tiRNA-Val promotes angiogenesis via Sirt1-Hif-1α axis in mice with diabetic retinopathy

BACKGROUND: Diabetic retinopathy (DR) is a specific microvascular complication arising from diabetes, and its pathogenesis is not completely understood. tRNA-derived stress-induced RNAs (tiRNAs), a new type of small noncoding RNA generated by specific cleavage of tRNAs, has become a promising target for several diseases. However, the regulatory function of tiRNAs in DR and its detailed mechanism remain unknown. RESULTS: Here, we analyzed the tiRNA profiles of normal and DR retinal tissues. The expression level of tiRNA-Val was significantly upregulated in DR retinal tissues. Consistently, tiRNA-Val was upregulated in human retinal microvascular endothelial cells (HRMECs) under high glucose conditions. The overexpression of tiRNA-Val enhanced cell proliferation and inhibited cell apoptosis in HRMECs, but the knockdown of tiRNA-Val decreased cell proliferation and promoted cell apoptosis. Mechanistically, tiRNA-Val, derived from mature tRNA-Val with Ang cleavage, decreased Sirt1 expression level by interacting with sirt1 3'UTR, leading to the accumulation of Hif-1α, a key target for DR. In addition, subretinal injection of adeno-associated virus to knock down tiRNA-Val in DR mice ameliorated the symptoms of DR. CONCLUSION: tiRNA-Val enhance cell proliferation and inhibited cell apoptosis via Sirt1/Hif-1α pathway in HRMECs of DR retinal tissues.

Protective effect of ginsenoside Rg_1 aganist diabetic retinopathy by inhibiting NLRP3 inflammasome in type 2 diabetic mice / 中国中药杂志

Ginsenoside Rg_1, one of the main active components of precious traditional Chinese medicine Ginseng Radix et Rhizoma, has the anti-oxidative stress, anti-inflammation, anti-aging, neuroprotection, and other pharmacological effects. Diabetic retinopathy(DR), the most common complication of diabetes, is also the main cause of impaired vision and blindness in the middle-aged and the elderly. The latest research shows that ginsenoside Rg_1 can protect patients against DR, but the protection and the mechanism are rarely studied. This study mainly explored the protective effect of ginsenoside Rg_1 against DR in type 2 diabetic mice and the mechanism. High fat diet(HFD) and streptozotocin(STZ) were used to induce type 2 diabetes in mice, and hematoxylin-eosin(HE) staining was employed to observe pathological changes in the retina of mice. The immunohistochemistry was applied to study the localization and expression of nucleotide-binding oligomerization domain-like receptors 3(NLRP3) and vascular endothelial growth factor(VEGF) in retina, and Western blot was used to detect the expression of nuclear factor-kappa B(NF-κB), p-NF-κB, NLRP3, caspase-1, interleukin-1β(IL-1β), transient receptor potential channel protein 6(TRPC6), nuclear factor of activated T-cell 2(NFAT2), and VEGF in retina. The results showed that ginsenoside Rg_1 significantly alleviated the pathological injury of retina in type 2 diabetic mice. Immunohistochemistry results demonstrated that ginsenoside Rg_1 significantly decreased the expression of NLRP3 and VEGF in retinal ganglion cells, middle plexiform layer, and outer plexiform layer in type 2 diabetic mice. According to the Western blot results, ginsenoside Rg_1 significantly lowered the expression of p-NF-κB, NLRP3, caspase-1, IL-1β, TRPC6, NFAT2, and VEGF in retina of type 2 diabetic mice. These findings suggest that ginsenoside Rg_1 can significantly alleviate DR in type 2 diabetic mice, which may be related to inhibition of NLRP3 inflammasome and VEGF. This study provides experimental evidence for the clinical application of ginsenoside Rg_1 in the treatment of DR.

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.

Association between the RAGE (receptor for advanced glycation end-products) -374T/A gene polymorphism and diabetic retinopathy in T2DM

Summary Objective: Interaction between advanced glycation end-products (AGEs) and receptor for AGEs (RAGE) in cells could affect both extracellular and intracellular structure and function, which plays a pivotal role in diabetic microvascular complications. The results from previous epidemiological studies on the association between RAGE gene -374T/A polymorphism and diabetic retinopathy (DR) risk were inconsistent. Thus, we conducted this meta-analysis to summarize the possible association between RAGE -374T/A polymorphism and DR risk. Method: We searched all relevant articles on the association between RAGE -374T/A polymorphism and DR risk from PubMed, Cochrane Library, ScienceDirect, Wanfang, VIP and Chinese National Knowledge Infrastructure (CNKI) web databases up to August 2016. Odds ratio (OR) with 95% confidence interval (CI) were calculated to assess those associations. All analyses were performed using the Review Manager software. Results: Nine case-control studies, including 1,705 DR cases and 2,236 controls were enrolled, and the results showed that the A allele of RAGE -374T/A polymorphism was significantly associated with increased DR risk in dominant model (TA/AA vs. TT: OR=1.22, 95CI 1.05-1.41, p=0.006) and heterozygote model (TA vs. TT: OR=1.26, 95CI 1.07-1.47, p=0.005). The subgroup analysis by ethnicity showed that significantly increased DR risk was found in both Asian and Caucasian populations. Conclusion: This meta-analysis reveals that the A allele of RAGE -374T/A polymorphism probably increase DR risk.

Comparisons of serum miRNA expression profiles in patients with diabetic retinopathy and type 2 diabetes mellitus

OBJECTIVES: The aim of this study was to compare the expression levels of serum miRNAs in diabetic retinopathy and type 2 diabetes mellitus. METHODS: Serum miRNA expression profiles from diabetic retinopathy cases (type 2 diabetes mellitus patients with diabetic retinopathy) and type 2 diabetes mellitus controls (type 2 diabetes mellitus patients without diabetic retinopathy) were examined by miRNA-specific microarray analysis. Quantitative real-time polymerase chain reaction was used to validate the significantly differentially expressed serum miRNAs from the microarray analysis of 45 diabetic retinopathy cases and 45 age-, sex-, body mass index- and duration-of-diabetes-matched type 2 diabetes mellitus controls. The relative changes in serum miRNA expression levels were analyzed using the 2-ΔΔCt method. RESULTS: A total of 5 diabetic retinopathy cases and 5 type 2 diabetes mellitus controls were included in the miRNA-specific microarray analysis. The serum levels of miR-3939 and miR-1910-3p differed significantly between the two groups in the screening stage; however, quantitative real-time polymerase chain reaction did not reveal significant differences in miRNA expression for 45 diabetic retinopathy cases and their matched type 2 diabetes mellitus controls. CONCLUSION: Our findings indicate that miR-3939 and miR-1910-3p may not play important roles in the development of diabetic retinopathy; however, studies with a larger sample size are needed to confirm our findings.

Relação dos polimorfismos funcionais -509C>t e 869T>C no gene do TGFß1 com a retinopatia e nefropatia diabéticas em pacientes com diabetes mellitus tipo 2 / Relationship of functional polymorphisms -509C>T and 869T>C in the TGFß1 gene with diabetic retinopathy and nephropathy in patients with type 2 diabetes mellitus

Introdução: O fator de crescimento transformante beta-1 (TGFß1) é uma citocina multifuncional que regula a proliferação, a diferenciação e a formação da matriz extracelular de vários tipos de células. Existem evidências de que os polimorfismos -509C>T e 869T>C no gene do TGFß1 alteram a sua expressão gênica e podem estar envolvidos na patogênese das complicações crônicas do diabetes mellitus tipo 2 (DM2). O objetivo deste estudo foi analisar o papel dos polimorfismos funcionais -509C>T e 869T>C no gene do TGFß1 na patogênese da retinopatia (RD) e da nefropatia (ND) diabéticas, em pacientes com DM2. Métodos: Foi realizado um estudo de caso-controle aninhado a um estudo transversal. Foram selecionados pacientes caucasoides com DM2 que realizaram exames clínicos, laboratoriais e uma entrevista com questionário padronizado. A genotipagem dos polimorfismos foi realizada por meio de PCR. Resultados: As frequências genotípicas e alélicas obtidas para o polimorfismo -509C>T nos pacientes com RD ou ND não diferiram daquelas observadas nos pacientes sem estas complicações. Mas quando a gravidade das complicações foi analisada, observou-se que o alelo C foi menos frequente entre os pacientes com insuficiência renal crônica não tratada com diálise, assim como a frequência de homozigotos para o alelo C foi maior nos pacientes dialíticos. Conclusão: Após a análise multivariada, o genótipo CC permaneceu como um fator de risco associado com a progressão da ND (RC = 2,68, IC 95% 1,08-6,68). Assim, os resultados sugerem que o polimorfismo 869T>C no gene do TGFß1 está associado com a progressão da ND em pacientes com DM2 (AU)

Introduction: The transforming growth factor-beta 1 (TGFß1) is a multifunctional cytokine that regulates proliferation, differentiation and extracellular matrix formation of multiple cell types. There is evidence that polymorphisms -509C> T and 869T> C in the TGFß1 gene alter its gene expression and may be involved in the pathogenesis of chronic complications of diabetes mellitus type 2 (DM2). The aim of this study was to analyze the role of functional polymorphisms -509C> T and 869T> C in the TGFß1 gene in the pathogenesis of diabetic retinopathy (DR) and diabetic nephropathy (DN) in patients with DM2. Methods: We conducted a case-control study nested in a cross-sectional study. We selected Caucasian patients with DM2 who underwent clinical and laboratory tests and an interview with a standardized questionnaire. Polymorphism genotyping was performed by PCR. Results: The allele and genotype frequencies obtained for polymorphism -509C> T in patients with DR or DN did not differ from those observed in patients without these complications. But when the severity of complications was analyzed, the C allele was found to be less frequent among patients with chronic renal failure untreated with dialysis, and the frequency of homozygous for the C allele was higher in dialysis patients. Conclusion: After multivariate analysis, the CC genotype remained a risk factor associated with progression of DN (OR = 2.68, 95% CI 1.08 to 6.68). Thus, the results suggest that polymorphism 869T> C in THE TGFß1 gene is associated with progression of DN in patients with DM2 (AU)

Fatores de risco para retinopatia diabética: [revisão] / Diabetic retinopathy risk factors: [review]

A retinopatia diabética (RD) acomete cerca de 95 por cento dos pacientes com diabetes melito tipo 1 (DM1) e 60 por cento dos pacientes com diabetes melito tipo 2 (DM2), sendo a principal causa de cegueira legal em adultos. O objetivo desse manuscrito foi revisar os principais fatores de risco para RD. Os fatores de risco ambientais mais importantes são a hiperglicemia sustentada, os valores elevados de pressão arterial e a longa duração de DM. Entretanto, nem todos os pacientes desenvolvem RD, o que sugere a presença de fatores genéticos, em especial para as formas graves de RD. Diferentes estratégias têm sido utilizadas para avaliar o papel da genética na RD. Estudos de famílias demonstraram agregação familiar de RD. Genes candidatos têm sido estudados (RAGE; VEGF; PPAR-delta; ICAM-1; ECA; ENPP 1; eNOS), observando-se associações positivas ou negativas com a RD. Também alguns cromossomos, em populações selecionadas, foram associados à RD. Finalmente, estudos de expressão genética reforçam a associação de genes candidatos, ou determinam a participação de outros, com a presença da RD. A RD é uma complicação freqüente do DM e junto com os fatores não-genéticos ou ambientais, a identificação de genes relacionados à RD poderá resultar tratamentos mais específicos e eficazes para a RD.

Diabetic retinopathy (DR) occurs in about 95 percent of patients with type 1 diabetes mellitus (DM) and in 60 percent of type 2 DM patients and it is the main cause of legal blindness in adult people. The aim of this manuscript was to review the main risk factors for DR. The major environmental risk factors are hyperglycemia, high blood pressure levels, and long-term duration of DM. However, not all patients will not develop DR, suggesting the presence of a genetic predisposition to DR, especially for severe forms of DR. Special strategies has been used to evaluate the genetic role in DR. Family studies shown that there is a familial aggregation of DR. Candidates genes have been studied (RAGE; VEGF; PPAR-delta; ICAM-1; ECA; ENPP 1; eNOS) and positive or negative associations with DR were demonstrated. Some chromosomes were also associated to DR in selected populations. Finally, genetic expression studies reinforce the association of candidate genes, or participation of others genes, with the presence of DR. DR is a common complication of DM and, along with non-genetic or environmental risk factors, the identification of genes related to DR could result in more specific and efficient DR treatment.

A predisposição genética para o desenvolvimento da microangiopatia no DM1: [revisão] / Genetic susceptibility to microangiopathy development in Type 1 diabetes mellitus: [review]

Acredita-se que o controle glicêmico e a duração do diabetes sejam os fatores de risco mais importantes para o desenvolvimento das microangiopatias diabéticas, contudo, as velocidades de progressão da nefropatia, da retinoaptia e da polineuropatia variam consideravelmente entre os pacientes. Além da presença de fatores de risco, como a hipertensão arterial, a dislipidemia e o fumo, existem evidências sugerindo que uma predisposição genética desempenha um papel na susceptibilidade para as complicações microvasculares. Com base na patogênese dessas complicações crônicas do diabetes, polimorfismos de vários genes candidatos que atuam em diferentes vias desse processo têm sido investigados, como os genes relacionados aos mecanismos dos danos induzidos pela hiperglicemia (os produtos finais de glicação avançada, o aumento na formação de espécies reativas de oxigênio e a atividade aumentada da via da aldose-redutase), os genes relacionados ao sistema renina-angiotensina; os genes que codificam a síntese das citoquinas, dos fatores de crescimento e dos seus receptores e dos transportadores de glicose entre muitos outros. Este artigo discute alguns estudos que corroboram com a importância da predisposição genética no desenvolvimento da microangiopatia diabética.

Glycemic control and diabetes duration are believed to be the most important risk factors for the development of diabetic microangiopathy; however, the rate of progression of nephropathy, retinopathy and polyneuropathy varies considerably among patients. Besides the presence of risk factors such as hypertension, dyslipidaemia and smoking, there is evidence suggesting that genetic predisposition plays a role in the susceptibility to microvascular complications. Based on underlying pathogenesis, polymorphisms of several candidate genes belonging to multiple pathways have been investigated, like the genes related to mechanisms of hyperglycaemia-induced damage (such as advanced glycation end-products and reactive oxygen species increased formation, augmented activity of the aldose reductase pathway); genes related to the renin-angiotensin system; genes coding for cytokines, growth factors and its receptors, glucose transporter; among many others. This article reviews some studies that corroborate the importance of the genetic background in the development of diabetic microangiopathy.

Effect of polymorphisms of the MTHFR and APOE genes on susceptibility to diabetes and severity of diabetic retinopathy in Brazilian patients

Diabetes mellitus (DM) is a highly prevalent complex genetic disorder. There has been a worldwide effort in the identification of susceptibility genes for DM and its complications, and the 5-10-methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein-E (APOE) genes have been considered good candidate susceptibility genes to this condition. The objectives of the present study were to determine if the 677T MTHFR and epsilon2/epsilon3/epsilon4 APOE alleles are risk factors for DM and for severity of diabetic retinopathy (DR). A total of 248 individuals were studied: 107 healthy individuals and 141 diabetic patients (46 with type 1 diabetes and 95 with type 2 diabetes), who also had DR (81 with non-proliferative DR and 60 with proliferative DR). The polymorphisms were analyzed by PCR followed by digestion with restriction enzyme or the single-nucleotide primer extension method. No evidence of association between the 677TT genotype of MTHFR gene and DM [cases: TT = 10/95 (10.6 percent); controls: TT = 14/107 (13 percent)] or with severity of DR was observed [cases: TT = 5/60 (8.5 percent); controls: TT = 9/81 (11.1 percent); P > 0.05]. We also did not find evidence of an association between APOE alleles and proliferative DR (epsilon2, epsilon3 and epsilon4 in cases: 9, 76, and 15 percent, and in controls: 5, 88, and 12 percent, respectively) but the carriers of epsilon2 allele were more frequent among patients with type 2 DM and DR than in controls [cases: 15/95 (15.8 percent); controls: 7/107 (6.5 percent); P < 0.05]. Therefore, our results suggest that the epsilon2 allele/APOE might be a risk factor for diabetes in the Brazilian population.

Genes and diabetic retinopathy.

Several recent studies have provided evidence that good diabetes control is important to prevent diabetic retinopathy. However, some groups of patients develop diabetic retinopathy despite good control and others escape retinopathy despite poor control. This suggests the role of genetic factors in susceptibility to retinopathy. This article reviews the role of genetic factors in determining diabetic retinopathy.

Genotipos del receptor b3- adrenérgico en pacientes con retinopatía diabética no proliferativa y su influencia sobre el perfil de lípidos en el Occidente de México* / Genotypes of adrenergic Beta-3 receptor in patients presenting non-proliferative diabetic retinopathy

Introducción: La Retinopatía Diabética (RD) es una de las complicaciones más frecuentes en la diabetes. El factor de riesgo para desarrollar RD en pacientes con diabetes mellitus tipo 2 es más alta en México-Americanos que en blancos no hispánicos, en donde este alto factor de riesgo en México-Americanos es inexplicable. El receptor b3-Adrenérgico (b3-ADR) se expresa en tejido adiposo blanco y café, donde regula los cambios inducidos por la adrenalina y noradrenalina en el metabolismo energético y la termogénesis. Una mutación en el codón 64 del gen b3-AR origina el cambio del aminoácido triptófano (Trp) por arginina (Arg). Los genotipos Trp64Arg y Arg64Arg se han asociado con incremento de triglicéridos y disminución de HDL-c en pacientes con RD proliferativa. Los objetivos fueron investigar la frecuencia y el efecto de los polimorfismos del b3-AR sobre el perfil de lípidos en pacientes con retinopatía diabética no proliferativa (RDNP) del Occidente de México. Métodos: Se incluyeron 31 pacientes con RDNP clasificados de acuerdo a los criterios del ETDRS Research Group y 25 sujetos clínicamente sanos. Se realizó el perfil de lípidos en todos los pacientes y sujetos sanos incluidos en nuestro estudio. Se realizó extracción de DNA a partir de leucocitos de sangre periférica. Se amplificó una región de 248 pb de la región polimórfica (exón 1) del gen b3-AR por PCR. El producto de PCR (248 pb) fue digerido con la enzima de restricción Mva I. Los patrones de restricción, obtenidos por PCR-RFLP's fueron identificados por electroforesis en gel de agarosa teñidos con bromuro de etidio. El análisis estadístico se llevó a cabo usando las pruebas de ANOVA con Tukey y para las variables cualitativas la prueba de c2 y Pearson. Resultados: Se encontraron niveles altos de CT, TG, LDL-c y VLDL-c en pacientes con RDNP comparado con los sujetos sanos (p=0.03; p=0.0001; p=0.002; p=0.0001 respectivamente). Se identificó una asociación entre los genotipos Trp64Arg y Arg64Arg de los pacientes con RDNP y el genotipo Trp64Trp de los sujetos sanos (p=0.0197). No se identificó asociación entre los genotipos del b3-AR y el perfil de lípidos. Conclusión: Nosotros sugerimos que los genotipos Trp64Arg and Arg64Arg pueden contribuir al desarrollo de la RDNP. Los niveles elevados de CT, TG, LDL-c y VLDL-c en pacientes con RDNP es independiente de los genotipos del b3-AR, pero dependientes de la diabetes mellitus tipo 2.

Polimorfismo del gen de aldosa reductasa y velocidad de aparición de retinopatía en diabéticos no insulinodependientes / Aldose reductase gene polymorphism and rate of appearance of retinopathy in non insulin dependent diabetic patients

Background: Recent studies suggest that polymorphisms associated to the aldose reductase gene could be related to early retinopathy in noninsulin dependent diabetics (NIDDM). There is also new interest on the genetic modulation of coagulation factors in relation to this complication. Aim: To look for a possible relationship between the rate of appearance of retinopathy and the genotype of (AC)n polymorphic marker associated to aldose reductase gene. Patients and methods: A random sample of 27 NIDDM, aged 68.1 ñ 10.6 years, with a mean diabetes duration of 20.7 ñ 4.8 years and a mean glycosilated hemoglobin of 10.6 ñ 1.6 percent, was studied. The genotype of the (AC)n, polymorphic marker associated to the 5Õ end of the aldose reductase (ALR2) gene was determined by 32P-PCR plus sequenciation. Mutations of the factor XIII-A gene were studied by single stranded conformational polymorphism, sequenciation and restriction fragment length polymorphism. Results: Four patients lacked the (AC)24 and had a higher rate of appearance of retinopathy than patients with the (AC)24 allele (0.0167 and 0.0907 score points per year respectively, p=0.047). Both groups had similar glycosilated hemoglobin (11.7 ñ 0.2 and 10.5 ñ 1.6 percent respectively). Factor XIII gene mutations were not related to the rate of appearance of retinopathy. Conclusions: Our data suggest that the absence of the (AC)24 allele of the (AC)n polymorphic marker associated to the 5Õ end of the aldose reductase gene, is associated to a five fold reduction of retinopathy appearance rate

Genetic marker in juvenile diabetic retinopathy.

Thirty five patients with insulin dependent diabetes mellitus (IDDM) were investigated for development of retinal microangiopathy by fluorescein angiography. HLA typing (A,B.C antigens) was done as a genetic marker. There was no statistically significant difference in the frequency of HLA antigens between patients without retinopathy (Gr.I) and with retinopathy (Gr.II) Frequency of various HLA antigens did not differ significantly in the mild and severe retinopathy groups or in comparison with controls. HLA B8 was significantly over represented in the patients of IDDM as a single group (GrI + II) when compared with controls (26% vs 8%). HLA profile was not a predictor of either the development or the severity of retinopathy in IDDM.