Disturbed flow-induced Gs-mediated signaling protects against endothelial inflammation and atherosclerosis.

Akiko Nakayama,Guozheng Liang,Min Chen,Kenneth Anthony Roquid,Sarah Tonack,Lee S Weinstein,András Iring,Oliver J Müller,Stefan Offermanns,Julián Albarrán-Juárez

doi:10.1172/jci.insight.140485

Abstract

Atherosclerosis develops preferentially in areas of the arterial system, in which blood flow is disturbed. Exposure of endothelial cells to disturbed flow has been shown to induce inflammatory signaling, including NF-κB activation, which leads to the expression of leukocyte adhesion molecules and chemokines. Here, we show that disturbed flow promotes the release of adrenomedullin from endothelial cells, which in turn activates its Gs-coupled receptor calcitonin receptor–like receptor (CALCRL). This induces antiinflammatory signaling through cAMP and PKA, and it results in reduced endothelial inflammation in vitro and in vivo. Suppression of endothelial expression of Gαs, the α subunit of the G-protein Gs; CALCRL; or adrenomedullin leads to increased disturbed flow–induced inflammatory signaling in vitro and in vivo. Furthermore, mice with induced endothelial-specific deficiency of Gαs, CALCRL, or adrenomedullin show increased atherosclerotic lesions. Our data identify an antiinflammatory signaling pathway in endothelial cells stimulated by disturbed flow and suggest activation of the endothelial adrenomedullin/CALCRL/Gs system as a promising approach to inhibit progression of atherosclerosis.

Highlights

Atherosclerosis predisposes to myocardial infarction and stroke, which are leading causes of morbidity and mortality [1]
We have recently shown that laminar flow activates PIEZO1, which leads to the release of adrenomedullin from endothelial cells and subsequent activation of its Gs-coupled receptor calcitonin receptor–like receptor (CALCRL), resulting in cAMP formation and PKA-mediated eNOS phosphorylation in an AKT-independent manner [25]
A similar increase of flow-induced NF-κB activation, as well as IκBα degradation after knockdown of Gαs was observed in HUVECs (Figure 2, A and B). quantitative PCR (qPCR) using HUVECs showed that both knockdown of Gαs, as well as inhibition of PKA, increased expression of CCL2 and PDGFB (Figure 2, C and D and Supplemental Figure 1D), and incubation of cells with dibutyryl-cAMP, a membrane-permeable stable derivative of cAMP, suppressed inflammatory gene expression induced by disturbed flow (Figure 2C)

Summary

Introduction

Atherosclerosis predisposes to myocardial infarction and stroke, which are leading causes of morbidity and mortality [1] It is an inflammatory disorder of large- and medium-sized arteries, which is promoted by a variety of risk factors, including arterial hypertension, high plasma levels of LDL-cholesterol and triglycerides, diabetes mellitus, obesity, and sedentary life style [1,2,3]. In addition to these systemic factors, the local microenvironment strongly affects the development and progression of atherosclerosis, which preferentially develops in areas of disturbed blood flow such as branching points or curvatures of the arterial system [4,5,6]. Activation of integrin α5, in addition, results in inhibition of cAMP signaling through the activation of phosphodiesterase 4D (PDE-4D) [18]

Methods

Results

Conclusion