Innate Immune Memory Responses in Organ Transplantation

Innate immunity is a critical contributor to graft rejection and cardiovascular complications after organ transplantation, with increasing evidence indicating that innate immune memory significantly influences graft outcomes. The most extensively studied form, trained immunity, involves epigenetic and metabolic reprogramming of innate immune cells, altering their inflammatory responsiveness. Numerous transplantation-related factors, including metabolic disturbances such as hypercholesterolemia and hyperglycemia, can induce trained immunity, and both experimental and clinical studies have linked it to graft survival. Although trained immunity reflects responses to nonspecific stimuli, innate allogeneic memory shows that innate immune cells can recognize nonself and mount donor-specific memory responses. This review covers the current knowledge on both forms of innate immune memory in the context of solid organ transplantation.