Systemic Sclerosis: A Key Model of Endothelial Dysfunction.

Systemic sclerosis (SSc) is a heterogeneous disease characterized by vascular alterations, immune dysregulation, and fibrosis. Solid evidence supports the hypothesis that endothelial dysfunction is the key player in SSc vascular injury and a critical factor concurring to the initiation of SSc pathogenesis. This narrative review reports on persistent endothelial dysfunction, resulting from oxidative stress, autoimmunity, and impaired vascular repair, in the course of SSc, and how it can trigger and sustain fibrotic remodeling of various organs. In this paper, we also analyze the impact on SSc of impaired angiogenesis and vasculogenesis, diminished endothelial progenitor cell function, and endothelial-to-mesenchymal transition, which can collectively disrupt vascular homeostasis and promote myofibroblast activation. These pathologic events underlie the hallmark clinical manifestations, i.e., Raynaud's phenomenon, digital ulcers, pulmonary arterial hypertension, and scleroderma renal crisis. The review highlights how recognizing SSc as a paradigm of systemic endothelial dysfunction may reframe our understanding of its physiopathology, modify current therapeutic strategies, and unveil new therapeutic targets.