A new slow-releasing formulation of butyrate prolongs allograft survival

Abstract

Abstract The microbiota consists of diverse microbes producing metabolites that can influence the immune system locally as well as systemically. These bioactive metabolites (postbiotics) have therapeutic potential and may prove useful to facilitate graft acceptance. Short-chain fatty acids (SCFA) promote intestinal homeostasis and have been linked to health and disease. The Hubbell-Nagler laboratories at the University of Chicago have developed a micelle-based platform that can deliver the SCFA butyrate systemically, with long-term retention and induction of tolerogenic responses. We hypothesized that the administration of this butyrate formulation will improve graft survival by suppressing the alloimmune response. Our preliminary data showed that only oral delivery of the butyrate formulation prolonged survival of a C57Bl/6 male to female minor-mismatched skin graft significantly, whereas sub-cutaneous and intra-peritoneal administration were ineffective. Improved graft survival was associated with diminished production of TNFα by splenic and skin-draining lymph node myeloid cells upon LPS stimulation, suggesting that butyrate modulates the myeloid compartment to reduce levels of pro-inflammatory cytokines. The postbiotic also enhanced survival of a BALB/c to C57Bl/6 major-mismatched skin graft, without the use of immunosuppressive drugs, and resulted in lower levels of donor-specific alloantibodies. Prolonging the administration of butyrate post-transplantation ameliorated graft survival even further, confirming the micelle-based platform has therapeutic potential. Current efforts focus on determining if the butyrate formulation drives myeloid cell polarization toward an anti-inflammatory phenotype. This project was supported by grant NIH/NIAID 2R01AI115716