17 human-derived Clostridium strains (VE202), belonging to a bacterial cluster under-represented in active IBD, induce colonic IL-10-producing FOXP3+ regulatory T cells and prevent colitis in murine IBD models (Nature 2013). The VE202 consortium is a promising live biotherapeutic product for clinical application. However, its 1) therapeutic benefit on established colitis and 2) effect on intestinal microbiota composition remain unclear.