Fecal microbiota transplantation for metabolic syndrome and obesity: a sytematic review and meta-analysis based on randomized clinical trials

Background: Fecal microbiota transfer (FMT) is a therapeutic option consisting of the infusion of donor fecal material into the intestine of patients.FMT might be beneficial for several diseases associated with a disturbed gut microbiota, such as chronic gastrointestinal inflammatory diseases.One of those is microscopic colitis (MC) comprised of the subtypes collagenous colitis (CC) and lymphocytic colitis (LC).Typical MC symptoms are chronic watery diarrhea, abdominal pain and weight loss which significantly impact quality of life.Aim: In this proof-of-concept study, the effect of repeated FMT on collagenous colitis was assessed.Method: Ten CC patients received repeated FMTs and were followed for six months.The first FMT was administered via colonoscopy into the caecum of a cleansed bowel, the second and third FMT were administered via enemas into the rectum two and four weeks after the first FMT.Local and systemic immune response were assessed before and after FMT (flow cytometric analysis of colonic lymphocytes isolated from biopsies from the descending colon and clinical blood analysis).Additionally, symptoms and general health were assessed by questionnaires at various time points throughout the study.Results: Seven patients were in remission (<3 total stools per day of which <1 watery stool, assessed by daily diary) six weeks after the first FMT (corresponding to two weeks after the last FMT).An eighth patient achieved remission following FMT at a later time point.However, only three of those patients had a clinically active disease at baseline defined by number of stools.Two additional patients did not achieve remission at any time point.Overall, when analyzing data from all patients, repeated FMT did not result in a statistically significant reduction of number or improvement of consistency of stools (watery, non-watery and total stools) at any time point.Several gastrointestinal symptoms (assessed by gastrointestinal symptom rating scale, GSRS) were significantly improved by FMT.Namely, abdominal pain was significantly reduced six weeks after the first FMT (GSRS subscore decreased by 1.1, p<0.05).Others, such as diarrhea was reduced four and eight weeks after the first FMT and indigestion was reduced eight and twelve weeks after the first FMT.Similarly, patients reported less disease-related worries (assessed by short health scale).Furthermore, the quality of life improved during the course of the study.No substantial systemic effects or effects on the local immune system of FMT were observed.No serious adverse events due to FMT were reported.Conclusion: FMT is able to improve symptoms in a yet undefined subset of CC patients.Further analysis could help to characterize this subset and to understand if these results can be generalized to all MC patients including LC patients.