Project description:Loss of immune tolerance to the gut microbiome plays a pathogenic role in inflammatory bowel disease (IBD). How dietary factors alter host immune-gut microbiome interactions in IBD is unclear. Here, we apply multi-omics (IgA-SEQ, IgG-SEQ, blood scRNA-seq and immune repertoire sequencing) to investigate the effects of 12 weeks of vitamin D on host immune microbe interactions in patients with IBD. Vitamin D treatment associates with decreased disease activity and inflammatory markers and increased IgA-bound and decreased IgG-bound gut microbiota. Vitamin D alters the profiles of IgA-bound (increased Lachnospiraceae, Blautia) and IgG-bound (decreased Proteobacteria, Enterococcaceae) gut bacteria. Vitamin D increases BAFF signaling between plasmacytoid dendritic cells and B cells, alters BCR and TCR clonotypes that associate with Ig-bound gut microbiota, and increases α4β7+ B and T regulatory cells. Our results demonstrate that vitamin D promotes immune tolerance to gut microbiota in patients with IBD. Clinical trial is registered under NCT04828031
Project description:Loss of immune tolerance to the gut microbiome plays a pathogenic role in inflammatory bowel disease (IBD). How dietary factors alter host immune-gut microbiome interactions in IBD is unclear. Here, we apply multi-omics (IgA-SEQ, IgG-SEQ, blood scRNA-seq and immune repertoire sequencing) to investigate the effects of 12 weeks of vitamin D on host immune microbe interactions in patients with IBD. Vitamin D treatment associates with decreased disease activity and inflammatory markers and increased IgA-bound and decreased IgG-bound gut microbiota. Vitamin D alters the profiles of IgA-bound (increased Lachnospiraceae, Blautia) and IgG-bound (decreased Proteobacteria, Enterococcaceae) gut bacteria. Vitamin D increases BAFF signaling between plasmacytoid dendritic cells and B cells, alters BCR and TCR clonotypes that associate with Ig-bound gut microbiota, and increases α4β7+ B and T regulatory cells. Our results demonstrate that vitamin D promotes immune tolerance to gut microbiota in patients with IBD. Clinical trial is registered under NCT04828031
Project description:Loss of immune tolerance to the gut microbiome plays a pathogenic role in inflammatory bowel disease (IBD). How dietary factors alter host immune-gut microbiome interactions in IBD is unclear. Here, we apply multi-omics (IgA-SEQ, IgG-SEQ, blood scRNA-seq and immune repertoire sequencing) to investigate the effects of 12 weeks of vitamin D on host immune microbe interactions in patients with IBD. Vitamin D treatment associates with decreased disease activity and inflammatory markers and increased IgA-bound and decreased IgG-bound gut microbiota. Vitamin D alters the profiles of IgA-bound (increased Lachnospiraceae, Blautia) and IgG-bound (decreased Proteobacteria, Enterococcaceae) gut bacteria. Vitamin D increases BAFF signaling between plasmacytoid dendritic cells and B cells, alters BCR and TCR clonotypes that associate with Ig-bound gut microbiota, and increases α4β7+ B and T regulatory cells. Our results demonstrate that vitamin D promotes immune tolerance to gut microbiota in patients with IBD. Clinical trial is registered under NCT04828031
Project description:B cell receptor repertoire is with huge diversity among mouse individuals that hamper the search for true signals caused by targeted experimental factors. The data was sequenced for the measurement of the spectrum similarity among baseline mice. It aimed to compare and assess the convergence of the repertoire in two mouse strains (BALB/c, n=8 and C57BL/6J, n=5) and two kinds of sample type (PBMC form blood and splenocyte form spleen). Among them, each sample from 3 BALB/c mice were divided into two and sequenced respectively. 5' RACE method and a set of mixed specific primers for IgA/G/M isotypes were applied to amplify the targeted region of IgH.
Project description:Early life exposure to antibiotics alters the gut microbiome. These alterations lead to changes in metabolic homeostasis and an increase in host adiposity. We used microarrays to identify metabolic genes that may be up- or down-regulated secondary to antibiotic exposure. Low dose antibiotics have been widely used as growth promoters in the agricultural industry since the 1950’s, yet the mechanisms for this effect are unclear. Because antimicrobial agents of different classes and varying activity are effective across several vertebrate species, we hypothesized that such subtherapeutic administration alters the population structure of the gut microbiome as well as its metabolic capabilities. We generated a model of adiposity by giving subtherapeutic antibiotic therapy (STAT) to young mice and evaluated changes in the composition and capabilities of the gut microbiome. STAT administration increased adiposity in young mice and altered hormones related to metabolism. We observed substantial taxonomic changes in the microbiome, changes in copies of key genes involved in the metabolism of carbohydrates to short-chain fatty acids (SCFA), increases in colonic SCFA levels, and alterations in the regulation of hepatic metabolism of lipids and cholesterol. In this model, we demonstrate the alteration of early life murine metabolic homeostasis through antibiotic manipulation. C57BL6 mice were divided into low-dose penicillin or control groups. Given antibiotics via drinking water after weaning. Sacrificed and liver sections collected for RNA extraction.
Project description:Broad-spectrum antibiotics are frequently prescribed to children. The period of early-childhood represents a time where the developing microbiota may be more sensitive to environmental perturbations, which thus might have long-lasting host consequences. We hypothesized that even a single early-life broad-spectrum antibiotic course at a therapeutic dose (PAT) leads to durable alterations in both the gut microbiota and host immunity. In C57BL/6 mice, a single early-life tylosin (macrolide) course markedly altered the intestinal microbiome, and affected specific intestinal T-cell populations and secretory IgA expression, but PAT-exposed adult dams had minimal immunologic alterations. No immunological effects were detected in PAT-exposed germ-free animals; indicating that microbiota are required for the observed activities. Transfer of PAT-perturbed microbiota led to delayed sIgA expression indicating that the altered microbiota is sufficient to transfer PAT-induced effects. PAT exposure had lasting and transferable effects on microbial community network structure. Together these results indicate the impact of a single therapeutic early-life antibiotic course altering the microbiota and modulating host immune phenotypes that persist long after exposure has ceased.
Project description:Gut-educated IgA-secreting plasma cells that disseminate beyond the mucosa and into systemic tissues can help prevent disease in several contexts. Here we show, the commensal bacteria Bacteroides fragilis (Bf), is an efficient inducer of systemic IgA responses. The generation of bone marrow IgA plasma cells and high levels of serum IgA specific to Bf requires robust intestinal colonization. Bf-specific IgA responses were severely diminished in mice lacking Peyer’s patches, but not mice lacking a cecal patch. Colonization resulted in few changes in the host transcriptional profile in the gut, suggesting a commensal relationship. High levels of Bf-specific serum IgA, but not IgG, provided protection from peritoneal abscess formation in a bowel perforation model of Bf dissemination. These findings demonstrate a critical role for bacterial colonization and Peyer’s patches in the induction of robust systemic IgA responses that confer protection from bacterial dissemination originating from the gut.
Project description:Immunoglobulin A (IgA) most predominant antibody isotype at mucosal surfaces and is regulated by both T cell-dependent (TD) and independent (TI) mechanisms. In the TD pathway, T follicular helper (TFH) cells provide help to B cells to generate high-affinity antibodies. T follicular regulatory (TFR) cells fine-tune antibody responses, but precisely how these cellsregulate microbiota-directed IgA at mucosal sites has been unclear. Here, we used a TFR-deficient mouse model (Foxp3Cre Bcl6fl/fl; Bcl6FC) in which the gut microbiota develops in the absence of TFR cells, while the broader regulatory T cell compartment remains intact. While Bcl6FC mice showed similar levels of IgA-coated commensal bacteria to wild-type mice in the naïve state, following oral immunization, Bcl6FC mice exhibited a durable increase in IgA-coated commensal bacteria in feces and small intestine, without changes in overall community composition or epithelial barrier permeability. IgA-seq analysis of Bcl6FC mice revealed an increased diversity of IgA-coated taxa, both in naïve and orally immunized mice. IgA coating index analysis, a measure of IgA affinity, identified higher IgA binding to multiple taxa in Bcl6C mice compared to control mice. Consistent with these findings, sera from immunized Bcl6FC mice showed increased IgA binding to Alloprevotella and Klebsiella species but not to E. coli or Group A/B Streptococcus compared to control mice. B cell receptor repertoire sequencing demonstrated divergent patterns of somatic hypermutation (SMH) for IgA and IgG, where TFR cells repressed IgA SMH but enhanced IgG somatic hypermutation. Mechanistically, suppression of commensal-directed IgA required TFR-derived IL-10 but was independent of CTLA-4. IL-10 directly inhibited TGF-β-driven IgA class switching of B cells in vitro. Together, our data identify TFR cells as critical gatekeepers of mucosal IgA responses, constraining commensal-specific IgA responses through a novel IL-10-dependent pathway. Our findings haveimportant implications for regulation of the microbiome by TFR cells and IgA.