Defined microbiota transplant restores Th17/RORγt <sup>+</sup> regulatory T cell balance in mice colonized with inflammatory bowel disease microbiotas
Graham J. Britton, Eduardo J. Contijoch, Matthew P. Spindler, Varun Aggarwala, Belgin Dogan, Gerold Bongers, Lani San Mateo, Andrew Baltus, Anuk Das, Dirk Gevers, Thomas J. Borody, Nadeem O. Kaakoush, Michael A. Kamm, Hazel M. Mitchell, Sudarshan Paramsothy, José C. Clemente, Jean‐Frédéric Colombel, Kenneth W. Simpson, Marla C. Dubinsky, Ari Grinspan, Jeremiah J. Faith
Abstract
Significance Composition of gut microbiota is altered in many human diseases, including inflammatory bowel disease. Some hope that restoring microbiota to a healthy state could help treat such diseases. We have used mice colonized with microbiotas from humans with inflammatory bowel disease to study what happens when these mice receive a microbiota transplant from a set of healthy humans. We find that the mouse gut immune system is changed by microbiota transplants, becoming broadly less inflammatory and protecting mice from colitis. By culturing bacteria from these microbiotas, we identify one strain that induces inflammatory responses in mice and show that it is modified by microbiota transplant. We also show that increases in the density of microbiota following transplant may be antiinflammatory.