Association of the leptin to high-molecular-weight adiponectin ratio with metabolic syndrome

Can biomarkers be used to improve diagnosis and prediction of metabolic syndrome in childhood cancer survivors? A systematic review

Childhood cancer survivors (CCS) are at increased risk to develop metabolic syndrome (MetS), diabetes, and cardiovascular disease. Common criteria underestimate adiposity and possibly underdiagnose MetS, particularly after abdominal radiotherapy. A systematic literature review and meta-analysis on the diagnostic and predictive value of nine newer MetS related biomarkers (adiponectin, leptin, uric acid, hsCRP, TNF-alpha, IL-1, IL-6, apolipoprotein B (apoB), and lipoprotein(a) [lp(a)]) in survivors and adult non-cancer survivors was performed by searching PubMed and Embase. Evidence was summarized with GRADE after risk of bias evaluation (QUADAS-2/QUIPS). Eligible studies on promising biomarkers were pooled. We identified 175 general population and five CCS studies. In the general population, valuable predictive biomarkers are uric acid, adiponectin, hsCRP and apoB (high level of evidence), and leptin (moderate level of evidence). Valuable diagnostic biomarkers are hsCRP, adiponectin, uric acid, and leptin (low, low, moderate, and high level of evidence, respectively). Meta-analysis showed OR for hyperuricemia of 2.94 (age-/sex-adjusted), OR per unit uric acid increase of 1.086 (unadjusted), and AUC for hsCRP of 0.71 (unadjusted). Uric acid, adiponectin, hsCRP, leptin, and apoB can be alternative biomarkers in the screening setting for MetS in survivors, to enhance early identification of those at high risk of subsequent complications.

Fetuin-a to adiponectin ratio is a sensitive indicator for evaluating metabolic syndrome in the elderly

Background

Fetuin-A and adiponectin present significant associations, supported by recent evidence, with metabolic syndrome (MS) featuring hyperglycemia, central obesity and insulin resistance as the main components, but their biological functions are opposite. The aim of this study was to verify whether fetuin-A/adiponectin ratio (F/A ratio) is a more sensitive indicator for evaluation of MS than either fetuin-A or adiponectin.

Methods

In this cross-sectional study, 465 elderly subjects were selected from the physical examination database. Serum levels of fetuin-A and adiponectin were measured using an enzyme-linked immunosorbent assay (ELISA) method. Spearman’s rank correlation coefficient, linear regression and logistic regression analysis were adopted to estimate the correlations of fetuin-A, adiponectin and F/A ratio with MS and its components, and receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive values of the aforesaid indices.

Results

Compared with fetuin-A or adiponectin, F/A ratio was significantly associated with all the components of MS, and this correlation was significant even after adjusting potential confounding factors (P < 0.05). Logistic regression analysis indicated that F/A ratio presented a stronger correlation with incident MS (adjusted OR: 1.466; 95% CI: 1.189–1.808) than fetuin-A (adjusted OR: 1.100; 95% CI: 1.020–1.186) and adiponectin (adjusted OR: 0.760; 95% CI: 0.664–0.871) alone. ROC analysis revealed that F/A ratio achieved a larger area under curve (AUC) than fetuin-A and adiponectin, with their AUC values of 0.755, 0.709 and 0.708, respectively.

Conclusion

F/A ratio is a more sensitive index for evaluating MS than either fetuin-A or adiponectin in the elderly.

The clinical potential of circulating microRNAs in obesity

Obesity is a complex condition that is characterized by excessive fat accumulation, which can lead to the development of metabolic disorders, such as type 2 diabetes mellitus, nonalcoholic fatty liver disease and cardiovascular diseases. Evidence is accumulating that circulating microRNAs (miRNAs) act as a new class of endocrine factor. These miRNAs are released by many types of tissue, including adipose tissues. miRNAs might serve as endocrine and paracrine messengers that facilitate communication between donor cells and tissues with receptor cells or target tissues, thereby potentially having important roles in metabolic organ crosstalk. Moreover, many miRNAs are closely associated with the differentiation of adipocytes and are dysregulated in obesity. As such, circulating miRNAs are attractive potential biomarkers and hold promise for the development of miRNA-based therapeutics (such as miRNA mimetics, anti-miRNA oligonucleotides and exosomes loaded with miRNA) for obesity and related disorders. Here we review the latest research progress on the roles of circulating miRNAs in metabolic organ crosstalk. In addition, we discuss the clinical potential of circulating miRNAs as feasible biomarkers for the assessment of future risk of metabolic disorders and as therapeutic targets in obesity and related diseases.

Leptin-adiponectin imbalance as a marker of metabolic syndrome among Chinese children and adolescents: The BCAMS study

Purpose

Leptin and adiponectin have opposite effects on subclinical inflammation and insulin resistance, both involved in the development of metabolic syndrome (MS). We aimed to investigate whether leptin/adiponectin ratio (L/A), as a marker of these two adipokines imbalance, may improve diagnosis of MS in children and adolescents, and determined its cut-off value in the diagnosis of MS.

Methods

A total of 3,428 subjects aged 6–18 years were selected from Beijing Child and Adolescent Metabolic Syndrome study. Adipokine leptin and adiponectin were measured using enzyme-linked immunosorbent assay. Odds ratio of MS per 1 z-score of adipokine was examined using logistic regression. Diagnosis accuracy was assessed using c-statistics (AUC) and net reclassification index.

Results

The levels of leptin and L/A increased with number of positive MS components, while the levels of adiponectin declined in both boys and girls (all P <0.001). AUCs for diagnosis of MS in girls were 0.793, 0.773, and 0.689 using L/A, leptin and adiponectin, respectively; and AUCs in boys were 0.822, 0.798, and 0.697 for L/A, leptin and adiponectin, respectively. Notably, L/A outperformed individual leptin or adiponectin in discriminating a diagnosis of MS (all P < 0.02 in AUC comparisons). In addition, the optimal cut-offs of L/A by ROC curve differed by genders and pubertal stages, which were 1.63, 1.28, 1.95 and 1.53 ng/ug for total, pre-, mid- and postpubertal boys, respectively and 2.19, 0.87,1.48 and 2.27 ng/ug for total, pre-, mid- and postpubertal girls, respectively, yielding high sensitivity and moderate specificity for a screening test.

Conclusions

In this pediatric population, leptin-adiponectin imbalance, as reflected by an increase in L/A level, was found to be a better diagnostic biomarker for MS than leptin or adiponectin alone. Future longitudinal studies are needed to further validate the gender-specific cutoff values.

Effects of cold sensitivity in the extremities on circulating adiponectin levels and metabolic syndrome in women

Background

In adipose tissues, adipokine levels, including adiponectin and leptin, are involved in insulin sensitivity and are reciprocally induced by cold temperature stress. Thermogenic response in the extremities (hands and feet) against cold stress can be negatively related to fat mass accumulation, particularly in the abdomen. However, the relationship between the sensation of cold in the extremities and circulating levels of adipokines is not fully understood. Here, we investigated whether adipokine levels are associated with cold hypersensitivity in the hands and feet (CHHF), independent of body mass, and whether the CHHF is related to metabolic syndrome (MS).

Methods

Associations of the CHHF with serum levels of adipokines and MS risk were evaluated in 1021 Koreans (372 men and 649 women), using a linear regression model while controlling for thermogenic factors and a logistic regression model, respectively.

Results

The adiponectin levels were positively associated with the CHHF, particularly in women, irrespective of thermogenic factors, including body mass index (β = 1.23 μg/mL, 95% confidence interval [1.04–1.45]). Logistic regression analysis for MS risk via the CHHF showed that there was a significant inverse association in women (odds ratio = 0.449, 95% confidence interval [0.273–0.737]).

Conclusions

In summary, our founding indicated that the CHHF could induce increased levels of circulating adiponectin and in turn reduce the MS risk in women. Despite complaints of feeling cold, these women could be at lower risk of cardiovascular disease.

Leptin and adiponectin as predictors of cardiovascular risk after gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) is a significant risk factor for cardiovascular disease (CVD) in later life, but the mechanism remains unclear. Adipokine imbalance in the presence of metabolic dysfunction may be a key event in promoting CVD. The aim of the study was to examine the relationships between GDM, cardiovascular risk, and plasma adiponectin, leptin and the leptin/adiponectin (L/A) ratio in pregnancy and at 5 years after the index pregnancy.

METHODS

This population-based prospective cohort included 300 women who had an oral glucose tolerance test (OGTT) during pregnancy. Five years later, the OGTT was repeated along with dual-energy X-ray absorptiometry, lipid analysis, and pulse wave velocity analysis. Fasting adiponectin and leptin levels were measured four times during pregnancy and at follow-up.

RESULTS

We found the L/A ratio higher in GDM women both during pregnancy and follow-up compared to non-GDM women. A high L/A ratio during pregnancy was associated with CV risk based on lipid ratios at follow-up, especially the TG/HDL-C ratio. Further, interaction analysis indicated that an increase in the L/A ratio of 1 unit was associated with a higher CV risk in GDM compared to normal pregnancy. Finally, low adiponectin levels independently predicted increased lipid ratios at follow-up.

CONCLUSIONS

Taken together, our findings suggest that high L/A ratio in pregnancy and in particularly in those with GDM are associated with an unfavorable CVD risk profile during follow-up. Future studies should investigate if a dysregulated leptin and adiponectin profile during pregnancy is associated with atherosclerotic disease during long-term follow-up.

Adiponectin, Leptin and Objectively Measured Physical Activity in Adults: A Narrative Review

The objective of this study was to compile and analyse existing scientific evidences reporting the effects of objectively measured physical activity on the levels of adiponectin and leptin. Articles related to the effects of objectively measured physical activity on the levels of adiponectin and leptin were searched from the Medline and PubMed databases. The search was limited to 'objectively measured' physical activity, and studies that did not objectively measure the physical activity were excluded. Only English articles were included in the search and review. A total of 18 articles encompassing 2,026 respondents met the inclusion criteria. The eligible articles included all forms of evidence (e.g., cross-sectional and intervention). Seventeen and 11 studies showed the effects of objectively measured physical activity on adiponectin and leptin, respectively. Five and four cross-sectional studies showed the effects of objectively measured physical activity on adiponectin and leptin, respectively. Two out of five studies showed a weak to moderate positive association between adiponectin and objectively measured physical activity, while three out of four studies showed a weak to moderate inverse association between leptin and objectively measured physical activity. For intervention studies, six out of 12 studies involving adiponectin and five out of seven studies involving leptin showed a significant effect between the proteins and objectively measured physical activity. However, a definitive conclusion could not be drawn due to several methodological flaws in the existing articles and the acute lack of additional research in this area. In conclusion, the existing evidences are encouraging but yet not compelling. Hence, further well-designed large trials are needed before the effectiveness of objectively measured physical activity in elevating adiponectin levels and in decreasing leptin levels could be strongly confirmed.

Association of Metabolic Syndrome with the Adiponectin to Homeostasis Model Assessment of Insulin Resistance Ratio

This study aimed at determining whether the adiponectin to HOMA-IR (A/H) ratio is associated with MetS and MetS components and comparing the diagnostic efficacy of adiponectin, HOMA-IR, and the A/H ratio in healthy, middle-aged participants. MetS was assessed in 1628 Kazakh participants (men, 768; women, 860). The associations between adiponectin, HOMA-IR, and the A/H ratio with the components of MetS and MetS were examined using logistic regression analysis and receiver operating characteristic (ROC) curves. Our results show that A/H ratio may be a better diagnostic marker for MetS than either HOMA-IR or adiponectin alone, and it may serve as an important biomarker to determine an increased risk for MetS in healthy middle-aged population.

Differential effects of leptin and adiponectin in endothelial angiogenesis

Obesity is a major health burden with an increased risk of cardiovascular morbidity and mortality. Endothelial dysfunction is pivotal to the development of cardiovascular disease (CVD). In relation to this, adipose tissue secreted factors termed "adipokines" have been reported to modulate endothelial dysfunction. In this review, we focus on two of the most abundant circulating adipokines, that is, leptin and adiponectin, in the development of endothelial dysfunction. Leptin has been documented to influence a multitude of organ systems, that is, central nervous system (appetite regulation, satiety factor) and cardiovascular system (endothelial dysfunction leading to atherosclerosis). Adiponectin, circulating at a much higher concentration, exists in different molecular weight forms, essentially made up of the collagenous fraction and a globular domain, the latter being investigated minimally for its involvement in proinflammatory processes including activation of NF-κβ and endothelial adhesion molecules. The opposing actions of the two forms of adiponectin in endothelial cells have been recently demonstrated. Additionally, a local and systemic change to multimeric forms of adiponectin has gained importance. Thus detailed investigations on the potential interplay between these adipokines would likely result in better understanding of the missing links connecting CVD, adipokines, and obesity.

Adipokines, inflammation, insulin resistance, and carotid atherosclerosis in patients with rheumatoid arthritis

Introduction

Cardiovascular (CV) morbidity and mortality are increased in patients with rheumatoid arthritis (RA). Inflammation is thought to be an important factor in accelerated atherosclerosis in RA, whereas insulin resistance is a known risk factor for atherosclerosis in RA. We hypothesised that adipokines could be a link between inflammation, insulin resistance, and atherosclerosis in RA.

Methods

The common carotid artery (CCA) intima-media thickness (IMT), CCA resistive index (RI), and carotid plaques were measured by ultrasonography in 192 patients with RA. Insulin resistance was assessed by the homeostasis model assessment for insulin resistance (HOMA-IR). Serum adiponectin, leptin, resistin, tumor necrosis factor-α, and interleukin (IL)-6 concentrations were determined.

Results

The CCA RI was associated with CCA IMT and the estimated total plaque volume after adjustment for conventional CV risk factors. Among adipokines, resistin and IL-6 were correlated with inflammatory parameters. Leptin and leptin:adiponectin (L:A) ratio were correlated with metabolic risk factors, including HOMA-IR. And L:A ratio was related to the CCA RI after adjustment for conventional and nonconventional CV risk factors, including HOMA-IR, erythrocyte sedimentation rate and C-reactive protein.

Conclusion

L:A ratio was associated with HOMA-IR and carotid RI. L:A ratio might be an independent factor for predicting cardiovascular risk in patients with RA.

Pioglitazone improves fat distribution, the adipokine profile and hepatic insulin sensitivity in non-diabetic end-stage renal disease subjects on maintenance dialysis: a randomized cross-over pilot study

Background

Fat redistribution, increased inflammation and insulin resistance are prevalent in non-diabetic subjects treated with maintenance dialysis. The aim of this study was to test whether pioglitazone, a powerful insulin sensitizer, alters body fat distribution and adipokine secretion in these subjects and whether it is associated with improved insulin sensitivity.

Trial Design

This was a double blind cross-over study with 16 weeks of pioglitazone 45 mg vs placebo involving 12 subjects.

Methods

At the end of each phase, body composition (anthropometric measurements, dual energy X-ray absorptometry (DEXA), abdominal CT), hepatic and muscle insulin sensitivity (2-step hyperinsulinemic euglycemic clamp with 2H2-glucose) were measured and fasting blood adipokines and cardiometabolic risk markers were monitored.

Results

Four months treatment with pioglitazone had no effect on total body weight or total fat but decreased the visceral/sub-cutaneous adipose tissue ratio by 16% and decreased the leptin/adiponectin (L/A) ratio from 3.63×10⁻³ to 0.76×10⁻³. This was associated with a 20% increase in hepatic insulin sensitivity without changes in muscle insulin sensitivity, a 12% increase in HDL cholesterol and a 50% decrease in CRP.

Conclusions/Limitations

Pioglitazone significantly changes the visceral-subcutaneous fat distribution and plasma L/A ratio in non diabetic subjects on maintenance dialysis. This was associated with improved hepatic insulin sensitivity and a reduction of cardio-metabolic risk markers. Whether these effects may improve the outcome of non diabetic end-stage renal disease subjects on maintenance dialysis still needs further evaluation.

Trial Registration

ClinicalTrial.gov NCT01253928

Adiponectin/leptin ratio and insulin resistance in pregnancy

Objective

Pregnancy is characterized by progressive insulin resistance. The present study evaluated whether the adiponectin/leptin ratio is associated with insulin resistance in pregnancy, since this ratio has been shown to be associated with insulin resistance in obesity, type 2 diabetes mellitus, metabolic syndrome and polycystic ovary syndrome.

Methods

In this cross-sectional study, adiponectin and leptin concentrations were measured in pregnant women using enzyme-linked immunosorbent assays. Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA–IR).

Results

Mean ± SD age of the participants ( n = 74) was 30.76 ± 4.27 years, mean ± SD gestational age was 26.81 ± 3.52 weeks and median body mass index (BMI) before pregnancy was 22.68 kg/m2 (interquartile range 20.75–26.79 kg/m2). There was a significant correlation between the HOMA–IR and leptin concentration, but not between the HOMA–IR and adiponectin concentration. There was a significant inverse correlation between the HOMA–IR and adiponectin/leptin ratio. The adiponectin/leptin ratio was inversely correlated with BMI before pregnancy.

Conclusion

The adiponection/leptin ratio inversely correlates with HOMA–IR in pregnancy.

Liver enzyme and adipocytokine profiles are synergistically associated with insulin resistance: the J-SHIPP study

AIM

Alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) are associated with insulin resistance and arteriosclerotic disease. Since adiposity raises liver enzyme levels and causes insulin resistance, adipocytokines are thought to underlie the relationship between liver enzymes and insulin resistance. To clarify this hypothesis, we conducted a cross-sectional epidemiological study in a Japanese general population.

METHODS

The study subjects were 903 middle-aged to elderly persons. Plasma levels of adiponectin and leptin were measured, while other clinical parameters were obtained from personal health records of medical check-ups. Insulin resistance was assessed by a homeostasis model assessment index (HOMA-IR).

RESULTS

Plasma levels of ALT (r=0.379, p<0.001), GGT (r=0.225, p<0.001), adiponectin (r= -0.346, p<0.001) and leptin (r=0.369, p<0.001) were significantly correlated with insulin resistance even on subgroup analysis by sex. Further, any combination of liver enzymes and adipocytokines was synergistically associated with insulin resistance (p<0.001) after adjustment for possible covariates (ALT*adiponectin: β=-0.098, p<0.001, ALT*leptin: β=0.129, p<0.001, GGT*adiponectin: β=-0.054, p=0.054, GGT*leptin: β=0.126, p<0.001); however, in simple obese subjects with normal adipocytokine levels, liver enzymes were not associated with insulin resistance (mean HOMA-IR: worsened adipocytokine +/visceral obesity +, 2.01±1.14; +/-, 1.39±0.84; -/+, 1.23± 0.55; -/-, 1.03±0.57; p<0.001).

CONCLUSION

Plasma levels of ALT and GGT were independent determinants of insulin resistance only in subjects with a worsened adipocytokine profile. Use of liver enzyme levels as a marker of insulin resistance requires stratification by adipocytokine profile.

Increased levels of adipokines in bipolar disorder

Bipolar disorder (BD) is associated with considerable higher chronic medical comorbidities, overweight and obesity. Adipokines are adipocyte-derived secretory factors which have functions in immune response and seem to be associated with both BD and overweight. The aim of this study was to evaluate the plasma levels of adipokines (adiponectin, resistin and leptin) and TNF-α and its receptors (sTNFR1 and sTNFR2) in BD overweight patients in comparison with overweight controls. Thirty euthymic BD type-I patients and thirty controls matched by age, gender and body-mass index (BMI) were assessed by Mini-International Neuropsychiatric Interview, Young Mania and Hamilton Depression rating scales (YMRS and HDRS, respectively). Plasma levels of adiponectin, resistin, leptin, TNF-α and its soluble receptors were measured by ELISA. BD patients presented increased plasma levels of adiponectin (p < 0.001), leptin (p < 0.001) and sTNFR1 (p = 0.01). Plasma levels of adipokines were not correlated neither with clinical parameters nor TNF-α, sTNFR1 and sTNFR2 plasma levels. This study provides further support to the hypothesis of the immune/inflammatory imbalance in BD.