Inhibition of Receptor-Interacting Protein Kinase 1 with Necrostatin\u20131s ameliorates disease progression in elastase-induced mouse abdominal aortic aneurysm model

Qiwei Wang,Jun Ren,Bo Liu,K Craig Kent,Kartik Gupta,Stephanie Morgan,Carmel Assa,Zhenjie Liu,Noel Phan,Ting Zhou,Danielle M Stewart

doi:10.1038/srep42159

Abstract

Abdominal aortic aneurysm (AAA) is a common aortic disease with a progressive nature. There is no approved pharmacological treatment to effectively slow aneurysm growth or prevent rupture. Necroptosis is a form of programmed necrosis that is regulated by receptor-interacting protein kinases (RIPs). We have recently demonstrated that the lack of RIP3 in mice prevented aneurysm formation. The goal of the current study is to test whether perturbing necroptosis affects progression of existing aneurysm using the RIP1 inhibitors Necrostatin-1 (Nec-1) and an optimized form of Nec-1, 7-Cl-O-Nec-1 (Nec-1s). Seven days after aneurysm induction by elastase perfusion, mice were randomly administered DMSO, Nec-1 (3.2 mg/kg/day) and Nec-1s (1.6 mg/kg/day) via intraperitoneal injection. Upon sacrifice on day 14 postaneurysm induction, the aortic expansion in the Nec-1s group (64.12 ± 4.80%) was significantly smaller than that of the DMSO group (172.80 ± 13.68%) (P < 0.05). The mean aortic diameter of Nec-1 treated mice appeared to be smaller (121.60 ± 10.40%) than the DMSO group, though the difference was not statistically significant (P = 0.1). Histologically, the aortic structure of Nec-1s-treated mice appeared normal, with continuous and organized elastin laminae and abundant αActin-expressing SMCs. Moreover, Nect-1s treatment diminished macrophage infiltration and MMP9 accumulation and increased aortic levels of tropoelastin and lysyl oxidase. Together, our data suggest that pharmacological inhibition of necroptosis with Nec-1s stabilizes pre-existing aneurysms by diminishing inflammation and promoting connective tissue repair.

Highlights

Time between diagnosis and surgical intervention often exceeds 7 years
Using a pan caspase inhibitor Q-VD-Oph in Angiotensin II (Ang II)-induced abdominal aortic aneurysm (AAA) in apolipoprotein E knockout mice, we showed that smooth muscle cells (SMCs) apoptosis is essential for aneurysm formation but not required for aneurysm growth[17]
We investigated the role of RIP1 in aneurysm using another model in which aortic aneurysm formation in hypercholesterolemic Apoe−/− mice is induced by angiotensin II (Ang II) infusion for 28 days

Summary

Introduction

Time between diagnosis and surgical intervention often exceeds 7 years. establishing pharmacological treatments for small AAAs is both meaningful and urgent. Levels of RIP3 protein and mRNA are elevated in aortic SMCs of human and mouse aneurysmal tissues. Since Rip1−/− mice die perinatally, to study RIP1 in AAA, we turned to a group of anti-necroptosis small molecules represented by necrostatin-1 (Nec-1) that were discovered from a cell-based screen for chemical inhibitors of necroptosis in monocytic U932 cells[29]. Follow-up studies demonstrated that Nec-1 blocks necroptosis by inhibiting RIP1 kinase activity[21]. Rip[1] gene deletion is lethal[28], inhibition of RIP1 kinase by administration of Nec-1 to adult mice is safe and has been employed in many animal models of human diseases including ischemic brain injury[29], photoreceptor loss[30], and myocardial infarction[31]. Inhibiting RIP1 after aneurysm induction diminishes SMC death and local vascular inflammation, and promotes tissue repair mechanisms

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