Objective: Inflammation induced by muscle ischemia is involved in tissue repair and perfusion recovery in peripheral arterial disease (PAD) patients. Interleukin (IL)-22 is an inflammatory cytokine discovered in recent years and shows versatile functions; however, its role in PAD remains unknown. Here, we test whether IL-22 and its receptors are involved in angiogenesis in experimental PAD.
Methods and results: Both IL-22 and its receptor-IL-22 receptor 1(IL-22R1) were upregulated in muscle and endothelial cells after ischemia. In experimental PAD models, blocking IL-22 using IL-22 monoclonal antibody impaired perfusion recovery and angiogenesis; on the other hand, IL-22 treatment improved perfusion recovery. Ischemic muscle tissue was harvested 3 days after experimental PAD for biochemical test, IL-22 antagonism resulted in decreased Signal Transducer and Activator of Transcription (STAT3) phosphorylation, but did not alter the levels of VEGF-A or cyclic guanine monophosphate (cGMP) levels in ischemic muscle. In cultured endothelial cells, IL-22R1 was upregulated under simulated ischemic conditions, and IL-22 treatment increased STAT3 phosphorylation, endothelial cell survival and tube formation. Knock down of IL-22R1 or treatment with STAT3 inhibitor blunted IL-22-induced endothelial cell survival or tube formation.
Conculsion: Ischemia-induced IL-22 and IL-22R1 upregulation improves angiogenesis in PAD by inducing STAT3 phosphorylation in endothelial cells. IL-22R1 may serve as a new therapeutic target for PAD.
Keywords: Angiogenesis; Endothelial cells; IL-22R1; Interleukin-22; Peripheral arterial disease; Signal transducer and activator of transcription 3.
Copyright © 2018. Published by Elsevier Inc.