Inflammatory Bowel Disease Outcomes Following Fecal Microbiota Transplantation for Recurrent C. difficile Infection.

BACKGROUND: Recurrent Clostridioides difficile infection (CDI) in patients with inflammatory bowel disease (IBD) is a clinical challenge. Fecal microbiota transplantation (FMT) has emerged as a recurrent CDI therapy. Anecdotal concerns exist regarding worsening of IBD activity; however, prospective data among IBD patients are limited. METHODS: Secondary analysis from an open-label, prospective, multicenter cohort study among IBD patients with 2 or more CDI episodes was performed. Participants underwent a single FMT by colonoscopy (250 mL, healthy universal donor). Secondary IBD-related outcomes included rate of de novo IBD flares, worsening IBD, and IBD improvement-all based on Mayo or Harvey-Bradshaw index (HBI) scores. Stool samples were collected for microbiome and targeted metabolomic profiling. RESULTS: Fifty patients enrolled in the study, among which 15 had Crohn's disease (mean HBI, 5.8 ± 3.4) and 35 had ulcerative colitis (mean partial Mayo score, 4.2 ± 2.1). Overall, 49 patients received treatment. Among the Crohn's disease cohort, 73.3% (11 of 15) had IBD improvement, and 4 (26.6%) had no disease activity change. Among the ulcerative colitis cohort, 62% (22 of 34) had IBD improvement, 29.4% (11 of 34) had no change, and 4% (1 of 34) experienced a de novo flare. Alpha diversity significantly increased post-FMT, and ulcerative colitis patients became more similar to the donor than Crohn's disease patients (P = 0.04). CONCLUSION: This prospective trial assessing FMT in IBD-CDI patients suggests IBD outcomes are better than reported in retrospective studies.

Understanding the mechanisms of efficacy of fecal microbiota transplant in treating recurrent Clostridioides difficile infection and beyond: the contribution of gut microbial-derived metabolites.

Fecal microbiota transplant (FMT) is a highly-effective therapy for recurrent Clostridioides difficile infection (rCDI), and shows promise for certain non-CDI indications. However, at present, its mechanisms of efficacy have remained poorly understood. Recent studies by our laboratory have noted the particular key importance of restoration of gut microbe-metabolite interactions in the ability of FMT to treat rCDI, including the impact of FMT upon short chain fatty acid (SCFAs) and bile acid metabolism. This includes a significant impact of these metabolites upon the life cycle of C. difficile directly, along with potential postulated additional benefits, including effects upon host immune response. In this Addendum, we first present an overview of these recent advancements in this field, and then describe additional novel data from our laboratory on the impact of FMT for rCDI upon several gut microbial-derived metabolites which had not previously been implicated as being of relevance.

Effects of Fecal Microbiota Transplantation With Oral Capsules in Obese Patients.

BACKGROUND & AIMS: Studies in mice have shown that the intestinal microbiota can contribute to obesity via the anorexigenic gut hormone glucagon-like peptide 1 (GLP1) and bile acids, which affect lipid metabolism. We performed a randomized, placebo-controlled, pilot study of the effects of fecal microbiota transplantation (FMT) in obese, metabolically uncompromised patients. METHODS: We performed a double-blind study of 22 obese patients (body mass index [BMI] ≥5 kg/m2) without a diagnosis of diabetes, nonalcoholic steatohepatitis, or metabolic syndrome. Participants were assigned randomly (1:1) to groups that received FMT by capsules (induction dose of 30 capsules at week 4 and maintenance dose of 12 capsules at week 8) or placebo capsules. FMT capsules were derived from a single lean donor (BMI, 17.5 kg/m2). Patients were followed up through week 26; the primary outcome was safety. Stool and serum samples were collected from patients at baseline and at weeks 1, 4, 6, 8, and 12 after administration of the first dose of FMT or placebo and analyzed by 16S RNA gene sequencing. Stool and serum samples were analyzed for metabolomics by liquid chromatography-mass spectrometry. Additional outcomes were the change in area under the curve for GLP1 at week 12. RESULTS: We observed no significant differences in adverse events between patients who received FMT vs placebo. There was no increase in the area under the curve of GLP1 in either group. Patients who received FMT had sustained shifts in microbiomes associated with obesity toward those of the donor (P < .001). Patients who received FMT had a sustained decrease in stool levels of taurocholic acid (P < .05) compared with baseline; bile acid profiles began to resemble those of the donor more closely. We did not observe significant changes in mean BMI at week 12 in either group. CONCLUSIONS: In a placebo-controlled pilot study, we found that FMT capsules (derived from a lean donor) were safe but did not reduce BMI in obese metabolically uncompromised patients. The FMT capsules were well tolerated and led to sustained changes in the intestinal microbiome and bile acid profiles that were similar to those of the lean donor. ClinicalTrials.gov number: NCT02741518.

Microbial bile salt hydrolases mediate the efficacy of faecal microbiota transplant in the treatment of recurrent Clostridioides difficile infection.

OBJECTIVE: Faecal microbiota transplant (FMT) effectively treats recurrent Clostridioides difficile infection (rCDI), but its mechanisms of action remain poorly defined. Certain bile acids affect C. difficile germination or vegetative growth. We hypothesised that loss of gut microbiota-derived bile salt hydrolases (BSHs) predisposes to CDI by perturbing gut bile metabolism, and that BSH restitution is a key mediator of FMT's efficacy in treating the condition. DESIGN: Using stool collected from patients and donors pre-FMT/post-FMT for rCDI, we performed 16S rRNA gene sequencing, ultra performance liquid chromatography mass spectrometry (UPLC-MS) bile acid profiling, BSH activity measurement, and qPCR of bsh/baiCD genes involved in bile metabolism. Human data were validated in C. difficile batch cultures and a C57BL/6 mouse model of rCDI. RESULTS: From metataxonomics, pre-FMT stool demonstrated a reduced proportion of BSH-producing bacterial species compared with donors/post-FMT. Pre-FMT stool was enriched in taurocholic acid (TCA, a potent C. difficile germinant); TCA levels negatively correlated with key bacterial genera containing BSH-producing organisms. Post-FMT samples demonstrated recovered BSH activity and bsh/baiCD gene copy number compared with pretreatment (p<0.05). In batch cultures, supernatant from engineered bsh-expressing E. coli and naturally BSH-producing organisms (Bacteroides ovatus, Collinsella aerofaciens, Bacteroides vulgatus and Blautia obeum) reduced TCA-mediated C. difficile germination relative to culture supernatant of wild-type (BSH-negative) E. coli. C. difficile total viable counts were ~70% reduced in an rCDI mouse model after administration of E. coli expressing highly active BSH relative to mice administered BSH-negative E. coli (p<0.05). CONCLUSION: Restoration of gut BSH functionality contributes to the efficacy of FMT in treating rCDI.

Functional microbiomics: Evaluation of gut microbiota-bile acid metabolism interactions in health and disease.

There is an ever-increasing recognition that bile acids are not purely simple surfactant molecules that aid in lipid digestion, but are a family of molecules contributing to a diverse range of key systemic functions in the host. It is now also understood that the specific composition of the bile acid milieu within the host is related to the expression and activity of bacterially-derived enzymes within the gastrointestinal tract, as such creating a direct link between the physiology of the host and the gut microbiota. Coupled to the knowledge that perturbation of the structure and/or function of the gut microbiota may contribute to the pathogenesis of a range of diseases, there is a high level of interest in the potential for manipulation of the gut microbiota-host bile acid axis as a novel approach to therapeutics. Much of the growing understanding of the biology of this area reflects the recent development and refinement of a range of novel techniques; this study applies a number of those techniques to the analysis of human samples, aiming to illustrate their strengths, drawbacks and biological significance at all stages. Specifically, we used microbial profiling (using 16S rRNA gene sequencing), bile acid profiling (using liquid chromatography-mass spectrometry), bsh and baiCD qPCR, and a BSH enzyme activity assay to demonstrate differences in the gut microbiota and bile metabolism in stool samples from healthy and antibiotic-exposed individuals.