Bosentan fosters microvascular de-remodelling in systemic sclerosis

Bosentan, a dual endothelin receptor antagonist, may reduce blood pressure by blocking the vasoconstrictor effect of endothelin-1. In systemic sclerosis (SSc) nailfold videocapillaroscopy (NVC); allows diagnostic and follow-up of microvascular damage. Distinct NVC patterns have been identified for the evaluation of severity of SSc microvascular damage. The objective of this study is to evaluate the modification of the microvasculature under Bosentan therapy in SSc patients with pulmonary arterial hypertension (PAH). Nine patients with PAH related to SSc in New York Heart Association classes III-IV were treated with Bosentan 125 mg twice a day. NVC optical probe videocapillaroscopy equipped with 100× and 200× contact lenses and connected to image analyse software was performed before and after 12 months of Bosentan therapy to evaluate the modification of microvasculature. Nine PAH SSc patients treated with Iloprost were used as controls. Before Bosentan therapy, seven patients showed at NVC severe loss of capillaries with large avascular areas and vascular architectural disorganisation which are typically "late" SSc pattern. After 12 months of Bosentan, NVC pattern changed in seven patients from "late" into "active" SSc pattern. The disappearance of avascular areas and capillary haemorrhages was the most striking result. Two patients had an "active" SSc pattern, not modified by Bosentan treatment. These data show that Bosentan may improve NVC pattern in SSC and the presence of new capillaries suggests that it may favour angiogenesis. Bosentan may improve and stabilise the microvasculature in long-term treatment modulating the structural modifications detected by NVC.