Michal Andel

Genetic evidence that HNF-1α–dependent transcriptional control of HNF-4α is essential for human pancreatic β cell function

Mutations in the genes encoding hepatocyte nuclear factor 4α (HNF-4α) and HNF-1α impair insulin secretion and cause maturity onset diabetes of the young (MODY). HNF-4α is known to be an essential positive regulator of HNF-1α. More recent data demonstrates that HNF-4α expression is dependent on HNF-1α in mouse pancreatic islets and exocrine cells. This effect is mediated by binding of HNF-1α to a tissue-specific promoter (P2) located 45.6 kb upstream from the previously characterized Hnf4α promoter (P1). Here we report that the expression of HNF-4α in human islets and exocrine cells is primarily mediated by the P2 promoter. Furthermore, we describe a G → A mutation in a conserved nucleotide position of the HNF-1α binding site of the P2 promoter, which cosegregates with MODY. The mutation results in decreased affinity for HNF-1α, and consequently in reduced HNF-1α–dependent activation. These findings provide genetic evidence that HNF-1α serves as an upstream regulator of HNF-4α and interacts directly with the P2 promoter in human pancreatic cells. Furthermore, they indicate that this regulation is essential to maintain normal pancreatic function.

Genetic epidemiology of MODY in the Czech republic: new mutations in the MODY genes HNF-4α, GCK and HNF-1α

Aims/hypothesisThe aim of this study was to examine the prevalence and nature of mutations in HNF4α/MODY1, GCK/MODY2 and HNF-1α/MODY3 genes in Czech subjects with clinical diagnosis of MODY.MethodsWe studied 61 unrelated index probands of Czech origin (28 males, 33 females) with a clinical diagnosis of MODY and 202 family members. The mean age of probands was 22.7±12.0 years (range, 6–62) and the mean age at the first recognition of hyperglycaemia was 14.7±6.0 years (range, 1–25). The promotor and coding regions inclusive intron exon boundaries of the HNF-4α, GCK and HNF-1α genes were examined by PCR-dHPLC (HNF-1α and GCK) and direct sequencing.ResultsWe identified 20 different mutations in the HNF-4α, GCK and HNF-1α in 29 families (48% of all families studied), giving a relative prevalence of 5% of MODY1, 31% of MODY2 and 11.5% of MODY3 among the Czech kindred with MODY. Three of 3, 10 of 11 and 1 of 6 of the mutations identified in HNF-4α, GCK and HNF-1α respectively, were new.Conclusion/interpretationOf the families 48% carried mutations in the MODY1–3 genes and of the identified mutations 70% were new. In 52% of Czech families with clinical characteristics of MODY, no mutations were found in the analysed genes. This finding shows that the majority of MODY mutations in a central European population are local and that other MODY genes could be responsible for autosomal dominant transmission of diabetes mellitus.

Relationship between increased body iron stores, oxidative stress and insulin resistance in healthy men.

Aim: The aim of our cross-sectional study was to assess the relationships between body iron stores, oxidative stress, impaired insulin sensitivity and carotid atherosclerosis in a cohort of healthy men in primary prevention of cardiovascular disease. Methods: We examined 151 volunteers, aged 35– 60 years. Anthropometric parameters, markers of metabolic syndrome, insulin resistance, inflammatory markers, parameters of oxidative stress and intima-media thickness of common carotid artery were measured. Results: Ferritin correlated positively with waist circumference, body mass index, impaired insulin sensitivity, plasma triglycerides and inversely with high-density lipoprotein cholesterol. We observed positive correlations between ferritin, oxidized lowdensity lipoprotein and advanced oxidation protein products after adjustment for age, waist circumference, body mass index and measured inflammatory markers (high-sensitivity C-reactive protein, fibrinogen, interleukin-6 and tumor necrosis factor-α). There were no significant associations between ferritin and intima-media thickness or markers of endothelial dysfunction. In a stepwise multiple regression analysis, triglycerides, waist circumference and elevated transaminases were independent determinants of the serum ferritin level. Conclusion: Our results provide evidence for a relationship between plasma ferritin and oxidative modification of lipids as well as proteins in vivo. Higher body iron stores may contribute to impaired insulin sensitivity through increased oxidative stress in a cohort of healthy men.

Gliadin, endomysial and thyroid antibodies in patients with latent autoimmune diabetes of adults (LADA)

Latent autoimmune diabetes of adults (LADA) manifested after the age of 35 is characterized by the presence of disease‐specific autoantibodies (anti‐glutamate decarboxylase GADAb, anti‐IA2Ab). However, autoimmunity in Type 1 diabetes mellitus is not targeted only to pancreatic beta‐cells. No data have so far been published concerning the antibodies associated with other autoimmune disease in LADA patients. The presence of anti‐thyroglobulin (TGAb), anti‐thyroid peroxidase (TPOAb), anti‐gliadin IgA (AGAAb) and IgG (AGGAb) and endomysial antibodies (EMAb) in sera of 68 diabetics typed as LADA was compared with the antibody presence in sera of 85 patients with Type 2 diabetes. We found a significantly higher occurrence of gliadin antibodies in LADA patients: the rate of AGGAb was 19·1% in comparison with 3·5% in the T2DM group (P = 0·0026), the rate of AGAAb was 13·2% in comparison with 3·5% (P = 0·035). The prevalence of EMAb was very low in both groups (1·5% and 0). The two groups differed significantly in the TPOAb rate: 22·1% in LADA compared to 9·4% in T2DM (P = 0·04), whereas no significant difference was found in the presence of TGAb (8·8% and 3·5%, P = 0·187). In comparison with T2DM patients, LADA patients were found to express higher antibody activity against gluten‐related antigens and against TPO.

A comparison of the influence of a high-fat diet enriched in monounsaturated fatty acids and conventional diet on weight loss and metabolic parameters in obese non-diabetic and Type 2 diabetic patients

Aims  The aim of our study was to compare the influence of a hypocaloric, high‐fat diet enriched with MUFA (M) and conventional diet (C) on weight loss and metabolic parameters in obese non‐diabetic and obese Type 2 diabetic subjects over a 3‐month period. It was our hypothesis that the enriched diet would be more effective in decreasing blood glucose and glycated haemoglobin (HbA1c) than the control diet.

A multinational, multi-centre, observational, cross-sectional survey assessing diabetes secondary care in Central and Eastern Europe (DEPAC Survey)

Aims  The objective of this study was to assess diabetes care in outpatient diabetes clinics in the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia.

Iron stores are associated with asymptomatic atherosclerosis in healthy men of primary prevention.

Eur J Clin Invest 2011; 41 (8): 846–853

Nutritional consequences of renal transplantation.

Successful kidney transplantation leads to restoration of renal function. Some metabolic disorders from chronic renal failure may persist and new metabolic abnormalities can develop (obesity, diabetes, hypertension, bone disease, and anemia). Additionally, influence of immunosuppressive drugs (corticosteroids, cyclosporine A, tacrolimus, and rapamycin) may aggravate the course of diabetes, hypertension, and dyslipidemia. Nutritional management of renal transplantation is divided into the pretransplant period, transplant surgery, and early and late posttransplant period. Patients in the pretransplant period in dialysis treatment may develop protein-energy malnutrition and negative nitrogen balance, with loss of lean body mass and fat deposits. Nutritional management in the early posttransplant period with a functioning kidney graft necessitates fluid and electrolyte balance control with protein intake of 1,2/kg BW/day and 30-35 kcal/kg BW/day. In a nonfunctioning kidney graft, dialysis treatment continues and the therapeutic dose of immunosuppressive drugs must be reduced. The principal objective in the late posttransplant period is the maintenance of optimal nutritional status. Nutrition is important in managing obesity, insulin resistance, diabetes, hyperlipidemia, and hypertension. Other posttransplant conditions for which diet and/or nutritional supplements may be beneficial include hypomagnesemia, hypophosphatemia, hyperuricemia, hyperkalemia, hyperhomocysteinemia, chronic renal allograft failure, renal anemia, and renal bone disease.

HLA DRB1, DQB1 and insulin promoter VNTR polymorphisms: interactions and the association with adult‐onset diabetes mellitus in Czech patients

Both the human leucocyte antigen (HLA) DRB1 and the HLA DQB1 gene loci play a role in the development and progression of autoimmune diabetes mellitus (T1DM). Similarly, the insulin promoter variable number tandem repeats (INS‐VNTR) polymorphism is also involved in the pathogenesis of diabetes mellitus (DM). We studied the association between each of these polymorphisms and DM diagnosed in patients older than age 35 years. Furthermore, we analysed possible interactions between HLA DRB1/DQB1 and INS‐VNTR polymorphisms. Based on C‐peptide and GADA levels we were able to distinguish three types of diabetes: T1DM, latent autoimmune diabetes in adults (LADA) and T2DM. INS‐VNTR was genotyped indirectly by typing INS–23HphI A/T polymorphism. The genotype and allele frequencies of INS–23HphI did not differ between each of the diabetic groups and group of healthy subjects. We did, however, observe an association between the INS–23HphI alleles, genotypes and C‐peptide secretion in all diabetic patients: A allele frequency was 86.2% in the C‐peptide‐negative group vs. 65.4% in the C‐peptide‐positive group (Pcorr. < 0.005); AA genotype was found to be 72.4% in the C‐peptide‐negative group vs. 42.6% in the C‐peptide‐positive groups (Pcorr. < 0.01). The HLA genotyping revealed a significantly higher frequency of HLA DRB1*03 allele in both T1DM and LADA groups when compared to healthy subjects: T1DM (25.7%) vs. control group (10.15%), odds ratio (OR) = 3.06, P < 0.05; LADA (27.6%) vs. control (10.15%), OR = 3.37, P < 0.01. The simultaneous presence of both HLA DRB1*04 and INS–23HphI AA genotype was detected in 37.5% of the T1DM group compared to only 9.2% of the healthy individuals group (OR = 5.9, Pcorr. < 0.007). We summarize that in the Central Bohemian population of the Czech Republic, the INS–23HphI A allele appears to be associated with a decrease in pancreatic beta cell secretory activity. HLA genotyping points to at least a partial difference in mechanism, which leads to T1DM and LADA development as well as a more diverse genetic predisposition in juvenile‐ and adult‐onset diabetes. The simultaneous effect of HLA and INS‐VNTR alleles/genotypes predispose individuals to an increased risk of diabetes development.

Association of MHC class I chain related gene-A microsatellite polymorphism with the susceptibility to T1DM and LADA in Czech adult patients.

The results in this study suggest that microsatellite polymorphism within the transmembrane region of MIC‐A gene is associated with genetic susceptibility to adult‐onset of type 1 diabetes mellitus (T1DM), MIC‐A5.1 allele, corrected P = 0.001, whereas it is not associated with latent autoimmune diabetes in adults (LADA) in Czech population. According to our findings, we can hypothesize that adult‐onset T1DM and LADA may have partly different immunogenetic aetiopathogenesis.