Jakeline Rheinheimer

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

Background and objective  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 45 bp insertion/deletion (Ins/Del) polymorphisms in the UCP2 gene might be associated with proliferative DR (PDR).

D2 Thr92Ala and PPARγ2 Pro12Ala polymorphisms interact in the modulation of insulin resistance in type 2 diabetic patients.

Type 2 deiodinase (D2) converts T4 into its active metabolite T3, an essential step in thyroid metabolism. A Thr92Ala polymorphism in the gene encoding D2 has been inconsistently associated with insulin resistance (IR). Recently, it was reported that the D2 Thr92Ala (rs225014) and the peroxisome proliferator‐activated receptor (PPAR) γ2 Pro12Ala (rs1801282) polymorphisms interact in the modulation of metabolic syndrome in nondiabetic subjects. Here, we investigated the effect of both polymorphisms, isolated or in combination, on IR in patients with type 2 diabetes mellitus (DM2). The D2 Thr92Ala and PPARγ2 Pro12Ala polymorphisms were genotyped in 721 DM2 patients. IR was evaluated using the homeostasis model assessment—IR (HOMAIR) index in a subgroup of 246 DM2 subjects. The frequencies of D2 Ala92 and PPARγ2 Ala12 variants were 0.390 and 0.074, respectively. Patients carrying D2 Ala/Ala genotype had a higher fasting plasma insulin and HOMAIR index as compared to patients carrying Thr/Ala or Thr/Thr genotypes (P = 0.022 and P = 0.001, respectively). A significant synergistic effect was observed between D2 Thr92Ala and PPARγ2 Pro12Ala polymorphisms on HOMAIR index, with carriers of both D2 Ala/Ala genotype and PPARγ2 Ala12 allele showing the highest HOMAIR values, after adjusting for age, gender, BMI, and use of medication for DM2 (P = 0.010). In conclusion, DM2 patients harboring both D2 Ala/Ala genotype and PPARγ2 Ala12 allele seem to present more severe IR than those with other D2/PPARγ2 genotype combinations. These findings suggest that these polymorphisms interact in the IR modulation, which may constitute a potential therapeutic target.

Current role of the NLRP3 inflammasome on obesity and insulin resistance: A systematic review

NLRP3 inflammasome activation seems to be a culprit behind the chronic inflammation characteristic of obesity and insulin resistance (IR). Nutrient excess generates danger-associated molecules that activate NLRP3 inflammasome-caspase 1, leading to maturation of IL-1β and IL-18, which are proinflammatory cytokines released by immune cells infiltrating the adipose tissue (AT) from obese subjects. Although several studies have reported an association of the NLRP3 inflammasome with obesity and/or IR; contradictory results were also reported by other studies. Therefore, we conducted a systematic review to summarize results of studies that evaluated the association of the NLRP3 with obesity and IR. Nineteen studies were included in the review. These studies focused on NLRP3 expression/polymorphism analyses in AT. Overall, human studies indicate that obesity and IR are associated with increased NLRP3 expression in AT. Studies in obese mice corroborate this association. Moreover, high fat diet (HFD) increases Nlrp3 expression in murine AT while calorie-restricted diet decreases its expression. Hence, Nlrp3 blockade in mice protects against HFD-induced obesity and IR. NLRP3 rs10754558 polymorphism is associated with risk for T2DM in Chinese Han populations. In conclusion, available studies strongly points for an association between NLRP3 inflammasome and obesity/IR.

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

PURPOSE We tested the hypothesis that tumor necrosis factor (TNF) gene polymorphisms are associated with diabetic retinopathy (DR) in Caucasians with type 2 diabetes mellitus. METHODS In 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). RESULTS Genotype 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). CONCLUSIONS This 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.

The TCF7L2 rs7903146 (C/T) polymorphism is associated with risk to type 2 diabetes mellitus in Southern-Brazil

OBJECTIVE The aim of this study was to investigate the association between the rs7903146 (C/T) polymorphism in the TCF7L2 gene and type 2 diabetes mellitus, in a Southern-Brazilian population. MATERIALS AND METHODS The TCF7L2 rs7903146 polymorphism was genotyped in 953 type 2 diabetic patients and 535 non-diabetic subjects. All subjects were white. The polymorphism was genotyped by Real-Time PCR using TaqMan MGB probes (Life Technologies). Odds ratios (OR) and 95% confidence intervals (CI) were calculated for additive, recessive and dominant inheritance models. RESULTS Genotype and allele frequencies of the rs7903146 polymorphism differed significantly between type 2 diabetic patients and non-diabetic subjects (P = 0.001 and P = 0.0001, respectively). The frequency of the minor allele was 38% in type 2 diabetes group and 31% in non-diabetic subjects, and this allele was significantly associated with type 2 diabetes risk (OR = 1.42, 95% CI 1.15 - 1.76 for the dominant model of inheritance). Moreover, the T/T genotype was associated with a higher risk for type 2 diabetes (OR = 1.83, 95% CI 1.3-2.5) than the presence of only one copy of the T allele (OR = 1.31, 95% CI 1.1-1.6). Both results were adjusted for age and gender. CONCLUSIONS Our results confirm the association between the TCF7L2 rs7903146 polymorphism and increase risk for type 2 diabetes in Southern-Brazil.

Different digestion enzymes used for human pancreatic islet isolation: A mixed treatment comparison (MTC) meta-analysis

Collagenases are critical reagents determining yield and quality of isolated human pancreatic islets and may affect islet transplantation outcome. Some islet transplantation centers have compared 2 or more collagenase blends; however, the results regarding differences in quantity and quality of islets are conflicting. Thus, for the first time, a mixed treatment comparison (MTC) meta-analysis was carried out to compile data about the effect of different collagenases used for human pancreas digestion on islet yield, purity, viability and stimulation index (SI). Pubmed, Embase and Cochrane libraries were searched. Of 755 articles retrieved, a total of 15 articles fulfilled the eligibility criteria and were included in the MTC meta-analysis. Our results revealed that Vitacyte and Liberase MTF were associated with a small increase in islet yield (islet equivalent number/g pancreas) when compared with Sevac enzyme [standardized mean difference (95% credible interval – CrI) = −2.19 (−4.25 to −0.21) and −2.28 (−4.49 to −0.23), respectively]. However, all other enzyme comparisons did not show any significant difference regarding islet yield. Purity and viability percentages were not significantly different among any of the analyzed digestion enzymes. Interestingly, Vitacyte and Serva NB1 were associated with increased SI when compared with Liberase MTF enzyme [unstandardized weighted mean difference (95% CrI) = −1.69 (−2.87 to −0.51) and −1.07 (−1.79 to −0.39), respectively]. In conclusion, our MTC meta-analysis suggests that the digestion enzymes currently being used for islet isolation works with similar efficiency regarding islet yield, purity and viability; however, Vitacyte and Serva NB1 enzymes seem to be associated with an improved SI as compared with Liberase MTF.

Polymorphisms of the UCP2 Gene Are Associated with Glomerular Filtration Rate in Type 2 Diabetic Patients and with Decreased UCP2 Gene Expression in Human Kidney

Introduction Uncoupling protein 2 (UCP2) reduces production of reactive oxygen species (ROS) by mitochondria. ROS overproduction is one of the major contributors to the pathogenesis of chronic diabetic complications, such as diabetic kidney disease (DKD). Thus, deleterious polymorphisms in the UCP2 gene are candidate risk factors for DKD. In this study, we investigated whether UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms were associated with DKD in patients with type 2 diabetes mellitus (T2DM), and whether they had an effect on UCP2 gene expression in human kidney tissue biopsies. Materials and Methods In a case-control study, frequencies of the UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms as well as frequencies of the haplotypes constituted by them were analyzed in 287 T2DM patients with DKD and 281 T2DM patients without this complication. In a cross-sectional study, UCP2 gene expression was evaluated in 42 kidney biopsy samples stratified according to the presence of the UCP2 mutated -866A/55Val/Ins haplotype. Results In the T2DM group, multivariate logistic regression analysis showed that the -866A/55Val/Ins haplotype was an independent risk factor for DKD (OR = 2.136, 95% CI 1.036–4.404), although neither genotype nor allele frequencies of the individual polymorphisms differed between case and control groups. Interestingly, T2DM patients carrying the mutated haplotype showed decreased estimated glomerular filtration rate (eGFR) when compared to subjects with the reference haplotype (adjusted P= 0.035). In kidney biopsy samples, UCP2 expression was significantly decreased in UCP2 mutated haplotype carriers when compared to kidneys from patients with the reference haplotype (0.32 ± 1.20 vs. 1.85 ± 1.16 n fold change; adjusted P< 0.000001). Discussion Data reported here suggest that the UCP2 -866A/55Val/Ins haplotype is associated with an increased risk for DKD and with a lower eGFR in T2DM patients. Furthermore, this mutated haplotype was associated with decreased UCP2 gene expression in human kidneys.

The rs1893217 (T/C) polymorphism in PTPN2 gene is not associated with type 1 diabetes mellitus in subjects from Southern Brazil.

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.

Early reduction of resting energy expenditure and successful weight loss after Roux-en-Y gastric bypass

BACKGROUND Weight loss and body composition changes after Roux-en-Y gastric bypass (RYGB) may influence resting energy expenditure (REE). The effect of lower REE after the procedure on long-term weight remains to be elucidated. OBJECTIVE To evaluate the effects of RYGB on REE and body composition 6 months after RYGB and to find out whether postsurgery REE affects weight at 12 and 18 months SETTING: Tertiary referral hospital, southern Brazil METHOD: A prospective study involving 30 RYGB patients aged>18 years was performed. Body composition was evaluated by X-ray absorptiometry and REE by indirect calorimetry. All patients were assessed before RYGB and 6 months postoperatively. Further analysis of weight was carried out at 12 and 18 months. RESULTS Baseline body mass index was 49±9 kg/m² and mean weight was 128±19 kg, half of which comprised fat mass (50±5%). Baseline mean REE was 2297±182 kcal/d. The percent total weight loss was 26±7%, 32±9%, and 34±9% at 6, 12, and 18 months, respectively. The percent excess weight loss gradually increased from 54 ± 12% at 6 months, to 67 ± 18% at 12 months, and 71 ± 19% at 18 months. REE was significantly lower at follow-up (-405±108 kcal/d; P<.001). Furthermore, an inverse correlation between REE at 6 months and percent excess weight loss at 18 months (r =-.612; P = .035) was observed in the subgroup of patients whose REE decreased>405 kcal/d at 6 months. CONCLUSION Patients undergoing RYGB who had a substantial drop in REE at 6 months may exhibit less long-term weight loss.

Brain Death-Induced Inflammatory Activity is Similar to Sepsis-Induced Cytokine Release

Brain death (BD) is associated with a systemic inflammation leading to worse graft outcomes. This study aimed to compare plasma cytokine values between brain-dead and critically ill patients, including septic and non-septic controls, and evaluate cytokine release kinetics in BD. Sixteen brain-dead and 32 control patients (16 with and 16 without sepsis) were included. Plasma cytokines were measured by magnetic bead assay after the first clinical exam consistent with BD and every 6 hours thereafter, and at the time of study entry in the control group. The values for IL-8 and IFN-γ were higher in brain-dead and septic patients than in non-septic patients [IL-8: 80.3 (18.7–169.6) vs. 68.2 (22.4–359.4) vs. 16.4 (9.2–42.7) pg/mL; P = 0.006; IFN-γ: 2.8 (1.6-6.1) vs. 3.4 (1.2–9.0) vs. 0.5 (0.5–1.8) pg/mL; P = 0.012]. TNF showed a clear tendency to increase in brain-dead patients [2.7 (1.0–4.8) vs. 1.0 (1.0–5.6) vs. 1.0 (1.0–1.0) pg/mL; P = 0.051], and IL-6 values were higher in brain-dead patients than in non-septic controls [174.5 (104.9–692.5) vs. 13.2 (7.3–38.6) pg/mL; P = 0.002]. These differences remained even after excluding brain-dead patients who also had sepsis (n = 3). IL-1β and IL-10 values increased from baseline to time point 2 (∼6 hours later) [IL-1β: 5.39 (1.93–16.89) vs. 7.11 (1.93–29.13) pg/mL; P = 0.012; IL-10: 8.78 (3.62–16.49) vs. 15.73 (5.49–23.98) pg/mL; P = 0.009]. BD-induced and sepsis-induced plasma cytokine values were similarly high, and both were higher than the observed in non-septic critically ill patients.