Mie Kurata

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.

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.

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.

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.

Valsartan reduces serum cystatin C and the renal vascular resistance in patients with essential hypertension.

A high level of albuminuria and increased renal vascular resistance are associated with hypertensive renal damage. In this study, the authors investigated the effect of the angiotensin II receptor blocker, valsartan, on renal function and intrarenal hemodynamics in non-diabetic patients with essential hypertension. A prospective three-month study of the effects of valsartan, 40–80 mg/day, was performed in 30 hypertensive patients. As an assessment of renal function, serum creatinine, urine albumin/creatinine (Alb/Cr) ratio, and serum cystatin C levels were evaluated. Doppler ultrasonography of the kidney was performed for the evaluation of renal hemodynamics. Peak-systolic, end-diastolic, and mean velocities of interlobar arteries were evaluated, and the pulsatility index (PI) and resistive index (RI) were calculated. It was determined that patients with microalbuminuria had higher levels of serum cystatin C, PI, and RI compared to patients without microalbuminuria. Valsartan treatment significantly reduced systolic and diastolic blood pressure and decreased the Alb/Cr ratio. Serum creatinine was not changed, whereas serum cystatin C levels were significantly reduced. Valsartan treatment significantly decreased the PI in all patients and both PI and RI in patients with microalbuminuria. These results suggest that the angiotensin II receptor blocker, valsartan, is able to improve renal function by reducing renal vascular resistance in hypertensive patients, especially in patients with microalbuminuria, and may prevent future renal failure in patients with essential hypertension.

Osteopontin in Rat Renal Fibroblasts: Functional Properties and Transcriptional Regulation by Aldosterone

Osteopontin (OPN), a proinflammatory cytokine, plays an important role in renal fibrosis. We reported that plasma OPN levels were higher in patients with primary aldosteronism than with essential hypertension. However, the regulatory mechanism of OPN by aldosterone remains unclear. Here, we report the transcriptional regulation of OPN expression by aldosterone and the functional effects of aldosterone-mediated OPN transcription in renal fibroblasts. Aldosterone induced OPN expression in a dose-dependent manner with significant responses at 10 nmol/L (1.6±0.2-fold of controls, P<0.05, n=5) and elicited maximal effects at 10 &mgr;mol/L (3.5±0.4-fold of controls, P<0.01, n=5). Aldosterone increased OPN expression in a time-dependent manner with a maximal effect after 48 hours (2.7±0.3-fold of controls, P<0.01, n=5). This effect was abolished by the mineralocorticoid receptor (MR) antagonist spironolactone. Luciferase promoter deletion assays identified a novel cis regulatory element (−2153 to −1758) in the OPN promoter that is responsive to aldosterone. This element contains an activator protein-1 (AP-1) and nuclear factor kappa B (NF&kgr;B) site. Electrophoretic mobility shift assays, supershift assays, and chromatin immunoprecipitation assays identified both AP-1 and NF&kgr;B as the DNA binding proteins induced by aldosterone with spironolactone inhibiting aldosterone-induced AP-1 or NF&kgr;B activity. OPN-siRNA inhibited completely the induction of cell proliferation, type I, III, and IV collagen synthesis by aldosterone. These results indicate that aldosterone induced MR-mediated OPN expression through AP-1 and NF&kgr;B activation and suggest that aldosterone plays an important role in renal fibrosis through the induction of OPN.

Coexistence of three distinct adrenal tumors in the same adrenal gland in a patient with primary aldosteronism and preclinical Cushing's syndrome.

A 62-year-old woman was admitted to our hospital because of hypokalemia. Physical examination revealed no signs of excessive adrenocortical steroid production, as are found in Cushings syndrome. Her plasma renin activity (PRA) was suppressed (0.10 ng/ml per h), and her serum aldosterone level was high (30.0 ng/dl). PRA was not increased after a renin-releasing test. Her plasma adrenocorticotropic hormone (ACTH) level was low (<5 pg/ml), but her serum cortisol level was normal (21.0 μg/dl). Administration of 8 mg dexamethasone did not suppress her plasma cortisol level. Finally, she was diagnosed with clinical primary aldosteronism associated with preclinical Cushings syndrome. Magnetic resonance image revealed three sequential nodular masses (each 15 mm × 15 mm) in the right adrenal gland. A right adrenalectomy was performed by endoscopy. The three removed tumors appeared to have different characteristics. Microscopic examination revealed that the upper and lower tumors were adrenocortical adenomas, and the middle tumor was a black adenoma. Immunohistochemical staining for the enzymes involved in cortisol biosynthesis suggested that the upper tumor secreted aldosterone, whereas either or both of the two other tumors secreted cortisol. Surprisingly, at 33 years of age, she had been diagnosed with Cushings syndrome, due to a cortisol-producing adrenocortical adenoma, and she had received a left adrenalectomy. Clinically and pathophysiologically, this was a very rare case.

Undercarboxylated osteocalcin is a biomarker of carotid calcification in patients with essential hypertension.

The development of vascular calcification is an active, highly regulated process with similarities to bone formation. Osteocalcin (OC), a vitamin K-dependent protein expressed by osteoblasts, contains 3 γ-carboxyglutamic acid residues derived from the vitamin K-dependent posttranslational modification of glutamic acid residues. Circulating undercarboxylated OC (ucOC) is increased in vitamin K deficiency and serum ucOC is reported to be a clinical marker of vitamin K status. Vitamin K deficiency is associated with vascular calcification as well as osteoporosis. We evaluated the relationship between ucOC and carotid artery calcification in 92 patients with essential hypertension. Ultrasound of the common carotid artery was performed to identify vascular calcification and subjects were divided into 2 groups: a calcification (+) group and a calcification (–) group. Serum creatinine and ucOC levels were higher in the calcification (+) group than in the calcification (–) group and serum ucOC correlated with serum creatinine. To identify the independent determinant factor for carotid artery calcification, we applied both ucOC and estimated glomerular filtration rate as independent factors in logistic regression analysis. Serum ucOC was an independent determinant of carotid calcification, suggesting that circulating ucOC may be an important biomarker of carotid artery calcification.

Association between carotid hemodynamics and asymptomatic white and gray matter lesions in patients with essential hypertension.

The aim of this study was to clarify the magnitude of common carotid artery (CCA) structural and hemodynamic parameters on brain white and gray matter lesions in patients with essential hypertension (EHT). The study subjects were 49 EHT patients without a history of previous myocardial infarction, atrial fibrillation, diabetes mellitus, impaired glucose tolerance, chronic renal failure, symptomatic cerebrovascular events, or asymptomatic carotid artery stenosis. All patients underwent brain MRI and ultrasound imaging of the CCA. MRI findings were evaluated by periventricular hyperintensity (PVH), deep and subcortical white matter hyperintensity (DSWMH), and état criblé according to the Japanese Brain dock Guidelines of 2003. Intima media thickness (IMT), and mean diastolic (Vd) and systolic (Vs) velocities were evaluated by carotid ultrasound. The Vd/Vs ratio was further calculated as a relative diastolic flow velocity. The mean IMT and max IMT were positively associated with PVH, DSWMH, and état criblé (mean IMT: ρ=0.473, 0.465, 0.494, p=0.0007, 0.0014, 0.0008, respectively; max IMT: ρ=0.558, 0.443, 0.514, p=0.0001, 0.0024, 0.0004, respectively). Vd/Vs was negatively associated with état criblé (ρ=−0.418, p=0.0038). Carotid structure and hemodynamics are potentially related to asymptomatic lesions in the cerebrum, and might be predictors of future cerebral vascular events in patients with EHT.

The Relationship Between Osteopontin and Adiponectin in Patients with Essential Hypertension

The renin angiotensin aldosterone system (RAAS) induces inflammation and accelerates atherosclerosis, contributes to both pro- and anti-inflammatory cytokines. Osteopontin (OPN) is known as a pro-inflammatory cytokine and adiponectin is known as an anti-inflammatory cytokine. C-reactive protein (CRP) not only reflects an inflammatory state but also leads to inflammation. Previous studies clarified that OPN and adiponectin were regulated by RAAS. In this study, we hypothesized that plasma OPN level relates to serum adiponectin level in patients with essential hypertension (EHT). Sixty-two patients (32 females) with EHT were enrolled in this study. They were evaluated for conventional risk factors for atherosclerosis, further plasma aldosterone, plasma OPN, serum adiponectin, and CRP levels were assayed. There were significant gender differences in creatinine, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-denisty lipoprotein(LDL) cholesterol, log transformed (ln) adiponectin and ln CRP. Osteopontin was correlated positively with aldosterone and ln CRP (r = 0.277, p = 0.029, r = 0.278, p = 0.029, respectively), negatively with adiponectin (r = −0.346, p = 0.006). Ln adiponectin was correlated positively with HDL cholesterol (r = 0.373, p = 0.003) and negatively with gender (male as 1), creatinine, triglyceride, aldosterone, and ln CRP (r = −0.55, p < 0.001, r = −0.279, p = 0.028, r = −0.406, p = 0.001, r = −0.307, p < 0.015, r = −0.289, p = 0.023, respectively). Stepwise regression analysis showed that adiponectin was an independent predictor of OPN β= −0.0339, p = 0.004). Our results suggest that OPN and adiponectin are related to each other underlying the mechanisms of RAAS and inflammation.