Project description:Gut dysbiosis is closely involved in the pathogenesis of inflammatory bowel disease (IBD). However, it remains unclear whether IBD-associated gut dysbiosis plays a primary role in disease manifestation or is merely secondary to intestinal inflammation. Here, we established a humanized gnotobiotic (hGB) mouse system to assess the functional role of gut dysbiosis associated with two types of IBD - Crohn's disease (CD) and ulcerative colitis (UC). In order to explore the functional impact of dysbiotic microbiota in IBD patients on host immune responses, we analyzed gene expression profiles in colonic mucosa of hGB mice colonized with healty (HC), CD, and UC microbiota.
Project description:Hepcidin is demonstrated to be the key iron regulatory hormone, produced by the liver. Here we show an unexpected role of hepcidin as a master initiator of the local and systemic inflammatory response. We found that hepcidin was highly expressed in the colon of two major idiopathic inflammatory bowel diseases : Crohn's disease (CD) and ulcerative colitis (UC). Thanks to the generation of intestinal specific hepcidin KO mice (Hepc{delta}int), we found in a DSS-induced colitis model that hepcidin mediated the induction of key inflammatory cytokines and was protective against intestinal injury. In a model of LPS-induced acute inflammation, intestinal hepcidin expression was increased through a TLR4 dependent pathway andwas required for intestinal neutrophil infiltration and inflammation. Strikingly, intestinal hepcidin was absolutely required for the systemic production of key inflammatory cytokines (IL-6, CXCL1, TNF-alpha ...) as well as for the setting of the hypoferremia of inflammation. In a sepsis model, Hepc{delta}int mice were protected against LPS-induced mortality. Mechanistically, we showed that hepcidin was a direct neutrophil chemoattractant and a proinflammatory molecule in macrophages through a Myd88 dependent pathway. Altogether, we demonstrated that Hepcidin is a key new essential component of the immune system and may be a promising target in many inflammatory diseases. We used microarrays to detail the global program of gene expression of BMDM treat with hepcidin for 1 hour.
Project description:Endurance exercise has a dramatic impact on the functionality of mitochondria and on the composition of intestinal microbiome, but the mechanisms regulating the crosstalk between these two components are still largely unknown. Here, we sampled 20 elite horses before and after an endurance race and used blood transcriptome, blood metabolome and fecal microbiome to describe the microbiota-mitochondria inter-talk. A subset of mitochondria-related differentially expressed genes involved in pathways such as energy metabolism, oxidative stress and inflammation was discovered and then shown to be associated with butyrate-producing bacteria of the Lachnospiraceae family, especially Eubacterium. The mechanisms involved were not fully understood, but through the action of their metabolites likely acted on PPARδ, the FRX-CREB axis and their downstream targets to delay the onset of hypoglycemia, inflammation and extend running time. Our results also suggested that circulating free fatty acids may act not merely as fuel but drive mitochondrial inflammatory responses triggered by the translocation of gut bacterial polysaccharides following endurance. Targeting the gut-mitochondria axis appears therefore as a potential strategy to enhance athletic performance.
Project description:The early life microbiome plays important roles in host immunological and metabolic development. Because type 1 diabetes (T1D) incidence has been increasing substantially in recent decades, we hypothesized that early-life antibiotic use alters gut microbiota that predisposes to disease. Using NOD mice that are genetically susceptible to T1D, we examined the effects of exposure to either continuous low-dose antibiotics or pulsed therapeutic antibiotics (PAT) early in life, mimicking childhood exposures. We found that in mice receiving PAT, T1D incidence was significantly higher, microbial community composition and structure differed compared with controls. In pre-diabetic male PAT mice, the intestinal lamina propria had lower Th17 and T reg proportions and intestinal SAA expression than in controls, suggesting key roles in transducing the altered microbiota signals. PAT affected microbial lipid metabolism and host cholesterol biosynthetic gene expression. These findings show that early-life antibiotic treatments alter the gut microbiota and its metabolic capacities, intestinal gene expression, and T-cell populations, accelerating T1D onset in NOD mice.
Project description:Susceptibility to Crohn's disease, a complex inflammatory disease involving the small intestine, is controlled by over 30 loci. One Crohn's disease risk allele is in ATG16L1, a gene homologous to the essential yeast autophagy gene ATG16 (ref. 2). It is not known how ATG16L1 or autophagy contributes to intestinal biology or Crohn's disease pathogenesis. To address these questions, we generated and characterized mice that are hypomorphic for ATG16L1 protein expression, and validated conclusions on the basis of studies in these mice by analysing intestinal tissues that we collected from Crohn's disease patients carrying the Crohn's disease risk allele of ATG16L1. Here we show that ATG16L1 is a bona fide autophagy protein. Within the ileal epithelium, both ATG16L1 and a second essential autophagy protein ATG5 are selectively important for the biology of the Paneth cell, a specialized epithelial cell that functions in part by secretion of granule contents containing antimicrobial peptides and other proteins that alter the intestinal environment. ATG16L1- and ATG5-deficient Paneth cells exhibited notable abnormalities in the granule exocytosis pathway. In addition, transcriptional analysis revealed an unexpected gain of function specific to ATG16L1-deficient Paneth cells including increased expression of genes involved in peroxisome proliferator-activated receptor (PPAR) signalling and lipid metabolism, of acute phase reactants and of two adipocytokines, leptin and adiponectin, known to directly influence intestinal injury responses. Importantly, Crohn's disease patients homozygous for the ATG16L1 Crohn's disease risk allele displayed Paneth cell granule abnormalities similar to those observed in autophagy-protein-deficient mice and expressed increased levels of leptin protein. Thus, ATG16L1, and probably the process of autophagy, have a role within the intestinal epithelium of mice and Crohn's disease patients by selective effects on the cell biology and specialized regulatory properties of Paneth cells. Experiment Overall Design: 4 Samples: 2 replicates of Atg16-hypomorph Paneth cells and 2 replicates of Wildtype Paneth cells.
Project description:A focussed microarray chip was constructed specifically for studying basal colonic gene expression in patients with Spondyloarthropathy (SpA) and Crohn's disease (CD) (ref: PMID 16476712). These focus microarrays were used 1) to study common changes in gene expression between SpA and CD, providing early markers in the follow-up study of patients with SpA and particularly these patients that evolve into clinically overt CD; and 2) to identify new candidate genes for CD by integrating gene expression data with genetic information. Keywords: Crohn's Disease, Spondylarthropathy, biopsies This experiment was done in a dye-swap design in which all samples of interest were compared to a pooled sample.
Project description:We analyzed the effects of antibiotics using a popular model of gut microbiota depletion in mice by a cocktail of antibiotics. We combined intestinal transcriptome together with metagenomic analysis of the gut microbiota to develop a new bioinformatics approach that probes the links between microbial components and host functions. We found that most antibiotic-induced alterations can be explained by three factors: depletion of the microbiota; direct effects of antibiotics on host tissues; and the effects of remaining antibiotic-resistant microbes. While microbe depletion led to down-regulation of immunity, the two other factors primarily inhibited mitochondrial gene expression and amounts of active mitochondria, and induced cell death. By reconstructing and analyzing a transkingdom network, we discovered that these toxic effects were mediated by virulence/quorum sensing in antibiotic-resistant bacteria. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
Project description:Hepcidin is demonstrated to be the key iron regulatory hormone, produced by the liver. Here we show an unexpected role of hepcidin as a master initiator of the local and systemic inflammatory response. We found that hepcidin was highly expressed in the colon of two major idiopathic inflammatory bowel diseases : Crohn's disease (CD) and ulcerative colitis (UC). Thanks to the generation of intestinal specific hepcidin KO mice (Hepc{delta}int), we found in a DSS-induced colitis model that hepcidin mediated the induction of key inflammatory cytokines and was protective against intestinal injury. In a model of LPS-induced acute inflammation, intestinal hepcidin expression was increased through a TLR4 dependent pathway andwas required for intestinal neutrophil infiltration and inflammation. Strikingly, intestinal hepcidin was absolutely required for the systemic production of key inflammatory cytokines (IL-6, CXCL1, TNF-alpha ...) as well as for the setting of the hypoferremia of inflammation. In a sepsis model, Hepc{delta}int mice were protected against LPS-induced mortality. Mechanistically, we showed that hepcidin was a direct neutrophil chemoattractant and a proinflammatory molecule in macrophages through a Myd88 dependent pathway. Altogether, we demonstrated that Hepcidin is a key new essential component of the immune system and may be a promising target in many inflammatory diseases.
Project description:A focussed microarray chip was constructed specifically for studying basal colonic gene expression in patients with Spondyloarthropathy (SpA) and Crohn's disease (CD) (ref: PMID 16476712). These focus microarrays were used 1) to study common changes in gene expression between SpA and CD, providing early markers in the follow-up study of patients with SpA and particularly these patients that evolve into clinically overt CD; and 2) to identify new candidate genes for CD by integrating gene expression data with genetic information. Keywords: Crohn's Disease, Spondylarthropathy, biopsies
Project description:Disruption of gut barrier function and intestinal immune cell homeostasis are increasingly considered critical players in pathogenesis of extra-intestinal inflammatory diseases, including multiple sclerosis (MS) and its prototypical animal model, theexperimental autoimmune encephalomyelitis (EAE). Breakdown of epithelial barriers increases intestinal permeability and systemic dissemination of microbiota-derived molecules. However,whetherthe gut-vascular barrier (GVB) is altered during EAE has not been reported. Here, we demonstrate that endothelial cell proliferation and vessel permeability increase before EAE clinical onset, leadingto vascular remodelingand expansion of intestinal villi capillary bed during disease symptomatic phasein an antigen-independent manner. Concomitant to onset of angiogenesis observed prior to neurological symptoms, we identify an increase of intestinal perivascular immune cells characterized by the surface markerlymphatic vessel endothelial hyaluronic acid receptor 1 (LYVE-1). LYVE-1+is expressed more frequently on B cells that show high levels of CD73 and have proangiogenic properties. B cell depletion was sufficient tomitigate enteric blood endothelial cell proliferation following immunization for EAE. In conclusion, we propose that altered intestinal vasculature driven by a specialized LYVE-1+B cell subset promotes angiogenesis and that loss of GVB function is implicated in EAE development and autoimmunity.