CGRP derived from cardiac fibroblasts is an endogenous suppressor of cardiac fibrosis

Abstract

Aims Aberrant activation of cardiac fibroblasts leads to cardiac fibrosis, and evolving evidences suggest that endogenous bioactive substances derived from cardiac fibroblasts regulate cardiac fibroblasts activation in an autocrine/paracrine manner. Here we first presented evidence that cardiac fibroblasts can synthesize and secrete calcitonin gene-related peptide (CGRP), therefore, this study aimed to investigate the role of cardiac fibroblasts-derived CGRP in cardiac fibroblasts activation and its regulative mechanism. Methods and results The abundantly expression of CGRP in rat, mouse, and human myocardium allowed us to explore the cellular origin of CGRP, and found that the cardiac CGRP was mainly derived from cardiac fibroblasts. Activating TRPA1 with a specific agonist allyl isothiocyanate promoted the synthesis and secretion of CGRP, as well as intracellular Ca2+. These effects were reversed by TRPA1-specific antagonist HC030031 and Ca2+ chelator BAPTA-AM. TGF-β1 was applied to induce the activation of cardiac fibroblasts, and found that TGF-β1 can increase the mRNA expression and secretion levels of CGRP in cardiac fibroblasts. Either CGRP8–37 (CGRP receptor antagonist) or α-CGRP small interfering RNA (siRNA) aggravated TGF-β1-induced proliferation, differentiation, collagen production, and instigated inflammation in cardiac fibroblasts. Moreover, TGF-β1-induced NF-κB activation including IκBα phosphorylation and p65 nuclear translocation were also promoted by CGRP8–37 and α-CGRP siRNA. NF-κB inhibitor pyrrolidinedithiocarbamate ammonium (PDTC) reversed the effects of CGRP8–37 on NF-κB activation. The promotive effects of CGRP8–37 on TGF-β1-induced activation of cardiac fibroblasts were all reversed by PDTC. Monocrotaline (MCT) induces pulmonary arterial hypertension, progressively leading to right ventricular fibrosis. This model of cardiac fibrosis was developed here to test the potentially beneficial effects of TRPA1 activation in vivo. The non-toxic TRPA1 agonist Cinnamaldehyde (CA) inhibited MCT-induced elevation in right ventricle systolic pressure, RV/LV + S, and right ventricular collagen accumulation, as well as down-regulation of CGRP. CA increased the synthesis and secretion of CGRP, and inhibited TGF-β1-induced activation in cardiac fibroblasts. Conclusion Our data suggested an autocrine role for cardiac fibroblasts-derived CGRP in suppressing activation of cardiac fibroblasts through inhibiting NF-κB activation. Increasing autocrine CGRP by activating TRPA1 can ameliorate cardiac fibrosis. These findings support the notion that CGRP derived from cardiac fibroblasts is an endogenous suppressor of cardiac fibrosis.

Roles of calcitonin gene-related peptide in the skin, and other physiological and pathophysiological functions

“…Interactions between CGRP and fibroblasts also occur in the heart. There is abundant expression of CGRP in rat, mouse, and human myocardium, and cardiac CGRP is mainly derived from cardiac fibroblasts ( Li et al., 2020 ). NF-κB signaling plays an integral part in cardiac fibroblast activation, seen in aortic coarctation and angiotensin II induced cardiac fibrosis ( Higashikuni et al., 2013 ; Thakur et al., 2014 ).…”

“…NF-κB signaling plays an integral part in cardiac fibroblast activation, seen in aortic coarctation and angiotensin II induced cardiac fibrosis ( Higashikuni et al., 2013 ; Thakur et al., 2014 ). Autocrine CGRP can inhibit TGFβ1-induced activation of the NF-κB signal pathway, and activation of TRPA1 alleviated cardiac fibrosis by stimulating synthesis and production of CGRP in cardiac tissues ( Li et al., 2020 ).…”

Ca2+ signalling in fibroblasts and the therapeutic potential of KCa3.1 channel blockers in fibrotic diseases

“…Human cardiac fibroblasts (Chatelier et al, 2012;Koivumaki et al, 2014;Li et al, 2009;Zhan et al, 2016) Voltage-gated K + channels Transient outward K + current, I to Delayed rectified K + currents: I K , I Kf Human and rat cardiac fibroblast Rook et al, 1992; Neonatal rat cardiac fibroblasts (Rook et al, 1992;Walsh & Zhang, 2008) Inward-rectifier K + channels K ir , IK v Human lung fibroblasts (Roach et al, 2013) Human cardiac fibroblasts (Aguilar et al, 2014;Li et al, 2009) Canine atrial fibroblasts (Benamer et al, 2009) ATP-activated K + channels K ATP Rat ventricular fibroblasts (Benamer et al, 2009) Human dermal fibroblasts (Bednarczyk et al, 2018) TRP channels TRPA1, TRPC1, TRPC3, TRPC4, TRPC6, TRPV4, TRPM2, TRPM7 Human and mouse lung fibroblasts (Hofmann et al, 2017;Rahaman et al, 2014;Wei et al, 2009;Yonezawa et al, 2016) Mouse proximal tubular cells (Mannaa et al, 2018) Human and rat hepatic stellate cells (Song et al, 2014) Human, rat, and mouse kidney fibroblasts (Saliba et al, 2015) Rat ventricular fibroblasts (Rose et al, 2007) Human, rat, and mouse cardiac fibroblasts (Chen et al, 2010;Du et al, 2010;Li et al, 2019;Mannaa et al, 2018;Oguri et al, 2014;Rahaman et al, 2014;Runnels et al, 2002;Saliba et al, 2015;Song et al, 2014) Cl − channels I Cl-swell , ClC-3, I Cl Human cardiac fibroblasts (Li et al, 2009;…”

“…Human, rat, and mouse cardiac fibroblasts (Chen et al, 2010; Du et al, 2010; Li et al, 2019; Mannaa et al, 2018; Oguri et al, 2014; Rahaman et al, 2014; Runnels et al, 2002; Saliba et al, 2015; Song et al, 2014)…”

Transient Receptor Potential Ankyrin Type-1 Channels as a Potential Target for the Treatment of Cardiovascular Diseases

“…Furthermore, monocrotaline (MCT) is used to induce pulmonary hypertension, which gradually led to right ventricular fibrosis. The non-toxic TRPA1 agonist cinnamaldehyde (CA) inhibits MCT-induced pulmonary hypertension, which increases the RVSP, RV/LV + S, and right ventricular collagen accumulation, and downregulation of CGRP ( Li et al, 2019 ). This indicates that TRPA1 activation has potential benefits in inhibiting TGF-β1-induced myocardial fibrosis.…”