medicines were searched for inhibitors of pDC migration using bone marrow-derived pDCs (BMpDCs) and conventional DCs (BMcDCs). BALB/c mice were given 3% DSS in the drinking water for 7 days to induce acute colitis. Compounds, which specifically inhibited pDC migration, were administrated into DSS-induced colitis mice. Results. Astragaloside IV (As-IV) and oxymatrine (Oxy) suppressed BMpDC migration but not BMcDC migration. In DSS-induced colitis mice, the number of pDCs was markedly increased in the colonic lamina propria (LP), and the expression of CCL21 was obviously observed in colonic isolated lymphoid follicles (ILFs). As-IV and Oxy reduced symptoms of colitis and the accumulation of pDCs in colonic ILFs but not in the colonic LP. Moreover, in a BMpDC adoptive transfer model, BMpDC migration to colonic ILFs was significantly decreased by treatment with As-IV or Oxy. Conclusion. pDCs accumulated in the colon of DSS-induced colitis mice, and As-IV and Oxy ameliorated DSS-induced colitis by suppressing pDC migration to colonic ILFs. Accordingly, the selective inhibition of pDC migration may be a potential therapeutic approach for treating colonic inflammatory diseases.