Project description:Mucus accumulation is a key feature of respiratory diseases such as cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). This is associated with goblet cell metaplasia and mucin overexpression, which can be induced by the increased activity of neutrophil elastase. The aim of the study was to characterization of mucus and epithelial cell proteomics in a porcine pancreatic elastase (PPE) mouse model of COPD/CF. The major proteins detected in mucus plugs obtained from PPE-treated mice included mucins Muc5ac and Muc5b, mucus-related proteins Clca1, Fcgbp, and Bpifb1. These proteins were upregulated in bronchoalveolar lavage (BAL) fluid and epithelial cells in mice exposed to elastase. Similar changes were found in BAL fluid of COPD patients.
Project description:Mucus/MUC2 from TGM3-deficient mice is less cross-linked with isopeptide-bond cross-links compared to Mucus/MUC2 from WT mice. This results in protease-labile MUC2-molecules that become degraded in the colonic lumen
Project description:The inter-organ cross talk between liver and intestine has been focus of intense research. Key in this cross-talk are bile acids, which are secreted from the liver into the intestine and, via the enterohepatic circulation, reach back to the liver. Important new insights have been gained in the Farnesoid X receptor (Fxr)-mediated communication from intestine-to-liver in health and disease. However, liver-to-intestine communication and the role of bile acids and FXR in this cross talk remain elusive. Here, we analyse Fxr-mediated liver-to-gut communication, and its consequences in the colon. Mice in which Fxr was selectively ablated in intestine (Fxr-intKO), the liver (Fxr-livKO), or in the full body (Fxr-totKO) were engineered. The effects on colonic gene expression (RNA sequencing), on the microbiome (16S rRNA Gene Sequencing) and on mucus barrier were analyzed. Compared to Fxr-intKO and Fxr-totKO mice, more genes were differentially expressed in the colons of Fxr-livKO mice relative to control mice (731, 1824 and 3272 respectively), suggestive of a strong role of hepatic Fxr in liver-to-gut communication. The colons of Fxr-livKO showed increased expression of anti-microbial genes, such as Regenerating islet-derived 3 beta and gamma (Reg3β and Reg3γ), Toll-like receptors (Tlrs), inflammasome related genes and differential expression of genes belonging to the ‘Mucin-type O-glycan biosynthesis’ pathway. Compared to control mice, Fxr-livKO mice have decreased levels of the predicted mucin degrading bacterium Turicibacter and a concomitant increase in the thickness of the inner sterile mucus layer. In conclusion, ablation of Fxr in the liver has a major effect on colonic gene expression, the gut microbiome and on the permeability of the mucus layer. This stresses the importance of the Fxr-mediated liver-to-gut signaling.
Project description:Antibiotic use is a risk factor for development of inflammatory bowel diseases (IBDs). IBDs are characterized by a damaged mucus layer, which does not properly separate the host intestinal epithelium from the microbiota. Here, we hypothesized that antibiotics might affect the integrity of the mucus barrier. By systematically determining the effects of different antibiotics on mucus layer penetrability we found that oral antibiotic treatment led to breakdown of the mucus barrier and penetration of bacteria into the mucus layer. Using fecal microbiota transplant, RNA sequencing followed by machine learning and ex vivo mucus secretion measurements, we determined that antibiotic treatment induces ER stress and inhibits colonic mucus secretion in a microbiota-independent manner. This mucus secretion flaw led to penetration of bacteria into the colonic mucus layer, translocation of microbial antigens into circulation and exacerbation of ulcerations in a mouse model of IBD. Thus, antibiotic use might predispose to development of intestinal inflammation by impeding mucus production.
Project description:The colonic inner mucus layer protects us from pathogen invasion and commensal-induced inflammation. Mucus abnormalities are common in ulcerative colitis (UC), but their cause and importance are unknown. The aim of this study was to determine the role of compositional mucus barrier alterations in UC. In this single-center case-control study, sigmoid colon biopsies were obtained from UC patients with ongoing inflammation (n=36) and in remission (n=28), and from 47 patients without inflammatory bowel disease. Mucus samples were collected from biopsies ex vivo, and their protein composition analyzed by mass spectrometry. Mucus barrier integrity and goblet cell response to microbial challenge were also assessed for a subset of patients. The core colonic mucus proteome was shown to consist of a small set of 29 secreted proteins. Patients with active UC had reduced levels of major structural components, including the mucin MUC2 (p<0.0001), also in mucus from non-inflamed segments, and their goblet cell secretory response to microbial stimulus was abrogated. Functional mucus barrier failure was observed in a subset of UC patients with and without active inflammation, and accompanied by alterations in proteins associated with mucus secretion and luminal organization. This study represents the first characterization and comparison of the mucus proteomes of the inflamed and non-inflamed colon. Core mucus structural components were reduced in active UC, also in mucus from non-inflamed segments. Thus, weakening of the mucus barrier is likely to occur early in UC pathogenesis, and represents a novel target for intervention.
Project description:Estrogen receptor β (ERβ) and NOD-, LRR- and pyrin domain-containing 6 (NLRP6) are highly expressed in intestinal tissues and reduce intestinal inflammation, but their underlying mechanisms are unclear. We found that ERβ and NLRP6 levels were reduced in patients with inflammatory bowel disease (IBD), and that deletion of ERβ or NLRP6 was exacerbated colitis in mouse models. We discovered that ERβ exerted its anti-inflammatory activity by inducing NLRP6-mediated autophagy. Specifically, ERβ directly regulated NLRP6 gene expression and NLRP6 inflammasome activation through genomic and non-genomic effects. NLRP6 directly interacted with multiple autophagy-related proteins (including ULK1, BECN1, ATG5-ATG12-ATG16L1 complex, p62, and PHB2). Autophagy stimulation suppresses the inflammatory response by eliminating excess ERβ, NLRP6, ASC, Casp-1, IL-1β, TNF-α and damaged mitochondria. These findings indicate that ERβ-NLRP6-autophagy forms a negative feedback loop to maintain intestinal epithelial cell homeostasis and facilitate tissue repair.