Cytokine modulation by endothelin-1 and possible therapeutic implications in systemic sclerosis

Systemic sclerosis (SSc), also known as scleroderma, is an autoimmune disorder characterized by a progressive fibrosis which involves skin and internal organs, caused by microvascular damage. The earliest clinical sign of the disease is Raynauds Phenomenon, a vasospastic response to cold or stress stimuli, followed by the skin and organ involvement over time. This kind of vascular manifestation originates from the microvascular structural alteration, characterized by an abnormal myocyte cell proliferation, intima cell proliferation and adventitia fibrosis. The microvascular damage seems to be the consequence of the autoimmune attack to the endothelium, followed by inflammatory cascade and massive deposition of collagen. From the beginning of the disorder, serum Endothelin-1 (ET- 1) is found in very high concentration: this protein, today, is considered one of the most important mediators of scleroderma vascular alterations. Furthermore, many recent studies have shown that ET-1 is involved in the inflammatory and fibrotic processes, increasing the concentration of pro-fibrotic and pro-inflammatory cytokines. The aim of this review is to clarify the ET-1 role in SSc, in particular the relationship between ET-1 and cytokine expression, adding another element to the understanding of scleroderma disease.