AT1 receptors modulate ethanol-induced loss of anticontractile effect of perivascular adipose tissue

Ethanol consumption activates renin-angiotensin-aldosterone system (RAAS), which plays a major role in the pro-contractile and hypertensive effects linked to ethanol. We hypothesized that ethanol consumption induces loss of the anticontractile effect of perivascular adipose tissue (PVAT)through RAAS-mediated mechanisms. We examined the contribution of angiotensin II type 1 receptors (AT1R) to ethanol-induced PVAT dysfunction. With this purpose, male Wistar Hannover rats were treated with ethanol 20 % (in volume ratio) and/or losartan (antagonist of AT1R; 10 mg/kg/day, gavage) for 9 weeks. Losartan prevented the increase in blood pressure and the loss of the anticontractile effect of PVAT induced by ethanol consumption. PVAT dysfunction occurred after 3 and 9 weeks of treatment with ethanol in an endothelium-dependent manner. Blockade of AT1R prevented ethanol-induced reduction of adiponectin levels in PVAT from ethanol-treated rats. Functional assays revealed that ethanol impaired the anticontractile effect of PVAT-derived angiotensin (1-7) and endothelial nitric oxide (NO). In conclusion, AT1R are implicated in ethanol-induced loss of the anticontractile effect of PVAT. In PVAT, AT1R activation decreases the production of adiponectin, a PVAT-derived factor that promotes vasorelaxation in an endothelium-dependent manner. In the endothelium, AT1R favors the production of superoxide (O2•-) leading to a reduction in NO bioavailability. These responses impair the vasodilator action induced by PVAT-derived angiotensin (1-7), which occurs via Mas receptors located in endothelial cells. Ethanol-induced PVAT dysfunction favors vascular hypercontractility, a response that could contribute to the hypertensive state associated with ethanol consumption.

Genetics of Cholesterol-Related Genes in Metabolic Syndrome: A Review of Current Evidence

Metabolic syndrome (MetS) refers to a cluster of metabolic dysregulations, which include insulin resistance, obesity, atherogenic dyslipidemia and hypertension. The complex pathogenesis of MetS encompasses the interplay between environmental and genetic factors. Environmental factors such as excessive nutrients and sedentary lifestyle are modifiable and could be improved by lifestyle modification. However, genetic susceptibility to MetS, a non-modifiable factor, has attracted the attention of researchers, which could act as the basis for future diagnosis, prognosis, and therapy for MetS. Several cholesterol-related genes associated with each characteristic of MetS have been identified, such as apolipoprotein, lipoprotein lipase (LPL), cholesteryl ester transfer protein (CETP) and adiponectin. This review aims to summarize the genetic information of cholesterol-related genes in MetS, which may potentially serve as biomarkers for early prevention and management of MetS.

Brachial-ankle pulse wave velocity, cardio-ankle vascular index, and prognosis

Background

Brachial–ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI) are indices of arterial stiffness, and several studies have used these indices. However, there is no comprehensive review of these parameters in the prognostic significance.

Methods

The aim of this study was to review the articles exploring the prognostic significance of these parameters. Articles demonstrating independent significance after multivariate analysis on the Cox proportional hazards model were defined as “successful.” The success rate was compared using Fisher’s exact test. In addition, multivariate logistic regression analysis was performed to explore the independent determinants of the success of prognostic prediction.

Results

The success rate of the baPWV articles (65.7% [46/70]) tended to be higher than that of the CAVI articles (40.0% [6/15]; P=0.083). Multivariate analysis demonstrated that log (number of patients) (OR 11.20, 95% CI 2.45–51.70, P=0.002) and dialysis population (OR 0.28, 95% CI 0.08–0.94, P=0.039) were positive and negative independent determinants of the success of prognostic prediction, respectively. In addition, after redefining two studies as the absence of arteriosclerosis obliterans (ASO) exclusion, baPWV (OR 3.36, 95% CI 0.86–13.20, P=0.083) and the existence of exclusion criteria of ASO (OR 3.08, 95% CI 0.96–9.93, P=0.060) exhibited statistical tendency in the multivariate analysis.

Conclusion

This study demonstrated that the number of study participants and dialysis population were the independent determinants of the success of prognostic prediction. This study also showed the importance of exclusion criteria of ASO when using these indices. In addition, a prospective large-scale study to confirm the superiority in the prognostic prediction of these indices is warranted.

Adiponectin enhances biological functions of vascular endothelial progenitor cells through the mTOR-STAT3 signaling pathway

Adiponectin (APN), an adipose tissue-excreted adipokine, plays protective roles in metabolic and cardiovascular diseases. In this study, the effects and mechanisms of APN on biological functions of rat vascular endothelial progenitor cells (VEPCs) were investigated in vitro. After administrating APN in rat VEPCs, the proliferation was measured by methyl thiazolyl tetrazolium (MTT) method, the apoptotic rate was test by Flow cytometry assay, mRNA expression of B-cell lymphoma-2 (Bcl-2) and vascular endothelial growth factor (VEGF) was determined by real-time reverse transcriptase polymerase chain reaction (RT-PCR), and protein expression of mechanistic target of rapamycin (mTOR), signal transducer and activator of transcription 3 (STAT3) and phospho-STAT3 (pSTAT3) was analyzed by Western blot. It was suggested that APN promoted the optical density (OD) value of VEPCs, enhanced mRNA expression of Bcl-2 and VEGF, and inhibited cell apoptotic rate. Furthermore, protein expression of pSTAT3 was also increased in the presence of APN. Moreover, APN changed-proliferation, apoptosis and VEGF expression of VEPCs were partially suppressed after blocking the mTOR-STAT3 signaling pathway by the mTOR inhibitor XL388. It was indicated that APN promoted biological functions of VEPCs through targeting the mTOR-STAT3 signaling pathway.

T allele at ADIPOQ rs1501299 G/T polymorphism is more susceptible to the influence of circulating adiponectin on arterial stiffness in nondiabetic men

BACKGROUND

Low adiponectin levels are associated with increased insulin resistance (IR) and arterial stiffness in hypertensive patients, but higher adiponectin levels are also found in heart failure patients. This discrepancy has not been fully resolved, but it may be related to the adiponectin gene (ADIPOQ) which regulates adiponectin production. We aimed to investigate whether the relationship between adiponectin and arterial stiffness is associated with ADIPOQ rs1501299 G/T polymorphism in nondiabetic Korean men.

METHODS

In nondiabetic men without disease (n = 301), anthropometric parameters, lipid profiles, IR, circulating adiponectin, and brachial-ankle pulse wave velocity (baPWV) were measured. rs1501299 G/T polymorphism was also analyzed.

RESULTS

Circulating adiponectin levels were negatively correlated with baPWV and homeostatic model assessment-IR in the T allele carriers (n = 167), but this correlation was not observed in the GG subjects (n = 134). However, a positive correlation between baPWV and IR was observed in the GG subjects, but not in the T carriers. These patterns were maintained after the adjustment for confounding factors. A stepwise linear regression analysis revealed that circulating adiponectin and systolic blood pressure (BP) were the main influencing factors on baPWV levels in T carriers, but systolic BP, IR and age were the main contributors to increased baPWV levels in the GG subjects.

CONCLUSIONS

This study demonstrates that the relationship between circulating adiponectin and arterial stiffness is different according to ADIPOQ rs1501299 G/T polymorphism, and suggests that T allele is more susceptible to the influence of adiponectin on arterial stiffness than GG homozygotes. This information may prove to be useful for personal-based early prevention and management of atherosclerotic risk.

Translating the biology of adipokines in atherosclerosis and cardiovascular diseases: Gaps and open questions

AIM

Critically discuss the available data, to identify the current gaps and to provide key concepts that will help clinicians in translating the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

DATA SYNTHESIS

Adipose tissue is nowadays recognized as an active endocrine organ, a function related to the ability to secrete adipokines (such as leptin and adiponectin) and pro-inflammatory cytokines (tumor necrosis factor alpha and resistin). Studies in vitro and in animal models have observed that obesity status presents a chronic low-grade inflammation as the consequence of the immune cells infiltrating the adipose tissue as well as adipocytes. This inflammatory signature is often related to the presence of cardiovascular diseases, including atherosclerosis and thrombosis. These links are less clear in humans, where the role of adipokines as prognostic marker and/or player in cardiovascular diseases is not as clear as that observed in experimental models. Moreover, plasma adipokine levels might reflect a condition of adipokine-resistance in which adipokine redundancy occurs. The investigation of the cardio-metabolic phenotype of carriers of single nucleotide polymorphisms affecting the levels or function of a specific adipokine might help determine their relevance in humans. Thus, the aim of the present review is to critically discuss the available data, identify the current gaps and provide key concepts that will help clinicians translate the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

Single nucleotide polymorphism of adiponectin +276 G/T is associated with the susceptibility to essential hypertension in a Turkish population

BACKGROUND

It is well known that arterial stiffness is associated with hypertension. Recent studies have shown that adiponectin +276 G/T, ACE I/D, AGTR1 A1166C, and eNOS E298D polymorphisms are likely to be risk factors for arterial stiffness. In this study, we aimed to investigate possible associations between these single-nucleotide polymorphisms (SNPs) and essential hypertension in a Turkish population.

METHODS

The study population consisted of 170 patients who were diagnosed with essential hypertension and 170 sex- and age-matched controls. Genotyping of adiponectin +276 G/T, ACE I/D, AGTR1 A1166C, and eNOS E298D SNPs were performed using real-time polymerase chain reaction and commercially produced kits.

RESULTS

The percentage of the adiponectin +276 T allele carriers was significantly higher in the patients with hypertension (33%) than in the controls (25%, p < 0.011). Through multiple logistic regression analysis, the adiponectin +276 T allele carrier was found to be associated with an increased risk of hypertension (TT vs. GG and TG: odds ratio = 3.318, p = 0.014, 95% confidence interval: 1.269-8.678). The genotype distributions or allelic frequencies of ACE I/D, AGTR1 A1166C, and eNOS E298D SNPs did not significantly differ between the patients with hypertension and the controls.

CONCLUSION

The present study demonstrated that the adiponectin +276 G/T SNP is likely to be a risk factor for essential hypertension in a Turkish population.

Adiponectin Attenuates Angiotensin II-Induced Vascular Smooth Muscle Cell Remodeling through Nitric Oxide and the RhoA/ROCK Pathway

INTRODUCTION

Adiponectin (APN), an adipocytokine, exerts protective effects on cardiac remodeling, while angiotensin II (Ang II) induces hypertension and vascular remodeling. The potential protective role of APN on the vasculature during hypertension has not been fully elucidated yet. Here, we evaluate the molecular mechanisms of the protective role of APN in the physiological response of the vascular wall to Ang II.

METHODS AND RESULTS

Rat aortic tissues were used to investigate the effect of APN on Ang II-induced vascular remodeling and hypertrophy. We investigated whether nitric oxide (NO), the RhoA/ROCK pathway, actin cytoskeleton remodeling, and reactive oxygen species (ROS) mediate the anti-hypertrophic effect of APN. Ang II-induced protein synthesis was attenuated by pre-treatment with APN, NO donor S-nitroso-N-acetylpenicillamine (SNAP), or cGMP. The hypertrophic response to Ang II was associated with a significant increase in RhoA activation and vascular force production, which were prevented by APN and SNAP. NO was also associated with inhibition of Ang II-induced phosphorylation of cofilin. In addition, immunohistochemistry revealed that 24 h Ang II treatment increased the F- to G-actin ratio, an effect that was inhibited by SNAP. Ang II-induced ROS formation and upregulation of p22(phox) mRNA expression were inhibited by APN and NO. Both compounds failed to inhibit Nox1 and p47(phox) expression.

CONCLUSION

Our results suggest that the anti-hypertrophic effects of APN are due, in part, to NO-dependent inhibition of the RhoA/ROCK pathway and ROS formation.

Serum adiponectin is a negative predictor of central arterial stiffness in kidney transplant patients

BACKGROUND

The role of adiponectin in arterial stiffness and its relationship to cardiovascular disease is not fully demonstrated and needs further elaboration. In this study, the association between adiponectin level and arterial stiffness is studied among kidney transplant patients.

MATERIAL AND METHODS

Anthropometric data and biochemical data including fasting glucose, lipid profile, renal function and serum adiponectin were determined in 55 kidney transplant patients. Central arterial stiffness was measured and presented by carotid-femoral pulse wave velocity.

RESULTS

Univariate linear analysis showed that body weight, waist circumference, brachial pulse pressure and body mass index were correlated positively with carotid-femoral pulse wave velocity in this patient group. However, logarithmically transformed adiponectin level (log-adiponectin) correlated negatively with carotid-femoral pulse wave velocity. In multivariate regression analysis of factors significantly associated with carotid-femoral pulse wave velocity, it showed that both log-adiponectin (β = -0.427; R(2) = 0.205, p = 0.001) and body weight (β = 0.327; R(2 )=( )0.106, p = 0.007) were independently predictive of central arterial stiffness.

CONCLUSION

Our study suggests that fasting serum adiponectin is negatively associated with carotid-femoral pulse wave velocity, hence arterial stiffness, in kidney transplant patients.

ADIPOQ single nucleotide polymorphism: Association with adiponectin and lipoproteins levels restricted to men

Adiponectin is an adipokine inversely correlated with obesity, which has beneficial effect on insulin resistance and lipid metabolism. Considering its potential as a therapeutic target in the metabolic disorder contexts, and in order to add knowledge in the area, our study evaluated the ADIPOQ 276G > T polymorphism effect on adiponectin levels, and on lipoproteins of clinical interest in a population sample composed of 211 healthy individuals. Significant effects were observed only among men: the carriers of heterozygous genotype (GT) showed high levels of adiponectin (p = 0.018), while the rare homozygous genotype (TT) gave its carriers a negative phenotype, represented by higher levels of low density lipoprotein cholesterol (LDL-C) (p = 0.004 and p = 0.005) and total cholesterol (TC) (p = 0.010 and p = 0.005) compared to carriers of other genotypes (GG and GT respectively), the independent effect of SNP on LDL-C and TC levels was confirmed by multiple regression analysis (p = 0.008 and p = 0.044). We found no evidence of correlation between circulating adiponectin levels and biochemical markers, which suggests, therefore, an SNP 276G > T independent effect on adiponectin levels and on lipoprotein metabolism in men enrolled in this study.

Adiponectin Genotype, Blood Pressures, and Arterial Stiffness: The Cardiometabolic Risk in Chinese (CRC) Study

The authors examined whether the adiponectin gene (ADIPOQ) variant was associated with blood pressure and arterial stiffness in Chinese adults. A genome-wide association study of the adiponectin variant rs864265 in the ADIPOQ gene was genotyped in a total of 2364 participants. After adjustment for sex, age, body mass index (BMI), fasting glucose, and lipids, participants carrying the T allele of rs864265 showed a greater increase in carotid-femoral pulse wave velocity (cfPWV) and systolic blood pressure (SBP). Further adjustment for blood pressure did not appreciably change the association with cfPWV. The authors found significant interactions between rs864265 and BMI, waist circumference, body fat percentage, and SBP in relation to cfPWV (P for interaction = .035, .001, .003, .013, respectively). The T allele of rs864265 was associated with high blood pressure and arterial stiffness. BMI, body fat percentage, waist circumference, and SBP might modify the effects of genetic polymorphism on arterial stiffness.

Different Impacts of Cardiovascular Risk Factors on Arterial Stiffness versus Arterial Wall Thickness in Japanese Patients with Type 2 Diabetes Mellitus

AIM

We statistically investigated whether the impact of cardiovascular risk factors on arterial stiffness would be different from that on arterial wall thickness.

METHODS

We analyzed 1648 Japanese type 2 diabetic patients. Arterial stiffness was evaluated by pulse wave verbosity (PWV) and wall thickness was assessed with carotid intima-media thickness (IMT) by ultrasonography. We developed a common regression model to PWV and IMT by extending the linear mixed model and statistically detected the difference in the impact of cardiovascular risk factors between the two indices.

RESULTS

There was a significant correlation between PWV and IMT (r=0.365, p ＜ 0.001). Sex, diabetic duration, hemoglobin A1c levels, and the presence of retinopathy and cardiovascular disease were comparable independent risk factors for elevated PWV and IMT. On the other hand, the impact of age, systolic blood pressure, and low- and high-density lipoprotein cholesterol levels were significantly different between the two measurements (all p ＜ 0.05). Cholesterol levels were significantly associated with IMT but not with PWV. Age and systolic blood pressure had a significant impact on both measurements, but the impact on PWV was significantly greater than that on IMT. Indeed, patients with low IMT but with advanced age and high systolic pressure had high PWV, whereas patients with low PWV but with impaired cholesterol levels had high IMT.

CONCLUSION

The extended linear mixed model statistically confirmed that the impact of cardiovascular risk factors on elevated PWV and IMT were not identical in Japanese patients with type 2 diabetes mellitus.

Genetic determinants of arterial stiffness

Stiffness of large arteries (called arteriosclerosis) is an independent predictor of cardiovascular morbidity and mortality. Although previous studies have shown that arterial stiffness is moderately heritable, genetic factors contributing to arterial stiffness are largely unknown. In this paper, we reviewed the available literature on genetic variants that are potentially related to arterial stiffness. Most variants have shown mixed depictions of their association with arterial stiffness across multiple studies. Various methods to measure arterial stiffness at different arterial sites can contribute to these inconsistent results. In addition, studies in patient populations with hypertension or atherosclerosis may overestimate the impact of genetic variants on arterial stiffness. Future studies are recommended to standardize current measures of arterial stiffness in different age groups. Studies conducted in normal healthy subjects may also provide better opportunities to find novel genetic variants of arterial stiffness.

Adiponectin levels and the risk of hypertension: a systematic review and meta-analysis

Animal studies and small controlled studies in humans suggest that adiponectin may regulate blood pressure via brain-mediated and endothelium-mediated mechanisms. We performed a systematic review and meta-analysis to evaluate the epidemiological evidence on plasma adiponectin levels and hypertension in free-living adult population. A systematic search of MEDLINE and EMBASE, up to February 2013, identified 43 nonprospective and 5 prospective studies that included 17 598 adults (8220 with hypertension; mean age 19-69 years; and mean body mass index 22-38 kg/m(2)). Two investigators independently extracted data on adiponectin levels by hypertension status and dose-response relationship. We used a random-effects model to compute the weighted mean difference in adiponectin levels between adults with hypertension and normotensive adults and a 2-stage generalized least-square trend methods to compute the odds ratio of hypertension per 1 µg/mL increase in adiponectin. Adults with hypertension had 1.64 µg/mL (95% confidence interval, -2.07, -1.21) lower adiponectin levels than normotensive adults. Every 1 µg/mL increase in adiponectin levels was associated with 6% reduced risk of hypertension (95% confidence interval, 0.92, 0.97). These findings were consistent across study design and characteristics, including age, sex, and body mass index (P>0.05). However, our meta-analysis was limited by unexplained large between-study heterogeneity, a small number of prospective studies, and selective reporting of dose-response data. In conclusion, epidemiological evidence suggests that plasma adiponectin level is a biomarker and possible mediator in the development of adiposity-related hypertension. The question remains as to adiponectin as a potential therapeutic target and its relationship with other adipokines in blood pressure regulation.