Prostacyclin analogue beraprost inhibits cardiac fibroblast proliferation depending on prostacyclin receptor activation through a TGF β-Smad signal pathway.

Yun Chen,Hongyan Zhu,Wenjuan Yao,Xiaole Xu,Guoliang Meng,Wei Zhang,Shengju Yang,Thomas H Thatcher

doi:10.1371/journal.pone.0098483

Yun Chen, Hongyan Zhu + Show 6 more

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https://doi.org/10.1371/journal.pone.0098483

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Abstract

Previous studies showed that prostacyclin inhibited fibrosis. However, both receptors of prostacyclin, prostacyclin receptor (IP) and peroxisome proliferator-activated receptor (PPAR), are abundant in cardiac fibroblasts. Here we investigated which receptor was vital in the anti-fibrosis effect of prostacyclin. In addition, the possible mechanism involved in protective effects of prostacyclin against cardiac fibrosis was also studied. We found that beraprost, a prostacyclin analogue, inhibited angiotensin II (Ang II)-induced neonatal rat cardiac fibroblast proliferation in a concentration-dependent and time-dependent manner. Beraprost also suppressed Ang II-induced collagen I mRNA expression and protein synthesis in cardiac fibroblasts. After IP expression was knocked down by siRNA, Ang II-induced proliferation and collagen I synthesis could no longer be rescued by beraprost. However, treating cells with different specific inhibitors of PPAR subtypes prior to beraprost and Ang II stimulation, all of the above attenuating effects of beraprost were still available. Moreover, beraprost significantly blocked transforming growth factor β (TGF β) expression as well as Smad2 phosphorylation and reduced Smad-DNA binding activity. Beraprost also increased phosphorylation of cAMP response element binding protein (CREB) at Ser133 in the nucleus. Co-immunoprecipitation analysis revealed that beraprost increased CREB but decreased Smad2 binding to CREB-binding protein (CBP) in nucleus. In conclusion, beraprost inhibits cardiac fibroblast proliferation by activating IP and suppressing TGF β-Smad signal pathway.

Highlights

Cardiac fibrosis, characterized by an increased collagen concentration or altered collagen composition in myocardium, enhances myocardial stiffness and hampers systolic ejection, which is a common feature in patients with advanced cardiac failure regardless of the aetiology of cardiomyopathy [1]
Similar experiments indicated that preincubation with beraprost (10 mM) for 4 h or 12 h remarkably inhibited proliferation of cardiac fibroblasts (CFs) induced by angiotensin II (Ang II) (Fig. 1C and 1D)
For many decades prostacyclin has been recognized as a key player in cardiovascular homeostasis, with numerous studies demonstrating a clear role for prostacyclin in the pathologic response of fibrosis

Summary

Introduction

Cardiac fibrosis, characterized by an increased collagen concentration or altered collagen composition in myocardium, enhances myocardial stiffness and hampers systolic ejection, which is a common feature in patients with advanced cardiac failure regardless of the aetiology of cardiomyopathy [1] It is one of the major biological determinants for fatal issues in cardiovascular diseases [2]. Cicaprost was effective in preventing TGF-b induced up-regulation of collagen I and other extracellular matrix related genes in mouse cardiac fibroblasts [16]. Taken together, these findings have detailed a role for prostacyclin in cardiac fibroblasts

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