Rho-associated kinase activity, endothelial function, and cardiovascular risk factors

Hyperuricemia is independently associated with endothelial dysfunction in postmenopausal women but not in premenopausal women

OBJECTIVES

The purpose of this study was to determine the relationships between uric acid, endothelial function and cardiovascular risk factors and to investigate whether menopausal status was associated with the relationship between uric acid and endothelial function in women.

DESIGN

Cross-sectional study.

SETTING

3 general hospitals in Japan.

PARTICIPANTS

749 Japanese women aged 30-74 years recruited from people who underwent health-screening examinations with agreement for measurement of vascular function.

MEASURES

We measured serum concentrations of uric acid and flow-mediated vasodilation (FMD). Percentage of FMD (peak diameter-baseline diameter/baseline diameter) was used for analysis. Endothelial dysfunction was defined as FMD ≤4.90%, division point for the lowest tertile and the middle tertile of FMD. Menopause women were defined as participants without menstruation for over 1 year or participants with a history of hysterectomy or bilateral oophorectomy.

RESULTS

Of the 749 participants, 368 (49.1%) were premenopausal women and 381 (50.9%) were postmenopausal women. Age, body mass index, systolic blood pressure, total cholesterol, triglycerides, glucose, estimated glomerular filtration rate and Framingham risk score were significantly correlated with serum uric acid level. FMD showed a gradual decrease in accordance with the serum uric acid level in the entire study population (<4 mg/dL, 6.85±3.65%; 4 to <5 mg/dL, 6.79±3.60%; 5 to <6 mg/dL, 6.24±3.58%; ≥6 mg/dL, 5.27±3.18%; p=0.01). Multivariate analysis revealed that uric acid was a significantly independent risk factor for endothelial dysfunction in postmenopausal women (OR 1.23, 95% CI 1.01 to 1.50), but not in premenopausal women.

CONCLUSIONS

These findings suggest that uric acid can be used as a risk marker of endothelial dysfunction in a female population, and particularly as an independent risk factor in postmenopausal women but not in premenopausal women.

REGISTRATION NUMBER OF THE STUDY

UMIN000003409.

Relationship between flow-mediated vasodilation and cardiovascular risk factors in a large community-based study

Objective

To determine the relationships between flow-mediated vasodilation (FMD) and cardiovascular risk factors, and to evaluate confounding factors for measurement of FMD in a large general population in Japan.

Methods

This was a cross-sectional study. A total of 5314 Japanese adults recruited from people who underwent health screening from 1 April 2010 to 31 August 2012 at 3 general hospitals in Japan. Patients’ risk factors (age, Body Mass Index, blood pressure, cholesterol parameters, glucose level and HbA1c level) and prevalence of cardiovascular disease (coronary heart disease and cerebrovascular disease) were investigated.

Results

Univariate regression analysis revealed that FMD correlated with age (r=−0.27, p<0.001), Body Mass Index (r=−0.14, p<0.001), systolic blood pressure (r=−0.18, p<0.001), diastolic blood pressure (r=−0.13, p<0.001), total cholesterol (r=−0.07, p<0.001), triglycerides (r=−0.10, p<0.001), high-density lipoprotein cholesterol (r=0.06, p<0.001), low-density lipoprotein cholesterol (r=−0.04, p=0.01), glucose level (r=−0.14, p<0.001), HbA1c (r=−0.14, p<0.001), and baseline brachial artery diameter (r=−0.43, p<0.001) as well as Framingham Risk score (r=−0.29, p<0.001). Multivariate analysis revealed that age (t value=−9.17, p<0.001), sex (t value=9.29, p<0.001), Body Mass Index (t value=4.27, p<0.001), systolic blood pressure (t value=−2.86, p=0.004), diabetes mellitus (t value=−4.19, p<0.001), smoking (t value=−2.56, p=0.01), and baseline brachial artery diameter (t value=−29.4, p<0.001) were independent predictors of FMD.

Conclusions

FMD may be a marker of the grade of atherosclerosis and may be used as a surrogate marker of cardiovascular outcomes. Age, sex, Body Mass Index, systolic blood pressure, diabetes mellitus, smoking and, particularly, baseline brachial artery diameter are potential confounding factors in the measurement of FMD.

Crucial role of ROCK2 in vascular smooth muscle cells for hypoxia-induced pulmonary hypertension in mice

OBJECTIVE

Rho/Rho-kinase (ROCK) pathway in vascular smooth muscle cells (VSMCs) plays an important role in the pathogenesis of cardiovascular diseases, including pulmonary arterial hypertension (PAH). Rho-kinase has 2 isoforms, ROCK1 and ROCK2, with different functions in different cells; ROCK1 for circulating inflammatory cells and ROCK2 for the vasculature. In the present study, we aimed to examine whether ROCK2 in VSMC is involved in the pathogenesis of PAH.

APPROACH AND RESULTS

In patients with PAH, the expression of ROCK2 was increased in pulmonary arterial media and primary pulmonary arterial smooth muscle cells when compared with controls. To investigate the role of ROCK2 in VSMC, we generated VSMC-specific heterozygous ROCK2-deficient (ROCK2(+/-)) mice and VSMC-specific ROCK2-overexpressing transgenic (ROCK2-Tg) mice. The extent of hypoxia-induced pulmonary hypertension was reduced in ROCK2(+/-) mice and was enhanced in ROCK2-Tg mice compared with respective littermates. The protein expression of ROCK activity and phosphorylated extracellular signal-regulated kinase and the number of Ki67-positive proliferating cells in the lung were reduced in ROCK2(+/-) mice and were increased in ROCK2-Tg mice compared with respective littermates. In cultured mouse aortic VSMC, migration and proliferation activities were reduced in ROCK2(+/-) mice, and migration activity was increased in ROCK2-Tg mice compared with respective littermates. In addition, in primary pulmonary arterial smooth muscle cells from a patient with PAH, ROCK2 was required for migration and proliferation through ROCK and extracellular signal-regulated kinase activation.

CONCLUSIONS

ROCK2 in VSMC contributes to the pathogenesis of PAH.

A novel noninvasive and simple method for assessment of endothelial function: enclosed zone flow-mediated vasodilation (ezFMD) using an oscillation amplitude measurement

BACKGROUND

It is clinically important to estimate the degree of endothelial dysfunction. Several methods have been used to assess endothelial function in humans. Recently, we developed a new noninvasive method for measurement of vascular response to reactive hyperemia in the brachial artery, named enclosed zone flow-mediated vasodilation (ezFMD). The purpose of this study was to determine the validity of ezFMD for assessment of endothelial function.

METHODS AND RESULTS

We measured ezFMD by a new device using an oscillometric method and conventional FMD using ultrasonography in 306 subjects, including patients with hypertension, dyslipidemia, and diabetes mellitus (218 men and 88 women, 30 ± 16 yr). Univariate regression analysis revealed that ezFMD significantly correlated with age (r = -0.42, P < 0.0001), body mass index (r = -0.13, P = 0.028), systolic blood pressure (r = -0.15, P = 0.009), diastolic blood pressure (r = -0.14, P = 0.011), fasting glucose level (r = -0.27, P = 0.006), smoking (r = -0.21, P = 0.007) and baseline pulse wave amplitude (r = -0.51, P < 0.0001). ezFMD significantly correlated with conventional FMD (r = 0.34, P < 0.0001). Multiple regression analysis revealed that age (P = 0.002), body mass index (P = 0.013), systolic blood pressure (P = 0.009), smoking (P = 0.004) and baseline pulse wave amplitude (P < 0.001) were independent predictors of ezFMD.

CONCLUSIONS

These findings suggest that measurement of ezFMD, a novel noninvasive and simple method, may be useful for determination of vascular diameter response to reactive hyperemia. Since ezFMD is automatically measured by a device with an oscillometric method, measurement of ezFMD is easier and less biased than that of conventional FMD.

Nitroglycerine-Induced Vasodilation for Assessment of Vascular Function

Objective—

Nitroglycerine-induced vasodilation has been used as a control test for flow-mediated vasodilation (FMD) to differentiate endothelium-dependent from endothelium-independent response when evaluating endothelial function in humans. Recently, nitroglycerine-induced vasodilation has also been reported to be impaired in patients with atherosclerosis. The purpose of this study was to determine the relationships between nitroglycerine-induced vasodilation and cardiovascular risk factors.

Approach and Results—

We measured nitroglycerine-induced vasodilation and FMD in 436 subjects who underwent health examinations (mean age, 53±19 years; age range, 19–86 years), including patients with cardiovascular diseases. There was a significant relationship between nitroglycerine-induced vasodilation and FMD ( r =0.42; P <0.001). Univariate regression analysis revealed that nitroglycerine-induced vasodilation correlated with age ( r =−0.34; P <0.001), systolic blood pressure ( r =−0.32; P <0.001), diastolic blood pressure ( r =−0.24; P <0.001), heart rate ( r =−0.21; P <0.001), glucose ( r =−0.23; P <0.001), and smoking pack-year ( r =−0.12; P =0.01), as well as Framingham risk score ( r =−0.30; P <0.001). Nitroglycerine-induced vasodilation was significantly smaller in patients with cardiovascular disease than in both subjects with and without cardiovascular risk factors (10.5±5.6% versus 13.7±5.4% and 15.3±4.3%; P <0.001, respectively), whereas there was no significant difference in nitroglycerine-induced vasodilation between subjects with and without cardiovascular risk factors. Multivariate analysis revealed that male sex, body mass index, hypertension, diabetes mellitus, baseline brachial artery diameter, and FMD were independent predictors of nitroglycerine-induced vasodilation.

Conclusions—

These findings suggest that nitroglycerine-induced vasodilation may be a marker of the grade of atherosclerosis. FMD should be interpreted as an index of vascular function reflecting both endothelium-dependent vasodilation and endothelium-independent vasodilation in subjects with impaired nitroglycerine-induced vasodilation.

Rho-kinase inhibition improves vasodilator responsiveness during hyperinsulinemia in the metabolic syndrome

In patients with the metabolic syndrome (MetS), the facilitatory effect of insulin on forearm vasodilator responsiveness to different stimuli is impaired. Whether the RhoA/Rho kinase (ROCK) pathway is involved in this abnormality is unknown. We tested the hypotheses that, in MetS patients, ROCK inhibition with fasudil restores insulin-stimulated vasodilator reactivity and that oxidative stress plays a role in this mechanism. Endothelium-dependent and -independent forearm blood flow responses to acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, were assessed in MetS patients (n = 8) and healthy controls (n = 5) before and after the addition of fasudil (200 μg/min) to an intra-arterial infusion of insulin (0.1 mU/kg/min). In MetS patients (n = 5), fasudil was also infused without hyperinsulinemia. The possible involvement of oxidative stress in the effect of fasudil during hyperinsulinemia was investigated in MetS patients (n = 5) by infusing vitamin C (25 mg/min). In MetS patients, compared with saline, fasudil enhanced endothelium-dependent and -independent vasodilator responses during insulin infusion (P < 0.001 and P = 0.008, respectively), but not in the absence of hyperinsulinemia (P = 0.25 and P = 0.13, respectively). By contrast, fasudil did not affect vasoreactivity to ACh and SNP during hyperinsulinemia in controls (P = 0.11 and P = 0.56, respectively). In MetS patients, fasudil added to insulin and vitamin C did not further enhance vasodilation to ACh and SNP (P = 0.15 and P = 0.43, respectively). In the forearm circulation of patients with the MetS, ROCK inhibition by fasudil improves endothelium-dependent and -independent vasodilator responsiveness during hyperinsulinemia; increased oxidative stress seems to be involved in the pathophysiology of this phenomenon.

Endothelial dysfunction and hypertension in aging

Hypertension is one of the common diseases in the elderly. The prevalence of hypertension markedly increases with advancing age. Both aging and hypertension have a critical role in cardiovascular and cerebrovascular complications. Although aging and hypertension, either independently or collectively, impair endothelial function, aging and hypertension may have similar cascades for the pathogenesis and development of endothelial dysfunction. Nitric oxide (NO) has an important role in regulation of vascular tone. Decrease in NO bioavailability by endothelial dysfunction would lead to elevation of blood pressure. An imbalance of reduced production of NO or increased production of reactive oxygen species, mainly superoxide, may promote endothelial dysfunction. One possible mechanism by which the prevalence of hypertension is increased in relation to aging may be advancing endothelial dysfunction associated with aging through an increase in oxidative stress. In addition, endothelial cell senescence is also involved in aging-related endothelial dysfunction. In this review, we focus on recent findings and interactions between endothelial function, oxidative stress and hypertension in aging.

Striking crosstalk of ROCK signaling with endothelial function

Rho-associated coiled-coil forming protein kinases (ROCKs), the downstream target proteins of RhoA, are ubiquitously expressed serine-threonine protein kinases. ROCKs have diverse cellular functions, e.g. smooth muscle contraction, actin cytoskeleton organization, cell adhesion, and gene expression. Accumulating evidence has revealed that ROCKs are substantially involved in cardiovascular disorders such as angina, cerebral ischemia, myocardial ischemia, and cardiac hypertrophy. So far, the significant relationship of ROCKs with endothelial function has been reported. ROCKs inhibition by statins or other selective inhibitors leads to the upregulation and activation of endothelial nitric oxide synthase, resulting in the reduction of vascular inflammation and atherosclerosis. Meanwhile, it has been also demonstrated that endogenous nitric oxide could inhibit RhoA/ROCK signaling pathway. Taken together, there might be critical crosstalk of ROCKs with endothelial function. In addition, we further focus on leukocyte ROCK activity as a surrogate marker in patients with atherosclerosis-related diseases. Indeed, leukocyte ROCK activity has been shown to be increased in atherosclerotic patients, indicating the possible usage of leukocyte ROCK activity as a surrogate marker similar to endothelial function evaluated by flow-mediated dilation. Here, we review concerning ROCK signaling pathway, especially focusing on the crosstalk of ROCKs with endothelial function.