A case-control study of promoter and 5'UTR VEGF polymorphisms in diabetic retinopathy.

Angiogenesis in diabetic retinopathy (DR) is a multifactorial process regulated by hypoxia-induced growth factors and inflammatory cytokines. In addition to the angiogenic switch, the proteolytic processing and altered synthesis of the extracellular matrix are critical steps in this disease. This study was performed to evaluate the levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 (MMP-2 and MMP-9), angiopoietin-1 and angiopoietin-2 (Ang-1 and Ang-2), vascular endothelial growth factor (VEGF), erythropoietin (EPO) and transforming growth factor-β1 (totalTGFβ1) in the vitreous of diabetic eyes undergoing vitrectomy compared with control eyes operated because of macular hole or pucker. Prospective consecutive controlled observational study performed in the unit of vitreoretinal surgery in Finland during the years 2006-2008. Vitreous samples were collected before the start of the conventional 3-ppp vitrectomy. Vitreous MMP-2 and MMP-9, Ang-1 and Ang-2, VEGF, EPO and TGFβ1 concentrations were measured from 69 patients with Type 1 or 2 diabetes and 40 controls. Comparison of eyes with DR with controls revealed that the mean vitreous concentrations of proMMP-2 (p = 0.0015), totalMMP-2 (p = 0.0011), proMMP-9 (p = 0.00001), totalMMP-9 (p < 0.00001), Ang-2 (p < 0.00001), VEGF (p < 0.00001), EPO (p < 0.00001) and totalTGFβ1 (p = 0.000026) were significantly higher in the former group. A multivariate logistic regression analysis suggested intravitreal Ang-2 concentration being the key marker of PDR (p = 0.00025) (OR = 1507.9). The main new finding is that the intravitreal concentrations of Ang-2 correlated significantly with MMP-9, VEGF, EPO and TGFβ1 levels in diabetic eyes undergoing vitrectomy. Thus, these factors could promote retinal angiogenesis synergistically.

Background Investigations regarding serum and plasma vascular endothelial growth factor (VEGF) levels in patients with diabetic retinopathy (DR) are conflicting. This meta-analysis is aimed at determining whether serum and plasma VEGF levels are associated with DR and its severity in diabetic patients. Methods PubMed and EMBASE were used to search for published studies, and serum and plasma VEGF levels were compared among DR, nonproliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), and nondiabetic retinopathy (NDR) patients. Standardized mean differences (SMD) and 95% confidence interval (CI) were pooled using a random effects model. Results A total of 29 studies comprising 1805 DR (or NPDR or PDR) patients and 1699 NDR patients were included. ELISA was used to evaluate serum or plasma VEGF levels in all except for two studies included in this meta-analysis. Overall, serum VEGF levels were significantly higher in DR patients (SMD: 0.74, 95% CI: 0.44-1.03) than those in NDR patients, while plasma VEGF levels were not in the comparison (SMD: 0.40, 95% CI: −0.13-0.92). Similarly, NPDR (SMD: 0.51, 95% CI: 0.22-0.80) and PDR (SMD: 1.32, 95% CI: 0.79-1.85) patients had higher serum VEGF levels compared with NDR patients, but the difference was not significant in plasma samples (SMD: 0.24, 95% CI: −0.47-0.95; SMD: 0.37, 95% CI: −0.30-1.05). In addition, serum VEGF levels were higher in PDR patients than those in NPDR patients (SMD: 0.87, 95% CI: 0.41-1.33), but plasma VEGF levels were not (SMD: −0.00, 95% CI: −0.31-0.31). The subgroup and metaregression analysis revealed that the study location, study design, and publication year of a study have certain influence on heterogeneity between studies in serum or plasma samples. Conclusions VEGF levels in the serum instead of those in the plasma correlate to the presence and severity of DR in diabetic patients. Further large-scale studies are required to confirm these findings.

Cytokine levels are elevated in the ocular fluid of diabetic patients. It is unclear whether aqueous humor levels of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) are related to the vitreous fluid levels of these substances and to the progression of diabetic retinopathy. Aqueous humor and vitreous fluid samples were obtained during cataract and vitreous surgery from ten eyes of ten patients with diabetic macular edema and 26 eyes of 26 patients with proliferative diabetic retinopathy (PDR). The VEGF and IL-6 levels in aqueous humor, vitreous fluid, and plasma were measured by enzyme-linked immunosorbent assay. VEGF and IL-6 levels in aqueous humor were significantly correlated with those in vitreous fluid (rho=0.793 and rho=0.737, respectively). VEGF levels in aqueous humor and vitreous fluid were significantly correlated with the corresponding IL-6 levels (rho=0.631 and rho=0.687, respectively). The aqueous and vitreous levels of VEGF were significantly correlated with the severity of diabetic retinopathy (rho=0.659 and rho=0.771, respectively). Aqueous and vitreous levels of IL-6 were also significantly correlated with the severity of diabetic retinopathy (rho=0.742 and rho=0.746, respectively). Aqueous and vitreous levels of both VEGF and IL-6 were significantly higher in the patients with active PDR than those in quiescent PDR. Our results suggest that there is a significant relationship between VEGF and IL-6 levels in aqueous humor and in vitreous fluid. Measurement of the aqueous levels of VEGF and IL-6 may be useful to analyze the pathogenesis of diabetic retinopathy and to predict disease activity.

This study aims to determine the relationship between HbA1c level and vascular endothelial growth factor (VEGF) serum levels in diabetic retinopathy (DR) patients. VEGF is a proangiogenic glycoprotein, which increases vascular permeability in DR. This is an analytical cross-sectional study of DR among type 2 diabetes patients using a purposive sampling technique. The study population was grouped into non-proliferative DR (NPDR) and proliferative DR (PDR). HbA1c and VEGF serum levels were assessed by taking the patient's venous blood. A total of 82 subjects were included, in which the mean HbA1c levels were 8.17% ± 1.91%, and the median VEGF levels were 85.78 ng/L (range 38.23-149.43 ng/L). A total of 23 out of 35 NPDR patients were female (65.7%), while 29 out of 47 PDR patients were male (61.7%). Approximately 61.7% of PDR patients had diabetes for more than 10 years, while 62.9% of NPDR patients had diabetes for less than 10 years. The PDR group had a higher mean HbAlc level than the NPDR group, but the difference was not statistically significant (p =0.214). There was absolutely no difference in median VEGF levels between the two groups. Spearman's analysis of correlations found no correlation between HbA1 and VEGF levels in DR, both in the NPDR and PDR groups (Correlation coefficient 0.183 and -0.022, respectively). In patients with diabetic retinopathy, there was no statistically significant association between HbA1c and VEGF serum levels. Poor glycemic control's effects on the advancement of VEGF were not demonstrated in this investigation. A marker of the severity of DR may not be the serum level of VEGF.

Objective To explore the relationship between diabetic retinopathy (DR) and vascular endothelial growth factor (VEGF), interleukin-6 (IL-6) levels in the aqueous humor. Methods Aqueous humor samples were collected from diabetic patients with cataracts or without retinopathy, and aqueous humor samples from non-diabetic patients with cataracts were chosen as controls. The content of VEGF in the aqueous humor was determined by using the ELISA technique. Results The level of VEGF in the aqueous humor samples of diabetic patients without retinopathy (NDR), background diabetic retinopathy (BDR) and proliferative diabetic retinopathy (PDR) were (240.29± 26.14) pg/ml, (292.32± 58.43) pg/ml and (477.65± 90.08) pg/ml respectively. The level of IL-6 in the aqueous humor from NDR, BDR and PDR were (160.81± 33.40) pg/ml, (238.82±62.01) pg/ml and (389.42± 90.08) pg/ml respectively. The levels of VEGF and IL-6 in the aqueous humor from the control group were (140.56± 26.24) pg/ml, (82.74± 21.51) pg/ml respectively. Compared with the control,the level of VEGF and IL-6 in the aqueous humor of diabetic patients increased significantly (P<0.01). The level of VEGF and IL-6 in the aqueous of the NDR, BDR and PDR also increased significantly (P <0.01). The level of VEGF significantly correlated with the level of IL-6 in the aqueous humor (r=0.995, P<0.01). The level of VEGF and IL-6 in the aqueous humor also significantly correlated with the severity and prolongation of DR (r=0.869, P <0.01 ;r=0.865, P <0.01). Conclusions VEGF and IL-6 play active roles in the generation and development of DR, and the level of VEGF in the aqueous humor closely correlates with the level of IL-6 in the aqueous humor of diabetic patients. Key words: Vascular endothelial growth factor; Interleukin-6; Diabetic retinopathy

Background Diabetic retinopathy (DR) is a progressive vision-threatening complication of diabetes mellitus,but its pathogenic mechanism is still unclear. Recent studies showed that it may be associated with the inflammation response of retinal capillary. Cytokines can cause induction of proinflammatory and adhesion molecules and thereby increase monocyte endothelial cell adhesion, which is now accepted as the early key event in the development of DR. Objective The present study was to determine the relationship between the stages of DR and the levels of serum vascular endothelial growth factor (VEGF) , interleukin-2 ( IL-2 ), tumor necrosis factor-alpha (TNF-α) in diabetic patients. Methods This was a pilot case-controlled study. Ninety patients with type 2 diabetes mellitus were included in this clinical trial and 30 healthy individuals were enrolled as controls. The patients were grouped into the non-diabetic retinopathy(NDR) group,background DR group and proliferative DR(PDR) group according to the results from ophthalmoscopic examination and fundus fluorescein angiography(FFA) ,with 30 patients for each group. The levels of serum VEGF,IL-2,TNF-α were assayed by ELISA and compared among the 4 groups.Written informed consent was obtained from each subject before received any related medical examination to this study. Results The mean serum VEGF levels were(217.35±27. 87)ng/L,(298.31±49.26)ng/L,and(341.23±40. 18)ng/L, respectively, and mean serum IL-2 levels were( 12. 12± 1. 57 )ng/L, (16.43 ±2. 26 )ng/L, and (21.36±0. 86) ng/L,respectively and mean serum TNF-α levels were( 11.63±0. 94) ng/L, ( 17. 52±0. 65) ng/L,and(22. 01±0. 87 ) ng/L respectively in the patients with NDR ,background DR and PDR, showing significant differences from healthy controls with( 193.46±37. 39 ) ng/L for serum VEGF, ( 8. 99 ±0. 57 ) ng/L for serum IL-2 and ( 7.31 ±0. 52 ) ng/L for serum TNF-α ( F =126. 38, P＜0. 0 1 ;F =120. 37, P＜0. 01 ;F =99. 84, P＜0. 01 ). The levels of serum VEGF, IL-2, and TNF-α in the patients with the NDR,background DR and PDR were increased significantly. The level of serum VEGF showed the positively significant correlation with serum IL-2 level and TNF-α level ( r =0. 749, P ＜ 0.01 ; r =0. 631,P＜0. 01 ). The serum levels of VEGF, IL-2 and TNF-α showed a significantly positive correlation with the prolongation and severity of DR(r=0. 791 ,P＜0. 01 ;r=0. 665 ,P＜0. 01 ;r=0. 632,P＜0. 01 ). Conclusions VEGF, IL-2 and TNF-α play active roles in the generation and development of diabetic retinopathy, and the level of serum VEGF is closely associated with the levels of serum IL-2 and TNF-α. during the development of DR. Key words: Type 2 diabetes mellitus; Diabetic retinopathy; Vascular endothelial growth factor; Interleukin-2; Tumor necrosis factor-alpha

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.

Objective: To assess the correlations of type 2 diabetic retinopathy (DR) severity with vascular endothelial growth factor (VEGF), IL-6, IL-1β and TNF-α and oxidative stress. Methods: 80 patients with type 2 DR were divided into non-proliferative DR (NPDR) group [NPDR+/diabetic macular edema (DME) − group], NPDR with DME group (NPDR+/DME+ group), proliferative DR (PDR) group (PDR+/DME− group) and PDR with DME group (PDR+/DME+ group) according to non-mydriatic fundus examination and angiography. Another 20 patients without DR and DME were selected as control group (DR−/DME− group). VEGF, inflammatory factors (IL-6, IL-1β and TNF-α) and mal-ondialdehyde (MDA) and superoxide dismutase (SOD) were measured. Changes in hemodynamic parameters were detected by color Doppler ultrasound. Results: Compared with those in control group, the inflammatory factors, VEGF, MDA and SOD were significantly increased in the other four groups of patients with RD, in which inflammatory factors and VEGF level were significantly higher in PDR patients than those in NPDR, and higher in DME patients than patients without DME. However, the hemodynamic parameters showed a significantly decreasing trend (all P &lt; 0.05). A positive correlation of VEGF with inflammatory factors was found in aqueous humor. Conclusion: Inflammatory reactions, oxidative stress and angiogenesis are found in DR patients at early stage and during the disease progression. Combined monitoring of their changes is helpful for the early diagnosis of DR. Meanwhile, anti-inflammation, anti-oxidative stress and reversing of angiogenesis treatment might delay DR progression.

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Aim: The aim of the study was to establish the relationship between levels of vascular endothelial growth factor (VEGF) in blood and severity of diabetic retinopathy (DR). Background: The importance of VEGF in the pathogenesis of DR is evident from numerous studies demonstrating a significant increase in VEGF levels in samples obtained from the eye. However, a correlation between blood levels of VEGF and DR has not been conclusively proven or disproven. In this article, we demonstrate the relationship between blood levels of VEGF and the severity of DR. Materials and Methods: This is a hospital-based descriptive analytic study. The study population consisted of 75 Type 2 diabetic patients attending outpatient department for routine DR screening. After obtaining informed consent, 5 ml of blood was drawn from each patient and estimated for the levels of serum VEGF. The data thus obtained were correlated with the grade of DR. Additional parameters studied were duration of diabetes mellitus (DM), hemoglobin levels, blood urea, serum creatinine, fasting blood sugar (FBS) and random blood sugar (RBS), and hemoglobin A1c (HBA1c) levels. Statistical analysis used in this study was Chi-square test, Student's t-test, independent one sample t-test, and analysis of variance using SPSS software version. 19. Results: Overall mean VEGF levels for the study population of 75 diabetic patients were 577.01 ± 291.13 pg/ml. The average duration of DM in the study population was 7.2 years. The average hemoglobin level in the study population was 11.53 ± 2.00 g/dl. The mean urea levels in mg/dl of the whole population were 35.47 ± 25.80 mg/dl. The mean creatinine levels for the population were 1.42 ± 1.55 mg/dL. The mean RBS levels for the whole population were 228.95 ± 74.499 mg/dL. The mean FBS levels for the 75 patients were 165.87 ± 59.04 mg/dl. The mean HBA1c levels were 9.49 ± 2.37%. Conclusion: Levels of blood VEGF are elevated in diabetic patients regardless of whether they have DR or not. There is no statistically significant relationship between blood levels of VEGF and the severity of DR. Even though severe grades of DR showed more anemia, there is no statistically significant relationship between anemia and DR. The levels of urea and creatinine were elevated in the more severe grade of DR. VEGF, therefore, could present a potential treatment and preventive strategy for not only DR but also DM and its complications in general.

The association between subclinical hypothyroidism (SCH) and microvascular complications of type 2 diabetes is unclear. We examined whether SCH is associated with diabetic retinopathy or nephropathy in Korean patients with type 2 diabetes. Data from 489 patients who visited the diabetes clinic at a university hospital between 2001 and 2007 were analyzed retrospectively. Participants were evaluated for glycemic control, thyroid function, and diabetic retinopathy and nephropathy. Diabetic retinopathy was classified into five grades. Diabetic nephropathy was assessed by the presence of albuminuria. Patients in the SCH group had a higher proportion of women, older age, longer duration of diabetes, higher systolic and diastolic blood pressure, and higher insulin resistance index compared with the euthyroid group. No significant difference in family history of diabetes or body mass index was found between groups. The prevalence of severe diabetic retinopathy (severe nonproliferative diabetic retinopathy or proliferative diabetic retinopathy) was significantly higher in the SCH group than the euthyroid group (32.8% vs. 19.6%, P = 0.036), whereas no between-group difference was found in the prevalence of diabetic nephropathy. After adjustment for potential confounding factors (HbA1c, BMI, duration of diabetes, diabetic nephropathy, and hypertension) by multivariate logistic regression analysis, SCH remained significantly associated with severe diabetic retinopathy (odds ratio 2.086 (95% CI, 1.010-4.307), P = 0.047). These results suggest that SCH was independently associated with severe diabetic retinopathy in patients with type 2 diabetes. Further prospective studies are required to confirm the association between SCH and diabetic retinopathy.

Rapid, bloody, and blinding diabetic retinopathy

Increased levels of cytokines in the aqueous humor correlate with the severity of diabetic retinopathy

Background: Proliferative diabetic retinopathy (PDR) may be a response to abnormal angiogenic growth factors such as vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang-2), and the soluble angiopoietin receptor tie-2. The...

Aqueous Levels of Angiopoietin-like 4 and Semaphorin 3E Correlate with Nonperfusion Area and Macular Volume in Diabetic Retinopathy