Requirements and mechanisms of alloantigen-induced cardiac allograft survival by cDC1s

Heart transplantation is currently the only treatment for advanced heart failure and as such, the volume of transplants performed globally continues to increase. Advances in surgical technique and immunosuppression have improved patient survival acutely, however the same cannot be said years after transplantation. Immune mediated pathologies such as chronic allograft vasculopathy result in graft failure and significant morbidity from prolonged use of immunosuppressant medication including renal dysfunction, diabetes, and malignancy continue to be experienced by patients. Thus, improved strategies to promote survival of the cardiac allograft are necessary. Much work has sought to identify cellular actors responsible for cardiac allograft rejection and tolerance. In the setting of rejection, the adaptive immune response has emerged in a leading role, specifically CD4+ and CD8+ T cells. Importantly, T cells are not solo performers but instead require instruction provided by antigen presenting cells, predominantly dendritic cells (DCs). Once considered a homogenous population, DCs are now recognized for their distinct ontogeny and functional roles which determine DC subset identity. Conventional DC 1 cells (cDC1s) are powerful mediators of the immune response and have been shown to be critical for promoting central tolerance. Yet no work on the subset specific role of cDC1s in solid organ transplantation or peripheral tolerance has been performed. Importantly, my preliminary data implicate cDC1s as necessary in donor-induced tolerization strategies that result in long term cardiac allograft survival. This proposal hypothesizes that during a donor-induced tolerance strategy, the cDC1 subset is necessary to promote peripheral immunological hyporesponsiveness towards cardiac allografts through innate processing of alloantigen and subsequent cDC1 transcriptional reprogramming. This hypothesis will be tested using mouse models of cDC1 deletion and heterotopic hea