Page 19 - Introduction to FMT

FMT Introduction

Surprisingly, obesogenic properties of the gut microbiome can be transmitted through FMT as well. A
case report documented the transmission of an obese phenotype from an overweight donor to a lean
patient following FMT for CDI treatment [49]. The donor was a young, obese relative undergoing rapid
weight gain at the time of donation. The recipient was an individual who had never been obese. After
receiving FMT, the recipient had rapid unintentional weight gain that could not be explained by recovery
from CDI alone. Interestingly, the recipient reported increased appetite. These observations remain
controversial given that it is a case report. However, it is consistent with rodent studies where transfer of
fecal matter from obese mice to germ-free mice transmits the metabolic phenotype [35]. Regardless, the
results of this report have affected FMT protocol at many institutions that now exclude obese donors
from donating.

Conclusion

FMT remains an exciting therapy with abundant potential. Nevertheless, there has been a lack of
controlled, randomized trials for metabolic disease. Initially, the FDA considered FMT an IND, making it
difficult for practitioners to use until all other therapeutic options had been exhausted. However, in 2014
the FDA stated that it would exercise enforcement discretion, allowing physicians to use FMT without IND
applications for the treatment of CDI. For more investigational indications of FMT, an IND application with
the FDA is still required.

Given the amount of controlled clinical studies currently testing FMT for metabolic syndrome we should
have a clear indication in the next few years of whether or not microbiota changes are causative or
correlative in this rising epidemic, and whether altering the gut microbiome through FMT or similar
procedures will provide new therapeutic options for obesity and its associated metabolic disorders.

Abbreviations

FMT Fecal microbiota transplant

SCFA short chain fatty acid

BA bile acid

CDI Clostridium difficile infection

IBD Inflammatory bowel disease

IND investigational new drug

T2D type 2 diabetes

FMT Introduction