Abstract
BACKGROUND AND PURPOSE: The majority of the severe vascular complications in fibrosis are a consequence of a deregulated activity of mediators controlling vasomotor tone. One of the most important of these mediators is endothelin-1 (ET-1). Here, we have investigated the role of proteinase-activated receptor 2 (PAR2) in the vascular dysfunction in a model of fibrosis, using tight-skin (Tsk) mice. EXPERIMENTAL APPROACH: Aortas were collected from Tsk, transgenic over-expressing PAR2 (TgPAR2), PAR2 deficient (PAR2(-/-) ) or the corresponding WT mice. Histological and immunohistochemistry analysis for α-smooth muscle actin, PAR2 and ET-1 receptors were performed on aorta sections. Vascular responses to phenylephrine, ET-1 and PAR2 activating peptide (PAR2-AP) were assessed on aortic rings. KEY RESULTS: In aortas from Tsk mice, responses to phenylephrine were reduced, contractions to ET-1 were increased and vasorelaxation to PAR2-AP was enhanced. These alterations matched changes observed in whole vessel architecture such as vascular fibre re-organization, increased collagen deposition and enhanced α-smooth muscle actin expression. Expression of both ET(A) receptors and PAR2 was enhanced in Tsk mice. Antagonism of PAR2 potentiated vascular effects of ET-1, whereas antagonism of ET(A) receptors increased vasorelaxation induced by PAR2-AP. In TgPAR2 mice, responses to ET-1 and ET-1 plasma levels were reduced. Conversely, PAR2(-/-) mice showed enhanced ET-1 induced contraction in aortic rings and higher circulating ET-1 levels. CONCLUSIONS AND IMPLICATIONS: Our data show that PAR2 counterbalanced enhanced contractions to ET-1 in aortas from Tsk mice. PAR2 could represent a possible target for novel drugs in the treatment of vascular complications in fibrosis. LINKED ARTICLES: This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.