Integrated bioinformatics approach reveals methylation-regulated differentially expressed genes in obesity

ABSTRACT Objective: To identify DNA methylation and gene expression profiles involved in obesity by implementing an integrated bioinformatics approach. Materials and methods: Gene expression (GSE94752, GSE55200, and GSE48964) and DNA methylation (GSE67024 and GSE111632) datasets were obtained from the GEO database. Differentially expressed genes (DEGs) and differentially methylated genes (DMGs) in subcutaneous adipose tissue of patients with obesity were identified using GEO2R. Methylation-regulated DEGs (MeDEGs) were identified by overlapping DEGs and DMGs. The protein-protein interaction (PPI) network was constructed with the STRING database and analyzed using Cytoscape. Functional modules and hub-bottleneck genes were identified by using MCODE and CytoHubba plugins. Functional enrichment analyses were performed based on Gene Ontology terms and KEGG pathways. To prioritize and identify candidate genes for obesity, MeDEGs were compared with obesity-related genes available at the DisGeNET database. Results: A total of 54 MeDEGs were identified after overlapping the lists of significant 274 DEGs and 11,556 DMGs. Of these, 25 were hypermethylated-low expression genes and 29 were hypomethylated-high expression genes. The PPI network showed three hub-bottleneck genes (PTGS2, TNFAIP3, and FBXL20) and one functional module. The 54 MeDEGs were mainly involved in the regulation of fibroblast growth factor production, the molecular function of arachidonic acid, and ubiquitin-protein transferase activity. Data collected from DisGeNET showed that 11 of the 54 MeDEGs were involved in obesity. Conclusion: This study identifies new MeDEGs involved in obesity and assessed their related pathways and functions. These results data may provide a deeper understanding of methylation-mediated regulatory mechanisms of obesity.

Polymorphisms in TIE2 and ANGPT-1 genes are associated with protection against diabetic retinopathy in a Brazilian population

ABSTRACT Objective: The objective of this study was to investigate the association between SNPs in the TIE2 and ANGPT-1 genes and diabetic retinopathy (DR). Subjects and methods: This study comprised 603 patients with type 2 diabetes mellitus (T2DM) and DR (cases) and 388 patients with T2DM for more than 10 years and without DR (controls). The TIE2 rs639225 (A/G) and rs638203 (A/G) SNPs and the ANGPT-1 rs4324901 (G/T) and rs2507800 (T/A) SNPs were genotyped by real-time PCR using TaqMan MGB probes. Results: The G/G genotype of the rs639225/TIE2, the G/G genotype of the rs638203/TIE2 and the T allele of the rs4324901/ANGPT-1 SNPs were associated with protection against DR after adjustment for age, glycated hemoglobin, gender, and presence of hypertension (P = 0.042, P = 0.003, and P = 0.028, respectively). No association was found between the rs2507800/ANGPT-1 SNP and DR. Conclusion: We demonstrated, for the first time, the association of TIE2 rs638203 and rsrs939225 SNPs and ANGPT-1 rs4324901 SNP with protection against DR in a Brazilian population.

The A allele of the rs759853 single nucleotide polymorphism in the AKR1B1 gene confers risk for diabetic kidney disease in patients with type 2 diabetes from a Brazilian population

ABSTRACT Objective: The AKR1B1 gene encodes an enzyme that catalyzes the reduction of glucose into sorbitol. Chronic hyperglycemia in patients with diabetes mellitus (DM) leads to increased AKR1B1 affinity for glucose and, consequently, sorbitol accumulation. Elevated sorbitol increases oxidative stress, which is one of the main pathways related to chronic complications of diabetes, including diabetic kidney disease (DKD). Accordingly, some studies have suggested the rs759853 polymorphism in the AKR1B1 gene is associated with DKD; however, findings are still contradictory. The aim was to investigate the association of the rs759853 polymorphism in the AKR1B1 gene and DKD. Materials and methods: The sample comprised 695 patients with type 2 DM (T2DM) and DKD (cases) and 310 patients with T2DM of more than 10 years' duration, but no DKD (controls). The polymorphism was genotyped by real-time PCR. Results: Allelic and genotype frequencies of this polymorphism did not differ significantly between groups. However, the A/A genotype was associated with risk for DKD after adjustment for gender, triglycerides, BMI, presence of hypertension and diabetic retinopathy, and duration of DM, under both recessive (P = 0.048) and additive (P = 0.037) inheritance models. Conclusion: Our data suggest an association between the AKR1B1 rs759853A/A genotype and risk for DKD in Brazilians T2DM patients.

The rs2442598 polymorphism in the ANGPT-2 gene is associated with risk for diabetic retinopathy in patients with type 1 diabetes mellitus in a Brazilian population

ABSTRACT Objective: As studies have reported the involvement of angiopoietin-2 (ANGPT-2) in the pathogenesis of diabetic retinopathy (DR), the aim of this study was to investigate the association between the ANGPT-2 rs2442598 polymorphism and DR. Materials and methods: This case-control study comprised 107 patients with type 1 diabetes mellitus (T1DM) and DR (cases) and 129 patients with T1DM without DR (controls) and with ≥ 10 years of DM. The ANGPT-2 rs2442598 (G/A) polymorphism was genotyped by real-time PCR using TaqMan MGB probes. Results: Genotype distributions of this polymorphism were consistent with the Hardy-Weinberg equilibrium. The frequency of the rs2442598 A allele was higher in cases compared to controls (p = 0.011). Moreover, the A/A genotype was more frequent in cases than in controls (p = 0.017) and was associated with risk for DR after adjustments for duration of DM, HbA1c, triglycerides, estimated glomerular filtration rate, and hypertension (odds ratio [OR] = 5.19, 95% confidence interval [CI] 1.21-22.27). This association was maintained under recessive (OR = 4.78, 95% CI 1.14-19.99) and additive (OR = 6.861, 95% CI 1.45-32.38) inheritance models. Conclusion: Our data demonstrated, for the first time, an association between the ANGPT-2 rs2442598 A allele and risk for DR in T1DM patients from southern Brazil. Additional studies are necessary to replicate this association in other populations.

Comparison of two techniques for assessing pancreatic islet viability: flow cytometry and fluorescein diacetate/propidium iodine staining

Introduction: The success of islet transplantation for patients with unstable type 1 diabetes mellitus depends, in part, on the number of isolated islets and their quality, which is assessed by functional and viability tests. The test currently employed to evaluate islet viability, used by the Collaborative Islet Transplant Registry to release products for transplantation, is fluorescein diacetate/propidium iodide (FDA/PI) staining. However, the efficacy of this method relies on researcher experience; in this context, a quantitative method may be useful. The aim of this study was to compare islet viability as assessed by flow cytometry and the FDA/PI assay. Methods: Viability was analyzed in islets isolated from 10 male Wistar rats. Upon FDA/PI staining, 50 islets from each animal were analyzed under fluorescence microscopy by two well-trained researchers. For flow cytometry, islets were dispersed and 100 000 single cells were incubated with the 7-amino-actinomycin D (7AAD) fluorophore (dyes necrotic and late apoptotic cells) and the Annexin V-APC antibody (marks early apoptotic cells). Results: A moderate correlation was found between techniques (r = 0.6; p = 0.047). The mean islet viability measured by flow cytometry was higher than that estimated using FDA/PI staining (95.5 ± 1.4% vs 89.5 ± 5.0%; p = 0.002). Conclusions: Although flow cytometry is more expensive and time-consuming than FDA/PI staining, it is a quantitative technique with greater reproducibility that is less subject to inter-observer variability than FDA/PI. Therefore, flow cytometry appears to be the technique of choice when aiming for a more precise determination of islet viability. (AU)

The rs11755527 polymorphism in the BACH2 gene and type 1 diabetes mellitus: case control study in a Brazilian population

ABSTRACT Objective Type 1 diabetes mellitus (T1DM) is an autoimmune disorder caused by a complex interaction between environmental and genetic risk factors. BTB domain and CNC homolog 2 (BACH2) gene encodes a transcription factor that acts on the differentiation and formation of B and T lymphocytes. BACH2 is also involved in the suppression of apoptosis and inflammation in pancreatic beta-cells, indicating a role for it in the development of T1DM. Therefore, the aim of this study was to evaluate the association of the BACH2 rs11755527 single nucleotide polymorphism (SNP) with T1DM. Subjects and methods This case-control study comprised 475 patients with T1DM and 598 nondiabetic individuals. The BACH2 rs11755527 (C/G) SNP was genotyped using real-time PCR with TaqMan MGB probes. Results Genotype distributions of rs11755527 SNP were in accordance with frequencies predicted by the Hardy-Weinberg equilibrium in case and control groups and were similar between groups (P = 0.729). The minor allele frequency was 43.6% in cases and 42.5% in controls (P = 0.604). Moreover, the G allele frequency did not differ between groups when considering different inheritance models and adjusting for age, gender, body mass index, and HLA DR/DQ genotypes of high-risk for T1DM. Although, well-known high-risk T1DM HLA DR/DQ genotypes were associated with T1DM in our population [OR= 7.42 (95% CI 3.34 - 17.0)], this association was not influenced by the rs11755527 SNP. Conclusion The BACH2 rs11755527 SNP seems not to be associated with T1DM in a Brazilian population.

A liberação de citocinas induzida pela morte cerebral não está associada à disfunção primária do enxerto: um estudo de coorte / Brain death-induced cytokine release is not associated with primary graft dysfunction: a cohort study

RESUMO Objetivo: Examinar a associação entre os níveis de citocinas no plasma do doador e o desenvolvimento de disfunção primária do enxerto de órgãos transplantados a partir de doadores falecidos. Métodos: Foram incluídos no estudo de forma prospectiva 17 doadores falecidos e os respectivos 47 pacientes receptores de transplante. Os receptores foram divididos em dois grupos: grupo 1, de pacientes que desenvolveram disfunção primária do enxerto, e grupo 2, de pacientes que não desenvolveram disfunção primária do enxerto. Os níveis de TNF, IL-6, IL-1β, e IFN-γ, avaliados por meio de ELISA, foram comparados entre os grupos. Resultados: Obtiveram-se 69 órgãos, sendo realizados 48 transplantes. Os níveis plasmáticos de citocinas nos doadores não diferiram entre os grupos (em pg/mL): TNF no grupo 1, com 10,8 (4,3 - 30,8) versus no grupo 2, com 8,7 (4,1 - 33,1), com valor de p = 0,63; IL-6 no grupo 1: 1.617,8 (106,7 - 5.361,7) versus no grupo 2: 922,9 (161,7 - 5.361,7), com p = 0,56; IL-1β, no grupo 1: 0,1 (0,1 - 126,1) versus no grupo 2: 0,1 (0,1 - 243,6), com p = 0,60; e IFN-γ, no grupo 1: 0,03 (0,02 - 0,2) versus no grupo 2: 0,03 (0,02 - 0,1), p = 0,93). Obtivemos resultados similares ao examinar separadamente os casos de transplante renal. Conclusão: Nesta amostra de receptores de transplante, os níveis plasmáticos das citocinas TNF, IL-6, IL-1β e IFN-γ nos doadores não se associaram com o desenvolvimento de disfunção primária do enxerto.

ABSTRACT Objective: To examine the association between donor plasma cytokine levels and the development of primary graft dysfunction of organs transplanted from deceased donors. Methods: Seventeen deceased donors and the respective 47 transplant recipients were prospectively included in the study. Recipients were divided into two groups: group 1, patients who developed primary graft dysfunction; and group 2, patients who did not develop primary graft dysfunction. Donor plasma levels of TNF, IL-6, IL-1β, and IFN-γ assessed by ELISA were compared between groups. Results: Sixty-nine organs were retrieved, and 48 transplants were performed. Donor plasma cytokine levels did not differ between groups (in pg/mL): TNF, group 1: 10.8 (4.3 - 30.8) versus group 2: 8.7 (4.1 - 33.1), p = 0.63; IL-6, group 1: 1617.8 (106.7 - 5361.7) versus group 2: 922.9 (161.7 - 5361.7), p = 0.56; IL-1β, group 1: 0.1 (0.1 - 126.1) versus group 2: 0.1 (0.1 - 243.6), p = 0.60; and IFN-γ, group 1: 0.03 (0.02 - 0.2) versus group 2: 0.03 (0.02 - 0.1), p = 0.93). Similar findings were obtained when kidney transplants were analyzed separately. Conclusion: In this sample of transplant recipients, deceased donor plasma cytokines TNF, IL-6, IL-1β, and IFN-γ were not associated with the development of primary graft dysfunction.

Human pancreatic islet transplantation: an update and description of the establishment of a pancreatic islet isolation laboratory

Type 1 diabetes mellitus (T1DM) is associated with chronic complications that lead to high morbidity and mortality rates in young adults of productive age. Intensive insulin therapy has been able to reduce the likelihood of the development of chronic diabetes complications. However, this treatment is still associated with an increased incidence of hypoglycemia. In patients with “brittle T1DM”, who have severe hypoglycemia without adrenergic symptoms (hypoglycemia unawareness), islet transplantation may be a therapeutic option to restore both insulin secretion and hypoglycemic perception. The Edmonton group demonstrated that most patients who received islet infusions from more than one donor and were treated with steroid-free immunosuppressive drugs displayed a considerable decline in the initial insulin independence rates at eight years following the transplantation, but showed permanent C-peptide secretion, which facilitated glycemic control and protected patients against hypoglycemic episodes. Recently, data published by the Collaborative Islet Transplant Registry (CITR) has revealed that approximately 50% of the patients who undergo islet transplantation are insulin independent after a 3-year follow-up. Therefore, islet transplantation is able to successfully decrease plasma glucose and HbA1c levels, the occurrence of severe hypoglycemia, and improve patient quality of life. The goal of this paper was to review the human islet isolation and transplantation processes, and to describe the establishment of a human islet isolation laboratory at the Endocrine Division of the Hospital de Clínicas de Porto Alegre – Rio Grande do Sul, Brazil.

Toll-like receptor 3 (TLR3) and the development of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a chronic, progressive autoimmune disease characterized by metabolic decompensation often leading to dehydration and ketoacidosis. Viral agents seem to play an important role in triggering the autoimmune destruction that leads to the development of T1DM. Among several viral strains investigated so far, the enterovirus family has been consistently associated with the onset of T1DM in humans. One of the mediators of viral damage is the double-stranded RNA (dsRNA) generated during replication and transcription of viral RNA and DNA. The Toll-like receptor 3 (TLR3) gene codes for an endoplasmic receptor of the pattern-recognition receptors (PRRs) family that recognizes dsRNA, plays an important role in the innate immune response triggered by viral infection. Binding of dsRNA to the TLR3 triggers the release of proinflammatory cytokines, such as interferons, which exhibit potent antiviral action; thus, protecting uninfected cells and inducing apoptosis of infected ones. Therefore, the TLR3 gene is a good candidate for the development of T1DM. Within this context, the objective of the present review was to address the role of the TLR3 gene in the development of T1DM. Arch Endocrinol Metab. 2015;59(1):4-12.

The rs1893217 (T/C) polymorphism in PTPN2 gene is not associated with type 1 diabetes mellitus in subjects from Southern Brazil / O polimorfismo rs1893217 (T/C) no gene PTPN2 não está associado com diabetes melito em indivíduos do Sul do Brasil

Objective: To evaluate the association of the PTPN2 rs1893217 polymorphism with T1DM and/or its clinical and laboratory characteristics in a Caucasian population from Southern Brazil. Subjects and methods: Four hundred and eighty six patients with T1DM and 484 non-diabetic subjects were included in the study. Genotyping of the PTPN2 rs1893217 was performed by real-time PCR. Results: Genotype frequencies did not differ between T1DM patients and non-diabetic subjects (P = 0.265). The C allele was observed in 14.5% of the T1DM sample and 12.2% of the non-diabetic group (P = 0.152). Moreover, the frequencies of this variant did not differ statistically between T1DM patients and non-diabetic subjects when assuming recessive, dominant, or additive inheritance models. The clinical and laboratory characteristics of T1DM patients did not differ significantly among the three genotypes of the rs1893217 polymorphism, either. Conclusion: The PTPN2 rs1893217 polymorphism is not significantly associated with T1DM in Caucasian subjects from Southern Brazil. .

Objetivo: Avaliar a associação do polimorfismo rs1893217 no gene PTPN2 com DM1 e/ou suas características clínicas e laboratoriais em uma população de brancos do Sul do Brasil. Sujeitos e métodos: Quatrocentos e oitenta e seis pacientes com DM1 e 484 indivíduos não diabéticos foram incluídos no estudo. A genotipagem do PTPN2 rs1893217 foi realizada por PCR em tempo real. Resultados: As frequências genotípicas não diferiram entre os pacientes com DM1 e indivíduos não diabéticos (p = 0,265). O alelo C foi observado em 14,5% da amostra com DM1 e 12,2% no grupo de não diabéticos (p = 0,152). Além disso, as frequências dessa variante não diferiram estatisticamente entre os pacientes com DM1 e indivíduos não diabéticos considerando-se os modelos de herança recessivo, dominante ou aditivo. As características clínicas e laboratoriais dos pacientes com DM1 também não diferiram significativamente entre os três genótipos do polimorfismo rs1893217. Conclusão: O polimorfismo rs1893217 do gene PTPN2 não está associado com DM1 em brancos do Sul do Brasil. .

The role of interferon induced with helicase C domain 1 (IFIH1) in the development of type 1 diabetes mellitus / O papel do interferon induzido com o domínio C da helicase 1 (IFIH1) no desenvolvimento do diabetes melito tipo 1

Type 1 diabetes mellitus (T1DM) is a chronic, progressive, autoimmune disease characterized by metabolic decompensation frequently leading to dehydration and ketoacidosis. Viral pathogens seem to play a major role in triggering the autoimmune destruction that leads to the development of T1DM. Among several viral strains investigated so far, enteroviruses have been consistently associated with T1DM in humans. One of the mediators of viral damage is the double-stranded RNA (dsRNA) generated during replication and transcription of viral RNA and DNA. The IFIH1 gene encodes a cytoplasmic receptor of the pattern-recognition receptors (PRRs) family that recognizes dsRNA, playing a role in the innate immune response triggered by viral infection. Binding of dsRNA to this PRR triggers the release of proinflammatory cytokines, such as interferons (IFNs), which exhibit potent antiviral activity, protecting uninfected cells and inducing apoptosis of infected cells. The IFIH1 gene appears to play a major role in the development of some autoimmune diseases, and it is, therefore, a candidate gene for T1DM. Within this context, the objective of the present review was to address the role of IFIH1 in the development of T1DM.

O diabetes melito tipo 1 (T1DM) é uma doença autoimune crônica e progressiva caracterizada por descompensações metabólicas frequentemente acompanhadas por desidratação e cetoacidose. Os agentes virais parecem ter um papel importante no desencadeamento da destruição autoimune que leva ao desenvolvimento do T1DM. Entre as cepas virais estudadas até agora, a família dos enterovírus foi consistentemente associada ao surgimento da doença em humanos. Um dos mediadores do dano viral é o RNA fita dupla (RNAfd) gerado durante a replicação e transcrição de RNA e DNA viral. O gene IFIH1 codifica um receptor citoplasmático pertencente à família dos pattern-recognition receptors (PRRs) que reconhece o RNAfd, tendo um papel importante na resposta imune inata desencadeada por infecção viral. A ligação do RNAfd a essa PRR desencadeia a liberação de citocinas pró-inflamatórias como interferons (IFNs), os quais exibem uma potente ação antiviral e têm como objetivo proteger as células não infectadas e induzir apoptose naquelas já contaminadas. O gene IFIH1 parece ter uma participação importante no desenvolvimento de algumas doenças autoimunes. Por isso, esse gene é um candidato ao desenvolvimento do T1DM. Dentro desse contexto, o objetivo da presente revisão foi abordar o papel do IFIH1 no desenvolvimento do T1DM.

The role of the uncoupling protein 1 (UCP1) on the development of obesity and type 2 diabetes mellitus / Papel da proteína desacopladora 1 (UCP1) no desenvolvimento da obesidade e do diabetes melito tipo 2

It is well established that genetic factors play an important role in the development of both type 2 diabetes mellitus (DM2) and obesity, and that genetically susceptible subjects can develop these metabolic diseases after being exposed to environmental risk factors. Therefore, great efforts have been made to identify genes associated with DM2 and/or obesity. Uncoupling protein 1 (UCP1) is mainly expressed in brown adipose tissue, and acts in thermogenesis, regulation of energy expenditure, and protection against oxidative stress. All these mechanisms are associated with the pathogenesis of DM2 and obesity. Hence, UCP1 is a candidate gene for the development of these disorders. Indeed, several studies have reported that polymorphisms -3826A/G, -1766A/G and -112A/C in the promoter region, Ala64Thr in exon 2 and Met299Leu in exon 5 of UCP1 gene are possibly associated with obesity and/or DM2. However, results are still controversial in different populations. Thus, the aim of this study was to review the role of UCP1 in the development of these metabolic diseases.

Está bem estabelecido que fatores genéticos têm papel importante no desenvolvimento do diabetes melito tipo 2 (DM2) e obesidade e que indivíduos suscetíveis geneticamente podem desenvolver essas doenças metabólicas após exposição a fatores de risco ambientais. Assim, grandes esforços têm sido feitos para a identificação de genes associados ao DM2 e/ou à obesidade. A proteína desacopladora 1 (UCP1) é principalmente expressa no tecido adiposo marrom e atua na termogênese, regulação do gasto energético e proteção contra o estresse oxidativo, mecanismos associados tanto à patogênese do DM2 como à obesidade. Portanto, UCP1 é um gene candidato para o desenvolvimento dessas doenças. De fato, diversos estudos relataram que os polimorfismos -3826A/G, -1766A/G e -112A/C na região promotora, Ala64Thr no éxon 2 e Met299Leu no éxon 5 do gene UCP1 estão possivelmente associados à obesidade e/ou ao DM2. Entretanto, os resultados são ainda controversos em diferentes populações. Então, o objetivo deste estudo foi revisar o papel da UCP1 no desenvolvimento dessas doenças metabólicas.

The role of ecto-nucleotide pyrophosphatase/phosphodiesterase 1 in diabetic nephropathy / Papel da ectonucleotídeo pirofosfatase/fosfodiesterase 1 (ENPP1) na nefropatia diabética

The increased prevalence of diabetes mellitus has caused a rise in the occurrence of its chronic complications, such as diabetic nephropathy (DN), which is associated with elevated morbidity and mortality. Familial aggregation studies have demonstrated that besides the known environmental risk factors, DN has a major genetic component. Therefore, it is necessary to identify genes associated with risk for or protection against DN. Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is expressed in several tissues, including the kidneys. Increased levels of ENPP1 expression inhibit tyrosine-kinase activity of the insulin receptor in several cell types, leading to insulin resistance. K121Q polymorphism of the ENPP1 gene seems to be associated with insulin resistance and DN development. The elucidation of genetic factors and their associations will provide better understanding of the pathogenesis of DN and, may consequently, lead to a more effective approach to prevention and treatment.

A crescente prevalência do diabetes melito tem causado aumento na ocorrência das suas complicações crônicas, como a nefropatia diabética (ND), a qual está associada com elevada morbidade e mortalidade. Estudos de agregação familiar demonstram que a ND tem um importante componente genético, além dos conhecidos fatores de risco ambientais. Portanto, existe a necessidade de se identificarem genes associados ao risco ou proteção à ND. A ectonucleotide pyrophosphatase/phosphodiesterase 1(ENPP1) é expressa em vários tecidos, incluindo nos rins. Foi encontrado que níveis aumentados de expressão da ENPP1 inibem a atividade tirosino-quinase do receptor da insulina em vários tipos celulares, causando resistência à insulina. O polimorfismo K121Q do gene ENNP1parece estar associado com resistência à insulina e com o desenvolvimento da ND. A elucidação dos fatores genéticos e de suas associações permitirá um melhor entendimento da patogênese da ND e, consequentemente, poderemos ter uma abordagem mais efetiva em sua prevenção e tratamento.

The role of uncoupling protein 2 (UCP2) on the development of type 2 diabetes mellitus and its chronic complications / Papel da proteína desacopladora 2 (UCP2) no desenvolvimento do diabetes melito tipo 2 e de suas complicações crônicas

It is well established that genetic factors play an important role in the development of type 2 diabetes mellitus (DM2) and its chronic complications, and that genetically susceptible subjects can develop the disease after being exposed to environmental risk factors. Therefore, great efforts have been made to identify genes associated with DM2. Uncoupling protein 2 (UCP2) is expressed in several tissues, and acts in the protection against oxidative stress; in the negative regulation of insulin secretion by beta cells, and in fatty acid metabolism. All these mechanisms are associated with DM2 pathogenesis and its chronic complications. Therefore, UCP2 is a candidate gene for the development of these disorders. Indeed, several studies have reported that three common polymorphisms in UCP2 gene are possibly associated with DM2 and/or obesity. Only a few studies investigated these polymorphisms in relation to chronic complications of diabetes, with inconclusive results.

Está bem estabelecido que fatores genéticos têm papel importante no desenvolvimento do diabetes melito tipo 2 (DM2) bem como de suas complicações crônicas e que indivíduos geneticamente suscetíveis podem desenvolver essa doença após exposição a fatores de risco ambientais. Assim, grandes esforços têm sido feitos para a identificação de genes associados ao DM2. A proteína desacopladora 2 (UCP2) é expressa em diversos tecidos e atua na proteção contra o estresse oxidativo, na regulação negativa da secreção de insulina pelas células-beta e no metabolismo dos ácidos graxos, mecanismos associados tanto à patogênese do DM2 como a suas complicações crônicas. Portanto, o gene UCP2 é um gene candidato para o desenvolvimento dessas doenças. De fato, diversos estudos têm relatado que três polimorfismos comuns no gene UCP2 estão possivelmente associados ao DM2 e/ou à obesidade. Apenas poucos estudos investigaram esses polimorfismos em relação às complicações crônicas do diabetes, obtendo resultados pouco conclusivos.

Papel do fator de crescimento vascular endotelial na angiogênese e na retinopatia diabética / The role of vascular endothelial growth factor in angiogenesis and diabetic retinopathy

A retinopatia diabética (RD) é uma complicação microvascular do diabetes melito, sendo importante causa de cegueira adquirida. Fatores angiogênicos, como o vascular endothelial growth factor (VEGF), estão envolvidos na patogênese da RD. O VEGF-A é uma citocina potente e multifuncional que atua por meio dos receptores VEGFR-1 e VEGFR-2 expressos no endotélio vascular causando aumento da permeabilidade vascular e estímulo à neovascularização em processos fisiológicos e patológicos. O VEGFR-2 é o principal mediador mitogênico, angiogênico e do aumento da permeabilidade vascular. Alguns polimorfismos do VEGF têm sido estudados na suscetibilidade e risco de progressão da RD. Importante associação entre o polimorfismo 634C/G e a presença de RD é relatada principalmente em relação ao alelo C. A homozigose CC estaria relacionada à RD proliferativa (RDP) e a níveis sérico e vítreo aumentados de VEGF, sugerindo que a presença do alelo C seja um fator de risco independente para RD. Os conhecimentos sobre o VEGF levaram ao desenvolvimento de agentes antiVEGF com o objetivo de inibir a neovascularização patológica e são uma realidade na prática médica do tratamento da RD.

Diabetic retinopathy (DR), a DM microvascular complication, is the leading cause of blindness. Angiogenic factors such as vascular endothelial growth factor (VEGF) are involved in the pathogenesis of DR. VEGF-A is a potent, multifunctional cytokine that acts through the receptors VEGFR-1 and VEGFR-2 expressed in the vascular endothelium and causing increased vascular permeability and neovascularization stimulation in both physiological and pathological processes. The expression of VEGFR-1 is upregulated by hypoxia and is less responsive to VEGF compared to VEGFR-2 which is the main mediator mitogenic, angiogenic, and increased vascular permeability. VEGF polymorphisms have been studied in DR susceptibility and progression. Significant association between the polymorphism 634C / G and the presence of RD is reported mainly in relation to allele C. The homozygous CC is associated to proliferative RD and to increased vitreous and serum levels of VEGF suggesting that the presence of the C allele is an independent risk factor for RD. The knowledgement of VEGF lead to the development of anti-VEGF drugs (pegaptanib, ranibizumab and bevacizumab) aiming to prevent pathological neovascularization. The anti-VEGF therapy is a reality in practice medical treatment of DR.

Genetics of diabetic nephropathy / Bases genéticas da nefropatia diabética

The increasing prevalence of diabetes mellitus has led to a growing number of chronic complications including diabetic nephropathy (DN). In addition to its high prevalence, DN is associated with high morbidity and mortality especially due to cardiovascular diseases. It is well established that genetic factors play a role in the pathogenesis of DN and genetically susceptible individuals can develop it after being exposed to environmental factors. DN is probably a complex, polygenic disease. Two main strategies have been used to identify genes associated to DN: analysis of candidate genes, and more recently genome-wide scan. Great efforts have been made to identify these main genes, but results are still inconsistent with different genes associated to a small effect in specific populations. The identification of the main genes would allow the detection of those individuals at high risk for DN and better understanding of its pathophysiology as well.

A crescente elevação na prevalência do diabetes melito (DM) acarretou em um aumento de suas complicações crônicas, entre elas a nefropatia diabética (ND). Além da elevada prevalência, a ND está associada à importante morbidade e mortalidade, principalmente por doenças cardiovasculares. É notória a contribuição genética na patogênese da ND, em que, na presença de fatores ambientais propícios, aqueles indivíduos geneticamente predispostos desenvolverão a doença. Trata-se de uma doença com provável transmissão genética do tipo poligênica e complexa. Duas estratégias principais têm sido utilizadas na busca dos genes associados à ND: a avaliação de genes candidatos e, mais recentemente, a utilização de genoma wide scan. Grande empenho tem sido realizado para identificar os principais genes associados à ND, mas os resultados ainda são heterogêneos com diferentes genes apresentando um efeito pequeno em populações específicas. A identificação dos principais genes permitiria prever os indivíduos de maior risco para o desenvolvimento da ND, além de possibilitar um melhor entendimento fisiopatológico da doença.

Transplante de ilhotas pancreáticas humanas: revisão da literatura e implantação de um laboratório de isolamento de ilhotas pancreáticas / Human pancreatic islet transplantation: literature review and establishment of a pancreatic islet isolation laboratory

O diabetes melito tipo 1 (DM1) está associado ao desenvolvimento de complicações crônicas de elevada morbi-mortalidade em indivíduos jovens em idade produtiva. A terapia intensiva com insulina comprovadamente diminui o aparecimento das complicações crônicas da doença. Entretanto, essa terapia ainda está associada ao aumento da incidência de hipoglicemia. Em pacientes com “DM1 lábil”, os quais apresentam hipoglicemias graves sem sintomas de alerta, o transplante de ilhotas pancreáticas humanas é uma das melhores alternativas para restaurar a secreção de insulina e a percepção da hipoglicemia. Cerca de 80% dos pacientes que receberam transplante de ilhotas de mais de um doador, submetidos ao tratamento imunossupressor do protocolo de Edmonton, adquiriram independência de insulina após 1 ano do transplante. Porém, apenas 10% destes pacientes permaneceram livres de insulina após 5 anos. Entretanto, mesmo aqueles pacientes que necessitaram utilizar novamente insulina tiveram a normalização da homeostase glicêmica e da percepção da hipoglicemia, com prevenção da hipoglicemia grave. Sendo assim, o transplante de ilhotas é capaz de diminuir os níveis de glicose plasmática e HbA1c, reduzir a ocorrência de hipoglicemias graves e melhorar a qualidade de vida dos pacientes. O objetivo deste artigo foi fazer uma breve revisão da literatura sobre o isolamento e transplante de ilhotas pancreáticas humanas e relatar a implantação de um laboratório de isolamento de ilhotas humanas no Serviço de Endocrinologia do Hospital de Clínicas de Porto Alegre.

Type 1 diabetes mellitus (DM1) is associated with chronic complications of high morbidity and mortality in young adults in a productive age. Insulin therapy has proved to reduce the chronic complications of diabetes. However, this therapy is still associated to an increased incidence of hypoglycemia. In patients with “brittle DM1”, who have severe hypoglycemia without any symptoms (hypoglycemia unawareness), the pancreatic islet transplantation is one of the best alternatives for restoring insulin secretion and hypoglycemia perception. About 80% of the patients who received islet transplantation from more than one donor, on immunosuppressive treatment with the Edmonton’s protocol, maintained insulin independence 1 year after transplantation. Nevertheless, only 10% of these patients remained free of insulin after 5 years post-transplantation. However, even those patients who returned to insulin treatment had a normalization of the glucose homeostasis and hypoglycemia perception. Therefore, islet transplantation is able to diminish plasmatic glucose and HbA1c levels, to reduce the occurrence of severe hypoglycemia, and to improve the quality of life of the patients. The purpose of this paper is to briefly review islet isolation and transplantation process, and report the establishing of a human islet isolation laboratory in the Endocrine Service at Hospital de Clínicas de Porto Alegre.

Prevalence of 15 mitochondrial DNA mutations among type 2 diabetic patients with or without clinical characteristics of maternally inherited diabetes and deafness / Prevalência de 15 mutações no DNA mitocondrial entre pacientes diabéticos tipo 2 com ou sem características clínicas de diabetes e surdez herdados maternalmente

The aim of the present study is to investigate the prevalence of ten described mitochondrial DNA (mtDNA) mutations in patients with type 2 diabetes, and search for new mutations in four mtDNA genes in a subgroup of patients with characteristics of maternally inherited diabetes and deafness (MIDD). These mutations were investigated in 407 type 2 diabetic patients without characteristics of mitochondrial diabetes ("classical" type 2 diabetes group) and in 38 type 2 diabetic patients with characteristics suggestive of MIDD. Through sequencing of four mtDNA genes in MIDD patients, we selected five others potentially pathogenic mutations that were also screened in the remaining patients. Overall, the frequency of the fifteen analyzed mutations was 36.84 percent in the MIDD group and 2.45 percent in the "classical" type 2 diabetes group (p < 0.001). In conclusion, our study reinforces the importance of mtDNA mutations in the pathogenesis of MIDD.

Os objetivos deste estudo foram investigar a prevalência de dez mutações conhecidas no DNA mitocondrial (mtDNA) em pacientes com diabetes tipo 2, e procurar por novas mutações em quatro genes mitocondriais em um subgrupo de pacientes com características de MIDD (Maternally Inherited Diabetes and Deafness). Estas mutações foram investigadas em 407 pacientes diabéticos tipo 2 sem características de diabetes mitocondrial (grupo de diabetes tipo 2 clássico) e em 38 pacientes com diabetes tipo 2 e com características sugestivas de MIDD. Através do seqüenciamento de quatro genes mitocondriais nos pacientes com MIDD, selecionou-se cinco outras mutações potencialmente patogênicas que também foram investigadas no restante dos pacientes. De uma forma geral, a freqüência total das 15 mutações analisadas foi de 36,8 por cento no grupo de pacientes com MIDD e de 2,4 por cento no grupo de diabetes tipo 2 clássico (p < 0,001). Em conclusão, nosso estudo reforça a importância de mutações mitocondriais na patogênese do MIDD.

Familial history of type 2 diabetes in patients from Southern Brazil and its influence on the clinical characteristics of this disease / História familiar de diabetes tipo 2 em pacientes do sul do Brasil e sua influência nas características dessa doença

OBJECTIVE: To investigate the presence of maternal and paternal history of type 2 diabetes mellitus (DM) in relatives of 644 type 2 diabetic patients from Southern Brazil, and also to evaluate its influence on the clinical characteristics of this disease. PATIENTS AND METHODS: Familial history of type 2 DM was investigated by a questionnaire. The maternal and paternal history was investigated over two generations. Complete data sets on familial history were obtained from 396 patients. RESULTS: In general, 76.6 percent of the patients reported at least one first-degree affected relative. Besides, 31.6 percent of the patients reported a maternal history of type 2 DM and 12.6 percent reported a paternal history. Patients with maternal and/or paternal history presented a lower age at type 2 DM diagnosis when compared to patients without familial history. In addition, patients with only paternal history presented a higher frequency of hypertension than patients with no familial history. CONCLUSIONS: This study suggests that there is a significant maternal effect in the transmission of type 2 DM in Southern Brazil, and that most of the clinical characteristics of this disease do not differ between patients with or without familial history of type 2 DM.

OBJETIVOS: Investigar a presença de história materna e paterna de diabetes mellitus tipo 2 (DM) entre familiares de 644 pacientes diabéticos tipo 2 provenientes do sul do Brasil, bem como avaliar sua influência nas características clínicas dessa doença. MATERIAIS E MÉTODOS: A história familiar de DM tipo 2 foi investigada através de um questionário, sendo que a presença de história materna e paterna foi investigada em duas gerações. Dados completos sobre história familiar foram obtidos para 396 pacientes. RESULTADOS: Em geral, 76,6 por cento dos pacientes reportaram ao menos um familiar em primeiro grau afetado por DM tipo 2. Além disso, 31,6 por cento dos pacientes relataram uma história materna de DM tipo 2 e 12,6 por cento relataram uma história paterna. Pacientes com história materna e/ou paterna apresentaram uma idade de diagnóstico de DM tipo 2 mais baixa quando comparado a pacientes sem história familiar. Adicionalmente, pacientes que relataram apenas história paterna de DM tipo 2 apresentaram uma maior freqüência de hipertensão do que pacientes sem história familiar. CONCLUSÕES: Nosso estudo sugere que há um efeito materno significativo na transmissão do DM tipo 2 no Sul do Brasil, e que a maioria das características clínicas dessa doença não difere entre pacientes com e sem história familiar de DM tipo 2.