Pivotal Role of Mouse Mast Cell Protease 4 in the Conversion and Pressor Properties of Big-Endothelin-1

Abstract

The serine protease chymase has been reported to generate intracardiac angiotensin-II (Ang-II) from Ang-I as well as an intermediate precursor of endothelin-1 (ET-1), ET-1 (1-31) from Big-ET-1. Although humans possess only one chymase, several murine isoforms are documented, each with its own specific catalytic activity. Among these, mouse mast cell protease 4 (mMCP-4) is the isoform most similar to the human chymase for its activity. The aim of this study was to characterize the capacity of mMCP-4 to convert Big-ET-1 into its bioactive metabolite, ET-1, in vitro and in vivo in the mouse model. Basal mean arterial pressure did not differ between wild-type (WT) and mMCP-4(2/2) mice. Systemic administration of Big-ET-1 triggered pressor responses and increased blood levels of immunoreactive (IR) ET-1 (1-31) and ET-1 that were reduced by more than 50% in mMCP-4 knockout (2/2) mice compared with WT controls.Residual responses to Big-ET-1 in mMCP-4(2/2) mice were insensitive to the enkephalinase/neutral endopeptidase inhibitor thiorphan and the specific chymase inhibitor TY-51469 {2-[4-(5-fluoro-3-methylbenzo[b]thiophen-2-yl)sulfonamido-3-methanesulfonylphenyl]thiazole-4-carboxylic acid}. Soluble fractions from the lungs, left cardiac ventricle, aorta, and kidneys of WT but not mMCP-4(2/2) mice generated ET-1 (1-31) from exogenous Big-ET-1 in a TY-51469-sensitive fashion as detected by high-performance liquid chromatography/ matrix-assisted laser desorption/ionization-mass spectrometry. Finally, pulmonary endogenous levels of IR-ET-1 were reduced by more than 40% in tissues derived from mMCP-4(2/2) mice compared with WT mice. Our results show that mMCP-4 plays a pivotal role in the dynamic conversion of systemic Big-ET-1 to ET-1 in the mouse model.

The controversial role of mast cells in fibrosis

“…Mechanistically, it was shown that chymase inhibition led to a decrease in the content of TGFβ and MMP2 in the lungs, and it was demonstrated that chymase inhibition prevented effects of endothelin‐1. The latter observation is thus in agreement with a previous study where chymase was shown to be pivotal for the conversion of Big‐endothelin‐1 to endothelin‐1 . Chymase inhibition (using TY‐51469) has also been shown to dampen liver fibrosis in hamsters fed on a methionine‐ and choline‐deficient diet, and it was demonstrated that chymase inhibition attenuated the induction of angiotensin II and collagen expression in comparison with placebo‐treated animals .…”

“…The latter observation is thus in agreement with a previous study where chymase was shown to be pivotal for the conversion of Big-endothelin-1 to endothelin-1. 230 Chymase inhibition (using TY-51469) has also been shown to dampen liver fibrosis in hamsters fed on a methionine-and choline-deficient diet, and it was demonstrated that chymase inhibition attenuated the induction of angiotensin II and collagen expression in comparison with placebo-treated animals. 231 In addition, chymase inhibition using various compounds has been demonstrated to reduce cardiac fibrosis and Ang II production in diabetic hamsters, 232 cardiac fibrosis after ischemia reperfusion injury, 233 silica-induced pulmonary fibrosis in mice, 234 CCl 4 -induced liver fibrosis in hamsters, 235 tubulointerstitial fibrosis in obstructed kidneys in hamsters, 236 cardiac fibrosis in rats subjected to ligation of the left anterior descending coronary artery, 237 cardiac fibrosis in cardiomyopathic hamsters 238 and cardiac fibrosis in dogs subjected to tachycardia-induced heart failure.…”

Mouse Mast Cell Protease 4 Deletion Protects Heart Function and Survival After Permanent Myocardial Infarction

“…ET-1 is also a major factor involved in myocardial infarction pathophysiology and is a critical factor in pulmonary hypertension, a possible complication of heart failure ( Sakai et al, 1996 ). Finally our group demonstrated the role of mMCP-4 in the endogenous pulmonary synthesis of ET-1 in vivo ( Houde et al, 2013 ). Therefore, in light of the beneficial role of chymase inhibitors in other rodent models of heart failure, we hereby hypothesized that specific mMCP-4 activity repression would protect mice from PMI.…”

“…The closest mouse analog to human chymase, in terms of localization, substrate specificity and storage properties is mMCP-4 ( Pejler et al, 2010 ). Furthermore, chymase activity in the mouse heart is primarily due to mMCP-4 expression ( Houde et al, 2013 ). Cardiovascular targets of chymase in mice and humans include the activation of angiotensin-II (Ang-II), endothelin-1 (ET-1) and matrix metalloproteinase 9 (MMP-9) as well as the degradation of the matrix protein fibronectin ( Balcells et al, 1997 ; Houde et al, 2013 ; Semaan et al, 2015 ; Caughey, 2016 ).…”

Mouse connective tissue mast cell proteases tryptase and carboxypeptidase A3 play protective roles in itch induced by endothelin-1

“…Chymase has the capability to produce ET-1 by cleaving the precursor peptide Big-ET-1 in vivo [58]. Chymase has also been reported to cleave known itch mediators such as interleukins 6, 13, and 33 (IL-6, IL-13, IL-33 [59,60]) as well as substance P and VIP [41][42][43].…”