Knockout of endothelin type B receptor signaling attenuates bleomycin-induced skin sclerosis in mice

BACKGROUND: Endothelin-1 (ET-1) is important in the pathogenesis of systemic sclerosis (SSc). ET-1 binds two receptors, endothelin type A (ET(A)) and endothelin type B (ET(B)). Dual ET(A)/ET(B) receptor antagonists and a selective ET(A) receptor antagonist are used clinically to treat SSc, and the effect of these antagonists on fibroblast activation has been described. However, the role of ET(B) receptor signaling in fibrogenesis is less clear. This study was conducted to evaluate the profibrotic function of ET(B) receptor signaling in a murine model of bleomycin (BLM)-induced scleroderma. METHODS: We used ET(B) receptor–knockout (ET(B)KO) mice, which are genetically rescued from lethal intestinal aganglionosis by an ET(B) receptor transgene driven by the human dopamine β-hydroxylase (DβH)-gene promoter, and wild-type mice with DβH-ET(B) (WT). BLM or phosphate-buffered saline (PBS) was administered subcutaneously by osmotic minipump, and skin fibrosis was assessed by dermal thickness, subcutaneous fat atrophy, and myofibroblast count in the dermis. Dermal fibroblasts isolated from ET(B)KO and WT mice were cultured in vitro, stimulated with BLM or ET-1, and the expression of profibrotic genes was compared by quantitative PCR. RESULTS: Dermal thickness, subcutaneous fat atrophy, and myofibroblast counts in the dermis were significantly reduced in ET(B)KO mice compared to WT mice, after BLM treatment. Compared with wild-type, dermal fibroblasts isolated from ET(B)KO mice showed lower gene expressions of α-smooth muscle actin and collagen 1α1 in response to BLM or ET-1 stimulation in vitro. CONCLUSIONS: ET-1–ET(B) receptor signaling is involved in skin sclerosis and in collagen synthesis by dermal fibroblasts. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13075-016-1011-4) contains supplementary material, which is available to authorized users.