Jitsuo Higaki

Relationship between cardio-ankle vascular index (CAVI) and carotid atherosclerosis in patients with essential hypertension

Aortic stiffness measured by aorta-iliac or carotid-femoral pulse wave velocity (PWV) predicts all-cause and cardiovascular mortality. Brachial-ankle PWV (baPWV) has been developed as a more convenient assessment of arterial stiffness. However, the problem with clinical use of baPWV is that the index itself is closely dependent on blood pressure. Recently, a new method, termed the cardio-ankle vascular index (CAVI), has been proposed in Japan to overcome the disadvantages associated with measuring PWV. However, its clinical usefulness has not yet been fully clarified. In the present study, we compared the usefulness of CAVI with that of ultrasound for evaluating atherosclerosis in patients with essential hypertension. CAVI was measured in 70 hypertensive patients. The intima-media thickness (IMT), cross-sectional distensibility coefficient (CSDC), stiffness parameter β, and mean diastolic (Vd) and systolic (Vs) flow velocities were evaluated by carotid ultrasound. The Vd/Vs ratio, an index of peripheral arterial resistance, was also calculated. CAVI was positively correlated with IMT (r=0.360, p=0.0022) and stiffness β (r=0.270, p=0.0239) and negatively correlated with Vd/Vs (r=−0.471, p<0.0001) and CSDC (r=−0.315, p=0.0079). Stepwise regression analysis revealed that age (r=0.475, p<0.0001) and pulse pressure (r=0.492, r<0.0001) were independent determinants of CAVI. These results suggest that CAVI is a useful clinical marker for evaluating atherosclerosis and arteriolosclerosis in patients with essential hypertension.

C-Reactive Protein Induces Apoptosis in Human Coronary Vascular Smooth Muscle Cells

Background—Accumulating evidence suggests that C-reactive protein (CRP), in addition to being a predictor of coronary events, may have direct actions on the vessel wall in the evolution of atherosclerosis. Although accumulation of vascular smooth muscle cells (VSMCs) in the intima is a key event in the development of arterial lesions, apoptosis of VSMCs also plays an important role in progression of atherosclerotic lesions and contributes to increased plaque vulnerability. Methods and Results—In the present study we demonstrate that CRP induces caspase-mediated apoptosis of human coronary VSMCs. DNA microarray analysis was used to identify CRP-regulated genes. The growth arrest– and DNA damage–inducible gene 153 (GADD153) mRNA expression was prominently upregulated by CRP. As confirmed by Northern blot analysis, CRP induced a time- and dose-dependent increase of GADD153 mRNA expression. GADD153, a gene involved in growth arrest and apoptosis in vascular and nonvascular cells, is regulated at both transcriptional and posttranscriptional levels. CRP regulation of GADD153 mRNA expression in VSMCs occurs primarily at the posttranscriptional level by mRNA stabilization. Small interfering RNA (siRNA) specifically targeted to GADD153 reduced CRP-induced apoptosis. GADD153 also specifically colocalized to apoptotic VSMCs in human coronary lesions, further supporting a functional role for GADD153 in CRP-induced cell death. Conclusions—These results demonstrate that GADD153 is a CRP-regulated gene in human VSMCs and plays a causal role in CRP-induced apoptosis. Pharmacological targeting of CRP expression or action may provide a novel therapy for atherosclerosis.

Clinical significance of global two-dimensional strain as a surrogate parameter of myocardial fibrosis and cardiac events in patients with hypertrophic cardiomyopathy

AIMSnLate gadolinium enhancement (LGE) on contrast-enhanced magnetic resonance imaging (MRI) in hypertrophic cardiomyopathy (HCM) has been reported to be associated with myocardial fibrosis and cardiac events. In patients with HCM, two-dimensional (2D) strain can identify subclinical global systolic dysfunction despite normal left ventricular (LV) chamber function. Therefore, this study tested the hypothesis that global 2D strain could detect subtle myocardial fibrosis and serve as a novel prognostic parameter in HCM patients.nnnMETHODS AND RESULTSnEchocardiography and MRI were performed in 48 consecutive patients with HCM and normal chamber function. We measured global longitudinal strain (GLS) in apical two-chamber, four-chamber, and long-axis views using speckle-tracking analysis. The extent of LGE (%LGE = LGE volume/total LV volume) and LV mass index were calculated by MRI using Simpsons rule and custom software. All patients were followed up for major cardiac events. Global longitudinal strain in patients with LGE was significantly lower than that without LGE (-11.8 ± 2.8 vs. -15.0 ± 1.7%, P < 0.001). Multivariate analysis showed that GLS was an independent predictor of %LGE (standard coefficient = 0.627, P < 0.001). During a mean follow-up period of 42 ± 12 months, five patients had cardiac events. When the patients were stratified based on the median level of GLS (-12.9%), all events were observed in the worse GLS group (P = 0.018).nnnCONCLUSIONnThese results suggest that global 2D strain might provide useful information on myocardial fibrosis and cardiac events in HCM patients with normal chamber function.

Hyperresistinemia Is Associated With Coexistence of Hypertension and Type 2 Diabetes

Numerous studies have demonstrated that high blood pressure substantially increases the risk of microvascular and macrovascular complications in patients with type 2 diabetes mellitus (T2DM). Currently, we found that serum resistin, an adipocyte- and monocyte-derived cytokine, was positively correlated with several components of the metabolic syndrome, including hypertension in T2DM. To investigate the association of resistin with an etiologic difference among subjects with hypertension with T2DM, hypertension without T2DM, and normotensive T2DM, we analyzed 210 subjects, including 91 with hypertension with T2DM, 55 with hypertension without T2DM, and 64 with normotensive T2DM. Serum resistin level was higher in subjects with hypertension with T2DM, followed by subjects with normotensive T2DM and hypertension without T2DM, irrespective of antihypertensive treatment status (20.9±17.6 and 14.0±8.9 versus 11.2±7.6 ng/mL, respectively; P<0.01). Simple regression analysis revealed that resistin positively correlated with blood pressure (systolic blood pressure: r=0.29, P<0.01; diastolic blood pressure: r=0.21, P<0.05) and intima-media thickness (r=0.27; P<0.05) in patients with T2DM but not in subjects with hypertension without T2DM. Multiple regression analysis, adjusted for age, gender, body mass index, fasting glucose, high-density lipoprotein cholesterol, white blood cell counts, and glomerular filtration rate, further revealed that resistin was an independent factor for high blood pressure in patients with T2DM (P<0.05). In vitro gene expression analysis in human coronary endothelial cells revealed that resistin induced fatty acid binding protein, a key molecule of insulin resistance, diabetes, and atherosclerosis. These results suggest that hyperresistinemia would contribute to the pathogenesis of hypertension in patients with T2DM, significantly linked to vascular complications and cardiovascular events.

Direct Angiotensin II Type 2 Receptor Stimulation Ameliorates Insulin Resistance in Type 2 Diabetes Mice with PPARγ Activation

Objectives The role of angiotensin II type 2 (AT2) receptor stimulation in the pathogenesis of insulin resistance is still unclear. Therefore we examined the possibility that direct AT2 receptor stimulation by compound 21 (C21) might contribute to possible insulin-sensitizing/anti-diabetic effects in type 2 diabetes (T2DM) with PPARγ activation, mainly focusing on adipose tissue. Methods T2DM mice, KK-Ay, were subjected to intraperitoneal injection of C21 and/or a PPARγ antagonist, GW9662 in drinking water for 2 weeks. Insulin resistance was evaluated by oral glucose tolerance test, insulin tolerance test, and uptake of 2-[3H] deoxy-D-glucose in white adipose tissue. Morphological changes of adipose tissues as well as adipocyte differentiation and inflammatory response were examined. Results Treatment with C21 ameliorated insulin resistance in KK-Ay mice without influencing blood pressure, at least partially through effects on the PPARγ pathway. C21 treatment increased serum adiponectin concentration and decreased TNF-α concentration; however, these effects were attenuated by PPARγ blockade by co-treatment with GW9662. Moreover, we observed that administration of C21 enhanced adipocyte differentiation and PPARγ DNA-binding activity, with a decrease in inflammation in white adipose tissue, whereas these effects of C21 were attenuated by co-treatment with GW9662. We also observed that administration of C21 restored β cell damage in diabetic pancreatic tissue. Conclusion The present study demonstrated that direct AT2 receptor stimulation by C21 accompanied with PPARγ activation ameliorated insulin resistance in T2DM mice, at least partially due to improvement of adipocyte dysfunction and protection of pancreatic β cells.

Angiotensin converting enzyme I/D polymorphism and hypertension : the Ohasama study

Objective Angiotensin-converting enzyme (ACE) I/D polymorphism in intron 16 of the ACE gene was analyzed in a general Japanese population in relation to self-blood pressure (BP) measurement at home (home BP) and ambulatory BP monitoring (ABPM) to determine the association between genetic variants of this polymorphism and hypertension. Design A cross-sectional study. Methods and results We genotyped the ACE I/D polymorphism in 1245 subjects with home BP and 803 subjects with ABPM in Ohasama, a rural community in Japan. All the subjects were 40 years of age and over, and gave written informed consent for the present genetic analysis. Hypertensive subjects were defined as those receiving antihypertensive drugs and those who had a home BP higher than 135 mmHg in systole and/or higher than 85 mmHg in diastole. The frequencies of the II, ID, and DD genotypes in these Japanese subjects were 0.45, 0.45, and 0.10, indicating a lower frequency of the D allele (0.33) than in Caucasians. There was no significant difference of BP level, prevalence of hypertension or nocturnal decline in BP among the genotypes. There were no differences in the prevalence of previous cardiovascular disease, age, body mass index, male gender, smoking, or biochemical and hormonal parameters among the three genotypes. Conclusion The present results indicate the absence of direct effects of the ACE D-allele on BP level, prevalence of hypertension, prevalence of cardiovascular disease, and circadian BP variation. We conclude there is little association between ACE I/D polymorphism and hypertension in the general Japanese population.

Osteopontin and carotid atherosclerosis in patients with essential hypertension

OPN (osteopontin), a pro-inflammatory cytokine, has recently emerged as a key factor in both vascular remodelling and the development of atherosclerosis. However, the relationship between OPN and atherosclerosis in patients without symptomatic cardiovascular disease is not clear. Therefore we measured plasma OPN levels and evaluated the correlation between plasma OPN levels and atherosclerosis as target organ damage in patients with EHT (essential hypertension). Plasma OPN levels were measured in 76 patients with EHT using a solid-phase sandwich ELISA. IMT (intima-media thickness), and V(d) and V(s) (mean diastolic and systolic flow velocities respectively) were evaluated by carotid ultrasound. The V(d)/V(s) ratio, an index of peripheral arterial resistance, was also calculated. The patients were divided on the basis of median OPN levels into a high-OPN group and a low-OPN group. The mean IMT and aldosterone levels were higher (P=0.024 and 0.031 respectively) and V(d)/V(s) was lower (P=0.007) in the high-OPN group than in the low-OPN group. Plasma OPN levels were positively correlated with mean IMT (r=0.308, P=0.0068) and negatively with V(d)/V(s) (r=-0.293, P=0.010). Stepwise regression analysis revealed that OPN was an independent determinant of mean IMT (P=0.007) and V(d)/V(s) (P=0.009), and aldosterone was an independent determinant of OPN. These results suggest that OPN plays a role in the development of atherosclerosis and may be a potential clinical marker for the prediction of atherosclerosis in patients with EHT.

Possible Role of Angiotensin-Converting Enzyme 2 and Activation of Angiotensin II Type 2 Receptor by Angiotensin-(1–7) in Improvement of Vascular Remodeling by Angiotensin II Type 1 Receptor Blockade

Cross talk between the angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II type 1 (AT1) receptor axis and the ACE2/Ang-(1–7)/Mas axis plays a role in the pathogenesis of cardiovascular remodeling. Furthermore, possible stimulation of the Ang II type 2 (AT2) receptor by Ang-(1–7) has been highlighted as a new pathway. Therefore, we examined the possibility of whether the ACE2/Ang-(1–7)/Mas axis and Ang-(1–7)/AT2 receptor axis are involved in the inhibitory effects of AT1 receptor blockers on vascular remodeling. Wild-type, Mas-knockout, and AT2 receptor knockout mice were used in this study. Vascular injury was induced by polyethylene-cuff placement around the mouse femoral artery. Some mice were treated with azilsartan, an AT1 receptor blocker, or Ang-(1–7). Neointimal formation 2 weeks after cuff placement was more marked in Mas-knockout mice compared with wild-type mice. Treatment with azilsartan or Ang-(1–7) attenuated neointimal area, vascular smooth muscle cell proliferation, increases in the mRNA levels of monocyte chemoattractant protein-1, tumor necrosis factor-&agr;, and interleukin-1&bgr;, and superoxide anion production in the injured artery; however, these inhibitory effects of azilsartan and Ang-(1–7) were less marked in Mas-knockout mice. Administration of azilsartan or Ang-(1–7) attenuated the decrease in ACE2 mRNA and increased AT2 receptor mRNA but did not affect AT1 receptor mRNA or the decrease in Mas mRNA. The inhibitory effect of Ang-(1–7) on neointimal formation was less marked in AT2 receptor knockout mice compared with wild-type mice. These results suggest that blockade of the AT1 receptor by azilsartan could enhance the activities of the ACE2/Ang-(1–7)/Mas axis and ACE2/Ang-(1–7)/AT2 receptor axis, thereby inhibiting neointimal formation.

Association between cystatin C and inflammation in patients with essential hypertension

BackgroundSerum cystatin C is not only a marker of renal function but also acts as an independent risk factor for cardiovascular damage, heart failure, and death. It is known that the initiation and progression of these cardiovascular events contributes to renal dysfunction and chronic inflammation. In this study, we investigated the relationship between cystatin C and proinflammatory cytokines.MethodsEighty-eight patients with essential hypertension participated in the study, which involved measuring proinflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and C reactive protein (CRP).ResultsPositive correlations were detected between cystatin C and estimated glomerular filtration rate (eGFR) (rxa0=xa0−0.503, pxa0<xa00.001), systolic blood pressure (rxa0=xa0−0.246, pxa0=xa00.034), and pulse pressure (rxa0=xa0−0.295, pxa0=xa00.010). In contrast, serum creatinine correlated only with eGFR (rxa0=xa0−0.755, pxa0<xa00.001) and eGFR correlated only with age (rxa0=xa0−0.339, pxa0=xa00.001) and not with the other clinical parameters, whereas cystatin C also correlated with log natural (ln) IL-6 (rxa0=xa0−0.247, pxa0=xa00.033) and ln TNF-α (rxa0=xa0−0.405, pxa0<xa00.001) but not with CRP (rxa0=xa0−0.188, pxa0=xa00.108). In contrast, plasma creatinine and eGFR did not correlate with any of these proinflammatory cytokines. Stepwise regression analysis showed that ln TNF-α, eGFR and pulse pressure were independent determinants of serum cystatin C concentration.ConclusionThis study showed that cystatin C is a marker of inflammation as well as renal function.

Osteopontin deficiency protects against aldosterone-induced inflammation, oxidative stress, and interstitial fibrosis in the kidney

Osteopontin (OPN) has been implicated in the pathology of several renal conditions. Recently, we demonstrated in vitro that aldosterone has important roles in collagen synthesis by inducing OPN (Irita J, Okura T, Kurata M, Miyoshi K, Fukuoka T, Higaki J. Hypertension 51: 507-513, 2008). The aim of the present study was to clarify the roles of OPN in aldosterone-mediated renal fibrosis by infusing aldosterone into either wild-type (WT) or OPN knockout mice (OPN(-/-)). We used uninephrectomized mice treated with aldosterone and high salt to exacerbate renal fibrosis. After 4 wk of treatment with aldosterone, we showed similar increases in systolic blood pressure in both strains of mice. Urine albumin excretion was greater in aldosterone-infused WT mice than in aldosterone-infused OPN(-/-) mice. Immunohistochemical analysis showed high levels of OPN expression in aldosterone-infused WT mice. Interstitial fibrosis and inflammatory infiltrations were increased in aldosterone-infused WT mice compared with either vehicle-infused WT or aldosterone-infused OPN(-/-) mice. These changes were ameliorated markedly by eplerenone treatment in aldosterone-infused WT mice. Aldosterone-infused WT mice also had increased expression of NADPH oxidase subunits compared with aldosterone-infused OPN(-/-) mice. We observed a marked increase in oxidative stress markers in aldosterone-infused WT mice compared with aldosterone-infused OPN(-/-) mice. These results indicate that OPN is a promoter of aldosterone-induced inflammation, oxidative stress, and interstitial fibrosis in the kidney and suggest that inhibition of OPN may be a potential therapeutic target for prevention of renal injury.