Klotho Inhibits Proliferation and Migration of Angiotensin II-Induced Vascular Smooth Muscle Cells (VSMCs) by Modulating NF-κB p65, Akt, and Extracellular Signal Regulated Kinase (ERK) Signaling Activities

The anti-inflammatory properties of vinpocetine mediates its therapeutic potential in management of atherosclerosis

Atherosclerosis (AS) formation is enhanced by different mechanisms including cytokine generation, vascular smooth muscle cell proliferation, and migration. One of the recent treatments towards endothelial dysfunction and AS is Vinpocetine (VPN). VPN is a potent inhibitor of phosphodiesterase enzyme 1 (PDE-1) and has anti-inflammatory and antioxidant effects through inhibition the expression of nuclear factor kappa B (NF-κB). VPN has been shown to be effective against the development and progression of AS. However, the underlying molecular mechanism was not fully clarified. Consequently, objective of the present review was to discuss the mechanistic role of VPN in the pathogenesis AS. Most of pro-inflammatory cytokines that released from macrophages are inhibited by action of VPN through NF-κB-dependent mechanism. VPN blocks monocyte adhesion and migration by constraining the expression and action of pro-inflammatory cytokines. As well, VPN is effective in reducing of oxidative stress a cornerstone in the pathogenesis of AS through inhibition of NF-κB and PDE1. VPN promotes plaque stability and prevents the erosion and rupture of atherosclerotic plaque. In conclusion, VPN through mitigation of inflammatory and oxidative stress, and improvement of plaque stability effects could be effective agent in the management of AS.

Reduced Levels of the Antiaging Hormone Klotho are Associated With Increased Aortic Stiffness in Diabetic Kidney Disease

Introduction

Aortic pulse wave velocity (Ao-PWV) predicts cardiovascular and kidney disease in type 2 diabetes (T2D). Klotho is a circulating antiaging hormone (sKlotho) with putative cardiorenal protective effects. The relationship between sKlotho and Ao-PWV in diabetic kidney disease (DKD) is unknown.

Methods

In a cross-sectional cohort study, the correlation of sKlotho measured by a validated immunoassay, and Ao-PWV measured by applanation tonometry, was investigated in 172 participants with T2D and early stage DKD (all had estimated glomerular filtration rate [eGFR] >45 ml/min) on stable renin angiotensin system (RAS) inhibition. In cultured human aortic smooth muscle cells (HASMCs) stimulated with angiotensin II (AngII), the effects of recombinant human sKlotho pretreatment were assessed on intracellular calcium ([Ca²⁺]_i) responses and expression of proteins associated with proosteogenic HASMC phenotypes.

Results

Mean (range) age of the cohort was 61.3 years (40-82) and 65% were male. Mean (±SD) Ao-PWV was 11.4 (±2.3) m/s, eGFR 78.8 (±23.5) and median (interquartile range) sKlotho of 358.5 (194.2-706.3) pg/ml. In multivariable linear regression analyses, we observed a statistically significant inverse relationship between sKlotho and Ao-PWV, which was independent of clinical risk factors for cardiorenal disease. Pretreatment of cultured HASMC with sKlotho significantly attenuated AngII-stimulated [Ca²⁺]_i transients and reduced osteogenic collagen (Col1a2) expression.

Conclusions

In individuals with T2D and early DKD, lower levels of sKlotho are associated with increased Ao-PWV. Taken together with the direct effect of sKlotho on mediators of aortic wall stiffness in vitro, these findings may explain the enhanced risk of cardiorenal disease in DKD.

Valsartan Prevented Neointimal Hyperplasia and Inhibited SRSF1 Expression and the TLR4-iNOS-ERK-AT1 Receptor Pathway in the Balloon-injured Rat Aorta

Valsartan has the potential to attenuate neointimal hyperplasia and to suppress the inflammatory response. This study aimed to evaluate the role of valsartan in neointimal hyperplasia and the toll-like receptor 4 (TLR4)-nitric oxide synthase (NOS) pathway in the balloon-injured rat aorta.Forty-eight Wistar rats were randomly allocated to three groups: sham control (control), balloon-injured group (surgery), and balloon-injured+valsartan-treated group (valsartan). Rats were killed at 14 and 28 days after balloon-injury, and then the aortic tissues were collected for morphometric analysis as well as for measurements of the mRNA or protein expression of angiotensin II, angiotensin II type 1 (AT1) receptor, angiotensin II type 2 (AT2) receptor, TLR4, endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), serine/arginine-rich splicing factor 1(SRSF1) and extracellular signal regulated kinase (ERK). Valsartan at a dose of 20 mg/kg/day markedly decreased neointimal hyperplasia in the aorta of balloon-injured rats, and significantly reduced the mRNA or protein expression of TLR4, AT1 receptor, SRSF1 and phosphorylated-ERK (p-ERK) as well as the aortic levels of iNOS (all p < 0.05). Moreover, valsartan increased the eNOS level and AT2 receptor mRNA and protein expression levels (all p < 0.05). Valsartan prevented neointimal hyperplasia and inhibited SRSF1 expression and the TLR4-iNOS-ERK-AT1 receptor pathway in the balloon-injured rat aorta.

Resistin-like molecule beta augments phenotypic modulation of human aortic smooth muscle cell triggered by high glucose

Vascular muscle cells (VSMCs) participate in the pathophysiology of atherosclerosis. Resistin-like molecule beta (Relmβ) contributes to atherosclerosis development by activating macrophage. This study aims to investigate whether Relmβ regulates VSMC phenotypic modulation under high glucose environment. Human aortic vascular smooth muscle cells were cultured and treated with Relmβ in the presence or absence of high glucose. VSMC phenotypic modulation was assessed by expression of related markers. The migration of VSMCs was detected by wound healing assay and transwell assay. The proliferation of VSMCs was measured using CCK-8 assay. In this study, we observed that Relmβ modulated VSMC phenotypic modulation by down-regulating expression of smooth muscle α-actin (α-SMA), smooth muscle myosin heavy chain (SM-MHC), and calponin while up-regulating expression of osteopontin (OPN). Relmβ increased the expression of inflammatory genes in VSMCs. Relmβ also augmented VSMCs migration as well as proliferation. It is worth noting that all the effects of VSMCs were enhanced upon high glucose stimulation. The phosphorylation levels of p38MAPK and ERK1/2 were increased by co-treatment with Relmβ and high glucose. The p38 MAPK pathway inhibitor RWJ64809 and pERK1/2 inhibitor PD98059 significantly inhibited the proliferation of VSMCs induced by Relmβ and high glucose. Our results provide evidence that Relmβ augments phenotypic modulation and migration of human aortic smooth muscle cell induced by high glucose. Relmβ might be a potential target for treatment of atherosclerosis induced by hyperglycemia.

Danthron attenuates experimental atherosclerosis by targeting foam cell formation

NEW FINDINGS

What is the central question of this study? Does danthron alleviate experimental atherosclerosis by inhibiting the formation of foam cells? What are the main findings and their importance? Danthron improved serum lipid profiles and significantly reduced the atherosclerotic plaque areas and lipid accumulation in the aortic root of ApoE^-/- mice. Danthron inhibited foam cell formation in oxidized low-density lipoprotein-induced RAW264.7 macrophages. Furthermore, danthron exerted its function in atherosclerosis at least partly through activating the AMP-activated protein kinase-sirtuin 1 signalling pathway. These findings suggest that danthron has the potential to alleviate atherosclerosis.

ABSTRACT

Danthron, an ingredient isolated from Rheum palmatum L., has been revealed to reduce lipid accumulation in vitro. This study aimed to discover the effects of danthron on the development of atherosclerosis and to delineate the underlying mechanisms. For in vivo studies, male ApoE^-/- mice were fed a high-fat diet and orally treated with danthron (30 or 60 mg/kg/day) for 12 weeks. For in vitro studies, RAW264.7 cells were induced by oxidized low-density lipoprotein (ox-LDL, 50 μg/ml) for 48 h and subsequently administered danthron at appropriate concentrations for 24 h. AMP-activated protein kinase (AMPK) inhibitor compound C was added to ox-LDL-stimulated RAW264.7 cells 2 h before danthron administration to confirm the role of the AMPK signalling pathway in the regulation by danthron of foam cell formation. We found that danthron improved serum lipid profiles, and significantly reduced atherosclerotic plaque areas and lipid accumulation in the aortic root of atherosclerotic mice. Moreover, danthron upregulated the mRNA and protein expression of ATP-binding cassette transporter A1 (ABCA1), ABCG1 and liver X receptor α (LXRα), which play a crucial role in lipid metabolism, and activated the AMPK-sirtuin 1 (SIRT1) pathway. In an in vitro study, danthron inhibited foam cell formation in ox-LDL-induced RAW264.7 macrophages with an increase in the expression of ABCA1, ABCG1 and LXRα as well as activation of the AMPK-SIRT1 pathway. Furthermore, compound C abolished the effects of danthron on lipid accumulation and the protein expression of ABCA1/G1 and LXRα in vitro. Our results highlight that danthron possesses potential benefits in alleviating experimental atherosclerosis by targeting foam cell formation by activating the AMPK-SIRT1 signalling pathway.

The Protective Role of Klotho in CKD-Associated Cardiovascular Disease

Background

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality in advanced CKD. The major pathological changes of CKD-associated CVD are severe vascular media calcification, aberrant cardiac remodeling such as hypertrophy and fibrosis, as well as accelerated atherosclerosis. α-Klotho is proposed as an anti-aging gene, which is primarily expressed in the kidney. Recent studies reveal that α-Klotho deficiency is associated with profound cardiovascular dysfunction. Of note, CKD represents extremely declined α-Klotho levels, hinting that α-Klotho deficiency may be implicated in the pathogenesis of CKD-associated CVD.

Summary

Based on the pathogenic mechanism of α-Klotho deficiency and decreased Klotho levels in the circulation even early in stage 1 of CKD, α-Klotho serves as a sensitive biomarker for renal insufficiency and also a novel predictor of risk of overall mortality of CVD events in CKD. Meanwhile, loss of Klotho resulted from kidney dysfunction markedly contributes to the progressive development of CKD and CVD. By contrast, prevention of Klotho decline using exogenous supplementation or genetically activated ways by several mechanisms can dramatically mitigate cardiac dysfunction, prevent vascular calcification, and retard the progression of CKD-accelerated atherosclerosis.

Key Messages

Klotho deficiency is proposed as a novel predictive biomarker as well as a pathogenic contributor to CVD events in CKD. In the future, Klotho may be a crucial potential therapeutic strategy to decrease the burden of CVD comorbidity with CKD in clinics.

miR-18a-5p Promotes Proliferation and Migration of Vascular Smooth Muscle Cells by Activating the AKT/Extracellular Regulated Protein Kinases (ERK) Signaling Pathway

Background

microRNAs (miRNAs) play important roles in abnormal proliferation and migration of vascular smooth muscle cells (VSMCs), which lead to restenosis in coronary artery disease. Nevertheless, the role of miR-18a-5p and how it works in VSMCs remain unknown.

Material/Methods

miR-18a-5p expression was determined by fluorescence quantitative real-time polymerase chain reaction (qRT-PCR) analysis of tissues from 20 patients with stent restenosis, and rats with carotid artery injury, as well as VSMCs. A cell viability assay was used to measure cell proliferation. Cell migration abilities were assessed by transwell migration assay and wound healing assays. To identify miR-18a-5p targets, a dual-luciferase reporter assay was performed. Western blot analysis and immunofluorescence techniques were used to assess the protein expression levels of AKT and ERK. The rescue effects of miR-18a-5p on the proliferation or migration of VSMCs were evaluated after exposure to the AKT inhibitor MK-2206 and ERK inhibitor PD98059.

Results

The expression level of miR-18a-5p was significantly higher in the blood serum of patients with stent restenosis and in rats with carotid artery injury, and the expression of AKT and ERK was higher after carotid artery injury. The proliferation and migration abilities of VSMCs were accelerated by the overexpression of miR-18a-5p. It was found that miR-18a-5p directly modulates AKT/ERK signaling. Upregulated miR-18a-5p increased the protein expression levels of AKT and ERK and we found a positive correlation between miR-18a-5p expression level and expression of AKT and ERK. Additionally, the promoting effect of miR-18a-5p on VSMCs proliferation, migration, and invasion was reversed by ERK inhibitor or AKT inhibitor.

Conclusions

miR-18a-5p can promote proliferation of VSMCs by activating the AKT/ERK signaling pathway.

Effects of Caveolin-1-ERK1/2 pathway on endothelial cells and smooth muscle cells under shear stress

Hemodynamic forces have an important role in venous intimal hyperplasia, which is the main cause of arteriovenous fistula dysfunction. Endothelial cells (ECs) constantly exposed to the shear stress of blood flow, converted the mechanical stimuli into intracellular signals, and interacted with the underlying vascular smooth muscle cells (VSMCs). Caveolin-1 is one of the important mechanoreceptors on cytomembrane, which is related to vascular abnormalities. Extracellular signal-regulated kinase1/2 (ERK1/2) pathway is involved in the process of VSMCs proliferation and migration. In the present study, we explore the effects of Caveolin-1-ERK1/2 pathway and uremia toxins on the endothelial cells and VSMCs following shear stress application. Different shear stress was simulated with a ECs/VSMCs cocultured parallel-plate flow chamber system. Low shear stress and oscillating shear stress up-regulated the expression of fibroblast growth factor-4, platelet-derived growth factor-BB, vascular endothelial growth factor-A, ERK1/2 phosphorylation in endothelial cells, and proliferation and migration of VSMCs but down-regulated the Caveolin-1 expression in endothelial cells. Uremia toxin induces the proliferation and migration of VSMCs but not in a Caveolin-1-dependent manner in the static environment. Low shear stress-induced proliferation and migration of VSMCs is inhibited by Caveolin-1 overexpression and ERK1/2 suppression. Shear stress-regulated VSMC proliferation and migration is an endothelial cells-dependent process. Low shear stress and oscillating shear stress exert atherosclerotic influences on endothelial cells and VSMCs. Low shear stress modulated proliferation and migration of VSMCs through Caveolin-1-ERK1/2 pathway, which suggested that Caveolin-1 and ERK1/2 can be used as a new therapeutic target for the treatment of arteriovenous fistula dysfunction.

Impact statement

Venous intimal hyperplasia is the leading cause of arteriovenous fistula (AVF) dysfunction. This article reports that shear stress-regulated vascular smooth muscle cells (VSMCs) proliferation and migration is an endothelial cell (EC)-dependent process. Low shear stress (LSS) and oscillating shear stress (OSS) exert atherosclerotic influences on the ECs and VSMCs. LSS-induced proliferation and migration of VSMCs is inhibited by Caveolin-1 overexpression and extracellular signal-regulated kinase1/2 (ERK1/2) suppression, which suggested that Caveolin-1 and ERK1/2 can be used as a new therapeutic target for the treatment of AVF dysfunction.

LncRNA MRAK048635_P1 is critical for vascular smooth muscle cell function and phenotypic switching in essential hypertension

Vascular remodeling caused by essential hypertension is a leading cause of death in patients, and vascular smooth muscle cell (VSMC) dysfunction and phenotypic switching result in vascular remodeling. Therefore, inhibiting cell dysfunction and phenotypic switching in VSMCs may be a new treatment strategy for essential hypertension. The aim of the current study is to explore the roles of long non-coding RNA (lncRNA) MRAK048635_P1 in VSMC function and phenotypic switching. The MRAK048635_P1 level was determined in spontaneously hypertensive rats (SHRs) and VSMCs isolated from SHRs. MRAK048635_P1 was knocked down using a specific siRNA in VSMCs isolated from the thoracic aorta of SHRs and Wistar–Kyoto rats. Then, the proliferation and migration of VSMCs were determined using a cell counting kit-8 (CCK-8), a ³H labeling method, a transwell assay, and a wound healing assay. Flow cytometry was used to test the effect of MRAK048635_P1 on VSMC apoptosis. The protein and mRNA levels of associated genes were measured through Western blotting, immunofluorescence, and Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR). MRAK048635_P1 showed low expression during hypertension in vivo and in vitro. Down-regulation of lncRNA MRAK048635_P1 promoted proliferation and migration and inhibited apoptosis in VSMCs isolated from healthy rat vascular tissue and SHR-derived VSMCs. Importantly, we also found that down-regulation of MRAK048635_P1 could induce VSMC phenotypic switching from a contractile to a secretory phenotype. In conclusion, our findings reveal that decreased MRAK048635_P1 is probably an important factor for vascular remodeling by affecting VSMC cell function and phenotypic switching in essential hypertension.