Showing papers by "Sridevi Devaraj published in 2010"

Increased Toll-Like Receptor (TLR) Activation and TLR Ligands in Recently Diagnosed Type 2 Diabetic Subjects

Abstract: OBJECTIVE Individuals with type 2 diabetes have a myriad of metabolic aberrations including increased inflammation, increasing their cardiovascular risk. Toll-like receptors (TLRs) and their ligands play a key role in insulin resistance and atherosclerosis. However, there is a paucity of data examining the expression and activity of TLRs in type 2 diabetes. Thus, in the present study, we examined TLR2 and TLR4 mRNA and protein expression, their ligands, and signaling in monocytes of recently diagnosed type 2 diabetic patients. RESEARCH DESIGN AND METHODS TLR mRNA, protein expression, TLR ligands, and TLR signaling were measured in freshly isolated monocytes from healthy human control subjects ( n = 23) and type 2 diabetic subjects ( n = 23) using real-time RT-PCR, Western blot, and flow cytometric assays. RESULTS Type 2 diabetic subjects had significantly increased TLR2, TLR4 mRNA, and protein in monocytes compared with control subjects ( P < 0.05). Increased TLR2 and TLR4 expression correlated with BMI, homeostasis model assessment–insulin resistance (HOMA-IR), glucose, A1C, Ne-(carboxymethyl) lysine (CML), and free fatty acid (FFA). Ligands of TLR2 and TLR4, namely, HSP60, HSP70, HMGB1, endotoxin, and hyaluronan levels, were elevated in type 2 diabetic subjects and positively correlated with TLR2 and TLR4. Type 2 diabetic subjects showed increased MyD88, phosphorylated IRAK-1, Trif, TICAM-1, IRF-3, and NF-κB p65 expression in monocytes compared with control subjects. Furthermore, TLR-MyD88-NF-κB signaling resulted in elevated levels of cytokines ( P < 0.05), but increased interleukin (IL)-1β, interferon (IFN)-γ, and endotoxin were not significant when adjusted for BMI. CONCLUSIONS In this comprehensive study, we make the novel observation that TLR2 and TLR4 expression and their ligands, signaling, and functional activation are increased in recently diagnosed type 2 diabetes and contribute to the proinflammatory state.

Diabetes is a proinflammatory state: a translational perspective.

Abstract: The diabetic state confers an increased propensity to accelerated atherogenesis Inflammation is pivotal in atherosclerosis; in addition to the established risk factors, inflammation appears to play a pivotal role in diabetes and its complications Evidence for increased inflammation includes: increased levels of plasma C-reactive protein, the prototypic marker of inflammation; increased levels of plasminogen-activator inhibitor; increased monocyte superoxide and proinflammatory cytokine release (IL-1, IL-6 and TNF-α); increased monocyte adhesion to endothelium; increased NF-κB activity; and increased Toll-like receptor 2 and 4 expression and activity in diabetes Thus, it appears that both Type 1 and Type 2 diabetes are proinflammatory states and that these could contribute to increased diabetic vasculopathies

Role of C-Reactive Protein in Contributing to Increased Cardiovascular Risk in Metabolic Syndrome

Abstract: Metabolic syndrome is associated with increased propensity for diabetes and cardiovascular disease. Low-grade inflammation is characteristic of metabolic syndrome. C-reactive protein, the best characterized biomarker of inflammation, is also an independent predictor of future cardiovascular events. This review outlines the role of high-sensitivity C-reactive protein in contributing to increased cardiovascular risk in metabolic syndrome by inducing endothelial cell dysfunction and activating monocytes.

Effects of epigallocatechin gallate on regulatory T cell number and function in obese v. lean volunteers

Abstract: Obesity predisposes to an increased incidence of diabetes and CVD. Also, obesity is a pro-inflammatory state. Regulatory T cells (Tregs) are essential negative regulators of inflammation and are down-regulated in pro-inflammatory states. Animal models of obesity are associated with decreased Tregs. The dietary modulation of Tregs could be used as a therapeutic strategy to control inflammation. Epigallocatechin gallate (EGCG) is a potent anti-inflammatory agent and an active ingredient of green tea and is suggested to have a role as a preventive agent in obesity, diabetes and CVD. The role of EGCG in the modulation of Tregs has, however, not been studied. Thus, the aim of the present study was to determine the effect of EGCG on the number and function of Tregs in obese and lean human subjects in vitro, and to delineate its specific regulation mechanisms. Tregs were isolated from normal-weight and obese subjects. Tregs were cultured in the absence or presence of EGCG (20 mum) for 24 h. Foxp3-expressing Tregs were enumerated using flow cytometry. Histone deacetylase (HDAC) activity and nuclear NF-kappaBp65 level were measured by ELISA and Western blots. Obese subjects had lower Tregs and IL-10 production than lean subjects. EGCG treatment significantly enhanced the number of Foxp3-expressing Tregs and IL-10 production in vitro (P < 0.05) in both groups. Also, EGCG decreased NF-kappaB activity and increased HDAC activity and HDAC-2 expression in Tregs (P < 0.05) in both groups. Thus, in part, EGCG enhances the functionality of Tregs, i.e. IL-10 production and number by suppressing the NF-kappaB signalling pathway via inducing epigenetic changes.

Circulating Levels of Endothelial Progenitor Cell Mobilizing Factors in the Metabolic Syndrome

Abstract: Endothelial progenitor cells (EPCs) are an emerging biomarker of vascular health. However, there are few data on the biology and mobilizing factors of EPCs in metabolic syndrome (MS). The aim of this study was to assay EPC mobilizing factors, including granulocyte colony-stimulating factor, stem cell factor/c-kit ligand (SCF), vascular endothelial growth factor, and stromal cell–derived factor–1 levels, in patients with MS (n = 36) and age- and gender-matched controls (n = 38). There was a significant reduction of 83% in granulocyte colony-stimulating factor levels in patients with MS. Also, there were decreases in SCF and SCF soluble receptor levels. However, there was no significant difference in stromal cell–derived factor–1 levels, and paradoxically, vascular endothelial growth factor levels were increased, consistent with resistance. In conclusion, in addition to progenitor cell exhaustion as a mechanism for the decrease in EPCs in patients with MS, they also have a mobilization defect, as manifested by decreased levels of granulocyte colony-stimulating factor and SCF, resulting in a decrease in EPCs.

Effect of tocopheryl phosphate on key biomarkers of inflammation: Implication in the reduction of atherosclerosis progression in a hypercholesterolaemic rabbit model.

Abstract: 1. Many studies have evaluated the effectiveness of alpha-tocopherol (vitamin E) in the development and progression of cardiovascular diseases, with conflicting results reported on the protective effect of this anti-oxidant. 2. The present study examined the effectiveness of a novel tocopheryl phosphate mixture (TPm) compared with that of alpha-tocopherol (TA) on key pro-inflammatory markers involved in atherogenesis, including interleukin (IL)-1beta, IL-6, IL-8, plasminogen activator inhibitor-1, tumour necrosis factor-alpha and C-reactive protein (CRP), as well as vascular function and lesion development in rabbits fed a 2% cholesterol diet. 3. Treatment with TPm, incorporated into the rabbit food at four doses ranging from 60 to 360 mg/kg chow, resulted in a significant reduction in plasma levels of all pro-inflammatory cytokines and biomarkers that appeared to be somewhat dose dependent. Conversely, treatment with TA, at a dose equivalent to the highest dose of TPm used, only decreased plasma levels of CRP, IL-6 and IL-8. Both TPm and TA treatment significantly improved vascular function to a similar extent, although TPm was more effective in reducing lesion development. 4. The reduction in these key pro-inflammatory markers appears to follow the improvement in the atherogenic state of the animals, indicating that the anti-inflammatory properties of TPm may be potentially beneficial in inflammatory disease states.

Evaluation of a method for fibroblast growth factor-23: a novel biomarker of adverse outcomes in patients with renal disease.

Abstract: Background: Fibroblast growth factor 23 (FGF-23), a phosphaturic peptide hormone secreted by the osteoblasts, is an important regulator of phosphorus and vitamin D metabolism. In chronic kidney disease, FGF-23 levels rise with declining kidney function. Increasing FGF-23 levels are associated with increasing risk of mortality in dialysis patients. Two assays for FGF-23 have been reported. One assay detects only full-length/intact FGF-23. In contrast, the carboxy-terminal assay recognizes both intact and carboxy-terminal FGF-23. Aim/Methods: The aim of this study was to evaluate both assays for FGF-23. Test samples were analyzed with both the intact and carboxy-terminal FGF-23 enzyme-linked immunosorbent assay (ELISA) kits according to manufacturers' instructions. Results: Carboxy-terminal FGF-23 showed very good precision with coefficients of variation (CV) ranging from 4% to 10.5%, whereas the CVs for intact FGF-23 were not very good (6–37.5%). The carboxy-terminal assay was linear, stable in pl...

C-Reactive Protein Adversely Alters the Protein–Protein Interaction of the Endothelial Isoform of Nitric Oxide Synthase

Abstract: BACKGROUND: C-reactive protein (CRP) inhibits the activity of the endothelial isoform of nitric oxide synthase (eNOS) via uncoupling of the enzyme both in vitro and in vivo. eNOS activity appears to be related in part to its interaction with other cellular proteins, including heat shock protein 90 (Hsp90), caveolin-1, and porin. In this study, we examined the effect of CRP treatment of human aortic endothelial cells (HAECs) on eNOS interaction with caveolin-1, Hsp90, and porin. METHODS: We incubated HAECs with CRP (0, 12.5, and 25 mg/L) for 1, 6, or 24 h and assessed the interaction of these proteins with eNOS by immunoprecipitation and western blotting. RESULTS: CRP treatment (12.5 and 25 mg/L) of HAECs for 24 h significantly increased eNOS binding to caveolin-1 (40% and 54% increase, respectively; P < 0.05) and decreased binding to Hsp90 (33% and 66% decrease, respectively; P < 0.05). CRP (25 mg/L) also significantly decreased the binding of porin to eNOS (11% decrease, P < 0.05). Similar results were seen when HAECs were treated with CRP for 6 h. CONCLUSIONS: These negative protein–protein interactions of eNOS were able to partly explain the CRP-induced decreases in the activity of this critical enzyme, which caused endothelial dysfunction.

Crataegus oxycantha extract attenuates apoptotic incidence in myocardial ischemia-reperfusion injury by regulating Akt and HIF-1 signaling pathways.

Abstract: The objective of the present study was to evaluate the efficacy and mechanism of Crataegus oxycantha (COC) extract in preventing ischemia-reperfusion (IR) injury in an in vivo rat model of acute myocardial infarction induced by a 30-minute regional ischemia followed by 72 hours of reperfusion. The COC extract [100 mg/(kg body weight)] was administered 12 hours after the surgical procedure and then at 24-hour intervals for 3 days. Animals treated with COC extract showed a significant decrease in creatine kinase activity and infarct size. At the molecular level, COC administration resulted in a significant attenuation of PTEN (phosphatase and tensin homolog deleted on chromosome 10) and upregulation of phospho-Akt and c-Raf levels in the heart. As a consequence, cleaved caspase-9 and cleaved caspase-7 levels were significantly downregulated, indicating negative regulation of apoptosis by COC extract. In part with the hypoxia-inducible factor (HIF) signaling pathway, COC extract administration significantly upregulated the prolyl hydroxylase-2 level. In contrast, other proapoptotic proteins such as nuclear factor-κB, cytochrome c, apoptosis-inducing factor, and cleaved poly(adenosine diphosphate-ribose) polymerase levels were significantly downregulated in the COC-treated group when compared with the untreated control group. The results suggested that COC extract attenuated apoptotic incidence in the experimental myocardial ischemia-reperfusion model by regulating Akt and HIF-1 signaling pathways.

A randomized placebo-controlled crossover trial of aloe vera on bioavailability of vitamins C and B(12), blood glucose, and lipid profile in healthy human subjects.

Abstract: Several factors limit the absorption and bioavailability of vitamins. Vitamin C, a commonly used water-soluble supplement reduces the risk of disease. Vitamin B(12) is necessary for the development of RBC, growth, and nervous system. Vitamin B(12) deficiency is common among elderly. Thus, agents that improve bioavailability of vitamin C and B(12), especially in older individuals would be important. Aloe Vera is a botanical with immunomodulatory properties. Aloe is processed using the hand-filleted technique or whole leaf procedure. The aim of this study is to examine the effect of two different aloe vera preparations (aloe inner leaf gel, [AG] and aloe whole leaf decolorized gel, [AL]) compared to placebo on the bioavailability of vitamins, C and B(12), in healthy human volunteers in a randomized crossover trial. Subjects (n = 15) received in a random fashion either aloe whole leaf extract (AL with vitamins B(12), 1 mg and vitamin C 500 mg) or aloe fillet gel (AG with B(12) 1 mg and vitamin C 500 mg) or water (with vitamin B(12) 1 mg and vitamin C 500 mg). Blood was obtained fasting, followed by 1, 2, 4, 6, 8, and 24 hours postingestion of aloe/water. When given with vitamins C and B(12), AG significantly increased plasma oxygen radical absorbance capacity (ORAC) at both 4 and 24 hours and AL at 4 hours compared to baseline and placebo. AG significantly increased plasma vitamin C at 4, 6, 8, and 24 hours and AL at 4 and 6 hours compared to baseline and placebo (p <.01). Also, both aloes significantly increased serum vitamin B(12) levels at 1 and 2 hours compared to baseline and placebo (p <.01). Thus, AG and AL preparations are safe, well tolerated, and enhance the bioavailability of vitamins C and B(12) and antioxidant potential.

Postprandial metabolic responses to dietary glycemic index in hypercholesterolemic postmenopausal women.

Abstract: Cardiovascular disease (CVD) remains the leading cause of mortality in women in the developed world and is a prime target for prevention.1 Postmenopausal loss of estrogen in women unveils a constellation of closely associated adverse changes in metabolic risk factors.2 The key contributors to this increased risk include a proatherogenic lipid profile, higher prevalence of visceral obesity, insulin resistance, and hypertension.3 Nonesterified (or free) fatty acid (FFA) levels have been implicated as a mechanistic underpinning for the development of the metabolic syndrome and ensuing risk for cardiovascular mortality, and elevated serum triglycerides have been shown to be an independent risk factor for CVD.4 Further, recent studies suggest that nonfasting triglyceride levels, especially those measured 2 to 4 hours postprandially, are strongly associated with cardiovascular events.5 Epidemiologic studies support postprandial lipemia as an independent risk factor for CVD.6,7 Patients with CVD exhibit an increased magnitude and duration of lipemia during the postprandial period,4 with an adverse effect on lipid subfractions associated with oxidative damage and induction of an inflammatory response.8 The close relationship between inflammation and CVD suggests that proinflammatory conditions, as promoted by FFAs, serum triglycerides, and insulin resistance, manifested by a high homeostasis model assessment-insulin resistance (HOMA-IR), may be a possible risk factor for coronary heart disease (CHD) or CHD-related disease, ie, diabetes mellitus (DM), in postmenopausal women.9 Many organizations recommend a diet containing at least 55% total energy from carbohydrates to maintain health and prevent CVD.10,11 However, it is clear that the type of carbohydrate is important. Recommendations emphasize the inclusion of complex carbohydrate and fiber, while reducing intake of simple sugars and carbohydrates associated with high glycemic response.12 In the Nurses Health Study, persons in the highest quintile of glycemic index (GI) (and glycemic load) had nearly double the relative risk of coronary artery disease, compared with those in the lowest quintile after adjustment for known risk factors.13,14 In postmenopausal women, high-GI diets were associated with higher fasting C-reactive protein (CRP) levels, high fasting serum triglycerides, and low serum high-density lipoprotein (HDL) cholesterol;15 yet, their effects on postprandial FFA and lipid levels remain unclear.16 While it is known that menopause represents a cardiovascular risk factor for women,2 it is not known whether the risk might be more pronounced among women with higher levels of postprandial lipemia. Most postprandial studies in women to date have tested plasma glycemic and lipemic response to conditions involving a metabolic stress, such as a very high–fat load or postprandial response to exercise. In contrast, our objective was to study postprandial effects of a high-glycemic vs a low-GI meal, representing a realistic test meal within the recommended food spectrum. We sought to test the hypothesis that a high-compared with a low-GI meal results in an adverse postprandial metabolic response.