Macitentan slows down the dermal fibrotic process in systemic sclerosis: in vitro findings.

Systemic sclerosis (or scleroderma) is an autoimmune disease characterized by skin and internal organ fibrosis, caused by microvascular dysfunction. The microvascular damage seems to be a consequence of an endothelial autoimmune response, followed by activation of the inflammatory cascade and massive deposition of collagen. Endothelin-1 (ET-1) contributes to the inflammatory and fibrotic processes by increasing the concentration of pro-inflammatory and pro-fibrotic cytokines, and it is considered one of the most relevant mediators of vascular damage in scleroderma. It is indeed found in very high concentration in serum of sclerodermic patients. Moreover, in these pathological conditions there is an increased expression of ET-1 receptors (ETA and ETB), which mediate the detrimental action of ET-1, and often a change of ETA/ETB ratio. The aim of the present study is to evaluate the in vitro effect of macitentan, an orally active tissue-targeting dual endothelin receptor antagonist, and its major metabolite (ACT-132577) on alpha smooth muscle actin (alphaSMA) expression, evaluated on dermal fibroblasts from healthy subjects and on dermal fibroblasts from lesional and non-lesional skin from sclerodermic patients. The combination of macitentan and its major metabolite reduced the levels of αSMA after 48 h in sclerodermic fibroblasts from lesional skin. No relevant changes in αSMA levels were found in fibroblasts from non-lesional skin, whose behavior is similar to that of dermal fibroblasts from healthy patients.

Evaluation of the effect of Bosentan treatment on proinflammatory cytokine serum levels in patients affected by Systemic Sclerosis.

Systemic sclerosis (SSc) is a connective tissue disease characterized by vascular and fibrotic changes in the skin and in internal organs. Endothelin-1 (ET-1) is a peptide that has a role in promoting both vascular injury and the fibrotic process in SSc; indeed, patients with systemic sclerosis have higher levels of ET-1 compared with healthy subjects. Moreover, ET-1 enhances expression of pro-inflammatory cytokines in animal model. Bosentan is a dual endothelin receptor antagonist approved for the treatment of pulmonary arterial hypertension and digital ulcers in scleroderma patients. In animal models and in vitro models, after treatment with Bosentan, a significant reduction of cytokine (TNF α, IFN γ,IL-8, IL-4) levels was observed. The aim of the study is to verify whether Bosentan treatment in SSc patients can reduce circulating cytokines levels. We enrolled 10 patients affected by SSc with digital ulcers and/or pulmonary hypertension, treated with Bosentan 125 mg twice daily. Patients were tested for cytokines and ET-1 level before treatment and after 12 months. The cytokines tested were IL-10, IL-2, IL-4, IL-5, IL-6, IL-8, GM-CSF, IFN-γ and TNF. Levels of ET-1, IL-10, IL-4, IL-5, GM-CSF and TNFalpha did not show consistent modification during treatment with Bosentan in respect to baseline, while IL-2, IL-6, IL-8 and IFN-γ were significantly decreased. Bosentan significantly reduced IL-2, IL-6, IL-8 and IFN- γ levels in SSc patients, probably slowing progression to fibrosis and vascular damage. This is the first report showing a decrease of profibrotic and proinflammatory cytokines levels in humans during treatment with Bosentan.

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.