Improving ulcerative colitis prospects through fecal microbiota transfer: atypical donor microbiota can boost success rate.

Fecal microbiota transfer (FMT) has been used with variable success in the experimental treatment of ulcerative colitis (UC), and efforts to improve its efficacy very much remain a matter of trial and error. We recently predicted that atypical donor microbiota could improve results. Here, we provide experimental support for this prediction in a rat model where we induced a transition of the intestinal ecosystem to an alternative state characterized by chronic low-grade inflammation and dysbiosis. While autologous FMT did barely or not enhance the restoration of a healthy microbiota compared to a control group without FMT, the atypical allogenic microbiota from one of two donor rat strains proved remarkably successful in the restoration of a healthy microbiota, in some cases accompanied by a healthy distal colon histology. These results allow the rationalization of research efforts towards improvement of FMT efficacy in humans, and indicate that (initial) success of FMT should be monitored at the microbiota level as much as at the level of clinical symptoms. More importantly, they provide further support for our earlier published, clinical-data-based, conceptual model of the intestinal ecosystem which suggests promising opportunities for therapeutic innovation in UC treatment. This model notably predicts that, and explains why, symbio-therapy, acting on both microbiota and inflammation, may be more efficient than conventional inflammation-directed therapies, and can be used to guide and monitor treatments.