Daijiro Enomoto

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.

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.

Hyperhomocysteinemia is one of the risk factors associated with cerebrovascular stiffness in hypertensive patients, especially elderly males

Hyperhomocystemia has been reported to be associated with cardiovascular disease, especially stroke. The resistive index (RI) estimated by carotid ultrasound is an established variable for estimating the risk of cerebral infarction. The aim of this study was to evaluate the relationship between homocysteine concentration and carotid RI, a marker of cerebral vascular resistance in essential hypertensive patients. We measured serum total homocysteine and carotid RI in 261 patients. Multiple linear regression analysis was used to determine the association of homocysteine with carotid RI and intima media thickness (IMT). Age, sex, BMI, systolic blood pressure (SBP), homocysteine, total cholesterol, high density lipoprotein-cholesterol (HDL-C), uric acid, CRP, HbA1c, estimated glomerular filtration rate, and use of antihypertensive agents were included as independent variables. Age, sex, use of antihypertensive agents, HDL-C and homocysteine levels were shown to be significant predictors of carotid RI, but not IMT. Multiple regression analysis in men older than 65 years showed homocysteine and SBP were associated significantly with carotid RI. In elderly male patients, homocysteine was the strongest predictor of carotid RI (B = 0.0068, CI = 0.0017–0.0120, P = 0.011) in the multivariate model. In conclusion, hyperhomocysteinemia is associated with carotid RI, a surrogate marker of cerebral vascular resistance, especially in elderly men.

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.

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.

Osteopontin deficiency reduces kidney damage from hypercholesterolemia in Apolipoprotein E-deficient mice

Hypercholesterolemia is a well-established risk factor for kidney injury, which can lead to chronic kidney disease (CKD). Osteopontin (OPN) has been implicated in the pathology of several renal conditions. This study was to evaluate the effects of OPN on hypercholesterolemia induced renal dysfunction. Eight-week-old male mice were divided into 4 groups: apolipoprotein E knockout (ApoE−/−) and ApoE/OPN knockout (ApoE−/−/OPN−/−) mice fed a normal diet (ND) or high cholesterol diet (HD). After 4 weeks, Periodic acid-Schiff (PAS) and oil red O staining revealed excessive lipid deposition in the glomeruli of ApoE−/−HD mice, however, significantly suppressed in ApoE−/−/OPN−/−HD mice. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression was lower in the glomeruli of ApoE−/−/OPN−/−HD mice than ApoE−/−HD mice. In vitro study, primary mesangial cells were incubated with recombinant mouse OPN (rmOPN). RmOPN induced LOX-1 mRNA and protein expression in primary mesangial cells. Pre-treatment with an ERK inhibitor suppressed the LOX-1 gene expression induced by rmOPN. These results indicate that OPN contributes to kidney damage in hypercholesterolemia and suggest that inhibition of OPN may provide a potential therapeutic target for the prevention of hypercholesterolemia.

Effects of amlodipine and candesartan on arterial stiffness estimated by cardio-ankle vascular index in patients with essential hypertension: A 24-week study.

BACKGROUND Aortic stiffness assessed by brachio-ankle pulse wave velocity (baPWV) can be used to predict cardiovascular events. However, baPWV is dependent on blood pressure. Antihypertensive drugs have been reported to reduce baPWV; but it is difficult to determine if this effect is associated with lowered blood pressure or reduced arterial stiffness. OBJECTIVES The primary end point of this study was to assess whether antihypertensive drugs reduce arterial stiffness as estimated by cardio-ankle vascular index (CAVI). The secondary end point was to compare the effects of 2 widely used drugs, the calcium-channel blocker amlodipine and the angiotensin II receptor blocker candesartan, on arterial stiffness. METHODS Between October 2005 and September 2006, consecutive Japanese outpatients with essential hypertension (EHT) (defined as using antihypertensive drugs at screening, systolic blood pressure [SBP] > 140 mm Hg, or diastolic BP [DBP] >90 mm Hg) were assigned to treatment for 24 weeks with either amlodipine (5-10 mg/d) or candesartan (8-12 mg/d). Arterial stiffness was evaluated with CAVI before and after 24 weeks of treatment. Relative change in arterial stiffness from baseline was also compared. The evaluator was blinded to treatment. RESULTS Twenty patients (11 men, 9 women; mean [SD] age, 62 [10] years) were included in the study. There were no significant differences in clinical characteristics between the 2 groups. At baseline, mean (SD) CAVI was not significantly different in the amlodipine group compared with the candesartan group (8.93 [0.93] vs 8.46 [1.34], respectively). During the 24-week treatment period, mean SBP and DBP decreased significantly in both the amlodipine (14/10 mm Hg; P = 0.006 and P = 0.005) and the candesartan groups (13/11 mm Hg; P = 0.033 and P = 0.005). Amlodipine was associated with a significant change in CAVI from baseline (8.93 [0.93] vs 8.60 [1.50]; P = 0.017), whereas candesartan was not (8.46 [1.34] vs 8.81 [1.20]). The percentage change in CAVI was significantly different in the amlodipine group compared with the candesartan group (-7.14 [8.83] vs 5.85 [16.0], respectively; P = 0.038). After 24 weeks of treatment, the CAVI of the amlodipine group was still numerically larger than baseline CAVI of the candesartan group, although the difference was not statistically significant. Furthermore, there was no significant difference in absolute CAVI between the 2 groups after 24 weeks, but the relative change from baseline was significant in favor of amlodipine. Logistic regression analysis revealed that amlodipine improved CAVI independent of its antihypertensive effect. CONCLUSION These data suggest that amlodipine and candesartan had different effects on aortic stiffness estimated by CAVI, despite similar effects on brachial blood pressure after 24 weeks of treatment in these Japanese patients with EHT.

Osteopontin plays a critical role in interstitial fibrosis but not glomerular sclerosis in diabetic nephropathy.

Background/Aims: Osteopontin (OPN) has been implicated in the pathology of several renal conditions. The aim of this study was to clarify the roles of OPN in diabetic nephropathy. Methods: Diabetes mellitus (DM) was induced in wild-type (WT) and OPN knockout (KO) mice by injecting streptozotocin. The mice were killed 20 weeks after induction of DM and their kidneys removed. Results: Renal mRNA expression of OPN was increased in WT-DM mice compared to WT-sham mice. Immunohistochemistry showed high levels of OPN expression in the proximal tubules of WT-DM mice. Kidney weight and urinary albumin excretion increased to similar levels in the WT-DM and KO-DM mice. Interstitial fibrosis was increased in WT-DM mice compared to KO-DM mice. However, there were no differences in the degree of mesangial expansion or glomerular hypertrophy between the two groups. F4/80-positive cells (macrophages) and FSP-1-positive cells (fibroblasts) showed significantly higher infiltration in WT-DM mice than in KO-DM mice. Renal mRNA expression of NADPH oxidase subunits and urinary 8-isoprostane excretion were also increased in WT-DM mice. Conclusions: These results indicated that OPN is a key molecule that induces interstitial fibrosis in the diabetic kidney, but does not induce glomerular sclerosis.

Comparison of the Effect of Combination Therapy with an Angiotensin II Receptor Blocker and Either a Low-Dose Diuretic or Calcium Channel Blocker on Cardiac Hypertrophy in Patients with Hypertension

Left ventricular hypertrophy (LVH) regression is an important issue in hypertensive patients. Patients with LVH who had received the angiotensin receptor blocker (ARB) treatment for 8 weeks and had not reached the target blood pressure level were enrolled in the study. Patients were assigned to either losartan (50 mg)/hydrochlorothiazide (HCTZ, 12.5 mg) group or ARB + CCB group (usual dose of ARB and calcium channel blocker, CCB). After 48 weeks, LV mass index was found to be reduced significantly in the losartan/HCTZ group but not in the ARB + CCB group. These results suggest that combination therapy of an ARB and diuretic has greater potential to cause regression compared with an ARB and CCB.

Case of membranoproliferative glomerulonephritis due to essential cryoglobulinemia without hepatitis C virus infection

An 81‐year‐old man was admitted to our hospital because of leg edema. Serological studies for anti‐neutrophil cytoplasmic antibody (ANCA), anti‐double stranded DNA antibodies, and antibodies to hepatitis C and B were negative. Severe hypocomplementemia was present and a cryoglobulin was detected with serum immunoelectrophoresis being positive for the immunoglobulin (Ig)M κ type. The cryoglobulin was characterized by immunoelectrophoresis which showed that the protein was composed of polyclonal IgG and κ‐type monoclonal IgM. A diagnosis of essential type II cryoglobulinemia was made and the patient underwent a renal biopsy. The renal biopsy revealed endocapillary and mesangial cell proliferation with increased matrix. The resultant lobular appearance of the glomerulus and double contours of the basement membrane were indicative of membranoproliferative glomerulonephritis (MPGN). Immunofluorescence studies demonstrated granular staining in the capillary wall for IgG, IgA, IgM and C4 with little C3 deposition but no C1q. He was finally diagnosed with MPGN due to mixed cryoglobulinemia type II. MPGN with essential cryoglobulinemia type II without evidence of hepatitis C virus infection, like that found in the present case, is very rare.