Giant-Cell Arteritis: Immunopathogenic Mechanisms Involved in Vascular Inflammation and Remodeling

Abstract

Giant-cell arteritis (GCA) is a large-vessel granulomatous vasculitis in which aging, gender and genetics likely play a significant role. The association with polymorphisms in the major histocompatibility complex suggests that GCA may be an antigen-driven disease. Immunopathology studies performed with temporal artery biopsies from patients with GCA have generated relevant clues regarding to pathogenesis by indicating participation of Th1 and Th17-mediated pathways, a prominent role for macrophages in tissue injury, and the relevance of vascular response to inflammation. Vascular wall elements, especially endothelial cells and vascular smooth muscle cells are not passive bystanders. Through expression of chemokines and adhesion molecules vascular cells contribute to the continuous recruitment of inflammatory cells that are able to enter the artery wall through newly formed neovessels. Inflammatory cell products, as well as vascular injury, trigger a vascular remodelling process. This eventually leads to the development of intimal hyperplasia and vascular lumen obliteration, source of ischemic complications.