Masanori Emoto

Insulin Resistance as an Independent Predictor of Cardiovascular Mortality in Patients with End-Stage Renal Disease

Insulin resistance is closely associated with atherosclerosis and cardiovascular mortality in the general population. Patients with end-stage renal disease (ESRD) are known to have insulin resistance, advanced atherosclerosis, and a high cardiovascular mortality rate. We evaluated whether insulin resistance is a predictor of cardiovascular death in a cohort of ESRD. A prospective observational cohort study was performed in 183 nondiabetic patients with ESRD treated with maintenance hemodialysis. Insulin resistance was evaluated by the homeostasis model assessment method (HOMA-IR) using fasting glucose and insulin levels at baseline, and the cohort was followed for a mean period of 67 mo. Forty-nine deaths were recorded, including 22 cardiovascular deaths. Cumulative incidence of cardiovascular death by Kaplan-Meier estimation was significantly different between subjects in the top tertile of HOMA-IR (1.40 to 4.59) and those in the lower tertiles of HOMA-IR (0.28 to 1.39), and the hazard ratio (HR) was 2.60 (95% confidence interval [CI], 1.12 to 6.01; P = 0.026) in the univariate Cox proportional hazards model. In multivariate Cox models, the positive association between HOMA-IR and cardiovascular mortality remained significant (HR, 4.60; 95% CI, 1.83 to 11.55; P = 0.001) and independent of age, C-reactive protein, and presence of preexisting vascular complications. Further analyses showed that the effect of HOMA-IR on cardiovascular mortality was independent of body mass index, hypertension, and dyslipidemia. In contrast, HOMA-IR did not show such a significant association with noncardiovascular mortality. These results indicate that insulin resistance is an independent predictor of cardiovascular mortality in ESRD.

Plasma Level of Endogenous Secretory RAGE Is Associated With Components of the Metabolic Syndrome and Atherosclerosis

Objective—Advanced glycation endproducts, AGEs, and its specific receptor, RAGE, are involved in diabetic vascular complications. Endogenous secretory RAGE, esRAGE, has been identified as an alternatively spliced form of RAGE, and shown to act as a decoy receptor for AGE. Here, we measured plasma esRAGE level with a recently developed enzyme-linked immunosorbent assay (ELISA) and examined its association with atherosclerosis in age- and gender-matched 203 type 2 diabetic and 134 nondiabetic subjects. Methods and Results—Plasma esRAGE was inversely associated with carotid or femoral atherosclerosis, as quantitatively measured as intimal-medial thickness (IMT) by arterial ultrasound. Stepwise regression analyses revealed that plasma esRAGE was the third strongest and independent factor associated with carotid IMT, following age and systolic blood pressure. Plasma esRAGE was significantly lower in diabetic patients (0.176±0.092 ng/mL) than nondiabetic controls (0.253±0.111). Of note, in all, diabetic or nondiabetic group, plasma esRAGE was significantly and inversely correlated with components of the metabolic syndrome including body mass index, blood pressure, triglyceride, HbA1c, or an insulin resistance index. Stepwise regression analyses showed that body mass index or insulin resistance index was the major factor determining plasma esRAGE in all, nondiabetic or diabetic population. Conclusions—esRAGE is a novel and potential protective factor for the metabolic syndrome and atherosclerosis.

Inverse relationship between circulating oxidized low density lipoprotein (oxLDL) and anti-oxLDL antibody levels in healthy subjects

Oxidized low density lipoprotein (oxLDL) has been implicated in the pathogenesis of atherosclerosis. Recent studies have shown that immunization of animals with oxLDL results in suppression of atherogenesis. Antibody against oxLDL (oxLDL Ab) is detectable in human sera, although its biological significance is not well established. We examined the relationship between oxLDL Ab titer and circulating oxLDL level in 130 healthy Japanese subjects. OxLDL was measured as apolipoprotein (apo) B-containing lipoproteins carrying oxidized phosphatidylcholines by a sensitive ELISA. IgG class oxLDL Ab titer was measured by ELISA. Plasma oxLDL concentration was very low and it corresponded on average to one to two out of 1000 apoB-containing lipoproteins in plasma. Plasma oxLDL correlated positively with LDL cholesterol and inversely with oxLDL Ab titer. These associations remained significant and independent in multiple regression analysis including age, gender, smoking, and high-density lipoprotein cholesterol. These data indicate that healthy subjects have a very low concentration of oxLDL in the circulation, and that oxLDL Ab titer is in an inverse relationship with plasma oxLDL concentration in this population. Although these results suggest that oxLDL Ab may play a role in maintaining the low level of plasma oxLDL, its role in atherogenesis awaits further studies.

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.

Platelet P-Selectin Expression Is Associated With Atherosclerotic Wall Thickness in Carotid Artery in Humans

Background—Recent genetic animal models reveal important roles of platelet P-selectin on progression of atherosclerosis. In the present study, we examine the relation between platelet P-selectin expression and atherosclerotic parameters in 517 subjects. Methods and Results—Unrelated subjects (n=517; 235 male and 282 female), including 187 with type 2 diabetes, 184 with hypertension, and 366 with hyperlipidemia, were enrolled in the study. P-selectin expression was determined by whole-blood flow cytometry. Arterial stiffness (stiffness index &bgr;) and arterial wall thickness (intima-media thickness [IMT]) were determined by carotid ultrasound. P-selectin expression was significantly and positively correlated with carotid IMT and stiffness index &bgr;. Multiple regression analyses showed that the association of the percentage of P-selectin–positive platelets with carotid IMT was independent of other clinical factors. Moreover, the percentage of P-selectin–positive platelets was higher in subjects with carotid plaque and was an independent factor associated with occurrence of carotid plaque analyzed by multiple logistic regression analysis. Finally, the percentage of P-selectin–positive platelets was positively associated with age, body mass index, systolic and diastolic blood pressure, and HbA1c and inversely associated with HDL cholesterol. Conclusions—Platelet P-selectin is independently associated with atherosclerotic arterial wall changes in human subjects.

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.

Fetuin-A: a multifunctional protein.

Sixty-six years have elapsed since the discovery of fetuin in 1944, but its importance in mammalian physiology has only recently been appreciated. Fetuin, first isolated from fetal bovine serum and now most commonly known as either fetuin-A, alpha-2-HS-glycoprotein (recommended name by UniprotKB and PIR), or α2-Heremans-Schmid glycoprotein, functions as an important component of diverse normal and pathological processes, including vascular calcification and bone metabolism regulation, insulin resistance, protease activity control, keratinocytes migration, and breast tumor cell proliferative signaling. Fetuin-A has also been identified as a biomarker for neurodegenerative disease. Here, we summarize recent publications focusing on the structural and functional properties of fetuin-A. The emerging importance of fetuin-A for both diagnosis and therapeutics has come to the attention of the pharmaceutical industry. Therefore, we will discuss the status of patents based on fetuin-A.

Decrease in carotid intima-media thickness in hypothyroid patients after normalization of thyroid function

objective  This case–control study was carried out to assess whether levothyroxine (L‐T4) replacement might cause regression of the enhanced atherosclerosis seen in hypothyroid patients.

HOMA Index to Assess Insulin Resistance in Renal Failure Patients

Insulin resistance plays an important role in multiple risk factor syndrome, clustering of multiple risk factors including glucose intolerance, dyslipidemia and hypertension that could promote atherosclerosis. Patients with chronic renal failure show insulin resistance [1], clustering of these risk factors and advanced atherosclerosis [2]. Since insulin resistance index by homeostasis model assessment (HOMA-IR) closely mirrors the insulin resistance by the standard glucose clamp (Clamp-IR) [3, 4], we examined the usefulness of HOMA-IR in patients with renal failure. The subjects were 113 type 2 diabetes patients (72 men and 41 women), treated with lifestyle modification alone (n = 32), oral hypoglycemic agents (n = 53), or insulin injection (n = 28). Median (range) age, BMI, duration of diabetes and HbA1c were 57 (15–71) years, 22.8 (14.6–34.3) kg/m2, 8 (0.1–30) years, and 8.5% (4.6–13.4%), respectively. They were divided into two categories by serum creatinine levels: group 1 with normal serum creatinine levels (median 0.7 (range 0.3–0.9) mg/ dl, n = 96) and group 2 with increased serum creatinine (3.1 (2.0–8.1) mg/dl, n = 17). Clamp-IR by the euglycemic hyperinsulinemic clamp method was expressed as glucose infusion rate (mg/kg body weight/min) divided by steady-

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.