Inhibition of leptin-induced vascular extracellular matrix remodelling by adiponectin.

Zhi Zhang,Qunan Cao,Guang Chu,Fang Wang,Bing-jian Wang,Qiu-Yan Dai,Bao-Gui Sun

doi:10.1530/jme-14-0027

Abstract

Vascular extracellular matrix (ECM) remodelling, which is the result of disruption in the balance of ECM synthesis and degradation, induces vessel fibrosis and thereby leads to hypertension. Leptin is known to promote tissue fibrosis, while adiponectin has recently been demonstrated to be anti-fibrogenic in tissue fibrosis. In this study, we aimed to evaluate the leptin-antagonist function of adiponectin and to further elucidate the mechanisms through which adiponectin dampens leptin signalling in vascular smooth muscle cells, thus preventing excess ECM production, in our already established 3D co-culture vessel models. Our 3D co-culture vessel model, which mimics true blood vessels, is composed of vascular endothelial cells, vascular smooth muscle cells and collagen type I. We validated the profibrogenic effects of leptin and analysed matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor of metalloproteinase 1 (TIMP1) and collagen types II/IV secretion in 3D vessel models. The protective/inhibitory effects of adiponectin were re-analysed by inhibiting adiponectin receptor 1 (AdipoR) and AdipoR2 expression in endothelial cells using RNAi technology. In the 3D vessel models, adiponectin blocked the leptin-stimulated secretion of collagen types II/IV and TIMP1 while significantly increasing MMP2/9 activity. In endothelial cells, adiponectin induced phosphorylation of AMPK, thereby suppressing leptin-mediated STAT3 phosphorylation through induction of SOCS3 in smooth muscle cells. Our findings indicate that adiponectin disrupted the leptin-induced vascular ECM remodelling via AdipoR1 and enhanced AMPK signalling in endothelial cells, which, in turn, promoted SOCS3 up-regulation in smooth muscle cells to repress leptin-stimulated phosphorylation of STAT3.

Highlights

While obesity has become a major public health concern, in adolescents, the prevalence of hypertension has been increasing (Egan et al 2010, Shay et al 2013, Zhao et al 2013)
We investigated the effect of different cellular signal transduction modulators on the expression of collagen types II/IV, tissue inhibitor of metalloproteinase 1 (TIMP1), matrix metalloproteinase 2 (MMP2) and MMP9 in the 3D models treated with both leptin and adiponectin
One of the primary advantages of employing our established 3D model in this study was the ability to analyse the interaction between endothelial cells and smooth muscle cells, which is difficult to achieve with traditional 2D cell culture systems, which that pose major technical challenges

Summary

Introduction

While obesity has become a major public health concern, in adolescents, the prevalence of hypertension has been increasing (Egan et al 2010, Shay et al 2013, Zhao et al 2013). Fibrosis has been attributed to extracellular matrix (ECM) remodelling, which is the result of disruption in the balance between ECM synthesis and degradation. Arterial remodelling implicated in hypertension is associated, at least in part, with vascular ECM remodelling (Lemarie et al 2010). ECM remodelling is largely determined by the rate of collagen synthesis and the balance of the degradative enzymes – matrix metalloproteinases (MMPs) – with respect to a highly regulated multifunctional endogenous tissue inhibitor, the tissue inhibitor of metalloproteinases (TIMPs; Fedak et al 2005). Leptin suppresses the expression and activity of the collagen-degrading MMPs, such as MMP2, and promotes the expression of TIMP1, an important negative regulator of MMP2 (Cao et al 2007). The role of leptin in vascular ECM remodelling remains unclear

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