Project Grant R01AI189709

The National Institute of Allergy and Infectious Diseases awarded the University of Maryland, Baltimore $770,199 on August 3, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to investigate how metabolic rewiring driven by gut microbiome changes influences immune outcomes in chronic cardiac transplant rejection.

The research employs a murine model of chronic cardiac rejection with full MHC mismatch and clinically relevant chronic immunosuppression to study how specific bacterial species and microbiota-regulated metabolic compounds affect alloimmunity and graft survival. The work demonstrates that anti-inflammatory bacteria such as Bifidobacterium improve long-term graft outcomes while pro-inflammatory species such as Desulfovibrio impair graft survival, each differentially affecting lymph node structure, lymphocyte trafficking, and regulatory T cell differentiation. These bacteria distinctively reprogram metabolic activities in the gut lumen and circulation, altering amino acid, carbohydrate, and nucleotide metabolism, and trimethylamine biosynthesis. Fecal microbiota transplantation from human cardiac transplant recipients with cardiac allograft vasculopathy produces pro-inflammatory responses in the murine model resembling those from pro-inflammatory bacterial species. The research hypothesizes that altered gut microbiome composition shifts the immune balance between regulatory T cells and effector T cells, thereby modulating transplant rejection.

Performance occurs in Baltimore, Maryland, with a period of performance from August 3, 2026, through July 31, 2031. This is a Project Grant assistance type.