Project description:We profiled transcriptome and accessible chromatin landscapes in intestinal epithelial cells (IECs) from mice reared in the presence or absence of microbiota. We show that regional differences in gene transcription along the intestinal tract were accompanied by major alterations in chromatin organization. Surprisingly, we discovered that microbiota modify host gene transcription in IECs without significantly impacting the accessible chromatin landscape. Instead, microbiota regulation of host gene transcription might be achieved by differential expression of specific TFs and enrichment of their binding sites in nucleosome depleted CRRs near target genes. Our results suggest that the chromatin landscape in IECs is pre-programmed by the host in a region-specific manner to permit responses to microbiota through binding of open CRRs by specific TFs. mRNA and accessible chromatin (DNase-seq) profiles from colonic and ileal IECs were compared between conventionally-raised (CR), germ-free (GF), and conventionalized (CV) C57BL/6 mice.
Project description:Remodeling of the gut microbiota is implicated in various metabolic and inflammatory diseases of the gastrointestinal tract. We hypothesized that the gut microbiota affects the DNA methylation profile of intestinal epithelial cells (IECs) which could, in turn, alter intestinal function. Here, we used mass spectrometry and methylated DNA capture to respectively investigate global and genome-wide DNA methylation of intestinal epithelial cells from germ-free (GF) and conventionally raised mice (CONV-R). In colonic IECs from GF mice, DNA was markedly hypermethylated. This was associated with a dramatic loss of Ten-Eleven-Translocation activity, a lower DNA methyltransferase activity and lower circulating levels of the one carbon metabolites cobalamin and folate. At the gene level, we found an enrichment for differentially methylated regions at proximity of genes regulating cytotoxicity of Natural Killer cells (FDR < 8.9E-6), notably members of the natural killer group 2 member D ligand superfamily Raet. Our results suggest that altered activity of methylation-modifying enzymes in GF mice influences the IEC epigenome at genes involved in the crosstalk between intestinal and immune cells. Epigenetic reprogramming of IECs by the gut microbiota may modulate intestinal function in diseases associated with altered gut microbiota.
Project description:We profiled transcriptome and accessible chromatin landscapes in intestinal epithelial cells (IECs) from mice reared in the presence or absence of microbiota. We show that regional differences in gene transcription along the intestinal tract were accompanied by major alterations in chromatin organization. Surprisingly, we discovered that microbiota modify host gene transcription in IECs without significantly impacting the accessible chromatin landscape. Instead, microbiota regulation of host gene transcription might be achieved by differential expression of specific TFs and enrichment of their binding sites in nucleosome depleted CRRs near target genes. Our results suggest that the chromatin landscape in IECs is pre-programmed by the host in a region-specific manner to permit responses to microbiota through binding of open CRRs by specific TFs.
Project description:Intestinal epithelial cells (IEC) express large amounts of major histocompatibility complex II (MHCII) molecules. Despite this long-appreciated observation, the function of epithelial MHCII-mediated signaling on gut homeostasis remains enigmatic. As IECs serve as the primary cellular barrier between intestinal microbes and underlying host immune cells, we reasoned that IEC-intrinsic antigen presentation may play a role in tolerogenic responses towards the microbiota. Mice with an IEC-intrinsic defect in MHCII expression (IECΔMHCII) develop elevated T cell-dependent IgA responses, but a reduction in microbiota responsive regulatory T cells (Tregs). Despite elevated IgA levels in IECΔMHCII mice, immunoglobulin repertoires exhibit less selection and IgA has reduced reactivity to the microbiota, which is associated with increased inter-individual variability in microbiota composition. Consistent with reductions in microbiota-responsive Tregs, IECΔMHCII mice develop worsened colitis. A striking difference observed in the absence of IEC-MHCII is that while transcription of MHCII is similar, underlying mononuclear phagocytes had reduced surface MHCII. Macrophages were found to be capable of acquiring MHCII molecules from IECs, and macrophages isolated from IECΔMHCII mice had decreased capacity to stimulate Treg development. Thus, epithelial-myeloid interactions govern development of adaptive responses to microbial antigens within the gastrointestinal tract.
Project description:Intestinal epithelial cells (IEC) express large amounts of major histocompatibility complex II (MHCII) molecules. Despite this long-appreciated observation, the function of epithelial MHCII-mediated signaling on gut homeostasis remains enigmatic. As IECs serve as the primary cellular barrier between intestinal microbes and underlying host immune cells, we reasoned that IEC-intrinsic antigen presentation may play a role in tolerogenic responses towards the microbiota. Mice with an IEC-intrinsic defect in MHCII expression (IECΔMHCII) develop elevated T cell-dependent IgA responses, but a reduction in microbiota responsive regulatory T cells (Tregs). Despite elevated IgA levels in IECΔMHCII mice, immunoglobulin repertoires exhibit less selection and IgA has reduced reactivity to the microbiota, which is associated with increased inter-individual variability in microbiota composition. Consistent with reductions in microbiota-responsive Tregs, IECΔMHCII mice develop worsened colitis. A striking difference observed in the absence of IEC-MHCII is that while transcription of MHCII is similar, underlying mononuclear phagocytes had reduced surface MHCII. Macrophages were found to be capable of acquiring MHCII molecules from IECs, and macrophages isolated from IECΔMHCII mice had decreased capacity to stimulate Treg development. Thus, epithelial-myeloid interactions govern development of adaptive responses to microbial antigens within the gastrointestinal tract.
Project description:Intestinal epithelial cells (IEC) express large amounts of major histocompatibility complex II (MHCII) molecules. Despite this long-appreciated observation, the function of epithelial MHCII-mediated signaling on gut homeostasis remains enigmatic. As IECs serve as the primary cellular barrier between intestinal microbes and underlying host immune cells, we reasoned that IEC-intrinsic antigen presentation may play a role in tolerogenic responses towards the microbiota. Mice with an IEC-intrinsic defect in MHCII expression (IECΔMHCII) develop elevated T cell-dependent IgA responses, but a reduction in microbiota responsive regulatory T cells (Tregs). Despite elevated IgA levels in IECΔMHCII mice, immunoglobulin repertoires exhibit less selection and IgA has reduced reactivity to the microbiota, which is associated with increased inter-individual variability in microbiota composition. Consistent with reductions in microbiota-responsive Tregs, IECΔMHCII mice develop worsened colitis. A striking difference observed in the absence of IEC-MHCII is that while transcription of MHCII is similar, underlying mononuclear phagocytes had reduced surface MHCII. Macrophages were found to be capable of acquiring MHCII molecules from IECs, and macrophages isolated from IECΔMHCII mice had decreased capacity to stimulate Treg development. Thus, epithelial-myeloid interactions govern development of adaptive responses to microbial antigens within the gastrointestinal tract.