Increased fibrosis and angiogenesis in subcutaneous gluteal adipose tissue in nascent metabolic syndrome.

AIMS: Metabolic syndrome (MetS) is globally a common disorder that predisposes to both diabetes and cardiovascular disease (CVD). There is a paucity of data on fibrosis and angiogenesis in adipose tissue (AT) in patients with nascent MetS uncomplicated by diabetes or CVD. Hence, we assayed various indices of fibrosis and angiogenesis in subcutaneous AT (SAT). METHODS: In both patients with MetS and matched controls, we determined fibrosis and the densities of CD31, VEGF and Angiopoietin (Angio) 2 and 1 by immunohistochemistry in gluteal SAT. RESULTS: The fibrosis score was significantly increased in SAT of Met S. Also, both CD31 and VEGF densities were significantly increased. Surprisingly, Angio-2 was not increased and the ratio of Angio2:1 was decreased. Both indices of fibrosis and angiogenesis correlated with biomediators of inflammation. CONCLUSIONS: In conclusion, we report increased fibrosis and paradoxical increased angiogenesis in gluteal SAT and speculate that the increased angiogenesis is a protective mechanism in mitigating further adipose tissue dysregulation in this depot.

The effect of the accessory proteins, soluble CD14 and lipopolysaccharide-binding protein on Toll-like receptor 4 activity in human monocytes and adipocytes.

BACKGROUND: There is a growinge body of evidence pointing towards an important role for Toll-like receptors (TLR) especially TLR4 in obesity and metabolic syndrome. OBJECTIVE: Owing to the paucity of data on the effect of the accessory proteins, lipopolysaccharide (LPS)-binding protein (LBP) and soluble CD14 (sCD14) on TLR4 activation, the present study was undertaken to examine the effect of sCD14 and LBP on TLR4 activation in pivotal cells of meta-inflammation, monocytes and adipocytes. METHODS: The dose-response effects of sCD14 and LBP on TLR4 protein abundance in monocytes obtained from normal human volunteers was determined by flow cytometry and in human-differentiated adipocytes by western blotting. Additionally, the nuclear factor-kappaB (NF-κB) p65 and downstream biomediators interleukin (IL)-1ß, IL-8, IL-6 and tumor necrosis factor (TNF)-α were measured in the cell culture supernatants by ELISA (enzyme-linked immunosorbent assay). RESULTS: In LPS-primed monocytes, sCD14 but not LBP, augments both TLR4 abundance and inflammatory biomediators (IL-1ß, IL-8, IL-6 and TNF-α).sCD14 also showed a similar effect in LPS-primed human adipocytes by augmenting TLR4 protein expression and activity in terms of NF-κB p65 and downstream biomediators (IL-1ß, IL-8, IL-6 and TNF-α). LBP at the highest concentration only promoted secretion of IL-8 and TNF-α. However in both monocytes and adipocytes, the effect of sCD14 was superior to LBP. CONCLUSIONS: In the present report, we make the novel observation that sCD14 compared with LBP, offers a preferred target to ameliorate TLR especially TLR4-induced inflammation and insulin resistance in human obesity and metabolic syndrome.

Anti-inflammatory Strategies to Prevent Diabetic Cardiovascular Disease.

Diabetes is a proinflammatory state and inflammation is crucial in the genesis of vascular complications. While there are many anti-inflammatory strategies, most of which have been shown to reduce inflammation in diabetes, there is sparse data on reduction in cardiovascular events (CVEs). To date, the only anti-inflammatory strategies that have been shown to reduce CVE in diabetes include statins, angiotensin receptor blockers, metformin, and pioglitazone. We also discuss the role of novel emerging therapies.

Circulating pathogen-associated molecular pattern - binding proteins and High Mobility Group Box protein 1 in nascent metabolic syndrome: implications for cellular Toll-like receptor activity.

OBJECTIVE: The Metabolic Syndrome, (MetS) a global epidemic, is a state of low grade chronic inflammation and confers an increased risk for diabetes and CVD. We have previously reported increased activity of the pathogen recognition receptors, Toll-like receptors (TLRs), TLR2 and TLR4 in MetS. We hypothesized that increased TLR activity in MetS is due in part to increased levels of circulating PAMP-binding proteins, soluble CD14 (sCD14), lipopolysaccharide binding protein (LBP) and the damage associated molecular pattern (DAMP), High Mobility Group Box protein 1 (HMGB-1). METHODS: We measured sCD14, LBP and HMGB-1 in fasting plasma from nascent MetS (n = 37) and healthy control subjects (n = 32) by ELISA. We also investigated the effects of sCD14 and LBP on TLR4 activity in human aortic endothelial cells (HAECs). RESULTS: Following adjustment for body mass index and waist circumference, sCD14, LBP and HMGB-1 levels remained significantly increased in MetS. Also their levels increased with increasing numbers of MetS risk factors. Only sCD14 correlated significantly with monocyte TLR4 protein and activity. None of these soluble biomarkers correlated with TLR2 protein. Both sCD14 and HMGB-1 correlated significantly with HOMA-IR. In LPS primed HAECs, sCD14 compared to LBP, resulted in a greater increase in both TLR4 abundance and inflammatory biomediators (NF-κB, IL-1ß, IL-8 and TNF-α). CONCLUSION: Thus, we make the novel observation that sCD14 reflects increased monocyte TLR4 protein and activity in nascent MetS and by contributing to increased cellular inflammation could explain, in part, the increased risk for diabetes and CVD.

Measurement of low-density lipoprotein cholesterol in assessment and management of cardiovascular disease risk.

The deposition of cholesterol in the arterial wall by the infiltration of low-density lipoproteins (LDLs) is a key step in the development of atherosclerosis. In this Commentary, we discuss recent recommendations for clinical laboratory measurement of low-density lipoprotein cholesterol (LDL-C) and its utility both for assessing cardiovascular disease risk and as a tool in the management of patients receiving lipid-lowering therapy.

A novel peptide inhibitor attenuates C-reactive protein's pro-inflammatory effects in-vivo.

BACKGROUND: Higher levels of C-reactive protein (CRP) predict cardiovascular events and also portend a poorer prognosis in patients with acute coronary syndromes. Much in-vitro and in-vivo data support a role for CRP in atherogenesis. METHODS: Using the one-bead-one-compound (OBOC) combinatorial library method we have successfully identified peptides against human CRP that inhibit its biological effects in-vitro. Hence we tested the effect of the best characterized inhibitor (CRP-i2) on the effects of CRP in an appropriate animal model, Wistar rats. RESULTS: Treatment with CRP resulted in significant increase in superoxide anion, nuclear factor kappaB (NFκb) activity and the release of biomarkers of inflammation from macrophages compared to Wistar rats treated with human albumin (HuSA). Pre-treatment with the inhibitor, CRP-i2, resulted in a significant reduction in CRP induced superoxide anion, NFκb activity and biomarkers of inflammation. Also, there were no observed clinical or laboratory related adverse effects. CONCLUSIONS: We demonstrate that our novel peptide inhibitor attenuates the proinflammatory effects of CRP in-vivo. Future studies will examine the long-term effects of this inhibitor on vascular pathobiology.

Small interfering-RNA to protein kinase C-delta reduces the proinflammatory effects of human C-reactive protein in biobreeding diabetic rats.

Type 1 diabetes (T1DM) is a proinflammatory state characterized by increased C-reactive protein (CRP) levels. Previously we reported that human CRP accentuated macrophage activity in spontaneously diabetic biobreeding (BB) rats and also increased protein kinase C (PKC) delta. Hence we tested the effect of molecular inhibition of PKC delta on plasma and macrophage proinflammatory biomarkers using small interfering (si)RNA to PKC delta. Prior to administration of human CRP, daily for 3 days to diabetic rats, scrambled siRNA or siRNA to PKC delta was also delivered for the 3 days, and the animals were sacrificed on day 4. Peritoneal macrophages and plasma were obtained. Compared to scrambled siRNA, siRNA to PKC delta resulted in a significant decrease in biomediators of inflammation in plasma and from macrophages (IL-1, TNF-alpha, IL-6, MCP-1, KC/IL-8, and PAI -1). However, siRNA to PKC delta has no effect on superoxide release from macrophages. In conclusion, our novel data suggests that siRNA to PKC delta attenuates the proinflammatory effect of human CRP in spontaneously diabetic BB rats and could have implications with regard to attenuating inflammation and vascular complications in T1DM.

Low vitamin D levels in Northern American adults with the metabolic syndrome.

Metabolic syndrome (MetS), is a constellation of cardiometabolic disease risk factors, that affects 1 in 3 US adults and predisposes to increased risks for both diabetes and cardiovascular disease. While epidemiological studies show low vitamin D [(25(OH)D] levels in MetS, there is sparse data on vitamin D status in MetS patients in North America. Thus, the aim of our study was to examine plasma vitamin D concentration among adults with MetS in Northern California (sunny climate), but without diabetes or cardiovascular disease. 25(OH)D levels were significantly decreased in MetS compared to controls. 8 % of controls and 30% of MetS North American adult subjects were deficient in 25(OH)D (<20 ng/ml; p=0.0236, Controls vs. MetS). There were no significant differences between the groups with respect to blood sampling in winter and summer months, total calcium and phosphate, and creatinine levels. Vitamin D levels were significantly inversely correlated with fasting glucose (r=-0.29, p=0.04) and HOMA (r=-0.34, p=0.04). Future studies of vitamin D supplementation in these subjects on subsequent risk of diabetes will prove instructive with respect to potential health claims in these high risk patients with MetS.

Bile acid sequestrants and diabetes: introduction and overview to the supplement.

Diabetes is a global epidemic. The recommended goals for glycated hemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-C), and blood pressure are achieved only in a very small minority of patients. In this supplement to Metabolic Syndrome and Related Disorders, we review the data showing that the bile acid sequestrant colesevelam lowers both HbA1c and LDL-C in patients with diabetes. These data make colesevelam an attractive therapy to get more patients to achieve their LDL-C and HbA1c goals.

Decreased number and impaired functionality of endothelial progenitor cells in subjects with metabolic syndrome: implications for increased cardiovascular risk.

OBJECTIVE: Metabolic syndrome (MetS) is characterized by low-grade inflammation and confers an increased risk for cardiovascular disease. Endothelial progenitor cells (EPCs) are a measure of vascular health and are decreased in patients with various risk factors for cardiovascular disease (CVD). There is a paucity of data examining the EPC status especially in terms of their functionality in MetS subjects without diabetes or cardiovascular disease. We aimed to enumerate and functionally characterize EPCs in subjects with MetS in comparison to healthy controls. METHODS: The study was performed at the University of California Davis Medical Center. Healthy controls (n=31) and MetS (n=46) subjects were included in the study. EPCs were enumerated in fasting blood by KDR/CD34 dual positivity. Functionality was assessed by the colony forming units (CFU) assay, migration and tubule formation. RESULTS: Subjects with MetS had significantly decreased number of EPCs compared to control subjects. Furthermore, EPCs from MetS subjects depicted significantly impaired clonogenic capacity, i.e., decreased colony forming units, and impaired capacity to incorporate into tubular structures suggesting functional impairment of EPCs from MetS subjects. CONCLUSIONS: We make the novel observation that MetS subjects without diabetes or CVD have decreased EPC number and impaired functionality as compared to control subjects. These findings could contribute to the increased CV risk in this population.

Increased levels of ligands of Toll-like receptors 2 and 4 in type 1 diabetes.

AIMS/HYPOTHESIS: Type 1 diabetes is a proinflammatory state characterised by increased levels of circulating biomarkers of inflammation and monocyte activity. We have shown increased Toll-like receptor 2 (TLR2) and TLR4 expression and signalling in monocytes from type 1 diabetic patients. Several endogenous ligands of TLR2 and TLR4 have been identified; however, there is a paucity of data on levels of these endogenous ligands in diabetes. Thus, the aim of this study was to examine circulating levels of exogenous/endogenous ligands of TLR2 and TLR4 in type 1 diabetic patients and to compare these with the levels in matched healthy controls. METHODS: Healthy controls (n = 37) and type 1 diabetic patients (n = 34) were recruited, and a fasting blood sample was obtained. Circulating levels of endotoxin, heat-shock protein 60 (Hsp60), high-mobility group box 1 (HMGB1) and growth arrest-specific 6 (GAS6) proteins were assessed by ELISA, and TLR2 and TLR4 expression was determined by flow cytometry. RESULTS: Levels of the classical TLR4 ligand, endotoxin, were significantly elevated in type 1 diabetic patients compared with those in matched controls. Hsp60 and HMGB1 concentrations were also significantly increased in the patients (p < 0.01 and p < 0.001, respectively). No significant differences were observed in GAS6. CONCLUSIONS/INTERPRETATION: We report the novel observation that levels of ligands of TLR2 and TLR4 are significantly elevated in type 1 diabetes, and this, in concert with hyperglycaemia, accounts for the increase in TLR2 and TLR4 activity, underscoring the proinflammatory state of type 1 diabetes.

Human C-reactive protein promotes oxidized low density lipoprotein uptake and matrix metalloproteinase-9 release in Wistar rats.

C-reactive protein (CRP) is present in the atherosclerotic plaques and appears to promote atherogenesis. Intraplaque CRP colocalizes with oxidized low density lipoprotein (OxLDL) and macrophages in human atherosclerotic lesions. Matrix metalloproteinase-9 (MMP-9) has been implicated in plaque rupture. CRP promotes OxLDL uptake and MMP induction in vitro; however, these have not been investigated in vivo. We examined the effect of CRP on OxLDL uptake and MMP-9 production in vivo in Wistar rats. CRP significantly increased OxLDL uptake in the peritoneal and sterile pouch macrophages compared with human serum albumin (huSA). CRP also significantly increased intracellular cholesteryl ester accumulation compared with huSA. The increased uptake of OxLDL by CRP was inhibited by pretreatment with antibodies to CD32, CD64, CD36, and fucoidin, suggesting uptake by both scavenger receptors and Fc-gamma receptors. Furthermore, CRP treatment increased MMP-9 activity in macrophages compared with huSA, which was abrogated by inhibitors to p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), and nuclear factor (NF)-kappaB but not Jun N-terminal kinase (JNK) before human CRP treatment. Because OxLDL uptake by macrophages contributes to foam cell formation and MMP release contributes to plaque instability, this study provides novel in vivo evidence for the role of CRP in atherosclerosis.

Vitamin E, oxidative stress, and inflammation.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the Western world. Its incidence has also been increasing lately in developing countries. Several lines of evidence support a role for oxidative stress and inflammation in atherogenesis. Oxidation of lipoproteins is a hallmark in atherosclerosis. Oxidized low-density lipoprotein induces inflammation as it induces adhesion and influx of monocytes and influences cytokine release by monocytes. A number of proinflammatory cytokines such as interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) modulate monocyte adhesion to endothelium. C-reactive protein (CRP), a prototypic marker of inflammation, is a risk marker for CVD and it could contribute to atherosclerosis. Hence, dietary micronutrients having anti-inflammatory and antioxidant properties may have a potential beneficial effect with regard to cardiovascular disease. Vitamin E is a potent antioxidant with anti-inflammatory properties. Several lines of evidence suggest that among different forms of vitamin E, alpha-tocopherol (AT) has potential beneficial effects with regard to cardiovascular disease. AT supplementation in human subjects and animal models has been shown to decrease lipid peroxidation, superoxide (O2-) production by impairing the assembly of nicotinamide adenine dinucleotide phosphate (reduced form) oxidase as well as by decreasing the expression of scavenger receptors (SR-A and CD36), particularly important in the formation of foam cells. AT therapy, especially at high doses, has been shown to decrease the release of proinflammatory cytokines, the chemokine IL-8 and plasminogen activator inhibitor-1 (PAI-1) levels as well as decrease adhesion of monocytes to endothelium. In addition, AT has been shown to decrease CRP levels, in patients with CVD and in those with risk factors for CVD. The mechanisms that account for nonantioxidant effects of AT include the inhibition of protein kinase C, 5-lipoxygenase, tyrosine-kinase as well as cyclooxygenase-2. Based on its antioxidant and anti-inflammatory activities, AT (at the appropriate dose and form) could have beneficial effects on cardiovascular disease in a high-risk population.

Scientific evidence to support a vitamin E and heart disease health claim: research needs.

In addition to epidemiologic studies suggesting a benefit for high intakes of alpha-tocopherol, studies following supplementation in humans have clearly shown that alpha-tocopherol decreases lipid peroxidation, platelet aggregation, and functions as a potent anti-inflammatory agent. However, prospective human clinical trials with alpha-tocopherol alone and in combination with other antioxidants have been largely negative. In this review, we critically appraise the various clinical trials and provide recommendations for future research.

Nontraditional risk factors for cardiovascular disease in diabetes.

People with type 2 diabetes are disproportionately affected by cardiovascular disease (CVD), compared with those without diabetes. Traditional risk factors do not fully explain this excess risk, and other "nontraditional" risk factors may be important. This review will highlight the importance of nontraditional risk factors for CVD in the setting of type 2 diabetes and discuss their role in the pathogenesis of the excess CVD morbidity and mortality in these patients. We will also discuss the impact of various therapies used in patients with diabetes on nontraditional risk factors.

Oxidative stress, inflammation, and diabetic vasculopathies: the role of alpha tocopherol therapy.

The diabetic state confers an increased propensity to accelerated atherogenesis. In addition to the established risk factors, there is evidence for increased oxidative stress and inflammation in diabetes. Increased oxidative stress is manifested by increased lipid peroxidation (e.g. increased F2-isoprostanes) and increased DNA damage. Evidence for increased inflammation includes increased monocyte superoxide and pro-inflammatory cytokine release (IL-1, IL-6, and TNF-alpha), increased monocyte adhesion to endothelium and increased levels of plasma C-reactive protein, the prototypic marker of inflammation. Most importantly, alpha tocopherol therapy, especially at high doses, clearly shows a benefit with regards to LDL oxidation, isoprostanes and a decrease in inflammatory markers such as C-reactive protein, pro-inflammatory cytokines and PAI-1 levels. Thus, it appears that, in diabetes, alpha tocopherol therapy could emerge as an additional therapeutic modality.