Project description:Background; MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. MUC2 homo-oligomerizes intracellularly into large secreted polymers which give mucus its viscous properties. The inflammatory bowel disease (IBD) ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, whereas goblet cells and the mucus layer are increased in the other major inflammatory bowel disease, Crohnâs disease. Methods and Findings; By murine N-ethyl-N-nitrosourea-mutagenesis we identified two distinct non-complementing missense mutations in Muc2 exons encoding N- and C-terminal homo-oligomerization domains causing an ulcerative colitis-like phenotype. Both strains developed mild spontaneous distal intestinal inflammation, chronic diarrhea, rectal bleeding and prolapse, increased susceptibility to acute and chronic colitis induced by a luminal toxin, aberrant Muc2 biosynthesis, smaller goblet cell thecae (less stored mucin) and a diminished mucus barrier. Enhanced local production of IL-1beta, TNF-alpha and IFN-gamma was seen in the distal colon. The number of leukocytes within mesenteric lymph nodes was increased five-fold and leukocytes cultured in vitro produced both Th1 and Th2 cytokines (IFN-gamma, TNF-alpha and IL-13). Intestinal permeability was increased and the luminal bacterial flora were more heavily coated with immunoglobulin as occurs in IBD. This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis and wound repair. Expression of mutated Muc2 oligomerization domains in vitro demonstrated that aberrant Muc2 oligomerization underlies the ER stress. These models show that mutations in Muc2 oligomerization domains can lead to aberrant assembly of the Muc2 complex leading to ER stress, a depleted mucus barrier and intestinal inflammation. In ulcerative colitis we demonstrate similar accumulation of non-glycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in non-inflamed intestinal tissue. Conclusions; The observations that mucin misfolding and ER stress lead directly to intestinal inflammation and that ER stress and goblet cell pathology occur in ulcerative colitis suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of colitis. Experiment Overall Design: 3 individual mice from the Eeyore, Winnie or Wild-type strains were compared as groups. An Affymetrix ID was compared between groups if the ID was Present within two of the three mice within each grouping. IDs were compared by calculating the log2 of Group One average signal divided by Group 2 average signal.

Project description:Background MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. MUC2 homo-oligomerizes intracellularly into large secreted polymers which give mucus its viscous properties. The inflammatory bowel disease (IBD) ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, whereas goblet cells and the mucus layer are increased in the other major inflammatory bowel disease, Crohn’s disease. Methods and Findings By murine N-ethyl-N-nitrosourea-mutagenesis we identified two distinct non-complementing missense mutations in Muc2 exons encoding N- and C-terminal homo-oligomerization domains causing an ulcerative colitis-like phenotype. Both strains developed mild spontaneous distal intestinal inflammation, chronic diarrhea, rectal bleeding and prolapse, increased susceptibility to acute and chronic colitis induced by a luminal toxin, aberrant Muc2 biosynthesis, smaller goblet cell thecae (less stored mucin) and a diminished mucus barrier. Enhanced local production of IL-1beta, TNF-alpha and IFN-gamma was seen in the distal colon. The number of leukocytes within mesenteric lymph nodes was increased five-fold and leukocytes cultured in vitro produced both Th1 and Th2 cytokines (IFN-gamma, TNF-alpha and IL-13). Intestinal permeability was increased and the luminal bacterial flora were more heavily coated with immunoglobulin as occurs in IBD. This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis and wound repair. Expression of mutated Muc2 oligomerization domains in vitro demonstrated that aberrant Muc2 oligomerization underlies the ER stress. These models show that mutations in Muc2 oligomerization domains can lead to aberrant assembly of the Muc2 complex leading to ER stress, a depleted mucus barrier and intestinal inflammation. In ulcerative colitis we demonstrate similar accumulation of non-glycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in non-inflamed intestinal tissue. Conclusions The observations that mucin misfolding and ER stress lead directly to intestinal inflammation and that ER stress and goblet cell pathology occur in ulcerative colitis suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of colitis. Keywords: Single gene, multiple mutant comparison

Project description:Background: MicroRNAs (miRNAs) acting as negative regulators of gene expression are differentially expressed in intestinal tissues of patients with inflammatory bowel disease (IBD). Assessing the functional role of miRNAs in murine models of colitis facilitates elucidating the role of specific miRNAs in human IBD. The aim of this study was to determine the miRNA signature of murine models of colitis and to assess the influence of miR-21 on intestinal inflammation. Methods: miRNAs expression was accessed by microarray for acute and chronic murine model of colitis induced by DSS or TNBS. miR-21-deficient mouse and littermates controls were assessed in the standard DSS, TNBS and CD4+ T cell transfer models of colitis. RNAs of mouse colon and CD4+CD45RBHigh cells were analyzed by miRNA and mRNA microarray, and quantitative RT-PCR. Th1 polarization was accessed by flow-cytometry and ELISA. Results: Alterations of in miRNAs expression were identified for acute and chronic DSS colitis and TNBS colitis, receptively. The Expression of miRs-21, -142-3p and -223 was were distinct between DSS and TNBS models while overlap of numerous miRNAs was seen. Importantly, miRs-19b, -192 and -215, that are decreased in IBD, were significantly decreased in all 4 models of colitis. miR-21, which is increased in IBD, was increased in TNBS colitis but not the DSS colitis models. Further assessment of the miR-21-deficient 1-/- mice revealed that the deletion of miR-21 results in the exacerbation of both the TNBS and T cell-transfer models of colitis. Conclusions: miRNAs are differentially expressed in both human IBD and murine colitis, with overlap of several IBD-associated miRNAs. The demonstration that miR-21 deletion exacerbated CD4+ T cell-mediated models of colitis provides further evidence that miRNAs play significant roles in the pathogenesis of IBD. miRNAs expression was accesed for acute and chronic murine model of colitis induced by DSS or TNBS.Total of 20 samples with duplicates were analyed in this study.

Project description:Background: MicroRNAs (miRNAs) acting as negative regulators of gene expression are differentially expressed in intestinal tissues of patients with inflammatory bowel disease (IBD). Assessing the functional role of miRNAs in murine models of colitis facilitates elucidating the role of specific miRNAs in human IBD. The aim of this study was to determine the miRNA signature of murine models of colitis and to assess the influence of miR-21 on intestinal inflammation. Methods: miRNAs expression was accessed by microarray for acute and chronic murine model of colitis induced by DSS or TNBS. miR-21-deficient mouse and littermates controls were assessed in the standard DSS, TNBS and CD4+ T cell transfer models of colitis. RNAs of mouse colon and CD4+CD45RBHigh cells were analyzed by miRNA and mRNA microarray, and quantitative RT-PCR. Th1 polarization was accessed by flow-cytometry and ELISA. Results: Alterations of in miRNAs expression were identified for acute and chronic DSS colitis and TNBS colitis, receptively. The Expression of miRs-21, -142-3p and -223 was were distinct between DSS and TNBS models while overlap of numerous miRNAs was seen. Importantly, miRs-19b, -192 and -215, that are decreased in IBD, were significantly decreased in all 4 models of colitis. miR-21, which is increased in IBD, was increased in TNBS colitis but not the DSS colitis models. Further assessment of the miR-21-deficient 1-/- mice revealed that the deletion of miR-21 results in the exacerbation of both the TNBS and T cell-transfer models of colitis. Conclusions: miRNAs are differentially expressed in both human IBD and murine colitis, with overlap of several IBD-associated miRNAs. The demonstration that miR-21 deletion exacerbated CD4+ T cell-mediated models of colitis provides further evidence that miRNAs play significant roles in the pathogenesis of IBD. Gene expression profiles were established for normal miR-21-/- mice and wild type c57BL/6 mice (WT). Total of 6 samples with replicates were included in this study.

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).

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Gut Microbiota Metabolite Indole-3-Acetic Acid Maintains Intestinal Epithelial Homeostasis Through Mucin Sulfation

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