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.