Giant cell arteritis: update on pathogenesis and clinical implications

Purpose of review Giant cell arteritis (GCA) is an age-related autoimmune disease with a complex pathogenesis that involves several pathogenic mechanisms. This review provides recent critical insights into novel aspects of GCA pathogenesis. Recent findings The use of novel approaches, including multiomic techniques, has uncovered notable findings that broaden the understanding of GCA pathogenesis. TCF1 hi CD4 + T cells have been identified as stem-like T cells residing in tertiary lymphoid structures in the adventitia of GCA aortic tissues, which likely supply the pathogenic effector T cells present in vasculitic lesions. Studies have demonstrated that fibroblasts present in GCA-inflamed arteries are not innocent bystanders, but they contribute to arterial inflammation via maintenance of Th1 and Th17 polarisation, cytokine secretion (IL-6, IL-1B, IL-12, and IL-23) and antigen presentation. Additionally, deregulated cellular senescence programs are present in GCA as an accumulation of IL-6 and matrix metalloproteinase 9-producing senescent cells have been identified in vasculitic lesions. Summary Recent studies have unravelled interesting findings with potentially significant clinical relevance. Stem-like T cells are likely key contributors to vascular disease persistence, and targeted depletion or modulation of these cells holds promise in GCA management. Fibroblast-targeting therapies and senotherapeutics are also exciting prospects in the treatment of GCA.