Yasuhisa Okuno

Induction of bone-type alkaline phosphatase in human vascular smooth muscle cells: roles of tumor necrosis factor-alpha and oncostatin M derived from macrophages.

Inflammatory cells such as macrophages and T lymphocytes play an important role in vascular calcification associated with atherosclerosis and cardiac valvular disease. In particular, macrophages activated with cytokines derived from T lymphocytes such as interferon-&ggr; (IFN-&ggr;) may contribute to the development of vascular calcification. Moreover, we have shown the stimulatory effect of 1&agr;,25-dihydroxyvitamin D3 (1,25(OH)2D3) on in vitro calcification through increasing the expression of alkaline phosphatase (ALP), an ectoenzyme indispensable for bone mineralization, in vascular smooth muscle cells. Therefore, we hypothesized that macrophages may induce calcifying phenotype, especially the expression of ALP in human vascular smooth muscle cells (HVSMCs) in the presence of IFN-&ggr; and 1,25(OH)2D3. To test this hypothesis, we used cocultures of HVSMCs with human monocytic cell line (THP-1) or peripheral blood monocytes (PBMCs) in the presence of IFN-&ggr; and 1,25(OH)2D3. THP-1 cells or PBMCs induced ALP activity and its gene expression in HVSMCs and the cells with high expression of ALP calcified their extracellular matrix by the addition of &bgr;-glycerophosphate. Thermostability and immunoassay showed that ALP induced in HVSMCs was bone-specific enzyme. We further identified tumor necrosis factor-&agr; (TNF-&agr;) and oncostatin M (OSM) as major factors inducing ALP in HVSMCs in the culture supernatants of THP-1 cells. TNF-&agr; and OSM, only when applied together, increased ALP activities and in vitro calcification in HVSMCs in the presence of IFN-&ggr; and 1,25(OH)2D3. These results suggest that macrophages may contribute to the development of vascular calcification through producing various inflammatory mediators, especially TNF-&agr; and OSM.

Stiffness indexes beta of the common carotid and femoral arteries are associated with insulin resistance in NIDDM

OBJECTIVE To investigate the association between arterial wall stiffness indexes β of the common carotid artery (CCA) and the femoral artery (FA) and insulin resistance in NIDDM subjects in a cross-sectional study. RESEARCH DESIGN AND METHODS We evaluated the arterial stiffness indexes β of CCA and FA using an ultrasonic phase-locked echo-tracking system in 60 NIDDM subjects attending the diabetes center in Osaka City University Hospital, compared with 120 ageand sex-matched control subjects. Insulin sensitivity indexes were evaluated using a euglycemic-hyperinsulinemic clamp. RESULTS Stiffness indexes β of both CCA and FA were significantly higher in NIDDM subjects than in control subjects (CCA 18.1 ± 0.9 vs. 11.7 ± 0.3, respectively, P < 0.001; FA 35.7 ± 2.3 vs. 23.7 ± 0.8, respectively, P < 0.001). The mean insulin sensitivity index in NIDDM subjects was 4.69 ± 0.29 mg · kg−1 · min−1 · mU−1 · 1. The stiffness indexes β of both CCA and FA were inversely correlated with insulin sensitivity indexes (CCA r = −0.393, P = 0.002; FA r = −0.329, P = 0.010), as well as with age, duration of diabetes, and mean blood pressure. In stepwise multiple regression analyses, insulin sensitivity index and duration of diabetes were identified as significant independent variables for stiffness indexes 3 in both CCA and FA (CCA R2 = 0.249, P = 0.0003; FA R2 = 0.336, P < 0.0001). CONCLUSIONS Arterial stiffness indexes β of CCA and FA were associated with insulin resistance in NIDDM subjects.

Antibodies Against Oxidized LDL and Carotid Artery Intima-Media Thickness in a Healthy Population

Oxidation of LDLs plays an important role in atherosclerosis, and immune response to oxidized LDL (oxLDL) may modulate atherogenesis. Although immunization with oxLDL is shown to suppress atherogenesis in animal models, the role of the immune response to oxLDL is not well established in humans. We investigated the relationship between the titer of anti-oxLDL antibody (oxLDL Ab) and arterial wall thickness in a healthy population with no clinical signs of atherosclerosis. Intima-media thickness of the carotid arteries (CA-IMT) was measured by high-resolution B-mode ultrasonography in 446 healthy subjects. The titer of IgG-class oxLDL Ab was measured by a solid-phase ELISA. In univariate analysis, CA-IMT correlated positively with age, systolic blood pressure, total cholesterol, triglyceride, LDL cholesterol, body mass index, and waist-to-hip ratio, whereas it correlated negatively with HDL cholesterol and oxLDL Ab titer. The inverse association between oxLDL Ab titer and CA-IMT remained significant in multiple regression analysis, which took other confounding variables into account. These results indicate an independent inverse relationship between oxLDL Ab titer and CA-IMT in healthy subjects, supporting the hypothesis that immune response to oxLDL may have a protective role at an early stage of human atherosclerosis.

Angiotensin-Converting Enzyme Gene Polymorphism Is Associated With Carotid Arterial Wall Thickness in Non–Insulin-Dependent Diabetic Patients

BACKGROUND The insertion/deletion (I/D) polymorphism of the ACE gene has been shown to be associated with cardiovascular disease in healthy subjects as well as in patients with non-insulin-dependent diabetes mellitus (NIDDM). We investigated the relationship between the ACE gene polymorphism and the wall thickness of both carotid and femoral arteries in NIDDM patients. METHODS AND RESULTS We measured the intimal plus medial thickness (IMT) of both carotid and femoral arteries using high-resolution B-mode ultrasonography in 288 Japanese NIDDM patients (160 men, 128 women). No significant differences among the three genotypes were found with respect to age, sex, duration of diabetes, body mass index, blood pressure, plasma glucose, hemoglobin AIC, total cholesterol, triglycerides, HDL cholesterol, or cigarette-years. Plasma ACE levels were strongly associated with I/D polymorphism, with an additive effect of the D alleles. The carotid IMT of the patients carrying the D allele (DD+ID genotype) was significantly higher than that of the patients not carrying the D allele (II genotype) (P = .037), whereas the femoral IMT was not affected by the I/D polymorphism. Multiple regression analysis demonstrated that the risk factors for carotid IMT of patients with NIDDM were age, non-HDL cholesterol, and D allele of the ACE gene (R2 = .155, P < .0001). CONCLUSIONS The D allele of the ACE gene may be a risk factor for the development of wall thickening of the carotid but not the femoral artery in NIDDM patients.

Effect of Polymorphism of Apolipoprotein E and Angiotensin-Converting Enzyme Genes on Arterial Wall Thickness

We examined the association between the polymorphism of the apolipoprotein E (apoE) and the ACE genes and the intima-media thickness (IMT) of the carotid and femoral arteries measured using ultrasonography. The values of IMT of each artery were significantly higher in NIDDM patients (n = 356) than in control subjects (n = 235). The E4 allele or the D allele did not affect clinical characteristics, including age, fasting plasma glucose, total cholesterol, HDL cholesterol, LDL cholesterol, or blood pressure, in NIDDM or control subjects. No difference in the carotid IMT value was noted among the apoE genotypes in control or diabetic subjects. The carotid IMT was significantly higher in diabetic patients with the DD genotype (1.200 ± 0.586 mm) than in those with the II genotypes (0.990 ± 0.364 mm). Neither the E4 allele nor the D allele affected the femoral IMT in control or diabetic subjects. Multiple regression analysis demonstrated that the carotid IMT of NIDDM patients was associated with age, the D allele, and LDL cholesterol but not with the E4 allele, whereas that of control subjects was associated with age, sex, systolic blood pressure, LDL cholesterol, and HDL cholesterol, inversely. These results suggested that the E4 allele was not associated with the carotid or femoral IMTs, but that the D allele was statistically associated with carotid IMT in NIDDM patients but not control subjects. However, since the association was weak (2.3% explanatory power), its biological significance remains to be determined.

Regional Arterial Stiffness in Patients with Type 2 Diabetes and Chronic Kidney Disease

Increased arterial stiffness is an independent predictor of death from cardiovascular disease, and aortic stiffness is more predictive than stiffness of other arterial regions. Because little is known about the effect of chronic kidney disease (CKD) on regional arterial stiffness, pulse wave velocity (PWV) of four different arterial segments was measured in patients who had type 2 diabetes with and without various stages of CKD. A total of 434 patients had type 2 diabetes, and there were 192 healthy control subjects who were comparable in age and gender. GFR was estimated by the abbreviated Modification of Diet in Renal Disease equation. The patients with diabetes were classified into CKD stages by the definition of the Kidney Disease Outcomes Quality Initiative guidelines. PWV was measured in the heart-femoral, heart-carotid, heart-brachial, and femoral-ankle segments simultaneously using an automatic pulse wave analyzer. PWV of each arterial region was increased in patients who had diabetes without kidney damage and was increased further in a stepwise manner with the advanced stages of CKD. The increase in PWV was greater in the heart-femoral and heart-carotid regions than in the heart-brachial and femoral-ankle segments. However, after adjustment for age, BP, and other confounding factors using a multiple regression model, decreased GFR was independently associated with increased PWV of the heart-femoral region but not with PWV of other arterial segments. In type 2 diabetes, CKD was associated with increased stiffness of arteries, particularly of the aorta. The cross-sectional result may explain the increased risk for cardiovascular disease in CKD, although longitudinal studies are needed to confirm it.

Fibrillar Collagen Specifically Regulates Human Vascular Smooth Muscle Cell Genes Involved in Cellular Responses and the Pericellular Matrix Environment

Abstract— Proliferation and &agr;v&bgr;3 integrin-dependent migration of vascular smooth muscle cells are suppressed on polymerized type I collagen. To identify genes specifically regulated in human smooth muscle cells by polymerized collagen, we used the suppressive subtraction hybridization technique. Compared with smooth muscle cells cultured on monomer collagen, polymerized collagen suppresses the following: (1) a number of other extracellular matrix proteins, including fibronectin, thrombospondin-1, tenascin-C, and cysteine-rich protein 61; (2) actin binding proteins including &agr;-actinin; (3) signaling molecules; (4) protein synthesis-associated proteins; and (5) genes with unknown functions. Some of the identified genes, including cysteine-rich protein 61, show unique kinetics of mRNA regulation by monomer or polymerized collagen distinct from growth factors, suggesting extracellular matrix-specific gene modulation. Moreover, in vivo balloon catheter-mediated injury to the rat carotid artery induces many of the genes that are suppressed by polymerized collagen. Protein levels of thrombospondin-1 and fibronectin are also suppressed by polymerized collagen. Thrombospondin-1-mediated smooth muscle cell migration on vitronectin is significantly inhibited after culture on polymerized collagen for 24 hours, which is associated with decreased &agr;-actinin accumulation at focal adhesions. Thus, polymerized type I collagen dynamically regulates gene expression, pericellular accumulation of extracellular matrix molecules, and the response to a given matrix molecule.

Femoral artery wall thickness and stiffness in evaluation of peripheral vascular disease in type 2 diabetes mellitus.

Stiffening and thickening of arterial wall are two important components of atherosclerosis. The purpose of this study was to evaluate the effects of femoral artery wall stiffness on clinical manifestation of peripheral vascular disease (PVD) in type 2 diabetes mellitus. The subjects were 315 patients with type 2 diabetes. Presence of intermittent claudication and/or leg pain at rest and reduced ankle-brachial blood pressure index (ABI<0.9) were used as a subjective and an objective index of PVD, respectively. Femoral artery intima-media thickness (FA-IMT) and stiffness parameter beta (FA-stiffness beta) were measured by ultrasound methods. Symptomatic patients (N=58) showed greater values for both FA-IMT and FA-stiffness beta than those without symptom (N=257). Similarly, patients with reduced ABI (N=56) had greater FA-IMT and FA-stiffness beta than those without (N=259). However, correlation between FA-IMT and FA-stiffness beta was not impressive, especially in the symptomatic patients. To evaluate the effect of FA-stiffness beta on PVD symptoms, the subjects were divided into three subgroups according to FA-IMT, and then FA-stiffness beta was compared between those with and without PVD symptoms in each subgroup. The symptomatic patients had greater FA-stiffness beta values than the asymptomatic subjects in all the three subgroups. Multiple logistic regression analysis indicated that the presence of PVD symptoms was associated more closely with increased FA-stiffness beta than with increased FA-IMT, whereas reduced ABI was associated more closely with FA-IMT than with FA-stiffness beta. These data suggest that stiffening of arterial wall has a significant impact on PVD manifestations, particularly on the leg symptoms, in patients with type 2 diabetes.

Impaired Retinal Artery Blood Flow in IDDM Patients Before Clinical Manifestations of Diabetic Retinopathy

OBJECTIVE To determine whether hemodynamic changes in retinal arteries precede clinical manifestations of diabetic retinopathy and to examine the effects of control of hyperglycemia on retinal artery blood flow. RESEARCH DESIGN AND METHODS We assessed blood flow in bilateral central retinal arteries in 50 insulin-dependent diabetes mellitus (IDDM) patients without retinopathy and 20 sex- and age-matched control subjects using duplex Doppler sonography. We determined the peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged velocity (TAV), resistance index (RI), and pulsatility index (PI). RESULTS PSV, EDV, and TAV were significantly lower in IDDM patients than in control subjects (P < 0.05, P < 0.01, and P < 0.01, respectively). The RI was significantly higher in IDDM patients than in control subjects (P < 0.01) and was significantly correlated with plasma levels of glucose in IDDM patients (r = 0.0.310, P = 0.0248). Multiple regression analysis identified the plasma levels of glucose as a significant determination of RI in IDDM patients. After 14 days of intensive insulin therapy in 7 IDDM patients, the RI and plasma levels of glucose showed significant decreases (P = 0.018, P = 0.001, respectively). CONCLUSIONS Our results showed that changes in retinal hemodynamics were present before the clinical detection of overt diabetic retinopathy and suggest that the presence of short-term hyperglycemia partly contributes to impaired retinal circulation.

Renal function and insulin resistance as determinants of plasma leptin levels in patients with NIDDM.

Summary Plasma leptin level is known to correlate with the degree of obesity. To determine the influences of renal fuction and insulin resistance on plasma leptin concentrations, we measured plasma leptin concentrations and performed the euglycaemic hyperinsulinaemic clamp studies in 57 patients with non-insulin-dependent diabetes mellitus with a wide range of renal function. In simple regression analyses, plasma leptin concentration showed significant positive correlations with percentage of body fat measured by dual energy X-ray absorptiometry, body mass index, waist to hip ratio and fasting plasma insulin. Leptin level was higher in females than males. Multiple regression analyses indicated that percent body fat, waist to hip ratio, plasma insulin, gender and renal function (1/creatinine), but not insulin sensitivity, were significant and independent determinants of plasma leptin level. These results suggest that plasma leptin level is regulated or affected by multiple factors including renal function. Insulin resistance appeared to increase leptin levels indirectly by raising plasma insulin. [Diabetologia (1997) 40: 676–679]