Review Article Role of Endothelial to Mesenchymal Transition in the Pathogenesis of the Vascular Alterations in Systemic Sclerosis

Copyright © 2013 Sergio A. Jimenez. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The pathogenesis of Systemic Sclerosis (SSc) is extremely complex, and despite extensive studies, the exactmechanisms involved are not well understood. Numerous recent studies of early events in SSc pathogenesis have suggested that unknown etiologic factors in a genetically receptive host trigger structural and functional microvascular endothelial cell abnormalities. These alterations result in the attraction, transmigration, and accumulation of immune and inflammatory cells in the perivascular tissues, which in turn induce the phenotypic conversion of endothelial cells and quiescent fibroblasts into activated myofibroblasts, a process known as endothelial to mesenchymal transition or EndoMT. The activated myofibroblasts are the effector cells responsible for the severe and frequently progressive fibrotic process and the fibroproliferative vasculopathy that are the hallmarks of SSc.Thus, according to this hypothesis the endothelial and vascular alterations, which include the phenotypic conversion of endothelial cells into activated myofibroblasts, play a crucial role in the development of the progressive fibrotic process affecting skin andmultiple internal organs. The role of endothelial cell and vascular alterations, the potential contribution of endothelial to mesenchymal cell transition in the pathogenesis of the tissue fibrosis, and fibroproliferative vasculopathy in SSc will be reviewed here. 1