Circulating adiponectin levels are lower in Latino versus non-Latino white patients at risk for cardiovascular disease, independent of adiposity measures

Total adiponectin in indigenous Melanesians on Kitava

OBJECTIVES

Experimental and small human studies have indicated that high total adiponectin levels have beneficial cardiometabolic effects. In contrast, however, high total adiponectin levels are also associated with higher all-cause and cardiovascular mortality in thoroughly adjusted epidemiological studies. To gain further insight into these seemingly contradictory results, we report results on total adiponectin from the indigenous Melanesian population of Kitava, Trobriand Islands, Papua New Guinea, where an apparent absence of cardiometabolic disease has been previously reported.

METHODS

Fasting levels of serum total adiponectin were measured cross-sectionally in ≥40-year-old Kitavans (n = 102) and Swedish controls matched for age and sex (n = 108). Multivariable linear regression was used for the analysis of associations with total adiponectin when controlled for group, sex, smoking, hypertension and/or type 2 diabetes, age, and body mass index.

RESULTS

Total adiponectin was lower for Kitavans compared to Swedish controls (Median [Mdn] 4.6 μg/mL, range 1.0-206 μg/mL and Mdn 9.7 μg/mL, range 3.1-104 μg/mL, respectively, r = .64, p < .001). Lower total adiponectin was associated with Kitavan group, male sex (only in Swedish controls), smoking (only in Kitavans and Swedish controls combined), younger age (not in Swedish controls), higher BMI, lower total, low-density lipoprotein, high-density lipoprotein (HDL) (only in Kitavans and Swedish controls combined), and non-HDL cholesterol, and higher anti-PC IgG (only in Kitavans and Swedish controls combined).

CONCLUSION

Total adiponectin in Kitavans was significantly lower than in Swedish controls.

Reevaluating Adiponectin's impact on obesity hypertension: a Chinese case-control study

BACKGROUND

Obesity and hypertension are major risk factors for cardiovascular diseases that affect millions of people worldwide. Both conditions are associated with chronic low-grade inflammation, which is mediated by adipokines such as adiponectin. Adiponectin is the most abundant adipokine that has a beneficial impact on metabolic and vascular biology, while high serum concentrations are associated with some syndromes. This "adiponectin paradox" still needs to be clarified in obesity-associated hypertension. The aim of this study was to investigate how adiponectin affects blood pressure, inflammation, and metabolic function in obesity hypertension using a Chinese adult case-control study.

METHODS

A case-control study that had finished recruiting 153 subjects divided as four characteristic groups. Adiponectin serum levels were tested by ELISA in these subjects among these four characteristic Chinese adult physical examination groups. Waist circumference (WC), body mass index (BMI), systolic blood pressure (SB), diastolic blood pressure (DB), and other clinical laboratory data were collected. Analyzation of correlations between the research index and differences between groups was done by SPSS.

RESULTS

Serum adiponectin levels in the| normal healthy group (NH group) were significantly higher than those in the newly diagnosed untreated just-obesity group (JO group), and negatively correlated with the visceral adiposity index. With multiple linear egression analysis, it was found that, for serum adiponectin, gender, serum albumin (ALB), alanine aminotransferase (ALT) and high-density lipoprotein cholesterol (HDLC) were the significant independent correlates, and for SB, age and HDLC were the significant independent correlates, and for DB, alkaline phosphatase (ALP) was the significant independent correlate. The other variables did not reach significance in the model.

CONCLUSIONS

Our study reveals that adiponectin's role in obesity-hypertension is multifaceted and is influenced by the systemic metabolic homeostasis signaling axis. In obesity-related hypertension, compensatory effects, adiponectin resistance, and reduced adiponectin clearance from impaired kidneys and liver all contribute to the "adiponectin paradox".

The Relationship of adiponectin level and ADIPOQ gene variants with BMI among young adult women

The current study examined the effect of single nucleotide (SNPs) polymorphisms in the ADIPOQ gene (I146T and G276T) on body mass index (BMI) of young adult women. The women were divided into underweight, normal, overweight and obese according to BMI. The circulating levels of adiponectin were measured using commercially available ELISA kits. Genetic polymorphisms were genotyped using the PCR-RFLP method. G276T and I164T SNPs are common in the examined population as the frequency of G allele of 276 SNP was 54.8% and for the T allele of 164 SNP it was 41.7%. Circulating adiponectin levels were related to BMI and were lowest in the obese versus overweight, normal weight and underweight groups (p<0.01). However, ADIPOQ gene SNPs (I146T and G276T) showed no association with BMI groups. In conclusion, the results may suggest that adiponectin level, but not ADIPOQ gene SNPs, is a good indicator to BMI in young adult women.

Adiponectin and Its Isoforms in Pathophysiology

Adiponectin circulates in blood in multiple isoforms. High molecular weight (HMW) adiponectin is thought to be most biologically active and promotes glucose uptake, insulin sensitivity, and fatty acid oxidation. In obesity, adiponectin isoform formation is disrupted, leading to an inverse association between metabolic disease and HMW and total adiponectin. Adiponectin isoforms also function as acute-phase reactants influencing inflammation in acute and chronic disease. Interestingly, adiponectin and mortality have a U-shaped association. Unfortunately, data concerning adiponectin and its pathophysiologic function conflict. This is predominantly due to difficulties in adequate measurement of adiponectin isoforms and lack of a gold standard. In this review we provide a general overview of the formation and function of adiponectin and its isoforms under physiologic conditions. We highlight the ways adiponectin isoform formation is disrupted in obesity and its ensuing pathologic conditions. Furthermore, we will elaborate on the role of adiponectin isoforms as inflammatory proteins with respect to cardiac and kidney disease and discuss the association of adiponectin with mortality. Finally, we will provide a historical perspective on the measurement of adiponectin isoforms, current limitations, and future challenges.

Ethnic and Sex Differences in Adiponectin: From Childhood to Adulthood

CONTEXT

Insulin resistance (IR) and type 2 diabetes are increasing, particularly in Hispanic (H) vs non-Hispanic White (NHW) populations. Adiponectin has a known role in IR, and therefore, understanding ethnic and sex-specific behavior of adiponectin across the lifespan is of clinical significance.

OBJECTIVE

To compare ethnic and sex differences in adiponectin, independent of body mass index, across the lifespan and relationship to IR.

DESIGN

Cross-sectional.

SETTING

Primary care, referral center.

PATIENTS

A total of 187 NHW and 117 H participants (8-57 y) without diabetes. Life stage: pre-/early puberty (Tanner 1/2), midpubertal (Tanner 3/4), late pubertal (Tanner 5, <21 years), and adult (Tanner 5, ≥21).

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

Fasting adiponectin, insulin, glucose, and revised homeostatic model assessment of insulin resistance.

RESULTS

Adiponectin was significantly inversely correlated with revised homeostatic model assessment of insulin resistance. Regarding puberty, adiponectin trended downward in late puberty, but only males were significantly lower in adulthood. By sex, adiponectin was lower in adult males vs females of both ethnicities. Regarding ethnicity, H adults of both sexes had lower adiponectin than NHW adults. Of note, in NHW females, adiponectin trended highest in adulthood, whereas in H females, adiponectin fell in late puberty and remained lower in adulthood.

CONCLUSIONS

Adiponectin inversely correlated with IR, trended down in late puberty, and was lowest in adult males. H adults of both sexes had lower adiponectin than NHW adults, and H females followed a more "male pattern," lacking the rebound in adiponectin seen in NHW females after puberty. These data suggest that adiponectin, independent of body mass index, may relate to the greater cardiometabolic risk seen in H populations and in particular H females.

The Role of Adiponectin in Cardiometabolic Diseases: Effects of Nutritional Interventions

Adiponectin is an adipocyte-derived hormone abundantly present in plasma that exerts its effects through the activation of 3 receptors. Its concentrations are negatively regulated by the accumulation of visceral fat, and clinical studies implicate hypoadiponectinemia in the pathogenesis of diabetes mellitus type 2, coronary artery disease, hypertension, and left ventricular hypertrophy. In contrast, high concentrations of adiponectin are associated with a decreased risk of coronary artery disease, with an improvement in the differentiation of preadipocytes into adipocytes, and with increased endothelial nitric oxide production. Therefore, adiponectin appears to be an important molecule involved in limiting the pathogenesis of obesity-linked disorders, and it may have potential benefits in the treatment and prevention of cardiovascular disease. Caloric restriction, moderate alcohol consumption, and consuming a Mediterranean diet increase adiponectin concentrations, and current evidence suggests a positive, dose-dependent relation between ω-3 (n-3) fatty acid intake and circulating concentrations of adiponectin. Recently, it was reported that the administration of aged garlic extract and a single food intervention with pistachios can increase adiponectin concentrations in individuals with metabolic syndrome. Moreover, the Mediterranean diet is associated with higher adiponectin concentrations. Additional studies are needed to evaluate the potential benefits of increasing adiponectin by nutritional interventions in the treatment and prevention of cardiometabolic diseases.

Associations of Adiponectin with Adiposity, Insulin Sensitivity, and Diet in Young, Healthy, Mexican Americans and Non-Latino White Adults

Low circulating adiponectin levels may contribute to higher diabetes risk among Mexican Americans (MA) compared to non-Latino whites (NLW). Our objective was to determine if among young healthy adult MAs have lower adiponectin than NLWs, independent of differences in adiposity. In addition, we explored associations between adiponectin and diet. This was an observational, cross-sectional study of healthy MA and NLW adults living in Colorado (U.S.A.). We measured plasma total adiponectin, adiposity (BMI, and visceral adipose tissue), insulin sensitivity (IVGTT), and self-reported dietary intake in 43 MA and NLW adults. Mean adiponectin levels were 40% lower among MA than NLW (5.8 ± 3.3 vs. 10.7 ± 4.2 µg/mL, p = 0.0003), and this difference persisted after controlling for age, sex, BMI, and visceral adiposity. Lower adiponectin in MA was associated with lower insulin sensitivity (R² = 0.42, p < 0.01). Lower adiponectin was also associated with higher dietary glycemic index, lower intake of vegetables, higher intake of trans fat, and higher intake of grains. Our findings confirm that ethnic differences in adiponectin reflect differences in insulin sensitivity, but suggest that these are not due to differences in adiposity. Observed associations between adiponectin and diet support the need for future studies exploring the regulation of adiponectin by diet and other environmental factors.

Autocrine/paracrine function of globular adiponectin: inhibition of lipid metabolism and inflammatory response in 3T3-L1 adipocytes

Adiponectin is an adipose-derived hormone, with beneficial effects on insulin sensitivity and inflammation. The aim of this study was to clarify the autocrine/paracrine effects of globular adiponectin (gAd) administrated during differentiation on the function of the mature adipocytes. Experiments were performed on 3T3-L1 preadipocytes treated with gAd (10 nM), starting at an early stage of differentiation. gAd treatment during differentiation was without effect on mRNA expression of adiponectin and AdipoR2, but increased AdipoR1 expression. PPARgamma, perillipin and FABP4 mRNA expressions were lower in gAd-treated adipocytes, accompanied by a reduction in lipid accumulation. While mRNA expression of HSL was not affected by gAd compared to untreated adipocytes, both ATGL and FAS were reduced, indicating that gAd regulates both lipolysis and lipogenesis. PPARα, ACOX2 and UCPs mRNA expressions were not affected by gAd, indicating that the reduction in lipid content is not attributed to an increase in fatty-acid oxidation. In accord with the lower PPARγ expression, there was reduced Glut4 mRNA expression; however, insulin-induced PKB phosphorylation was enhanced by gAd, and glucose uptake was not altered. To investigate the effect of gAd on LPS-induced inflammatory response, cells were treated with gAd either during differentiation or 24 h before induction of inflammation in differentiated adipocytes. LPS-induced inflammatory response, as indicated by increase in IL6 and MCP-1 mRNA expression. gAd given through differentiation was much more effective in abrogating LPS-dependent cytokines production than gAd given to the mature adipocyte. In conclusion, elevated gAd at differentiation of 3T3-L1 cells leads to reduced lipid content, reduced lipid metabolism and high resistance to inflammation.

Comprehensive analysis of circulating adipokines and hsCRP association with cardiovascular disease risk factors and metabolic syndrome in Arabs

Background

Cardiovascular diseases (CVD) are a leading cause of death worldwide including the Middle East. This is caused in part by the dysregulation of adipose tissue leading to increased production of pro-inflammatory adipokines and reduction in cardio-protective adipokines such as adiponectin. Ethnicity has been recognized as a major factor in the association between CVD risk factors and the different circulating adipokines. In this study, for the first time, the relationship between traditional cardiovascular risk factors, Metabolic Syndrome (MetS) and circulating level of adipokines in Arab ethnicity was investigated.

Methods

We conducted a population-based cross-sectional survey on 379 adult Arab participants living in Kuwait. Traditional cardiovascular risk factors such as blood pressure (BP), low density lipoprotein (LDL) and triglyceride (TG) were measured. Plasma levels of circulating Leptin, Plasminogen Activator Inhibitor (PAI-1) visfatin, adiponectin, resistin and adipsin were assessed using the multiplexing immunobead-based assay.

Results

Circulating levels of High sensitivity C-Reactive Protein (hsCRP), Leptin, PAI-1 and adiponectin were significantly higher in Arab women than men (p < 0.0001). In multi-variate analysis, the homeostasis model assessment-insulin resistance (HOMA-IR) and body mass index (BMI) showed strong association with most of the biomarkers (p < 0.05). HsCRP showed significant association with all risk factors (p < 0.05). Leptin, PAI-1 and adipsin showed significant positive correlation with BMI, unlike adiponectin which showed inverse correlation (p < 0.05). Subjects in the highest tertile of leptin, PAI-1 and hsCRP had higher odds of having Metabolic Syndrome (MetS) (odd ratio [OR] = 3.02, 95% confidence interval [CI] = 1.47 – 6.19) and (OR = 2.52, 95% CI = 1.45 – 4.35), (OR = 4.26, 95% CI = 2.39 – 7.59) respectively. On the other hand subjects with highest tertile of adiponectin had lower odds of having MetS (OR = 0.22, 95% CI = 0.12 – 0.40). Leptin, PAI-1 and hsCRP showed significant positive association with increased MetS components (P-trend <0.05), while adiponectin was negatively associated with increased MetS components (P-trend <0.0001).

Conclusion

Our results show positive association between hsCRP, leptin, PAI-1 with increased MetS components and increase the odds of having MetS. Adiponectin on the other hand showed inverse correlation with MetS components and associated with reduction in MetS. Overall, our data highlights the significant clinical value these markers have in MetS especially hsCRP which can be used as good marker of low grade inflammation in Arabs.

Links between obesity, diabetes and ethnic disparities in breast cancer among Hispanic populations

Breast cancer is the most prevalent malignancy in women worldwide and is a growing concern due to rising incidence and ongoing ethnic disparities in both incidence and mortality. A number of factors likely contribute to these trends including rising rates of obesity and diabetes across the globe and differences in genetic predisposition. Here, we emphasize Hispanic populations and summarize what is currently known about obesity, diabetes and individual genetic predisposition as they relate to ethnic disparities in breast cancer incidence and mortality. In addition, we discuss potential contributions to breast cancer aetiology from molecular mechanisms associated with obesity and diabetes including dyslipidemia, hyperglycaemia, hyperinsulinaemia, endocrine dysfunction and inflammation. We propose that unique differences in diet and lifestyle coupled with individual genetic predisposition and endocrine/immune dysfunction explain most of the ethnic disparities seen in breast cancer incidence and mortality.

Low serum adiponectin concentrations are associated with insulin sensitivity independent of obesity in Sudanese subjects with type 2 diabetes mellitus

AIMS

Prevalence of Type 2 diabetes mellitus among Sudanese population was found to be 3.4% and associated with high rates of complications and obesity. Different adipocytokines are secreted from adipose tissues, among them adiponectin, which was shown to have insulins ensitizing properties and anti-inflammatory, anti-atherogenic effect. The aim of this study was to characterize type 2 diabetes in Sudanese diabetic subjects and controls in respect to hormones influencing or influenced by glucose metabolism.

METHODS

104 type 2 diabetic patients (45 men and 59 women), and 75 matched control subjects (34 men and 41 women) were studied. Fasting serum samples were used to measure adiponectin, leptin, insulin, proinsulin, ghrelin and glucose. Body mass index, insulin/proinsulin ratio and (HOMA) insulin resistance and beta cell function were also calculated.

RESULTS

Adiponectin serum concentrations were significantly lower in subjects with type 2 diabetes compared with controls subjects (P = 0.002), comparison between males and females did not reach significant levels in both diabetic (P = 0.06) or controls (P = 0.16) groups. In the diabetic group adiponectin correlated positively with serum glucose, negatively with serum proinsulin and HOMA beta cell function (P = 0.03) respectively and serum ghrelin (P = 0.003), but not with BMI, HOMA insulin resistance, insulin or leptin. In controls serum adiponectin correlated negatively with BMI (P = 0.002) but not with other variables.

CONCLUSIONS

The findings of this study suggest that, adiponectin concentrations independent on BMI as a measure of adiposity, were mostly linked to insulin sensitivity and not to insulin resistance in Sudanese type 2 diabetic subjects, where race specific regulation mechanisms or different type 2 diabetes phenotype suggested being a major contributory factor in clarification the findings of this study.