Project description:H3K27Ac enrichment in intestinal epithelial cells from intestine of germ-free and segmented filamentous bacteria (SFB)-monoassociated mice. Intestinal epithelial cells were harvested from the terminal ileum of germ-free or SFB mice. Chromatin immunoprecipitation was performed with anti-H3K27Ac. Sequencing was performed using the Illumina HiSeq2500. Reads were mapped to the mm10 genome using Bowtie.
Project description:Commensal bacteria influence host physiology, including immune responses, without invading host tissues. We show that proteins from segmented filamentous bacteria (SFB), which are immunomodulatory commensal microbes, are transferred into intestinal epithelial cells by adhesion-directed endocytosis that is distinct from the clathrin-dependent endocytosis of invasive pathogens. SFB transfer microbial cell wall-associated proteins, including an antigen that stimulates mucosal Th17 cell differentiation, into the cytosol of epithelial cells. Removal of CDC42 activity in vivo led to disruption of endocytosis induced by SFB, decreased epithelial antigen acquisition with consequent loss of immune modulation by SFB-specific CD4 T cells and mucosal Th17 cells. Our findings indicate direct communication between a resident gut microbe and the host and show that intestinal epithelial cells acquire antigens from commensal bacteria for generation of T-cell responses to the resident microbiota.
Project description:In this project we profiled small intestinal epithelium, lamina propria immune cells as well as intraepithelial immune cells from 5-weeks old WT mice derived from Jackson laboratories and littermate colonized with segmented filamentous bacteria (SFB) 2 weeks prior to analysis, using 10x droplet-based single-cell RNA sequencing.
Project description:Control of gut microbes is crucial for not only local defense in the intestine but also proper systemic immune responses. Although intestinal epithelial cells (IECs) play important roles in cytokine-mediated control of enterobacteria, the underlying mechanisms are not fully understood. Here we show that deletion of IkappaBzeta in IECs in mice leads to dysbiosis with marked expansion of segmented filamentous bacteria (SFB), thereby enhancing Th17 cell development and exacerbating autoimmune inflammatory diseases. Mechanistically, the IkappaBzeta deficiency results in Paneth cell loss and impaired expression of IL-17-inducible genes involved in IgA production. The Paneth cell loss is caused by aberrant activation of IFN-gamma signaling and a failure of IL-17-mediated recovery from IFN-gamma-induced damage. Thus, the IL-17R–IkappaBzeta axis in IECs contributes to the maintenance of intestinal homeostasis by serving as a key component in a regulatory loop consisting of the gut microbiota and immune cells
Project description:Microbiota-induced cytokine responses participate in gut homeostasis, but the cytokine balance at steady-state and the role of individual bacterial species in setting the balance remain elusive. Using gnotobiotic mouse models, we provide a systematic analysis of the role of microbiota in the induction of cytokine responses in the normal intestine. Colonization by a whole mouse microbiota orchestrated a broad spectrum of pro-inflammatory (Th1, Th17) and regulatory T cell responses. Unexpectedly, most tested complex microbiota and individual bacteria failed to efficiently stimulate intestinal cytokine responses. A potent cytokine-inducing function was however associated with non-culturable host-specific species, the prototype of which was the Clostridia-related Segmented Filamentous Bacterium, and this bacterial species recapitulated the coordinated maturation of T cell responses induced by the whole mouse microbiota. Our study demonstrates the non-redundant role of microbiota members in the regulation of gut immune homeostasis.
