T cells in organ ischemia reperfusion injury

Abstract

Ischemia and reperfusion injuries occur in multiple clinical settings and contribute to organ dysfunction/failures. Despite the innate inflammatory immune nature, T cells that are critically involved in the pathogenesis of ischemia reperfusion injury (IRI), include not only CD4+ T cells, but also CD8+ and γδT cells. This review focuses on questions of how putative Ag-specific T cells are involved, which include whether they function in an Ag-dependent manner; how they function, cytokine-mediated or costimulatory molecule-mediated mechanisms; and whether different T-cell subsets, Th1, Th17, regulatory T cell (Treg), are all involved and play distinctive roles? Specific T-cell populations, such as effector memory CD4 T cells, promote inflammatory immune activation by ischemia reperfusion independent of their adaptive properties, that is Ag-independently. They function by secreting cytokines and expressing costimulatory molecules to either promote or inhibit innate immune activation, or facilitate tissue repair/homeostasis, as exemplified by Th1, Th17 or Th2, Treg cells, respectively. T-cell-targeted therapies need to be refined with strategies to maximally eliminate the proinflammatory but spare the anti-inflammatory/immune regulatory properties of T cells, for future clinical application to ameliorate IRI.