PERK inhibition mitigates restenosis and thrombosis - a potential low-thrombogenic anti-restenotic paradigm

Abstract

BackgroundDrug-eluting stents (DES) represent the main-stream management of restenosis following treatments of occlusive cardiovascular diseases. However, DES cannot eliminate instent restenosis yet exacerbate thrombogenic risks. To achieve dual inhibition of restenotic smooth muscle cell (SMC) de-differentiation/proliferation and thrombogenic endothelial cell (EC) dysfunction, a common target in both cell types, has been long-sought after. We evaluated the potential of protein kinase RNA-like endoplasmic reticulum kinase (PERK) as such a target for low-thrombogenic anti-restenotic intervention.Methods and ResultsWe used a rat angioplasty model of restenosis and a FeCl3-induced mouse model of thrombosis. Loss-or gain-of-function was achieved by PERK inhibition (GSK2606414, siRNA) or overexpression (adenovirus). Restenosis was robustly mitigated by GSK2606414 administered either via injected (i.v.) lesion-homing platelet membrane-coated nanoclusters or a perivascular hydrogel; it was enhanced by PERK transgene. Whereas PERK inhibition blocked, its overexpression exacerbated PDGF-induced human aortic SMC de-differentiation (reduced smooth muscle α-actin or αSMA) and proliferation (BrdU incorporation). Further, PERK activity promoted STAT3 activation but inhibited SRF transcriptional (luciferase) activity; its protein co-immunoprecipitated with STAT3 and also MRTF-A, the SRF activator for αSMA transcription. Importantly, PERK inhibition also prevented TNFα-induced impairment of human EC growth and upregulation of thrombogenic tissue factor, both in vitro and ex vivo. In vivo, oral gavage of GSK2606414 preserved ~50% of the normal blood flow 60 min after FeCl3-induced vascular injury.ConclusionsPERK inhibition is dual beneficial in mitigating restenosis and thrombosis, thus implicating a potential design for anti-restenotic intervention to overcome the thrombogenicity of DES.

PERK Inhibition Promotes Post-angioplasty Re-endothelialization via Modulating SMC Phenotype Changes

“…Recently we developed local delivery platforms for lesiontargeted application of the first-in-class PERK inhibitor, GSK2606414, which demonstrated both anti-restenotic and anti-thrombotic efficacies in rodent models. 15 Despite the endothelium friendliness and benefits we observed in our previous studies, the exact impact of PERK inhibition on the endothelium regeneration process in vivo, or reendothelialization, remained unknown. Using the thermosensitive gel technology for perivascular local delivery, here we further determined the impact of PERK inhibition on reendothelialization after endothelium denudation in the rat balloon angioplasty model ( Fig.…”

“…In our most recent report, we used an unbiased highthroughput drug screening approach designed to identify a common target for SMC inhibition yet preservation of EC viability. 15 We found that three of the top-scored hits were inhibitors of PERK, which represents an ER stress response pathway. In a follow-up study, we found that PERK could be targeted to block both restenosis and thrombosis in rodent models.…”

“…14 In our previous studies, we reported the striking outcomes of dual amelioration of restenosis and thrombosis after PERK inhibition in rodent models. 15 We also unveiled a pivotal role of PERK in promoting SMC phenotype changes, including dedifferentiation and hyperproliferation, and ultimately, the development of intimal hyperplasia. In addition, our data further suggested a previously unknown implication of PERK pathway in the thrombogenecity in vascular cells.…”

“…The same regimen has demonstrated outstanding anti-restenotic efficacy in rat angioplasty model in our most recent report. 15 Immediately after balloon angioplasty, the gel containing GSK2606414 was applied to the outside of the injured segment of the carotid artery and solidified right away. In the control group, equal volume of vehicle mixed in tri-block gel was applied.…”

“…In addition, our data further suggested a previously unknown implication of PERK pathway in the thrombogenecity in vascular cells. 15 Given the established contribution of phenotypically converted SMC to endothelial dysfunction, we were encouraged to launch the current study to explore the potential of facilitating reendothelialization via the blockade of PERK activity. We further investigated the underlying molecular basis that involves a novel PERK-mediated SMC-EC paracrine communication.…”