Functions of cyclophilin A in atherosclerosis.

Cyclophilin A (CypA) is a ubiquitously distributed protein present both in intracellular and extracellular spaces. In atherosclerosis, various cells, including endothelial cells, monocytes, vascular smooth muscle cells and platelets, secrete CypA in response to excessive levels of reactive oxygen species. Atherosclerosis, a complicated disease, is the result of the interplay of different risk factors. Researchers have found that CypA links many risk factors, including hyperlipidemia, hypertension and diabetes, to atherosclerosis that develop into a vicious cycle. Furthermore, most studies have shown that secreted CypA participates in the developmental process of atherosclerosis via many important intracellular mechanisms. CypA can cause injury to and apoptosis of endothelial cells, leading to dysfunction of the endothelium. CypA may also induce the activation and migration of leukocytes, producing proinflammatory cytokines that promote inflammation in blood vessels. In addition, CypA can promote the proliferation of monocytes/macrophages and vascular smooth muscle cells, leading to the formation of foam cells and the remodelling of the vascular wall. Studies investigating the roles of CypA in atherosclerosis may provide new direction for preventive and interventional treatment strategies in atherosclerosis.