Circulating oxidised low-density lipoprotein and intercellular adhesion molecule-1 and risk of type 2 diabetes mellitus: the Atherosclerosis Risk in Communities Study

Protective effects of paraoxonase-1, vitamin E and selenium, and oxidative stress index on the susceptibility of low density lipoprotein to oxidation in diabetic patients with/without coronary artery disease

BACKGROUND

The oxidative modification of low density lipoprotein (LDL) is closely associated with an increased risk for coronary artery disease (CAD) in diabetic patients. The purpose of this study is to investigate the relation between serum vitamin E and selenium, paraoxonase-1 (PON1) activity, total antioxidant capacity (TAC), total oxidant status (TOS), malondialdehyde (MDA), and oxidative stress index (OSI) values with the susceptibility of LDL to oxidative modification and the possibility of CAD in diabetic patients.

METHOD

This study was designed as a case control survey of 82 diabetes patients divided into two groups including T2DM alone (as group I) and both T2DM and CAD (as group II). Fasting blood samples were taken to the assay of fasting blood glucose (FBG), HbA1c, total cholesterol (TC), TAC, TOS, MDA, OSI, vitamin E, selenium, oxidized low density lipoprotein (Ox-LDL), and activity of PON1.

RESULTS

Ox-LDL, MDA, TOS, and OSI values in groups II were significantly higher compared with group I (all with P value = 0.000). TAC, vitamin E, selenium, and PON1 activity values were significantly lower in group II compared with groups I (P value = 0.000; P value = 0.000; P value = 0.007; P value = 0.003, respectively). There were significant relationships between the amounts of TAC, TOS, OSI, and vitamin E with the amounts of PON1 activity and Ox-LDL (p < 0.05). But Ox-LDL and PON1 activity correlated weakly with together (p = 0.094).

CONCLUSION

Results of this study support the belief that oxidative stress might be an important etiologic factor which makes some diabetics more susceptible to CAD. Increased oxidative stress may be a potential therapeutic target in the prevention and management of CAD in diabetic patients.

Clonal hematopoiesis as a novel risk factor for type 2 diabetes mellitus in patients with hypercholesterolemia

Introduction

Clonal hematopoiesis of indeterminate potential (CHIP) is associated with atherosclerosis and cardiovascular disease. It has been suggested that CHIP may be related to diabetes, so we investigated the association between CHIP and new-onset type 2 diabetes.

Methods

This study included 4,047 subjects aged >=40 years without diabetes. To detect CHIP, targeted gene sequencing of genomic DNA from peripheral blood cells was performed. The incidence of new-onset type 2 diabetes during the follow-up period was evaluated.

Results

Of the total subjects, 635 (15.7%) had CHIP. During the median follow-up of 5.1 years, the incidence of new-onset diabetes was significantly higher in CHIP carriers than in subjects without CHIP (11.8% vs. 9.1%, p = 0.039). In a univariate analysis, CHIP significantly increased the risk of new-onset diabetes (HR 1.32, 95% CI 1.02-1.70, p = 0.034), but in a multivariate analysis, it was not significant. The CHIP-related risk of new onset diabetes differed according to LDL cholesterol level. In the hyper-LDL cholesterolemia group, CHIP significantly increased the risk of diabetes (HR 1.64, 95% CI 1.09-2.47, p = 0.018), but it did not increase the risk in the non-hyper-LDL cholesterolemia group. The subjects with CHIP and hyper-LDL-cholesterolemia had approximately twice the risk of diabetes than subjects without CHIP and with low LDL cholesterol (HR 2.05, 95% CI 1.40-3.00, p < 0.001).

Conclusion

The presence of CHIP was a significant risk factor for new-onset type 2 diabetes, especially in subjects with high LDL cholesterol. These results show the synergism between CHIP and high LDL cholesterol as a high-risk factor for diabetes.

Association between circulating oxidized OxLDL/LDL-C ratio and the severity of coronary atherosclerosis, along with other emerging biomarkers of cardiovascular disease in patients with type 2 diabetes

AIMS

The aim of this study was to evaluate the association between circulating oxLDL/LDL-C ratio and the severity of coronary atherosclerosis, along with other emerging biomarkers of cardiovascular disease (CVD) in patients with type 2 diabetes.

METHODS

We recruited 152 patients with type 2 diabetes for our study. ELISA measured the plasma levels of oxLDL and other biomarkers. The severity of coronary lesions was evaluated using Gensini scores, which were calculated based on results of coronary computed tomographic angiography (CCTA). All patients were allocated into four groups according to CCTA findings and Gensini score: normal group (score = 0), mild coronary atherosclerosis group (0 < scores ≤ 3), moderate coronary atherosclerosis group (3.01 ≤ scores ≤ 32.67) and severe coronary atherosclerosis group (32.68 ≤ scores ≤ 180). Association between the oxLDL/LDL-C ratio and the severity of coronary atherosclerosis were evaluated using logistic regression models.

RESULTS

Multivariate logistic regression analysis showed that the oxLDL/LDL-C ratio was positively associated with severity of coronary atherosclerosis (OR 2.03, 95% CI 1.31-3.14, p < 0.01). Interleukin 33 (IL33) correlated positively with oxLDL/LDL-C ratio (r = 0.274, p < 0.01). However, vascular cell adhesion molecular-1 (VCAM-1) had similar trends with oxLDL/LDL-C ratio in these 4 groups.

CONCLUSIONS

OxLDL/LDL-C ratio is considered as a potential biomarker in patients with diabetes for early recognition and intervention of severe coronary atherosclerosis, and will be more effective if tested IL33 and VCAM-1 at the same time.

Association between lipid peroxidation and risk of type 2 diabetes in women

In-vitro and animal studies demonstrate that lipid peroxidation plays an important role in the pathogenesis of type 2 diabetes (T2D). However, human data from prospective studies are limited and contradictory. We used data originally collected in two nested case-control studies of cancer to prospectively evaluate whether systemic levels of lipid peroxidation were associated with incidence of T2D in 1917 women who were 40-70 years old and diabetes-free at baseline. Lipid peroxidation was measured by urinary F₂-isoprostanes (F₂-IsoPs) and its major metabolite 2,3-dinor-5,6-dihydro-15-F_2t-IsoP (F₂-IsoP-M) with GC/NICI-MS assays. The Cox regression model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident T2D. After a median follow-up of 10.1 years, 187 women were diagnosed with T2D. Urinary concentrations of both F₂-IsoPs and F₂-IsoP-M were significantly higher in T2D cases than in non-cases. Both biomarkers were positively associated with subsequent risk of T2D in multivariable-adjusted Cox models. When further adjusted for body mass index (BMI), the positive association with F₂-IsoP-M was attenuated and no longer statistically significant, whereas the association with F₂-IsoPs remained (P for overall significance < 0.001). HR for T2D was 1.68 (95% CI: 1.13, 2.51) for the highest vs the lowest quartile of F₂-IsoPs. Moreover, this association appeared more pronounced among women with higher BMI. In summary, our study suggests that F₂-IsoPs could be of significance in T2D risk prediction among middle-aged and elderly women.

The Reciprocal Relationship between LDL Metabolism and Type 2 Diabetes Mellitus

Type 2 diabetes mellitus and insulin resistance feature substantial modifications of the lipoprotein profile, including a higher proportion of smaller and denser low-density lipoprotein (LDL) particles. In addition, qualitative changes occur in the composition and structure of LDL, including changes in electrophoretic mobility, enrichment of LDL with triglycerides and ceramides, prolonged retention of modified LDL in plasma, increased uptake by macrophages, and the formation of foam cells. These modifications affect LDL functions and favor an increased risk of cardiovascular disease in diabetic individuals. In this review, we discuss the main findings regarding the structural and functional changes in LDL particles in diabetes pathophysiology and therapeutic strategies targeting LDL in patients with diabetes.

Reduced oxidized LDL in T2D plaques is associated with a greater statin usage but not with future cardiovascular events

Background

Type 2 diabetes (T2D) patients are at a greater risk of cardiovascular events due to aggravated atherosclerosis. Oxidized LDL (oxLDL) has been shown to be increased in T2D plaques and suggested to contribute to plaque ruptures. Despite intensified statin treatment during the last decade the higher risk for events remains. Here, we explored if intensified statin treatment was associated with reduced oxLDL in T2D plaques and if oxLDL predicts cardiovascular events, to elucidate whether further plaque oxLDL reduction would be a promising therapeutic target.

Methods

Carotid plaque OxLDL levels and plasma lipoproteins were assessed in 200 patients. Plaque oxLDL was located by immunohistochemistry. Plaque cytokines, cells and scavenger receptor gene expression were quantified by Luminex, immunohistochemistry and RNA sequencing, respectively. Clinical information and events during follow-up were obtained from national registers.

Results

Plaque oxLDL levels correlated with markers of inflammatory activity, endothelial activation and plasma LDL cholesterol (r = 0.22-0.32 and p ≤ 0.01 for all). T2D individuals exhibited lower plaque levels of oxLDL, sLOX-1(a marker of endothelial activation) and plasma LDL cholesterol (p = 0.001, p = 0.006 and p = 0.009). No increased gene expression of scavenger receptors was identified in T2D plaques. The lower oxLDL content in T2D plaques was associated with a greater statin usage (p = 0.026). Supporting this, a linear regression model showed that statin treatment was the factor with the strongest association to plaque oxLDL and plasma LDL cholesterol (p < 0.001 for both). However, patients with T2D more frequently suffered from symptoms and yet plaque levels of oxLDL did not predict cardiovascular events in T2D (findings are summarized in Fig. 1a).

Conclusions

This study points out the importance of statin treatment in affecting plaque biology in T2D. It also implies that other biological components, beyond oxLDL, need to be identified and targeted to further reduce the risk of events among T2D patients receiving statin treatment.

Circulating Soluble CD36 is Similar in Type 1 and Type 2 Diabetes Mellitus versus Non-Diabetic Subjects

The aim of this study was to determine whether plasma concentrations of sCD36 (soluble CD36) are associated with the presence of type 1 or type 2 diabetes. Plasma levels of sCD36 were analysed in 1023 subjects (225 type 1 diabetes (T1D) patients, 276 type 2 diabetes (T2D) patients, and 522 non-diabetic control subjects) using an enzyme-linked immunosorbent assay (ELISA). Multinomial and logistic regression models were performed to evaluate associations with sCD36 and its association with diabetes types. There were no significant differences in sCD36 (p = 0.144) among study groups, neither in head-to-head comparisons: non-diabetic versus T1D subjects (p = 0.180), non-diabetic versus T2D subjects (p = 0.583), and T1D versus T2D patients (p = 0.151). In the multinomial model, lower sCD36 concentrations were associated with older age (p < 0.001), tobacco exposure (p = 0.006), T2D (p = 0.020), and a higher-platelets count (p = 0.004). However, in logistic regression models of diabetes, sCD36 showed only a weak association with T2D. The current findings show a weak association of circulating sCD36 with type 2 diabetes and no association with T1D.

Association of C2, a derivative of the radial artery pressure waveform, with new onset of type 2 diabetes mellitus: the MESA study

BACKGROUND

Although microvascular dysfunction is known to result from diabetes, it might also lead to diabetes. Lower values of C2, a derivative of the radial artery pressure waveform, indicate microvascular dysfunction and predict hypertension and cardiovascular disease (CVD). We studied the association of C2 with incident diabetes in subjects free of overt CVD.

METHODS

Among multi-ethnic participants (n = 5214), aged 45-84 years with no diabetes, C2 was derived from the radial artery pressure waveform. Incident diabetes (N = 651) was diagnosed as new fasting glucose ≥ 126 mg/dL or antidiabetic medicine over ~ 10 years. The relative incidence density (RID) for incident diabetes per standard deviation (SD) of C2 was studied during ~ 10 years follow-up using four levels of adjustment.

RESULTS

Mean C2 at baseline was 4.58 ± 2.85 mL/mmHg × 100. The RID for incident diabetes per SD of C2 was 0.90 (95% CI 0.82-0.99, P = 0.03). After adjustment for demographics plus body size, the corresponding RID was 0.81 (95% CI 0.73-0.89, P < 0.0001); body mass index (BMI) was the dominant covariate here. After adjustment for demographics plus cardiovascular risk factors, the RID was 0.98 (95% CI 0.89, 1.07, P = 0.63). After adjustment for all the parameters in the previous models, the RID was 0.87 (95% CI 0.78, 0.96, P = 0.006).

CONCLUSIONS

In a multi-ethnic sample free of overt CVD and diabetes at baseline, C2 predicted incident diabetes after adjustment for demographics, BMI and CVD risk factors. Differences in arterial blood pressure wave morphology may indicate a long-term risk trajectory for diabetes, independently of body size and the classical risk factors.

Elevated expression of ICAM-1 in synovium is associated with early inflammatory response for cartilage degeneration in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is increasingly being recognized as an independent risk factor for the onset and progression of osteoarthritis (OA). Extensive studies have focused on the contribution of obesity (excessive mechanical stress), comorbidity frequently found in T2DM, to cartilage destruction during OA development. However, a little is known about how diabetes-related inflammation may affect the local cartilage in a diabetic objective. In the present study, we were able to establish a T2DM rat model using a combination of a low dose of streptozotocin with high-fat and high-sugar diet. Although the cartilage integrity was comparable between the control and T2DM groups, the expression of matrix metalloproteinases-13 (MMP-13) was significantly upregulated in T2DM, indicating the initiation of an early cascade of cartilage degeneration. In parallel, an obvious alteration of subchondral bone remodeling (inhibition of bone formation) was observed, as evidenced by the reduction of osterix-expressing positive cells. Moreover, we demonstrated that the expression of intercellular adhesion molecule-1 (ICAM-1) in the serum and synovium of T2DM rats was elevated, accompanied by an increase of synovitis score. We also noticed that the number of F4/80-positive macrophage cells was significantly increased in the T2DM group. Mechanistically, the expression of ICAM-1 in fibroblast-like synoviocytes can be triggered by glucose and interleukin-1β, which are the two important factors within the joint of T2DM. Given that MMP-13 expression was significantly upregulated in the T2DM cartilage, and that ICAM-1-mediated filtration of macrophage was associated with synovitis, we propose that ICAM-1 is essential for triggering a vicious cycle of inflammation within the joint, which together subsequently drivers the cartilage degradation.

The DrugPattern tool for drug set enrichment analysis and its prediction for beneficial effects of oxLDL on type 2 diabetes

Enrichment analysis methods, e.g., gene set enrichment analysis, represent one class of important bioinformatical resources for mining patterns in biomedical datasets. However, tools for inferring patterns and rules of a list of drugs are limited. In this study, we developed a web-based tool, DrugPattern, for drug set enrichment analysis. We first collected and curated 7019 drug sets, including indications, adverse reactions, targets, pathways, etc. from public databases. For a list of interested drugs, DrugPattern then evaluates the significance of the enrichment of these drugs in each of the 7019 drug sets. To validate DrugPattern, we employed it for the prediction of the effects of oxidized low-density lipoprotein (oxLDL), a factor expected to be deleterious. We predicted that oxLDL has beneficial effects on some diseases, most of which were supported by evidence in the literature. Because DrugPattern predicted the potential beneficial effects of oxLDL in type 2 diabetes (T2D), animal experiments were then performed to further verify this prediction. As a result, the experimental evidences validated the DrugPattern prediction that oxLDL indeed has beneficial effects on T2D in the case of energy restriction. These data confirmed the prediction accuracy of our approach and revealed unexpected protective roles for oxLDL in various diseases. This study provides a tool to infer patterns and rules in biomedical datasets based on drug set enrichment analysis. DrugPattern is available at http://www.cuilab.cn/drugpattern.

Significant Association Between Low Mitochondrial DNA Content in Peripheral Blood Leukocytes and Ischemic Stroke

Background

Cumulative evidence has shown that low mitochondrial DNA (mtDNA) content is related to elevated oxidative stress and atherosclerosis, which play important roles in ischemic stroke. The objective of this study was to explore the association between mtDNA content in peripheral blood leukocytes and ischemic stroke.

Methods and Results

A total of 350 patients with first‐ever ischemic stroke and 350 healthy controls were recruited in this case‐control study. The mtDNA content in peripheral blood leukocytes was determined by quantitative real‐time polymerase chain reaction. The levels of oxidized glutathione, reduced glutathione, and 8‐hydroxy‐2′‐deoxyguanosine were measured by ELISA kits. Multivariate logistic regression models were used to analyze the relationship between mtDNA content in peripheral blood leukocytes and ischemic stroke. Our results show that mtDNA content of patients with ischemic stroke was notably lower compared with controls. A significant association was found between low mtDNA content and ischemic stroke. Furthermore, significant interactions were identified between low mtDNA and proven risk factors in patients with ischemic stroke. The levels of oxidized glutathione and 8‐hydroxy‐2′‐deoxyguanosine were significantly greater in patients with ischemic stroke compared with controls.

Conclusions

Our results demonstrate that low mtDNA content in peripheral blood leukocytes is associated with ischemic stroke. The relationship of low mtDNA content and ischemic stroke was particularly notable in individuals who had low mtDNA content combined with diabetes mellitus, metabolic syndrome, or cigarette smoking. Oxidative stress may be one of the contributory factors to decreased mtDNA content in patients with ischemic stroke.

Regulation of Macrophage Apoptosis and Atherosclerosis by Lipid-Induced PKCδ Isoform Activation

RATIONALE

Activation of monocytes/macrophages by hyperlipidemia associated with diabetes mellitus and obesity contributes to the development of atherosclerosis. PKCδ (protein kinase C δ) expression and activity in monocytes were increased by hyperlipidemia and diabetes mellitus with unknown consequences to atherosclerosis.

OBJECTIVE

To investigate the effect of PKCδ activation in macrophages on the severity of atherosclerosis.

METHODS AND RESULTS

PKCδ expression and activity were increased in Zucker diabetic rats. Mice with selective deletion of PKCδ in macrophages were generated by breeding PKCδ flox/flox mice with LyzM-Cre and ApoE^-/- mice (MPKCδKO/ApoE^-/- mice) and studied in atherogenic (AD) and high-fat diet (HFD). Mice fed AD and HFD exhibited hyperlipidemia, but only HFD-fed mice had insulin resistance and mild diabetes mellitus. Surprisingly, MPKCδKO/ApoE^-/- mice exhibited accelerated aortic atherosclerotic lesions by 2-fold versus ApoE^-/- mice on AD or HFD. Splenomegaly was observed in MPKCδKO/ApoE^-/- mice on AD and HFD but not on regular chow. Both the AD or HFD increased macrophage number in aortic plaques and spleen by 1.7- and 2-fold, respectively, in MPKCδKO/ApoE^-/- versus ApoE^-/- mice because of decreased apoptosis (62%) and increased proliferation (1.9-fold), and not because of uptake, with parallel increased expressions of inflammatory cytokines. Mechanisms for the increased macrophages in MPKCδKO/ApoE^-/- were associated with elevated phosphorylation levels of prosurvival cell-signaling proteins, Akt and FoxO3a, with reduction of proapoptotic protein Bim associated with PKCδ induced inhibition of P85/PI3K.

CONCLUSIONS

Accelerated development of atherosclerosis induced by insulin resistance and hyperlipidemia may be partially limited by PKCδ isoform activation in the monocytes, which decreased its number and inflammatory responses in the arterial wall.

Depression, daily stressors and inflammatory responses to high-fat meals: when stress overrides healthier food choices

Depression, stress and diet can all alter inflammation. This double-blind, randomized crossover study addressed the impact of daily stressors and a history of major depressive disorder (MDD) on inflammatory responses to high-fat meals. During two separate 9.5 h admissions, 58 healthy women (38 breast cancer survivors and 20 demographically similar controls), mean age 53.1 years, received either a high saturated fat meal or a high oleic sunflower oil meal. The Daily Inventory of Stressful Events assessed prior day stressors and the Structured Clinical Interview for DSM-IV evaluated MDD. As expected, for a woman with no prior day stressors, C-reactive protein (CRP), serum amyloid A (SAA), intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) were higher following the saturated fat meal than the high oleic sunflower oil meal after controlling for pre-meal measures, age, trunk fat and physical activity. But if a woman had prior day stressors, these meal-related differences disappeared-because the stressors heightened CRP, SAA, sICAM-1 and sVCAM-1 responses to the sunflower oil meal, making it look more like the responses to the saturated fat meal. In addition, women with an MDD history had higher post-meal blood pressure responses than those without a similar history. These data show how recent stressors and an MDD history can reverberate through metabolic alterations, promoting inflammatory and atherogenic responses.

Circulating cellular adhesion molecules and risk of diabetes: the Multi-Ethnic Study of Atherosclerosis (MESA)

AIMS

To test the hypothesis that soluble cellular adhesion molecules would be positively and independently associated with risk of diabetes.

METHODS

Soluble levels of six cellular adhesion molecules (ICAM-1, E-selectin, VCAM-1, E-cadherin, L-selectin and P-selectin) were measured in participants in the Multi-Ethnic Study of Atherosclerosis, a prospective cohort study. Participants were then followed for up to 10 years to ascertain incident diabetes.

RESULTS

Sample sizes ranged from 826 to 2185. After adjusting for age, sex, race/ethnicity, BMI and fasting glucose or HbA1c , four cellular adhesion molecules (ICAM-1, E-selectin, VCAM-1 and E-cadherin) were positively associated with incident diabetes and there was a statistically significant trend across quartiles. Comparing the incidence of diabetes in the highest and lowest quartiles of each cellular adhesion molecule, the magnitude of association was largest for E-selectin (hazard ratio 2.49; 95% CI 1.26-4.93) and ICAM-1 (hazard ratio 1.76; 95% CI 1.22-2.55) in fully adjusted models. Tests of effect modification by racial/ethnic group and sex were not statistically significant for any of the cellular adhesion molecules (P > 0.05).

CONCLUSIONS

The finding of significant associations between multiple cellular adhesion molecules and incident diabetes may lend further support to the hypothesis that microvascular endothelial dysfunction contributes to risk of diabetes.

Oxidative stress, inflammation, endothelial dysfunction and incidence of type 2 diabetes

BACKGROUND

Oxidative stress, inflammation and endothelial dysfunction are interrelated factors in the etiology of cardiovascular disease, but their linkage to type 2 diabetes is less clear. We examined the association of these biomarkers with incident type 2 diabetes (T2D).

METHODS

Analysis of 2339 participants in the community-based coronary artery risk development in young adults (CARDIA) study. Participants (age 40.1 ± 3.6 years, 44 % Black, 58 % women) were free of diabetes, and were followed 10 years. Cox regression was used to estimate hazard ratios (HRs) for incident T2D adjusting for the other biomarkers under study, demographic and lifestyle measures, dietary biomarkers, BMI (kg/m(2)) and metabolic syndrome components.

RESULTS

F2-isoprostanes and oxidized LDL (oxidative stress) were positively associated with incident T2D, but the associations were attenuated by adjustment for BMI. C-reactive protein was positively associated with T2D even with full adjustment: HR (95 % CI) = 2.21 (1.26-3.88) for quartile 4 (Q4) v. quartile 1 (Q1). The HR (95 % CI) for T2D for biomarkers of endothelial dysfunction ICAM-1 and E-selectin for Q4 v. Q1 were 1.64 (0.96-2.81) and 1.68 (1.04-2.71) respectively, with full adjustment. Including these two markers in a common risk score incorporating BMI and clinical measures improved the prediction probability of T2D: relative risk for the average person classified up compared to the average person classified down: 1.09, (1.06-1.13), P < 0.0001.

CONCLUSIONS

Biomarkers of inflammation and endothelial dysfunction were positively associated with incident T2D. ICAM-1 and E-selectin add to the prediction of T2D beyond a common risk score.

Palmitate-stimulated monocytes induce adhesion molecule expression in endothelial cells via IL-1 signaling pathway

Increased intake of saturated fatty acids (SFAs), such as palmitate (Pal), is linked to a higher risk of type 2 diabetes and cardiovascular disease. Although recent studies have investigated the direct effects of SFAs on inflammatory responses in vascular endothelial cells, it remains unknown whether SFAs also induce these responses mediated by circulating cells. In this study, especially focused on adhesion molecules and monocytes, we investigated the indirect effects of Pal on expression and release of ICAM-1 and E-selectin in vascular endothelial cells. Phorbol 12-myristate 13-acetate (PMA)-treated THP-1 (pTHP-1) cells and human monocytes were stimulated with various free fatty acids (FFAs). SFAs, but not unsaturated fatty acids (UFAs), increased interleukin (IL)-1β secretion and decreased IL-1 receptor antagonist (IL-1Ra) secretion, resulting in an increase in the IL-1β/IL-1Ra secretion ratio. UFAs dose-dependently inhibited the increase in IL-1β secretion and decrease in IL-1Ra secretion induced by Pal. Moreover, in human aortic and vein endothelial cells, expression and release of ICAM-1 and E-selectin were induced by treatment with conditioned medium collected from Pal-stimulated pTHP-1 cells and human monocytes, but not by Pal itself. The up-regulated expression and release of adhesion molecules by the conditioned medium were mostly abolished by recombinant human IL-1Ra supplementation. These results suggest that the Pal-induced increase in the ratio of IL-1β/IL-1Ra secretion in monocytes up-regulates endothelial adhesion molecules, which could enhance leukocyte adhesion to endothelium. This study provides further evidence that IL-1β neutralization through receptor antagonism may be useful for preventing the onset and development of cardiovascular disease.

Asymmetric dimethylarginine predicts decline of glucose tolerance in men with stable coronary artery disease: a 4.5-year follow-up study

Background

Endothelial dysfunction, largely dependent on impaired nitric oxide bioavailability, has been reportedly associated with incident type 2 diabetes. Our aim was to test the hypothesis that asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide formation, might be linked to future deterioration in glucose tolerance in stable coronary artery disease (CAD).

Methods

We studied 80 non-diabetic men (mean age 55 ± 11 years) with stable angina who underwent successful elective complex coronary angioplasty and were receiving a standard medication according to practice guidelines. Plasma ADMA and its structural isomer symmetric dimethylarginine (SDMA) were measured prior to coronary angiography. An estimate of insulin resistance by homeostasis model assessment (HOMA-IR index) was calculated from fasting insulin and glucose. Deterioration in glucose tolerance was defined as development of type 2 diabetes or progression from a normal glucose tolerance to impaired fasting glucose.

Results

Over a median follow-up of 55 months 11 subjects developed type 2 diabetes and 13 progressed to impaired fasting glucose. Incident deterioration of glucose tolerance was associated with ADMA (hazard ratio [HR] per 1-SD increment 1.64 [95% CI: 1.14–2.35]; P = 0.007), log (HOMA-IR index) (HR = 1.60 [1.16–2.20]; P = 0.004) and body-mass index (HR = 1.44 [0.95–2.17]; P = 0.08) by univariate Cox regression. ADMA (HR = 1.65 [1.14–2.38]; p = 0.008) and log (HOMA-IR index) (HR = 1.55 [1.10–2.17]; P = 0.01) were multivariate predictors of a decline in glucose tolerance. ADMA and SDMA were unrelated to body-mass index, HOMA-IR index, insulin or glucose.

Conclusions

ADMA predicts future deterioration of glucose tolerance independently of baseline insulin resistance in men with stable CAD. Whether this association reflects a contribution of endothelial dysfunction to accelerated decline of insulin sensitivity, or represents only an epiphenomenon accompanying pre-diabetes, remains to be elucidated. The observed relationship might contribute to the well-recognized ability of ADMA to predict cardiovascular outcome.

Immune mechanisms in atherosclerosis, especially in diabetes type 2

Atherosclerosis and ensuing cardiovascular disease (CVD) are major complications of diabetes type 2. Atherosclerosis is a chronic inflammatory condition involving immunocompetent cells of different types present in the lesions. Even though inflammation and immune activation may be more pronounced in atherosclerosis in diabetes type 2, there does not appear to be any major differences between diabetics and non-diabetics. Similar factors are thus implicated in atherosclerosis-associated immune activation in both groups. The cause of immune activation is not known and different mutually non-exclusive possibilities exist. Oxidized and/or enzymatically modified forms of low-density lipoprotein (OxLDL) and dead cells are present in atherosclerotic plaques. OxLDL could play a role, being pro-inflammatory and immunostimulatory as it activates T-cells and is cytotoxic at higher concentrations. Inflammatory phospholipids in OxLDL are implicated, with phosphorylcholine (PC) as one of the exposed antigens. Antibodies against PC (anti-PC) are anti-atherogenic in mouse studies, and anti-PC is negatively associated with development of atherosclerosis and CVD in humans. Bacteria and virus have been discussed as potential causes of immune activation, but it has been difficult to find direct evidence supporting this hypothesis, and antibiotic trials in humans have been negative or inconclusive. Heat shock proteins (HSP) could be one major target for atherogenic immune reactions. More direct causes of plaque rupture include cytokines such as interleukin 1β (IL-1β), tumor necrosis factor (TNF), and also lipid mediators as leukotrienes. In addition, in diabetes, hyperglycemia and oxidative stress appear to accelerate the development of atherosclerosis, one mechanism could be via promotion of immune reactions. To prove that immune reactions are causative of atherosclerosis and CVD, further studies with immune-modulatory treatments are needed.

In vivo transcriptomic profile after a Mediterranean diet in high-cardiovascular risk patients: a randomized controlled trial

BACKGROUND

Nutrients can exert healthy effects through nutrigenomic modulation. Data are scarce concerning the in vivo effect of a sustained traditional Mediterranean diet (TMD) pattern on the whole transcriptomic response.

OBJECTIVE

We explored the overall nutrigenomic effect associated with a TMD.

DESIGN

We focused on biological pathways related to cardiovascular disease (CVD) in a subsample (n = 34) of the Prevención Con Dieta Mediterránea (PREDIMED) study, which was a large, parallel-group, multicenter, randomized controlled trial that aimed to assess the effects of TMD on the primary prevention of CVD in individuals with high cardiovascular risk. Participants were randomly assigned to a low-fat diet control group or TMD intervention groups [traditional Mediterranean diet supplemented with virgin olive oil (TMD+VOO) or traditional Mediterranean diet supplemented with nuts (TMD+Nuts)] in equal proportions. Three-month changes in whole genome peripheral blood mononuclear cells were assessed by using whole transcriptome microarray analyses.

RESULTS

A functional annotation analysis was performed on 241 selected responder genes after the TMD+VOO (139 upregulated and 102 downregulated genes), 312 selected responder genes after the TMD+Nuts (165 upregulated and 147 downregulated genes), and 145 selected responder genes after the low-fat (100 upregulated and 45 downregulated genes) diets. Of 18 cardiovascular canonical pathway analyses, 12 pathways were differentially expressed, and 43% of pathways were modulated by both TMDs; the most prevalent pathways were related to atherosclerosis and hypertension. After simultaneous testing adjustment, 9 pathways were modulated by the TMD+VOO diet, and 4 pathways were modulated by the TMD+Nuts diet.

CONCLUSION

One of the mechanisms by which TMD, particularly if supplemented with virgin olive oil, can exert health benefits is through changes in the transcriptomic response of genes related to cardiovascular risk. This trial was registered at the London-based Current Controlled Trials register as ISRCTN35739639.

Impact of the LDL subfraction phenotype on Lp-PLA2 distribution, LDL modification and HDL composition in type 2 diabetes

Background

Qualitative alterations of lipoproteins underlie the high incidence of atherosclerosis in diabetes. The objective of this study was to assess the impact of low-density lipoprotein (LDL) subfraction phenotype on the qualitative characteristics of LDL and high-density lipoprotein (HDL) in patients with type 2 diabetes.

Methods

One hundred twenty two patients with type 2 diabetes in poor glycemic control and 54 healthy subjects were included in the study. Patients were classified according to their LDL subfraction phenotype. Seventy-seven patients presented phenotype A whereas 45 had phenotype B. All control subjects showed phenotype A. Several forms of modified LDL, HDL composition and the activity and distribution of lipoprotein-associated phospholipase A2 (Lp-PLA2) were analyzed.

Results

Oxidized LDL, glycated LDL and electronegative LDL were increased in both groups of patients compared with the control group. Patients with phenotype B had increased oxidized LDL and glycated LDL concentration than patients with phenotype A. HDL composition was abnormal in patients with diabetes, being these abnormalities more marked in patients with phenotype B. Total Lp-PLA2 activity was higher in phenotype B than in phenotype A or in control subjects. The distribution of Lp-PLA2 between HDL and apoB-containing lipoproteins differed in patients with phenotype A and phenotype B, with higher activity associated to apoB-containing lipoproteins in the latter.

Conclusions

The presence of LDL subfraction phenotype B is associated with increased oxidized LDL, glycated LDL and Lp-PLA2 activity associated to apoB-containing lipoproteins, as well as with abnormal HDL composition.

Chronic inflammation role in the obesity-diabetes association: a case-cohort study

BACKGROUND

Chronic inflammation is related to both obesity and diabetes. Our aim was to investigate to what extent this inflammation contributes to the association between obesity and diabetes.

METHODS

Using a case-cohort design, we followed 567 middle-aged individuals who developed diabetes and 554 who did not over 9 years within the ARIC Study. Weighted Cox proportional hazards analyses permitted statistical inference to the entire cohort.

RESULTS

Obese individuals (BMI≥30 kg/m2), compared to those with BMI<25 kg/m2, presented a large increased risk of developing diabetes (HR[obesity]=6.4, 95%CI 4.5-9.2), as did those in the highest (compared to the lowest) quartile of waist circumference (HR[waist]=8.3, 95%CI 5.6-12.3), in analyses adjusted for age, gender, ethnicity, study center, and parental history of diabetes. Notably, further adjustment for adiponectin and inflammation markers halved the magnitude of these associations (HR[obesity]=3.2, 95%CI 2.1-4.7; and HR[waist]=4.2, 95%CI 2.8-6.5). In similar modeling, attenuation obtained by adding fasting insulin, instead of these markers, was only slightly more pronounced HR[obesity]=2.7, 95%CI 1.7-4.1; and HR[waist]=3.6, 95%CI 2.3-5.8).

CONCLUSIONS

The marked decrease in the obesity-diabetes association after taking into account inflammation markers and adipokines indicates their major role in the pathways leading to adult onset of diabetes in obese individuals.

High levels of iron status and oxidative stress in patients with metabolic syndrome

Studies concerning oxidative stress (OxE) parameters have increased, mainly because of its important role in cardiovascular diseases and diabetes complications. The main objective of this study was to evaluate iron nutrition status and oxidative stress parameters in subjects that had developed metabolic syndrome (MetS). Subjects from the Research Program of Risk Factors for Cardiovascular Disease (n = 155) were studied (ages ranging from 45 to 65 years old) and classified according to the Adult Treatment Panel III criterion. A blood sample was taken after a 12-h fasting period, and basal glucose, insulin, thiobarbituric acid reactive substances (TBARS), oxidized LDL (oxLDL), heme oxygenase (HO) activity, lipid profile, and iron nutrition status were determined. Eighty-five subjects were classified as MetS, and 70 non-MetS. Individuals with MetS showed higher Fe storage (high levels of ferritin, total body iron and low transferrin receptor), oxLDL, TBARS, and homeostatic model assessment for insulin resistance levels. The MetS group showed high levels of oxidative stress parameters (HO activity, oxLDL, and TBARS). The presence of MetS showed an association with LDL oxidation risk (multiple lineal regression according to sex and age, p < 0.001). High levels of triglycerides (p < 0.001) and waist circumference (p < 0.012) were associated with oxLDL levels, as well as an association between TBARS and oxLDL with ferritin levels. Through logistic regression analyses, the highest quartile of ferritin was associated with a threefold risk of developing MetS compared to the lowest quartile; also, TBARS showed a 21-fold risk for the development of MetS. Finally, elevated levels of oxidative stress parameters such us oxLDL, TBARS, HO, and Fe storage were associated to MetS.

The impact of rapid weight loss on oxidative stress markers and the expression of the metabolic syndrome in obese individuals

OBJECTIVE

Obesity is linked with a state of increased oxidative stress, which plays an important role in the etiology of atherosclerosis and type 2 diabetes mellitus. The aim of our study was to evaluate the effect of rapid weight loss on oxidative stress markers in obese individuals with metabolic syndrome (MetS).

DESIGN AND METHODS

We measured oxidative stress markers in 40 obese subjects with metabolic syndrome (MetS+), 40 obese subjects without metabolic syndrome (MetS-), and 20 lean controls (LC) at baseline and after three months of very low caloric diet.

RESULTS

Oxidized low density lipoprotein (ox-LDL) levels decreased by 12% in MetS+ subjects, associated with a reduction in total cholesterol (TC), even after adjustment for age and sex. Lipoprotein associated phospholipase A₂ (Lp-PLA₂) activity decreased by 4.7% in MetS+ subjects, associated with a drop in LDL-cholesterol (LDL-C), TC, and insulin levels. Multivariate logistic regression analysis showed that a model including ox-LDL, LpPLA₂ activity, and myeloperoxidase (MPO) improved prediction of MetS status among obese individuals compared to each oxidative stress marker alone.

CONCLUSIONS

Oxidative stress markers were predictive of MetS in obese subjects, suggesting a higher oxidative stress. Rapid weight loss resulted in a decline in oxidative stress markers, especially in MetS+ patients.

Novel risk factors and the prediction of type 2 diabetes in the Atherosclerosis Risk in Communities (ARIC) study

OBJECTIVE

The objective of this study was to determine potential added value of novel risk factors in predicting the development of type 2 diabetes beyond that provided by standard clinical risk factors.

RESEARCH DESIGN AND METHODS

The Atherosclerosis Risk in Communities (ARIC) Study is a population-based prospective cohort study in four U.S. communities. Novel risk factors were either measured in the full cohort or in a case-control sample nested within the cohort. We started with a basic prediction model, previously validated in ARIC, and evaluated 35 novel risk factors by adding them independently to the basic model. The area under the curve (AUC), net reclassification index (NRI), and integrated discrimination index (IDI) were calculated to determine if each of the novel risk factors improved risk prediction.

RESULTS

There were 1,457 incident cases of diabetes with a mean of >7.6 years of follow-up among 12,277 participants at risk. None of the novel risk factors significantly improved the AUC. Forced expiratory volume in 1 s was the only novel risk factor that resulted in a significant NRI (0.54%; 95% CI: 0.33-0.86%). Adiponectin, leptin, γ-glutamyl transferase, ferritin, intercellular adhesion molecule 1, complement C3, white blood cell count, albumin, activated partial thromboplastin time, factor VIII, magnesium, hip circumference, heart rate, and a genetic risk score each significantly improved the IDI, but net changes were small.

CONCLUSIONS

Evaluation of a large panel of novel risk factors for type 2 diabetes indicated only small improvements in risk prediction, which are unlikely to meaningfully alter clinical risk reclassification or discrimination strategies.

Investigating endothelial activation and oxidative stress in relation to glycaemic control in a multiethnic population

AIM

An exploration of ethnic differences in measures of oxidative stress and endothelial activation in relation to known cardiovascular risk factors within South Asians (SA) and White Europeans (WE) residing in the UK.

METHODS

202 participants within a UK multiethnic population provided biomedical and anthropometric data. Human urinary 2,3-dinor-8-iso-prostaglandin-F1α and plasma ICAM-1 were quantified as measures of oxidative stress and endothelial activation, respectively.

RESULTS

2,3-Dinor-8-iso-prostaglandin-F1α levels were significantly higher in the SA group compared to WE group (10.36 (95% CI: 9.09, 11.79) versus 8.46 (7.71, 9.29), P = 0.021) after adjustment for age, gender, smoking status, body weight, HbA1c, and medication. Oxidative stress was positively associated with HbA1c (β = 1.08, 95% CI:1.02, 1.14, P = 0.009), fasting (β = 1.06, 95% CI: 1.02, 1.10, P = 0.002), and 2 hr glucose (β = 1.02, 95% CI: 1.00, 1.04, P = 0.052). In each adjusted model, SA continued to have elevated levels of oxidative stress compared to WE. ICAM-1 levels were significantly higher in the composite IGR group compared to the normoglycaemic group (P < 0.001). No ethnic differences in ICAM-1 were observed.

CONCLUSION

These results suggest that SA are more susceptible to the detrimental effects of hyperglycaemia-induced oxidative stress at lower blood glucose thresholds than WE. Further research into the potential mechanisms involved is warranted.

Microvascular dysfunction is associated with a higher incidence of type 2 diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

Recent data support the hypothesis that microvascular dysfunction may be a potential mechanism in the development of insulin resistance. We examined the association of microvascular dysfunction with incident type 2 diabetes mellitus (T2DM) and impaired glucose metabolism by reviewing the literature and conducting a meta-analysis of longitudinal studies on this topic.

METHODS AND RESULTS

We searched Medline and Embase for articles published up to October 2011. Prospective cohort studies that focused on microvascular measurements in participants free of T2DM at baseline were included. Pooled relative risks were calculated using random effects models. Thirteen studies met the inclusion criteria for this meta-analysis. These studies focused on T2DM or impaired fasting glucose, not on impaired glucose tolerance. The pooled relative risks for incident T2DM (3846 cases) was 1.25 (95% confidence interval, 1.15; 1.36) per 1 SD greater microvascular dysfunction when all estimates of microvascular dysfunction were combined. In analyses of single estimates of microvascular dysfunction, the pooled relative risks for incident T2DM was 1.49 (1.36; 1.64) per 1 SD higher plasma soluble E-selectin levels; 1.21(1.11; 1.31) per 1 SD higher plasma soluble intercellular adhesion molecule-1 levels; 1.48 (1.03; 2.12) per 1 SD lower response to acetylcholine-mediated peripheral vascular reactivity; 1.18 (1.08; 1.29) per 1 SD lower retinal arteriole-to-venule ratio; and 1.43 (1.33; 1.54) per 1 logarithmically transformed unit higher albumin-to-creatinine ratio. In addition, the pooled relative risks for incident impaired fasting glucose (409 cases) was 1.15 (1.01-1.31) per 1 SD greater retinal venular diameters.

CONCLUSIONS

These data indicate that various estimates of microvascular dysfunction were associated with incident T2DM and, possibly, impaired fasting glucose, suggesting a role for the microcirculation in the pathogenesis of T2DM.

Amelioration of lipid abnormalities by α-lipoic acid through antioxidative and anti-inflammatory effects

Recent data have revealed that oxidative products and inflammatory mediators are increased in the insulin-resistant states of obesity and type 2 diabetes mellitus (T2DM). Obese patients with impaired glucose tolerance (IGT) are at high risk for developing T2DM and have high incidence of dyslipidemia. α-Lipoic acid (ALA) is a potent antioxidant with insulin sensitizing activity. However, it is not clear whether ALA is effective on lipid parameters in humans. This study has investigated 22 obese subjects with IGT (obese-IGT), 13 of whom underwent 2-week ALA treatment, 600 mg intravenously once daily. Before and after the treatment, euglycemic-hyperinsulinemic clamps were used to measure insulin sensitivity. Meanwhile, plasma lipids, oxidative products, and chronic inflammatory markers were measured. After treatment of ALA in obese-IGT patients, insulin sensitivity was improved, insulin sensitivity index (ISI) impressively enhanced by 41%. Plasma levels of free fatty acids (FFAs), triglyceride (TG), total cholesterol (T-Chol), low density lipoprotein-cholesterol (LDL-Chol), small dense LDL-Chol (sd-LDL), oxidized LDL-Chol (ox-LDL-Chol), very low density lipoprotein-cholesterol (VLDL-Chol) were all significantly decreased (P < 0.01). At the same time, both plasma oxidative products (malondialdehyde (MDA), 8-iso-prostaglandin) and inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6)) were remarkably decreased (P < 0.01), while adiponectin was increased (P < 0.01). There are significant negative correlations between ISI and plasma FFAs, sd-LDL-Chol, ox-LDL-Chol, MDA, 8-iso-prostaglandin, TNF-α, and IL-6, and positive correlations with HDL-Chol and adiponectin in obese-IGT patients. The results indicate that short-term treatment with ALA can improve insulin sensitivity and plasma lipid profile possibly through amelioration of oxidative stress and chronic inflammatory reaction in obese patients with IGT.

Circulating oxidized LDL and inflammation in extreme pediatric obesity

Oxidative stress and inflammation have not been well-characterized in extreme pediatric obesity. We compared levels of circulating oxidized low-density lipoprotein (oxLDL), C-reactive protein (CRP), and interleukin-6 (IL-6) in extremely obese (EO) children to normal weight (NW) and overweight/obese (OW/OB) children. OxLDL, CRP, IL-6, BMI, blood pressure, and fasting glucose, insulin, and lipids were obtained in 225 children and adolescents (age 13.5 ± 2.5 years; boys 55%). Participants were classified into three groups based on gender- and age-specific BMI percentile: NW (<85th, n = 127), OW/OB (85th- <1.2 times the 95th percentile, n = 64) and EO (≥1.2 times the 95th percentile or BMI ≥35 kg/m(2), n = 34). Measures were compared across groups using analysis of covariance, adjusted for gender, age, and race. Blood pressure, insulin, and lipids worsened across BMI groups (all P < 0.0001). OxLDL (NW: 40.8 ± 9.0 U/l, OW/OB: 45.7 ± 12.1 U/l, EO: 63.5 ± 13.8 U/l) and CRP (NW: 0.5 ± 1.0 mg/l, OW/OB: 1.4 ± 2.9 mg/l, EO: 5.6 ± 4.9 mg/l) increased significantly across BMI groups (all groups differed with P < 0.01). IL-6 was significantly higher in EO (2.0 ± 0.9 pg/ml) compared to OW/OB (1.3 ± 1.2 pg/ml, P < 0.001) and NW (1.1 ± 1.0 pg/ml, P < 0.0001) but was not different between NW and OW/OB. Extreme pediatric obesity, compared to milder forms of adiposity and NW, is associated with higher levels of oxidative stress and inflammation, suggesting that markers of early cardiovascular disease and type 2 diabetes mellitus are already present in this young population.

Association between oxidized LDL, obesity and type 2 diabetes in a population-based cohort, the Health, Aging and Body Composition Study

BACKGROUND

Accumulating evidence suggests a cross-sectional association between oxidative stress and type 2 diabetes (T2D). Systemic oxidative stress, as measured by oxidized LDL (oxLDL), has been correlated with visceral fat. We examined the relationship between oxLDL, and T2D- and obesity-related traits in a bi-racial sample of 2985 subjects at baseline and after 7 years of follow-up.

METHODS

We examined six T2D-related traits (T2D status, HbA(1c), fasting glucose, insulin, adiponectin and HOMA-IR) as well as six obesity-related traits (obesity status, BMI, leptin, % body fat, visceral and subcutaneous fat mass) using logistic and linear regression models.

RESULTS

In all subjects at baseline, oxLDL was positively associated with T2D (OR = 1.3, 95% CI:1.1-1.5), fasting glucose (ss = 0.03 +/- 0.006), HbA(1c) (ss = 0.02 +/- 0.004), fasting insulin (ss = 0.12 +/- 0.02), HOMA-IR (ss = 0.13 +/- 0.02) and negatively with adiponectin (ss = -0.16 +/- 0.03), (all p < 0.001). The strength and magnitude of these associations did not differ much between blacks and whites. In both blacks and whites, oxLDL was also associated with obesity (OR = 1.3, 95% CI:1.1-1.4) and three of its related traits (ss = 0.60 +/- 0.14 for BMI, ss = 0.74 +/- 0.17 for % body fat, ss = 0.29 +/- 0.06 for visceral fat; all p < 0.001). Furthermore, of four traits measured after 7 years of follow-up (fasting glucose, HbA1c, BMI and % fat), their relationship with oxLDL was similar to baseline observations. No significant association was found between oxLDL and incident T2D. Interestingly, oxLDL was significantly associated with % change in T2D- and obesity-related traits in whites but not in blacks.

CONCLUSION/INTERPRETATION

Our data suggest that systemic oxidative stress may be a novel risk factor for T2D and obesity.

Lipoprotein metabolism mediates the association of MTP polymorphism with beta-cell dysfunction in healthy subjects and in nondiabetic normolipidemic patients with nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) predicts incident diabetes independently of insulin resistance, adiposity and metabolic syndrome through unclear mechanisms. Dietary fat consumption and lipoperoxidative stress predispose to diabetes in the general population and to liver injury in NASH. Microsomal triglyceride transfer protein (MTP) polymorphism modulates lipoprotein metabolism in the general population and liver disease in NASH; a functional MTP polymorphism recently predicted incident diabetes independently of insulin resistance in the general population. We simultaneously assessed the impact of MTP polymorphism, diet, adipokines and lipoprotein metabolism, on glucose homeostasis in NASH. MTP -493G/T polymorphism, dietary habits, adipokines and postprandial triglyceride-rich lipoproteins, high-density lipoprotein cholesterol (HDL-C) and oxidized low-density lipoprotein (oxLDL) responses to an oral fat load, were cross-sectionally correlated to oral glucose tolerance test- and frequently sampled intravenous glucose tolerance test-derived Minimal Model indexes of glucose homeostasis in 40 nondiabetic normolipidemic patients with NASH and 40 age-,sex- and body mass index-matched healthy controls. Despite comparable insulin resistance, fasting lipids, adipokines and dietary habits, MTP GG genotype had significantly more severe beta-cell dysfunction; higher plasma Tg, FFA, intestinal and hepatic very low-density lipoprotein 1 subfractions and oxLDL responses and deeper HDL-C fall than GT/TT carriers in patients and controls. Postprandial HDL-C and oxLDL responses independently predicted beta-cell dysfunction and mediated the effect of MTP polymorphism on beta-cell function. In nondiabetic normolipidemic NASH, MTP -493G/T polymorphism modulates beta-cell function, an effect mediated by postprandial HDL-C and oxLDL metabolism. The impact of this polymorphism on the risk of diabetes and the efficacy of lipid-lowering therapies in restoring beta-cell function in NASH, even with normal fasting lipid values, warrant further investigation.

Uric acid and insulin sensitivity and risk of incident hypertension

BACKGROUND

Uric acid, insulin sensitivity, and endothelial dysfunction may be important in the development of hypertension. Corresponding circulating biomarkers are associated with risk of hypertension, but because these factors may be interrelated, whether they independently affect risk is unknown.

METHODS

In 1496 women aged 32 to 52 years without hypertension at baseline, we prospectively analyzed the associations between fasting plasma levels of uric acid, insulin, triglycerides, the insulin sensitivity index, and 2 biomarkers associated with endothelial dysfunction (homocysteine and soluble intercellular adhesion molecule-1) and the odds of incident hypertension. Odds ratios were adjusted for standard risk factors and then for all biomarkers plus estimated glomerular filtration rate and total cholesterol level. Population-attributable risk was estimated for biomarkers significantly associated with hypertension.

RESULTS

All the biomarkers were associated with incident hypertension after adjustment for standard hypertension risk factors. However, after simultaneously controlling for all the biomarkers, estimated glomerular filtration rate, and total cholesterol level, only uric acid and insulin levels were independently associated with incident hypertension. Comparing the highest and lowest quartiles of uric acid levels, the odds ratio was 1.89 (95% confidence interval, 1.26-2.82). A similar comparison yielded an odds ratio of 2.03 (95% confidence interval, 1.35-3.05) for insulin levels. Using an estimated basal incidence rate of 14.6 per 1000 annually, 30.8% of all hypertension occurring in young women annually is associated with uric acid levels of 3.4 mg/dL or greater (to convert to micromoles per liter, multiply by 59.485). For insulin levels of 2.9 microIU/mL or greater (to convert to picomoles per liter, multiply by 6.945), this proportion is 24.2%.

CONCLUSIONS

Differences in uric acid and insulin levels robustly and substantially affect the risk of hypertension in young women. Measuring these biomarkers in clinical practice may identify higher-risk individuals.

Fasting and postprandial glycoxidative and lipoxidative stress are increased in women with type 2 diabetes

OBJECTIVE

We studied acute changes in markers of glycoxidative and lipoxidative stress, including oxidized LDL, N(epsilon)-(carboxyethyl)-lysine (CEL), N(epsilon)-(carboxymethyl)-lysine (CML), and 3-deoxyglucosone (3DG), following two consecutive meals.

RESEARCH DESIGN AND METHODS

Postmenopausal women (27 with normal glucose metabolism [NGM], 26 with type 2 diabetes) received two consecutive fat-rich meals and two consecutive carbohydrate-rich meals on two occasions. Glucose and triglyceride concentrations were measured at baseline and 1, 2, 4, 6, and 8 h following breakfast; lunch was given at 4 h. Oxidized LDL-to-LDL cholesterol ratio, CEL, CML, and 3DG were measured at baseline and at 8 h.

RESULTS

Fasting oxidized LDL-to-LDL cholesterol ratio, 3DG, and CML were higher in women with type 2 diabetes compared with women with NGM and were comparable to the postprandial values at 8 h in NGM. Postprandial rises in the oxidized LDL-to-LDL cholesterol ratio and 3DG were similar in both groups. However, the oxidized LDL-to-LDL cholesterol ratio increased more after the fat-rich meals, whereas CML and 3DG increased more after the carbohydrate-rich meals. After the fat-rich meals, the increase in the oxidized LDL-to-LDL cholesterol ratio correlated with postprandial triglycerides, whereas the increase in 3DG was correlated with postprandial glucose.

CONCLUSIONS

The acute changes in markers of glycoxidative and lipoxidative stress in both type 2 diabetes and NGM suggest that postabsorptive oxidative stress may partly underlie the association of postprandial derangements and cardiovascular risk.