Association of genetic variation of the adiponectin gene with body fat distribution and carotid atherosclerosis in Japanese obese subjects

Imaging of atherosclerotic plaques in obesity: excessive fat accumulation, plaque progression and vulnerability

Obesity is becoming a major health issue in the world due to sedentary lifestyles and increasing intake of Western diets. Obesity is associated with metabolic abnormalities and atherosclerotic cardiovascular diseases. Adipose tissue has been increasingly considered to play a critical role in inducing metabolic disturbances and promoting atherogenesis. Arterial wall imaging permits direct visualization of atheroma burden in various vascular beds. In addition, recent advances in imaging technology help characterize components, microstructures and functional features of atherosclerotic plaques. These imaging modalities have contributed to elucidating factors associated with atherosclerosis in obese patients. Also, it provides opportunities to evaluate the effect of novel therapies on plaques in the setting of obesity. The findings of recent imaging studies and the clinical implications will be reviewed.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Association of ADIPOQ +45T>G polymorphism with body fat mass and blood levels of soluble adiponectin and inflammation markers in a Mexican-Mestizo population

PURPOSE

Obesity is a disease with genetic susceptibility characterized by an increase in storage and irregular distribution of body fat. In obese patients, the decrease in the Adiponectin gene (ADIPOQ) expression has been associated with a systemic low-grade inflammatory state. Our aim was to investigate the relationship between ADIPOQ +45T>G gene simple nucleotide polymorphism (SNP rs2241766) with serum adiponectin (sAdiponectin), distribution of body fat storage, and inflammation markers.

SUBJECTS AND METHODS

In this cross-sectional study, 242 individuals from Western Mexico characterized as Mexican-Mestizo and classified by body mass index (BMI), were included. Anthropometrics, body composition, body fat distribution, and inflammation markers were measured by routine methods. Genotypes were characterized using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique and sAdiponectin by the ELISA method. A P-value <0.05 was considered the statistically significant threshold.

RESULTS

sAdiponectin is associated with BMI (P < 0.001) and the genotypes (P < 0.001 to 0.0046) GG (8169 ± 1162 ng/mL), TG (5189 ± 501 ng/mL), and TT (3741 ± 323 ng/mL), but the SNP ADIPOQ +45T>G is not associated with BMI. However, the detailed analysis showed association of this SNP with a pattern of fat distribution and correlations (P < 0.05) with inflammation markers and distribution of body fat storage (Pearson's r = -0.169 to -0.465) were found.

CONCLUSION

In this study, we have suggested that the ADIPOQ +45G allele could be associated with distribution of body fat storage in obesity. On the other hand, as no association was observed between ADIPOQ +45T>G gene polymorphism and obesity, it cannot be concluded that the ADIPOQ +45G allele is responsible for the increase of adiponectin levels.

Genetic variations in APPL2 are associated with overweight and obesity in a Chinese population with normal glucose tolerance

Background

APPL1 and APPL2 are two adaptor proteins, which can mediate adiponectin signaling via binding to N terminus of adiponectin receptors in muscle cells. Genes encoding adiponectin and adiponectin receptors contribute to insulin resistance and the risk of obesity, and genetic variants of APPL1 are associated with body fat distribution. However, the association between genetic variations of APPL2 and metabolic traits remains unknown. In the current study, we aimed to test the impacts of APPL2 genetic variants on obesity in a Chinese population with normal glucose tolerance.

Methods

We genotyped six single nucleotide polymorphisms (SNPs) in APPL2 in 1,808 non-diabetic subjects. Overweight and obesity were defined by body mass index (BMI). Obesity-related anthropometric parameters were measured, including height, weight, waist circumference, hip circumference. BMI and waist-hip ratio (WHR) were calculated.

Results

We found significant evidence of association with overweight/obesity for rs2272495 and rs1107756. rs2272495 C allele and rs1107756 T allele both conferred a higher risk of being overweight and obese (OR 1.218, 95% CI 1.047-1.416, p = 0.011 for rs2272495; OR 1.166, 95% CI 1.014-1.341, p = 0.031 for rs1107756). After adjusting multiple comparisons, only the effect of rs2272495 on overweight/obesity remained to be significant (empirical p = 0.043). Moreover, we investigated the effects of these SNPs on obesity-related quantitative traits in all participants. rs2272495 was associated with BMI (p = 0.015), waist circumference (p = 0.006), hip circumference (p = 0.025) as well as WHR (p = 0.047) under a recessive model. Similar associations were found for rs1107756 except for WHR.

Conclusion

This study suggests that genetic variations in APPL2 are associated with overweight and obesity in Chinese population with normal glucose tolerance.

Genetic effects of adiponectin on blood lipids and blood pressure

OBJECTIVE

Results from the published studies on the association of adiponectin gene (ADIPOQ) polymorphisms with blood lipids and blood pressure are conflicting. We investigated the association of three ADIPOQ polymorphisms, +45 T > G (rs2241766), +276 G > T (rs1501299) and -11377 C > G (rs266729), with these traits in this meta-analysis.

RESEARCH DESIGN AND METHODS

We included 35 studies in this meta-analysis. Dominant models were used for this meta-analysis.

RESULTS

We did not detect a significant association of the -11377 C > G polymorphism with blood lipids or blood pressure (P > 0·05). The association of the +45 T > G polymorphism with blood lipids and blood pressure was, similarly, not significant (P > 0·05). The meta-analysis suggested a significant overall association of the +276 G > T polymorphism with lower levels of total cholesterol: weighted mean difference (WMD) = -0·10, 95% confidence interval (CI, -0·17, -0·03), P = 0·005, P(heterogeneity)  = 0·04. This association was marginally significant in East Asians and East Asians with type 2 diabetes: WMD = -0·10, 95% CI (-0·20, 0·00), P = 0·05, P(heterogeneity)  = 0·002, and WMD = -0·09, 95% CI (-0·18, -0·00), P = 0·05, P(heterogeneity)  = 0·80, respectively. After exclusion of a study that was the source of heterogeneity, the association was significant in overall populations and marginally significant in East Asians: WMD= -0·06, 95% CI (-0·11, -0·01), P = 0·01, P(heterogeneity)  = 0·98, and WMD = -0·06, 95% CI (-0·12, 0·00), P = 0·07, P(heterogeneity)  = 0·83, respectively. However, none of these associations were significant after Bonferroni correction (significant threshold: P < 0·003).

CONCLUSIONS

Our meta-analysis does not suggest any association of the three ADIPOQ polymorphisms with blood lipids and blood pressure.

Relations between serum reactive oxygen metabolites (ROMs) and various inflammatory and metabolic parameters in a Japanese population

AIM

Both oxidative stress and inflammation are known to play roles in the pathogenesis of cardiovascular disease. We investigated the relations between reactive oxygen metabolites (ROMs) and various inflammatory and metabolic parameters in a Japanese population.

METHODS

We analyzed 48 male and 69 female subjects, aged 25 to 65 years, who underwent an annual health checkup in our university. Serum ROM level was assayed using a free radical elective evaluator. We also measured serum concentrations of high-sensitivity C-reactive protein (hsCRP), insulin, and high molecular weight (HMW) adiponectin.

RESULTS

Although the serum ROM level in females (347+/-83 Carr U) was slightly higher than in males (333+/-53 Carr U), this was not statistically significant. In the 48 male subjects, the ROM level negatively correlated with age (r=-0.344, p=0.0161), and positively correlated with the hsCRP level (r=0.306, p=0.0338). In the 69 female subjects, the ROM level negatively correlated with serum creatinine (r=-0.293, p=0.0141), and positively correlated with insulin (r=0.278, p=0.0202), the insulin resistance index (r=0.286, p=0.0170) and hsCRP levels (r=0.487, p<0.0001). Stepwise multiple regression analysis revealed that serum hsCRP, creatinine, and age were independently correlated with the serum ROMs level (R2=0.365; F value highest for hsCRP). When the study subjects were divided into tertiles according to the ROM level, serum hsCRP was significantly different among the three groups: its level was highest in the highest tertile of ROMs (p<0.001).

CONCLUSION

These results suggest that the serum ROM level is closely associated with serum hsCRP in Japanese adult subjects.

Antiobesity and antidiabetic effects of biotransformed blueberry juice in KKA(y) mice

AIM

Biotransformation of blueberry juice by the Serratia vaccinii bacterium gave rise to adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and glucose uptake in muscle cells and adipocytes, but inhibited adipogenesis. This study investigated the antiobesity and antidiabetic potential of biotransformed blueberry juice (BJ) in KKA(y) mice, rodent model of leptin resistance.

METHODS

BJ was incorporated in drinking water of KKA(y) mice. Parameters of body weight, food intake, plasma glucose, insulin, leptin, and adiponectin were measured. Before and after therapy, animals were subjected to an oral glucose tolerance test. At the end of treatment, liver, muscle, kidney, epididymal fat pad, abdominal fat pad, and dorsal fat pad were collected and weighed.

RESULTS

Incorporating BJ in drinking water protected young KKA(y) mice from hyperphagia and significantly reduced their weight gain. Moreover, BJ protected young KKA(y) mice against the development of glucose intolerance and diabetes mellitus. Chronic BJ administration in obese and diabetic KKA(y) mice reduced food intake and body weight. This effect could not fully explain the associated antidiabetic effect because BJ-treated mice still showed lower blood glucose level when compared with pair-fed controls. The adipokines pathway also seems to be involved because BJ significantly increased adiponectin levels in obese mice.

CONCLUSIONS

This study shows that BJ decreases hyperglycemia in diabetic mice, at least in part by reversing adiponectin levels. BJ also protects young pre-diabetic mice from developing obesity and diabetes. Thus, BJ may represent a novel complementary therapy and a source of novel therapeutic agents against diabetes mellitus.

Adiponectin and adiponectin receptors in human pheochromocytoma

AIM

Recent studies have demonstrated that serum adiponectin and its receptors in adipose and muscle tissues are suppressed in diabetic or obese individuals. Patients with pheochromocytoma are frequently diabetic.

METHODS

Using real-time PCR, we examined mRNA expressions of adiponectin (Adp) and adiponectin receptor 1 (AdpR1) and AdpR2 in pheochromocytoma tissues from 49 patients. We also measured levels of serum total and high molecular weight (HMW) adiponectin levels in 10 pheochromocytomas and 33 normal volunteers.

RESULTS

In pheochromocytoma tissue, AdpR1 mRNA expression was higher in adrenaline (A)-type tumors than in noradrenaline (NA)-type tumors. AdpR1 expression was significantly higher in A-type non-diabetics than in NA-type non-diabetics (p<0.05). AdpR1 mRNA expression was significantly associated with the tumor tissue adrenaline content (p<0.005) in linear regression analysis, which suggest that adrenaline positively regulates AdpR1 mRNA expression.Serum total and HMW Adp levels in patients with NA-type pheochromocytomas were approximately 3 times higher than those of healthy volunteers. After adrenalectomy, levels of adiponectin normalized.

CONCLUSION

Our results indicate that serum total and HMW Adp, and AdpR1 gene expressions in pheochromocytoma tissue, are associated with the level of catecholamine produced in the tumor. It is tempting to speculate that catecholamine induces adiponectin production and signaling.

Correlation between adiponectin polymorphisms and non-alcoholic fatty liver disease with or without metabolic syndrome in Chinese population

BACKGROUND

To investigate the effect of single nucleotide polymorphisms (SNP) 45 and 276 of the adiponectin gene on non-alcoholic fatty liver disease (NAFLD) with or without metabolic syndrome.

METHODS

A total of 165 NAFLD, 83 NAFLD with metabolic syndrome and 160 healthy controls from Chinese population were genotyped for the adiponectin gene (+45T>G and +276G>T) by PCR-restriction fragment length polymorphism methods. Plasma adiponectin and insulin levels were determined by enzyme-linked immunosorbent assay and radioimmunoassay, respectively. Insulin resistance (IR) was evaluated by using homeostasis model assessment of IR (HOMA-IR).

RESULTS

NAFLD with metabolic syndrome had further extent of IR and hypoadiponectinemia. No association of SNP45 or SNP276 was found in NAFLD or NAFLD with metabolic syndrome. Subjects carrying the G allele of SNP45 showed higher levels of triglyceride (TG), fasting blood sugar (FBS), HOMA, body mass index (BMI), and alanine transaminase (ALT), as well as lower plasma adiponectin levels. In the normal-weight group of SNP276, subjects carrying the G allele showed higher HOMA and subjects carrying the T allele showed lower BMI.

CONCLUSIONS

Our study observed further hypoadiponectinemia and IR in NAFLD with metabolic syndrome. The T45G and G276T of the adiponectin gene may not be the important determinants of NAFLD in Chinese people, but some of them still influence serum ALT, BMI, IR, lipid, glucose metabolism and plasma adiponectin concentration.

The association of adiponectin allele 45T/G and -11377C/G polymorphisms with Type 2 diabetes and rosiglitazone response in Chinese patients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Rosiglitazone is able to increase serum adiponectin levels significantly in Type 2 diabetic patients. :The role of genetic factors that determine the marked interindividual variability in glucose-lowering efficacy of rosiglitazone in Chinese patients is not known. The current study was designed to evaluate the impact of the adiponectin common allele 45T/G and -11377C/G polymorphisms on the response to rosiglitazone monotherapy in Chinese patients with Type 2 diabetes (T2D).

WHAT THIS STUDY ADDS

The genetic polymorphisms of adiponectin alleles 45T/G and -11377C/G as well as their common diplotypes are significantly associated with an attenuated fasting plasma glucose, postprandial plasma glucose and homeostasis model assessment for insulin resistance as well as an enhanced adiponectin concentration in Chinese patients with T2D after rosiglitazone treatment. AIMS The aim of the present study was to evaluate the impact of adiponectin allele T45G and C-11377G genetic polymorphisms on efficacy of rosiglitazone in Chinese patients with type 2 diabetes (T2D).

METHODS

Patients with T2D (n = 255) and 120 healthy volunteers were enrolled to identify 45T/G and -11377C/G genotypes by polymerase chain reaction-restriction fragment length polymorphism assay. Forty-two T2D patients with different 45T/G or -11377C/G genotypes received orally rosiglitazone as a single-dose therapy (4 mg day-1 p.o.) for 12 weeks. Serum triglyceride, fasting plasma glucose (FPG), postprandial plasma glucose (PPG), glycated hemoglobin, fasting serum insulin, postprandial serum insulin, total cholesterol, homeostasis model assessment for insulin resistance (HOMA-IR), low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol (HDL-c) and adiponectin concentration were determined before and after rosiglitazone treatment.

RESULTS

We showed an attenuated rosiglitazone effect in patients with -11377CG+GG heterozygote genotype on FPG, PPG, HOMA-IR compared with -11377CC homozygote genotype. However, we found an enhanced rosiglitazone effect on serum adiponectin concentration in patients with -11377CC homozygote genotype compared with -11377CG+GG heterozygote genotype (P = 0.000) and in patients with 45TG + GG heterozygote genotype compared with 45TT homozygote genotype (P = 0.018). Finally, our results showed that there was an enhanced effect in patients with -11377/45 CGTT diplotype compared with other discovered diplotypes on FPG (P = 0.001) and PPG (P = 0.003) after rosiglitazone treatment.

CONCLUSIONS

These data suggest that the adiponectin allele 45T/G and -11377C/G polymorphisms are significantly associated with the therapeutic efficacy of multiple-dose rosiglitazone in Chinese patients with T2D.