Mechanisms of Fecal Microbiota Transplant Protection from Recurrent C. difficile

Project Summary Introduction: Recurrent C. difficile infection (rCDI) occurs in one of every five patients infected. The most effective therapy is fecal microbiota transplant (FMT). Here we propose to understand how FMT acts to protect patients with rCDI through colon biopsies pre- and post-FMT, and through mouse models of FMT. Hypothesis: FMT prevents recurrent CDI (rCDI) by: (1) decreasing SNS signaling via α2AR; (2) activating ILC2; and (3) mediating intestinal epithelial proliferation and repair via EGFR. Significance: Successful completion of the work will identify mechanisms of action of FMT, which is the most effective therapy for rCDI, and will lay the foundation for therapy for rCDI targeting the SNS, immune system and/or EGFR as an adjunct and/or replacement for FMT. In addition the work has potential applications in other diseases where FMT is being applied including inflammatory bowel disease and cancer checkpoint inhibitor resistance. Investigators: The MPIs William Petri and Girija Ramakrishnan have collaborated and co-published for over 25 years and together have set the stage for the proposed studies through a clinical study of humans undergoing FMT for rCDI, and through mechanisms of action studies of CDI and FMT in mouse models. Innovation: The hypothesis is innovative as it challenges, by its exploration of FMT impact on the host, the existing paradigm that FMT acts predominantly by its impact on the pathogen C. difficile. Innovative approaches include the longitudinal study of subjects undergoing FMT for rCDI, transgenic mouse models to probe the actions of the SNS, ILC and EGFR in rCDI and FMT, and innovative techniques including spatial transcriptomics and scRNAseq of the colon. Progress over the last 5 years of funding: Includes the discoveries that the TNFα and IL-8 response to CDI in the mouse model is initiated by a2AR activation; that IL-33 acts via ILC2 in mice to block Th17 and promote anti-TcdB antibody production; and that in humans FMT increased amphiregulin, crypt depth and Myc and mTOR signaling. There have been 15 peer-reviewed original research papers, 3 preprints, and 3 reviews over the 5-year funding period supported by 5R01AI152477 and two patent filings. Approach: In each Aim a mouse model of FMT will be compared to humans undergoing FMT. Specific Aim 1: Test if FMT prevents CDI damage by downregulating the SNS. Specific Aim 2: Test if FMT decreases inflammation by activating ILC2 Specific Aim 3: Test if FMT repairs the gut via EGFR Environment: The University of Virginia Division of Infectious Diseases and Beirne Carter Immunology Center provide a rich intellectual environment in the Carter-Harrison Medical Research Building where the work will be conducted.