Project description:We performed a transcriptome analysis of Ruminococcus gnavus with and without 0.1% (w/w) agarooligosaccharide exposure to validate the mechanism of growth inhibition.
Project description:The gut microbiota and tumor-associated macrophages (TAM) impact anti-PD-1 checkpoint blockade. Reprogramming TAM by either blocking or deleting the macrophage receptor TREM2 attenuates tumor growth, and lack of functional TREM2 enhances tumor elimination by anti-PD-1. Here, we found that anti-PD-1 combined with TREM2 deficiency induces proinflammatory programs in intestinal macrophages and a concomitant expansion of Ruminococcus gnavus (R. gnavus) in the gut microbiota. Gavage of wild-type mice with R. gnavus recapitulated enhancement of anti-PD-1-mediated tumor elimination occurring in the absence of TREM2. The intestinal proinflammatory environment coincided with expansion, increased circulation and migration of TNF-producing CD4+ T cells to the tumor bed. Thus, TREM2 remotely controls anti-PD-1 checkpoint blockade through modulation of the intestinal immune environment and microbiota, with R. gnavus emerging as a potential probiotic agent for increasing responsiveness to anti-PD-1.
Project description:Mediterraneibacter gnavus, a core member of the human gut microbiota, secretes mediterrocin, a broad-spectrum bacteriocin. Identification and quantification of mediterrocin produced by Mediterraneibacter [Ruminococcus] gnavus strains RJX1121, RJX1123, and ATCC29149 using intact protein analysis.
Project description:Studying host-microbiota interactions is fundamental to understand mechanisms involved in intestinal inflammation and inflammatory bowel diseases. In this work, we studied these interactions in mice mono-associated with 4 bacteria and 2 yeasts, all representative of intestinal microbiota and/or associated with IBD pathogenesis: Bacteroides thetaiotaomicron, adhesive-invasive Escherichia coli (AIEC), Ruminococcus gnavus, Roseburia intestinalis, Saccharomyces boulardii and Candida albicans. Transcriptomics analyses showed that B. thetaiotaomicron had the highest immunological effect, being able to almost recapitulate the effects of a whole microbiota, and particularly induced Treg pathways. Furthermore, this analysis also pointed out the effects of E. coli AIEC LF82 on IDO activation and of S. boulardii on angiogenesis, as well as major effects of R. gnavus on metabolism. This work therefore reveals information on the role of each micro-organism and proposes several tracks to follow to better understand IBD pathogenesis and identify therapeutic targets 6 mono-associations + 2 controls (germ-free and conventionalized mice), with 5 to 7 mice per group.
Project description:Studying host-microbiota interactions is fundamental to understand mechanisms involved in intestinal inflammation and inflammatory bowel diseases. In this work, we studied these interactions in mice mono-associated with 4 bacteria and 2 yeasts, all representative of intestinal microbiota and/or associated with IBD pathogenesis: Bacteroides thetaiotaomicron, adhesive-invasive Escherichia coli (AIEC), Ruminococcus gnavus, Roseburia intestinalis, Saccharomyces boulardii and Candida albicans. Transcriptomics analyses showed that B. thetaiotaomicron had the highest immunological effect, being able to almost recapitulate the effects of a whole microbiota, and particularly induced Treg pathways. Furthermore, this analysis also pointed out the effects of E. coli AIEC LF82 on IDO activation and of S. boulardii on angiogenesis, as well as major effects of R. gnavus on metabolism. This work therefore reveals information on the role of each micro-organism and proposes several tracks to follow to better understand IBD pathogenesis and identify therapeutic targets
Project description:Paneth cells are the primary, and possibly the sole, source of lysozyme in the intestinal lumen. Mice lacking the Paneth cell lysozyme gene, Lyz1, had diminished NLR signaling and basal inflammation, and were further protected from experimental colitis. Protection depended on an enhanced goblet and tuft cell program that was driven by IL13-IL4Ra-Stat6 signaling and required an expansion of lysozyme-sensitive mucolytic bacteria. Forced ectopic lysozyme production in colonic epithelium suppressed these bacteria and exacerbated colitis. Single cell RNA-seq of Lyz1 KO lamina propria revealed an activated ILC2 profile towards cytokine production. One lysozymesensitive species, Ruminococcus gnavus , when processed by lysozyme, induced a pro-inflammatory response, while non-processed R. gnavus stimulated IL13 production in lymphocytes. Consistent with a role of lysozyme for cell-wall processing in the inflammatory response, Lyz1 KO microbiota was anti-colitogenic in lysozymedeficient hosts but colitogenic in lysozyme-sufficient hosts. Thus, Paneth cell lysozyme regulates inflammatory tone by modulating mucosal response to specific bacterial groups.