Indoxyl sulfate-induced activation of (pro)renin receptor promotes cell proliferation and tissue factor expression in vascular smooth muscle cells.

Maimaiti Yisireyili,Kyosuke Takeshita,Toyoaki Murohara,Fuyuhiko Nishijima,Yelixiati Adelibieke,Shaniya Abudureyimu,Shinichi Saito,Hwee-Yeong Ng,Toshimitsu Niwa,Rudolf Kirchmair

doi:10.1371/journal.pone.0109268

Abstract

Chronic kidney disease (CKD) is associated with an increased risk of cardiovascular disease (CVD). (Pro)renin receptor (PRR) is activated in the kidney of CKD. The present study aimed to determine the role of indoxyl sulfate (IS), a uremic toxin, in PRR activation in rat aorta and human aortic smooth muscle cells (HASMCs). We examined the expression of PRR and renin/prorenin in rat aorta using immunohistochemistry. Both CKD rats and IS-administrated rats showed elevated expression of PRR and renin/prorenin in aorta compared with normal rats. IS upregulated the expression of PRR and prorenin in HASMCs. N-acetylcysteine, an antioxidant, and diphenyleneiodonium, an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase, suppressed IS-induced expression of PRR and prorenin in HASMCs. Knock down of organic anion transporter 3 (OAT3), aryl hydrocarbon receptor (AhR) and nuclear factor-κB p65 (NF-κB p65) with small interfering RNAs inhibited IS-induced expression of PRR and prorenin in HASMCs. Knock down of PRR inhibited cell proliferation and tissue factor expression induced by not only prorenin but also IS in HASMCs.ConclusionIS stimulates aortic expression of PRR and renin/prorenin through OAT3-mediated uptake, production of reactive oxygen species, and activation of AhR and NF-κB p65 in vascular smooth muscle cells. IS-induced activation of PRR promotes cell proliferation and tissue factor expression in vascular smooth muscle cells.

Highlights

Patients with chronic kidney disease (CKD) are at high risk for cardiovascular disease (CVD)
indoxyl sulfate (IS) is a metabolite of tryptophan derived from dietary protein, and is synthesized in the liver from indole that is produced by intestinal flora including Escherichia coli
CellTiter 96 Aqueous One Solution Cell Proliferation Assay was from Promega (Madison, WI, USA), and Lipofectamine RNA iMAX reagent was from Invitrogen (Life Technologies, Carsbad, CA, USA)

Summary

Introduction

Patients with chronic kidney disease (CKD) are at high risk for cardiovascular disease (CVD). CKD leads to accelerated atherosclerosis and to a marked increase in cardiovascular morbidity and mortality [1]. Accumulation of indoxyl sulfate (IS), a protein-bound uremic toxin, is involved in the progression of CKD, and CVD [2,3,4]. IS is a metabolite of tryptophan derived from dietary protein, and is synthesized in the liver from indole that is produced by intestinal flora including Escherichia coli. IS accumulates in serum due to its reduced renal clearance [2,5]. Because of its protein binding ability, removal by hemodialysis is not as efficient as that of non-protein bound uremic toxin. IS shows nephrotoxicity after its uptake by renal proximal tubular cells through the basolateral membrane via organic anion transporter 1 (OAT1) and OAT3 [6]

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Results

Discussion

Conclusion