Bogda Skowrońska

Insulin: Its role in the central control of reproduction☆

Insulin has long been recognized as a key regulator of energy homeostasis via its actions at the level of the brain, but in addition, plays a role in regulating neural control of reproduction. In this review, we consider and compare evidence from animal models demonstrating a role for insulin for physiological control of reproduction by effects on GnRH/LH secretion. We also review the role that insulin plays in prenatal programming of adult reproduction, and consider specific candidate neurons in the adult hypothalamus by which insulin may act to regulate reproductive function. Finally, we review clinical evidence of the role that insulin may play in adult human fertility and reproductive disorders. Overall, while insulin appears to have a significant impact on reproductive neuroendocrine function, there are many unanswered questions regarding its precise sites and mechanisms of action, and their impact on developing and adult reproductive neuroendocrine function.

Common polymorphism (81Val>Ile) and rare mutations (257Arg>Ser and 335Ile>Ser) of the MC3R gene in obese Polish children and adolescents

The predisposing role to human obesity of the MC3R gene polymorphism is controversial. In this report we present the first study focused on the search for the MC3R polymorphism in the Polish population. Altogether 257 obese children and adolescents (RBMI>120) and 94 adults, who were never obese or overweight (BMI<25), were studied. For all subjects the entire coding sequence was analyzed by direct DNA sequencing. One common polymorphism (81Val>Ile) and two rare mutations (257Arg>Ser and 335Ile>Ser) were identified. The common polymorphism was widely distributed in the obese and control cohorts, while the mutations were identified in four obese subjects only. In case of the 335Ile>Ser substitution a three-generation family, consisting of 20 members, was also analyzed. It was found that all carriers of the 335Ser mutation were obese, but among non-carriers obese subjects also were found. Our study suggests that the predisposing effect to obesity of the 81Ile polymorphic variant is rather unlikely. With regard to the studied rare mutations we suggest that the 335Ser allele may have a small predisposing effect.

Cumulative effect of IFIH1 variants and increased gene expression associated with type 1 diabetes

AIMS IFIH1 (Interferon Induced with Helicase C domain 1) gene encodes a sensor of double-stranded RNA, which initiates antiviral activity. Recent studies have indicated the association of rare and common IFIH1 variants with type 1 diabetes mellitus (T1D). The aim of this study was to investigate whether polymorphisms in the IFIH1 locus are a risk factor for T1D in Caucasian patients from Poland. METHODS We genotyped 514 T1D patients and 713 healthy control individuals for rs3747517, rs1990760, rs2111485 and rs13422767 variants. Cumulative genetic risk score (CGRS) was calculated using unweighted and weighted approaches. We also examined the expression of IFIH1 gene in a cohort of 90 T1D patients. RESULTS All studied polymorphisms showed significant association with type 1 diabetes. The risk alleles G of rs3747517, rs2111485, rs13422767 and A of rs1990760 were observed more frequently in T1D group with P values and allelic odds ratio OR (95%CI) < 0.0001, 1.742 (1.428-2.126); 0.001, 1.336 (1.125-1.588); < 0.0001, 1.799 (1.416-2.285); 0.0005, 1.359 (1.144-1.616), respectively. The risk for type 1 diabetes increased with the growing number of the risk alleles. OR (95%CI) for carriers of ≥ 6 risk alleles reached 2.387 (1.552-3.670) for unweighted CGRS and 3.132 (1.928-5.089) for weighted CGRS. Furthermore, IFIH1 gene expression levels in unstimulated peripheral blood mononuclear cells of T1D patients were significantly higher compared to healthy individuals (mean ± SEM mRNA copy number 163.8 ± 15.7 vs. 117.8 ± 7.2; P = 0.046). CONCLUSIONS This study confirms the association of the IFIH1 locus with susceptibility to T1D in the Polish population. The cumulative effect of rs3747517, rs1990760, rs2111485 and rs13422767 variants on type 1 diabetes risk was observed.

FKBP5 polymorphism is associated with insulin resistance in children and adolescents with obesity

OBJECTIVE Since metabolic syndrome shares several clinical features with hypercortisolism, it was hypothesised that genes altering individual glucocorticoid (GC) sensitivity might be implicated in pathogenesis of obesity and its adverse outcomes. FKBP5 gene encodes a chaperon protein in the GC receptor (GR) complex, which modulates steroid action upon target genes. Its functional variant, rs1360780, may enhance FKBP5 gene transcription, affect GR signalling and thereby influence the hypothalamo-pituitary-adrenal axis. We investigated the association of rs1360780 with obesity and metabolic characteristics in 250 obese children and adolescents (mean age 12.3±3.6years, BMI ≥95th percentile). METHODS Anthropometric measurements, body composition, biochemical and hormonal results were analysed. Genotyping of rs1360780 was compared with 568 lean controls. RESULTS Impaired fasting glucose was present in 8.8%, glucose intolerance in 10.4%, diabetes in 2.8% and dyslipidemia in 28.8% obese individuals. Hypertension was diagnosed in 34 out of 143 patients. No difference was found in FKBP5 polymorphism distribution between subjects with obesity and controls (p>0.05). Stratification by rs1360780 revealed no differences in body mass and composition. However, carriers of the minor allele displayed enhanced insulin resistance (p=0.009) and elevated serum triglyceride (p=0.006), whereas cholesterol, HbA1c, and oral glucose challenge results were similar for all genotypes. Morning ACTH and cortisol did not differ but evening cortisol was higher in minor allele carriers (p=0.039), although this association was lost in logistic regression analysis. CONCLUSION This study does not support the association of FKBP5 with obesity but demonstrates plausible implication of its variant in susceptibility to obesity-related insulin resistance and hypertriglyceridemia.

Neutrophil gelatinase-associated lipocalin and Cathepsin L as early predictors of kidney dysfunction in children with type 1 diabetes

INTRODUCTION The aim of this study was to evaluate serum levels and urinary excretion of neutrophil-gelatinase associated lipocalin (respectively sNGAL and uNGAL) and urinary excretion of Cathepsin L (uCathL) in children with type 1 diabetes mellitus (DM1) who presented normoalbuminuria and the estimated glomerular filtration rate (eGFR) above 90 mL/min/1.73 m2. MATERIAL AND METHODS The study group consisted of 63 children with a diabetes duration of 5.16 ± 3.39 years. The degree of albuminuria was based on urine albumin-to-creatinine ratio (ACR), while eGFR was based on serum cystatin C. Glomerular hyperfiltration (GH) was defined as an eGFR value above 135 mL/min/1.73 m2. RESULTS Children with DM1 showed significantly higher concentrations of uNGAL, and lower sNGAL and uCathL. Significant changes of uNGAL and uCathL levels were even found in children without GH and with optimal glycaemic control (HbA1c < 7.5%). Positive correlations between uNGAL, ACR and eGFR were shown, as well as between uCathL and eGFR. CONCLUSIONS Significant changes in the concentration of markers of early kidney injury: sNGAL, uNGAL, and uCathL, can occur in children with DM1 and normoalbuminuria. The changes of uNGAL and uCathL can be even found in children without GH and with optimal glycaemic control. The earliest signs of diabetic kidney dysfunction seem to result from tubular damage.

Serum leptin and adiponectin levels in children with type 1 diabetes mellitus – Relation to body fat mass and disease course

PURPOSE Leptin and adiponectin are adipokines presenting a wide range of impacts, including glycemic balance regulations. Insulin is one of the main regulators of adipose tissue function. In type 1 diabetes mellitus (T1DM) endogenous insulin secretion is replaced by the exogenous supply, which is not regulated naturally. The aim of the study was to establish serum leptin and adiponectin levels, and their relations to body fat mass and disease course in children with T1DM. MATERIAL/METHODS The study included 75 children with T1DM and the control group of 20 healthy coevals. All children had estimated serum leptin and adiponectin concentrations, lipid profile, and bioelectrical impedance analysis. RESULTS Serum leptin concentrations in children with T1DM were not significantly different from the control group (p=0.067, mean values±SD: 3.11±2.98 vs. 5.29±5.06μg/l, respectively), and related positively to body fat mass in both groups. Adiponectin serum concentrations were significantly higher in children with T1DM than in the control group (p<0.001; mean values: 18.82±9.31 vs. 12.10±5.53μg/ml, respectively), and were not related to the body fat content in the study group. Both, leptin and adiponectin, showed no relation to any of the analyzed parameters of the disease course. CONCLUSIONS Differences observed between children with T1DM and their healthy coevals, when similar in terms of age, body weight, and body fat mass, seem not to depend directly on the disease duration, its metabolic control or insulin supply.

Serum resistin concentrations in children with type 1 diabetes mellitus — negative relation to body fat mass

INTRODUCTION Insulin is one of the major factors regulating adipose tissue function. On the other hand, adipocytes secrete adipocytokines that may influence insulin synthesis and action, and are involved in blood glucose regulation. In type 1 diabetes mellitus (t1DM), beta cells function is replaced with exogenous insulin therapy. This raises a question concerning the impact of t1DM on adipose tissue secretory function. The aim of this study was to evaluate one of the adipocytokines, resistin, serum concentrations in relation to body fat mass in children with t1DM. MATERIAL AND METHODS The study comprised 75 children with t1DM and a control group of 20 healthy coevals. All children had estimated serum resistin concentrations, glycated haemoglobin levels, growth and body weight measurements, and bioelectrical impedance analysis in order to establish body composition. RESULTS Resistin serum concentrations were significantly lower in children with t1DM vs. controls (median values: 343 vs. 590 pg/mL; mean values ± SD: 577 ± 561 vs. 861 ± 628 pg/mL; p < 0.001), and they negatively correlated with body fat mass (p = 0.022) and age (p = 0.022) in the t1DM group, but not in the control group. Disease duration, glycated haemoglobin levels and insulin dosage revealed no direct statistical relation to resistin levels. CONCLUSIONS Diminished serum resistin concentrations and a negative correlation between resistin levels and body fat mass in children with type 1 diabetes seem to result from broken physiological adipo-insular regulations, independent of disease duration, its metabolic control and insulin supply.

Overexpression of miR-652-5p in new onset type 1 diabetes

Introduction. MicroRNAs (miRNAs) are small noncoding RNA regulating gene expression at the posttranscriptional level. miRNAs have emerged as an important regulators of central and peripheral immune tolerance, therefore study the RNA molecules in the context of type 1 diabetes (T1D) pathogenesis is an important issue. The aim of this study was to investigate miR-652-5p expression level in the new onset T1D and an impact on ADAR and MARCH5, potential target genes. Material and methods. The miR-652-5p expression was investigated in the peripheral blood mononuclear cell of newly diagnosed T1D pediatric patients (n = 28) and age-matched controls (n = 28) by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). miRNA targets were analyzed by luciferase reporter assays. Results. Expression analysis revealed upregulation of miR-652-5p in T1D group compared to non-diabetic controls (p Conclusion. Our study revealed miR-652-5p as potential marker of new onset type 1 diabetes.

Erratum to: Normal-range albuminuria does not exclude nephropathy in diabetic children

Erratum to: Pediatr NephrolDOI 10.1007/s00467-010-1443-zIt has come to our attention that the reported NGAL levelsare 10-fold higher than those reported by other researchers.This is best seen from the normal values reported inTable 1. Inaccurate data is due to a decimal mistake. Allreported serum and urine values for NGAL have to bedivided by 10.