Kátia Gonçalves dos Santos

Functional Vascular Endothelial Growth Factor −634G>C SNP Is Associated With Proliferative Diabetic Retinopathy A case-control study in a Brazilian population of European ancestry

OBJECTIVE—The purpose of this study was to evaluate the effect of the single nucleotide polymorphism (SNP) −634G>C at the 5′ regulatory region of the vascular endothelial growth factor (VEGF) in the risk of proliferative diabetic retinopathy (PDR) in the Brazilian population of European ancestry with type 2 diabetes. RESEARCH DESIGN AND METHODS—A case-control study was conducted in 501 type 2 diabetic patients of European ancestry. Patients underwent a standardized clinical, ophthalmological, and laboratory evaluation. Of these, 167 patients had PDR (case patients), and 334 were considered as control subjects (patients without PDR) for PDR. A reference population (110 individuals of European ancestry) was also evaluated. RESULTS—No evidence of association between −634G>C/VEGF and the presence of diabetic retinopathy or type 2 diabetes was observed (P > 0.05). However, CC homozygous for the SNP −634G>C was significantly more frequent in patients with PDR (37 of 167; 22.2%) than in the corresponding control group (40 of 334; 12%) in accordance with a recessive model (P = 0.003). This effect was further observed when creatinine, BMI, sex, duration of type 2 diabetes, HDL cholesterol, and systolic blood pressure were taken into account (odds ratio 1.9 [95% CI 1.01–3.79], P = 0.04). CONCLUSIONS—The presence of the allele −634C/VEGF in homozygosity is an independent risk factor for the development of PDR in type 2 diabetic patients of European ancestry.

An analysis of the global expression of microRNAs in an experimental model of physiological left ventricular hypertrophy.

Background MicroRNAs (miRs) are a class of small non-coding RNAs that regulate gene expression. Studies of transgenic mouse models have indicated that deregulation of a single miR can induce pathological cardiac hypertrophy and cardiac failure. The roles of miRs in the genesis of physiological left ventricular hypertrophy (LVH), however, are not well understood. Objective To evaluate the global miR expression in an experimental model of exercise-induced LVH. Methods Male Balb/c mice were divided into sedentary (SED) and exercise (EXE) groups. Voluntary exercise was performed on an odometer-monitored metal wheels for 35 days. Various tests were performed after 7 and 35 days of training, including a transthoracic echocardiography, a maximal exercise test, a miR microarray (miRBase v.16) and qRT-PCR analysis. Results The ratio between the left ventricular weight and body weight was increased by 7% in the EXE group at day 7 (p<0.01) and by 11% at day 35 of training (p<0.001). After 7 days of training, the microarray identified 35 miRs that were differentially expressed between the two groups: 20 were up-regulated and 15 were down-regulated in the EXE group compared with the SED group (pu200a=u200a0.01). At day 35 of training, 25 miRs were differentially expressed: 15 were up-regulated and 10 were decreased in the EXE animals compared with the SED animals (p<0.01). The qRT-PCR analysis demonstrated an increase in miR-150 levels after 35 days and a decrease in miR-26b, miR-27a and miR-143 after 7 days of voluntary exercise. Conclusions We have identified new miRs that can modulate physiological cardiac hypertrophy, particularly miR-26b, -150, -27a and -143. Our data also indicate that previously established regulatory gene pathways involved in pathological LVH are not changed in physiological LVH.

Polymorphisms of the UCP2 gene are associated with proliferative diabetic retinopathy in patients with diabetes mellitus

Background and objectiveu2002 Uncoupling protein 2 (UCP2) plays a role in controlling reactive oxygen species (ROS) production by mitochondria. As ROS overproduction is related to diabetic retinopathy (DR), UCP2 gene polymorphisms might be involved in the development of this complication. We investigated whether the −866G/A (rs659366), Ala55Val (rs660339) and 45u2003bp insertion/deletion (Ins/Del) polymorphisms in the UCP2 gene might be associated with proliferative DR (PDR).

Relationship of endothelial nitric oxide synthase (eNOS) gene polymorphisms with diabetic retinopathy in Caucasians with type 2 diabetes.

Background: Nitric oxide synthesized by endothelial nitric oxide synthase (eNOS) plays a key role in the regulation of endothelial function, and controversial results regarding the association of eNOS gene polymorphisms with diabetic complications have been reported. Materials and Methods: In this case-control study, the relationship of the −786T/C, the VNTR intron 4 a/b and the 894G/T (Glu298Asp) polymorphisms in the eNOS gene with the presence or severity of diabetic retinopathy was analyzed in 630 Caucasian-Brazilians with type 2 diabetes (434 with and 196 without diabetic retinopathy). Genotyping of eNOS polymorphisms was carried out using the PCR or PCR-RFLP method, and haplotype frequencies were estimated using a Bayesian method. Results: Genotype and allele frequencies in patients with any degree of diabetic retinopathy or proliferative diabetic retinopathy were not significantly different from those of patients without this complication for all eNOS polymorphisms. Likewise, there were no differences in haplotype frequencies among diabetic patients with or without diabetic retinopathy (p values > 0.05 for all comparisons). Conclusion: Our findings do not support the hypothesis that the −786T/C, the VNTR intron 4 a/b and the 894G/T (Glu298Asp) polymorphisms in the eNOS gene play a role in the pathogenesis of diabetic retinopathy in type 2 diabetes.

Endothelial nitric oxide synthase gene polymorphisms and risk of diabetic nephropathy: a systematic review and meta-analysis

BackgroundNitric oxide (NO) has numerous functions in the kidney, including control of renal and glomerular hemodynamics, by interfering at multiple pathological and physiologically critical steps of nephron function. Endothelial NOS (eNOS) gene has been considered a potential candidate gene to diabetic nephropathy (DN) susceptibility. Endothelial nitric oxide synthase gene (eNOS-3) polymorphisms have been associated with DN, however some studies do not confirm this association. The analyzed polymorphisms were 4b/4a, T-786C, and G986T.MethodsThe Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement was used in this report. Case–control studies that had diabetic patients with DN as cases and diabetic patients without nephropathy as controls, as well as that evaluated at least one of the three polymorphisms of interest were considered eligible. All studies published up until December 31st, 2012 were identified by searching electronic databases. Hardy-Weinberg equilibrium assessment was performed. Gene-disease association was measured using odds ratio estimation based on the following genetic contrast/models: (1) allele contrast; (2) additive model; (3) recessive model; (4) dominant model and (4) co-dominant model.ResultsTwenty-two studies were eligible for meta-analysis (4b/a: 15 studies, T-786C: 5 studies, and G984T: 12 studies). Considering 4b/a polymorphism, an association with DN was observed for all genetic models: allele contrast (OR = 1.14, CI: 1.04-1.25); additive (OR = 1.77, CI: 1.37-2.28); recessive (OR = 1.77, CI: 1.38-2,27); dominant (OR = 1.12, CI: 1.01-1.24), with the exception for co-dominance model. As well, T-786C polymorphism showed association with all models, with exception for co-dominance model: allele contrast (OR = 1.22, CI: 1.07-1.39), additive (OR = 1.52, CI: 1.18-1.97), recessive (OR = 1.50, CI: 1.16-1.93), and dominant (OR = 1.11, CI: 1.01-1.23). For the G894T polymorphism, an association with DN was observed in allelic contrast (OR = 1.12, CI: 1.03-1.25) and co-dominance models (OR = 1.13, CI: 1.04-1.37).ConclusionsIn the present study, there was association of DN with eNOS 4b/a and T-786C polymorphism, which held in all genetic models tested, except for co-dominance model. G894T polymorphism was associated with DN only in allele contrast and in co-dominance model. This data suggested that the eNOS gene could play a role in the development of DN.

Association of eNOS gene polymorphisms with renal disease in Caucasians with type 2 diabetes

AIMnIn this study we investigated if the -786T>C, the VNTR intron 4 a/b and the 894G>T (Glu298Asp) polymorphisms in the eNOS gene were associated with renal disease in 617 type 2 diabetic Caucasian-Brazilians. These polymorphisms were also examined in 100 Caucasian healthy blood donors.nnnMETHODSnGenotyping of eNOS polymorphisms was performed by PCR or PCR-RFLP and haplotype frequencies were estimated using a Bayesian method. Logistic regression analysis was done to test for association of eNOS polymorphisms with susceptibility to renal involvement (microalbuminuria, macroalbuminuria or end-stage renal disease). This analysis was carried out assuming three different genetic models for the minor allele, adjusting for possible effect modifiers.nnnRESULTSnGenotype and allele frequencies in patients with renal disease were not significantly different from those of patients with normoalbuminuria and healthy blood donors for all eNOS polymorphisms. Likewise, there were no differences in haplotype frequencies among healthy blood donors and type 2 diabetic patients with or without renal involvement (P>0.05 for all comparisons).nnnCONCLUSIONnNo associations between the -786T>C, the VNTR intron 4 a/b and the 894G>T (Glu298Asp) polymorphisms in the eNOS gene and renal disease were observed in type 2 diabetic Caucasian-Brazilians.

The −308G>A Polymorphism of the TNF Gene Is Associated With Proliferative Diabetic Retinopathy in Caucasian Brazilians With Type 2 Diabetes

PURPOSEnWe tested the hypothesis that tumor necrosis factor (TNF) gene polymorphisms are associated with diabetic retinopathy (DR) in Caucasians with type 2 diabetes mellitus.nnnMETHODSnIn a case-control study, the -238G>A (rs361525), -308G>A (rs1800629), and -857C>T (rs1799724) polymorphisms of the TNF gene were genotyped in 745 outpatients with type 2 diabetes, including 331 subjects without DR, 246 with nonproliferative DR (NPDR), and 168 with proliferative DR (PDR).nnnRESULTSnGenotype and allele frequencies of the -238G>A, -308G>A, and -857C>T polymorphisms in subjects with NPDR were not significantly different from those of subjects without DR (P > 0.05 for all comparisons). However, the A allele of the -308G>A polymorphism was more frequent in subjects with PDR than in those with no DR (18.1% vs. 11.5%, corrected P = 0.035). Multivariate logistic regression analysis showed that the -308A allele was independently associated with an increased risk of PDR, under a dominant model (adjusted odds ratio [aOR], 1.82; 95% confidence interval [CI], 1.11-2.98). The combined analysis of the three polymorphisms also showed that haplotypes containing the -308A allele were associated with an increased risk of PDR (aOR, 2.36; 95% CI, 1.29-4.32).nnnCONCLUSIONSnThis study detected, for the first time to our knowledge, an independent association of the -308G>A polymorphism in the TNF gene with PDR in Caucasian Brazilians with type 2 diabetes. This finding suggests that TNF is a potential susceptibility gene for PDR.

Association study of sorbitol dehydrogenase −888G>C polymorphism with type 2 diabetic retinopathy in Caucasian-Brazilians

Diabetic retinopathy (DR) is a common chronic complication of diabetes and remains the leading cause of blindness in working-aged people. Hyperglycemia increases glucose flux through the polyol pathway, in which aldose reductase converts glucose into intracellular sorbitol, which is subsequently converted to fructose by sorbitol dehydrogenase (SDH). The accelerated polyol pathway triggers a cascade of events leading to retinal vascular endothelial dysfunction and the eventual development of DR. Polymorphisms in the gene encoding aldose reductase have been consistently associated with DR. However, only two studies have analyzed the relationship between polymorphisms in the gene encoding SDH (SORD) and DR. In this case-control study, we investigated whether the -888Gxa0>xa0C polymorphism (rs3759890) in the SORD gene is associated with the presence or severity of DR in 446 Caucasian-Brazilians with type 2 diabetes (241 subjects with and 205 subjects without DR). The -888Gxa0>xa0C polymorphism was also examined in 105 healthy Caucasian blood donors, and the genotyping of this polymorphism was carried out by real-time PCR. The genotype and allele frequencies of the -888Gxa0>xa0C polymorphism in patients with type 2 diabetes were similar to those of blood donors (G allele frequencyxa0=xa00.16 in both groups of subjects). Similarly, the genotype and allele frequencies in patients with DR or the proliferative form of DR were similar to those of patients without this complication (Pxa0>xa00.05 for all comparisons). Thus, our findings suggest that the -888Gxa0>xa0C polymorphism in the SORD gene is not involved in the pathogenesis of DR in type 2 diabetes.

Matrix Metalloproteinase-2 Polymorphisms in Chronic Heart Failure: Relationship with Susceptibility and Long-Term Survival

Circulating levels of matrix metalloproteinase-2 (MMP-2) predict mortality and hospital admission in heart failure (HF) patients. However, the role of MMP-2 gene polymorphisms in the susceptibility and prognosis of HF remains elusive. In this study, 308 HF outpatients (216 Caucasian- and 92 African-Brazilians) and 333 healthy subjects (256 Caucasian- and 77 African-Brazilians) were genotyped for the -1575G>A (rs243866), -1059G>A (rs17859821), and -790G>T (rs243864) polymorphisms in the MMP-2 gene. Polymorphisms were analyzed individually and in combination (haplotype), and positive associations were adjusted for clinical covariates. Although allele frequencies were similar in HF patients and controls in both ethnic groups, homozygotes for the minor alleles were not found among African-Brazilian patients. After a median follow-up of 5.3 years, 124 patients (40.3%) died (54.8% of them for HF). In Caucasian-Brazilians, the TT genotype of the -790G>T polymorphism was associated with a decreased risk of HF-related death as compared with GT genotype (hazard ratio [HR] = 0.512, 95% confidence interval [CI] 0.285–0.920). However, this association was lost after adjusting for clinical covariates (HR = 0.703, 95% CI 0.365–1.353). Haplotype analysis revealed similar findings, as patients homozygous for the -1575G/-1059G/-790T haplotype had a lower rate of HF-related death than those with any other haplotype combination (12.9% versus 28.5%, respectively; P = 0.010). Again, this association did not remain after adjusting for clinical covariates (HR = 0.521, 95% CI 0.248–1.093). Our study does not exclude the possibility that polymorphisms in MMP-2 gene, particularly the -790G>T polymorphism, might be related to HF prognosis. However, due to the limitations of the study, our findings need to be confirmed in further larger studies.

Nitric oxide in the pathophysiology of retinopathy: evidences from preclinical and clinical researches

Retinopathy is the leading cause of blindness and visual disability in working‐aged people. The pathogenesis of retinopathy is an actual and still open query. Alterations contributing to oxidative and nitrosative stress, including elevated nitric oxide and superoxide production, changes in the expression of different isoforms of nitric oxide synthase or endogenous antioxidant system, have been implicated in the mechanisms how this ocular disease develops. In addition, it was documented that renin–angiotensin system has been implicated in the progression of retinopathy. Based on comprehensive preclinical and clinical researches in this area, the role of above‐mentioned factors in the pathogenesis of diabetic retinopathy, hypertensive retinopathy and ischaemic proliferative retinopathy is reviewed in this study. Moreover, the genetic susceptibility factors involved in the development of the retinopathy and possible strategies that utilize antioxidants as additive therapy are also highlighted here.