Adiponectin and leptin: potential tools in the differential diagnosis of pediatric diabetes?

Hippocampal proteins discovery of Panax quinquefolius and Acorus gramineus ameliorating cognitive impairment in diabetic rats

RATIONALE

Early diagnosis of diabetic cognitive impairment (DCI) and investigation of effective medicines are significant to prevent or delay the occurrence of irreversible dementia.

OBJECTIVES

In this study, proteomics was applied to investigate the changes of hippocampal proteins after administration of Panax quinquefolius-Acorus gramineus (PQ-AG) to DCI rats, with a view to discover the differentially expressed proteins of PQ-AG action and elucidated the potential biological relationships.

METHODS

The model and PQ-AG group rats were injected intraperitoneally with streptozotocin, and the PQ-AG group rats were continuously administered with PQ-AG. Social interaction and Morris water maze were performed to evaluate the behavior of rats on the 17th week after the model was established, and DCI rats were screened out from the model group by a screening approach. The hippocampal protein differences were investigated with proteomics in DCI and PQ-AG-treated rats.

RESULTS

The learning and memory abilities and contact duration of DCI rats were improved after 16 weeks of PQ-AG administration. Altogether, 9 and 17 differentially expressed proteins were observed in control versus DCI rats and in DCI versus PQ-AG-treated rats, respectively. Three proteins were confirmed with western blotting analyses. These proteins were mainly involved in the pathways of JAK-STAT, apoptosis, PI3K/AKT, fork-head box protein O3, fructose, and mannose metabolism.

CONCLUSIONS

This suggested that PQ-AG ameliorated cognitive impairment of diabetic rats by influencing the above pathways and providing an experimental basis for the mechanism of DCI and PQ-AG.

Association between dipeptidyl peptidase-4 inhibitors use and leptin in type 2 diabetes mellitus

BACKGROUND

Dipeptidyl peptidase-4 inhibitors (DPP-4i) provide a unique antihyperglycemic effect by regulating incretin peptides in type 2 diabetes mellitus (T2DM) patients who are inadequately controlled with insulin therapy. The aim of this study was to investigate the impact of DPP-4i on leptin concentrations in subjects with T2DM.

METHODS

Randomized controlled trials (RCTs) with comparators were systematically searched through PubMed, Embase, and the Cochrane Library. Quantitative analysis was performed with a fixed or random-effects model according to heterogeneity. Publication bias was evaluated by using the standard methods for sensitivity analysis.

RESULTS

Ten trials with 698 patients with T2DM were included. Pooled analysis demonstrated that DPP-4i did not significantly change leptin concentrations (1.31 ng/mL, 95 % CI - 0.48 to 3.10). DPP-4i exerted effects on modulating leptin levels compared to active comparators (0.21 ng/mL, 95 % CI - 1.37 to 1.78). Meta-analysis was powerful and stable after sensitivity analysis.

CONCLUSIONS

DPP-4i did not modulate leptin concentrations in T2DM and exerted no stronger effects than traditional antidiabetic agents.

Role of Adiponectin and Tumor Necrosis Factor-Alpha in the Pathogenesis and Evolution of Type 1 Diabetes Mellitus in Children and Adolescents

Type 1 diabetes mellitus (T1DM) is a complex condition caused by the destruction of pancreatic beta cells by autoimmune mechanisms. As a result, insulin deficiency and subsequent hyperglycemia occur. The aim of the present study is to investigate the role of adiponectin and tumor necrosis factor alpha (TNF-α) in the development of T1DM. The study is designed as an observational case-control study, involving 52 diabetic patients and 66 controls. Z scores for Body Mass Index (BMI), weight, height, and adiponectin and TNF-α serum levels were assessed in both groups. The T1DM group had significantly higher TNF-α levels and a significantly higher proportion of high-risk patients for inflammation based on TNF-α values as compared to the control group, while both groups had statistically similar adiponectin levels and a similar proportion of high/medium-risk patients based on adiponectin values. TNF-α plays a significant role in the pathogenesis and evolution of T1DM and it may represent an additional marker of disease progression, as well as a potential target of immunotherapeutic strategies. In the present study, no statistically significant differences were recorded in adiponectin levels neither in diabetic patients and controls, nor in high/medium severity risk diabetic patients.

Serum adipokines and vitamin D levels in patients with type 1 diabetes mellitus

INTRODUCTION

Adiponectin, leptin and resistin are adipokines that play important roles in the regulation of lipid and carbohydrate metabolism in type 2 diabetes (T2DM). However, their influence in type 1 diabetes mellitus is still unknown. The aim of this study was to measure serum adiponectin, leptin and resistin levels and to investigate their relationships with vitamin D and other clinical and laboratory parameters in patients with type 1 diabetes.

MATERIAL AND METHODS

Fifty subjects with type 1 diabetes and 50 healthy age- and sex-matched subjects were selected from the Endocrinology Outpatient Clinic of Cairo University Pediatrics Hospital. Enzyme-linked immunosorbent assay was used to measure the levels of leptin, adiponectin and resistin. Vitamin D levels were measured using electro-chemiluminescence immunoassay.

RESULTS

There were no significant differences in adiponectin and leptin levels between diabetic and control subjects (p = 0.6 and p = 0.5 respectively). Resistin levels were significantly higher in the diabetic group compared to controls (p < 0.001) and in postpubertal patients compared to prepubertal patients (p < 0.04). Serum resistin in type 1 diabetes showed a negative correlation with vitamin D (p < 0.001) and a positive correlation with glycated hemoglobin (HbA_1c) (p = 0.006), while other adipokines were not interrelated.

CONCLUSIONS

These results strongly support a role of resistin and vitamin D deficiency in the pathophysiology of type 1 diabetes. Vitamin D may be involved in resistin regulation through an unknown mechanism. Further studies are recommended to understand resistin regulation in type 1 diabetes.

Neonatal levels of adiponectin, interleukin-10 and interleukin-12 are associated with the risk of developing type 1 diabetes in childhood and adolescence: A nationwide Danish case-control study

BACKGROUND/AIM

An in-depth understanding of the early phase of type 1 diabetes (T1D) pathogenesis is important for targeting primary prevention. We examined if 14 preselected mediators of immune responses differed in neonates that later developed T1D compared to control neonates.

METHODS

The study is a case-control study with a 1:2 matching. The individuals were born between 1981 through 2002. Cases were validated using the National Patient Register and the Danish Childhood Diabetes Register. Interleukin(IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-12p70, interferon gamma, tumor necrosis factor alpha, transforming growth factor beta 1 (active form), leptin, adiponectin, c-reactive protein, mannose-binding lectin and soluble triggering receptor expressed on myeloid cells-1 were measured by using a flowmetric Luminex xMAP® technology. We tested two models both including a number of possible confounders. In the first model (model 1) we also adjusted for HLA-DQB1 genotype. A total of 1930 groups of assay-matched cases and controls (4746 individuals) were included in the statistical analyses.

RESULTS

Adiponectin was negatively associated with later risk of T1D in both models (relative change (RC), model 1: 0.95, P=0.046 and model 2: 0.95, P=0.006). IL-10 and IL-12 were both positively associated with T1D risk in the model 2 (RC, 1.19, P=0.006 and 1.07, P=0.02, respectively)-these results were borderline significant in model 1, but showed the same direction as the results from model 2.

CONCLUSIONS

Our results indicate that specific immunological signatures are already present at time of birth in children developing T1D before the age of 18years.

Swimming training attenuates the morphological reorganization of the myocardium and local inflammation in the left ventricle of growing rats with untreated experimental diabetes

Diabetic cardiomyopathy is associated with cardiac remodeling, myocardial dysfunction, low-grade inflammation, and reduced cardiac adiponectin in patients with type 1 diabetes mellitus (T1DM). Alternatively, physical exercise is an important strategy for the management of diabetes. This study aimed to investigate the influence of low-intensity swimming training in cardiac cytokines, structural remodeling, and cardiomyocyte contractile dysfunction in growing rats with untreated experimental DM. Thirty-day-old male Wistar rats were divided into four groups (n=14, per group): sedentary control (SC), exercised control (EC), sedentary diabetic (SD), and exercised diabetic (ED). Diabetes was induced by streptozotocin (60 mg kg(-1), i.p.). Animals from exercised groups swam (5 days/week, 90 min/day, loading up to 5% body weight around the animal's chest) for 8 weeks. The left ventricle (LV) was removed for molecular, morphological, and cardiomyocyte mechanical analysis. Diabetic animals presented cardiac remodeling with myocardial histoarchitectural disorganization, fibrosis, and necrosis. The capillary density was lower in diabetic animals. LV cardiomyocytes from diabetic animals exhibited more prolonged time to the peak of contraction and time to half relaxation than those from control animals. The cardiac levels of interleukin 10, nitric oxide, and total and high molecular weight (HMW) adiponectin were significantly decreased in diabetic animals. Exercise training reduced the level of TNF-α, increased capillary density, and attenuated the histopathological parameters assessed in diabetic rats. In conclusion, the cardiac structural remodeling coexists with reduced levels of total and HMW adiponectin, inflammation, and cardiomyocyte contractility dysfunction in experimental DM. More important, low-intensity swimming training attenuates part of these pathological changes, indicating the beneficial role for exercise in untreated T1DM.

Levels of adiponectin and leptin at onset of type 1 diabetes have changed over time in children and adolescents

Adiponectin and leptin are proteins secreted by the adipose tissue and have an influence on insulin sensitivity and on inflammatory markers. Altered levels could play a part in the pathogenesis of type 1 diabetes mellitus. We determined adiponectin and leptin levels over a nine-year period in children with type 1 diabetes mellitus (T1D) in relation to the increasing incidence of T1D, and studied the impact of patient status, age, gender and body mass index (BMI). Data were derived from a population-based registry of diabetic children (DanDiabKids) from 1997 to 2005. Children with newly diagnosed T1D (n = 482) were included, and healthy siblings (n = 479) were chosen as a control group. Leptin levels were significantly higher in recent years (in both patients and siblings), whereas for adiponectin, the levels were lower in recent years in the patient group. Leptin levels were lower in children with T1D (RR 0.74, p = 0.003) and in males (RR 0.52, p < 0.001) and increasing with age in both groups. For adiponectin, there was a negative association between level and age in patients. Both adipokines showed a significant correlation with BMI and lower levels in children with blood samples taken within the first 2 days after initiation of insulin treatment. There has been a change in leptin and adiponectin levels in children with or without T1D from 1997 to 2005. This is not explained by changes in BMI and may reflect changes in other factors like diet or physical activity.

Leptin, vitamin D, and cardiorespiratory fitness as risk factors for insulin resistance in European adolescents: gender differences in the HELENA Study

The purpose of this study was to identify the relevance of a set of risk factors for insulin resistance in adolescents from Europe and to consider their possible gender-specific associations. The Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) was conducted in 1053 European adolescents (mean age, 14.9 years) in a school setting in 9 countries. Three anthropometric markers of body fat and a dietary index were calculated. Total energy intake was estimated from a questionnaire. C-reactive protein, leptin, and vitamin D were assessed, and physical activity, cardiorespiratory fitness, and muscular strength were measured. Center, socioeconomic status, pubertal status, and season were used as potential confounders. The main outcome was the homeostasis model assessment used as a marker of insulin resistance. Correlations, analyses of covariance, and logistic regression models were used. In males, leptin was the only risk factor for insulin resistance after adjusting for confounders including markers of body fat (odds ratios (ORs) from 1.49 to 1.60). In females, leptin, vitamin D, and fitness were the remaining independent risk factors for insulin resistance after adjustments (OR 2.11; 95% confidential interval (CI) 1.29-3.45; OR 0.50, 95% CI 0.31-0.80; and OR 0.54, 95% CI 0.33-0.87, respectively). Our observations suggest a gender dimorphism in the identification of risk factors for high insulin resistance. Preventive strategies should focus on improving modifiable factors such as cardiorespiratory fitness and on ensuring vitamin D sufficiency. Randomized controlled trials focusing on these strategies are necessary to test their efficacy.

Physical activity, fitness, and serum leptin concentrations in adolescents

OBJECTIVE

To examine the association of physical activity and fitness with leptin concentrations in European adolescents, after taking into account several potential confounders including total body fat (TBF).

STUDY DESIGN

We conducted a cross-sectional study in a school setting for the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. This study included 902 (509 girls) adolescents aged 12.5-17.5 years. Weight, height, and TBF (sum of 6 skinfold thickness) were measured, and fat free mass and body mass index were calculated. Physical activity was assessed by accelerometry. Physical fitness was assessed by the handgrip, standing long jump, 4 × 10-m shuttle run, and 20-m shuttle run tests. Serum fasting leptin, insulin, and glucose concentrations were measured, and homeostasis model assessment was computed. Multiple linear regression models were used.

RESULTS

Vigorous physical activity and fitness tests (all P < .05) were negatively associated with leptin, independently of several confounders including TBF and homeostasis model assessment. These associations remained significant after further controlling for each other (physical activity and fitness).

CONCLUSION

These results suggest that vigorous physical activity and fitness moderate the levels of leptin concentrations, regardless of relevant confounders including TBF. Intervention programs addressed to increase high intensity physical activity and fitness as well as to assess its impact on leptin concentration are required.

Serum adipokine levels in type 1 diabetic patients: association with carotid intima media thickness

BACKGROUND

Adipokines are markers of insulin resistance and play a role in the atherosclerotic process. The association of adipokines with the macrovascular complications of type 1 diabetes mellitus (DM) needs to be determined. The aim of this study was to measure serum adiponectin, leptin, and resistin levels in type 1 DM patients and investigate their relationship with carotid intima media thickness (CIMT), a clinical marker of atherosclerosis.

METHODS

Seventy-five type 1 DM patients and 115 sex and age-matched healthy controls were included in the study. Serum adiponectin, leptin, and resistin levels were measured by the enzyme-linked immunosorbent assay (ELISA method). CIMT was assessed by Doppler ultrasonography.

RESULTS

Adiponectin levels in diabetics were higher (25.8±14.8 μg/mL vs. 5.5±7.3 μg/mL; P<0.0001) and leptin levels were lower than controls (9.4±6.2 ng/mL vs. 12.8±8.6 ng/mL; P=0.01). Resistin levels were also higher in the diabetic group compared to controls (2.1±1.4 ng/mL vs. 1.6±0.8 ng/mL; P=0.04). Adiponectin was correlated negatively with CIMT (r=-0.24, P=0.03), age (r=-0.30, P=0.02), BMI (r=-0.33, P=0.02), waist-to-hip ratio (WHR) (r=-0.38, P=0.01) and positively with creatinine (r=0.44, P=0.004). Leptin levels were correlated with total cholesterol (r=0.53, P=0.01) and high-density lipoprotein (HDL) (r=0.67, P=0.001). Resistin was correlated with CIMT (r=0.24, P=0.03) and systolic blood pressure (r=0.48, P=0.009). Multivariate analysis revealed resistin and creatinine to be independent predictors of CIMT among adiponectin, leptin, resistin, WHR, glycosylated hemoglobin (HbA1c), and creatinine.

CONCLUSIONS

Increased adiponectin correlates negatively and resistin positively with CIMT in type 1 diabetic patients, but adjusting for other known predictors reveals only resistin to be associated with subclinical atherosclerosis in this group of patients.

Role of lipoic acid on insulin resistance and leptin in experimentally diabetic rats

OBJECTIVE

We aimed to examine the changes in serum insulin and leptin levels in induced type 1 diabetes mellitus in relationship to glycemic state and lipid profiles and to clarify the role of lipoic acid (LA).

METHODS

Ninety-six male rats were equally divided into the following: a control group (normal, nondiabetic), a diabetic group induced by subcutaneous injection of alloxan (non-LA-treated), and an LA-treated diabetic group (for 4 weeks). Body weight, serum lipid profile, glucose, insulin, homeostasis model assessment-insulin resistance (HOMA-IR), and leptin were measured.

RESULTS

This study showed a significant increase in serum triacylglycerol (TG), total cholesterol, glucose levels, and HOMA-IR and a significant decrease in body weight gain, insulin, and leptin levels in the diabetic group compared to the control group. LA treatment induced a significant decrease in glucose, TG, and total cholesterol levels and significantly increased serum insulin and leptin levels in comparison with the diabetic group.

CONCLUSION

Induced diabetes resulted in insulin resistance, hyperlipidemia, and hypoleptinemia, while LA ameliorates these changes and improves insulin sensitivity.

Association of adiponectin, interleukin (IL)-1ra, inducible protein 10, IL-6 and number of islet autoantibodies with progression patterns of type 1 diabetes the first year after diagnosis

The progression of type 1 diabetes after diagnosis is poorly understood. Our aim was to assess the relation of disease progression of juvenile-onset type 1 diabetes, determined by preserved beta cell function the first year after diagnosis, with systemic cytokine concentrations and number of autoantibodies. Juvenile patients (n = 227) had a meal-stimulated C-peptide test 1 and 6 months after diagnosis. On the basis of the C-peptide course for the duration of 1-6 months, four progression groups were defined: patients with persistently low beta cell function ('stable-low'), rapid progressers, slow progressers and remitters. Serum concentrations of adiponectin, interleukin (IL)-1ra, inducible protein 10 (IP-10), IL-6 and glutamic acid decarboxylase (GAD), IA-2A and islet-cell antibodies (ICA) were measured at 1, 6 and 12 months. We found that adiponectin concentrations at 1 month predicted disease progression at 6 months (P = 0·04). Patients with low adiponectin had a higher probability of becoming remitters than rapid progressers, odds ratio 3·1 (1·3-7·6). At 6 and 12 months, adiponectin differed significantly between the groups, with highest concentrations among stable-low and rapid progressers patients (P = 0·03 and P = 0·006). IL-1ra, IP-10 and IL-6 did not differ between the groups at any time-point. The number of autoantibodies differed significantly between the groups at 1 month (P = 0·04), where rapid progressers had the largest number. There was no difference between the groups in human leucocyte antigen-associated risk. We define progression patterns distinguishing patients diagnosed with low beta cell function from those with rapid decline, slow decline or actual increase in beta cell function, pointing to different mechanisms of disease progression. We find that adiponectin concentration at 1 month predicts, and at 6 and 12 months associates with, distinct progression patterns.

The association between adiponectin/leptin ratio and diabetes type: the SEARCH for Diabetes in Youth Study

We tested the association of adiponectin/leptin ratio with diabetes type after adjusting for multiple factors in 1156 youths with newly diagnosed diabetes in the SEARCH study. Although adiponectin/leptin ratio is associated with diabetes type in youth, it is due to differences in adiponectin, but not leptin levels.

Dietary lipoic acid-dependent changes in the activity and mRNA levels of hepatic lipogenic enzymes in rats

Effects of dietary α-lipoic acid on hepatic and serum lipid concentrations and the activity and mRNA levels of lipogenic enzymes were examined in rats. Rats were fed experimental diets containing varying amounts of lipoic acid (0, 1, 2·5, 5 g/kg) for 21 d. Lipoic acid profoundly decreased serum and liver concentrations of TAG, and also lowered serum concentrations of phospholipid and NEFA, and the concentration of cholesterol in the liver. A hypoglycaemic effect of this compound was also observed. Lipoic acid dose-dependently decreased the activity and mRNA levels of fatty acid synthase, ATP-citrate lyase, glucose 6-phosphate dehydrogenase, malic enzyme and pyruvate kinase in the liver despite that reductions were considerably attenuated in the NADPH-producing enzymes. This compound also dose-dependently lowered the mRNA levels of spot 14, adiponutrin, stearoyl-CoA desaturase 1, and Δ5- and Δ6-desaturases. In addition, lipoic acid dose-dependently lowered serum concentrations of insulin and leptin, but increased those of adiponectin. Lipoic acid appeared to reduce hepatic lipogenesis and hence decreases serum and liver lipid levels. Alterations in serum concentrations of insulin and (or) adiponectin may trigger this consequence.