Adiponectin and the metabolic syndrome: mechanisms mediating risk for metabolic and cardiovascular disease

A Mouse Model of Metabolic Syndrome; Increase in Visceral Adipose Tissue Precedes the Development of Fatty Liver and Insulin Resistance in High-Fat Diet-Fed Male KK/Ta Mice

To determine the relative contribution of obesity and visceral white adipose tissue (WAT) to metabolic syndrome, we developed a model that is susceptible to high-fat diet-induced obesity and insulin resistance using male KK/Ta mice. The ratio of WAT weight to body weight was greater in the high-fat diet group compared with the control group in 10-, 14-, and 22-week-old mice. The increase in visceral WAT preceded development of fatty liver and insulin resistance. Adiponectin mRNA expression in WAT was markedly decreased before the decrease in its plasma levels or the development of insulin resistance. Insulin resistance appeared in association with fatty infiltration and TNF-α expression in the liver in 22-week-old mice. These data indicate that our mouse model would be useful for future studies that investigate the role of visceral WAT and its products in the development of metabolic syndrome.

Pentamethylquercetin improves adiponectin expression in differentiated 3T3-L1 cells via a mechanism that implicates PPARγ together with TNF-α and IL-6

Adiponectin is an adipocyte-derived hormone that plays a pivotal role in the regulation of lipid and glucose metabolism. Up-regulation of adiponectin expression and production has been shown to benefit for metabolic disorders, including type 2 diabetes, hyperlipidemia, etc. The present study investigated whether the novel polymethoxylated flavonoid pentamethylquercetin (PMQ), a member of polymethoxylated flavonoids family which is present in seabuckthorn (Hippophae L.) would affect adiponectin production in differentiated 3T3-L1 adipocytes. It was found that PMQ increased the adiponectin mRNA and protein expressions in adipocytes in time- and concentration-dependent manners. The PPARγ pathway plays a important roles in this effect of PMQ because blockade of PPARγ by GW9662 eliminates the PMQ-induced up-regulation of adiponectin expression. Furthermore, significant decreases of mRNA expression and secretion of TNF-α and IL-6 were also observed in PMQ-treated cells. Taken together, our study demonstrated that PMQ up-regulates adiponectin expression via a mechanism that implicates PPARγ together with TNF-α and IL-6, suggesting that PMQ might be a potential candidate for the treatment of metabolic diseases.

Effects of macrophage-specific adiponectin expression on lipid metabolism in vivo

Epidemiological studies have associated low circulating levels of the adipokine adiponectin with multiple metabolic disorders, including metabolic syndrome, obesity, insulin resistance, type II diabetes, and cardiovascular disease. Recently, we reported that adiponectin selectively overexpressed in mouse macrophages can improve insulin sensitivity and protect against inflammation and atherosclerosis. To further investigate the role of adiponectin and macrophages on lipid and lipometabolism in vivo, we engineered the expression of adiponectin in mouse macrophages (Ad-TG mice) and examined effects on plasma lipoproteins and on the expression levels of genes involved in lipoprotein metabolism in tissues. Compared with the wild-type (WT) mice, Ad-TG mice exhibited significantly lower levels of plasma total cholesterol (-21%, P < 0.05) due to significantly decreased LDL (-34%, P < 0.05) and VLDL (-32%, P < 0.05) cholesterol concentrations together with a significant increase in HDL cholesterol (+41%, P < 0.05). Further studies investigating potential mechanisms responsible for the change in lipoprotein cholesterol profile revealed that adiponectin-producing macrophages altered expression of key genes in liver tissue, including apoA1, apoB, apoE, the LDL receptor, (P < 0.05), and ATP-binding cassette G1 (P < 0.01). In addition, Ad-TG mice also exhibited higher total and high-molecular-weight adipnection levels in plasma and increased expression of the anti-inflammatory cytokine IL-10 as well as a decrease in the proinflammatory cytokine IL-6 in adipose tissue. These results indicate that macrophages engineered to produce adiponectin can influence in vivo gene expression in adipose tissue in a manner that reduces inflammation and macrophage infiltration and in liver tissue in a manner that alters the circulating lipoprotein profile, resulting in a decrease in VLDL and LDL and an increase in HDL cholesterol. The data support further study addressing the use of genetically manipulated macrophages as a novel therapeutic approach for treatment of cardiometabolic disease.

Simvastatin suppresses dexamethasone-induced secretion of plasminogen activator inhibitor-1 in human bone marrow adipocytes

Background

Osteonecrosis of the femoral head is a common complication of high-dose glucocorticoid treatment. Intravascular thrombosis is thought to be associated with the ischemic state of the femoral head. Plasminogen activator inhibitor-1 (PAI-1) is an adipokine, which are physiologically active substances secreted from visceral and subcutaneous adipocytes. PAI-1 suppresses fibrinolysis by binding tissue-type plasminogen activator. Several reports have described the relationship between PAI-1 and steroid-induced osteonecrosis of the femoral head, and the preventive effects of lipid-lowering agents (statins) against steroid-induced osteonecrosis of the femoral head. We previously reported that adipokines and dexamethasone induced PAI-1 secretion from bone marrow adipocytes. The purpose of the present study is to examine the effects of simvastatin on PAI-1 secretion from human bone marrow adipocytes in vitro.

Methods

Primary bone marrow adipocytes were extracted from collagenase-treated bone marrow fluid obtained from the femoral necks of 40 patients (6 men, 34 women; age range, 52-81 years) undergoing hip joint replacement surgery. After suspended culture with or without dexamethasone or simvastatin, PAI-1 mRNA expression was assessed by real-time RT-PCR. Total PAI-1 protein secretion in culture medium was assessed by enzyme-linked immunosorbent assay.

Results

PAI-1 mRNA expression was up-regulated by 388% (P = 0.002) with dexamethasone, and down-regulated by 45% (P = 0.002) with simvastatin, as compared to control levels. Dexamethasone increased total PAI-1 secretion by 166% (P = 0.001) and simvastatin decreased total PAI-1 secretion by 64% (P = 0.002). No significant changes were observed in adiponectin mRNA expression and secretion by dexamethasone and simvastatin, while pre-treatment with simvastatin reversed dexamethasone induced PAI-1 secretion by 89%, as compared to control levels.

Conclusion

The present study confirmed the suppressive effects of simvastatin on PAI-1 expression and secretion from bone marrow adipocytes. Furthermore, pre-treatment with simvastatin reversed dexamethasone induced PAI-1 secretion. Simvastatin may thus exhibit preventive effects against steroid-induced osteonecrosis of the femoral head by suppressing PAI-1 secretion.

Relationship between inflammation biomarkers, antioxidant vitamins, and bone mineral density in patients with metabolic syndrome

Few studies have shown the correlation between metabolic syndrome and bone mineral density (BMD). The main pathogenic mechanisms of metabolic syndrome rely on chronic low-level inflammatory status and oxidative stress. There are few studies that examine the gender-specific effects of inflammation and antioxidants on BMD. In this study, we evaluated the relative contribution of these factors in patients with metabolic syndrome. We conducted a cross-sectional study of 67 men and 46 postmenopausal women with metabolic syndrome; metabolic syndrome was defined as having three or more metabolic syndrome risk factors. BMD, body fat mass, and lean body mass were evaluated. We also examined the levels of high sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6), adiponectin, vitamin E, and C in serum. Log-transformed hs-CRP levels were significantly higher in lumbar spine osteoporotic subjects than in normal subjects for women but not for men. There was no significant difference between the normal group and the osteoporotic group in other inflammatory markers. Stepwise regression analyses for BMD of the lumbar spine showed that lean body mass and vitamin E were significant determinants in men. Lean body mass and log-transformed hs-CRP were significant determinants in women Analysis for BMD of the femoral neck showed that lean body mass was a significant determinant for both men and women. There was no significant factor among the inflammatory markers or antioxidant vitamins affecting the femoral neck BMD for either gender. In conclusion, while hs-CRP is an independent predictor of the BMD of the lumbar spine in women, vitamin E showed profound effects on BMD in men but not women with metabolic syndrome.

Disease-modifying antirheumatic drugs increase serum adiponectin levels in patients with rheumatoid arthritis

BACKGROUND

Adiponectin is an adipocyte-derived adipokine with immunosuppressive and anti-inflammatory properties. It also decreases expression of adhesion molecules. In terms of its relationship with acute-phase reactants, there are conflicting results in patients with rheumatoid arthritis (RA).

OBJECTIVES

The objectives of this study were to evaluate the levels of adiponectin in RA patients before and after the treatment with disease-modifying antirheumatic drugs (DMARDs) and to evaluate whether there is a correlation between adiponectin levels and disease activity and acute-phase-response reactants (APRRs).

METHODS

Serum adiponectin levels, APRRs, total and high-density lipoprotein cholesterol (HDL-C), body mass index, and body fat mass were measured in 27 patients with RA before and after the treatment with DMARDs plus prednisolone. An inclusion criterion for RA patients was to be DMARD naive for at least 6 months or to have been newly diagnosed with RA. Twenty patients with osteoarthritis were included in this study as a disease control.

RESULTS

No significant difference was found between RA and osteoarthritis group in terms of baseline adiponectin level. Mean adiponectin level and mean HDL-C level increased significantly compared with mean baseline level after the treatment with DMARDs plus prednisolone (10 [SD, 4.9] vs. 13.9 [SD, 8.7] μg/mL; P < 0.001; 56.8 [SD, 19] vs. 65 [SD, 18] mg/dL, P < 0.004, respectively). APRRs and the 28-joint-count disease activity score decreased significantly at the end of the 3 months of therapy. The adiponectin levels tended to be negatively correlated with acute-phase reactants and disease activity, although no changes were significant. There was a positive correlation between HDL-C and adiponectin levels at 3 month (r = 0.53, P < 0.001). No correlation was found between erythrocyte sedimentation rate and adiponectin levels both at baseline and at 3 months.

CONCLUSION

Adiponectin levels can be modified by effective treatment of rheumatoid arthritis. This suggests that active inflammation may decrease serum adiponectin levels. In consideration of the antiatherogenic and anti-inflammatory features of adiponectin, increased adiponectin levels in patients with RA may result in a more favorable cardiovascular profile.

Metabolic syndrome, adipokines and ghrelin in overweight and obese schoolchildren: results of a 1-year lifestyle intervention programme

The aim of this study was to evaluate the effect of a lifestyle intervention programme (nutrition and exercise counselling) on metabolic syndrome (MS) components, adipokines (leptin, adiponectin) and ghrelin levels in overweight children. A total of 61 overweight children aged 7-9 years (≥ 85th body mass index (BMI) percentile; 27 boys/34 girls) were randomly assigned and completed a 1-year individual (IT) or group-based treatment (GT). Anthropometric and biochemical parameters were assessed at baseline, at 6 months and at 1 year. Twenty-two normal weight children (<85th BMI percentile; 7-9 years old; 13 boys/nine girls) were also evaluated at baseline. Insulin resistance (IR) was determined by the homeostasis model assessment of IR (HOMA-IR). Overweight children presented significantly higher blood pressure, triglycerides, apolipoprotein B, insulin, HOMA-IR, leptin, C-reactive protein and homocysteine levels, while apolipoprotein A-I was significantly lower. At baseline, MS was present in ten overweight children, of which only five maintained it at 1 year. Leptin and ghrelin levels were associated with IR and MS components. MS was predicted by apolipoprotein A-I, insulin and pre-puberty. The lifestyle intervention led to a significant improvement in standard deviation score of BMI, waist circumference/height ratio and lipid profile. Changes in insulin, HOMA-IR, leptin and adiponectin were not significant. Ghrelin behaved differently between IT and GT. The GT intervention seems to be more successful, with a decrease in BMI Z-score and an improvement of metabolic parameters. In conclusion, overweight children have multiple risk factors associated with MS. A lifestyle intervention programme seems to be an effective mean for reducing obesity and MS components and improving adipokines concentrations.

Associations of SNPs in ADIPOQ and subclinical cardiovascular disease in the multi-ethnic study of atherosclerosis (MESA)

Circulating adiponectin is associated with both clinical and subclinical cardiovascular disease (CVD). Variants of the adiponectin gene (ADIPOQ) are associated with clinical CVD, but little is known about associations with subclinical CVD. We studied the association of 11 ADIPOQ single-nucleotide polymorphisms (SNPs) with common and internal carotid intima media thickness (cIMT), presence of coronary artery calcification (CAC), and CAC scores (in those with CAC) in 2,847 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Participants were white (n = 712), African American (n = 712), Chinese (n = 718), and Hispanic (n = 705). All models were adjusted for age, sex, and field site, and stratified by race/ethnic group. African Americans with genotypes AG/GG of rs2241767 had 36% greater (95% confidence interval (CI; 16%, 59%), P = 0.0001) CAC prevalence; they also had a larger common cIMT (P = 0.0043). Also in African Americans, genotypes AG/AA of rs1063537 were associated with a 35% (95% CI (14%, 59%), P = 0.0005) greater CAC prevalence. Hispanics with the AA genotype of rs11711353 had a 37% (95% CI (14%, 66%), P = 0.0011), greater CAC prevalence compared to those with the GG genotype. Additional adjustment for ancestry in African-American and Hispanic participants did not change the results. No single SNP was associated with subclinical CVD phenotypes in Chinese or white participants. There appears to be an association between ADIPOQ SNPs and subclinical CVD in African Americans and Hispanics. Replication as well as assessment of other ADIPOQ SNPs is warranted.

Serum levels of angiopoietin-related growth factor are increased in metabolic syndrome

Angiopoietin-related growth factor (AGF), a novel hepatokine, showed therapeutic implications in diabetic and obese animal models. Although the physiologic functions of human AGF have not yet been identified, serum levels of AGF displayed up-regulation in groups with diseases including preeclampsia and diabetes; and there was little association between genetic variability of AGF and metabolic syndrome-related phenotypes. We analyzed serum levels of AGF and other biochemical and anthropometric markers in 216 Korean persons--the numbers of healthy controls and those with metabolic syndrome were 138 and 78, respectively--to confirm research data from animal models. Women had higher AGF than men (265.01 vs 311.84 ng/mL, P = .003). This study showed that serum AGF levels were significantly higher in subjects with metabolic syndrome (325.89 ng/mL) than those in the healthy group (272.44 ng/mL) (P = .003). Among the components of metabolic syndrome, subjects with high waist circumference or decreased high-density lipoprotein cholesterol had significantly increased serum AGF (271.92 vs 313.68 ng/mL, P = .013; 271.01 vs 310.58 ng/mL, P = .023, respectively). According to multivariate regression analysis, metabolic syndrome itself and waist circumference could be used, in addition to sex and age, as predictors of serum AGF level. In conclusion, serum AGF levels were paradoxically increased in metabolic syndrome, in comparison with data from animal experiments and data on sex, age, and waist circumference. Metabolic syndrome can be a predictor of serum AGF level. Further studies are needed to explore the possibilities of compensatory up-regulation, or AGF resistance, to explain the physiologic roles of AGF in metabolic syndrome.

Altered adipose tissue metabolism in offspring of dietary obese rat dams

To investigate further the mechanisms of developmental programming, we analysed the effects of maternal overnutrition and of postnatal high-fat feeding on adipose tissue metabolism in the offspring. Postnatal changes in serum adiponectin, leptin and TAG [triacylglycerol (triglyceride)] levels, adipose tissue TAGs, fatty acids and enzyme activities were determined in offspring of cafeteria-diet-fed dams during gestation and lactation, weaned on to standard chow or on to cafeteria diet. Obese rats showed higher adiposity (+35% to 85%) as well as a significant increase in serum glucose, insulin, leptin, adiponectin and TAG levels (P<0.01) and adipose tissue LPL (lipoprotein lipase) and GPDH (glycerol-3-phosphate dehydrogenase) activities (P<0.01), compared with control pups at weaning (day 21) and at adulthood (day 90). Adipose HSL (hormone-sensitive lipase) activity was increased only at day 90 (P<0.05), and FAS (fatty acid synthase) activity remained unchanged. The proportions of SFAs (saturated fatty acids) and MUFAs (mono-unsaturated fatty acids) and the Δ9-desaturation index were significantly increased (P<0.05), whereas PUFAs (polyunsaturated fatty acids) were decreased (P<0.01) in serum and adipose TAGs of obese pups compared with controls. The cafeteria diet at weaning induced more severe abnormalities in obese rats. In conclusion, maternal overnutrition induced permanent changes in adipose tissue metabolism of the offspring. These pre-existing alterations in offspring were worsened under a high-fat diet from weaning to adulthood. Consequently, adipose adipokines and enzymes could provide a potential therapeutic target, and new investigations in this field could constitute strategies to improve the impact of early-life overnutrition.

Globular and full-length adiponectin induce NO-dependent vasodilation in resistance arteries of Zucker lean but not Zucker diabetic fatty rats

BACKGROUND

Adiponectin increases nitric oxide (NO) production in endothelial cell cultures and is reduced in the circulation of obese and diabetic patients, but its functional effect on resistance arteries is not yet studied in detail.

METHODS

We assessed the direct vasodilatory response of isolated mesenteric resistance arteries of Zucker diabetic fatty (ZDF) rats and Zucker lean (ZL) rats to globular adiponectin (gAd) and full-length adiponectin (fAd) and tested the effect of additional reactive oxygen species (ROS) inhibitors in vitro. Serum adiponectin and insulin levels were measured by ELISA. The mRNA expressions of the adiponectin receptors and the downstream signaling molecules adaptor protein, phosphotyrosine interaction, PH domain and leucine zipper containing 1 (APPL1), adaptor protein, phosphotyrosine interaction, PH domain and leucine zipper containing 2 (APPL2), and endothelial NO synthase (eNOS) in mesenteric resistance arteries were quantified by real-time reverse transcriptase PCR.

RESULTS

Both gAd and fAd induced a relevant dose-dependent vasodilation in ZL, but not in hypoadiponectinemic ZDF rats. This effect was totally blunted by L-nitroarginine-methyl-ester indicating NO dependency. The addition of ROS inhibitors could not improve the vasodilatory effect of adiponectin. Vasodilatory response to acetylcholine was reduced in ZDF rats, which could not be enhanced by low-dose adiponectin. Adiponectin receptor 1 (AdipoR1) was higher expressed than adiponectin receptor 2 (AdipoR2) with no significant differences between both animal groups, but APPL1 was significantly decreased in ZDF rats. The eNOS expression was not significantly different between ZL and ZDF rats.

CONCLUSIONS

Adiponectin exerts a NO-dependent vasodilation in resistance arteries of normoglycemic ZL rats, but not diabetic ZDF rats. This may contribute to endothelial dysfunction in ZDF rats. Alterations in the expression of APPL1 may be involved in the observed insensitivity to adiponectin in ZDF rats.

Glucose metabolism and body composition in young adults treated with TBI during childhood

After SCT in childhood, survivors may develop disorders of glucose metabolism. The role of obesity is controversial. We measured insulin sensitivity using the homeostasis model assessment (HOMA) and the frequently sampled i.v. glucose tolerance test (FSIVGTT), as well as body composition using dual-energy X-ray absorptiometry in 18 young adults median 18.2 years after SCT and compared them with matched controls. We also measured growth hormone (GH) secretion, and levels of leptin and adiponectin. HOMA showed insulin resistance in eight patients (44%), as opposed to none of the controls (P=0.008) and FSIVGTT showed a decreased sensitivity index in the patients (2.98 vs 4.54 mU/L/min, P=0.042). Dual energy X-ray absorptiometry showed a higher percentage fat mass in the patients (34.9 vs 24.3%, P=0.011), which correlated inversely with the sensitivity index (r=-0.52, P=0.032). The patients had a lower peak value of GH (GH(max) 9 vs 20.7 mU/L, P=0.002). Time post SCT correlated with percentage fat mass and inversely with GH(max). The patients had higher levels of leptin and lower levels of adiponectin, even after adjustment for fat mass. We propose that the decreased insulin sensitivity may primarily be explained by the adverse body composition, which may owe to long-standing GH deficiency.

The role of adipose tissue in mediating the beneficial effects of dietary fish oil

Fish oil improves several features of metabolic syndrome (MetS), such as dyslipidemia, insulin resistance and hepatic steatosis. Fish oil may mediate some of its beneficial effects by modulating the storage and/or secretory functions of adipose tissue (AT). The storage of triglycerides in AT is regulated by the availability of free fatty acids and the degree of lipolysis in AT. Fish oil has been shown to reduce lipolysis in several studies, indicating improved triglyceride storage. Importantly, AT secretes a variety of adipokines and fish oil feeding is associated with remarkable changes in the plasma levels of two key adipokines, adiponectin and leptin. Much attention has been focused on the contribution of adiponectin in fish oil-mediated improvements in MetS. However, emerging evidence also indicates a role of leptin in modulating the components of the MetS upon fish oil feeding. In addition to improving the storage and secretory functions of AT, fish oil, and the n-3 fatty acids found in fish oil, has been shown to reduce inflammation in AT. These effects may be in part a result of activation of peroxisome proliferator-activated receptor γ or inhibition of Toll-like receptor 4. Thus, there is compelling evidence that fish oil mediates its beneficial effects on MetS by improving AT storage and secretory functions and by reducing inflammation.

IL-17 regulates adipogenesis, glucose homeostasis, and obesity

Inflammatory mediators have the potential to impact a surprising range of diseases, including obesity and its associated metabolic syndrome. In this paper, we show that the proinflammatory cytokine IL-17 inhibits adipogenesis, moderates adipose tissue (AT) accumulation, and regulates glucose metabolism in mice. IL-17 deficiency enhances diet-induced obesity in mice and accelerates AT accumulation even in mice fed a low-fat diet. In addition to potential systemic effects, IL-17 is expressed locally in AT by leukocytes, predominantly by γδ T cells. IL-17 suppresses adipocyte differentiation from mouse-derived 3T3-L1 preadipocytes in vitro, and inhibits expression of genes encoding proadipogenic transcription factors, adipokines, and molecules involved in lipid and glucose metabolism. IL-17 also acts on differentiated adipocytes, impairing glucose uptake, and young IL-17-deficient mice show enhanced glucose tolerance and insulin sensitivity. Our findings implicate IL-17 as a negative regulator of adipogenesis and glucose metabolism in mice, and show that it delays the development of obesity.

Imbalance of peroxisome proliferator-activated receptor gamma and adiponectin predisposes Kawasaki disease patients to developing atherosclerosis

BACKGROUND

It remains controversial whether Kawasaki disease (KD) is a risk factor for the onset of atherosclerosis. An imbalance of peroxisome proliferator-activated receptor γ (PPARγ) and adiponectin appears to play a role in the onset of atherosclerosis in adults, and we therefore examined PPARγ mRNA expression and adiponectin profiles in the peripheral white blood cells obtained from KD patients.

METHODS

A total of 50 subjects were studied: nine patients with acute KD, 20 patients with convalescent KD, and 21 age-matched controls. The gene expression of PPARγ, monocyte chemoattractant protein-1, and CC chemokine receptor 2 present in the blood were quantified. The relative gene expression, adiponectin levels, and the three adiponectin isoforms were compared among the subjects.

RESULTS

The abundance of PPARγ and CC chemokine receptor 2 mRNA was significantly increased in convalescent KD patients. The monocyte chemoattractant protein-1 level was also increased in convalescent KD patients. The level of high-molecular-weight adiponectin was significantly lower in convalescent patients compared to controls. The PPARγ transcription levels negatively correlated with apolipoprotein A-I levels in acute KD patients.

CONCLUSIONS

The transcript abundance of PPARγ and low levels of high-molecular-weight adiponectin in KD patients may have important clinical implications on the development of premature atherosclerosis. Because the potential risk for developing atherosclerosis has not yet been verified, long-term observation is important, even in convalescent KD patients without coronary artery lesions.

Insulin resistance is the best predictor of the metabolic syndrome in subjects with a first-degree relative with type 2 diabetes

Although obesity is associated with insulin resistance and the metabolic syndrome (MetS), some obese individuals are metabolically healthy. Conversely, some lean individuals are insulin resistant (IR) and at increased cardiometabolic risk. To determine the relative importance of insulin sensitivity, BMI and waist circumference (WC) in predicting MetS, we studied these two extreme groups in a high-risk population. One thousand seven hundred and sixty six subjects with a first-degree relative with type 2 diabetes were stratified by BMI and homeostasis model assessment of insulin resistance (HOMA(IR)) into groups. IR groups had higher triglycerides, fasting glucose, and more diabetes than their BMI-group insulin sensitive (IS) counterparts. Within both IS and IR groups, obesity was associated with higher HOMA(IR) and diastolic blood pressure (BP), but no difference in other metabolic variables. MetS (Adult Treatment Panel III (ATPIII)) prevalence was higher in IR groups (P < 0.001) and more subjects met each MetS criterion (P < 0.001). Within each BMI category, HOMA(IR) independently predicted MetS (P < 0.001) whereas WC did not. Within IS and IR groups, age and WC, but not BMI, were independent determinants of MetS (P < 0.001). WC was a less meaningful predictor of MetS at higher values of HOMA(IR). HOMA(IR) was a better predictor of MetS than WC or BMI (receiver operating characteristic (ROC) area under the curve 0.76 vs. 0.65 vs. 0.59, P < 0.001). In conclusion, insulin sensitivity rather than obesity is the major predictor of MetS and is better than WC at identifying obese individuals with a healthier metabolic profile. Further, as many lean individuals with a first-degree relative with type 2 diabetes are IR and metabolically unhealthy, they may all benefit from metabolic testing.

Association of serum adiponectin levels with artherosclerosis and the metabolic syndrome in obese children

BACKGROUND

The atherosclerotic process starts at an early age and is linked to obesity. However, the exact pathophysiological mechanism is poorly understood.

OBJECTIVE

To investigate the relationship between serum adiponectin and metabolic syndrome and early arteriosclerosis.

SUBJECTS

176 obese and 88 normal children.

METHODS

Ultrasound measurement was performed to investigate IMT, FMD, carotid artery compliance (CAC). Adiponectin was measured by enzyme-linked immunosorbent assay.

RESULTS

Adiponectin levels correlated negatively with obese markers, blood pressure, fasting insulin, high sensitive CRP, HOMA-IR and IMT; marginally positively associated with CAC and HDL-c. The risk of metabolic syndrome increased 3.43 times when adiponectin levels were less than 7060 ng/ml. Heavy obesity, hypertension, low HDL-c, fasting hyperinsulin, High LDL-c and metabolic syndrome percentage were different in three groups according to the cut-off value of adiponectin.

CONCLUSIONS

Low adiponectin levels are associated with a high incidence of metabolic syndrome.

Eating ourselves to death (and despair): the contribution of adiposity and inflammation to depression

Obesity and related metabolic conditions are of epidemic proportions in most of the world, affecting both adults and children. The accumulation of lipids in the body in the form of white adipose tissue in the abdomen is now known to activate innate immune mechanisms. Lipid accumulation causes adipocytes to directly secrete the cytokines interleukin (IL) 6 and tumor necrosis factor alpha (TNFalpha), but also monocyte chemoattractant protein 1 (MCP-1), which results in the accumulation of leukocytes in fat tissue. This sets up a chronic inflammatory state which is known to mediate the association between obesity and conditions such as cardiovascular disease, type 2 diabetes, and cancer. There is also a substantial literature linking inflammation with risk for depression. This includes the observations that: (1) people with inflammatory diseases such as multiple sclerosis, cardiovascular disease, and psoriasis have elevated rates of depression; (2) many people administered inflammatory cytokines such as interferon alpha develop depression that is indistinguishable from depression in non-medically ill populations; (3) a significant proportion of depressed persons show upregulation of inflammatory factors such as IL-6, C-reactive protein, and TNFalpha; (4) inflammatory cytokines can interact with virtually every pathophysiologic domain relevant to depression, including neurotransmitter metabolism, neuroendocrine function, and synaptic plasticity. While many factors may contribute to the association between inflammatory mediators and depression, we hypothesize that increased adiposity may be one causal pathway. Mediational analysis suggests a bi-directional association between adiposity and depression, with inflammation possibly playing an intermediary role.

Adiponectin is produced by lymphocytes and is a negative regulator of granulopoiesis

Lymphocytes have long been established to play an important role in the regulation of hematopoiesis and produce many cytokines that act on hematopoietic progenitor cells. Previous studies by our group have shown that normal, unstimulated lymphocytes produce a protein that inhibits normal bone marrow GM colony formation. Adiponectin is an adipokine that has been demonstrated to act as a negative regulator of hematopoiesis and immune function. This study aimed to determine if the inhibitory molecule that we described previously was adiponectin. Here, we show transcription, translation, and secretion of adiponectin from lymphocytes and demonstrate that its receptors, AdipoR1 and AdipoR2, are expressed by bone marrow MNCs. We show that although the adiponectin expression is low in lymphocytes, it is sufficient to induce a significant inhibitory effect on GM precursors (CFU-GM) and activate the AMPK pathway in these cells. The regulation of adiponectin production by lymphocytes and its detailed function in suppressing GM colony formation need to be elucidated now. Our findings suggest a functional role for adiponectin as a negative regulator of granulopoiesis.

Insulin-resistance and metabolic syndrome are related to executive function in women in a large family-based study

While type 2 diabetes is well-known to be associated with poorer cognitive performance, few studies have reported on the association of metabolic syndrome (MetS) and contributing factors, such as insulin-resistance (HOMA-IR), low adiponectin-, and high C-reactive protein (CRP)- levels. We studied whether these factors are related to cognitive function and which of the MetS components are independently associated. The study was embedded in an ongoing family-based cohort study in a Dutch population. All participants underwent physical examinations, biomedical measurements, and neuropsychological testing. Linear regression models were used to determine the association between MetS, HOMA-IR, adiponectin levels, CRP, and cognitive test scores. Cross-sectional analyses were performed in 1,898 subjects (mean age 48 years, 43% men). People with MetS had significantly higher HOMA-IR scores, lower adiponectin levels, and higher CRP levels. MetS and high HOMA-IR were associated with poorer executive function in women (P = 0.03 and P = 0.009). MetS and HOMA-IR are associated with poorer executive function in women.

Association between plasma adiponectin and high-density lipoprotein cholesterol in postmenopausal women

OBJECTIVES

We investigated the association of plasma adiponectin and high-density lipoprotein cholesterol (HDL-C) in postmenopausal women.

DESIGN AND METHODS

This was a cross-sectional study of 563 postmenopausal women with and 1029 without low HDL-C. Lipid profile, glucose, adiponectin, IL-1beta, IL-6, and TNF-alpha concentrations were measured.

RESULTS

Plasma adiponectin levels increased with age in elderly women. Plasma adiponectin levels were lower in subjects with low HDL-C (<50mg/dl), when compared with normal HDL-C subjects. In multiple stepwise linear regression analysis, adiponectin was a significant independent predictor of HDL-C concentration with body mass index, total cholesterol, and triglycerides. Values in the third and fourth quartile of adiponectin were associated with decreased odds ratio for low HDL-C (0.62; 95% CI, 0.44-0.87, 0.40; 95% CI, 0.27-0.58, respectively) when compared with values in the lowest quartile after multivariable adjustment.

CONCLUSIONS

Adiponectin was significantly associated with HDL-C concentration in postmenopausal women. These findings suggest that high adiponectin levels may have a protective effect on atherosclerosis with increasing HDL-C in postmenopausal women.

Hyperuricaemia and the metabolic syndrome in type 2 DM

BACKGROUND

Elevated serum uric acid levels (SUA) have been associated with an increased risk of cardiovascular diseases and the metabolic syndrome (MetS) and are often reported to be higher in females than in males. The aim of this report is to determine the prevalence and clinical correlates of hyperuricaemia and also to evaluate associations with the MetS in people with type 2 diabetes mellitus (DM).

METHODS

This was a cross-sectional study conducted in people with type 2 DM in Lagos, Nigeria. Hyperuricaemia was defined by cut-off values of > 7 mg/dl for men and > 6 mg/dl for women. The diagnosis of MetS was made using the new definition by the American Heart Association and other related bodies. Clinical and biochemical parameters were compared between subjects with hyperuricaemia and normouricaemia. Statistical analysis included usage of Student's t test, Pearson correlation coefficients, multivariate regression analysis and chi square.

RESULTS

601 patients with type 2 DM aged between 34-91 years were recruited for the study. The prevalence rates of hyperuricaemia and the MetS were 25% and 60% respectively. The frequency of occurrence of hyperuricaemia was comparable in both genders (59% vs 41%, p = 0.3). Although, the prevalence of the MetS in subjects with hyperuricaemia and normouricaemia was comparable (61 vs 56%, p = 0.1), a higher proportion of hyperuricaemic subjects had 3 or more components of the Mets compared with normouricaemic subjects. Possible predictors of hyperuricaemia include central obesity, smoking and elevated serum triglycerides (TG). SUA levels were found to be positively and significantly associated with serum TG (r = 0.2, p = 0.0001) and total cholesterol (r = 13, p = 0.001).

CONCLUSION

The prevalence of hyperuricaemia in subjects with type 2 DM is comparable in both genders and possible predictors of hyperuricaemia are potentially modifiable. SUA is positively and significantly associated with serum TG and total cholesterol.

Overproduced interleukin 6 decreases blood lipid levels via upregulation of very-low-density lipoprotein receptor

BACKGROUND

Interleukin 6 (IL6) blockade raises blood lipid levels in patients with rheumatoid arthritis.

OBJECTIVE

To examine the influence of IL6 on lipid metabolism.

METHODS

Vascular smooth muscle cells (VSMC) were cultured in the presence of IL6, soluble IL6 receptor (sIL6R), IL6+sIL6R or tumour necrosis factor alpha (TNFalpha) for 24 h. After culture, the expression of very-low-density lipoprotein receptor (VLDLR), low-density lipoprotein receptor (LDLR) and low-density lipoprotein-related protein-1 (LRP-1) were measured by real-time PCR. Human IL6 was injected into mice twice a day for 2 weeks and then VLDLR expression in several tissues and the change of total cholesterol (TC) and triglyceride (TG) levels were investigated. Finally, the effect of anti-IL6 receptor (IL6R) antibody injection on blood lipid levels was examined.

RESULTS

IL6+sIL6R significantly induced expression of VLDLR mRNA in VSMC (8.6-fold, p<0.05), but IL6 or sIL6R alone and TNFalpha did not do so. None of these cytokines induced LDLR and LRP-1 mRNA expression. IL6 injection into mice increased the expression of VLDLR in heart, adipose tissue and liver and decreased TC and TG levels. The injection of anti-IL6R antibody normalised the reduced levels of TC and TG caused by IL6 injection, whereas it had no influence on the levels of TC and TG in normal mice.

CONCLUSIONS

Overproduced IL6 decreased blood lipid levels by increasing VLDLR expression in several tissues. It is concluded that IL6 blockade normalises reduced lipid levels caused by IL6, but does not affect normal lipid metabolism.

eNOS plays a major role in adiponectin synthesis in adipocytes

Nitric oxide (NO) stimulates mitochondrial biogenesis. We recently reported that adiponectin synthesis is regulated by mitochondrial function in adipocytes. This study was undertaken to test the hypothesis that endothelial NO synthase (eNOS) plays an important role in adiponectin synthesis by producing NO and enhancing mitochondrial function in adipocytes. We examined the effects of eNOS knockdown on adiponectin synthesis in 3T3-L1 adipocytes and also examined plasma adiponectin levels and the mitochondria in adipose tissue of eNOS knockout (eNOS(-/-)) mice with and without chronic administration of a NO donor. In cultured 3T3-L1 adipocytes, eNOS siRNA decreased rosiglitazone-induced adiponectin secretion, which was associated with decreases in mitochondrial proteins and biogenesis factors. Plasma adiponectin concentrations were reduced in adult eNOS(-/-) mice compared with age-matched wild-type mice. Mitochondrial contents in adipose tissue were reduced in eNOS(-/-) mice, and this was associated with decreased expression of mitochondrial biogenesis factors, increased levels of 8-hydroxyguanosine, a biomarker of oxidative stress, and morphological abnormalities in mitochondria. Rosiglitazone-induced increases in adiponectin expression and mitochondrial content were also reduced significantly in eNOS(-/-) mice. Chronic administration of a NO donor reversed mitochondrial abnormalities and increased adiponectin expression in adipose tissue of eNOS(-/-) mice. eNOS plays an important role in adiponectin synthesis in adipocytes by increasing mitochondrial biogenesis and enhancing mitochondrial function.

Overcoming metabolic syndrome in severe obesity: adiponectin as a marker of insulin sensitivity and HDL-cholesterol improvements after gastric bypass

OBJECTIVE

To assess the relationship between adiponectin and metabolic parameters in severely obese women during surgical-induced weight loss.

METHODS

Nineteen lean (CT - BMI:21.2 +/- 0.3 kg.m(2)), 14 overweight/class II obese (OB/OW - BMI: 29.7 +/- 0.7 kg/m(2)) and 8 morbidly obese (OBIII - BMI: 56.4 +/- 3.6 kg/m(2)) were evaluated by hyperinsulinemic-euglycemic clamp, adiponectin, and lipids. OBIII were evaluated at 5th and 16th month post-operatively.

RESULTS

Compared to lean, obese groups had lower adiponectin (OB/OW: 9.4 +/- 0.9, OBIII: 7.1 +/- 1.3 versus 12.2 +/- 0.9 ng/dL; p < 0.01), lower HDL-cholesterol (OB/OW:1.05 +/- 0.05, OBIII: 0.88 +/- 0.04 versus 1.22 +/- 0.07 mmol/L; p < 0.01) and insulin resistance-IR (glucose uptake, M-value - OB/OW: 43.6 +/- 2.7, OBIII: 32.4 +/- 3.2 versus 20.0 +/- 1.8 umol/kgFFM.min; p < 0.001). Considering all subjects, adiponectin levels were inversely correlated to BMI and waist circumference, and directly to M-value and HDL-cholesterol (p < 0.01). During weight loss, improvements in IR (Study III: 36.1 +/- 3.9 umol/kg/FFM.min, p < 0.0001), adiponectin (11.8 +/- 1.4 ng/dL, p = 0.006) and HDL-cholesterol were observed (1.10 +/- 0.04 mmol/L, p = 0.007). Moreover, HDL-cholesterol improvement was significantly and independently related to variations of adiponectin and BMI (r(2) = 0.86; p < 0.0002).

CONCLUSIONS

The improvements of IR and adiponectin were related to surgical-induced weight loss, suggesting an important role of adiponectin in HDL-cholesterol regulation.

The aporphine alkaloid boldine induces adiponectin expression and regulation in 3T3-L1 cells

Adiponectin is an adipokine secreted by differentiated adipocytes. Clinical studies suggest a negative correlation between oxidative stress and adiponectin levels in patients with metabolic syndrome or cardiovascular disease. Natural compounds that can prevent oxidative stress mediated inhibition of adiponectin may be potentially therapeutic. Boldine, an aporphine alkaloid abundant in the medicinal plant Peumus boldus, is a powerful antioxidant. The current study demonstrates the effects of boldine on the expression of adiponectin and its regulators, CCAAT/enhancer binding protein-alpha (C/EBPalpha) and peroxisome proliferator-activated receptor (PPAR)-gamma, in 3T3-L1 cells. Differentiated 3T3-L1 adipocytes were exposed to either hydrogen peroxide (H(2)O(2)) (100 microM) or tumor necrosis factor-alpha (TNFalpha) (1 ng/mL) for 24 hours in the presence or absence of increasing concentrations of boldine (5-100 microM). Quantitative polymerase chain reaction showed that both the oxidants decreased the mRNA levels of adiponectin, PPARgamma, and C/EBPalpha to half of the control levels. Boldine, at all concentrations, counteracted the inhibitory effect of H(2)O(2) or TNFalpha and increased the expression of adiponectin and its regulators. The effect of boldine on adiponectin expression was biphasic, with the lower concentrations (5-25 microM) having a larger inductive effect compared to higher concentrations (50-100 microM). Boldine treatment alone in the absence of H(2)O(2) or TNFalpha was also able to induce adiponectin at the inductive phase of adipogenesis. Peroxisome proliferator response element-luciferase promoter transactivity analysis showed that boldine interacts with the PPAR response element and could potentially modulate PPAR responsive genes. Our results indicate that boldine is able to modulate the expression of adiponectin and its regulators in 3T3-L1 cells and has the potential to be beneficial in obesity-related cardiovascular disease.

Association between adiponectin and metabolic syndrome in older adults from major cities of China

OBJECTIVE

To investigate the association between adiponectin and metabolic syndrome (MetS) and related diseases in older adults from major cities of China.

METHODS

A total of 2 049 adults at the age of 60-96 years from 18 major cities of China were enrolled in the study. Plasma adiponectin and insulin concentrations were measured. Insulin resistance was assessed by homeostasis model assessment of insulin resistance (HOMA-IR). The definitions proposed by International Diabetes Federation (IDF) and American Heart Association/National Heart, Lung, and Blood Institute (AHA/NLHBI) were used to identify MetS.

RESULTS

The adiponectin concentration increased with the advance of age and was higher in women than in men. The sex specific adiponectin concentration was inversely correlated with body mass index (BMI), waist circumference, diastolic blood pressure, triglycerides, glucose and fasting blood insulin, and positively correlated with HDL-C (P < 0.001). The adiponectin concentration decreased with increasing MetS components. Compared with the 4th sex-specific adiponectin quartile, the odds ratio (OR) for prevalent MetS-IDF and MetS-AHA/NLHBI in subjects of the 1st quartile group was 3.25 (95% CI: 2.24, 4.71) and 3.21 (95% CI: 2.26, 4.55), respectively. The association was independent of age, sex, life-style factors, medication, family history of chronic diseases, BMI, and HOMA-IR. The OR for MetS was much higher than those of MetS components and its related diseases.

CONCLUSION

Adiponectin is strongly associated with MetS independent of insulin resistance and obesity in older adults from major cities in China. The adiponectin concentration is a useful predictor for the risk of MetS.

Diet-induced weight loss and exercise alone and in combination enhance the expression of adiponectin receptors in adipose tissue and skeletal muscle, but only diet-induced weight loss enhanced circulating adiponectin

OBJECTIVE

The aim of the study was to investigate the effect of weight loss and exercise independently and in combination on circulating levels of adiponectin including low molecular weight, medium molecular weight, and high molecular weight adiponectin and expression of adiponectin and adiponectin receptors (AdipoR) in adipose tissue (AT) and skeletal muscle (SM).

DESIGN AND METHODS

Seventy-nine obese males and females were randomized into the following: 1) exercise only (12 wk of exercise without diet restriction); 2) hypocaloric diet [8 wk of very low energy diet (600 kcal/d) followed by 4 wk with a weight maintenance diet]; and 3) hypocaloric diet and exercise (DEX; 8 wk very low energy diet 800 kcal/d followed by 4 wk weight maintenance diet combined with exercise throughout the 12 wk). Blood samples and biopsies from sc abdominal AT and SM were collected at baseline and after 12 wk. The molecular subforms of adiponectin in serum were determined by Western blot.

RESULTS

The mRNA expression of AdipoR1 and -2 in SM was increased significantly in the exercise-only and DEX groups (both P < 0.05). The mRNA expression of adiponectin and AdipoRs in AT was increased significantly in all three groups (all P < 0.01), whereas serum total circulating adiponectin was significantly increased only in the DEX and hypocaloric diet groups (both P < 0.01). All the adiponectin subforms changed in a similar manner as total adiponectin, indicating no specific regulation of any of the subforms by the intervention.

CONCLUSION

Exercise alone and in combination with a diet-induced weight loss enhance the mRNA expression of adiponectin receptors in AT and in SM but only a pronounced hypocaloric-induced weight-loss increases circulating adiponectin in obese subjects.

Disulfide-dependent self-assembly of adiponectin octadecamers from trimers and presence of stable octadecameric adiponectin lacking disulfide bonds in vitro

Adiponectin is a circulating insulin-sensitizing hormone that homooligomerizes into trimers, hexamers, and higher molecular weight (HMW) species. Low levels of circulating HMW adiponectin appear to increase the risk for insulin resistance. Currently, assembly of adiponectin oligomers and, consequently, mechanisms responsible for decreased HMW adiponectin in insulin resistance are not well understood. In the work reported here, we analyzed the reassembly of the most abundant HMW adiponectin species, the octadecamer, following its collapse to smaller oligomers in vitro. Purified bovine serum adiponectin octadecamer was treated with reducing agents at pH 5 to obtain trimers. These reduced trimers partially and spontaneously reassembled into octadecamers upon oxidative formation of disulfide bonds. Disulfide bonds appear to occupy a greater role in the process of oligomerization than in the structural stabilization of mature octadecamer. Stable octadecamers lacking virtually all disulfide bonds could be observed in abundance using native gel electrophoresis, dynamic light scattering, and collision-induced dissociation nanoelectrospray ionization mass spectrometry. These findings indicate that while disulfide bonds help to maintain the mature octadecameric adiponectin structure, their more important function is to stabilize intermediates during the assembly of octadecamer. Adiponectin oligomerization must proceed through intermediates that are at least partially reduced. Accordingly, fully oxidized adiponectin hexamers failed to reassemble into octadecamers at a rate comparable to that of reduced trimers. As the findings from the present study are based on in vitro experiments, their in vivo relevance remains unclear. Nevertheless, they describe a redox environment-dependent model of adiponectin oligomerization that can be tested using cell-based approaches.

Gluteofemoral body fat as a determinant of metabolic health

Body fat distribution is an important metabolic and cardiovascular risk factor, because the proportion of abdominal to gluteofemoral body fat correlates with obesity-associated diseases and mortality. Here, we review the evidence and possible mechanisms that support a specific protective role of gluteofemoral body fat. Population studies show that an increased gluteofemoral fat mass is independently associated with a protective lipid and glucose profile, as well as a decrease in cardiovascular and metabolic risk. Studies of adipose tissue physiology in vitro and in vivo confirm distinct properties of the gluteofemoral fat depot with regards to lipolysis and fatty acid uptake: in day-to-day metabolism it appears to be more passive than the abdominal depot and it exerts its protective properties by long-term fatty acid storage. Further, a beneficial adipokine profile is associated with gluteofemoral fat. Leptin and adiponectin levels are positively associated with gluteofemoral fat while the level of inflammatory cytokines is negatively associated. Finally, loss of gluteofemoral fat, as observed in Cushing's syndrome and lipodystrophy is associated with an increased metabolic and cardiovascular risk. This underlines gluteofemoral fat's role as a determinant of health by the long-term entrapment of excess fatty acids, thus protecting from the adverse effects associated with ectopic fat deposition.

Prevalence and gender distribution of the metabolic syndrome

BACKGROUND

The Metabolic syndrome (MetS) is a cardiovascular risk factor of public health significance and of recent has become a topical issue. The prevalence of diabetes mellitus (DM) is on the increase and with this scenario, a possible increase in burden of DM which may be largely attributed to cardiovascular complications is expected. The objective of this report is to determine the prevalence of the MetS and compare gender characteristics in subjects with type 2 DM.

METHODS

Subjects with type 2 DM were recruited from an urban hospital for the study. Clinical data was obtained by interviewing the patients and referring to their case folders. The anthropometric indices and blood pressure measurements were documented. Laboratory parameters analysed for included total cholesterol, high density and low density cholesterol, triglyceride and glycosylated haemoglobin. Statistical analysis included usage of Student's t test and chi square.

RESULTS

963 patients with type 2 DM aged between 35-85 years were recruited for the study. The main outcome measures included the prevalence of the metabolic syndrome and the gender differences of its components. The prevalence of the metabolic syndrome was 86%. The frequency of occurrence of the MetS was similar for men (83%) and women (86%) and increased with age in both sexes. The prevalence of MetS increased from 11% among participants aged 20 through 29 years to 89% in participants aged 70 through 79. In our patients with DM, the commonest occurring and least detected MetS defining parameters are central obesity and elevated triglyceride levels respectively. The components of the MetS that differed significantly in both sexes was HDL-C. The combination of the components of the MetS were comparable in both genders and 5.8% of the subjects with the MetS had all components of the MetS.

CONCLUSION

The prevalence of the MetS in type 2DM is high in both genders and increases with age thus posing a potential high cardiovascular risk in this group of patients. The modifiable risk factors for the MetS should be a focus point in the management of subjects with type 2 DM.

Fasting adiponectin is inversely correlated with metabolic syndrome in patients with coronary artery disease

OBJECTIVE

Hypoadiponectemia was observed to correlate with the prevalence or extent of coronary artery disease (CAD), the relationship between metabolic syndrome and fasting serum adiponectin concentration in CAD patients are not well elucidated.

PATIENTS AND METHODS

Fasting blood samples were obtained from 98 CAD patients. Metabolic syndrome and its components were defined using the diagnostic criteria of the International Diabetes Federation. Adiponectin concentrations were measured using a commercial enzyme immunoassay kit.

RESULTS

Fifty patients with CAD (51.0%) had metabolic syndrome. For this group of patients, fasting adiponectin concentrations were found to correlate inversely with metabolic syndrome (p=0.009). Fasting adiponectin values for these subjects also tended to decrease as the number of diagnostic criteria for metabolic syndrome increased (p=0.024). CAD patients with hyperlipidemia (p=0.002), obesity (p=0.030) or receiving statin therapy (p=0.005) had lower serum adiponectin values. By univariate linear regression analysis, fasting serum adiponectin values were positively correlated with age (r=0.242; p=0.017) and high density lipoprotein-cholesterol concentration (HDL-cholesterol; r=0.267; p=0.008) but were negatively correlated with triglyceride concentration (TG; r=-0.251; p=0.013). Multivariate forward stepwise linear regression analysis of the significant variables revealed that HDL-cholesterol concentration (R square=0.071, p=0.008) and age (R square=0.039, p=0.044) are the independent predictors of fasting serum adiponectin concentration for patients with CAD.

CONCLUSION

Serum adiponectin concentration is inversely correlated with metabolic syndrome and the number of metabolic syndrome criteria in patients with CAD. For these patients HDL-cholesterol concentration and age are independent predictors of the serum adiponectin value.

Adiponectin expression is induced by vitamin E via a peroxisome proliferator-activated receptor gamma-dependent mechanism

Adiponectin is a well-known adipokine secreted by adipocytes that presents insulin-sensitizing properties. The regulation of expression of this adipokine by micronutrients is largely unknown. We demonstrate here that adiponectin expression is induced in adipocytes after exposure to tocopherols via the peroxisome proliferator-activated receptor gamma (PPARgamma) pathway. Vitamin E force feeding resulted in an induction of adiponectin in mice at both mRNA and protein levels. Adiponectin mRNA and protein secretion were also increased by vitamin E (alpha- and gamma-tocopherol) in 3T3-L1 cells, together with PPARgamma mRNA, independent of an antioxidant effect. In transient transfections, both alpha- and gamma-vitamers induced the luciferase gene reporter under the control of a human adiponectin promoter via a PPAR-responsive element. The induction of adiponectin by tocopherols seems to be PPARgamma dependent, because it was blocked by the specific antagonist GW9662. Finally, we showed that intracellular concentrations of a PPARgamma endogenous ligand, 15-deoxy-Delta12,14-prostaglandin J2, increased after treatment with tocopherols in 3T3-L1 cells. In summary, vitamin E up-regulates adiponectin expression via a mechanism that implicates PPARgamma together with its endogenous ligand 15-deoxy-Delta12,14-prostaglandin J2. The induction of adiponectin via an original molecular mechanism could be considered as the basis for the beneficial effect of vitamin E on insulin sensitivity.

Low plasma adiponectin level, white blood cell count and Helicobacter pylori titre independently predict abnormal pancreatic beta-cell function

Adiponectin is an adipocytokine with insulin sensitizing effect while chronic inflammation damages pancreatic beta-cells leading to reduced insulin response. We aimed to prove the hypothesis that adiponectin levels and inflammatory markers (white blood cell counts [WCC], Helicobacter pylori [HP] titers, high sensitivity C-reactive protein [hs-CRP]) may interact to affect risk of diabetes. We studied 288 Chinese men (age-median: 41.0 years, IQR: 35.3-46.0 years) being recruited from the community in Hong Kong. The mean adiponectin level was 5.39+/-2.81 microg/ml and 40.9% (n=107) had low adiponectin level (<4 microg/ml). On multiple regression analysis, adiponectin was negatively associated with diabetes, HOMA insulin resistance top quartile, plasma glucose (PG) and 2h insulin; and positively associated with HOMA insulin sensitivity index. WCC was independently associated with PG and 15' insulin, and negatively associated with HOMA insulin sensitivity top quartile. HP titre was associated with 30' PG level and diabetes. hs-CRP did not enter the multivariable model. In conclusion, adiponectin, WCC and HP titer are independent predictors for hyperglycemia and reduced insulin sensitivity in Chinese men. These findings may explain the high risk for diabetes in Chinese population despite their relatively low adiposity.

Diabetes mellitus in long-term survivors of childhood cancer. Increased risk associated with radiation therapy: a report for the childhood cancer survivor study

BACKGROUND

Childhood cancer survivors are at increased risk of morbidity and mortality. To further characterize this risk, this study aimed to compare the prevalence of diabetes mellitus (DM) in childhood cancer survivors and their siblings.

METHODS

Participants included 8599 survivors in the Childhood Cancer Survivor Study (CCSS), a retrospectively ascertained North American cohort of long-term survivors who were diagnosed between 1970 and 1986 as well as 2936 randomly selected siblings of the survivors. The main outcome was self-reported DM.

RESULTS

The mean ages of the survivors and the siblings were 31.5 years (age range, 17.0-54.1 years) and 33.4 years (age range, 9.6-58.4 years), respectively. Diabetes mellitus was reported in 2.5% of the survivors and 1.7% of the siblings. After adjustment for body mass index, age, sex, race/ethnicity, household income, and insurance, the survivors were 1.8 times more likely than the siblings to report DM (95% confidence interval [CI], 1.3-2.5; P < .001), with survivors who received total body irradiation (odds ratio [OR], 12.6; 95% CI, 6.2-25.3; P < .001), abdominal irradiation (OR, 3.4; 95% CI, 2.3-5.0; P < .001), and cranial irradiation (OR, 1.6; 95% CI 1.0-2.3; P = .03) at increased risk. In adjusted models, an increased risk of DM was associated with total body irradiation (OR, 7.2; 95% CI, 3.4-15.0; P < .001), abdominal irradiation (OR, 2.7; 95% CI, 1.9-3.8; P < .001), use of alkylating agents (OR, 1.7; 95% CI, 1.2-2.3; P < .01), and younger age at diagnosis (0-4 years; OR, 2.4; 95% CI, 1.3-4.6; P < .01).

CONCLUSION

Childhood cancer survivors treated with total body or abdominal irradiation have an increased risk of diabetes that appears unrelated to body mass index or physical inactivity.

Comparison of adiponectin, leptin and leptin to adiponectin ratio as diagnostic marker for metabolic syndrome in older adults of Chinese major cities

The aim of this study was to compare the strength of association between metabolic syndrome (MetS) and adiponectin, leptin and leptin to adiponectin ratio (L/A) in older Chinese. This study included 950 males (220 with MetS) and 1096 females (452 with MetS), aged 60-96 years from 18 major cities of the 2002 China National Nutrition and Health Survey. The associations of adiponectin, leptin and L/A with components of MetS and MetS were examined using logistic regression and the receiver operating characteristic (ROC) curves. The correlation coefficients of MetS components except fasting glucose with leptin were similar to those with L/A and higher than those with adiponectin. After adjusting for age and BMI, the odds ratio for MetS corresponding to 1 SD change in L/A was higher than those for leptin and adiponectin. L/A had highest area under the curve (AUC) for MetS. However, there was no statistically significant difference in AUC between leptin and L/A, and both indices produced a significantly higher AUC than adiponectin. In conclusion, L/A and leptin may be better diagnostic markers for MetS than adiponectin. After adjusting for BMI, L/A has better ability for correctly classifying subjects with and without MetS than adiponectin or leptin alone.

Bone marrow adipocytes support dexamethasone-induced osteoclast differentiation

The purpose of this study was to examine the ability of bone marrow adipocytes to support osteoclast differentiation in vitro. The primary bone marrow adipocytes were obtained from bone marrow fluid during prosthesis insertion. NFkappa-B ligand (RANKL), Osteoprotegerin (OPG), and macrophage colony stimulating factor (M-CSF) expressions in bone marrow adipocytes with or without dexamethasone were examined. In a co-culture system with bone marrow adipocytes and osteoclast precursor cells, osteoclast differentiation was assessed by the expression of titrate-resistant acid phosphatase (TRAP) staining. RANKL, OPG, and M-CSF mRNA expressions were confirmed in all individuals. Dexamethasone significantly induced RANKL and OPG expression. The RANKL/OPG ratio was increased by dexamethasone and was significant at 10(-7) M dexamethasone. With 10(-7) M dexamethasone, osteoclast precursor cells differentiated into multinucleated TRAP-positive cells when co-cultured with bone marrow adipocytes. The present study demonstrates for the first time that bone marrow adipocytes can support osteoclast differentiation in vitro.

S26948, a new specific peroxisome proliferator activated receptor gamma modulator improved in vivo hepatic insulin sensitivity in 48 h lipid infused rats

We examined whether S26948, a new specific peroxisome proliferator activated receptor gamma modulator prevented insulin-resistance induced by a 48 h intralipid-infusion in normal rat (IL rats). The effect of S26948 (30 mg/kg) was compared to rosiglitazone (10 mg/kg). Rats were catheterized in the right jugular vein 4 days before the beginning of the 48 h lipid or saline infusions. Animals were intraperitoneally injected once daily with vehicle, S26948 or rosiglitazone. At the end of the infusion the rats underwent either a glucose tolerance test or a euglycemic-hyperinsulinemic clamp. Finally isolation and incubation of hepatocytes in another series of rats were performed. Intralipid infusion leads to a 4-fold increase in plasma free fatty acid concentration compared to controls (C). Both S26948 and rosiglitazone decreased plasma free fatty acid concentration in IL rats compared to vehicle treated IL rats. Glucose-induced insulin secretion was significantly increased in IL compared to C and was associated with insulin resistance. Both S26948 and rosiglitazone treatments normalized glucose-induced insulin secretion and improved insulin action in IL rats. However, S26948 specifically improved hepatic insulin sensitivity whereas rosiglitazone improved both hepatic insulin sensitivity and insulin-stimulated glucose utilization. Finally, studies on isolated hepatocytes showed differential effect of both compounds on gene expression of key enzymes of glucose metabolism. Our data show that non thiazolidinedione S26948 may represent an alternative way for the management of dysregulated hepatic insulin sensitivity.

Role of plasma adiponectin on the HDL-cholesterol raising effect of atorvastatin in patients with type 2 diabetes

OBJECTIVE

Adiponectin, secreted by adipose tissue, plays an important role in lipoprotein metabolism and also affects carbohydrate and insulin pathways. We studied the effects of atorvastatin treatment on plasma adiponectin and high density cholesterol (HDL) levels in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In the 'Diabetes Atorvastatin Lipid Intervention' (DALI) study, a randomized placebo-controlled study on the effects of atorvastatin treatment in 194 patients with type 2 diabetes and mildly elevated plasma triglycerides, adiponectin levels, lipoproteins, cholesteryl ester transfer protein (CETP) mass, as well as postheparin lipoprotein lipase (LPL) and hepatic lipase (HL) activities were assessed at baseline and after 6 months of treatment (placebo, 10 mg or 80 mg atorvastatin).

RESULTS

At baseline, plasma adiponectin levels were positively associated with HDL cholesterol (r = 0.40, p < 0.001), and apoA-I (r = 0.38, p < 0.001) in both males and females. Adiponectin was negatively associated with triglycerides (r = -0.26, p < 0.001) in males as well as in females. Atorvastatin treatment had no effect on plasma adiponectin levels. However, adiponectin levels at baseline significantly predicted the effect of atorvastatin treatment on HDL-cholesterol (p = 0.007), i.e. patients with the highest baseline plasma adiponectin concentration (tertile 3) displayed the largest increase in plasma HDL cholesterol during treatment (8-10%), while the HDL-cholesterol increase in tertile 1 was almost negligible (1-3%).

CONCLUSION

In this study, high baseline plasma adiponectin levels significantly affect the HDL-cholesterol response to atorvastatin treatment in patients with type 2 diabetes and therefore may play a role in defining future treatment strategy.

Adiponectin multimers and metabolic syndrome traits: relative adiponectin resistance in African Americans

African Americans (AAs) tend to have lower total adiponectin levels compared to European Americans (EA); however, it is not known whether race affects adiponectin multimer distribution and their relationships to metabolic traits. We measured total adiponectin, high molecular weight (HMW), low molecular weight (LMW) (i.e., hexamer), and trimer adiponectin in 132 normoglycemic premenopausal women (75 AAs, 57 EAs), together with measures of total and abdominal fat, plasma lipids, insulin sensitivity (S(i)), and genetic admixture estimates. We found that lower total adiponectin in AAs was explained by reduced LMW, and trimer forms because levels of HMW did not differ between races. In EAs, HMW was highly correlated with multiple metabolic syndrome traits. In contrast, the LMW and trimer forms were most highly correlated with metabolic traits in AAs, including abdominal adiposity, lipids, and S(i). At similar levels of visceral adiposity, AAs exhibited significantly lower LMW adiponectin than EAs. Similarly, at comparable levels of HMW and LMW adiponectin, AAs were more insulin resistant than their EA counterparts. In conclusion, (i) serum adiponectin is lower in AAs predominantly as a result of reduced concentrations of LMW and trimers multimeric forms; (ii) LMW and trimer, not HMW, are most broadly correlated with metabolic traits in AAs. Thus, HMW adiponectin may exert less bioactivity in explaining the metabolic syndrome trait cluster in populations of predominant African genetic background.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

Estrogen replacement therapy decreases plasma adiponectin but not resistin in postmenopausal women

The effects of estrogen replacement therapy (ERT) to cardiovascular disease risk are still unclear. Low adiponectin and high resistin plasma concentrations are reported to be associated with atherosclerosis. However, it is not known how ERT affects plasma adiponectin and resistin concentrations. Seventy-three hysterectomized, nondiabetic, postmenopausal women were randomized in a double-blind, double-dummy study to receive either peroral estradiol valerate or transdermal 17beta-estradiol gel for 6 months. Biochemical measurements were determined from samples taken before and after the therapy. Peroral estradiol valerate therapy decreased adiponectin concentrations from 13.6 to 11.6 mg/L (P = .008), whereas transdermal 17beta-estradiol gel had no effect (12.7 vs 12.2 mg/L). Neither treatment changed the resistin concentrations significantly. Plasma concentrations of estradiol and estrone did not correlate with adiponectin or resistin concentrations before or after therapy. The change in adiponectin concentration correlated significantly with the changes in waist-hip ratio, very low-density lipoprotein triglycerides, and insulin-like growth factor 1 in the peroral estradiol valerate group. The changes in these variables and the change in estradiol concentration explained 43.1% (P = .001) of the variability in the change of plasma adiponectin, the change in very low-density lipoprotein triglycerides being the strongest determinant (beta = -.407, P = .011). The results show that peroral ERT can decrease plasma adiponectin levels. However, ERT does not seem to influence plasma resistin concentrations.

Metabolic phenotypes, vascular complications, and premature deaths in a population of 4,197 patients with type 1 diabetes

OBJECTIVE

Poor glycemic control, elevated triglycerides, and albuminuria are associated with vascular complications in diabetes. However, few studies have investigated combined associations between metabolic markers, diabetic kidney disease, retinopathy, hypertension, obesity, and mortality. Here, the goal was to reveal previously undetected association patterns between clinical diagnoses and biochemistry in the FinnDiane dataset.

RESEARCH DESIGN AND METHODS

At baseline, clinical records, serum, and 24-h urine samples of 2,173 men and 2,024 women with type 1 diabetes were collected. The data were analyzed by the self-organizing map, which is an unsupervised pattern recognition algorithm that produces a two-dimensional layout of the patients based on their multivariate biochemical profiles. At follow-up, the results were compared against all-cause mortality during 6.5 years (295 deaths).

RESULTS

The highest mortality was associated with advanced kidney disease. Other risk factors included 1) a profile of insulin resistance, abdominal obesity, high cholesterol, triglycerides, and low HDL(2) cholesterol, and 2) high adiponectin and high LDL cholesterol for older patients. The highest population-adjusted risk of death was 10.1-fold (95% CI 7.3-13.1) for men and 10.7-fold (7.9-13.7) for women. Nonsignificant risk was observed for a profile with good glycemic control and high HDL(2) cholesterol and for a low cholesterol profile with a short diabetes duration.

CONCLUSIONS

The self-organizing map analysis enabled detailed risk estimates, described the associations between known risk factors and complications, and uncovered statistical patterns difficult to detect by classical methods. The results also suggest that diabetes per se, without an adverse metabolic phenotype, does not contribute to increased mortality.