Leptin: in search of role(s) in human physiology and pathophysiology

Association of Leptin with Glucose Intolerance and Gestational Diabetes Mellitus in Pregnant Women: Prospective Analytical Case-Control Study

This study aimed to investigate the use of leptin as a marker for gestational diabetes by analyzing any correlation between serum leptin levels versus oral glucose tolerance tests (at 24 to 28 weeks of pregnancy) and increased body weight (during pregnancy). A total of 110 female cases (81 pregnant and 29 non-pregnant) were included in the study. The 81 pregnant cases were divided into 3 groups according to their oral glucose tolerance test results. A chi-square test was used for categorical variables. The distribution of numerical variables was tested with the Shapiro-Wilk test. ANOVA and a post-hoc Bonferroni test was used for parametric data. Kruskal-Wallis variance analysis was used for non-parametric data. The Mann-Whitney U-test was used for pairwise comparisons. Spearman correlation analysis and multivariate regression analysis were performed for the evaluation of the correlation analysis between the parameters. Oral glucose tolerance test results were compared with leptin levels with a cut-off value of 11.43 for leptin. The ROC curve demonstrated an 83.3% sensitivity and 72.1% specificity for leptin. Leptin may play a role in the pathophysiology of gestational diabetes mellitus. However, the relationship between leptin levels and maternal weight gain during pregnancy is still unknown.

Genetic predisposition of LEPR (rs1137101) gene polymorphism related to type 2 diabetes mellitus - a meta-analysis

Background: Type 2 diabetes mellitus (T2DM) is a multifaceted disease appropriate to elevated blood glucose levels resulting from decreased insulin and beta-cell activity. Using a case-control methodology, researchers have examined the relationship between polymorphisms in LEPR and T2DM in a population from south India.Materials and Methods: We conducted a genetic analysis of 311 participants, and results were accomplished using a case-control study, a meta-analysis of previous studies on LEPR was conducted, and type 2 diabetes genotype distribution across various geographical regions Malaysians, Chinese Han, Kuwait, Iran, Mongolia, and Han Chinese, Greece, Saudi, India (North India, Punjabi), (South India, Tamilnadu). The study involved 254 prospective investigations, and nine association studies were preferred according to preset criteria. Studies were assessed for quality using the Hardy-Weinberg equilibrium (HWE) and the Newcastle-Ottawa Scale (NOS). An analysis of the genetic models was conducted to determine their relationship, statistical analysis was utilized to calculate odds ratios (ORs) and matching 95% confidence intervals (CIs).Results: The LEPR-rs1137101 polymorphism in the case-control study was associated with a significant increase in the risk of type 2 diabetes. A meta-analysis revealed a connection between LEPR gene polymorphism (rs1137101) and type 2 diabetes risk. Investigators might gain a more profound thought on the significance of the identified genetic variation and its impact on the chance of developing type 2 diabetes by verifying and strengthening previously reported findings. The model of fixed effects was chosen due to the low heterogeneity, and significant associations were observed in the allelic (OR = 0.79, 95% CI [0.70-0.87]), homozygote (OR = 0.58, 95% CI [0.46-0.72]), dominant (OR = 0.66, 95% CI [0.56-0.79]), and recessive (OR = 0.83, 95% CI [0.71-0.96]) genetic models. A Begg's funnel plot and Egger's test indicated no publication bias. These findings suggest that the rs1137101 variant in the LEPR gene has been linked to a higher risk of T2DM.Conclusions: A larger sample size, however, is required for further research, and consideration of potential confounding factors is needed to validate these associations. Understanding the implications of LEPR gene polymorphisms in T2DM susceptibility may contribute to personalized treatment strategies for patients with T2DM.

Milestones in the journey towards addressing obesity; Past trials and triumphs, recent breakthroughs, and an exciting future in the era of emerging effective medical therapies and integration of effective medical therapies with metabolic surgery

The 21st century is characterized by an increasing incidence and prevalence of obesity and the burden of its associated comorbidities, especially cardiometabolic diseases, which are reaching pandemic proportions. In the late '90s, the "black box" of adipose tissue and energy homeostasis was opened with the discovery of leptin, transforming the adipose tissue from an "inert fat-storage organ" to the largest human endocrine organ and creating the basis on which more intensified research efforts to elucidate the pathogenesis of obesity and develop novel treatments were based upon. Even though leptin was eventually not proven to be the "standalone magic bullet" for the treatment of common/polygenic obesity, it has been successful in the treatment of monogenic obesity syndromes. Additionally, it shifted the paradigm of treating obesity from a condition due to "lack of willpower" to a disease due to distinct underlying biological mechanisms for which specific pharmacotherapies would be needed in addition to lifestyle modification. Subsequently, the melanocortin pathway proved to be an equally valuable pathway for the pharmacotherapy of obesity. Melanocortin receptor agonists have recently been approved for treating certain types of syndromic obesity. Other molecules- such as incretins, implicated in energy and glucose homeostasis- are secreted by the gastrointestinal tract. Glucagon-like peptide 1 (GLP-1) is the most prominent one, with GLP-1 analogs approved for common/polygenic obesity. Unimolecular combinations with other incretins, e.g., GLP-1 with gastric inhibitory polypeptide and/or glucagon, are expected to be approved soon as more effective pharmacotherapies for obesity and its comorbidities. Unimolecular combinations with other compounds and small molecules activating the receptors of these molecules are currently under investigation as promising future pharmacotherapies. Moreover, metabolic and bariatric surgery has also demonstrated impressive results, especially in the case of morbid obesity. Consequently, this broadening therapeutic armamentarium calls for a well-thought-after and well-coordinated multidisciplinary approach, for instance, through cardiometabolic expertise centers, that would ideally address effectively and cost-effectively obesity and its comorbidities, providing tangible benefits to large segments of the population.

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.

Maternal and fetal serum leptin levels and their association with maternal and fetal variables and labor: A cross-sectional study

Background

Leptin is a polypeptide hormone that may be implicated in the pathogenesis of various disorders during pregnancy. We sought to determine serum leptin levels among pregnant women and their fetuses and to investigate their association with fetal and maternal variables.

Method

452 pregnant women who attended to labor ward between January 2020 and August 2020 were included in the study. Serum leptin concentrations were measured using enzyme-linked immunosorbent assay method. Mann-Whitney U test and Spearman's correlation test were used for statistical analysis. A multivariate linear regression analysis was then performed. Significance level was considered at alpha <0.05.

Results

The median maternal and fetal serum leptin levels were 6.42 [4.16-8.51] ng/mL and 2.9 [1.03-5.36] ng/mL respectively. There was no significant correlation between maternal and fetal serum leptin levels (p = 0.064). Maternal serum leptin levels correlated positively with maternal body mass index (BMI) (r = 0.117, p = 0.005). Besides, maternal serum leptin levels were significantly higher in nulliparous women (7.57 [4.45-9.30] ng/mL vs. 6.22 [4.02-8.30] ng/mL, p = 0.037) and in women who were in active labor (6.83 [4.39-8.92] ng/mL vs. 6.25 [4.04-8.30] ng/mL, p = 0.047). Fetal serum leptin levels were significantly higher in large for gestational age (LGA) fetuses (4.81 [2.13-7.22] ng/mL vs. 2.80 [0.96-5.16] ng/mL, p = 0.003) and in fetuses with preterm premature ruptures of membranes (PPROM) (5.23 [2.42-8.07] ng/mL vs. 2.86 [1.00-5.23] ng/mL, p = 0.021).

Conclusion

Maternal serum leptin levels were influenced by maternal BMI, parity and labor. Fetal serum leptin levels were higher among LGA fetuses and in fetuses with PPROM.

Interplay between adipose tissue secreted proteins, eating behavior and obesity

Purpose

Adipokines may play an important role in the complex etiology of human obesity and its metabolic complications. Here, we analyzed the relationship between 15 adipokines, eating behavior and body-mass index (BMI).

Methods

The study included 557 participants of the Sorbs (62.1% women, 37.9% men) and 3101 participants of the population-based LIFE-Adult cohorts (53.4% women, 46.4% men) who completed the German version of the Three-Factor-Eating Questionnaire to assess the eating behavior types cognitive restraint, disinhibition and hunger. Serum levels of 15 adipokines, including adiponectin, adipocyte fatty acid-binding protein (AFABP), angiopoietin-related growth factor (AGF), chemerin, fibroblast growth factor (FGF)-19, FGF-21, FGF-23, insulin-like growth factor (IGF)-1, interleukin (IL) 10, irisin, progranulin, vaspin, pro-neurotensin (pro-NT), pro-enkephalin (PENK) and leptin were measured. Based on significant correlations between several adipokines with different eating behavior items and BMI, we conducted mediation analyses, considering the eating behavior items as potential mediation variable towards BMI.

Results

Here, we found that the positive association between chemerin, AFABP or leptin and BMI in Sorbian women was mediated by higher restraint or disinhibited eating, respectively. Additionally, in Sorbian women, the negative relation between IGF-1 and BMI was mediated by higher disinhibition and the positive link between AGF and BMI by lower disinhibition. In Sorbian men, the negative relationship between PENK and BMI was mediated by lower disinhibition and hunger, whereas the negative relation between IGF-1 and BMI was mediated by higher hunger. In the LIFE-Adult women´s cohort, associations between chemerin and BMI were mediated by decreased hunger or disinhibition, respectively, whereas relations between PENK and BMI were fully mediated by decreased disinhibition.

Conclusion

Our study suggests that adipokines such as PENK, IGF-1, chemerin, AGF, AFABP and leptin might affect the development of obesity by directly modifying individual eating behavior. Given the observational nature of the study, future experimental or mechanistic work is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02687-w.

The effect of underweight on female and male reproduction

Chronic energy deficiency can impair the hypothalamic-pituitary-gonadal (HPG) axis and lead to hypothalamic anovulation in underweight women. This review presents the syndromes related to underweight status that are associated with infertility, summarizes the underlying mechanisms, and reviews the available treatment options. Eating disorders, such as anorexia nervosa (AN), constitute the most common cause of infertility in underweight women, who, in addition, experience miscarriages, and sexual dysfunction. The relative energy deficiency in sports (RED-S; former terminology: athlete's triad) involves menstrual dysfunction due to low energy availability, which results in anovulation. Moreover, lipodystrophies, malnutrition, starvation, systematic illnesses (malignancies, endocrinopathies, infectious diseases, advanced chronic diseases, neurologic illnesses), and the utilization of drugs can cause excessive weight loss. They may result in fertility problems due to the loss of adipose tissue and the subsequent hormonal disturbances. Each of these conditions requires multidisciplinary management. Nutritional counseling should target the restoration of energy balance by increasing intake and reducing output. Medical treatment, recommended only for patients who did not respond to standard treatment, may include antipsychotics, antidepressants, or leptin administration. Finally, psychiatric treatment is considered an integral part of the standard treatment.

Association of LEPR gene polymorphisms with the risk of hepatitis B virus-related liver disease in Guangxi Chinese: A case-control study

BACKGROUND AND OBJECTIVE

Leptin receptor (LEPR) signaling inhibits apoptosis, promotes angiogenesis and proliferation, and plays a critical role in carcinogenesis. Variants of the LEPR gene may be key factors in the growth of human malignant tumors. However, the relationship between LEPR polymorphisms and hepatocellular carcinoma (HCC) has not been thoroughly investigated. Therefore, we further investigated the association between LEPR polymorphisms and the risk of chronic hepatitis B (CHB), hepatitis B virus (HBV)-related liver cirrhosis (LC), and HCC in a southern Guangxi Chinese population.

METHOD

Two LEPR polymorphisms (rs1137100 and rs1137101) were genotyped in 138 CHB patients, 136 patients with LC, 149 HCC patients, and 146 healthy controls using the SNaPshot method.

RESULTS

We did not observe any significant difference in the LEPR rs1137100 and rs1137101 polymorphisms between the groups of healthy controls and patients (all p > 0.05), regardless of genotypes, alleles, or haplotypes.

CONCLUSIONS

Our data suggest that the genetic variants of the LEPR gene are not associated with the risk of HBV-related liver diseases (CHB, LC, and HCC) in the Guangxi population. Further studies are necessary to validate these results.

Organokines in disease

Studies have linked obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD) and dementia. Their relationship to the incidence and progression of these disease states suggests an interconnected pathogenesis involving chronic low-grade inflammation and oxidative stress. Metabolic syndrome represents comorbidities of central obesity, insulin resistance, dyslipidemia, hypertension and hyperglycemia associated with increased risk of type 2 diabetes, NAFLD, atherosclerotic CVD and neurodegenerative disease. As the socioeconomic burden for these diseases has grown signficantly with an increasing elderly population, new and alternative pharmacologic solutions for these cardiometabolic diseases are required. Adipose tissue, skeletal muscle and liver are central endocrine organs that regulate inflammation, energy and metabolic homeostasis, and the neuroendocrine axis through synthesis and secretion of adipokines, myokines, and hepatokines, respectively. These organokines affect each other and communicate through various endocrine, paracrine and autocrine pathways. The ultimate goal of this review is to provide a comprehensive understanding of organ crosstalk. This will include the roles of novel organokines in normal physiologic regulation and their pathophysiological effect in obesity, metabolic syndrome, type 2 diabetes, CVD, NAFLD and neurodegenerative disorders.

A meta-analysis of associations of LEPR Q223R and K109R polymorphisms with Type 2 diabetes risk

Background

Leptin receptor (LEPR) plays a pivotal role in the control of body weight, energy metabolism, and insulin sensitivity. Various genetic association studies were performed to evaluate associations of LEPR genetic variants with type 2 diabetes (T2D) susceptibility.

Methods

A comprehensive search was conducted to identify all eligible case-control studies for examining the associations of LEPR single nucleotide polymorphisms (SNPs) Q223R (rs1137101) and K109R (rs1137100) with T2D risk. Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were used to measure the magnitudes of association.

Results

For Q223R, 13 studies (11 articles) consisting of a total of 4030 cases and 2844 controls, and for K109R 7 studies (7 articles) consisting of 3319 cases and 2465 controls were available. Under an allele model, Q223R was not significantly associated with T2D risk (OR = 1.09, 95% CI: 0.80–1.48, P-value = 0.5989), which was consistent with results obtained under four genotypic models (ranges: ORs 1.08–1.20, 95% CIs: 0.58–2.02 to 0.64–2.26; P-values, 0.3650–0.8177, which all exceeded multiplicity-adjusted α = 0.05/5 = 0.01). In addition, no significant association was found between K109R and T2D risk based on either an allele model (OR = 0.93, 95% CI: 0.85–1.03, P-value = 0.1868) or four genotypic models (ranges: ORs 0.81–0.99, 95% CIs: 0.67–0.86 to 0.97–1.26, P-values, 0.0207–0.8804 which all exceeded multiplicity-adjusted α of 0.01). The magnitudes of association for these two SNPs were not dramatically changed in subgroup analyses by ethnicity or sensitivity analyses. Funnel plot inspections as well as Begg and Mazumdar adjusted rank correlation test and Egger linear regression test did not reveal significant publication biases in main and subgroup analyses. Bioinformatics analysis predicted that both missense SNPs were functionally neutral and benign.

Conclusions

The present meta-analysis did not detect significant genetic associations between LEPR Q223R and K109R polymorphisms and T2D risk.

Investigation of TCF7L2, LEP and LEPR polymorphisms with esophageal squamous cell carcinomas

Single nucleotide polymorphisms (SNPs) in energy metabolism related gene may be key agents in the development of human malignancies. In this study, we aimed to examine the association of transcription factor 7-like 2, Leptin (LEP) and LEP receptor (LEPR) polymorphisms with esophageal squamous cell carcinoma (ESCC). A total of 507 ESCC cases and 1,496 controls were enrolled. We found that LEPR rs6588147 AA genotype was associated with ESCC risk (AA vs. GG/GA: adjusted OR=1.90, 95%CI=1.00-3.61, P=0.049). In the stratified analyses, LEPR rs6588147 G>A polymorphism increased the risk of ESCC (<63 years subgroup: AA vs. GG: adjusted OR=2.58, 95%CI=1.00-6.62, P=0.049 and AA vs. GA/GG: adjusted OR=2.71, 95%CI=1.06-6.91, P=0.038; male subgroup: AA vs. GG: adjusted OR=2.19, 95%CI=1.02-4.67, P=0.044 and AA vs. GA/GG: adjusted OR=2.26, 95%CI=1.06-4.80, P=0.035). However, LEP rs7799039 A>G decreased the risk of ESCC (≥63 years subgroup: GG vs. AA: adjusted OR=0.47, 95%CI=0.23-0.95, P=0.035 and GG vs. AA/AG: adjusted OR=0.48, 95%CI=0.24-0.96, P=0.038; BMI≥24 kg/m² subgroup: AG vs. AA: adjusted OR=0.66, 95%CI=0.45-0.99, P=0.044). In addition, LEPR rs1137101 G>A polymorphism decreased ESCC risk in some subgroups (ever smoking subgroup: GA vs. GG: adjusted OR=0.66, 95%CI=0.44-1.00, P=0.049; ever drinking subgroup: GA vs. GG: adjusted OR=0.54, 95%CI=0.31-0.95, P=0.031 and GA/AA vs. GG: adjusted OR=0.54, 95%CI=0.31-0.93, P=0.027). Our findings suggest that LEPR rs6588147 G>A polymorphism is associated with the increased risk of ESCC; however, LEP rs7799039 A>G and LEPR rs1137101 G>A polymorphisms may be protective factors for ESCC.

Oxytocin system dysfunction as a common mechanism underlying metabolic syndrome and psychiatric symptoms in schizophrenia and bipolar disorders

There is growing interest in using intranasal oxytocin (OT) to treat social dysfunction in schizophrenia and bipolar disorders (i.e., psychotic disorders). While OT treatment results have been mixed, emerging evidence suggests that OT system dysfunction may also play a role in the etiology of metabolic syndrome (MetS), which appears in one-third of individuals with psychotic disorders and associated with increased mortality. Here we examine the evidence for a potential role of the OT system in the shared risk for MetS and psychotic disorders, and its prospects for ameliorating MetS. Using several studies to demonstrate the overlapping neurobiological profiles of metabolic risk factors and psychiatric symptoms, we show that OT system dysfunction may be one common mechanism underlying MetS and psychotic disorders. Given the critical need to better understand metabolic dysregulation in these disorders, future OT trials assessing behavioural and cognitive outcomes should additionally include metabolic risk factor parameters.

The association between level of maternal serum leptin in the third trimester and the occurrence of moderate preterm labor

OBJECTIVE

We aimed to investigate the relationship between the level of maternal serum leptin and the occurrence of moderate preterm labor.

MATERIAL AND METHODS

This was a case control study conducted on pregnant women referred to Al-Zahra Hospital in Rasht, north of Iran in 2013. Cases included 30 moderate preterm delivering women and 30 control pregnant women with the same gestational age. The maternal serum leptin was measured for each mother at the time of entering the study.

RESULTS

The mean serum leptin in the control group (56.66±34.18) was significantly higher than the preterm (33.65±16.70) group. There were no significant differences between the groups in terms of body mass index and age. Logistic regression revealed that age and body mass index did not have a significant relationship to moderate preterm birth. However, an increased leptin level as low as 1 microgram per liter was associated with the risk of moderate preterm birth incidence (OR: 0.973, CI: 0.948-0.997).

CONCLUSION

Higher levels of leptin in pregnant women are associated with a decreased risk of moderate preterm birth. Further investigations are recommended with a larger sample size.

Predictors of leptin concentration and association with cardiovascular risk in patients with coronary artery disease: results from the AtheroGene study

CONTEXT

Leptin is produced in white adipose tissue, but also in human coronary atherosclerotic lesions.

OBJECTIVE

The aim of this study is to assess the prognostic value of leptin in patients with proven coronary artery disease (CAD) (N = 1907).

METHODS

AtheroGene is a contemporary CAD cohort study (N = 3229). Median follow-up time was 3.8 (Quartile 1/3 with 2.8/4.9) years.

RESULTS

Leptin concentration was associated with a hazard ratio (HR) for the fully adjusted model of HR = 1.32 in women but was not significant in men. The endpoint cardiovascular death and non-fatal myocardial infarction was observed in 167 patients.

CONCLUSION

In women with known CAD, increased leptin concentration is useful for predicting cardiovascular death and non-fatal myocardial infarction.

Metformin Decreases Thyroid Volume and Nodule Size in Subjects with Insulin Resistance: A Preliminary Study

OBJECTIVE

The aim of this study was to investigate the effects of metformin on thyroid volume and nodule size.

SUBJECTS AND METHODS

Prospective data were gathered on 100 newly diagnosed subjects with insulin resistance (68 female, 32 male) between August 2008 and May 2010. Each subject followed a standard diet and exercise program, and received 1,700 mg/day of metformin therapy for 6 months. The height, weight, waist circumference (WC) and thyroid hormone levels of each subject were measured. Additionally, the dimensions of the thyroid lobes and maximum diameter of each thyroid nodule were determined by ultrasonography. BMI and thyroid volumes were also calculated. Insulin resistance was estimated by homeostasis model assessment. All these parameters were measured at the beginning and at the end of the treatment period.

RESULTS

BMI and WC decreased significantly after metformin therapy (34.5 ± 5.1 vs. 32.7 ± 4.8, p < 0.0001, and 106.3 ± 11.8 vs. 101.8 ± 19.0 cm, p = 0.008, respectively). Insulin resistance also decreased after metformin therapy (4.5 ± 1.9 vs. 2.9 ± 1.7, p < 0.0001). The mean thyroid volume (22.5 ± 11.2 vs. 20.3 ± 10.4 ml, p < 0.0001) and mean thyroid nodule size (12.9 ± 7.6 vs. 11.7 ± 7.2 mm, p < 0.0001) also decreased after treatment.

CONCLUSION

In subjects with insulin resistance, metformin therapy significantly decreased thyroid volume and nodule size.

Association Between Gingival Crevicular Fluid Leptin Levels and Periodontal Status - A Biochemical Study on Indian Patients

AIM

The present study was carried out to evaluate and compare the gingival crevicular fluid (GCF) concentrations of leptin in periodontally healthy and diseased subjects, to compare GCF leptin levels with respect to Body Mass Index (BMI) among the study groups and essentially to obtain an insight into leptin's possible role in the initiation and progression of periodontal disease.

MATERIALS AND METHODS

A total of 60 subjects; both males and females, based on their body mass index were selected for the study. They were categorized into three groups of 20 subjects each, based on their periodontal status, as follows: Group I (clinically healthy periodontium); Group II (gingivitis); Group III (chronic periodontitis). GCF samples of 1 μl were collected extra-crevicularly using black color-coded 1-5 μl calibrated volumetric microcapillary pipettes from one site in each person, and samples were analyzed for leptin using a commercially available ELISA kit.

RESULTS

The concentration of leptin in GCF of patients in Group I (2272.25 pg/mL) was statistically higher (p < 0.001) than in those of Group II (1421.86 pg/mL) and Group III (1160.67 pg/mL). No statistically significant difference was found when comparing the mean values of leptin between BMI groups in each study group.

CONCLUSION

As periodontal disease progressed, there was a substantial decrease in the gingival crevicular fluid leptin concentration. This suggests a protective role of leptin with regard to periodontal health.

Sustained high levels of serum leptin rather than IL-6 observed in patients with postpartum thyroiditis during their first postpartum year

The purpose of the study is to explore the roles of leptin and interleukin-6 (IL-6) during the first postpartum year in the occurrence and development of postpartum thyroiditis (PPT). We retrospectively collected serum samples from 57 PPT patients consisting of 34 overt PPT (O-PPT) and 23 subclinical PPT (S-PPT) in addition to 37 healthy postpartum women at four postpartum time points, i.e., 3-day and 3, 6, 12-month postpartum. Serum leptin and IL-6 levels were measured by radioimmunoassay and ELISA assay, respectively. Leptin level and leptin/BMI (LEP/BMI) ratio were higher in PPT patients than in control during the first postpartum year, but were not significantly different between O-PPT and S-PPT. However, a similar trend but did not reach significant difference in IL-6 level was observed during the postpartum period in PPT patients and control women. We conclude that a sustained high level of serum leptin after delivery may be involved in the pathogenesis of PPT. IL-6 does not contribute to the development of PPT.

Diurnal intermittent fasting during Ramadan: the effects on leptin and ghrelin levels

We aimed to assess the effect of Islamic intermittent fasting, during and outside of Ramadan, on plasma levels of leptin and ghrelin while controlling for several potential confounding variables. Eight healthy male volunteers with a mean age of 26.6±4.9 years reported to the sleep disorders center (SDC) at King Saud University on four occasions: 1) adaptation; 2) 4 weeks before Ramadan while performing Islamic fasting for 1 week (baseline fasting) (BLF); 3) 1 week before Ramadan (non-fasting baseline) (BL); and 4) during the second week of Ramadan while fasting. Plasma leptin and ghrelin levels were measured using enzyme-linked immunoassays at 22:00, 02:00, 04:00, 06:00, and 11:00. During BLF, there were significant reductions in plasma leptin concentrations at 22:00 and 02:00 compared with the baseline concentrations (at 22:00: 194.2±177.2 vs. 146.7±174.5; at 02:00: 203.8±189.5 vs. 168.1±178.1; p<0.05). During Ramadan, there was a significant reduction in plasma leptin levels at 22:00 (194.2±177.2 vs. 132.6±130.4, p<0.05). No significant difference in plasma ghrelin concentrations was detected during the BL, BLF, or Ramadan periods. Cosinor analyses of leptin and ghrelin plasma levels revealed no significant changes in the acrophases of the hormones during the three periods. The nocturnal reduction in plasma leptin levels during fasting may be the result of the changes in meal times during fasting.

Obesity and thyroid cancer: epidemiologic associations and underlying mechanisms

The incidence of thyroid cancer has been rising over the past few decades along with a parallel increase in obesity. Observational studies have provided evidence for a potential association between the two. By contrast, clinical data for a link between type 2 diabetes mellitus, a condition strongly associated with obesity, and thyroid cancer are limited and largely not supportive of such an association. Obesity leads to hypoadiponectinemia, a pro-inflammatory state, and insulin resistance, which, in turn, leads to high circulating insulin and insulin-like growth factor-1 levels, thereby possibly increasing the risk for thyroid cancer. Thus, insulin resistance possibly plays a pivotal role in underlying the observed association between obesity and thyroid cancer, potentially leading to the development and/or progression of thyroid cancer, through its interconnections with other factors including insulin-like growth factor-1, adipocytokines/cytokines and thyroid-stimulating hormone. In this review, epidemiological and clinical evidence and potential mechanisms underlying the proposed association between obesity and thyroid cancer risk are reviewed. If the association between obesity and thyroid cancer demonstrated in observational studies proves to be causal, targeting obesity (and/or downstream mediators of risk) could be of importance in the prevention and management of thyroid cancer.

Analysis of Gln223Agr polymorphism of Leptin Receptor Gene in type II diabetic mellitus subjects among Malaysians

Leptin is known as the adipose peptide hormone. It plays an important role in the regulation of body fat and inhibits food intake by its action. Moreover, it is believed that leptin level deductions might be the cause of obesity and may play an important role in the development of Type 2 Diabetes Mellitus (T2DM), as well as in cardiovascular diseases (CVD). The Leptin Receptor (LEPR) gene and its polymorphisms have not been extensively studied in relation to the T2DM and its complications in various populations. In this study, we have determined the association of Gln223Agr loci of LEPR gene in three ethnic groups of Malaysia, namely: Malays, Chinese and Indians. A total of 284 T2DM subjects and 281 healthy individuals were recruited based on International Diabetes Federation (IDF) criteria. Genomic DNA was extracted from the buccal specimens of the subjects. The commercial polymerase chain reaction (PCR) method was carried out by proper restriction enzyme MSP I to both amplify and digest the Gln223Agr polymorphism. The p-value among the three studied races was 0.057, 0.011 and 0.095, respectively. The values such as age, WHR, FPG, H_bA_1C, LDL, HDL, Chol and Family History were significantly different among the subjects with Gln223Agr polymorphism of LEPR (p < 0.05).

[Elevated levels of leptin and LDL-cholesterol in patients with well controlled congenital adrenal hyperplasia]

OBJECTIVE

The objective of this study was to evaluate patients with classic CAH before and after treatment with glucocorticoids/mineralocorticoid and compare the metabolic profile of the well controlled (WC) and poorly controlled (PC) group.

SUBJECTS AND METHODS

We selected newly diagnosed patients and patients monitored for CAH, classical form, regularly using or not glucocorticoids/mineralocorticoid in the Genetics Service Hupes-UFBA, seen from March/2004 to May/2006. All patients underwent detailed clinical evaluation and laboratory tests (glucose, sodium and potassium; total cholesterol, HDL, LDL, triglycerides and uric acid; leptin, 17-hydroxyprogesterone, total testosterone, C peptide, and insulin). Patients with normal androgens were classified as well controlled (WC), and those with high levels of androgens either using or not glucocorticoids/mineralocorticoids were classified as poorly controlled (PC).

RESULTS

We studied 41 patients with CAH: 11 in the WC group and 30 in PC group. Leptin and LDL cholesterol levels were higher in WC than in the PC group (p < 0.05). Uric acid values were lower in WC compared with the PC group (p < 0.05).

CONCLUSION

Adequate control of CAH with steroids seems safe, as it is associated with only mild changes in lipid profile and leptin values. No other metabolic abnormality was associated with glucocorticoid use. The reason for lower uric acid levels found in WC CAH patients is unknown and should be further studied.

Mid-pregnancy maternal leptin levels, birthweight for gestational age and preterm delivery

OBJECTIVE

Maternal blood leptin levels are positively associated with adiposity. Recent studies suggest that leptin is also abundantly produced by the placenta and may function as a regulator of foetal growth. Our goal was to examine mid-pregnancy levels of leptin in maternal blood in relation to birthweight for gestational age (BW/GA) and timing of delivery after accounting for maternal prepregnancy body mass index (prepreg-BMI) and pregnancy complications.

PATIENTS

Data were from 1304 subcohort mother/infant pairs who participated in the Pregnancy Outcomes and Community Health (POUCH) Study (1998-2004).

MEASUREMENTS

Leptin levels, measured at 16-27 weeks' gestation, were log-transformed. Geometric mean (GMean) leptin levels were estimated by weighted linear regression with gestational age at blood draw as a covariate. GMean was re-transformed to the original scale for reporting.

RESULTS

Using the GMeans leptin in mothers of term appropriate-for-gestational age (AGA) neonates as the referent (25·2 μg/l), we observed lower levels in mothers of preterm-AGA (21·9 μg/l), term small-for-gestational age (SGA) (20·3 μg/l) and preterm-SGA neonates (21·7 μg/l). Results were largely unchanged after adjustment for prepreg-BMI. Leptin levels were higher in mothers who delivered large-for-gestational age (LGA) neonates, both preterm (33·6 μg/l) and term (29·1 μg/l), but the GMeans were markedly attenuated after adjustment for prepreg-BMI.

CONCLUSION

The association between BW/GA and maternal leptin levels after adjustment for prepreg-BMI may represent: (i) a residual effect of maternal adiposity that is not fully captured by BMI; and/or (ii) variation in placental leptin levels entering the maternal circulation. In conclusion, mid-pregnancy maternal blood leptin levels may be an early indicator of foetal growth status.

Role of the cytoskeleton in muscle transcriptional responses to altered use

In this work, the interaction between the loss of a primary component of the skeletal muscle cytoskeleton, desmin, and two common physiological stressors, acute mechanical injury and aging, were investigated at the transcriptional, protein, and whole muscle levels. The transcriptional response of desmin knockout (des(-/-)) plantarflexors to a bout of 50 eccentric contractions (ECCs) showed substantial overlap with the response in wild-type (wt) muscle. However, changes in the expression of genes involved in muscle response to injury were blunted in adult des(-/-) muscle compared with wt (fold change with ECC in des(-/-) and wt, respectively: Mybph, 1.4 and 2.9; Xirp1, 2.2 and 5.7; Csrp3, 1.8 and 4.3), similar to the observed blunted mechanical response (torque drop: des(-/-) 30.3% and wt 55.5%). Interestingly, in the absence of stressors, des(-/-) muscle exhibited elevated expression of many these genes compared with wt. The largest transcriptional changes were observed in the interaction between aging and the absence of desmin, including many genes related to slow fiber pathway (Myh7, Myl3, Atp2a2, and Casq2) and insulin sensitivity (Tlr4, Trib3, Pdk3, and Pdk4). Consistent with these transcriptional changes, adult des(-/-) muscle exhibited a significant fiber type shift from fast to slow isoforms of myosin heavy chain (wt, 5.3% IIa and 71.7% IIb; des(-/-), 8.4% IIa and 61.4% IIb) and a decreased insulin-stimulated glucose uptake (wt, 0.188 μmol/g muscle/20 min; des(-/-), 0.085 μmol/g muscle/20 min). This work points to novel areas of influence of this cytoskeletal protein and directs future work to elucidate its function.

Association of LEP G2548A and LEPR Q223R polymorphisms with cancer susceptibility: evidence from a meta-analysis

BACKGROUND

Numerous epidemiological studies have examined associations of genetic variations in LEP (G2548A, -2548 nucleotide upstream of the ATG start site) and LEPR (Q223R, nonsynonymous SNP in exon 6) with cancer susceptibility; however, the findings are inconsistent. Therefore, we performed a meta-analysis to comprehensively evaluate such associations.

METHODS

We searched published literature from MEDLINE, EMBASE, Web of Science and CBM for eligible publications. We also assessed genotype-based mRNA expression data from HapMap for rs7799039 (G2548A) and rs1137101 (Q223R) in normal cell lines derived from 270 subjects with different ethnicities.

RESULTS

The final analysis included 16 published studies of 6569 cases and 8405 controls for the LEP G2548A and 19 studies of 7504 cases and 9581 controls for the LEPR Q223R. Overall, LEP G2548A was statistically significantly associated with an increased risk of overall cancer (AA vs. GG: OR=1.27, 95% CI=1.05-1.54; recessive model: OR=1.19, 95% CI=1.00-1.41). Further stratifications by cancer type showed an increased risk for prostate cancer (recessive model: OR=1.26, 95% CI=1.05-1.51) but not for other cancers. For LEPR Q223R, no statistical evidence for an association with risk of cancer was found for all; however, further stratification by ethnicity showed an increased risk for Africans but not for other ethnicities. No significantly differences in LEP and LEPR mRNA expression were found among genotypes or by ethnicity.

CONCLUSIONS

Despite some limitations, this meta-analysis found some statistical evidence for an association between the LEP 2548AA genotype and overall risk of cancer, particularly for prostate cancer, but given this variant did not have an effect on mRNA expression, this association warrants additional validation in large and well-designed studies.

Transfusion of CXCR4-primed endothelial progenitor cells reduces cerebral ischemic damage and promotes repair in db/db diabetic mice

This study investigated the role of stromal cell-derived factor-1α (SDF-1α)/CXC chemokine receptor 4 (CXCR4) axis in brain and endothelial progenitor cells (EPCs), and explored the efficacy of CXCR4 primed EPCs in treating ischemic stroke in diabetes. The db/db diabetic and db/+ mice were used in this study. Levels of plasma SDF-1α and circulating CD34+CXCR4+ cells were measured. Brain SDF-1α and CXCR4 expression were quantified at basal and after middle cerebral artery occlusion (MCAO). In in vitro study, EPCs were transfected with adenovirus carrying null (Ad-null) or CXCR4 (Ad-CXCR4) followed with high glucose (HG) treatment for 4 days. For pathway block experiments, cells were pre-incubated with PI3K inhibitor or nitric oxide synthase (NOS) inhibitor for two hours. The CXCR4 expression, function and apoptosis of EPCs were determined. The p-Akt/Akt and p-eNOS/eNOS expression in EPCs were also measured. In in vivo study, EPCs transfected with Ad-null or Ad-CXCR4 were infused into mice via tail vein. On day 2 and 7, the cerebral blood flow, neurologic deficit score, infarct volume, cerebral microvascular density, angiogenesis and neurogenesis were determined. We found: 1) The levels of plasma SDF-1α and circulating CD34+CXCR4+ cells were decreased in db/db mice; 2) The basal level of SDF-1α and MCAO-induced up-regulation of SDF-1α/CXCR4 axis were reduced in the brain of db/db mice; 3) Ad-CXCR4 transfection increased CXCR4 expression in EPCs and enhanced EPC colonic forming capacity; 4) Ad-CXCR4 transfection prevented EPCs from HG-induced dysfunction (migration and tube formation) and apoptosis via activation of PI3K/Akt/eNOS signal pathway; 4) Ad-CXCR4 transfection enhanced the efficacy of EPC infusion in attenuating infarct volume and promoting angiogenesis and neurogenesis. Our data suggest that Ad-CXCR4 primed EPCs have better therapeutic effects for ischemia stroke in diabetes than unmodified EPCs do.

Leptin as a modulator of neuroendocrine function in humans

Leptin, a peptide hormone secreted by adipocytes in proportion of the amount of energy stored in fat, plays a central role in regulating human energy homeostasis. In addition, leptin plays a significant permissive role in the physiological regulation of several neuroendocrine axes, including the hypothalamic-pituitary-gonadal, -thyroid, -growth hormone, and -adrenal axes. Decreased levels of leptin, also known as hypoleptinemia, signal to the brain a state of energy deprivation. Hypoleptinemia can be a congenital or acquired condition, and is associated with alterations of the aforementioned axes aimed at promoting survival. More specifically, gonadotropin levels decrease and become less pulsatile under conditions of energy deprivation, and these changes can be at least partially reversed through leptin administration in physiological replacement doses. Similarly, leptin deficiency is associated with thyroid axis abnormalities including abnormal levels of thyrotropin-releasing hormone, and leptin administration may at least partially attenuate this effect. Leptin deficiency results in decreased insulin-like growth factor 1 levels which can be partially ameliorated through leptin administration, and leptin appears to have a much more pronounced effect on the growth of rodents than that of humans. Similarly, adrenal axis function is regulated more tightly by low leptin in rodents than in humans. In addition to congenital leptin deficiency, conditions that may be associated with decreased leptin levels include hypothalamic amenorrhea, anorexia nervosa, and congenital or acquired lipodystrophy syndromes. Accumulating evidence from proof of concept studies suggests that leptin administration, in replacement doses, may ameliorate neuroendocrine abnormalities in individuals who suffer from these conditions.

Leptin in anorexia and cachexia syndrome

Leptin is a product of the obese (OB) gene secreted by adipocytes in proportion to fat mass. It decreases food intake and increases energy expenditure by affecting the balance between orexigenic and anorexigenic hypothalamic pathways. Low leptin levels are responsible for the compensatory increase in appetite and body weight and decreased energy expenditure (EE) following caloric deprivation. The anorexia-cachexia syndrome is a complication of many chronic conditions including cancer, chronic obstructive pulmonary disease, congestive heart failure, chronic kidney disease, and aging, where the decrease in body weight and food intake is not followed by a compensatory increase in appetite or decreased EE. Crosstalk between leptin and inflammatory signaling known to be activated in these conditions may be responsible for this paradox. This manuscript will review the evidence and potential mechanisms mediating changes in the leptin pathway in the setting of anorexia and cachexia associated with chronic diseases.

Arginine 16 Glycine Polymorphism in β2-Adrenergic Receptor Gene is Associated with Obesity, Hyperlipidemia, Hyperleptinemia, and Insulin Resistance in Saudis

Background. Several studies have shown an association between codon 16 polymorphism of the β2AR gene and obesity. Methods. We studied the association between Arg16Gly polymorphism and obesity and its influence on anthropometric parameters, lipids, insulin resistance and leptin in Saudi individuals. The study group included 329 individuals (males: 109 and females: 220). Metabolic parameters, including glucose, lipids, insulin, and leptin were analyzed and anthropometric parameters including waist and hip circumference, waist/hip (W/H) ratio, and body mass index (BMI) were measured and HOMA-IR was calculated. Genotyping was conducted by DNA sequencing of 353 bp fragments, carrying the Arg16Gly polymorphic site. Results and Conclusion. Overweight and obese subjects had a significantly higher frequency of Gly16 (0.375 and 0.38, resp.) compared with normal-weight subjects (0.200). In addition, subjects carrying Gly16 allele regardless of their BMI had greater waist and hip circumference, W/H ratio, plasma lipids, leptin, glucose level, and insulin resistance as judged from the HOMA-IR, compared to those with the wild-type allele. The findings of this study show a significant association between the Arg16Gly polymorphism in β2AR gene and the development of insulin resistance, overweight, and obesity in Saudi populations with an influence on the levels of lipid and leptin.

Bone mineral density and body composition in girls with idiopathic central precocious puberty before and after treatment with a gonadotropin-releasing hormone agonist

OBJECTIVES

Idiopathic central precocious puberty and its postponement with a (gonadotropin-releasing hormone) GnRH agonist are complex conditions, the final effects of which on bone mass are difficult to define. We evaluated bone mass, body composition, and bone remodeling in two groups of girls with idiopathic central precocious puberty, namely one group that was assessed at diagnosis and a second group that was assessed three years after GnRH agonist treatment.

METHODS

The precocious puberty diagnosis and precocious puberty treatment groups consisted of 12 girls matched for age and weight to corresponding control groups of 12 (CD) and 14 (CT) girls, respectively. Bone mineral density and body composition were assessed by dual X-ray absorptiometry. Lumbar spine bone mineral density was estimated after correction for bone age and the mathematical calculation of volumetric bone mineral density. CONEP: CAAE-0311.0.004.000-06.

RESULTS

Lumbar spine bone mineral density was slightly increased in individuals diagnosed with precocious puberty compared with controls; however, after correction for bone age, this tendency disappeared (CD = -0.74 + 0.9 vs. precocious puberty diagnosis = -1.73 + 1.2). The bone mineral density values of girls in the precocious puberty treatment group did not differ from those observed in the CT group.

CONCLUSION

There is an increase in bone mineral density in girls diagnosed with idiopathic central precocious puberty. Our data indicate that the increase in bone mineral density in girls with idiopathic central precocious puberty is insufficient to compensate for the marked advancement in bone age observed at diagnosis. GnRH agonist treatment seems to have no detrimental effect on bone mineral density.

Leptin in human physiology and pathophysiology

Leptin, discovered through positional cloning 15 years ago, is an adipocyte-secreted hormone with pleiotropic effects in the physiology and pathophysiology of energy homeostasis, endocrinology, and metabolism. Studies in vitro and in animal models highlight the potential for leptin to regulate a number of physiological functions. Available evidence from human studies indicates that leptin has a mainly permissive role, with leptin administration being effective in states of leptin deficiency, less effective in states of leptin adequacy, and largely ineffective in states of leptin excess. Results from interventional studies in humans demonstrate that leptin administration in subjects with congenital complete leptin deficiency or subjects with partial leptin deficiency (subjects with lipoatrophy, congenital or related to HIV infection, and women with hypothalamic amenorrhea) reverses the energy homeostasis and neuroendocrine and metabolic abnormalities associated with these conditions. More specifically, in women with hypothalamic amenorrhea, leptin helps restore abnormalities in hypothalamic-pituitary-peripheral axes including the gonadal, thyroid, growth hormone, and to a lesser extent adrenal axes. Furthermore, leptin results in resumption of menses in the majority of these subjects and, in the long term, may increase bone mineral content and density, especially at the lumbar spine. In patients with congenital or HIV-related lipoatrophy, leptin treatment is also associated with improvements in insulin sensitivity and lipid profile, concomitant with reduced visceral and ectopic fat deposition. In contrast, leptin's effects are largely absent in the obese hyperleptinemic state, probably due to leptin resistance or tolerance. Hence, another emerging area of research pertains to the discovery and/or usefulness of leptin sensitizers. Results from ongoing studies are expected to further increase our understanding of the role of leptin and the potential clinical applications of leptin or its analogs in human therapeutics.

Effect of LEPR Gln223Arg polymorphism on breast cancer risk in different ethnic populations: a meta-analysis

Leptin and leptin receptor have been implicated in processes leading to breast cancer initiation and progression. An A to G transition mutation in codon 223, in exon 6 of the leptin receptor gene (LEPR) can result in glutamine to arginine substitution (Gln223Arg). A variety of case-control studies have been published evaluating the association between LEPR Gln223Arg polymorphism and breast cancer. However, published studies have yielded contradictory conclusions. This meta-analysis enrolled eight studies to estimate the overall risk of LEPR Gln223Arg polymorphism associated with breast cancer. The pooled ORs were performed for codominant model (Arg/Arg versus Gln/Gln; Arg/Gln versus Gln/Gln), dominant model (Arg/Arg + Arg/Gln versus Gln/Gln), recessive model (Arg/Arg versus Arg/Gln + Gln/Gln). Overall significantly elevated breast cancer risk was found for recessive model (OR 1.32, 95% CI 1.03-1.69) and for genotype Arg/Gln versus Gln/Gln (OR 1.16, 95% CI 1.01-1.34). In the stratified analysis by ethnicity, significantly increased risks were also found among Africans for genotype Arg/Arg versus Gln/Gln: OR 1.86, 95% CI 1.28-2.71, Arg/Gln versus Gln/Gln: OR 1.48, 95% CI 1.10-1.99, dominant model: OR 1.60, 95% CI 1.21-2.11 and recessive model: OR 1.48, 95% CI 1.07-2.05; for Asians, Arg/Arg versus Gln/Gln: OR 6.79, 95% CI 3.42-13.47 and dominant model: OR 2.03, 95% CI 1.42-2.90. However, no significantly increased risk was found among Europeans for all genetic models. In conclusion, the LEPR 223Arg is a low-penetrant risk for developing breast cancer, especially for black African women.

Manganese superoxide dismutase expression in endothelial progenitor cells accelerates wound healing in diabetic mice

Amputation as a result of impaired wound healing is a serious complication of diabetes. Inadequate angiogenesis contributes to poor wound healing in diabetic patients. Endothelial progenitor cells (EPCs) normally augment angiogenesis and wound repair but are functionally impaired in diabetics. Here we report that decreased expression of manganese superoxide dismutase (MnSOD) in EPCs contributes to impaired would healing in a mouse model of type 2 diabetes. A decreased frequency of circulating EPCs was detected in type 2 diabetic (db/db) mice, and when isolated, these cells exhibited decreased expression and activity of MnSOD. Wound healing and angiogenesis were markedly delayed in diabetic mice compared with normal controls. For cell therapy, topical transplantation of EPCs onto excisional wounds in diabetic mice demonstrated that diabetic EPCs were less effective than normal EPCs at accelerating wound closure. Transplantation of diabetic EPCs after MnSOD gene therapy restored their ability to mediate angiogenesis and wound repair. Conversely, siRNA-mediated knockdown of MnSOD in normal EPCs reduced their activity in diabetic wound healing assays. Increasing the number of transplanted diabetic EPCs also improved the rate of wound closure. Our findings demonstrate that cell therapy using diabetic EPCs after ex vivo MnSOD gene transfer accelerates their ability to heal wounds in a mouse model of type 2 diabetes.

Serum leptin in overt and subclinical hypothyroidism: effect of levothyroxine treatment and relationship to menopausal status and body composition

BACKGROUND

The relationship between thyroid status, including subclinical hypothyroidism (SH) and serum leptin is controversial or uncertain. Therefore we evaluated serum leptin in SH and overt hypothyroidism (OH) and determined the effects of levothyroxine (LT(4)) replacement on serum leptin in these disorders.

METHODS

Serum leptin, thyrotropin (TSH), free thyroxine, insulin, glucose, and body composition parameters were compared in 55 SH, 20 OH, and 28 euthyroid (EU) pre- and postmenopausal women. In addition, the effect of LT(4) treatment on serum leptin in SH and OH was assessed.

RESULTS

The mean +/- SD (median) serum leptin concentrations in the OH and SH groups were higher than in the EU group (35.1 +/- 27.2 [33.0] and 36.6 +/- 21.9 [30.6] ng/mL, respectively, vs. 23.2 +/- 19.3 [17.9] ng/mL, p = 0.011), but the difference was only significant in postmenopausal women. The body mass index (BMI), fat mass index (FMI), and the homeostasis model assessment-insulin resistance (HOMA-IR) index values were not different among these groups. In premenopausal women there was no correlation between leptin, BMI, or FMI and serum TSH levels (r(s) = 0.009, p = 0.474; r(s) = 0.043, p = 0.367; r(s) = 0.092, p = 0.232). In the postmenopausal women, the partial correlation coefficient between TSH and leptin was present, even when controlling for BMI (r(s) = 0.297, p = 0.042) and FMI (r(s) = 0.275, p = 0.050). LT(4) treatment was associated with a reduction of serum leptin concentrations in the OH group (p = 0.008). In SH group there were no differences between LT(4) replacement or no treatment, since a fall in serum leptin levels was detected in both SH subgroups, despite a more pronounced fall with LT(4) use. Treatment of the SH and OH groups with LT(4) did not influence HOMA-IR index or body composition.

CONCLUSIONS

Serum leptin concentrations are elevated in postmenopausal women with SH or OH. A relationship between thyroid status and serum leptin is further supported by the fact that LT(4) treatment, to restore the EU status, reduced serum leptin levels in OH in the absence of significant effects on BMI. In women, hypothyroidism influences either leptin secretion or degradation and this effect is more pronounced in postmenopausal than in premenopausal women.

Modulating effect of leptin on basal and follicle stimulating hormone stimulated steroidogenesis in cultured human lutein granulosa cells

BACKGROUND

In vitro data have shown conflicting results in terms of the effect of leptin on granulosa cells steroidogenesis.

AIM

The aim of the present study was to investigate the effect of low and high doses of leptin on basal and FSH-induced steroids secretion by human luteinized granulosa cells in culture.

MATERIALS AND METHODS

Granulosa cells were obtained from normal women undergoing in vitro fertilization (IVF) treatment and were cultured in serum-free conditions for 72 h. A one-way analysis of variance design was set to study the effect of leptin on basal and FSH-induced steroidogenesis.

RESULTS

Leptin affected basal estradiol and progesterone secretion in a dose-related manner. In particular, leptin at low concentrations stimulated the secretion of estradiol (1 and 10 ng/ml) and progesterone (10 ng/ml), while at a high concentration (100 ng/ml) it suppressed the secretion of both steroids. A dose-related effect of leptin on FSH-induced steroidogenesis was not evident, since only the suppressive effect of the high concentration of leptin (100 ng/ml) reached statistical significance for both steroids.

CONCLUSIONS

These results demonstrate that leptin affects the secretion of steroids in luteinized granulosa cells in a dose-dependent manner. Although a physiological role for leptin is possible, it is suggested that this protein is a mediator of negative rather than positive influential interactions on ovarian function that may compromise fertility.

Association of a common variant of the leptin gene with blood pressure in an obese Brazilian population

BACKGROUND

This study assessed in obese Brazilians subjects whether a common variant of leptin gene, -2548G>A, is associated with blood pressure changes.

METHODS

A total of 140 subjects, 99 women; mean age of 45.2 +/- 12.4 years; body mass index (BMI) = 38.5 +/- 8.0 kg/m2 were included. Blood pressure was recorded using Dinamap 1846 (Critikon, Tampa, FL). Molecular analysis was made by use of PCR and restriction fragment-length polymorphism analysis. Plasma insulin and leptin concentrations were determined by radioimmunoassay.

RESULTS

AA homozygotes, in comparison with the G-allele carriers, showed significant lower levels of systolic, diastolic, and mean arterial pressure (120 +/- 10 vs. 132 +/- 17 mm Hg, P = 0.01; 75 +/- 6 vs. 84 +/- 12 mm Hg, P = 0.009; 92 +/- 7 vs. 100 +/- 12 mm Hg, P = 0.007, respectively). The differences in blood pressure remained significant after adjusting for the influence of gender, age, obesity, and body fat distribution as well as for leptin, insulin, and homeostasis model assessment of insulin resistance. A stepwise regression analysis confirmed that the LEP AA genotype independently predicted blood pressure changes. On the other hand, in GG homozygotes, insulinemia showed a significant association with blood pressure values. This suggests that common LEP genotype carriers exhibiting high insulin levels, reflecting an insulin-resistant state, were particularly prone to higher blood pressure levels.

CONCLUSIONS

Our results showing that higher blood pressure levels were found with the most prevalent -2548G>A genotype, whereas patients with the AA genotype seemed to be protected from hypertension, indicate that the -2548G>A polymorphism of LEP appears to be an important mediator of obesity hypertension.

Leptin receptor Gln223Arg polymorphism and breast cancer risk in Nigerian women: a case control study

Background

Leptin, a 16 kDa polypeptide hormone, implicated in various physiological processes, exerts its action through the leptin receptor, a member of the class I cytokine receptor family. Both leptin and leptin receptor have recently been implicated in processes leading to breast cancer initiation and progression in animal models and humans. An A to G transition mutation in codon 223 in exon 6 of the leptin receptor gene, resulting in glutamine to arginine substitution (Gln223Arg), lies within the first of two putative leptin-binding regions and may be associated with impaired signaling capacity of the leptin receptor. This study was designed to assess the role of this polymorphism in breast cancer susceptibility in Nigerian women.

Methods

We utilized a polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) assay to evaluate the association between the Gln223Arg polymorphism of the leptin receptor gene and breast risk in Nigeria in a case control study involving 209 women with breast cancer and 209 controls without the disease. Study participants were recruited from surgical outpatient clinics and surgical wards of four University Teaching Hospitals located in Midwestern and southeastern Nigeria between September 2002 and April 2004.

Results

Premenopausal women carrying at least one LEPR 223Arg allele were at a modestly increased risk of breast cancer after adjusting for confounders (OR = 1.8, 95% confidence interval [CI] 1.0–3.2, p = 0.07). There was no association with postmenopausal breast cancer risk (OR = 0.9, 95% CI 0.4–1.8, p = 0.68).

Conclusion

Our results suggest that the LEPR Gln223Arg polymorphism in the extracellular domain of the LEPR receptor gene is associated with a modestly increased risk of premenopausal breast cancer in Nigerian women.

Absence of thyrotropin-induced increase in leptin levels in patients with history of differentiated thyroid carcinoma undergoing recombinant human thyrotropin testing

BACKGROUND

Some extra-thyroid effects of TSH have been described in vitro and in vivo. TSH has recently been suggested to induce interleukin-6 secretion by adipocytes. Leptin is the main protein secreted by adipose tissue.

OBJECTIVE

The aim of our study was to evaluate the acute effect of the recombinant human TSH (rhTSH)-induced TSH surge on serum leptin levels in thyroidectomized patients undergoing levothyroxine (L-T4) suppressive therapy for differentiated thyroid carcinoma (DTC).

DESIGN

A cohort of 15 female DTC patients was evaluated. Standard rhTSH testing was performed. Leptin, TSH, thyroid hormones, and thyroglobulin were measured before and 3, 6, and 9 days after rhTSH testing. Some metabolic parameters were also evaluated at the baseline.

RESULTS

Baseline leptin levels were 12.2+/-3.2 microg/l. Only body mass index (BMI) correlated significantly (p<0.05) with leptin levels. After rhTSH administration, TSH levels increased significantly (p<0.001), while thyroid hormones remained unchanged. Twenty hours after the last rhTSH administration, leptin (11.8+/-3.0 microg/l) levels were unchanged. The maximal TSH level was negatively related with BMI (p<0.05), but no correlation between maximal TSH and leptin levels after rhTSH was noted.

CONCLUSIONS

Our in vivo experimental model suggests that an acute TSH increase after rhTSH testing is ineffective in changing circulating leptin levels.

Role of neonatal hyperleptinaemia on serum adiponectin and suppressor of cytokine signalling-3 expression in young rats

Previously we had shown that neonatal leptin treatment programmes for both hyperleptinaemia and hyperinsulinaemia, which lead to leptin resistance and low expression of the hypothalamic leptin receptor (OB-Rb) of rats aged 150 d. Here we investigated in young post-weaned rats (age 30 d) if leptin treatment during lactation induces leptin and insulin resistance and if those changes are accompanied by changes in the suppressor of cytokine signalling-3 (SOCS-3) expression and serum adiponectin concentration. After delivery, the pups were divided into two groups: (1) a leptin group (Lep) that were injected with leptin daily (8 microg/100 g body weight subcutaneously) for the first 10 d of lactation; (2) a control (C) group, receiving saline. After weaning (day 21), body weight was monitored until the animals were age 30 d. They were tested for food intake in response to either leptin (0.5 mg/kg body weight intraperitoneally) (CL, LepL) or saline (CSal, LepSal) when they were aged 30 d. The CL group showed lower food intake, but no response was observed in the LepL group, suggesting leptin resistance. The Lep group had hyperleptinaemia (five-fold), hyperinsulinaemia (+42.5%) and lower levels of serum adiponectin (-43.2%). The hypothalamic expression of OB-Rb was lower (-22%) and SOCS-3 was higher (+52.8%) in the Lep group. We conclude that neonatal leptin treatment programmes for leptin resistance as soon as 30 d and suggests that SOCS-3 appears to be of particular importance in this event. In the Lep group, the lower serum adiponectin levels were accompanied by higher serum insulin, indicating a probable insulin resistance.

Interleukin-6 and leptin as markers of energy metabolic changes in advanced ovarian cancer patients

The progression of the neoplastic disease is characterized by specific alterations of energy metabolism and by symptoms like fatigue, anorexia, nausea, anaemia, immunodepression and poor performance status (PS). The main cause of these symptoms and metabolic abnormalities is the chronic action of proinflammatory cytokines released both by tumour and immune cells. The present study aimed to assess the relationship between markers of inflammation (C-Reactive Protein, Fibrinogen, proinflammatory cytokines) and energy metabolic status (BMI, leptin, oxidative stress) according to clinical parameters in 104 ovarian cancer patients at different stage and, moreover, to evaluate prospectively the changes of these parameters in accordance to tumour response in a subgroup of 70 advanced stage ovarian cancer patients. Advanced stage and poor PS were associated to high-grade inflammation and impaired energy metabolism. Among inflammatory mediators, interleukin (IL)-6 had a central role as predictive factor of leptin, reactive oxygen species and glutathione peroxidase. In turn, leptin considered the key marker of the nutritional status and energy metabolism, was independently determined from stage and IL-6, not only from BMI. Moreover, the evaluation of the changes of these parameters during the course of the neoplastic disease in the subgroup of advanced ovarian cancer patients clearly unveils the central role of IL-6 and leptin as early markers of the metabolic alterations and symptoms associated to disease progression in advanced stage ovarian cancer. Their assessment should be included in monitoring disease outcome, especially when cancer is no longer curable and quality of life becomes the primary endpoint.

Leptin affects endocardial cushion formation by modulating EMT and migration via Akt signaling cascades

Blood circulation is dependent on heart valves to direct blood flow through the heart and great vessels. Valve development relies on epithelial to mesenchymal transition (EMT), a central feature of embryonic development and metastatic cancer. Abnormal EMT and remodeling contribute to the etiology of several congenital heart defects. Leptin and its receptor were detected in the mouse embryonic heart. Using an ex vivo model of cardiac EMT, the inhibition of leptin results in a signal transducer and activator of transcription 3 and Snail/vascular endothelial cadherin-independent decrease in EMT and migration. Our data suggest that an Akt signaling pathway underlies the observed phenotype. Furthermore, loss of leptin phenocopied the functional inhibition of alphavbeta3 integrin receptor and resulted in decreased alphavbeta3 integrin and matrix metalloprotease 2, suggesting that the leptin signaling pathway is involved in adhesion and migration processes. This study adds leptin to the repertoire of factors that mediate EMT and, for the first time, demonstrates a role for the interleukin 6 family in embryonic EMT.

Correlation between expression of leptin and clinicopathological features and prognosis in patients with gastric cancer

BACKGROUND

The relationship between the expression of leptin in the tissue of gastric cancer and the clinicopathological features as well as patients' outcome were investigated.

METHODS

Sixty-one gastric cancer specimens were investigated by immunohistochemical studies with anti-leptin and anti-vascular endothelial growth factor (VEGF) antibodies and by monitoring patients for at least 3 years after surgery.

RESULTS

A positive rate of leptin expression was significantly associated with Borrmann classification (Borrmann type 1 and type 2 68.2% vs Borrmann type 3 and type 4 or unclassified 35.3%), tumor histology (well differentiated tumors 87.5% vs poorly differentiated tumors 48.9%), lymph node metastasis (with 69.0% vs without 36.8%) and stage (stage III + IV 69.0% vs stage I + II 36.8%). There was a significant association between leptin expression and VEGF expression. In the poorly differentiated group, the overall survival rate for patients with a weak expression of leptin (histochemistry score <0.5) was significantly higher than that in patients with a strong expression (histochemistry score =0.5). The Cox proportional hazards model identified serosal involvement, tumor size, metastasis, tumor histology, leptin expression, lymph node metastasis, age and postoperative chemotherapy as significant prognostic factors.

CONCLUSIONS

The expression of leptin in the tissue of gastric cancer was significantly associated with tumor histology, Borrmann classification, lymph node metastasis and stage of gastric cancer. In patients with poorly differentiated gastric cancer, a poor prognosis was found in those with a strong expression of leptin.

Maternal leptin concentrations are similar in African Americans and Caucasians in normal pregnancy, preeclampsia and small-for-gestational-age infants

Leptin concentrations were measured in African American women in order to assess leptin's role in the increased frequency and severity of preeclampsia. In addition, leptin concentrations were measured in women who delivered small-for-gestational-age (SGA) infants. A case-control study of African American and Caucasian women with normal pregnancies, preeclampsia, or SGA infants was done. Plasma leptin was quantitated by radio-immunoassay. The previously recognized pattern of increased leptin concentrations in preeclampsia was replicated. Leptin concentrations did not differ by race in any diagnostic category, and concentrations in women with SGA infants were not higher than those in healthy women. Differences in the frequency and severity of preeclampsia in African Americans cannot be explained by higher leptin concentrations.

Leptin and the regulation of the hypothalamic-pituitary-adrenal axis

Leptin, the product of the obesity gene (ob) predominantly secreted from adipocytes, plays a major role in the negative control of feeding and acts via a specific receptor (Ob-R), six isoforms of which are known at present. Evidence has been accumulated that leptin, like other peptides involved in the central regulation of food intake, controls the function of the hypothalamic-pituitary-adrenal (HPA) axis, acting on both its central and peripheral branches. Leptin, along with Ob-R, is expressed in the hypothalamus and pituitary gland, where it modulates corticotropin-releasing hormone and ACTH secretion, probably acting in an autocrine-paracrine manner. Only Ob-R is expressed in the adrenal gland, thereby making it likely that leptin affects it by acting as a circulating hormone. Although in vitro and in vivo findings could suggest a glucocorticoid secretagogue action in the rat, the bulk of evidence indicates that leptin inhibits steroid-hormone secretion from the adrenal cortex. In keeping with this, leptin was found to dampen the HPA axis response to many kinds of stress. In contrast, leptin enhances catecolamine release from the adrenal medulla. This observation suggests that leptin activates the sympathoadrenal axis and does not appear to agree with its above-mentioned antistress action. Leptin and/or Ob-R are also expressed in pituitary and adrenal tumors, but little is known about the role of this cytokine in the pathophysiology.