Treprostinil inhibits proliferation and extracellular matrix deposition by fibroblasts through cAMP activation

Abstract

Idiopathic pulmonary fibrosis (IPF) is characterized by peripheral lung fibrosis and increased interstitial extracellular matrix (ECM) deposition. In IPF, tumor growth factor (TGF)-β1 which is the major stimulus of ECM deposition, and platelet derived growth factor (PDGF)-BB is a potent stimulus of fibrosis. Thus, the effect of Treprostinil on TGF-ß1 and PDGF-induced fibroblast proliferation and ECM deposition was investigated. Human peripheral lung fibroblasts of seven IPF patients and five lung donors were stimulated by PDGF, or TGF-β1, or the combination. Cells were pre-incubated (30 min) with either Treprostinil, forskolin, di-deoxyadenosine (DDA), or vehicle. Treprostinil time dependently activated cAMP thereby preventing PDGF-BB induced proliferation and TGF-β1 secretion. Cell counts indicated proliferation; α-smooth muscle actin (α-SMA) indicted differentiation, and collagen type-1 or fibronectin deposition remodeling. Myo-fibroblast indicating α-SMA expression was significantly reduced and its formation was altered by Treprostinil. Collagen type-I and fibronectin deposition were also reduced by Treprostinil. The effect of Treprostinil on collagen type-I deposition was cAMP sensitive as it was counteracted by DDA, while the effect on fibronectin was not cAMP mediated. Treprostinil antagonized the pro-fibrotic effects of both PDGF-BB and TGF-β1 in primary human lung fibroblasts. The data presented propose a therapeutic relevant anti-fibrotic effect of Treprostinil in IPF.

GPCR-induced YAP activation sensitizes fibroblasts to profibrotic activity of TGFβ1

“…Alternatively, our findings in this study and in [18] provide rationale for the use of GPCR agonists of G αs -coupled receptors as treatments that actively trigger YAP/TAZ inactivation and thus will have an antifibrotic potential. This is supported by reports that activating IP receptor by selexipag, treprostinil and iloprost [18,[83][84][85][86][87][88][89], β2-adrenoreceptors by oladaterol [90], or melatonin receptors by melatonin [91] is antifibrotic in vitro and in animal fibrosis models, and at the same time inhibits YAP/TAZ [18,23,91].…”

Endothelial calpain systems orchestrate myofibroblast differentiation during wound healing

“…Exogenous PDGF-BB is clinically used to treat chronic wounds (4) and facilitates wound healing even in diabetic mice, accompanied by accelerated granulation tissue formation and fibrogenesis (27). PDGF-BB also facilitates ECM production by fibroblasts (28). Furthermore, Pdgfrb deletion diminishes migratory activity, mitotic responses, and cellular survival in dermal fibroblasts (29).…”

“…Therefore, PDGF-BB and its signaling axis are responsible for granulation tissue formation and re-epithelialization (1,3,5). Moreover, PDGF-BB induces a-smooth muscle actin in fibroblasts (28,30), thereby contributing to myofibroblast differentiation. Although our data show that endothelial calpain activity is indispensable for PDGFR-b signaling in wound sites, the mechanisms by which it regulates PDGFR-b signaling are currently unclear.…”

Diverse Pharmacology of Prostacyclin Mimetics: Implications for Pulmonary Hypertension

“…In addition, PGE 2 inhibits the transition of fibroblasts to myofibroblasts [80] and is capable of suppressing fibroblast proliferation and collagen synthesis through EP 2 receptor-mediated pathways [81]. Indeed, anti-fibrotic properties of treprostinil have been reported both in vivo (bleomycin-induced pulmonary fibrotic model) and in vitro (inhibition of TGF-βstimulated collagen production), though the receptor involved was not defined in these studies [82,83]. It should also be mentioned that some of the above effects can be replicated by EP 4 receptors [47,84], suggesting some overlapping function of EP 2 and EP 4 receptors in regulating fibroblast function.…”

“…The key question is whether prostanoid drugs used to treat PAH patients have positive effects on vascular remodelling associated with the abnormal proliferation of different cell types within the blood vessel wall. In vitro studies reported from a number of laboratories using vascular cells isolated from the lungs of patients with endstage disease suggest that they should do so in vivo [9,22,83,101]. Our own studies directly comparing the anti-proliferative properties of several clinically approved therapies in PASMCs from PAH patients showed hugely variable responses with the lowest dose to significantly inhibit cell proliferation varying some 10,000-fold from 0.1 nM for treprostinil up to 1 μM for the ET-1 receptor antagonist bosentan [117].…”