CKD is an independent risk factor for cardiovascular disease (CVD). The accumulation of uremic toxins in CKD induces oxidative stress and endothelial dysfunction. MicroRNA-92a (miR-92a) is induced by oxidative stress in endothelial cells (ECs) and involved in angiogenesis and atherosclerosis. We investigated a role for oxidative stress–responsive miR-92a in CKD. Our study of patients at three clinical sites showed increased serum miR-92a level with decreased kidney function. In cultured ECs, human CKD serum or uremic toxins (such as indoxyl sulfate), compared with non-CKD serum, induced the levels of miR-92a and suppressed the expression of miR-92a targets, including key endothelial-protective molecules. The antioxidant N-acetylcysteine inhibited these vasculopathic properties. In rats, adenine-induced CKD associated with increased levels of miR-92a in aortas, serum, and CD144⁺ endothelial microparticles. Furthermore, CD144⁺ microparticles from human uremic serum contained more miR-92a than those from control serum. Additional analysis showed a positive correlation between serum levels of miR-92a and indoxyl sulfate in a cohort of patients with ESRD undergoing hemodialysis. Collectively, our findings suggest that the uremic toxins accumulated in CKD can upregulate miR-92a in ECs, which impairs EC function and predisposes patients to CVD.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) affects cholesterol homeostasis by targeting hepatic LDL receptor (LDLR) for lysosomal degradation. Clinically, PCSK9 inhibitors effectively reduce LDL-cholesterol (LDL-C) levels and the incidence of cardiovascular events. Because microRNAs (miRs) are integral regulators of cholesterol homeostasis, we investigated the involvement of miR-483 in regulating LDL-C metabolism. Using in silico analysis, we predicted that miR-483-5p targets the 3′-UTR of PCSK9 mRNA. In HepG2 cells, miR-483-5p targeted the PCSK9 3′-UTR, leading to decreased PCSK9 protein and mRNA expression, increased LDLR expression, and enhanced LDL-C uptake. In hyperlipidemic mice and humans, serum levels of total cholesterol and LDL-C were inversely correlated with miR-483-5p levels. In mice, hepatic miR-483 overexpression increased LDLR levels by targeting Pcsk9 , with a significant reduction in plasma total cholesterol and LDL-C levels. Mechanistically, the cholesterol-lowering effect of miR-483-5p was significant in mice receiving AAV8 PCSK9-3′-UTR but not Ldlr -knockout mice or mice receiving AAV8 PCSK9-3′-UTR (ΔBS) with the miR-483-5p targeting site deleted. Thus, exogenously administered miR-483 or similarly optimized compounds have potential to ameliorate hypercholesterolemia.

Significance: Oxidative and inflammatory stresses (e.g., atheroprone flow and hyperlipidemia) induce innate immune responses in vascular endothelium, of which the assembly and activation of nucleotide oligomerization domain-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome constitute a core mechanism. We show that TNF-α receptor-associated factor-interacting protein with a forkhead-associated domain (TIFA) is a mediator of NLRP3 inflammasome in endothelium. The involved regulations include that sterol regulatory element-binding protein 2 transcriptionally induces TIFA (signal 1) and that phosphorylated TIFA causes higher-order assembly of NLRP3 inflammasome (signal 2). Given that sustained innate immune response/activation in endothelium is common to a variety of vascular impairments, TIFA-mediated NLRP3 inflammasome constitutes a pathway by which sustained oxidative and inflammatory stresses lead to dysfunctional endothelium.

Significance: This work identifies a mechanism by which atheroprone oscillatory shear and atheroprotective pulsatile shear differentially regulate microRNA (miR) biogenesis in the vascular endothelium. Nonphosphorylated nucleolin facilitates the maturation of miR-93 and miR-484, which in turn target Krüpple-like factor 2 and endothelial nitric oxide synthase mRNAs. The translational significance of these findings is provided by the identification of elevated levels of miR-93 and miR-484 in sera from patients with coronary artery disease.