Weight reduction increases plasma levels of an adipose-derived anti-inflammatory protein, adiponectin

FSH regulates fat accumulation and redistribution in aging through the Gαi/Ca(2+)/CREB pathway

Increased fat mass and fat redistribution are commonly observed in aging populations worldwide. Although decreased circulating levels of sex hormones, androgens and oestrogens have been observed, the exact mechanism of fat accumulation and redistribution during aging remains obscure. In this study, the receptor of follicle-stimulating hormone (FSH), a gonadotropin that increases sharply and persistently with aging in both males and females, is functionally expressed in human and mouse fat tissues and adipocytes. Follicle-stimulating hormone was found to promote lipid biosynthesis and lipid droplet formation; FSH could also alter the secretion of leptin and adiponectin, but not hyperplasia, in vitro and in vivo. The effects of FSH are mediated by FSH receptors coupled to the Gαi protein; as a result, Ca²⁺ influx is stimulated, cAMP-response-element-binding protein is phosphorylated, and an array of genes involved in lipid biosynthesis is activated. The present findings depict the potential of FSH receptor-mediated lipodystrophy of adipose tissues in aging. Our results also reveal the mechanism of fat accumulation and redistribution during aging of males and females.

Association of adiponectin gene polymorphism with adiponectin levels and risk for insulin resistance syndrome

Background:

Adiponectin is an abundant adipose tissue–derived protein with anti-atherogenic, anti-inflammatory and antidiabetic properties. Plasma adiponectin levels are decreased in obesity, type 2 diabetes, and coronary artery disease and low adiponectin levels also predict insulin resistance (IR).

Methods:

Case-control study in which 642 male and female subjects were participated from the North Indian population. Lipid, insulin, leptin and adiponectin level were estimated using standard protocols by commercially available test kits. Single nucleotide polymorphisms +45T>G and +276G>T of the AMP1 (adiponectin) gene was genotyped by polymerase chain reaction restriction fragment length polymorphism method.

Results:

Levels of adiponectin, insulin, homeostasis model assessment-IR index (HOMA-IR index), systolic blood pressure and fat mass showed significant differences between male and female subjects. Serum adiponectin level showed highly significant association with both the +45 and the +276 genotypes. The common haplotype triglyceride (TG) showed a significantly lower adiponectin value than other haplotypes (P = 0.0001). A clear trend of decreasing adiponectin levels per copy of the common haplotype was observed. Nonobese insulin sensitive subjects showed a higher adiponectin value (P = 0.0006) than nonobese insulin resistant subjects. The values of blood pressure, adiponectin, insulin, HOMA-IR, total-cholesterol, and low-density lipoprotein-cholesterol significantly associated with TG haplotype.

Conclusions:

We observed the very strong association of the adiponectin 45-276 genotypes and haplotypes with adiponectin levels in healthy north Indian population and TG haplotypes also associated with metabolic parameters of the IR syndrome.

A longitudinal study of the association of adiponectin gene rs1501299 with depression in Chinese Han adolescents after Wenchuan earthquake

BACKGROUND

Previous studies showed inconsistent results of the association between plasma adiponectin and depression. The aim of this study is to longitudinally investigate the association of adiponectin rs1501299 with depression in Chinese Han adolescents who experienced the 2008 Wenchuan earthquake.

METHOD

Variants of adiponectin rs1501299 were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Depressive symptoms were assessed by Beck Depression Inventory (BDI) among 746 high school students at 6, 12 and 18 months after the earthquake.

RESULTS

The female T allele carriers of adiponectin rs1501299 had lower prevalence of depression (p=0.008) and BDI scores (p=0.024) than the female GG homozygotes at 18 months, but not at 6 or 12 months after the earthquake, which were significantly reduced (p=0.022 for the prevalence and p<0.001 for the scores) in the female T allele carriers at 18 months after the earthquake when compared with those at 12 months. In addition, the major predictors of depression for the GG homozygotes were gender and age at 6, 12 and 18 months after earthquake. On the other hand, the major predictor for the T allele carriers was gender at 6, 12 and 18 months after earthquake.

LIMITATIONS

There were some limitations in the present study. First, adiponectin expressions including serum adiponectin and mRNA in adipose tissues were not measured. Second, the effect of body mass index was not evaluated.

CONCLUSIONS

The adiponectin T allele is associated with reduced prevalence of depression and lower BDI scores of female adolescents in the later stage of rehabilitation of depression.

Association of Adiponectin With Body Composition and Mortality in Hemodialysis Patients

BACKGROUND

In the general population, circulating adiponectin is associated with a favorable cardiovascular risk profile (eg, lower triglycerides and body fat) and decreased mortality. Hemodialysis (HD) patients have comparatively higher adiponectin concentrations, but prior studies examining the adiponectin-mortality association in this population have not accounted for body composition or shown a consistent relationship.

STUDY DESIGN

Prospective cohort study.

SETTINGS & PARTICIPANTS

We examined baseline serum adiponectin concentrations in 501 HD patients across 13 dialysis centers from the prospective MADRAD (Malnutrition, Diet, and Racial Disparities in Chronic Kidney Disease) cohort (entry period, October 2011 to February 2013; follow-up through August 2013).

PREDICTOR

Serum adiponectin concentration in tertiles (tertiles 1, 2, and 3 defined as ≤16.1, >16.1-<30.1, and ≥30.1-100.0 μg/mL, respectively). Adjustment variables included case-mix and laboratory test results (age, sex, race, ethnicity, vintage, diabetes, serum albumin, total iron-binding capacity, serum creatinine, white blood cell count, phosphate, hemoglobin, and normalized protein catabolic rate), body composition surrogates (subcutaneous, visceral, and total-body fat and lean body mass), and serum lipid levels (cholesterol, high-density lipoprotein cholesterol, and triglycerides).

OUTCOMES

All-cause mortality using survival (Cox) models incrementally adjusted for case-mix and laboratory test results.

RESULTS

Among 501 HD patients, 50 deaths were observed during 631.1 person-years of follow-up. In case-mix- and laboratory-adjusted Cox analyses, the highest adiponectin tertile was associated with increased mortality versus the lowest tertile (HR, 3.35; 95% CI, 1.50-7.47). These associations were robust in analyses that additionally accounted for body composition (HR, 3.18; 95% CI, 1.61-8.24) and lipid levels (HR, 3.64; 95% CI, 1.34-7.58).

LIMITATIONS

Residual confounding cannot be excluded.

CONCLUSIONS

Higher adiponectin level is associated with a 3-fold higher death risk in HD patients independent of body composition and lipid levels. Future studies are needed to elucidate underlying mechanisms and determine therapeutic targets associated with improved outcomes in HD patients.

Adiponectin as a potential biomarker of vascular disease

The increasing prevalence of diabetes and its complications heralds an alarming situation worldwide. Obesity-associated changes in circulating adiponectin concentrations have the capacity to predict insulin sensitivity and are a link between obesity and a number of vascular diseases. One obvious consequence of obesity is a decrease in circulating levels of adiponectin, which are associated with cardiovascular disorders and associated vascular comorbidities. Human and animal studies have demonstrated decreased adiponectin to be an independent risk factor for cardiovascular disease. However, in animal studies, increased circulating adiponectin alleviates obesity-induced endothelial dysfunction and hypertension, and also prevents atherosclerosis, myocardial infarction, and diabetic cardiac tissue disorders. Further, metabolism of a number of foods and medications are affected by induction of adiponectin. Adiponectin has beneficial effects on cardiovascular cells via its antidiabetic, anti-inflammatory, antioxidant, antiapoptotic, antiatherogenic, vasodilatory, and antithrombotic activity, and consequently has a favorable effect on cardiac and vascular health. Understanding the molecular mechanisms underlying the regulation of adiponectin secretion and signaling is critical for designing new therapeutic strategies. This review summarizes the recent evidence for the physiological role and clinical significance of adiponectin in vascular health, identification of the receptor and post-receptor signaling events related to the protective effects of the adiponectin system on vascular compartments, and its potential use as a target for therapeutic intervention in vascular disease.

Higher blood aldosterone level in metabolic syndrome is independently related to adiposity and fasting plasma glucose

BACKGROUND

Hypoadiponectinemia is a well-known state associated with metabolic syndrome (MetS) and insulin resistance (IR). Recently aldosterone has been highly associated with high blood pressure, and may thus be a possible biomarker for MetS and IR. In this study, we investigate the association of aldosterone with MetS and IR, and compare it with that of adiponectin.

METHODS

In this cross-sectional study, we recruited 556 women receiving physical examinations at a general hospital in central Taiwan. At the time of examination, we collected data on various demographic and physical characteristics and measured blood levels of aldosterone, adiponectin and a variety of metabolic factors. Multiple linear regression analysis was performed using adiponectin or aldosterone as the dependent variables.

RESULTS

We found an inverse correlation between blood adiponectin and aldosterone (γ = -0.11, P = 0.009). Adiponectin levels were lower and aldosterone levels higher in women with MetS that those without (8.1 ± 0.4 vs. 11.5 ± 0.2 μg/mL, P < 0.001 and 691 ± 50 vs. 560 ± 11 pmol/L, P = 0.013, respectively), as they were in women with and without IR (adiponectin 10.4 ± 0.5 vs. 11.3 ± 0.2 μg/mL, P = 0.003 and aldosterone 635 ± 31 vs. 560 ± 11 pmol/L, P = 0.022). Although aldosterone was significantly related to body fat %, fasting plasma glucose and serum creatinine levels, the relationship between adiponectin and aldosterone was not obvious after adjustment in the multivariate analysis.

CONCLUSION

Although aldosterone was related to metabolic factors, including body fat % and fasting plasma glucose in our female subjects, the relationship between aldosterone and adiponectin remains unclear.

Anti-atherogenic effect of hydrogen sulfide by over-expression of cystathionine gamma-lyase (CSE) gene

Hydrogen sulfide (H₂S) is an important gaseous signaling molecule that functions in physiological and pathological conditions, such as atherosclerosis. H₂S dilates vessels and therefore has been suggested as an anti-atherogenic molecule. Since cystathionine gamma-lyase (CSE) enzyme is responsible for producing H₂S in the cardiovascular system, we hypothesized that up-regulation of CSE expression in vivo with preservation of H₂S bioactivity can slow down plaque formation and, can serve as a therapeutic strategy against atherosclerosis. In this study, C57BL/6 wild type mice (WT), ApoE knockout mice (KO) and transgenic ApoE knockout mice overexpressing CSE (Tg/KO) at four weeks of age were weaned. They were then fed with either normal or atherogenic diet for 12 weeks. At week 16, serial plasma lipid levels, body weight, and blood pressure were measured prior to euthanization of the mice and the size of atherosclerotic plaques at their aortic roots was measured. Tg/KO mice showed an increase in endogenous H₂S production in aortic tissue, reduced atherosclerotic plaque sizes and attenuation in plasma lipid profiles. We also showed an up-regulation in plasma glutathionine peroxidase that could indicate reduced oxidative stress. Furthermore, there was an increase in expression of p-p53 and down regulation of inflammatory nuclear factor-kappa B (NF-κB) in aorta. To conclude, alteration of endogenous H₂S by CSE gene activation was associated with reduced atherosclerosis in ApoE-deficient mice. Up-regulation of CSE/H₂S pathway attenuates atherosclerosis and this would be a potential target for therapeutic intervention against its formation.

Immune and Inflammatory Signaling Pathways in Exercise and Obesity

Over the last decades the combination of both a sedentary lifestyle and excessive food availability has led to a significant increase in the prevalence of obesity, which is increasingly recognized as an important risk factor for type 2 diabetes. Several lines of evidence exist demonstrating that expanded visceral adipose tissue produces several pro-inflammatory mediators that activate signaling pathways that contribute to the development of insulin resistance. Exercise training is an important lifestyle factor that is widely used as a tool for preventing and improving lifestyle-related obesity and insulin resistance. In this regard, exercise training is useful to increase energy expenditure thereby counteracting a positive energy balance. Exercise training is also able to attenuate the activation of several obesity-induced pathways of inflammation and oxidative stress. Thus, a better understanding of the molecular mechanisms and immune pathways in exercise, obesity, and diabetes can be extremely useful to exploit optimized lifestyle strategies to combat the increasing incidence of metabolic diseases.

Short-term melatonin consumption protects the heart of obese rats independent of body weight change and visceral adiposity

Chronic melatonin treatment has been shown to prevent the harmful effects of diet-induced obesity and reduce myocardial susceptibility to ischaemia-reperfusion injury (IRI). However, the exact mechanism whereby it exerts its beneficial actions on the heart in obesity/insulin resistance remains unknown. Herein, we investigated the effects of relatively short-term melatonin treatment on the heart in a rat model of diet-induced obesity. Control and diet-induced obese Wistar rats (fed a high calorie diet for 20 wk) were each subdivided into three groups receiving drinking water with or without melatonin (4 mg/kg/day) for the last 6 or 3 wk of experimentation. A number of isolated hearts were perfused in the working mode, subjected to regional or global ischaemia-reperfusion; others were nonperfused. Metabolic parameters, myocardial infarct sizes (IFS), baseline and postischaemic activation of PKB/Akt, ERK42/44, GSK-3β and STAT-3 were determined. Diet-induced obesity caused increases in body weight gain, visceral adiposity, fasting blood glucose, serum insulin and triglyceride (TG) levels with a concomitant cardiac hypertrophy, large postischaemic myocardial IFSs and a reduced cardiac output. Melatonin treatment (3 and 6 wk) decreased serum insulin levels and the HOMA index (P < 0.05) with no effect on weight gain (after 3 wk), visceral adiposity, serum TG and glucose levels. It increased serum adiponectin levels, reduced myocardial IFSs in both groups and activated baseline myocardial STAT-3 and PKB/Akt, ERK42/44 and GSK-3β during reperfusion. Overall, short-term melatonin administration to obese/insulin resistant rats reduced insulin resistance and protected the heart against ex vivo myocardial IRI independently of body weight change and visceral adiposity.

Understanding androgen action in adipose tissue

Androgens play an important role in regulation of body fat distribution in humans. They exert direct effects on adipocyte differentiation in a depot-specific manner, via the androgen receptor (AR), leading to modulation of adipocyte size and fat compartment expansion. Androgens also impact directly on key adipocyte functions including insulin signalling, lipid metabolism, fatty acid uptake and adipokine production. Androgen excess and deficiency have implications for metabolic health in both males and females, and these metabolic effects may be mediated through adipose tissue via effects on fat distribution, adipocyte function and lipolysis. Research into the field of androgen metabolism in human and animal adipose tissue has produced inconsistent results; it is important to take into account the sex-, depot- and organism-specific effects of androgens in fat. In general, studies point towards a stimulatory effect on lipolysis, with impairment of adipocyte differentiation, insulin signalling and adipokine generation. Observed effects are frequently gender-specific. Adipose tissue is an important organ of pre-receptor androgen metabolism, through which local androgen availability is rigorously controlled. Adipose androgen exposure is tightly controlled by isoenzymes of AKR1C, 5α-reductase and others, but regulation of the balance between generation and irreversible inactivation remains poorly understood. In particular, AKR1C2 and AKR1C3 are crucial in the regulation of local androgen bioavailability within adipose tissue. These isoforms control the balance between activation of androstenedione (A) to testosterone (T) by the 17β-hydroxysteroid dehydrogenase activity (17β-HSD) of AKR1C3, or inactivation of 5α-dihydrotestosterone (DHT) to 5α-androstane-3α,17β-diol by the 3α-hydroxysteroid dehydrogenase (3α-HSD) activity of AKR1C2. Most studies suggest that androgen inactivation is the predominant reaction in fat, particularly in the abdominal subcutaneous (SC) depot. Modulation of local adipose androgen availability may afford future therapeutic options to improve metabolic phenotype in disorders of androgen excess and deficiency.

Electroacupuncture decreases the leukocyte infiltration to white adipose tissue and attenuates inflammatory response in high fat diet-induced obesity rats

Suppression of white adipose tissue inflammatory signaling may contribute to the pathogenesis of obesity-induced inflammatory response. However, the precise mechanism of efficacy of acupuncture related to adipose tissue remains poorly understood. In the present study we evaluated the anti-inflammatory activities of 10 Hz electroacupuncture (EA) which was applied at the acupoint Zusanli (ST36) for 20 min per day in high-fat diet- (HFD-) induced obesity model. Treatment lasted for one week. Obese rats treated with EA showed significantly reduced body weight compared with the rats in HFD group. EA decreased the number of F4/80 and CD11b-positive macrophages in epididymal adipose tissue. We found that 10 Hz EA given 7 days/week at ST36 acupoints significantly alleviated macrophage recruitment and then improved the obesity-associated factors of sterol regulatory element-binding protein-1 (SREBP-1) and target genes expression in rats with HFD. Adipose tissue inflammatory responses indicated by tumor necrosis factor-α (TNF-α), IL-6, monocyte chemotactic protein-1 (MCP-1), and CD68 mRNA expression were significantly reduced by EA in obese rats. Additionally, EA was found to significantly reduced serum levels of TNF-α, IL-6, and IL-1 in this model. These results indicated that EA improved adipose tissue inflammatory response in obese rats, at least partly, via attenuation of lipogenesis signaling.

Comparison of serum maternal adiponectin concentrations in women with isolated intrauterine growth retardation and intrauterine growth retardation concomitant with pre-eclampsia

OBJECTIVE

The aim of this study was to compare serum maternal adiponectin concentrations in pregnant women with isolated intrauterine growth retardation (IUGR) and in pregnant women with IUGR concomitant with pre-eclampsia (IUGRcwPE).

MATERIAL AND METHODS

Thirty patients with isolated IUGR (group 1), 20 patients with IUGRcwPE (group 2), and 30 healthy controls (group 3) between age 18-40 were included into the study. Venous blood samples of those patients were obtained in the starving state. Adiponectin concentrations were measured by enzyme-linked immunosorbent assay in serum obtained after centrifugation. To find the differences between the groups, student t-test and one-way ANOVA statistical methods were used.

RESULTS

There were no differences between the groups in terms of age, body mass index, gestational age, and parity (p>0.05). The values of amniotic fluid index (p<0.001) and weight gained during pregnancy (p=0.017) were significantly different when compared among the three groups. The mean concentrations of adiponectin were 94.041 pg/mL in the IUGR group, 55.717 pg/mL in the IUGRcwPE group, and 51.831 pg/mL in the control group. Both of the differences between the IUGR and IUGRcwPE groups (p value; <0.05) and IUGR and control groups were statistically significant (p value; <0.001). However, there were no significant differences between the IUGRcwPE group and control group (p>0.05).

CONCLUSION

We found that IUGR increased maternal serum adiponectin concentrations; however, this rise does not occur in pregnant women with IUGRcwPE.

Increased Hs-CRP/adiponectin ratio is associated with increase carotid intima-media thickness

BACKGROUND

High sensitivity C-reactive protein (Hs-CRP) and adiponectin (APN) are two critical cytokines and exert inverse effects on atherosclerosis initiation and progression. The purpose of our study was to investigate the value of Hs-CRP and ANP ratio (Hs-CRP/APN ratio) on evaluating atherosclerosis progression.

METHOD

One hundred sixty consecutive participants underwent carotid intima-media thickness (CIMT) measured by ultrasound were enrolled and drawn fasting blood samples for plasma levels Hs-CRP and APN, serum levels of lipid profiles and fasting blood glucose evaluation. Other anthropometrics and clinical status were collected by questionnaire. All participants were divided into 4 groups according to the baseline Hs-CRP/APN ratio and underwent CIMT measurement every 6 months. CIMT increment and composite cardiovascular endpoints were compared after 24 months' follow-up.

RESULTS

At baseline, body mass index (BMI), smoking, diabetic mellitus, usage of statins, Hs-CRP and APN independently correlated with Hs-CRP/APN ratio as analyzed by spearman rank correlation. Smoking, serum level of LDL-C, plasma level of Hs-CRP and Hs-CRP/APN ratio were positively correlated with CIMT while usage of statins and plasma level of APN were negatively correlated with CIMT as analyzed by multiple linear regression analysis. After 24 months' follow-up, the progression of CIMT was the most prominent in the fourth quartile of baseline Hs-CRP/APN ratio. In addition, the incidence of composite cardiovascular endpoint was also higher in the fourth quartile as compared to the other 3 lower quartiles.

CONCLUSION

Hs-CRP/APN ratio was a useful predictor to discriminate subjects who were at increased risk of atherosclerosis progression.

Secreted adiponectin as a marker to evaluate in vitro the adipogenic differentiation of human mesenchymal stromal cells

BACKGROUND AIMS

Multipotency is one of the hallmarks of mesenchymal stromal cells (MSCs). Given the widespread adoption of MSC-based clinical applications, the need for rapid and reliable methods to estimate MSC multipotency is demanding. Adipogenic potential is commonly evaluated by staining cell lipid droplets with oil red O. This cytochemical assay is performed at the terminal stage of adipogenic induction (21-28 days) and necessitates the destruction of the specimen. In this study, we investigated whether it is possible to assess MSC adipogenic differentiation in a more efficient, timely and non-destructive manner, while monitoring in vitro secretion of adiponectin, a hormone specifically secreted by adipose tissue.

METHODS

A commercially available enzyme-linked immunosorbent assay kit was used to quantify adiponectin secreted in the culture medium of adipo-induced human bone marrow-derived MSCs. Oil red O staining was used as a reference method.

RESULTS

Adiponectin is detectable after 10 days of induction at a median concentration of 5.13 ng/mL. The secretion of adiponectin steadily increases as adipogenesis proceeds. Adiponectin is undetectable when adipogenic induction is pharmacologically blocked, inefficient or when human MSCs are induced to differentiate toward the osteogenic lineage, proving the specificity of the assay. Furthermore, the results of adiponectin secretion strongly correlate with oil red O quantification at the end of induction treatment.

CONCLUSIONS

Our results demonstrate that quantification of secreted adiponectin can be used as a reliable and robust method to evaluate adipogenic potential without destroying samples. This method provides a useful tool for quality control in the laboratory and in clinical applications of human MSCs.

Plasma adipokines and risk of hepatocellular carcinoma in chronic hepatitis B virus-infected carriers: a prospective study in taiwan

BACKGROUND

Obesity is considered a risk factor for hepatocellular carcinoma (HCC). The relationship between adipocytokine and HCC in hepatitis B virus (HBV) carriers remains unclear. We prospectively investigated the association of adiponectin, leptin, and visfatin levels with HCC.

METHODS

We conducted a nested case-control study in a community-based cohort with 187 incident HCC and 374 HCC-free HBV carriers. Unconditional logistic regression was conducted to estimate the ORs and 95% confidence intervals (CI).

RESULTS

Adiponectin, but not leptin and visfatin, levels were associated with an increased risk of HCC after adjustment for other metabolic factors and HBV-related factors. The risk was increased [OR = 0.51; 95% CI, 0.12-2.11; OR = 4.88 (1.46-16.3); OR = 3.79 (1.10-13.0); OR = 4.13 (1.13-15.1) with each additional quintiles, respectively] with a significant dose-response trend (P(trend) = 0.003). HCC risk associated with higher adiponectin level was higher in HBV carriers with ultrasonographic fatty liver, genotype C infection, higher viral load, and with elevated alanine aminotransferase. Longitudinally, participants with higher adiponectin were less likely to achieve surface antigen of hepatitis B virus (HBsAg) seroclearance and more likely to have persistently higher HBV DNA. Eventually, they were more likely to develop liver cirrhosis [OR = 1.65 (0.62-4.39); OR = 3.85 (1.47-10.1); OR = 2.56 (0.96-6.84); OR = 3.76 (1.33-10.7) for the second, third, fourth, and fifth quintiles, respectively; P(trend) = 0.017] before HCC.

CONCLUSIONS

Elevated adiponectin levels were independently associated with an increased risk of HCC.

IMPACT

Adiponectin may play different roles in the virus-induced and metabolic-related liver diseases, but the underlying mechanism remains unknown.

Early life adversity is associated with elevated levels of circulating leptin, irisin, and decreased levels of adiponectin in midlife adults

CONTEXT

Early-life adversity, defined as physical, emotional, or sexual abuse and neglect before 18 years of age, is associated with metabolic syndrome, obesity, and type 2 diabetes mellitus in adult life. However, the underlying mechanism is not fully understood, and whether adipomyokines are associated with early-life adversity independent of other factors such as body mass index, psychosocial risks, and health behaviors is not known.

OBJECTIVES

The objective of the study was to evaluate the association between early-life adversity and circulating the levels of the adipomyokines such as leptin, adiponectin, and irisin and the inflammatory marker, C-reactive protein (CRP). DESIGN/SUBJECTS/SETTING: This study was a cross-sectional study of 95 adults at a university-based research center. We collected venous blood from participants and analyzed serum for leptin, adiponectin, irisin, and CRP.

RESULTS

Circulating leptin, irisin, and CRP levels were significantly higher in the highest adversity tertile group compared with low and middle tertile groups (P < .001 for leptin, P = .01 for irisin, and P = .02 for CRP). Adiponectin levels were lower in the highest tertile group compared with the low and middle tertile groups (P = .03). After adjusting for demographic variables, physical activity, diet, current mental health, and body mass index, the associations between early-life adversity leptin, irisin, and did not change. However, adiponectin and CRP levels were no longer significantly related to early life adversity.

CONCLUSION

Early-life adversity is directly associated with elevated circulating leptin and irisin, and indirectly associated with elevated CRP and decreased adiponectin. These findings suggest that these adipomyokines may play a role in the pathogenesis of metabolic abnormality in a population with significant early life adversity.

Assembly of adiponectin oligomers

Adiponectin is among the most studied adipokines, the collection of molecules secreted from adipose tissue. It is also one of the most architecturally complex adipokines with its various oligomeric states that include trimers, hexamers, nonamers (9mers), dodecamers (12mers), and octadecamers (18mers). The importance of adiponectin in metabolic regulation is underscored by its strong positive associations with improvement in insulin action and also decreased risks for developing type 2 diabetes. Understanding the mechanisms involved in maintaining the steady-state concentrations of adiponectin oligomers in circulation is therefore likely to provide important insight into the development of insulin resistance. This review will discuss the current state of knowledge regarding the biochemical composition of adiponectin oligomers, the commonly used techniques to analyze them, and the known post-translational modifications that affect their assembly. Evidence based on in vitro oligomer assembly reactions in support of a "cystine ratchet" model of adiponectin oligomer formation will be considered along with limitations of the evidence. Secretory pathway proteins that have been shown to affect the distribution of adiponectin oligomers will also be discussed along with hypotheses regarding their potential involvement in the cystine ratchet model of adiponectin oligomerization.

Histidine supplementation alleviates inflammation in the adipose tissue of high-fat diet-induced obese rats via the NF-κB- and PPARγ-involved pathways

Obesity is considered to be accompanied by a chronic low-grade inflammatory state that contributes to the occurrence of many chronic diseases. Our previous study has demonstrated that histidine supplementation significantly ameliorates inflammation and oxidative stress in obese women. However, the in vivo potential mechanisms are not known. The present study was conducted to investigate the mechanisms underlying the effects of histidine on inflammation in a high-fat diet (HFD)-induced female obese rat model. An obese model was established in female Sprague–Dawley rats by HFD feeding for 8 weeks and followed by histidine supplementation for another 4 weeks. The results revealed that HFD-increased body weight and HFD-lowered serum histidine concentrations were significantly reversed by histidine supplementation (P< 0·05). In addition, the serum concentrations of TNF-α, IL-6, C-reactive protein (CRP) and malondialdehyde were significantly reduced and those of superoxide dismutase (SOD) were significantly increased by histidine supplementation when compared with those in obese rats (P< 0·05). Correspondingly, the mRNA expressions of TNF-α, IL-6 and CRP in the adipose tissue were significantly down-regulated and that of CuZnSOD was significantly up-regulated by histidine supplementation (P< 0·05). Histidine supplementation significantly reduced the HFD-induced translocation of NF-κB p65 into the nucleus (P= 0·032) by reducing the phosphorylation of the inhibitor of κBα in the adipose tissue. The results also revealed that the expression of adiponectin was markedly increased both in the serum and in the adipose tissue after histidine supplementation, accompanied by the activation of PPARγ (P= 0·021). These findings indicate that histidine is an effective candidate for ameliorating inflammation and oxidative stress in obese individuals via the NF-κB- and PPARγ-involved pathways.

Weight loss is more important than the diet type in improving adiponectin levels among overweight/obese adults

OBJECTIVE

The study objective was to compare the effect of a standard calorie- and fat-restricted diet (STD-D) and a calorie- and fat-restricted lacto-ovo-vegetarian diet (LOV-D) on total and high-molecular-weight (HMW) adiponectin levels after 6 months of behavioral intervention.

DESIGN

This study is an ancillary study to a randomized clinical trial.

SUBJECTS

Subjects included 143 overweight/obese adults (STD-D = 79; LOV-D = 64).

INTERVENTION

Both groups received the same standard behavioral intervention; the only difference was that LOV-D participants were instructed to eliminate meat, poultry, and fish from their diet.

MEASURES

Weight, dietary intake with the 3-day food diary, and total and HMW adiponectin levels were measured.

RESULTS

Both groups significantly increased total (STD-D +7.2 ± 17.8%; LOV-D +9.4 ± 21.8%) and HMW adiponectin levels (STD-D +18.5 ± 32.9%; LOV-D +15.8 ± 34.5%; ps < 0.05) with no significant differences between the groups. We found significant associations between weight loss and increases in total (β (SE) = -.071(.27); p = 0.003) and HMW adiponectin (β (SE) = -1.37(.47); p = 0.001) levels independent of the diet type. Weight loss at the higher quartile was associated with improvements of adiponectin levels (p < 0.05).

CONCLUSION

Weight loss was associated with increased total and HMW adiponectin levels regardless of the diet type. Enhancing weight loss may be a means to improve adiponectin levels.

Adiponectin serum concentrations in newborn at delivery appear to be of fetal origin

OBJECTIVE

Adiponectin (APN) may play a role in adapting energy metabolism at the maternal-fetal unit. The aim of the study was to investigate the relationship between placental APN mRNA expression, maternal serum APN concentration and umbilical cord serum APN concentration in full-term healthy newborns.

METHODS

Serum APN levels were compared in 46 samples (23 from healthy newborns; gestational age 37.0 to 41.5 weeks) and their mothers (n=23). The APN concentration was measured using enzyme linked immunosorbent assay (ELISA). We analyzed the mRNA expression profile of APN in 22 placenta tissue samples using real time polymerase chain reaction (RT-PCR).

RESULTS

The highest APN serum concentrations were found in umbilical cord blood, these were significantly higher than maternal APN levels (mean concentration±SD; 38.48±12.8 vs. 6.6±2.3 μg/mL, p<0.001). Otherwise, there were no significant correlation between maternal APN and umbilical cord APN concentration. APN gene expression was very low and only found in 8 out of 22 placentas. There were no significant correlation between placental APN mRNA and umbilical cord serum APN or maternal serum APN concentration. Umbilical cord APN concentrations were positively associated with birth weight (r=0.535; p=0.012) and gestational age (r=0.559; p=0.013). Maternal APN concentration revealed a negative correlation between maternal body weight (r=-0.623; p=0.009) and body mass index (BMI) (r=-0.634; p=0.008) at delivery. Additionally, no significant correlation was found between newborn birth weight and maternal weight.

CONCLUSIONS

This study suggests that high serum APN concentrations in umbilical cord blood are not regulated by placental APN mRNA gene expression. The high concentration of APN in cord blood is independent from maternal APN concentration, suggesting an important physiological role of APN and implicating that umbilical APN concentration reflects its exclusive production by fetal tissues.

Effects of exercise on C-reactive protein, inflammatory cytokine and adipokine in patients with type 2 diabetes: a meta-analysis of randomized controlled trials

OBJECTIVE

C-reactive protein (CRP), inflammatory cytokines, and adipokines contribute to atherosclerosis, insulin resistance, and development of late-onset complication in patients with type 2 diabetes. We performed a systematic review to assess effects of exercise interventions on inflammatory markers/cytokines and adipokines.

MATERIALS/METHODS

We searched electronic databases (MEDLINE, EMBASE, and Cochrane Controlled Trials Registry) and reference lists in relevant papers for articles published in 1966-2013. We selected studies that evaluated the effects of exercise intervention on inflammatory markers/cytokines and adipokines in adult patients with type 2 diabetes. Weighted mean differences of exercise on outcomes were derived using fixed or random effect models; factors influencing heterogeneity were identified using meta-regression analysis.

RESULTS

Fourteen randomized controlled trials (824 patients) were included in our meta-analysis. Exercise was associated with a significant in CRP=-0.66mg/l (95% CI, -1.09 to -0.23mg/l; -14% from baseline) and interleukin-6 (IL-6)=-0.88pg/ml (95% CI, -1.44 to -0.32pg/ml; -18% from baseline) but did not alter adiponectin or resistin levels; aerobic exercise program was associated with a significant change in leptin=-3.72ng/ml (95% CI, -6.26 to -1.18ng/ml; -24% from baseline). For IL-6, exercise was more effective in those with a longer duration in the program and larger number of sessions during study (p=0.001).

CONCLUSIONS

Exercise decreases inflammatory cytokine (CRP and IL-6) in patients with type 2 diabetes. Exercise could be a therapeutic option for improving abnormalities in inflammation levels in patients with diabetes.

Association between adiponectin and cartilage degradation in human osteoarthritis

OBJECTIVE

Conflicting findings raise questions about the role of adiponectin in osteoarthritis (OA). The current study aimed to investigate in OA patients the association between the production of adiponectin and the grade of cartilage destruction, and to provide functional evidence for a potential role of adiponectin in OA.

DESIGN

The expression of adiponectin was examined by immunohistochemistry in cartilage obtained from healthy individuals (n = 2; ages 56 and 41 years; 1 male and 1 female) and OA patients (n = 11; ages 64-79 years; 2 male and 9 female). The association between its production in chondrocytes and the grade of cartilage destruction was established on full-depth cartilage biopsies. The functional activity of adiponectin in OA cartilage was determined from the relation between the expression of adiponectin, its receptor, cartilage-specific components and factors involved in matrix degradation, and from the chondrocyte response to the full-length or the globular form of adiponectin.

RESULTS

Adiponectin was not detected in healthy cartilage. Conversely, the adipokine was up-regulated in damaged tissue, but no strong association with the grade of cartilage destruction was found. We showed a positive correlation between adiponectin and mPGES or MMP-13 while AdipoR1 was related to the expression of type 2 collagen, aggrecan and Sox9. The full-length form of adiponectin but not the globular isoform, stimulated the production of PGE2 and MMP-13 activity in cultured human chondrocytes.

CONCLUSIONS

The elevated level of adiponectin found in chondrocytes from OA patients might contribute to matrix remodelling during OA, the full-length isoform being the single active form.

Vaspin inhibited proinflammatory cytokine induced activation of nuclear factor-kappa B and its downstream molecules in human endothelial EA.hy926 cells

AIMS

In this study, we investigated the effects of visceral adipose tissue-derived serpin (vaspin), a newly discovered adipocytokine, on nuclear factor-kappa B (NF-κB) and its downstream molecules in proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukine-1 (IL-1), stimulated human endothelial EA.hy926 cells to elucidate the role of vaspin in the inflammatory states of endothelium.

METHODS

A NF-κB luciferase reporter system was constructed and stably transfected into human endothelial cell line EA.hy926. Following transfection, EA.hy926 cells were pretreated with various concentrations of vaspin (0-320 ng/ml) before TNF-α and IL-1 stimulation. The transcription activity of NF-κB was determined using luciferase reporter assay. Expression levels of NF-κB downstream inflammatory cytokines, TNF-α, IL-1 and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA). Expressions of adhesion molecules and chemokines, intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemotactic protein-1 (MCP-1) were determined by quantitative real-time PCR (RT-PCR) and western blot in mRNA and protein levels, respectively.

RESULTS

Results showed that vaspin inhibited TNF-α and IL-1 mediated activation of NF-κB and its downstream molecules in a concentration-dependent manner (P<0.05).

CONCLUSIONS

We conclude that vaspin protected endothelial cells from proinflammatory cytokines induced inflammation by inhibition of NF-κB and its downstream molecules.

Visceral adipose tissue is significantly associated with hearing thresholds in adult women

OBJECTIVE

Metabolic syndrome is a risk factor for age-related hearing impairment (ARHI). There are metabolic differences between abdominal adipose tissue present in subcutaneous and visceral areas. In this study, we investigated the association between abdominal fat composition, measured by computerized tomography (CT), and hearing thresholds.

PATIENTS AND METHODS

We recruited 662 adults aged 40-82 years with normal or symmetrical sensorineural hearing loss who underwent fat measurement by CT. Linear regression models were used to address the association between risk factors, including abdominal fat composition, and average hearing levels at low and high frequencies.

RESULTS

After adjusting for age, systemic disease and other variables, a positive association between visceral adipose tissue (VAT) area and average hearing threshold was observed in women. In men, there was no significant association between abdominal fat composition and hearing threshold.

CONCLUSION

Our findings show an association between VAT and hearing impairment in women. A reduction in visceral adiposity may help to prevent hearing loss in women.

Roles of adiponectin and oxidative stress in obesity-associated metabolic and cardiovascular diseases

The recent increase in populations with obesity is a worldwide social problem, and the enhanced susceptibility of obese people to metabolic and cardiovascular diseases has become a growing health threat. An understanding of the molecular basis for obesity-associated disease development is required to prevent these diseases. Many studies have revealed that the mechanism involves various bioactive molecules that are released from adipose tissues and designated as adipocytokines/adipokines. Adiponectin is an adipocytokine that exerts insulin-sensitizing effects in the liver and skeletal muscle via adenosine monophosphate-activated protein kinase and proliferator-activated receptor α activation. Additionally, adiponectin can suppress atherosclerosis development in vascular walls via various anti-inflammatory effects. In contrast, oxidative stress is a harmful factor that systemically increases during obesity and promotes the development of diabetes, atherosclerosis, and various other diseases. In obese mice, oxidative stress is enhanced in adipose tissue before diabetes development, but not in the liver, skeletal muscle, and aorta, suggesting that in obesity, adipose tissue may be a major source of reactive oxygen species (ROS). ROS suppress adiponectin production in adipocytes. Treatment of obese mice with anti-oxidative agents improves insulin resistance and restores adiponectin production. Recent studies have demonstrated that adiponectin protects against oxidative stress-induced damage in the vascular endothelium and myocardium. Thus, decreased circulating adiponectin levels and increased oxidative stress, which are closely linked to each other, should be deeply involved in obesity-associated metabolic and cardiovascular disease pathogenesis.

Modulation of adiponectin as a potential therapeutic strategy

Adiponectin is produced predominantly by adipocytes and plays an important role in metabolic and cardiovascular homeostasis through its insulin-sensitizing actions and anti-inflammatory and anti-atherogenic properties. Recently, it has been observed that lower levels of adiponectin can substantially increase the risk of developing type 2 diabetes, metabolic syndrome, atherosclerosis, and cardiovascular disease in patients who are obese. Circulating adiponectin levels are inversely related to the inflammatory process, oxidative stress, and metabolic dysregulation. Intensive lifestyle modifications and pharmacologic agents, including peroxisome proliferator-activated receptor-γ or α agonists, some statins, renin-angiotensin-aldosterone system blockers, some calcium channel blockers, mineralocorticoid receptor blockers, new β-blockers, and several natural compounds can increase adiponectin levels and suppress or prevent disease initiation or progression, respectively, in cardiovascular and metabolic disorders. Therefore, it is important for investigators to have a thorough understanding of the interventions that can modulate adiponectin. Such knowledge may lead to new therapeutic approaches for diseases such as type 2 diabetes, metabolic syndrome, cardiovascular disease, and obesity. This review focuses on recent updates regarding therapeutic interventions that might modulate adiponectin.

Leptin gene promoter DNA methylation in WNIN obese mutant rats

BACKGROUND

Obesity has become an epidemic in worldwide population. Leptin gene defect could be one of the causes for obesity. Two mutant obese rats WNIN/Ob and WNIN/GROb, isolated at National Centre for Laboratory Animal Sciences (NCLAS), Hyderabad, India, were found to be leptin resistant. The present study aims to understand the regulatory mechanisms underlying the resistance by promoter DNA methylation of leptin gene in these mutant obese rats.

METHODS

Male obese mutant homozygous, carrier and heterozygous rats of WNIN/Ob and WNIN/GROb strain of 6 months old were studied to check the leptin gene expression (RT-PCR) and promoter DNA methylation (MassARRAY Compact system, SEQUENOM) of leptin gene by invivo and insilico approach.

RESULTS

Homozygous WNIN/Ob and WNIN/GROb showed significantly higher leptin gene expression compared to carrier and lean counterparts. Leptin gene promoter DNA sequence region was analyzed ranging from transcription start site (TSS) to-550 bp length and found four CpGs in this sequence among them only three CpG loci (-309, -481, -502) were methylated in these WNIN mutant rat phenotypes.

CONCLUSION

The increased percentage of methylation in WNIN mutant lean and carrier phenotypes is positively correlated with transcription levels. Thus genetic variation may have effect on methylation percentages and subsequently on the regulation of leptin gene expression which may lead to obesity in these obese mutant rat strains.

Gender differences in adiponectin levels and body composition in older adults: Hallym aging study

Background

Body composition changes with ageing can influence the adiponectin concentration. However, the component of body composition that is associated with adiponectin concentrations in older adults remains unclear.

Methods

There were 152 males and 168 females aged 65 years or older that participated in the 2010 Hallym Aging Study (HAS). Body composition (assessed by dual energy X-ray absorptiometry; DXA), anthropometric parameters and adiponectin were obtained from all participants. Multivariate linear regression models assessed the association of body fat percentage, regional muscle and bone mineral contents of body composition and waist/height ratio with adiponectin concentration. Age, albumin, testosterone concentration and metabolic parameters were considered as confounding factors.

Results

In correlation analysis, age was positively associated with adiponectin in males (P < 0.01), but not in females. Fasting glucose, albumin, arm skeletal muscle mass and bone mineral content were negatively associated with adiponectin in males (P < 0.05). Testosterone and leg bone mineral content were negatively associated with adiponectin in females (P < 0.05). In multivariate linear regression models, body fat percentage and albumin (P < 0.05) were negatively associated with adiponectin, and high-density lipoprotein cholesterol (HDL-C) (P < 0.001) and age (P < 0.01) were positively associated with adiponectin in older males. In older females, the only factors that correlated significantly with adiponectin concentration were the homeostasis model assessment of insulin resistance (P < 0.001) and HDL-C (P < 0.05). The waist/height ratio and bone mineral content were not associated with adiponectin in either gender.

Conclusion

Plasma adiponectin levels correlated negatively with body fat percentage in older males but not in older females. The differential results between older males and females suggest that certain gender-specific mechanisms may affect the association between adiponectin and age-related body composition changes.

Adiponectin as a biomarker of osteoporosis in postmenopausal women: controversies

The literature reports indicating a link between plasma levels of adiponectin and body fat, bone mineral density, sex hormones, and peri- and postmenopausal changes, draw attention to the possible use of adiponectin as an indicator of osteoporotic changes, suggesting that adiponectin may also modulate bone metabolism. In this study, we attempted to analyze the available in vitro and in vivo results which could verify this hypothesis. Although several studies have shown that adiponectin has an adverse effect on bone mass, mainly by intensifying resorption, this peptide has also been demonstrated to increase the proliferation and differentiation of osteoblasts, inhibit the activity of osteoclasts, and reduce bone resorption. There are still many ambiguities; for example, it can be assumed that concentrations of adiponectin in plasma do not satisfactorily reflect its production by adipose tissue, as well as conflicting in vitro and in vivo results. It seems that the potential benefit in the treatment of patients with osteoporosis associated with the pharmacological regulation of adiponectin is controversial.

Ethanol extract of lotus (Nelumbo nucifera) root exhibits an anti-adipogenic effect in human pre-adipocytes and anti-obesity and anti-oxidant effects in rats fed a high-fat diet

Lotus (Nelumbo Nucifera) root, a well-known medicinal plant in Asia, is reported to have various therapeutic benefits, including anti-diabetes, anti-hypertension, and anti-hyperlipidaemia. We hypothesized that the ethanol extract of lotus root (ELR) would exhibit an anti-adipogenic effect in human pre-adipocytes as well as anti-obesity and anti-oxidant effects in rats fed a high-fat diet. Treatment with ELR in human pre-adipocytes resulted in inhibition of lipid accumulation and attenuated expression of adipogenic transcription factors such as peroxisome proliferator-activated receptor gamma and adipocyte marker genes, such as glucose transporter 4 and leptin. Administration of ELR resulted in a significant decrease in relative weights of adipose tissues in rats fed a high-fat diet. Consumption of a high-fat diet resulted in an increase in serum total cholesterol (TC) and triglyceride (TG) levels; however, administration of ELR resulted in a decrease in the levels of TC and TG. Administration of ELR resulted in a decrease in the level of serum leptin and insulin. Administration of ELR in rats fed a high-fat diet resulted in a decrease in hepatic thiobarbituric acid reactive substance content, elevated by a high-fat diet and an increase in superoxide dismutase activity and hepatic glutathione content. These results suggest that lotus root exerts anti-oxidant and anti-obesity effects and could be used as a functional and nutraceutical ingredient in combatting obesity-related diseases.

Lifestyle modification and endothelial function in obese subjects

The metabolic syndrome is a cluster of metabolic and vascular abnormalities that include central obesity, insulin resistance, hyperinsulinemia, glucose intolerance, hypertension, dyslipidemia, hypercoagulability and an increased risk of coronary and cerebral vascular disease. These metabolic and vascular abnormalities are the main cause of cardiovascular mortality in western societies. Endothelial dysfunction, an early step in the development of atherosclerosis, has been reported in obese nondiabetic individuals and in patients with Type 2 diabetes. It has also been observed in individuals at high risk for Type 2 diabetes, including those with impaired glucose tolerance and the normoglycemic first-degree relatives of Type 2 diabetic patients. Recent evidence points to adipocytes as a complex and active endocrine tissue whose secretory products, including free fatty acids and several cytokines (i.e., leptin, adiponectin, tissue necrosis factor-alpha, interleukin-6, and resistin) play a major role in the regulation of human metabolic and vascular biology. These adipocytokines have been claimed to be the missing link between insulin resistance and cardiovascular disease. Interventions designed to improve endothelial and/or adipose-tissue functions may reduce cardiovascular events in obese individuals with either the metabolic syndrome or Type 2 diabetes. Lifestyle modification in the form of caloric restriction and increased physical activity are the most common modalities used for treating those individuals at risk and is unanimously agreed to be the initial step in managing Type 2 diabetes. Several recent studies have demonstrated favorable impacts of lifestyle modifications in improving endothelial function and insulin sensitivity, in addition to altering serum levels of adipocytokines and possibly reducing cardiovascular events. This review discusses current knowledge of the role of lifestyle modifications in ameliorating cardiovascular risk in obese subjects with either the metabolic syndrome or Type 2 diabetes.

Genetic Variations in the Kir6.2 Subunit (KCNJ11) of Pancreatic ATP-Sensitive Potassium Channel Gene Are Associated with Insulin Response to Glucose Loading and Early Onset of Type 2 Diabetes in Childhood and Adolescence in Taiwan

To investigate the role of E23K polymorphism of the KCNJ11 gene on early onset of type 2 diabetes in school-aged children/adolescents in Taiwan, we recruited 38 subjects with type 2 diabetes (ages 18.6 ± 6.6 years; body mass index percentiles 83.3 ± 15.4) and 69 normal controls (ages 17.3 ± 3.8 years; body mass index percentiles 56.7 ± 29.0) from a national surveillance for childhood/adolescent diabetes in Taiwan. We searched for the E23K polymorphism of the KCNJ11 gene. We found that type 2 diabetic subjects had higher carrier rate of E23K polymorphism of KCNJ11 gene than control subjects (P = 0.044). After adjusting for age, gender, body mass index percentiles, and fasting plasma insulin, the E23K polymorphism contributed to an increased risk for type 2 diabetes (P = 0.047). K23-allele-containing genotypes conferring increased plasma insulin level during OGTT in normal subjects. However, the diabetic subjects with the K23-allele-containing genotypes had lower fasting plasma insulin levels after adjustment of age and BMI percentiles. In conclusion, the E23K variant of the KCNJ11 gene conferred higher susceptibility to type 2 diabetes in children/adolescents. Furthermore, in normal glucose-tolerant children/adolescents, K23 allele carriers had a higher insulin response to oral glucose loading.

Effects of fenofibrate on adiponectin expression in retinas of streptozotocin-induced diabetic rats

Adiponectin has been associated with increased risks of microvascular complications in diabetes; however, its role in the development of diabetic retinopathy (DR) is unknown. Fenofibrate is a lipid-lowering agent that has been shown to be capable of preventing DR progression. We investigated the expression of adiponectin and its receptors in DR and evaluated the effects of fenofibrate on their expression. The mRNA and protein levels of adiponectin and its receptors were elevated in retinas of streptozotocin-induced diabetic rats and were suppressed following fenofibrate treatment. Immunofluorescence staining demonstrated that adiponectin and adipoR1 were expressed in cells located within blood vessels, the retinal ganglion, and the inner nuclear layer. AdipoR1 was strongly expressed whereas adipoR2 was only weekly expressed in vascular endothelial cells. The in vitro experiments showed that adiponectin expression was induced by high glucose concentrations in RGC-5 and RAW264.7 cells and was suppressed following fenofibrate treatment. AdipoR1 and adipoR2 levels in RGC-5 cells were elevated in high glucose concentrations and suppressed by fenofibrate. Our results demonstrated that adiponectin may be a proinflammatory mediator in diabetic retinas and fenofibrate appears to modulate the expression of adiponectin and its receptors in diabetic retinas, effectively reducing DR progression.

Exercise induced adipokine changes and the metabolic syndrome

The lack of adequate physical activity and obesity created a worldwide pandemic. Obesity is characterized by the deposition of adipose tissue in various parts of the body; it is now evident that adipose tissue also acts as an endocrine organ capable of secreting many cytokines that are though to be involved in the pathophysiology of obesity, insulin resistance, and metabolic syndrome. Adipokines, or adipose tissue-derived proteins, play a pivotal role in this scenario. Increased secretion of proinflammatory adipokines leads to a chronic inflammatory state that is accompanied by insulin resistance and glucose intolerance. Lifestyle change in terms of increased physical activity and exercise is the best nonpharmacological treatment for obesity since these can reduce insulin resistance, counteract the inflammatory state, and improve the lipid profile. There is growing evidence that exercise exerts its beneficial effects partly through alterations in the adipokine profile; that is, exercise increases secretion of anti-inflammatory adipokines and reduces proinflammatory cytokines. In this paper we briefly describe the pathophysiologic role of four important adipokines (adiponectin, leptin, TNF-α, and IL-6) in the metabolic syndrome and review some of the clinical trials that monitored these adipokines as a clinical outcome before and after exercise.

The role of adiponectin gene variants in glycemic control in patients with Type 2 diabetes

The aim of this study was to investigate the association between glycemic control in Type 2 diabetes mellitus patients and common genetic variants of ADIPQO gene. A total of 427 Type 2 diabetes patients were recruited in the study and divided into two groups: 172 patients with good glycemic control and 249 with poor glycemic control. Genotyping of C11377G, G276T and T45G ADIPQO SNPs were carried out using restriction fragment length polymorphisms-polymerase chain reaction. The results showed that C11377G ADIPQO SNP is strongly associated with glycemic control in Type 2 diabetes patients. Patients with the GG genotype at adiponectin C11377G had better glycemic control than those with CC or CG genotypes. However, other examined SNPs were not correlated with glycemic control in Type 2 diabetes patients. Other parameters that impacted glycemic control include duration of the disease (p < 0.01), use of insulin therapy (p < 0.01) and presence of neuropathy complications (p < 0.01). However, no contribution was observed for gender, statin use, lipid profile and other oral medications to glycemic control (p > 0.05). Glycemic control among Type 2 diabetes patients might be affected by variants in ADIPQO gene.

Pivotal role of IL-6 in the hyperinflammatory responses to subacute ozone in adiponectin-deficient mice

Adiponectin is an adipose-derived hormone with anti-inflammatory activity. Following subacute ozone exposure (0.3 ppm for 24-72 h), neutrophilic inflammation and IL-6 are augmented in adiponectin-deficient (Adipo(-/-)) mice. The IL-17/granulocyte colony-stimulating factor (G-CSF) axis is required for this increased neutrophilia. We hypothesized that elevated IL-6 in Adipo(-/-) mice contributes to their augmented responses to ozone via effects on IL-17A expression. Therefore, we generated mice deficient in both adiponectin and IL-6 (Adipo(-/-)/IL-6(-/-)) and exposed them to ozone or air. In ozone-exposed mice, bronchoalveolar lavage (BAL) neutrophils, IL-6, and G-CSF, and pulmonary Il17a mRNA expression were greater in Adipo(-/-) vs. wild-type mice, but reduced in Adipo(-/-)/IL-6(-/-) vs. Adipo(-/-) mice. IL-17A(+) F4/80(+) cells and IL-17A(+) γδ T cells were also reduced in Adipo(-/-)/IL-6(-/-) vs. Adipo(-/-) mice exposed to ozone. Only BAL neutrophils were reduced in IL-6(-/-) vs. wild-type mice. In wild-type mice, IL-6 was expressed in Gr-1(+)F4/80(-)CD11c(-) cells, whereas in Adipo(-/-) mice F4/80(+)CD11c(+) cells also expressed IL-6, suggesting that IL-6 is regulated by adiponectin in these alveolar macrophages. Transcriptomic analysis identified serum amyloid A3 (Saa3), which promotes IL-17A expression, as the gene most differentially augmented by ozone in Adipo(-/-) vs. wild-type mice. After ozone, Saa3 mRNA expression was markedly greater in Adipo(-/-) vs. wild-type mice but reduced in Adipo(-/-)/IL-6(-/-) vs. Adipo(-/-) mice. In conclusion, our data support a pivotal role of IL-6 in the hyperinflammatory condition observed in Adipo(-/-) mice after ozone exposure and suggest that this role of IL-6 involves its ability to induce Saa3, IL-17A, and G-CSF.

Downregulation of uncoupling protein-1 mRNA expression and hypoadiponectinemia in a mouse model of sleep apnea

PURPOSE

The knowledge on the effect of intermittent hypoxia on adipose tissue-mediated processes is incipient. The aim of the present study was to assess the effect of a sleep apnea model on a limited set of specific molecular, biochemical, histological, and behavioral parameters of adipose tissue function.

METHODS

Mice were exposed to either intermittent hypoxia or sham hypoxia during 8 h a day for 37 days. Uncoupling protein-1 expression in brown adipose tissue was measured by real-time PCR and immunohistochemistry. Digital quantification of adipose cells and immunohistochemistry of uncoupling protein-1 were performed to determine cell dimensions, positive area, and staining intensity. Serum levels of leptin, adiponectin, and cortisol were measured by ELISA.

RESULTS

In comparison with the control group, animals in the hypoxia group had significantly lower chow ingestion, weight gain, and smaller white and brown adipocytes on histological examination. Adiponectin levels were also lower in the hypoxia group. Uncoupling protein-1 mRNA was abolished in the mice exposed to hypoxia; accordingly, fewer cells positive for uncoupling protein-1 and lighter staining intensity were observed in brown adipocytes.

CONCLUSIONS

An experimental model of sleep apnea produced changes in uncoupling protein-1 expression and adiponectin levels. These results confirm previous findings on the response of brown adipose tissue to intermittent hypoxia and indicate a yet-unknown interference of intermittent hypoxia on energy control, which may participate in the propensity to weight gain observed in patients with sleep apnea. Brown adipose tissue activity in this patient population needs to be further investigated.

An intragastric balloon produces large weight losses in the absence of a change in ghrelin or peptide YY

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT?: The development of obesity is a multi-factorial process that results in an alteration in the neuroendocrine hormones that help regulate appetite and body weight. Weight loss has been shown to alter this neuroendocrine balance so as to promote weight regain. An intragastric balloon is an effective method to achieve significant weight loss in obese patients and is well suited for those patients who are looking for an alternative to lifestyle modification alone, and those who are not ready or suitable for surgical intervention. Limited research has shown that the weight loss achieved with an intragastric balloon is mediated by altered secretion of the hormones that regulate appetite and weight. WHAT DOES THIS STUDY ADD?: There are currently limited data on the effects of intragastric balloons on appetite and weight-related hormones. In the current study, we have investigated a broad range of gut hormones and adipokines and their response to weight loss induced by differing methods, and the subsequent effect this may have on weight regain. This is an important research area as novel therapies and long-term strategies are needed to counteract the unfavourable changes to the neuroendocrine control of appetite and satiety associated with diet-induced weight loss. This study aims to determine the effect of weight loss achieved with different methods on fasting levels of appetite hormones. Sixty-six obese adults with metabolic syndrome were randomized to intragastric balloon (IGB) for 6 months, with a 12-month behavioural modification programme (IGB group, 'IGBG') or a 12-month behavioural modification programme alone (control group, 'CG'). Anthropometric assessments and blood samples were taken every 3 months and total ghrelin, peptide YY (PYY), adiponectin and leptin were measured. Significant weight-loss differences favouring the IGBG were evident between groups at all time points. Ghrelin increased when the IGB was in situ (+39.3 pmol L(-1) vs. baseline) and returned to baseline after its removal (-34.7 pmol L(-1) ). Adiponectin and PYY levels remained stable in the IGBG, with transient increases noted in the CG. There were no significant between-group differences for ghrelin, PYY or adiponectin. In the IGBG, despite a decrease in leptin at 6 months (-11.7 ng mL(-1) ), levels increased to baseline after IGB removal (-3.7 ng mL(-1) ). In summary, weight loss associated with the IGB did not alter fasting levels of PYY or adiponectin. There was a return of ghrelin and leptin levels to baseline values after IGB removal. No compensatory rise in ghrelin was evident in either group 12 months after initial weight reduction, suggesting that such treatment strategies may lead to better long-term sustainable weight loss.

Association between adiponectin concentrations and cardiovascular disease in diabetic patients: a systematic review and meta-analysis

Background

This systematic review and meta-analysis of prospective studies evaluates the association between adiponectin concentrations and risk of cardiovascular disease (CVD) in individuals with diabetes mellitus (DM).

Methods

PubMed and Embase were searched for prospective studies on the association of adiponectin concentrations and risk of CVD up to June 2013. Random-effect model was selected to pool the relative risk (RR) and 95% CI.

Results

Five prospective cohort studies and one nested case-control studies met the included criterion. The estimated summary RR and 95% CI of five prospective cohort studies for type 2 diabetes comparing top vs low tertile of adiponectin concentrations was 0.99 (95% CI: 0.67–1.45), with significant heterogeneity between studies (p = 0.037, I² = 60.9%). This heterogeneity was explained by one study conducted in Korean.

Conclusions

This study represents the first meta-analysis between adiponectin levels and CVD in diabetic patients and indicated no association was found. This result should be verified further by large sample size, long duration of follow-up, and well-designed prospective clinical trials.

Serum levels of gamma-glutamyl transferase are associated with cardiovascular disease in obstructive sleep apnea syndrome

BACKGROUND AND OBJECTIVES

Obstructive sleep apnea syndrome (OSAS) significantly increases the risk of cardiovascular disease (CVD). Gamma-glutamyl transferase (GGT) is a new marker for predicting CVD. The aim of this study was to evaluate the relationship of serum GGT levels with cardiovascular event, severity of OSAS, and polysomnographic parameters in patients with OSAS.

DESIGN AND SETTINGS

This was a retrospective, cross-sectional study conducted between January 2011 and March 2013 (Gaziosmanpasa University, Faculty of Medicine, Tokat, Turkey).

METHODS

We performed a retrospective study. Patients were divided according to their apnea-hypopnea index (AHI) scores into OSAS negative (AHI < 5, Group 1), mild OSAS (AHI: 5-15, Group 2), moderate OSAS (AHI=15.30, Group 3), and severe OSAS (AHI > 30, Group 4) groups. The presence of heart failure, coronary artery disease, or arrhythmia was defined as CVD.

RESULTS

A total of 320 patients, with a mean age of 50.2 (10.8) years, were included in this study. There were 47, 68, 58, and 147 patients in Groups 1, 2, 3, and 4, respectively. Serum GGT levels were significantly different between groups (Group 1: 25.24 [14.95]; Group 2: 28.03 [11.92]; Group 3: 32.82 [18.18], and Group 4: 40.41 [31.90] mg/dL , P < .001). Besides, serum GGT levels were significantly correlated with AHI, oxygen desaturation index, and average and minimum O2 saturation values (P < .05). Serum GGT levels were significantly higher in patients with CVD compared with those without (P < .05). Multiple regression analysis demonstrated that independent predictors of CVD were serum GGT and low-density lipoprotein-cholesterol levels, age, and body mass index in patients with OSAS.

CONCLUSION

GGT level is an important predictor for CVD in patients with OSAS. The effectiveness of continuous positive airway pressure therapy on CVD and GGT levels should be investigated.