Mucosa-Associated Invariant T Cells Undergo Phenotypic Changes Following Fecal Microbiota Transplantation
Abstract
Fecal microbiota transplantation (FMT) has emerged as the most effective therapy for recurrent Clostridioides difficile infections (rCDI); yet the role of immune cells in the response to FMT remains poorly understood. Mucosa-associated invariant T (MAIT) cells are bacterial metabolite-reactive T cells found in the peripheral blood and mucosal tissues. We posited that MAIT cells are in the perfect position to respond to the influx of microbial metabolites associated with FMT. We collected peripheral blood from rCDI patients prior to FMT, 1-week post-FMT, and 1-month post-FMT, to explore if MAIT cell phenotypic characteristics or functions change following treatment. Following FMT, MAIT cells moved away from a state of exhaustion and displayed increased cytokine production. While pre-FMT MAIT cells were predominantly MAIT-17, post-FMT MAIT cells in some patients shifted to become neither MAIT-17, MAIT-1, nor MAIT-2. The data indicates that FMT may reverse MAIT cell exhaustion after a long battle with rCDI.