Rs4862705 in the melatonin receptor 1A gene is associated with renal function decline in type 1 diabetes individuals.

Aim: The pathogenesis of chronic diabetes complications has oxidative stress as one of the major elements, and single-nucleotide polymorphisms (SNPs) in genes belonging to antioxidant pathways modulate susceptibility to these complications. Considering that melatonin is a powerful antioxidant compound, our aim was to explore, in a longitudinal cohort study of type 1 diabetes (T1D) individuals, the association of microvascular complications and SNPs in the gene encoding melatonin receptor 1A (MTNR1A). Methods: Eight SNPs in MTNR1A were genotyped in 489 T1D individuals. Besides cross-sectional analyses of SNPs with each one of the microvascular complications (distal polyneuropathy, cardiovascular autonomic neuropathy, retinopathy, and diabetic kidney disease), a longitudinal analysis evaluated the associations of SNPs with renal function decline in 411 individuals followed up for a median of 8 years. In a subgroup of participants, the association of complications with urinary 6-sulfatoxymelatonin (aMT6s) concentration was investigated. Results: The group of individuals with a renal function decline ≥ 5 mL min-1 1.73 m-2 year-1 presented a higher frequency of the A allele of rs4862705 in comparison with nondecliners, even after adjustment for confounding variables (OR = 1.84, 95% CI = 1.20-2.82; p = 0.0046). No other significant associations were found. Conclusions: This is the first study showing an association between a variant in a gene belonging to the melatonin system and renal function decline in the diabetic setting.

Variant rs17619600 in the gene encoding serotonin receptor 2B (HTR2B) increases the risk of gestational diabetes mellitus: a case-control study.

BACKGROUND: During pregnancy, the increase in maternal insulin resistance is compensated by hyperplasia and increased function of maternal pancreatic beta cells; the failure of this compensatory mechanism is associated with gestational diabetes mellitus (GDM). Serotonin participates in beta cell adaptation, acting downstream of the prolactin pathway; the blocking of serotonin receptor B (HTR2B) signaling in pregnant mice impaired beta cell expansion and caused glucose intolerance. Thus, given the importance of the serotoninergic system for the adaptation of beta cells to the increased insulin demand during pregnancy, we hypothesized that genetic variants (single nucleotide polymorphisms [SNPs]) in the gene encoding HTR2B could influence the risk of developing GDM. METHODS: This was a case-control study. Five SNPs (rs4973377, rs765458, rs10187149, rs10194776, and s17619600) in HTR2B were genotyped by real-time polymerase chain reaction in 453 women with GDM and in 443 pregnant women without GDM. RESULTS: Only the minor allele C of SNP rs17619600 conferred an increased risk for GDM in the codominant model (odds ratio [OR] 2.15; 95% confidence interval [CI] 1.53-3.09; P < 0.0001) and in the rare dominant model (OR 2.32; CI 1.61-3.37; P < 0.0001). No associations were found between the SNPs and insulin use, maternal weight gain, newborn weight, or the result of postpartum oral glucose tolerance test (OGTT). In the overall population, carriers of the XC genotype (rare dominant model) presented a higher area under the curve (AUC) of plasma glucose during the OGTT, performed for diagnostic purposes, compared with carriers of the TT genotype of rs17619600. CONCLUSIONS: SNP rs17619600 in the HTR2B gene influences glucose homeostasis, probably affecting insulin release, and the presence of the minor allele C was associated with a higher risk of GDM.

Non-Alcoholic Fatty Liver Disease in Long-Term Type 2 Diabetes: Role of rs738409 PNPLA3 and rs499765 FGF21 Polymorphisms and Serum Biomarkers.

Fibroblast growth factor 21 (FGF21) signaling and genetic factors are involved in non-alcoholic fatty liver disease (NAFLD) pathogenesis. However, these factors have rarely been studied in type 2 diabetes mellitus (T2D) patients from admixed populations such as in those of Brazil. Therefore, we aimed to evaluate rs738409 patanin-like phospholipase domain-containing protein (PNPLA3) and rs499765 FGF21 polymorphisms in T2D, and their association with NAFLD, liver fibrosis, and serum biomarkers (FGF21 and cytokeratin 18 levels). A total of 158 patients were included, and the frequency of NAFLD was 88.6%, which was independently associated with elevated body mass index. Significant liver fibrosis (≥F2) was detected by transient elastography (TE) in 26.8% of NAFLD patients, and was independently associated with obesity, low density lipoprotein, and gamma-glutamyl transferase (GGT). PNPLA3 GG genotype and GGT were independently associated with cirrhosis. PNPLA3 GG genotype patients had higher GGT and AST levels; PNPLA3 GG carriers had higher TE values than CG patients, and FGF21 CG genotype patients showed lower gamma-GT values than CC patients. No differences were found in serum values of FGF21 and CK18 in relation to the presence of NAFLD or liver fibrosis. The proportion of NAFLD patients with liver fibrosis was relevant in the present admixed T2D population, and was associated with PNPLA3 polymorphisms.

Association of UCP3 Polymorphisms with Nonalcoholic Steatohepatitis and Metabolic Syndrome in Nonalcoholic Fatty Liver Disease Brazilian Patients.

Background: We investigated the possible association of uncoupling protein 3 gene (UCP3) single nucleotide polymorphisms (SNPs) with nonalcoholic steatohepatitis (NASH) and metabolic syndrome (MetS) in nonalcoholic fatty liver disease (NAFLD) Brazilian patients. Methods:UCP3 SNPs rs1726745, rs3781907, and rs11235972 were genotyped in 158 biopsy-proven NAFLD Brazilian patients. Statistics was performed with JMP, R, and SHEsis softwares. Results: The TT genotype of rs1726745 was associated with less occurrence of MetS (P = 0.006) and with lower body mass index (BMI) in the entire NAFLD sample (P = 0.01) and in the NASH group (P = 0.02). The rs1726745-T was associated with lower values of AST (P = 0.001), ALT (P = 0.0002), triglycerides (P = 0.01), and total cholesterol (P = 0.02) in the entire NAFLD sample. Between groups, there were lower values of aminotransferases strictly in individuals with NASH (AST, P = 0.002; ALT, P = 0.0007) and with MetS (AST, P = 0.002; ALT, P = 0.001). The rs3781907-G was associated with lower GGT elevation values in the entire NAFLD sample (P = 0.002), in the NASH group (P = 0.004), and with MetS group (P = 0.003) and with protection for advanced fibrosis (P = 0.01). The rs11235972-A was associated with lower GGT values in the entire NAFLD sample (P = 0.006) and in the NASH group (P = 0.01) and with MetS group (P = 0.005), with fibrosis absence (P = 0.01) and protection for advanced fibrosis (P = 0.01). The TAA haplotype was protective for NASH (P = 0.002), and TGG haplotype was protective for MetS (P = 0.01). Conclusion:UCP3 gene variants were associated with protection against NASH and MetS, in addition to lower values of liver enzymes, lipid profile, BMI and, lesser fibrosis severity in the studied population.

Alcohol Use Disorder is Associated with Upregulation of MicroRNA-34a and MicroRNA-34c in Hippocampal Postmortem Tissue.

BACKGROUND: To investigate epigenetic mechanisms potentially involved in the cognitive decline associated with chronic alcohol intake, we evaluated the expressions of three micro-RNAs (miR-34a, -34b, and -34c) highly expressed in the hippocampus and involved in neuronal physiology and pathology. MiR-34a participates in functioning and survival of mature neurons; miR-34b is associated with Alzheimer-like disorders; and miR-34c is implicated in the memory impairment of Alzheimer disease in rodents and humans. METHODS: A total of 69 cases were selected from the Biobank for Aging Studies and categorized according to the absence (n = 50) or presence (n = 19) of alcohol use disorder (AUD). Cases presenting with neuropathological diagnoses of dementias were excluded. Total RNA was extracted from hippocampal paraffinized slices, complementary DNA was synthesized from miRs, and RT-qPCR was performed with TaqMan® assays. RESULTS: Higher expressions of miR-34a and miR-34c, but not of miR-34b, were found in the group with AUD in comparison with the group without AUD after adjustment for potential confounders (age, sex, body mass index, presence of hypertension, diabetes mellitus, smoking, and physical inactivity). CONCLUSIONS: Hippocampal upregulation of miR-34a and miR-34c may be involved in the cognitive decline associated with chronic alcohol consumption.

Allelic variations in genes belonging to glutathione system increase proliferative retinopathy risk in type 1 diabetes individuals.

AIMS: Given the participation of oxidative stress in the pathogenesis of diabetic complications, we evaluated, in type 1 diabetes (T1D) individuals, the association between diabetic retinopathy (DR) and functional single nucleotide polymorphisms (SNPs) in regulatory regions of two genes belonging to the antioxidant glutathione (GSH) system: rs17883901 in GCLC and rs713041 in GPX4. METHODS: A cross-sectional case-control study included 288 individuals (61% women, 34[±11] years old, diabetes duration of 22[±9] years, mean [±SD]) sorted according to DR stages: absence of DR (ADR), non-proliferative DR (NPDR) and proliferative DR (PDR). SNPs were genotyped by real-time PCR using fluorescent labelled probes. Logistic regression models with adjustment for confounding covariates were employed. RESULTS: The presence of at least one T-allele of rs17883901 in GCLC was an independent risk factor for PDR (OR 4.13, 95% CI 1.38-13.66, p = 0.014) in a polytomous regression model (PDR versus ADR). The presence of at least one T-allele of rs713041 in GPX4 conferred protection against PDR (OR 0.30, 95% CI 0.11-0.80, p = 0.017) in female T1D individuals. CONCLUSION: The functional SNPs rs17883901 and rs713041 modulate the risk for PDR in the studied population of T1D individuals, widening the spectrum of candidate genes for this complication.

Glutathione peroxidase 4 functional variant rs713041 modulates the risk for cardiovascular autonomic neuropathy in individuals with type 1 diabetes.

Cardiac autonomic neuropathy is a neglected diabetic chronic complication for which genetic predictors are rarely reported. Oxidative stress is implicated in the pathogenesis of microvascular complications, and glutathione peroxidase 4 is involved in the detoxification of peroxides and of reactive oxygen species. Thus, the association of a functional variant in the gene encoding glutathione peroxidase 4 (rs713041) with this diabetic complication was investigated in 341 individuals with type 1 diabetes evaluated for cardiac autonomic neuropathy status (61.7% women, 34 [27-42] years old; diabetes duration: 21 [15-27] years; HbA1c: 8.3% [7.4-9.4]; as median [interquartile interval]). Cardiac autonomic neuropathy was present in 29% of the participants. There was an inverse association of the minor T allele of rs713041 with cardiac autonomic neuropathy (odds ratio = 0.39; 95% confidence interval = 0.17-0.90; p = 0.0271) after adjustment for potential confounders. The functional glutathione peroxidase 4 variant rs713041 modulated the risk for cardiac autonomic neuropathy in the studied population with type 1 diabetes.

Association between the CYBA and NOX4 genes of NADPH oxidase and its relationship with metabolic syndrome in non-alcoholic fatty liver disease in Brazilian population.

BACKGROUND: Oxidative stress has been implicated in the progression of severe forms of non-alcoholic fatty liver disease (NAFLD). NADPH oxidase produces reactive oxygen species. In the present study, we investigated for the first time two single nucleotide polymorphisms (SNPs) in the regulatory region of genes encoding NADPH oxidase 4 (NOX4) and p22phox (CYBA) in NAFLD. METHODS: A total of 207 biopsy-proven NAFLD patients [simple steatosis (n = 27); nonalcoholic steatohepatitis (NASH) (n = 180)] were evaluated. Genomic DNA was extracted from peripheral blood cells, and polymorphisms in CYBA (unregistered) and NOX4 (rs3017887) were determined by direct sequencing of PCR. RESULTS: Associations of CYBA-675 T/A with high-density lipoprotein (HDL) (TT vs TA vs AA; P < 0.01) and triglycerides (TGL) (TT vs XA; P < 0.01) were observed only in NASH patients. For polymorphisms in the NOX4 gene, NOX4 (rs3017887) CA + AA genotypes was significant associated with alanine aminotransferase (ALT) (CA + AA vs CC; P = 0.02). However, there was no association of SNPs in the CYBA and NOX4 genes encoding the NADPH oxidase system proteins and the presence of NASH. Regarding the clinical results, it was observed that the most advanced degrees of fibrosis occurred in patients diagnosed with type 2 diabetes mellitus (66.9% vs 37.5%, P < 0.01) and those who were more obese (32.2 vs 29.0 kg/m2, P < 0.01). In addition, serum glucose and insulin levels increased significantly in the presence of NASH. CONCLUSIONS: There were associations between the presence of the allele A in the NOX4 SNP and a higher concentration of ALT in the NAFLD population; between the presence of the AA genotype in the polymorphism of the CYBA-675 T/A CYBA gene and a higher level of TGL and lower HDL in NASH patients. The presence of metabolic syndrome was associated with advanced degrees of fibrosis in NAFLD patients.

Hormetic modulation of hepatic insulin sensitivity by advanced glycation end products.

Because of the paucity of information regarding metabolic effects of advanced glycation end products (AGEs) on liver, we evaluated effects of AGEs chronic administration in (1) insulin sensitivity; (2) hepatic expression of genes involved in AGEs, glucose and fat metabolism, oxidative stress and inflammation and; (3) hepatic morphology and glycogen content. Rats received intraperitoneally albumin modified (AlbAGE) or not by advanced glycation for 12 weeks. AlbAGE induced whole-body insulin resistance concomitantly with increased hepatic insulin sensitivity, evidenced by activation of AKT, inactivation of GSK3, increased hepatic glycogen content, and decreased expression of gluconeogenesis genes. Additionally there was reduction in hepatic fat content, in expression of lipogenic, pro-inflamatory and pro-oxidative genes and increase in reactive oxygen species and in nuclear expression of NRF2, a transcription factor essential to cytoprotective response. Although considered toxic, AGEs become protective when administered chronically, stimulating AKT signaling, which is involved in cellular defense and insulin sensitivity.

Association of a variant in the regulatory region of NADPH oxidase 4 gene and metabolic syndrome in patients with chronic hepatitis C.

BACKGROUND: Given the important contribution of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system to the generation of reactive oxygen species induced by hepatitis C virus (HCV), we investigated two single nucleotide polymorphisms (SNPs) in the putative regulatory region of the genes encoding NADPH oxidase 4 catalytic subunit (NOX4) and its regulatory subunit p22phox (CYBA) and their relation with metabolic and histological variables in patients with HCV. METHODS: One hundred seventy eight naïve HCV patients (49.3% male; 65% HCV genotype 1) with positive HCV RNA were genotyped using specific primers and fluorescent-labeled probes for SNPs rs3017887 in NOX4 and -675 T → A in CYBA. RESULTS: No association was found between the genotype frequencies of NOX4 and CYBA SNPs and inflammation scores or fibrosis stages in the overall population. The presence of the CA + AA genotypes of the NOX4 SNP was nominally associated with a lower alanine aminotransferase (ALT) concentration in the male population (CA + AA = 72.23 ± 6.34 U/L versus CC = 100.22 ± 9.85; mean ± SEM; P = 0.05). The TT genotype of the CYBA SNP was also nominally associated with a lower ALT concentration in the male population (TT = 84.01 ± 6.77 U/L versus TA + AA = 109.67 ± 18.37 U/L; mean ± SEM; P = 0.047). The minor A-allele of the NOX4 SNP was inversely associated with the frequency of metabolic syndrome (MS) in the male population (odds ratio (OR): 0.15; 95% confidence interval (CI): 0.03 to 0.79; P = 0.025). CONCLUSIONS: The results suggest that the evaluated NOX4 and CYBA SNPs are not direct genetic determinants of fibrosis in HCV patients, but nevertheless NOX4 rs3017887 SNP could indirectly influence fibrosis susceptibility due to its inverse association with MS in male patients.

Hyperinsulinism/hyperammonemia (HI/HA) syndrome due to a mutation in the glutamate dehydrogenase gene / Síndrome de hiperinsulinemia/hiperamonemia devido a uma mutação no gene da glutamato desidrogenase

The hyperinsulinism/hyperammonemia (HI/HA) syndrome is a rare autosomal dominant disease manifested by hypoglycemic symptoms triggered by fasting or high-protein meals, and by elevated serum ammonia. HI/HA is the second most common cause of hyperinsulinemic hypoglycemia of infancy, and it is caused by activating mutations in GLUD1, the gene that encodes mitochondrial enzyme glutamate dehydrogenase (GDH). Biochemical evaluation, as well as direct sequencing of exons and exon-intron boundary regions of the GLUD1 gene, were performed in a 6-year old female patient presenting fasting hypoglycemia and hyperammonemia. The patient was found to be heterozygous for one de novo missense mutation (c.1491A>G; p.Il497Met) previously reported in a Japanese patient. Treatment with diazoxide 100 mg/day promoted complete resolution of the hypoglycemic episodes. Arq Bras Endocrinol Metab. 2012;56(8):485-9.

A síndrome de hiperinsulinemia/hiperamonemia (HI/HA) é uma condição rara, de herança autossômica dominante, que se manifesta por sintomas de hipoglicemia desencadeada por jejum ou refeições de alto conteúdo proteico, juntamente com elevação da concentração de amônia sérica. HI/HA é a segunda causa de hipoglicemia hiperinsulinêmica da infância e é causada por mutações ativadoras no GLUD1, o gene que codifica a enzima mitocondrial glutamato desidrogenase (GDH). A avaliação bioquímica, bem como o sequenciamento direto dos éxons e junções éxon-íntron do gene GLUD1, foi realizada em uma paciente de 6 anos de idade com hipoglicemia de jejum e hiperamonemia. A paciente apresentava uma mutação de novo missense (c.1491A>G; p.Il497Met) em heterozigose, que havia sido previamente relatada em um paciente japonês. O tratamento com diazóxido 100 mg/dia promoveu resolução completa dos episódios hipoglicêmicos. Arq Bras Endocrinol Metab. 2012;56(8):485-9.

Hyperinsulinism/hyperammonemia (HI/HA) syndrome due to a mutation in the glutamate dehydrogenase gene.

The hyperinsulinism/hyperammonemia (HI/HA) syndrome is a rare autosomal dominant disease manifested by hypoglycemic symptoms triggered by fasting or high-protein meals, and by elevated serum ammonia. HI/HA is the second most common cause of hyperinsulinemic hypoglycemia of infancy, and it is caused by activating mutations in GLUD1, the gene that encodes mitochondrial enzyme glutamate dehydrogenase (GDH). Biochemical evaluation, as well as direct sequencing of exons and exon-intron boundary regions of the GLUD1 gene, were performed in a 6-year old female patient presenting fasting hypoglycemia and hyperammonemia. The patient was found to be heterozygous for one de novo missense mutation (c.1491A>G; p.Il497Met) previously reported in a Japanese patient. Treatment with diazoxide 100 mg/day promoted complete resolution of the hypoglycemic episodes.

Association of polymorphisms of glutamate-cystein ligase and microsomal triglyceride transfer protein genes in non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Although the metabolic risk factors for non-alcoholic fatty liver disease (NAFLD) progression have been recognized, the role of genetic susceptibility remains a field to be explored. The aim of this study was to examine the frequency of two polymorphisms in Brazilian patients with biopsy-proven simple steatosis or non-alcoholic steatohepatitis (NASH): -493 G/T in the MTP gene, which codes the protein responsible for transferring triglycerides to nascent apolipoprotein B, and -129 C/T in the GCLC gene, which codes the catalytic subunit of glutamate-cystein ligase in the formation of glutathione. METHODS: One hundred and thirty-one biopsy-proven NAFLD patients (n = 45, simple steatosis; n = 86, NASH) and 141 unrelated healthy volunteers were evaluated. Genomic DNA was extracted from peripheral blood cells, and the -129 C/T polymorphism of the GCLC gene was determined by restriction fragment length polymorphism (RFLP). The -493 G/T polymorphism of the MTP gene was determined by direct sequencing of the polymerase chain reaction products. RESULTS: The presence of at least one T allele in the -129 C/T polymorphism of the GCLC gene was independently associated with NASH (odds ratio 12.14, 95% confidence interval 2.01-73.35; P = 0.007), whereas, the presence of at least one G allele in the -493 G/T polymorphism of the MTP gene differed slightly between biopsy-proven NASH and simple steatosis. CONCLUSION: This difference clearly warrants further investigation in larger samples. These two polymorphisms could represent an additional factor for consideration in evaluating the risk of NAFLD progression. Further studies involving a larger population are necessary to confirm this notion.

Hepatocyte growth factor-regulated tyrosine kinase substrate (HGS) and guanylate kinase 1 (GUK1) are differentially expressed in GH-secreting adenomas.

Pituitary tumors, adenomas in their vast majority, represent around 10-15% of the intracranial neoplasms. Pituitary carcinomas are exceedingly rare. Clinically, these neoplasms cause hormonal dysfunctions, and mass effect symptoms as headache and visual disorders in the case of macroadenomas. Pituitary tumorigenesis is still poorly understood. In order to investigate the expression of cancer-related genes in pituitary tumors, we employed a human cancer cDNA macroarray membrane with 1176 well-characterized human genes related to cancer and tumor biology. We were able to identify several differentially expressed genes, among them hepatocyte growth factor-regulated tyrosine kinase substrate (HGS) and guanylate kinase 1 (GUK1) which were over expressed in a pool of clinically nonfunctioning pituitary adenomas, compared with a spinal cord metastasis of a nonfunctioning pituitary carcinoma. HGS and GUK1 mRNA expression were chosen to be validated by quantitative RT-qPCR, however, only GUK1 had the differential expression confirmed between the adenomas and the metastasis of a pituitary carcinoma. We have also investigated HGS and GUK1 mRNA expressions in a series of 46 pituitary adenomas (18 nonfunctioning, 12 GH-secreting, nine PRL-secreting, and seven ACTH-secreting adenomas). HGS and GUK1 were significantly over expressed in GH-secreting adenomas, compared with ACTH-secreting adenomas and nonfunctioning tumors, and with PRL-secreting adenomas, respectively. We have shown that these genes, involved in tumorigenesis in other tissues, are as well over expressed in the pituitary tumors, however, their role in the oncogenesis of these tumors need to be further investigated.

Studies of the immediate postpartum diabetes remission and/or hypoglycemia after cesarean section in diabetic pregnancy

Five non-diabetic subjects, 5 gestational diabetics (GDM) treated with diet and 4 non-insulin dependent pregestational diabetics (NIDDM) treated with beef-pork insulin during their pregnancy, undergoing elective cesarean section (C-s), were given dextrose infusions without insulin for 7 hours (h) starting lh before the operation. Multiple blood samples were drawn up to 72 h after the C-s. The lowest glucose levels were observed at 3 3 or 6 h after surgery in all but two subjects. Plasma glucose below 2.75 mmol/l (49.5 mg/dl) were observed in 2 NIDDM patients. While in the non-diabetics and GDM the free (total) insulin and C-peptide values fell to very low levels, coinciding with the fall in plasma glucose, in the NIDDM there was a negative correlation between nadir glucose and free insulin levels with the progressive fall of antibody-bound insulin. In 3 out of NIDDM patients the antibodybound insulin fell to 57 to 73 per cent of the preoperative values. IGF-I/SmC, lower in the NIDDM, hGH immunoreactivity and hPL fell after C-s. The results suggest increased glucose utilization insulin-independent in the immediate postpartum in the non-diabetic pregnancy and GDM. However, in the NIDMM, in the presence of significant levels of free insulin, they tend to develop lower plasma glucose levels, sometimes hypoglycemia. Furthermore, lower IGF-I/Smc levels in the NIDDM in comparison to the non-diabetics and GDM would discard their role in the induction of hypoglycemia.