The associations between VEGF gene polymorphisms and diabetic retinopathy susceptibility: a meta-analysis of 11 case-control studies

Capsiate Improves Glucose Metabolism by Improving Insulin Sensitivity in Diabetic Retinopathy Mice

PURPOSE

Capsiate (cap) is a metabolite that affects a number of biological processes, and diabetic retinopathy (DR) is now known to be the primary cause of end-stage eye illness.

METHODS

In order to examine the effects of the cap intervention on body weight, nutritional intake, changes in body weight composition, glucose metabolism levels, retinopathy, and oxidative stress levels, we proposed using a mouse model of diabetic retinopathy caused by STZ.

RESULTS

Our findings demonstrated that, in addition to increasing lean body mass and lowering fat body mass content, cap intervention significantly improved body weight and dietary consumption in STZ mice. Additionally, our results on glucose metabolism revealed that cap had a significant impact on insulin resistance and the stabilization of OGTT levels. In conclusion, we examined the levels of oxidative stress and retinopathy. We discovered that the cap intervention greatly reduced the levels of MDA and significantly improved the levels of VEGF and retinopathy. In contrast, the STZ group's levels of SOD, CAT, and GSH were significantly higher.

CONCLUSIONS

According to our research, the Cap intervention improved the damage caused by diabetic retinopathy by reversing the levels of oxidative stress and the disrupted state of glucose metabolism, which in turn decreased the levels of VEGF.

The role of mannose-binding lectin (MBL) in diabetic retinopathy: A scoping review

Diabetes mellitus (DM) is a chronic systemic disease characterized by a multifactorial nature, which may lead to several macro and microvascular complications. Diabetic retinopathy (DR) is one of the most severe microvascular complications of DM, which can result in permanent blindness. The mechanisms involved in the pathogenesis of DR are multiple and still poorly understood. Factors such as dysregulation of vascular regeneration, oxidative and hyperosmolar stress in addition to inflammatory processes have been associated with the pathogenesis of DR. Furthermore, compelling evidence shows that components of the immune system, including the complement system, play a relevant role in the development of the disease. Studies suggest that high concentrations of mannose-binding lectin (MBL), an essential component of the complement lectin pathway, may contribute to the development of DR in patients with DM. This review provides an update on the possible role of the complement system, specifically the lectin pathway, in the pathogenesis of DR and discusses the potential of MBL as a non-invasive biomarker for both, the presence and severity of DR, in addition to its potential as a therapeutic target for intervention strategies.

Curative effect of the total saponins of Panax japonicus (TSPJ) on type 2 diabetes: Focusing on VEGFA

OBJECTIVE

The objective of this study was to assess the impact of the total saponins of Panax japonicus (TSPJ) on Type 2 diabetes mellitus (T2DM).

RESULTS

The intervention of TSPJ was found to have the ability to reverse physiological indicators associated with T2DM, while also enhancing the expression of genes involved in glucose metabolism and intestinal homeostasis. Additionally, alterations in the composition of the gut microbiota were observed. Based on the findings of experimental results and network pharmacology analysis, it is evident that vascular endothelial growth factor A (VEGFA) serves as a prominent shared target between TSPJ and diabetes. The outcomes observed in T2DM mice overexpressing VEGFA align with those observed in T2DM mice treated with TSPJ.

CONCLUSIONS

TSPJ administration and VEGFA overexpression yield similar effects on T2DM in mice. Thus, in terms of mechanism, by upregulating the expression of VEGFA, TSPJ may ameliorate metabolic imbalance, preserve intestinal homeostasis, and lessen the symptoms of type 2 diabetes. The findings demonstrated the viability of using VEGFA as a type 2 diabetes therapy option and offered important insights into the therapeutic mechanisms by TSPJ in the management of T2DM. To determine the exact mechanisms behind the effects of TSPJ and VEGFA and to assess their potential therapeutic uses, more research efforts are necessary.

Vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor in diabetic and non-diabetic retinopathy: associated factors and anatomical correlation

BACKGROUND

This study aims to investigate the factors affecting the vitreous levels of pigment epithelium-derived factor (PEDF) and vascular endothelial growth factor (VGEF) among patients with pars plana vitrectomy (PPV). Also, this study correlates the levels of PEDF with RRD characteristics.

METHODS

All patients who were scheduled for PPV for any indication were included in the study. They were divided into a case group which included patients with advanced PDR and a control group which included the remaining diagnoses. During the PPV, an undiluted vitreous sample was taken and the enzyme-linked immunosorbent assay method was utilized to measure the levels of VEGF and PEDF.

RESULTS

Eighty eyes were involved. Patients diagnosed with advanced PDR and endophthalmitis exhibited higher levels of VEGF. PEDF was affected inversely by the age of the patients and PEDF levels were higher in RRD and endophthalmitis cases. In patients with RRD, the level of PEDF was higher if the tear was found inferiorly, if the macula was detached, and with a longer duration of RRD.

CONCLUSIONS

This study highlights the clinical importance of those biomarkers. Anti-VEGF-based treatment is the mainstay against PDR. PEDF may show a promising predictive values regarding patients with RRD.

Microvascular Complications Are Associated With Coronary Collateralization in Type 2 Diabetes and Chronic Occlusion

CONTEXT

Coronary collateral (CC) vessel development appears to be protective with regard to adverse cardiovascular events and survival in patients with coronary chronic total occlusion (CTO). The influence of type 2 diabetes mellitus (T2DM) on CC growth has been controversial. In particular, the role of diabetic microvascular complications (DMC) in determining coronary collateralization has not been elucidated.

OBJECTIVE

To investigate whether patients with DMC presented differences in CC vessel presence and grading as compared with patients without DMC.

METHODS

We conducted a single-center observational study, including consecutive T2DM patients, without previous cardiovascular history, undergoing a clinically indicated coronary angiography for chronic coronary syndrome (CCS) and angiographic evidence of at least one CTO. Patients were subdivided into 2 study groups according to the presence/absence of at least one DMC (neuropathy, nephropathy, or retinopathy). The presence and grading of angiographically visible CC development from the patent vessels to the occluded artery were assessed using the Rentrop classification.

RESULTS

We enrolled 157 patients (mean age 68.6 ± 9.8 years; 120 [76.4%] men). Patients with DMC (75 [47.8%]) had a higher prevalence of CC (69 [92.0%] vs 62 [75.6%], P = .006) and high-grade CC (55 [73.3%] vs 39 [47.6%], P = .001) compared with those without, and we found a positive association between the number of DMC in each patient and the prevalence of high-grade CC.

CONCLUSION

Among T2DM patients with coronary CTO, the presence of DMC was associated with a high CC development.

Vitreous Levels of Vascular Endothelial Growth Factor and Platelet-Derived Growth Factor in Patients with Proliferative Diabetic Retinopathy: A Clinical Correlation

Background: The global epidemic status of diabetic retinopathy (DR) and its burden presents an ongoing challenge to health-care systems. It is of great interest to investigate potential prognostic biomarkers of DR. Such markers could aid in detecting early stages of DR, predicting DR progression and its response to therapeutics. Herein, we investigate the prognostic value of intravitreal concentrations of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) in a DR cohort. Materials and methods: Vitreous sample acquisition was conducted at King Abdullah University Hospital (KAUH) between December 2020 and June 2022. Samples were obtained from any patient scheduled to undergo a pars plana vitrectomy (PPV) for any indication. Included patients were categorized into a DR group or a corresponding non-diabetic (ND) control group. Demographics, clinicopathological variables, standardized laboratory tests results, and optical coherence tomography (OCT) data were obtained for each included individual. Intravitreal concentrations of VEGF and PDGF were assessed using commercial enzyme-linked immunosorbent assay (ELISA). Results: A total of 80 eyes from 80 patients (DR group: n = 42 and ND control group: n = 38) were included in the analysis. The vitreous VEGF levels were significantly higher in the DR group compared to the ND control group (DR group 5744.06 ± 761.5 pg/mL versus ND control group 817.94 ± 403.1 pg/mL, p = 0.0001). In addition, the vitreous PDGF levels were also significantly higher in the DR group than those in the ND control group (DR group 4031.51 ± 410.2 pg/mL versus ND control group 2691.46 ± 821.0 pg/mL, p = 0.001). Bassline differences between test groups and clinical factors impacting VEGF and PDGF concentrations were investigated as well. Multiple regression analysis indicated PDGF as the sole independent risk factor affecting best-corrected visual acuity (BCVA) at the last follow-up visit: the higher the PDGF vitreous levels, the worst the BCVA. Conclusions: Vitreous concentrations of VEGF and PDGF are correlated with DR severity and may exhibit a possible prognostic potential value in DR. Further clinical and experimental data are warranted to confirm the observed findings and to help incorporate them into daily practice.

Endothelial to mesenchymal cell transition in diabetic retinopathy: targets and therapeutics

Diabetic retinopathy (DR) is a result of neurovacular insults from hyperglycemia in diabetes mellitus (DM), and it is one of the top causes of vision loss throughout the modern world. This review article explores the role endothelial to mesenchymal transition (EndMT) has on the pathogenesis of DR. EndMT contributes to the disruption of the blood-retinal barrier, vascular leakage, neovascularization, and fibrosis observed in DR. Risk factors and biomarkers associated with DR severity are discussed, highlighting the importance of early detection and targeted therapies. Current treatments primarily focus on anti-vascular endothelial growth factor (anti-VEGF) agents, corticosteroids, and laser photocoagulation. However, emerging therapeutic strategies aimed at inhibiting EndMT and its downstream effects show promise in preventing the development and progression of DR. Understanding the molecular and cellular mechanisms underlying EndMT in DR provides valuable insights into the disease process and offers potential options for the development of potential treatments.

Genetic Polymorphisms of Vascular Endothelial Growth Factor in Neonatal Pathologies: A Systematic Search and Narrative Synthesis of the Literature

(1) Background: Vascular endothelial growth factor (VEGF) is essential in vasculo- and angiogenesis due to its role in endothelial cell proliferation and migration. As a vascular proliferative factor, VEGF is one of the hallmarks of cancer and, in adult populations, the relationship between genetic polymorphism and neoplasm was widely investigated. For the neonatal population, only a few studies attempted to uncover the link between the genetic polymorphism of VEGF and neonatal pathology, especially related to late-onset complications. Our objective is to evaluate the literature surrounding VEGF genetic polymorphisms and the morbidity of the neonatal period. (2) Methods: A systematic search was initially conducted in December 2022. The PubMed platform was used to explore MEDLINE (1946 to 2022) and PubMed Central (2000 to 2022) by applying the search string ((VEGF polymorphism*) and newborn*). (3) Results: The PubMed search yielded 62 documents. A narrative synthesis of the findings was undertaken considering our predetermined subheadings (infants with low birth weight or preterm birth, heart pathologies, lung diseases, eye conditions, cerebral pathologies, and digestive pathologies). (4) Conclusion: The VEGF polymorphisms seem to be associated with neonatal pathology. The involvement of VEGF and VEGF polymorphism has been demonstrated for retinopathy of prematurity.

Association between the VEGFR-2 -604T/C polymorphism (rs2071559) and type 2 diabetic retinopathy

This retrospective case-control study examined the association between the rs2071559 (-604T/C) single nucleotide polymorphism (SNP) in the vascular endothelial growth factor receptor (VEGFR)-2 gene and the risk of diabetic retinopathy (DR) in Northern Han Chinese. This study included patients diagnosed with diabetes mellitus (DM) in Shijiazhuang between 07/2014 and 07/2016. The healthy controls were unrelated individuals who received routine physical examinations. The diabetic patients were grouped as DM (diabetes but no fundus examination abnormalities), proliferative DR (PDR), and non-proliferative DR (NPDR). Finally, 438 patients were included: 114 controls and 123, 105, and 96 patients in the DM, NPDR, and PDR groups, respectively. In the multivariable analyses and all genetic models, the VEGFR-2 rs2071559 SNP was not associated with DR (among all diabetic patients) or with PDR (among the patients with DR) after adjustment for age, sex, duration of DM, blood glucose, systolic blood pressure, diastolic blood pressure, and body mass index (all P > 0.05). In conclusion, the VEGFR-2- 604T/C rs2071559 SNP is not associated with DR or PDR in the Han Chinese population of Shijiazhuang (China).

Association study of HIF-1α rs11549465 and VEGF rs3025039 genetic variants with diabetic retinopathy in Egyptian patients: crosslinks with angiogenic, inflammatory, and anti-inflammatory markers

Background

Genetic factors are implicated in the progression of DR—a global cause of blindness. Hence, the current work investigated the association of HIF-1α rs11549465 and VEGF rs3025039 genetic variants with the different stages of retinopathy among T2DM Egyptian patients. The crosslinks of these variants were explored with angiogenesis (VEGF), inflammation (AGEP and VCAM-1), and anti-inflammation (CTRP3) markers. Two hundred eighty-eight subjects were recruited in this study: 72 served as controls and 216 were having T2DM and were divided into diabetics without retinopathy (DWR), diabetics with non-proliferative retinopathy (NPDR), and diabetics with proliferative retinopathy (PDR). The genetic variants were analyzed using PCR-RFLP and their associations with NPDR and PDR were statistically tested. The circulating levels of AGEP, VCAM-1, HIF-1α, VEGF, and CTRP3 were assayed followed by analyzing their associations statistically with the studied variants.

Results

Only HIF-1α rs11549465 genetic variant (recessive model) was significantly associated with the development of NPDR among T2DM patients (p < 0.025) with a significant correlation with the circulating HIF-1α level (p < 0.0001). However, this variant was not associated with PDR progression. Neither HIF-1α rs11549465 nor VEGF rs3025039 genetic variants were associated with the PDR progression. The circulating AGEP, VCAM-1, HIF-1α, and VEGF were significantly elevated (p < 0.0001) while the CTRP3 was significantly decreased (p < 0.0001) in NPDR and PDR groups. The HIF-1α rs11549465 CT and/or TT genotype carriers were significantly associated with AGEP and VCAM-1 levels in the NPDR group, while it showed a significant association with the CTRP3 level in the PDR group. The VEGF rs3025039 TT genotype carriers showed only a significant association with the CTRP3 level in the PDR group.

Conclusion

The significant association of HIF-1α rs11549465 other than VEGF rs3025039 with the initiation of NPDR in T2DM Egyptian patients might protect them from progression to the proliferative stage via elevating circulating HIF-1α. However, this protective role was not enough to prevent the development of NPDR because of enhancing angiogenesis and inflammation together with suppressing anti-inflammation. The non-significant association of HIF-1α rs11549465 with PDR among T2DM patients could not make this variant a risk factor for PDR progression.

Variants of SLC2A10 may be Linked to Poor Response to Metformin

Purpose

A study among Filipinos revealed that only 15% of patients with diabetes achieved glycemic control, and poor response to metformin could be one of the possible reasons. Recent studies demonstrate how genetic variations influence response to metformin. Hence, the present study aimed to determine genetic variants associated with poor response to metformin.

Methods

Using a candidate variant approach, 195 adult Filipino participants with newly diagnosed type 2 diabetes mellitus (T2DM) were enrolled in a case-control study. Genomic DNA from blood samples were collected. Allelic and genotypic associations of variants with poor response to metformin were determined using exact statistical methods.

Results

Several polymorphisms were nominally associated with poor response to metformin (P_uncorr < 0.05). The most notable is the association of multiple variants in the SLC2A10 gene—rs2425911, rs3092412, and rs2425904—with common additive genetic mode of inheritance. Other variants that have possible associations with poor drug response include rs340874 (PROX-AS1), rs815815 (CALM2), rs1333049 (CDKN2B-AS1), rs2010963 (VEGFA), rs1535435 and rs9494266 (AHI1), rs11128347 (PDZRN3), rs1805081 (NPC1), and rs13266634 (SLC30A8).

Conclusion

In Filipinos, a trend for the association for several variants was noted, with further observation that several mechanisms may be involved. The results may serve as pilot data for further validation of candidate variants for T2DM pharmacotherapy.

A study of the genotyping and vascular endothelial growth factor polymorphism differences in diabetic and diabetic retinopathy patients

Background

Retinopathy is one of the major causes of visual impairment which is the most severe microvascular complication of diabetes mellitus (DM). The aim of this study was to evaluate the association between diabetic retinopathy (DR) and two SNPs (− 152G > A and − 165C > T) located in the promoter region of the vascular endothelial growth factor (VEGF) gene in a small sample from Egyptian population. One hundred diabetic patients without retinopathy (DWR) and two hundred diabetic patients with retinopathy were included in this study. Genotype analysis for the two SNPs (− 152G > A and − 165C > T) was assessed by using the PCR–RFLP technique. In addition, the serum protein level of VEGF was measured by ELISA assay.

Results

The results showed a significant relationship between − 152G > A (rs13207351) polymorphism and both proliferative and non-proliferative retinopathy in genotypes (GG, GA, AA). The risk factor increment in the mutant heterozygous genotype (GA) was significantly increased in NPDR compared to PDR (OR = 16.3, 95%CI = 0.80–331.7); (OR = 20.4, 95%CI = 1.08–385.3), respectively. There was no significance between VEGF − 165C > T (rs79469752) gene polymorphism and retinopathy. Moreover, the serum protein level of VEGF showed a highly significant increase (P = 0.0001) in PDR (Mean ± SD = 3691 ± 124.9) when compared to both DWR (Mean ± SD = 497.3 ± 18.51) and NPDR (Mean ± SD = 1674.5 ± 771.7). These results were supported by the increased level of VEGF in serum protein which is positively correlated with the severity of retinopathy. Measuring VEGF protein level in DR patients would help as a biomarker in early diagnosis.

Conclusion

The increase in the mutant heterogeneous GA genotype in VEGF − 152G > A SNP could be a risk factor for the progression of severe retinopathy in diabetic patients.

Genetic Variants and Their Associations to Type 2 Diabetes Mellitus Complications in the United Arab Emirates

Aim

Type 2 Diabetes Mellitus (T2DM) is associated with microvascular complications, including diabetic retinopathy (DR), diabetic nephropathy (DNp), and diabetic peripheral neuropathy (DPN). In this study, we investigated genetic variations and Single Nucleotide Polymorphisms (SNPs) associated with DR, DNp, DPN and their combinations among T2DM patients of Arab origin from the United Arab Emirates, to establish the role of genes in the progression of microvascular diabetes complications.

Methods

A total of 158 Emirati patients with T2DM were recruited in this study. The study population was divided into 8 groups based on the presence of single, dual, or all three complications. SNPs were selected for association analyses through a search of publicly available databases, specifically genome-wide association study (GWAS) catalog, infinome genome interpretation platform, and GWAS Central database. A multivariate logistic regression analysis and association test were performed to evaluate the association between 83 SNPs and DR, DNp, DPN, and their combinations.

Results

Eighty-three SNPs were identified as being associated with T2DM and 18 SNPs had significant associations to one or more diabetes complications. The most strongly significant association for DR was rs3024997 SNP in the VEGFA gene. The top-ranked SNP for DPN was rs4496877 in the NOS3 gene. A trend towards association was detected at rs833068 and rs3024998 in the VEGFA gene with DR and rs743507 and rs1808593 in the NOS3 gene with DNp. For dual complications, the rs833061, rs833068 and rs3024997 in the VEGFA gene and the rs4149263 SNP in the ABCA1 gene were also with borderline association with DR/DNp and DPN/DNp, respectively. Diabetic with all of the complications was significantly associated with rs2230806 in the ABCA1 gene. In addition, the highly associated SNPs rs3024997 of the VEGFA gene and rs4496877 of the NOS3 gene were linked to DR and DPN after adjusting for the effects of other associated markers, respectively.

Conclusions

The present study reports associations of different genetic polymorphisms with microvascular complications and their combinations in Emirati T2DM patients, reporting new associations, and corroborating previous findings. Of interest is that some SNPs/genes were only present if multiple comorbidities were present and not associated with any single complication.

Clinical Implications of MiR128, Angiotensin I Converting Enzyme and Vascular Endothelial Growth Factor Gene Abnormalities and Their Association with T2D

Type 2 DM (T2D) results from the interaction of the genetic and environmental risk factors. Vascular endothelial growth factor (VEGF), angiotensin I-converting enzyme (ACE), and MicroRNAs (MiRNAs) are involved in important physiological processes. Gene variations in VEGF, ACE and MiRNA genes are associated with diseases. In this study we investigated the associations of the VEGF-2578 C/A (rs699947), VEGF-2549 insertion/deletion (I/D), and ACE I/D rs4646994 and Mir128a (rs11888095) gene variations with T2D using the amplification refractory mutation system PCR (ARMS-PCR) and mutation specific PCR (MSP). We screened 122 T2D cases and 126 healthy controls (HCs) for the rs699947, and 133 T2D cases and 133 HCs for the VEGF I/D polymorphism. For the ACE I/D we screened 152 cases and 150 HCs, and we screened 129 cases and 112 HCs for the Mir128a (rs11888095). The results showed that the CA genotype of the VEGF rs699947 and D allele of the VEGF I/D polymorphisms were associated with T2D with OR =2.01, p-value = 0.011, and OR = 2.42, p-value = 0.010, respectively. The result indicated the D allele of the ACE ID was protective against T2D with OR = 0.10, p-value = 0.0001, whereas the TC genotype and the T allele of the Mir128a (rs11888095) were associated with increased risk to T2D with OR = 3.16, p-value = 0.0001, and OR = 1.68, p-value = 0.01, respectively. We conclude that the VEGF (rs699947), VEGF I/D and Mir128a (rs11888095) are potential risk loci for T2D, and that the D allele of the ACE ID polymorphism may be protective against T2D. These results help in identification and stratification for the individuals that at risk for T2D. However, future well-designed studies in different populations and with larger sample sizes are required. Moreover, studies to examine the effects of these polymorphisms on VEGF and ACE proteins are recommended.

Update in the epidemiology, risk factors, screening, and treatment of diabetic retinopathy

Despite progress in the treatment of diabetic macular edema and diabetic retinopathy, the rate of lower fundus examination due to limitations of medical resources delays the diagnosis and treatment of diabetic retinopathy. Therefore, implementation of automated diabetic retinopathy screening program and the identification of more specific and sensitive biomarkers are important for facilitating the earlier detection of diabetic macular edema and diabetic retinopathy to decrease the prevalence of poor vision and blindness.

Genetics of Diabetic Retinopathy, a Leading Cause of Irreversible Blindness in the Industrialized World

Diabetic retinopathy (DR) is a chronic complication of diabetes and a leading cause of blindness in the industrialized world. Traditional risk factors, such as glycemic control and duration of diabetes, are unable to explain why some individuals remain protected while others progress to a more severe form of the disease. Differences are also observed in DR heritability as well as the response to anti-vascular endothelial growth factor (VEGF) treatment. This review discusses various aspects of genetics in DR to shed light on DR pathogenesis and treatment. First, we discuss the global burden of DR followed by a discussion on disease pathogenesis as well as the role genetics plays in the prevalence and progression of DR. Subsequently, we provide a review of studies related to DR’s genetic contribution, such as candidate gene studies, linkage studies, and genome-wide association studies (GWAS) as well as other clinical and meta-analysis studies that have identified putative candidate genes. With the advent of newer cutting-edge technologies, identifying the genetic components in DR has played an important role in understanding DR incidence, progression, and response to treatment, thereby developing newer therapeutic targets and therapies.

Polymorphisms of vascular endothelial growth factor-2578C/A rs699947 are risk factors for diabetic retinopathy in type-2 diabetes mellitus patients in Bali, Indonesia

BACKGROUND

Diabetic retinopathy (DR) is one of the complications in diabetes mellitus (DM) which caused by microvascular-damage in the retina due to long termmetabolic changes in diabetes. To date, there has been much research targeted on the determinant of genetic identification in DR patients. In DR, Vascular Endothelial Growth Factor (VEGF) gene is accountable for breaking down the blood-retinal barrier and implicated in the role of neovascularization. It is thought that the polymorphism of VEGF -2578C/A (rs699947) contributed to the development of diabetic retinopathy in type 2 DM.

AIM

To determine whether the polymorphisms of VEGF-2578C/A are the risk factors for DR in type 2 DM patients in Bali, Indonesia.

METHODS

This study is a case-control model comparing 33 cases DR patients in type-2 diabetes mellitus and 35 cases of non-DR as controls in Balinese ethnic. Polymorphisms of VEGF-2578C/A were examined by PCR analysis and DNA sequencing on rs699947 to identify any variation in A/C/T allele distribution. Chi-square test was used to analyze the data and determine the relation of polymorphism and DR.

RESULTS

This research showed the genetic variation existence in VEGF-2578C/A polymorphism significantly (p = 0,000) with C allele was higher in the DR group, in contrast, A and T allele were greater in the non-DR group compared to DR group. The result showed that C allele in VEGF-2578 contributed as a risk factor (OR = 13.05; 95% CI = 2.69-63.18; p = 0.001) for DR in type-2 DM (T2DM) patients in Bali, Indonesia.

CONCLUSION

Polymorphism of VEGF-2578C/A (rs699947) allele distribution can be concluded as a risk factor of DR within T2DM patients in Bali, Indonesia. This study may also be used to expand the knowledge in managing DR patients at an earlier stage to avoid further complications.

Associations between Vascular Endothelial Growth Factor Gene Polymorphisms and Different Types of Diabetic Retinopathy Susceptibility: A Systematic Review and Meta-Analysis

BACKGROUND

Vascular endothelial growth factor (VEGF) gene polymorphisms have been shown to be associated with the risk of diabetic retinopathy (DR), but the results were inconsistent. The aim of this study was to systematically assess the associations between VEGF gene polymorphisms and different types of DR (nonproliferative DR and proliferative DR).

METHODS

Electronic databases PubMed, Embase, Web of Science, CNKI, and WANFANG DATA were searched for articles on the associations between VEGF gene polymorphisms and different types of DR up to November 6, 2019. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated, and subgroup analyses were conducted by ethnicity. Sensitivity analysis was conducted to assess the stability of the results. Publication bias was assessed by using the Egger regression asymmetry test and visualization of funnel plots. A systematic review was conducted for polymorphisms with a high degree of heterogeneity (I ² > 75%) or studied in only one study.

RESULTS

A total of 13 and 18 studies analyzed the associations between VEGF SNPs and nonproliferative DR (NPDR) as well as proliferative DR (PDR), respectively. There were significant associations between rs2010963 and NPDR in Asian (dominant model: OR = 1.29, 95%CI = 1.04 - 1.60); and rs2010963 is associated with PDR in total population (dominant model: OR = 1.20, 95%CI = 1.03 - 1.41), either Asian (recessive model: OR = 1.57, 95%CI = 1.04 - 2.35) or Caucasian (recessive model: OR = 1.83, 95%CI = 1.28 - 2.63). Rs833061 is associated with PDR in Asian (recessive model: OR = 1.58, 95%CI = 1.11 - 2.26). Rs699947 is associated with NPDR in the total population (dominant model: OR = 2.04, 95%CI = 1.30 - 3.21) and associated with PDR in Asian (dominant model: OR = 1.72, 95%CI = 1.05 - 2.84).

CONCLUSIONS

Rs2010963, rs833061, and rs699947 are associated with NPDR or PDR, which may be involved in the occurrence and development of DR.

Association of VEGF Gene Family Variants with Central Macular Thickness and Visual Acuity after Aflibercept Short-Term Treatment in Diabetic Patients: A Pilot Study

INTRODUCTION

Diabetic retinopathy (DR) is one of the major vision-threatening causes worldwide. Searching for an individualized therapeutic strategy to prevent its progress is challenging.

OBJECTIVE

This work aimed to investigate the association of angiogenesis-inducer vascular endothelial growth factor (VEGF) gene family and related receptor variants (rs833069, rs12366035, rs7664413, rs7993418, and rs2305948) with susceptibility of DR and the response to 1 dose of aflibercept treatment in type 2 diabetes mellitus (T2DM).

METHODS

Consecutive eligible patients with T2DM (n = 125) and 110 unrelated controls were enrolled in this preliminary prospective case-controlled study. Genotyping was identified using TaqMan real-time PCR. Adjusted odds ratio (OR) with 95% confidence interval (CI) was applied to assess the strength of the association with the clinical/ophthalmological characteristics and early response to intravitreal aflibercept treatment in terms of improved visual acuity (BCVA) and central macular thickness (CMT).

RESULTS

We found that both VEGFB rs12366035 and VEGFC rs7664413 conferred higher risk for DR progression under allelic (OR [95% CI]: 1.71 [1.07-2.74]), homozygote comparison (3.55 [1.32-9.57]), and recessive (3.77 [1.43-9.93]) models for the former and under allelic (2.09 [1.25-3.490, homozygote comparison (2.76 [1.02-7.45]), and recessive (2.62 [0.98-6.98] models for the latter. In contrast, VEGFR1 rs7993418 conferred protection against DR under heterozygote comparison and dominant models. The rs12366035*T/T genotype showed the worst pretreatment BCVA score (0.35 ± 0.24) compared to other corresponding genotypes (0.66 ± 0.26 in C/T and 0.54 ± 0.25 in C/C carriers) (p = 0.008). Meanwhile, patients with rs7993418*G/G of VEGFR1 exhibited a significant reduction in CMT after aflibercept injection (12.26 ± 35.43 µ in G/G vs. 3.57 ± 8.74 µ in A/A) (p = 0.037).

CONCLUSIONS

Polymorphisms of the studied VEGF/receptors could be considered as genetic risk factors of DM/DR development and could play an important role in aflibercept early response for DR patients in the study population.

Relationship between Serum Vascular Endothelial Growth Factor Levels and Stages of Diabetic Retinopathy and Other Biomarkers

Aim

This study aims to measure serum vascular endothelial growth factor (VEGF) levels in a sample of Jordanian patients and to determine their relationship with the different stages of diabetic retinopathy. It also explores the correlation between VEGF concentrations and different biochemical and demographic findings.

Materials and Methods

A total of 167 adults participated in the study. Participants were divided into two main categories: patients with diabetes mellitus (DM) type 2 without diabetic retinopathy (DR) (N = 62) and patients with DM type 2 affected by DR (N = 105). DR patients were further subclassified into nonproliferative (N = 41) and proliferative (N = 64). Basic laboratory tests were measured to correlate with VEGF levels. Irisin, a hormone linked to diabetic retinopathy was also measured and correlated with VEGF.

Results

Serum VEGF was found to positively correlate with the severity of diabetic retinopathy. The means of VEGF serum concentrations were 60 pg/mL for controls, 133 pg/mL for nonproliferative DR patients, and 229 pg/mL for proliferative DR patients. We found a significant positive correlation with glycosylated hemoglobin (HbA1c), and a significant negative correlation with high-density lipoprotein (HDL) levels, age, and irisin.

Conclusion

In this cohort of Jordanian diabetics, serum VEGF concentrations strongly correlated with the presence and stages of diabetic retinopathy, suggesting it as an appropriate indicator for diabetic retinopathy early detection and management in this society. VEGF levels also significantly correlated with HbA1c, HDL, and irisin levels. Further studies are encouraged to explore these relationships in other ethnic groups and with different diabetic complications.

Genetics of Diabetic Retinopathy

PURPOSE OF REVIEW

The goal of this paper is to review the latest findings in understanding the genetics of diabetic retinopathy. We highlight recent literature using a variety of molecular genetic techniques to identify variants which contribute to genetic susceptibility for diabetic retinopathy.

RECENT FINDINGS

New genome-wide association study (GWAS) and whole-exome sequencing approaches have been utilized to identify both common and rare variants associated with diabetic retinopathy. While variants have been identified in isolated studies, no variants have been replicated across multiple studies. The identification of genetic factors associated with diabetic retinopathy remains elusive. This is due to the multifactorial nature of the disease, small sample sizes for GWAS, and difficulty in controlling covariates of the disease. Larger populations as well as utilization of new sequencing and data analysis techniques may lead to new insights into genetic factors associated with diabetic retinopathy in the future.

The relationship of the endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF) gene polymorphism in Turkish type 2 diabetic patients with and without diabetic foot ulcers

OBJECTIVE

This study aims to evaluate the influence of eNOS G894T and VEGF C936T gene polymorphism in diabetic foot ulcers.

METHOD

We studied 50 patients with diabetic foot ulcers and 57 diabetic patients without diabetic foot ulcer and a control group of 75 healthy individuals.

RESULTS

The genotype eNOS distribution did not differ between Type 2 Diabetic Patients group and Diabetic Foot Ulcer group (P>0.05). The frequency of the polymorphic T allele in Type 2 Diabetic Patients were significantly higher than the control group (42.3% and 24.5%, respectively)(p<0.01). The frequency of the polymorphic T allele between the Type 2 Diabetic Patients and Diabetic Foot Ulcer group was similar (p>0.05). The genotype VEGF distribution did not differ between Type 2 Diabetic Patients group and Diabetic Foot Ulcer group (P>0.05). The frequency of the polymorphic T allele between the Type 2 Diabetic Patients and Diabetic Foot Ulcer group was similar for both groups (p>0.05).

CONCLUSION

Polymorphism of eNOS G894T is not a risk factor for diabetic foot ulcer formation. T allele is a risk factor for diabetes, but T allele is not a risk factor for diabetic foot ulcer formation. Polymorphism of VEGF C936T and T allele are not risk factors for diabetes occurence and diabetic foot formation.

Multilocus genetic risk score for diabetic retinopathy in the Han Chinese population of Taiwan

The aim of this study is to explore the effect of genetic variation on diabetic retinopathy (DR) risk in a Taiwanese population. The logistic regression model was used to evaluate the relationship between DR status and risk factors, including the conventional parameters and genetic risk score (GRS). Candidate single nucleotide polymorphisms (SNPs) in GRS were selected based on previous reports with a combined P < 10^-4 (genome-wide association) and P < 0.05 (meta-analysis). In total, 58 SNPs in 44 susceptibility loci were selected, and four were used to calculate GRS. After adjustment for age, systolic blood pressure, diabetes duration, and HbA1c, the DR risk was 4.95 times higher for patients in the top GRS third tile than for those in the bottom third tile (95% CI = 2.99-8.18; P < 0.001). The addition of genetic information improved DR prediction, increasing the area under the curve (AUC) from 0.72 to 0.77 (P = 0.0024) and improving the sensitivity of the model such that 40 more subjects were reclassified into DR status. The developed multivariate logistic regression model combining conventional risk factors and the multilocus GRS can predict DR, thus enabling timely treatment to reduce blindness in T2D patients.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

Association of VEGFA variants with altered VEGF secretion and type 2 diabetes: A case-control study

BACKGROUND

Vascular endothelial growth factor (VEGF) contributes to type 2 diabetes (T2DM) pathogenesis, and genetic variations in VEGFA gene were suggested to influence VEGF secretion and T2DM pathogenesis.

AIM

To evaluate the association of specific VEGFA variants with altered VEGF levels, and with T2DM among Tunisians.

SUBJECTS AND METHODS

A retrospective case-control study, performed on 815 T2DM patients, and 805 healthy controls. VEGF levels were measured by ELISA, genotyping of VEGFA variants was done by allelic exclusion method (real-time PCR).

RESULTS

MAF of rs1570360, rs2010963, rs25648, rs833068, rs3025036, and rs3025039 were significantly different between T2DM cases and controls. Increased T2DM risk was associated with rs699947, rs1570360, and rs3025020, while reduced T2DM risk was seen with rs1547651, rs2010963, rs25648, rs3025036, and rs3025039 genotypes, thus assigning T2DM susceptibility and protection, respectively. Reduced VEGF levels were associated with rs833061, rs2010963, and rs3025039 heterozygosity and rs3025036 major allele homozygosity in T2DM cases, while increased VEGF levels were seen in rs833070 homozygous major allele genotype. Both rs699947 and rs1570360 positively, while rs2010963 and rs3025036 negatively correlated with fasting glucose. In addition, rs699947 positively correlated with LDL-cholesterol, and rs3025039 positively correlated with diabetes duration, but negatively with HbA1c and serum triglycerides. Haploview analysis identified Block 1 containing 8 loci, and Block 2 with the remaining 3 loci. Haplotypes ACTGCCGG and AACGGCGA (Block 1) were negatively associated with T2DM, while haplotype CCC was positively and haplotype CGC (Block 2) were negatively associated with T2DM.

CONCLUSION

This study confirms the contribution of altered VEGF secretion, resulting from genetic variation in VEGFA gene into T2DM pathogenesis, hence supporting role for VEGFA as T2DM candidate locus.

Association between the vascular endothelial growth factor single nucleotide polymorphisms and diabetic retinopathy risk: A meta-analysis

BACKGROUND

The aim of the present study was to reveal the relationship between vascular endothelial growth factor (VEGF) single nucleotide polymorphisms (SNPs) and susceptibility to diabetic retinopathy (DR).

METHODS

A literature review was conducted (PubMed, Web of Science, Embase) to identify papers about VEGF SNPs and DR published up to 23 September 2015. The VEGF gene SNPs analyzed with regard to DR susceptibility were rs2010963 (G > C), rs833061 (T > C), rs699947 (C > A), rs3025039 (C > T) and rs1570360 (G > A). Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated, and meta-analyses were performed using fixed or random effects models.

RESULTS

Sixteen studies were included in the meta-analysis. Significant associations between the rs3025039 (C > T) polymorphism and increased DR risk were found in the allele model (T/C; pooled OR 1.60, 95% CI 1.07-2.41, P = 0.02), homozygote model (TT/CC; pooled OR 2.08, 95% CI 1.29-3.35, P = 0.003), heterozygote model (TC/CC; pooled OR 1.68, 95% CI 1.04-2.72, P = 0.04), dominant model (TT+TC/CC; pooled OR 1.72, 95% CI 1.06-2.80, P = 0.03), and recessive model (TT/TC+CC; pooled OR 1.80, 95% CI 1.12-2.90, P = 0.02). For rs833061, a significant association between VEGF SNPs and DR was found only in the allele model (C/T; pooled OR 6.34, 95% CI 2.10-19.14, P = 0.001).

CONCLUSIONS

The rs3025039 and rs833061 SNPs are most likely associated with an increased risk of DR. The T allele in rs3025039 and the C allele in rs833061 are associated with increased DR susceptibility.

Clinical worthlessness of genetic prediction of common forms of diabetes mellitus and related chronic complications: A position statement of the Italian Society of Diabetology

AIM

We are currently facing several attempts aimed at marketing genetic data for predicting multifactorial diseases, among which diabetes mellitus is one of the more prevalent. The present document primarily aims at providing to practicing physicians a summary of available data regarding the role of genetic information in predicting diabetes and its chronic complications.

DATA SYNTHESIS

Firstly, general information about characteristics and performance of risk prediction tools will be presented in order to help clinicians to get acquainted with basic methodological information related to the subject at issue. Then, as far as type 1 diabetes is concerned, available data indicate that genetic information and counseling may be useful only in families with many affected individuals. However, since no disease prevention is possible, the utility of predicting this form of diabetes is at question. In the case of type 2 diabetes, available data really question the utility of adding genetic information on top of well performing, easy available and inexpensive non-genetic markers. Finally, the possibility of using the few available genetic data on diabetic complications for improving our ability to predict them will also be presented and discussed. For cardiovascular complication, the addition of genetic information to models based on clinical features does not translate in a substantial improvement in risk discrimination. For all other diabetic complications genetic information are currently very poor and cannot, therefore, be used for improving risk stratification.

CONCLUSIONS

In all, nowadays the use of genetic testing for predicting diabetes and its chronic complications is definitively of little value in clinical practice.

Evaluation of VEGF gene polymorphisms and proliferative diabetic retinopathy in Mexican population

AIM

To assess if the included vascular endothelial growth factor (VEGF) polymorphisms rs3025035, rs3025021 and rs2010963 are associated to proliferative retinopathy in a Mexican population with type 2 diabetes mellitus (T2DM).

METHODS

A case-control study was conducted in adult individuals with T2DM associated to proliferative retinopathy or non-proliferative retinopathy from Oct. 2014 to Jun. 2015 from the Retina Department of the Asociation to Prevent Blindness in Mexico. The selected patients were adults with a diagnosis of T2DM ≥5y. All subjects had a comprehensive ocular examination and the classification of the retinopathy severity was made considering the Early Treatment Diabetic Retinopathy Study (ETDRS) standardization protocols. Genomic DNA was extracted from whole fresh blood. All samples were genotyped by qPCR for selected VEGF polymorphisms. Hardy-Weinberg equilibrium was calculated by comparing Chi-square values between the expected and the observed values for genotype counts.

RESULTS

In total 142 individuals were enrolled, 71 individuals with T2DM and associated proliferative retinopathy and 71 individuals with non-proliferative retinopathy. One-sided Fisher's exact test was performed for rs3025021 [OR (95% CI)=0.44(0.08-2.2); P=0.25] and rs2010963 [OR (95% CI)=0.63(0.25-1.6); P=0.23]. The minor allelic frequencies obtained were 26% for rs3025021, 10% for rs3025035 and 61% for rs2010963. The pairwise linkage disequilibrium between the three SNP was assessed, and was as follows: rs3025021 vs rs3025035: D'=1.0, r²=0.1043, P≤0.0001; rs3025021 vs rs2010963: D'=0.442, r²=0.0446, P=0.149; rs3025035 vs rs2010963: D'=0.505, r²=0.0214, P=0.142.

CONCLUSION

This is the first analysis involving VEGF polymorphisms and proliferative diabetic retinopathy in a Mexican population. A major finding of the present study is that none of the polymorphisms studied was significantly associated with proliferative retinopathy. Based on these results, we can infer that different populations have different associations for the same polymorphisms.

Allele rs2010963 C of the VEGFA gene is associated with the decreased risk of primary varicose veins in ethnic Russians

Objective To study the association of polymorphisms rs699947, rs2010963, rs3025039 in the VEGFA gene region and rs1870377, rs2305949, rs2071559 in the VEGFR2 gene region with the risk of primary varicose veins in ethnic Russians. Methods Genotypes were determined by real-time PCR allelic discrimination. The case group consisted of 448 patients with primary varicose veins and the control group comprised 609 individuals without a history of chronic venous disease. Association was studied by logistic regression analysis. Results Allele rs2010963 C was associated with the decreased risk of varicose veins (additive model of inheritance: odds ratio = 0.73, 95% confidence interval = 0.59-0.91, P = 0.004). Conclusions Our results provide evidence that polymorphism rs2010963 located in the 5' untranslated region of the VEGFA gene can influence genetic susceptibility to primary varicose veins in Russians. Otherwise, it can be in linkage disequilibrium with another functional single nucleotide polymorphism that can alter the level of vascular endothelial growth factor A protein.

Biomarkers of Diabetic Retinopathy

Diabetic retinopathy (DR), a leading cause of acquired vision loss, is a microvascular complication of diabetes. While traditional risk factors for diabetic retinopathy including longer duration of diabetes, poor blood glucose control, and dyslipidemia are helpful in stratifying patient's risk for developing retinopathy, many patients without these traditional risk factors develop DR; furthermore, there are persons with long diabetes duration who do not develop DR. Thus, identifying biomarkers to predict DR or to determine therapeutic response is important. A biomarker can be defined as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Incorporation of biomarkers into risk stratification of persons with diabetes would likely aid in early diagnosis and guide treatment methods for those with DR or with worsening DR. Systemic biomarkers of DR include serum measures including genomic, proteomic, and metabolomics biomarkers. Ocular biomarkers including tears and vitreous and retinal vascular structural changes have also been studied extensively to prognosticate the risk of DR development. The current studies on biomarkers are limited by the need for larger sample sizes, cross-validation in different populations and ethnic groups, and time-efficient and cost-effective analytical techniques. Future research is important to explore novel DR biomarkers that are non-invasive, rapid, economical, and accurate to help reduce the incidence and progression of DR in people with diabetes.

Situational analysis of services for diabetes and diabetic retinopathy and evaluation of programs for the detection and treatment of diabetic retinopathy in India: Methods for the India 11-city 9-state study

BACKGROUND

Diabetic retinopathy (DR) is a leading cause of visual impairment in India. Available evidence shows that there are more than 60 million persons with diabetes in India and that the number will increase to more than a 100 million by 2030. There is a paucity of data on the perceptions and practices of persons with diabetes and the available infrastructure and uptake of services for DR in India.

OBJECTIVES

Assess perception of care and challenges faced in availing eye care services among persons with diabetics and generate evidence on available human resources, infrastructure, and service utilization for DR in India.

METHODS

The cross-sectional, hospital-based survey was conducted in eleven cities across 9 States in India. In each city, public and private providers of eye-care were identified. Both multispecialty and standalone facilities were included. Specially designed semi-open ended questionnaires were administered to the clients. Semi-structured interviews were administered to the service providers (both diabetic care physicians and eye care teams) and observational checklists were used to record findings of the assessment of facilities conducted by a dedicated team of research staff.

RESULTS

A total of 859 units were included in this study. This included 86 eye care and 73 diabetic care facilities, 376 persons with diabetes interviewed in the eye clinics and 288 persons with diabetes interviewed in the diabetic care facilities.

CONCLUSIONS

The findings will have significant implications for the organization of services for persons with diabetes in India.

The role of pharmacogenetics and advances in gene therapy in the treatment of diabetic retinopathy

Diabetic retinopathy (DR) and its complications such as diabetic macular edema continue to remain a major cause for legal blindness in the developed world. While the introduction of anti-tVEGF agents has significantly improved visual outcomes of patients with DR, unpredictable response, largely due to genetic polymorphisms, appears to be a challenge with this therapy. With advances in identification of various genetic biomarkers, novel therapeutic strategies consisting of gene transfer are being developed and tested for patients with DR. Application of pharmacogenetic principles appears to be a promising futuristic strategy to attenuate diabetes-mediated retinal vasculopathy. In this comprehensive review, data from recent studies in the field of pharmacogenomics for the treatment of DR have been provided.

Novel Genetic Actors of Diabetes-Associated Microvascular Complications: Retinopathy, Kidney Disease and Neuropathy

Both type 1 and type 2 diabetes mellitus can lead to the common microvascular complications of diabetic retinopathy, kidney disease, and neuropathy. Diabetic patients do not universally develop these complications. Long duration of diabetes and poor glycemic control explain a lot of the variability in the development of microvascular complications, but not all. Genetic factors account for some of the remaining variability because of the heritability and familial clustering of these complications. There have been a large number of investigations, including linkage studies, candidate gene studies, and genome-wide association studies, all of which have sought to identify the specific variants that increase susceptibility. For retinopathy, several genome-wide association studies have been performed in small or midsize samples, but no reproducible loci across the studies have been identified. For diabetic kidney disease, genome-wide association studies in larger samples have been performed, and loci for this complication are beginning to emerge. However, validation of the existing discoveries, and further novel discoveries in larger samples is ongoing. The amount of genetic research into diabetic neuropathy has been very limited, and much is dedicated to the understanding of genetic risk factors only. Collaborations that pool samples and aim to detect phenotype classifications more precisely are promising avenues for a better explanation of the genetics of diabetic microvascular complications.

Regulatory SNPs Alter the Gene Expression of Diabetic Retinopathy Associated Secretary Factors

OBJECTIVES

Diabetic retinopathy (DR) is a common microvascular complication in both type I and type II diabetes. Several previous reports indicated the serum centration of some secretary factors were highly associated with DR. Therefore, we hypothesis regulatory SNPs (rSNPs) genotype in secretary factors may alter these gene expression and lead to DR.

METHODS

At first, pyrosequencing were applying to screen the SNPs which present allele frequency different in DR and DNR. Then individual genotyping was processed by Taqman assays in Taiwanese DR and DNR patients. To evaluate the effect of SNP allele on transcriptional activity, we measured promoter activity using luciferase reporter constructs.

RESULTS

We found the frequencies of the CC, CG, and GG genotype of the rs2010963 polymorphism were 15.09%, 47.14%, and 37.74% in DR and 12.90%, 19.35%, and 67.74% in DNR, respectively (p = 0.0205). The prevalence of DR was higher (p = 0.00793) in patients with the CC or CG genotype (62.26% and 32.26% for DR and DNR, respectively) compared with the patients with the GG genotype. To evaluate the effect of rs2010963-C allele on transcriptional activity, we measured promoter activity using luciferase reporter constructs. The rs2010963-C reporter showed 1.6 to 2-fold higher luciferase activity than rs2010963-G in 3 cell lines.

CONCLUSION

Our data proposed rs2010963-C altered the expression level of VEGFA in different tissues. We suggested small increase but long term exposure to VEGFA may lead to DR finally.

The role of NOS2A -954G/C and vascular endothelial growth factor +936C/T polymorphisms in type 2 diabetes mellitus and diabetic nonproliferative retinopathy risk management

Type 2 diabetes mellitus (T2DM) remains one of the major health problems in Europe. Retinopathy is one of the major causes of morbidity in T2DM, strongly influencing the evolution and prognosis of these patients. In the last 2 decades, several studies have been conducted to identify the possible genetic susceptibility factors involved in the pathogenesis of the disease. However, there is little data related to the involvement of vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS) gene polymorphisms in the T2DM Caucasian population. The objective of this study was to identify a possible connection between NOS2A −954G/C (rs2297518) and VEGF +936C/T (rs3025039) polymorphisms and the risk of developing T2DM and nonproliferative diabetic retinopathy in a Caucasian population group. We investigated 200 patients diagnosed with T2DM and 208 controls. Genotypes were determined by multiplex polymerase chain reaction-restriction fragment length polymorphism. Statistical and comparative analyses (Fisher’s exact test) for dominant and recessive models of NOS2A −954G/C and VEGF +936C/T polymorphisms revealed an increased risk of T2DM (χ²=8.14, phi =0.141, P=0.004, odds ratio [OR] =2.795, 95% confidence interval [CI] =1.347–5.801; χ²=18.814, phi =0.215, P<0.001, OR =2.59, 95% CI =1.675–4.006, respectively). Also, comparative analysis for the recessive model (using Pearson’s chi-square test [χ²] and the phi coefficient [phi]) reveals that the variant CC genotype of NOS2A gene is more frequently associated with T2DM without retinopathy (χ²=3.835, phi =−0.138, P=0.05, OR =0.447, 95% CI =0.197–1.015). In conclusion, the results of the study place VEGF +936C/T polymorphisms among the genetic risk factor for T2DM, whereas NOS2A −954G/C polymorphisms act like a protective individual factor for nonproliferative retinopathy.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Update on genetics and diabetic retinopathy

Clinical risk factors for diabetic retinopathy (DR), such as duration of disease and degree of glucose control, do not adequately predict disease progression in individual patients, suggesting the presence of a genetic component. Multiple smaller studies have investigated genotype–phenotype correlations in genes encoding vascular endothelial growth factor, aldose reductase, the receptor for advanced glycation end products, and many others. In general, reported results have been conflicting, due to factors including small sample sizes, variations in study design, differences in clinical end points, and underlying genetic differences between study groups. At this time, there is no confirmed association with any risk allele reported. As we continue to collect data from additional studies, the role of genetics in DR may become more apparent.

Association between a vascular endothelial growth factor gene polymorphism (rs2146323) and diabetic retinopathy: a meta-analysis

Background

Vascular endothelial growth factor (VEGF) is thought to play an important role in the pathogenesis of diabetic retinopathy (DR). Previous studies have associated the VEGF rs2146323 polymorphism with the risk of DR. However, the results of these studies are inconsistent. A meta-analysis was performed to evaluate the association between the VEGF rs2146323 polymorphism and the risk of DR.

Methods

The PubMed, EMBASE, Web of Science and Google Scholar literature databases until March 2015 were searched. The differences in the studies were expressed in the form of an odds ratio (OR) and the corresponding 95 % confidence interval (CI). Heterogeneity among the studies was tested using the I² statistic based on the Q test.

Results

A total of four studies (598 cases and 709 controls) were included in the meta-analysis. A significant association was found involving the rs2146323 polymorphism in the dominant model (CA + AA VS. CC) (OR = 1.38, CI = 1.10–1.72, P = 0.005) and the co-dominant model (CA VS. CC) (OR = 1.37, CI = 1.08–1.74, P = 0.008).

Conclusions

Our meta-analysis confirmed the association between the VEGF rs2146323 polymorphism and the risk of DR.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Biomarkers in Diabetic Retinopathy

There is a global diabetes epidemic correlating with an increase in obesity. This coincidence may lead to a rise in the prevalence of type 2 diabetes. There is also an as yet unexplained increase in the incidence of type 1 diabetes, which is not related to adiposity. Whilst improved diabetes care has substantially improved diabetes outcomes, the disease remains a common cause of working age adult-onset blindness. Diabetic retinopathy is the most frequently occurring complication of diabetes; it is greatly feared by many diabetes patients. There are multiple risk factors and markers for the onset and progression of diabetic retinopathy, yet residual risk remains. Screening for diabetic retinopathy is recommended to facilitate early detection and treatment. Common biomarkers of diabetic retinopathy and its risk in clinical practice today relate to the visualization of the retinal vasculature and measures of glycemia, lipids, blood pressure, body weight, smoking, and pregnancy status. Greater knowledge of novel biomarkers and mediators of diabetic retinopathy, such as those related to inflammation and angiogenesis, has contributed to the development of additional therapeutics, in particular for late-stage retinopathy, including intra-ocular corticosteroids and intravitreal vascular endothelial growth factor inhibitors ('anti-VEGFs') agents. Unfortunately, in spite of a range of treatments (including laser photocoagulation, intraocular steroids, and anti-VEGF agents, and more recently oral fenofibrate, a PPAR-alpha agonist lipid-lowering drug), many patients with diabetic retinopathy do not respond well to current therapeutics. Therefore, more effective treatments for diabetic retinopathy are necessary. New analytical techniques, in particular those related to molecular markers, are accelerating progress in diabetic retinopathy research. Given the increasing incidence and prevalence of diabetes, and the limited capacity of healthcare systems to screen and treat diabetic retinopathy, there is need to reliably identify and triage people with diabetes. Biomarkers may facilitate a better understanding of diabetic retinopathy, and contribute to the development of novel treatments and new clinical strategies to prevent vision loss in people with diabetes. This article reviews key aspects related to biomarker research, and focuses on some specific biomarkers relevant to diabetic retinopathy.

Diabetic retinopathy: variations in patient therapeutic outcomes and pharmacogenomics

Diabetes and its microvascular complications in patients poses a significant challenge and constitutes a major health problem. When it comes to manifestations in the eye, each case of diabetic retinopathy (DR) is unique, in terms of the phenotype, genotype, and, more importantly, the therapeutic response. It is therefore important to identify factors that distinguish one patient from another. Personalized therapy in DR is a new trend aimed at achieving maximum therapeutic response in patients by identifying genotypic and phenotypic factors that may result in less than optimal response to conventional therapy, and consequently, lead to poorer outcome. With advances in the identification of these genetic markers, such as gene polymorphisms and human leucocyte antigen associations, as well as development of drugs that can target their effects, the future of personalized medicine in DR is promising. In this comprehensive review, data from various studies have been analyzed to present what has been achieved in the field of pharmacogenomics thus far. An insight into future research is also provided.

The relationships between type 2 diabetic retinopathy and VEGF-634G/C and VEGF-460C/T polymorphisms in Han Chinese subjects

OBJECTIVE

To investigate how VEGF-634G/C and VEGF-460C/T SNPs are related to diabetic retinopathy (DR) in Han Chinese subjects from the Shijiazhuang region of China.

METHODS

Totally 376 DM cases were divided into non-proliferative diabetic retinopathy (NPDR) group (n=124), proliferative diabetic retinopathy (PDR) group (n=108), and diabetes without retinopathy (DWR) group (n=144). PCR/LDRwas utilised to detect and assess the genotypes and allele distribution frequencies at the VEGF-634G/C and VEGF-460C/T loci in each group.

RESULTS

The differences between NPDR, PDR and DWR groups were not significant in genotypes and allele distribution frequencies at VEGF-634G/C locus (P>0.05). But there were significant differences between NPDR and DWR groups in genotypes (P=0.013) and allele distribution frequencies (P=0.002) at VEGF-460C/T locus, at which CT+CC genotypes were associated with a reduced risk of developing NPDR. There were no significant differences in genotypes (P=0.759) or allele distribution frequencies (P=0.433) at VEGF-460C/T locus between PDR and DWR groups.

CONCLUSIONS

Among Chinese Han individuals with type-2 DM, polymorphism -634G/C of the VEGF gene was not correlated with NPDR or PDR; however, polymorphism-460C/T of the VEGF gene was correlated with NPDR, and C allele was associated with lower NPDR risk than T allele.