The Vessels Contribute to Fibrosis in Systemic Sclerosis

Microvascular damage, clinically expressed by Raynaud's phenomenon, is generally the first symptom of the disease and the injured vascular cells, both endothelial and perivascular, may transdifferentiate to myofibroblasts, thus leading to collagen deposition in the tissue and consequent fibrosis. Systemic sclerosis (SSc, scleroderma) is complex disease characterized by autoimmunity, vasculopathy, and fibrosis. It has been shown that microvascular damage may be the first symptom of SSc. Injured endothelial cells and pericytes may transdifferentiate into myofibroblasts, the cells responsible for fibrosis and collagen deposition in the tissue. Based on these factors, the process of myofibroblast generation may link two pivotal events of SSc: microvascular damage and fibrosis. Understanding the development, differentiation, and function of myofibroblasts is therefore crucial to individuate early pathogenetic events and develop new therapeutic target for SSc, a condition in which no disease-modifying agents are available. The aim of this review was to discuss the possible origins of myofibroblasts in SSc, highlighting the process of endothelial mesenchymal transition and pericytes to myofibroblast transition and to show how these events may contribute to pathogenesis of the disease.