Fecal microbiota transplantation increases colonic IL-25 and dampens tissue inflammation in patients with recurrent Clostridioides difficile

Abstract

Background: Clostridioides difficile infection (CDI) is the most common hospital-acquired infection in the United States. Antibiotic-induced dysbiosis is the primary cause of susceptibility and fecal microbiota transplantation (FMT) has emerged as an effective therapy for recurrence. We previously demonstrated in the mouse model of CDI that antibiotic-induced dysbiosis reduced colonic expression of IL-25, and that FMT protected in part by restoring gut commensal bacteria-mediated IL-25 signaling. Here we conducted a prospective clinical trial to test the impact of FMT on immunity, specifically testing in humans if FMT induced IL-25 expression in the colon. Methods: Subjects received colonic biopsies and blood sampling at the time of FMT and 60-days later. Colon biopsies were assayed for IL-25 by immunoassay, for mRNA by RNAseq, and for bacterial content by 16 S rDNA sequencing. High dimensional flow cytometry was also conducted on peripheral blood mononuclear cells pre- and post-FMT. Results: All 10 subjects who received FMT had no CDI recurrences over a 2 year follow-up post FMT. FMT increased alpha diversity of the colonic microbiota and was associated with several immunologic changes. The cytokine IL-25 was increased in colonic tissue. In addition, increased expression of homeostatic genes and repression of inflammatory genes was observed in colonic mRNA transcripts. Finally, circulating Th17 cells were decreased post-FMT. Conclusion: The increase in the cytokine IL-25 accompanied by decreased inflammation is consistent with FMT acting in part to protect from recurrent CDI via restoration of commensal activation of type 2 immunity.