The Biological Effects of Interleukin-17A on Adhesion Molecules Expression and Foam Cell Formation in Atherosclerotic Lesions

Interleukin-17A (IL-17A), a major effector cytokine secreted by T helper 17 (Th17) cells, is elevated in atherosclerosis lesions. The purpose of this study was to assess the role of IL-17A in the pathogenesis of atherosclerosis. To measure the expression of adhesion molecules, human umbilical vein endothelial cells (HUVECs) and U937 cells were stimulated with IL-17A. Western blot and real-time polymerase chain reaction analyses revealed that intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression in HUVECs, and very late antigen-4 (VLA-4), lymphocyte function-associated antigen-1 (LFA-1) and macrophage-1 antigen (MAC-1) expression in U937 cells was upregulated by IL-17A. Furthermore, IL-17A stimulation resulted in mRNA and protein expression of scavenger receptor (LOX-1) in phorbol 12-myristate 13-acetate (PMA)-activated U937 cells. Oil Red O also demonstrated that IL-17A enhanced foam cell formation by PMA-activated U937 cells induced by oxidized low-density lipoprotein (ox-LDL), and this enhancement of ox-LDL-induced foam cell formation in IL-17A-treated U937 cells was downregulated by transfection of LOX-1 siRNA. These results indicated that IL-17A induced the expression of adhesion molecules, promoted the adherence of monocytes to vascular endothelial cells. IL-17A also stimulated ox-LDL-induced foam cell formation via upregulation of LOX-1 in activated macrophages. IL-17A may be responsible for the pathogenesis of atherosclerosis by inducing the adhesion of leukocytes to vascular endothelium and foam cell formation.