The IL-17A/IL-17RA axis plays a proatherogenic role via the regulation of aortic myeloid cell recruitment

Abstract

RATIONALE:: Atherosclerosis is a disease of large- and medium-sized arteries that is characterized by chronic vascular inflammation. While the role of Th1, Th2, and T-regulatory subsets in atherogenesis is established, the involvement of IL-17A-producing cells remains unclear. OBJECTIVE:: To investigate the role of the IL-17A/IL-17RA axis in atherosclerosis. METHODS AND RESULTS:: We bred apolipoprotein-E-deficient (Apoe) mice with IL-17A-deficient and IL-17 receptor A-deficient mice to generate Il17aApoe and Il17raApoe mice. Western diet fed Il17aApoe and Il17raApoe mice had smaller atherosclerotic plaques in the aortic arch and aortic roots, but showed little difference in plaque burden in the thoracoabdominal aorta in comparison with Apoe controls. Flow cytometric analysis of Il17aApoe and Il17raApoe aortas revealed that deficiency of IL-17A/IL-17RA preferentially reduced aortic arch, but not thoracoabdominal aortic T cell, neutrophil, and macrophage content in comparison with Apoe aortic segments. In contrast to ubiquitous IL-17RA expression throughout the aorta, IL-17A was preferentially expressed within the aortic arch of WD-fed Apoe mice. Deficiency of IL-17A or IL-17RA reduced aortic arch, but not thoracoabdominal aortic TNFα and CXCL2 expression. Aortic vascular IL-17RA supports monocyte adherence to explanted aortas in ex vivo adhesion assays. Short-term homing experiments revealed that the recruitment of adoptively transferred monocytes and neutrophils to the aortas of Il17raApoe mice is impaired in comparison with Apoe recipients. CONCLUSIONS:: The IL-17A/IL-17RA axis increases aortic arch inflammation during atherogenesis through the induction of aortic chemokines, and the acceleration of neutrophil and monocyte recruitment to this site. © 2012 American Heart Association, Inc.