Serum Vascular Endothelial Growth Factor Levels Correlate with Severity of Retinopathy in Diabetic Patients: A Systematic Review and Meta-Analysis

Diabetic Retinopathy and Cardiovascular Disease: A Literature Review

Diabetic complications can be divided into macrovascular complications such as cardiovascular disease and cerebrovascular disease and microvascular complications such as diabetic retinopathy, diabetic nephropathy and diabetic neuropathy. Among them, cardiovascular disease (CVD) is an important cause of death in diabetic patients. Diabetes retinopathy (DR) is one of the main reasons for the increasing disability rate of diabetes. In recent years, some studies have found that because DR and CVD have a common pathophysiological basis, the occurrence of DR and CVD are inseparable, and to a certain extent, DR can predict the occurrence of CVD. With the development of technology, the fundus parameters of DR can be quantitatively analyzed as an independent risk factor of CVD. In addition, the cytokines related to DR can also be used for early screening of DR. Although many advances have been made in the treatment of CVD, its situation of prevention and treatment is still not optimistic. This review hopes to discuss the feasibility of DR in predicting CVD from the common pathophysiological mechanism of DR and CVD, the new progress of diagnostic techniques for DR, and the biomarkers for early screening of DR.

Circulating Biomarkers to Predict Diabetic Retinopathy in Patients with Diabetic Kidney Disease

The purpose of this review is to outline the currently available circulating biomarkers to predict diabetic retinopathy (DR) in patients with diabetic kidney disease (DKD). Studies have extensively reported the association between DR and DKD, suggesting the presence of common pathways of microangiopathy. The presence of other ocular complications including diabetic cataracts may hinder the detection of retinopathy, which may affect the visual outcome after surgery. Unlike DKD screening, the detection of DR requires complex, costly machines and trained technicians. Recognizing potential biological markers related to glycation and oxidative stress, inflammation and endothelial dysfunction, basement membrane thickening, angiogenesis, and thrombosis as well as novel molecular markers involved in the microangiopathy process may be useful as predictors of retinopathy and identify those at risk of DR progression, especially in cases where retinal visualization becomes a clinical challenge. Further investigations could assist in deciding which biomarkers possess the highest predictive power to predict retinopathy in clinical settings.

Baseline Diabetic Retinopathy Severity and Time to Diabetic Macular Edema Resolution with Ranibizumab Treatment: A Meta-Analysis

OBJECTIVE

Having a better understanding of how long diabetic macular edema (DME) takes to resolve in patients with diabetic retinopathy (DR) after treatment with ranibizumab, and the factors affecting this outcome, would be of benefit to physicians and patients alike. The objective of this analysis was to evaluate the time to first DME resolution and the impact of baseline DR severity on this outcome in patients treated with ranibizumab in phase III clinical trials.

DESIGN

Meta-analysis of data from the phase III trials, RIDE (NCT00473382) and RISE (NCT00473330), and DR Clinical Research Network protocols I (NCT00444600), S (NCT01489189), and T (NCT01627249).

PARTICIPANTS

Patients with DME (central subfield thickness [CST] > 250 μm) and DR with Diabetic Retinopathy Severity Scale (DRSS) score between 35 and 85.

INTERVENTION

Intravitreal injection of ranibizumab.

MAIN OUTCOME MEASURES

The time to first DME resolution (defined as CST ≤ 250 μm) within 24 months was evaluated overall and by baseline DR severity category per the DRSS (35 of 43 [mild or moderate nonproliferative DR], 47-53 [moderately severe or severe nonproliferative DR], 60 [mild proliferative DR], and 61-85 [moderately severe to severe proliferative DR]).

RESULTS

There were 777 patients included in the meta-analysis. The overall mean (95% confidence interval) time to first DME resolution, adjusted for baseline CST, was 6.0 (5.6-6.4) months. The mean (95% CI) time to first DME resolution was 7.1 (6.2-7.9), 5.9 (5.2-6.6), 6.0 (4.8-7.2), and 4.5 (3.5-5.5) months for the 35 of 43, 47 to 53, 60, and 61 to 85 baseline DRSS categories, respectively (overall P = 0.002). By month 24, the proportion of eyes with DME resolution was 74.9% (221 of 295), 77.5% (299 of 386), 69.4% (109 of 157), and 78.7% (148 of 188) for the 35 of 43, 47 to 53, 60, and 61 to 85 baseline DRSS categories, respectively (overall P = 0.17).

CONCLUSIONS

This meta-analysis of data from patients treated with ranibizumab showed that DME resolution was faster in patients with more severe DR at baseline. However, by month 24, a similar proportion of patients achieved DME resolution, regardless of baseline DR severity. These findings may guide treatment decisions and inform patient expectations in clinical practice.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Circulatory Biomarkers and Diabetic Retinopathy in Racial and Ethnic Populations

Clinical staging systems for diagnosis and treatment of diabetic retinopathy (DR) must closely relate to endpoints that are both relevant for patients and feasible for physicians to implement. Current DR staging systems for clinical eye care and research provide detailed phenotypic characterization to predict patient outcomes in diabetes but have limitations. Biochemical biomarkers provide a rich pool of potential candidates for new DR staging systems that can be readily measured in accessible fluids. Circulating biomarkers that are specific to the retina and relate to angiogenesis and inflammation have been suggested as relevant for DR. Although there is a lack of multi-ethnic studies evaluating circulatory biomarkers in DR, variability in circulatory biomarkers have been reported in people from different ethnic and racial backgrounds. Therefore, there is a need for future studies to evaluate individual or combinations of biomarkers in diverse populations with DR from different ethnic and racial backgrounds.

Serum and vitreous vascular endothelial growth factor levels in diabetic retinopathy

PURPOSE

To research whether serum vascular endothelial growth factor (VEGF) levels could be used to evaluate diabetic retinopathy (DR) progression and to compare vitreous VEGF levels after injections of intravitreal bevacizumab (IVB), ranibizumab (IVR), and triamcinolone acetonide (IVTA) in proliferative diabetic retinopathy (PDR).

METHODS

We enrolled a total of 91 eyes of 89 subjects (70 eyes of 68 diabetics and 21 eyes of 21 non-diabetic controls). The diabetic subjects were divided into three groups as PDR (n = 28), non-proliferative diabetic retinopathy (n = 20), and no-DR (n = 20). Eyes with PDR (n = 31) were injected with IVB (n = 7), IVR (n = 10), or IVTA (n = 6) 3 days before vitrectomy, and eight eyes did not receive an injection. Serum and vitreous samples were collected before vitrectomy and analyzed using ELISA.

RESULTS

We found the severity of retinopathy was not correlated with serum VEGF levels (P = .919, ρ = -0.011). Compared with the controls, vitreous VEGF was higher in the PDR (P < .001), whereas serum VEGF did not differ (P = .99). The controls had lower vitreous VEGF than the IVB, IVR, and no-injection subgroups (P = .01, P < .001, and P = .04, respectively). Vitreous VEGF was similar among the injected and no-injection subgroups (P = .17).

CONCLUSIONS

Serum VEGF levels may not directly reflect retinopathy progression. Neither IVB, IVR nor IVTA could eliminate vitreous VEGF levels within 3 days before vitrectomy.

The effects of vitamin E on non-proliferative diabetic retinopathy in type 2 diabetes mellitus: Are they sustainable with 12 months of therapy

Introduction:

Prolonged uncontrolled hyperglycaemia has shown to cause oxidative stress, inflammation, thrombosis and upregulation of angiogenesis in diabetics, which all contributes to diabetic retinopathy development and progression. Vitamin E is found to have anti-inflammatory, anti-oxidative, anti-thrombogenic and anti-angiogenesis which could play an important role in early treatment of diabetic retinopathy. This study aims to investigate the effect of Tocotrienol-rich vitamin E (Tocovid) on the progression of retinal microhaemorrhages and diabetic macular oedema in patients with diabetic retinopathy.

Method:

This is a multi-centred, randomized, double-blinded, placebo-controlled trial which involved 55 eligible participants. The participants in the treatment group (n = 22) received Tocovid 200 mg twice daily while those in the placebo group (n = 23) would receive placebo twice daily. Both groups will be on the treatment for a total duration of 12 months. Both retinal signs will be assessed at baseline, 2 months, 6 months and 12 months of treatment to determine the progression of diabetic retinopathy. Serum vascular endothelial growth factor which reflects on the angiogenesis process in the eye was analysed as well at similar time points as the retinal findings.

Results:

After 12 months of treatment, the placebo group had a significant increase of 23.42% in retinal microhaemorrhages (p < 0.05), but the Tocovid group had no significant changes. Moreover, the Tocovid group showed a significant decrease of 48.38% in area of diabetic macular oedema over the 12 months period (p < 0.05), but the placebo group had no significant changes. Meanwhile, there was no significant difference in serum vascular endothelial growth factor level when comparing between both groups.

Conclusion:

These findings could indicate that Tocovid has an important role in preventing early diabetic retinopathy progression.

Diagnostic circulating biomarkers to detect vision-threatening diabetic retinopathy: Potential screening tool of the future?

With the increasing prevalence of diabetes in developing and developed countries, the socio-economic burden of diabetic retinopathy (DR), the leading complication of diabetes, is growing. Diabetic retinopathy (DR) is currently one of the leading causes of blindness in working-age adults worldwide. Robust methodologies exist to detect and monitor DR; however, these rely on specialist imaging techniques and qualified practitioners. This makes detecting and monitoring DR expensive and time-consuming, which is particularly problematic in developing countries where many patients will be remote and have little contact with specialist medical centres. Diabetic retinopathy (DR) is largely asymptomatic until late in the pathology. Therefore, early identification and stratification of vision-threatening DR (VTDR) is highly desirable and will ameliorate the global impact of this disease. A simple, reliable and more cost-effective test would greatly assist in decreasing the burden of DR around the world. Here, we evaluate and review data on circulating protein biomarkers, which have been verified in the context of DR. We also discuss the challenges and developments necessary to translate these promising data into clinically useful assays, to detect VTDR, and their potential integration into simple point-of-care testing devices.

Safety and outcomes of intravitreal aflibercept in diabetic macular edema - a systematic review

BACKGROUND

Recent evidence on the role of vascular endothelial growth factor (VEGF) in the pathogenesis of ischemia and microvascular hyperpermeability leading to macular edema has brought anti-VEGF intravitreal therapy into the limelight.

OBJECTIVE

We performed a systematic literature review focusing on the outcomes and safety of the intravitreal use of aflibercept in diabetic macular edema.

METHODS

The studies documented cases with at least three consecutive intravitreal injections of aflibercept (IVA) repeated monthly with a follow-up period of at least one year. The outcomes were evaluated in terms of reported functional and anatomical improvement of the macula, as reflected by changes in visual acuity and macular thickness measured by Optical Coherence Tomography (OCT). In addition, for safety assessment, all reported local and general adverse effects were analyzed.

RESULTS

All studies showed an overall significant anatomical and functional improvement. In patients with the 5 IVA monthly at the beginning of the therapy, the visual gain at 52 weeks varied widely between 5 and 18.9 EDRS letters, with a mean value of 9.48 letters. The higher gain was obtained in treatment naïve patients, with worse VA and increased CST at baseline. The lower gain was obtained in patients previously treated with anti-VEGF. Anti-Platelet Trialists' Collaboration-defined arterial thromboembolic events were not statistically different between the aflibercept group and the laser group.

CONCLUSIONS

Intravitreal aflibercept therapy provides significant improvement in visual acuity and a good safety profile. Randomized studies are needed to document the optimal frequency of intravitreal injections for optimal treatment.

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.

In vivo fluorescence molecular imaging of the vascular endothelial growth factor in rats with early diabetic retinopathy

Anti-vascular endothelial growth factor (anti-VEGF) therapy is effective for reducing the severity level of diabetic retinopathy (DR). However, it is difficult to determine the in vivo spatial and temporal expression of VEGF in the DR retina at an early stage. Here, we report a quantitatively fluorescence molecular imaging and image analysis method by creating a VEGF targeted fluorescence imaging probe, which can potentially detect and predict anti-VEGF treatment response. Moreover, the ex vivo multiscale fluorescence imaging demonstrated the spatial correlation between VEGF relative expression and vascular abnormalities in two and three dimensions. It revealed that VEGF was mainly abnormally expressed at the bifurcation of the microvessels, which advances the knowledge of the DR progression by molecular fluorescence imaging. Our study has the potential to achieve early detection of DR disease, provide more insight into understanding anti-VEGF treatment, and may help stratify patients based on the molecular imaging of retinal VEGF.

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.

Increased serum concentration of netrin-1 after intravitreal bevacizumab injection: is it a compensatory mechanism to counteract drug side effects?

BACKGROUND

To evaluate alterations in the serum concentrations of vascular endothelial growth factor (VEGF) and netrin-1 after intravitreal bevacizumab (BCZ) injection for the treatment of diabetic macular edema (DME).

METHODS

This prospective case-control study included a total of 50 participants assigned to one of three groups, including 10 individuals with DME and non-proliferative diabetic retinopathy (NPDR), 13 with DME, and proliferative diabetic retinopathy (PDR), and 27 healthy individuals as a control group. Serum VEGF and netrin-1 concentrations were measured by enzyme-linked immunosorbent assays (ELISAs) immediately before, as well as 1 week and 1 month after, intravitreal BCZ injection.

RESULTS

The mean VEGF serum concentrations in the PDR and NPDR groups were 388.4 and 196.9 pg/mL at baseline, respectively. After 1 week, these concentrations changed to 193.41 and 150.23 pg/mL, respectively (P = 0.001 and P = 0.005, respectively); after 1 month, the concentrations were 97.89 and 76.46 pg/mL, respectively (P = 0.001 and P = 0.009, respectively). The mean netrin-1 serum concentrations in the PDR patients and NPDR groups were 318.2 and 252.7 pg/mL at baseline, respectively. After 1 week, these concentrations increased to 476.6 and 416.3 pg/mL, respectively (P = 0.033 and P = 0.005, respectively), and after 1 month, they were 676.6 and 747.5 pg/mL, respectively (P = 0.001 and P = 0.005, respectively). The correlation analysis revealed a significant inverse relationship between changes in serum VEGF and netrin-1 concentrations in both the PDR and NPDR groups (r = - 0.685, P = 0.029).

CONCLUSIONS

Intravitreal BCZ injections work systemically to significantly decrease serum VEGF levels, leading to a significant upregulation in the concentration of another angiogenic mediator, netrin-1.

A 60% Edible Ethanolic Extract of Ulmus davidiana Inhibits Vascular Endothelial Growth Factor-Induced Angiogenesis

As abnormal angiogenesis is associated with exacerbation of various diseases, precise control over angiogenesis is imperative. Vascular endothelial growth factor (VEGF), the most well-known angiogenic factor, binds to VEGF receptor (VEGFR), activates various signaling pathways, and mediates angiogenesis. Therefore, blocking the VEGF-induced angiogenic response-related signaling pathways may alleviate various disease symptoms through inhibition of angiogenesis. Ulmus davidiana is a safe natural product that has been traditionally consumed, but its effects on endothelial cells (ECs) and the underlying mechanism of action are unclear. In the present study, we focused on the effect of a 60% edible ethanolic extract of U. davidiana (U60E) on angiogenesis. U60E inhibited the VEGF-mediated proliferation, tube formation, and migration ability of ECs. Mechanistically, U60E inhibited endothelial nitric oxide synthase activation and nitric oxide production by blocking the protein kinase B signaling pathway activated by VEGF and consequently inhibiting proliferation, tube formation, and migration of ECs. These results suggest that U60E could be a potential and safe therapeutic agent capable of suppressing proangiogenic diseases by inhibiting VEGF-induced angiogenesis.

ASSOCIATION OF SERUM VASOGENIC AND PROINFLAMMATORY FACTORS WITH CLINICAL RESPONSE TO ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR FOR DIABETIC MACULAR EDEMA

PURPOSE

To study the role of serum biomarkers as prognostic factors for qualitative and quantitative response to anti-vascular endothelial growth factor injections for diabetic macular edema (DME).

METHODS

Sixty-seven eyes with DME were treated with intravitreal bevacizumab during a 12-month follow-up period. All cases underwent a baseline workup consisting of 12 inflammatory, metabolic and prothrombotic factors. The following outcomes were evaluated at 3-month intervals until 1 year of follow-up: visual acuity, central subfield thickness (CST), macular volume (MV), % of change from baseline in CST, occurrence of a CST change < 10%, a CST change >20%, and a CST <330 µm, achieving an improvement ≥2 lines of visual acuity, achieving visual acuity ≥20/40.

RESULTS

A significant improvement in CST and visual acuity was seen from third month onwards. Twenty-eight (48.1%) cases were classified as "early responders," 24 (35.8%) as "late responders", and 15 (22.4%) as "poor responders." Serum vascular endothelial growth factor-A levels were significantly lower in "poor responders" (P = 0.006). C-reactive protein (hsCRP) was associated with a limited anatomic response (<10% CST change) (P = 0.002, OR = 1.845, cutoff value of hsCRP = 1.84 mg/L). hsCRP was also negatively associated with obtaining a final CST <330 µm (P = 0.04, r2 = 0.112, OR = 0.643). Baseline visual acuity was significantly associated with 12th month visual acuity (P < 0.001, r2 = 0.602) and also with an improvement ≥2 visual acuity lines (P = 0.009, OR = 20.54).

CONCLUSION

Increased high-sensitivity C-reactive protein was associated with limited anatomic response to anti-vascular endothelial growth factor treatment and persistent DME. Poor responders had significantly lower values of serum vascular endothelial growth factor-A, suggesting an alternative pathogenic pathway for persisting DME.

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.

Effect of glycemic control and dyslipidemia on plasma vascular endothelial growth factor and pigment epithelium-derived factor in diabetic retinopathy patients in Northern Nigeria

OBJECTIVES

The disruption of the reciprocal regulation between vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) has been associated with the pathogenesis of diabetic retinopathy (DR). This study assessed the levels of VEGF, PEDF, indices of glycemia, and lipid profile in diabetic patients with retinopathy.

METHODS

One hundred fifty participants comprised 50 type 2 diabetic patients with DR, 50 without DR and 50 non-diabetic normotensive controls, aged 30-80 years, were randomly recruited for this case-control study. The study was carried out from November 2017 to December 2018. VEGF, PEDF, glycated hemoglobin (HbA1c), fasting plasma glucose, and lipid profile were determined using standard methods. Blood pressures (BP) and anthropometric indices were measured. Chi-squared test of independence, analysis of variance, and Pearson's correlation were used to analyze data. Statistical significance was set at P < 0.05 and 95% confidence interval.

RESULTS

Both diabetic groups had significantly higher (P = 0.001) systolic and diastolic BP, VEGF, PEDF, HbA1c, fasting plasma glucose, triglycerides, total, high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C) levels and significantly lower (P = 0.005) VEGF/PEDF than the controls. However, the diabetics with retinopathy had significantly higher (P = 0.001) HDL-C, LDL-C, VEGF, and PEDF levels compared to the diabetics without retinopathy. There were no significant differences (P > 0.05) in the levels of VEGF, PEDF, and VEGF/PEDF in both groups of diabetics that had good glycemic control and poor glycemic control. There was also no significant difference (P > 0.05) in the levels of VEGF and PEDF between the dyslipidemic and non-dyslipidemic subjects in both diabetic groups.

CONCLUSION

DR is associated with higher levels of VEGF and PEDF while good glycemic control and dyslipidemia seem not to have a profound effect on VEGF and PEDF levels in diabetics with or without DR. Higher PEDF levels are associated with higher atherogenic risk in the diabetics with retinopathy.

Effect of Age and Acute Exercise on Circulating Angioregulatory Factors

The balance of angiogenic factors, including vascular endothelial growth factor (VEGF), and angiostatic factors, like thrombospondin-1 (TSP-1) and endostatin, controls striated muscle angiogenic responses to exercise training. The effect of age on circulating levels of these factors following a bout of exercise is unclear. The authors hypothesized that older adults would have lower circulating VEGF but higher TSP-1 and endostatin after exercise compared with young adults. Ten young and nine older participants cycled for 45 min at 60% estimated HRmax. Serum [VEGF], [TSP-1], and [endostatin] obtained before (PREX), immediately after (POSTX0), and 3 hr after (POSTX3) exercise were analyzed. [VEGF] increased in older adults only from PREX to POSTX0 (p < .05). [TSP-1] increased in both age groups (p < .05). There was no effect of age or exercise on [endostatin]. In conclusion, immediately after exercise, both groups had a similar increase in [TSP-1], but [VEGF] increased in older adults only.

Increased vitreal levels of interleukin-10 in diabetic retinopathy: a Meta-analysis

AIM

To conduct a Meta-analysis for the change of interleukin-10 (IL-10) concentration in vitreous samples of patients with diabetic retinopathy (DR).

METHODS

Systemic search for literature was conducted from the databases of PubMed, Web of Science and Cochrane Library by August 2019. Statistical analyses including standard mean difference (SMD) and its 95% confidence interval (CI) were performed by using RevMan 5.3 software.

RESULTS

Totally 194 studies were screened and finally 11 studies were included in the Meta-analysis. The concentration of IL-10 in the DR group was higher than in the control group (P=0.003, SMD: 0.77, 95%CI: 0.25-1.28). Significant heterogeneity was found among all studies (P<0.00001, I ²=92%). The subgroup analysis showed that the concentration of IL-10 increased in vitreous samples from patients with DR compared to the non-DR controls (P=0.004, SMD: 1.44, 95%CI: 0.46-2.42). Moreover, the concentration of IL-10 in samples of proliferative diabetic retinopathy (PDR) patients was significantly higher than that of non-proliferative diabetic retinopathy (NPDR) patients (P=0.01, SMD: 0.61, 95%CI: 0.13-1.08).

CONCLUSION

The vitreal concentration of IL-10 is significantly increased in patients with DR. Further studies are needed to reveal the mechanisms of IL-10 in DR.

Relationship between Proliferative Diabetic Retinopathy and Inflammatory Markers in Patients with Type 1 Diabetes in Brazil: A Nested Case Control Study

INTRODUCTION

This study examined the relationship between proliferative diabetic retinopathy (PDR) and serum levels of C-reactive protein, VEGF, TNF-α, and IL-6 inflammatory biomarkers, related to the pathophysiology of diabetic retinopathy.

METHODS

This cross-sectional, case control study comprised 240 patients with type 1 diabetes (80 cases with PDR and 160 controls without diabetic retinopathy) who were matched for gender and duration of diabetes.

RESULTS

C-reactive protein was the only inflammatory biomarker that was positively related to PDR (OR 1.96; 95% CI 1.01-3.78, p = 0.0045). We also noted an association between high glycated hemoglobin levels, the use of angiotensin-converting enzyme inhibitor, low glomerular filtration rate, and PDR.

CONCLUSION

Patients with higher levels of C-reactive protein are more likely to present with PDR. We did not find a link between serum levels of VEGF, TNF-α, or IL-6 and PDR. The function of inflammatory biomarkers in PDR must be addressed in further studies.

VEGF, apelin and HO-1 in diabetic patients with retinopathy: a correlation analysis

BACKGROUND

It's necessary to analyze the role of VEGF, apelin, and HO-1 in patients with type 2 diabetes (T2DM), and to evaluate its relevance to diabetic retinopathy (DR).

METHODS

T2DM patients who were treated in our hospital from December 1, 2018 to November 30, 2019 were included. T2DM patients were divided into non-DR (NDR) group, non-proliferative DR (NPDR) group, and proliferative DR (PDR) group. and healthy participants were selected as the control group. The value of VEGF, apelin, and HO1 in predicting PDR were analyzed by receiver operating characteristic (ROC) curve, and the relations of VEGF, apelin, HO-1 and clinical factors in PDR patients were analyzed by Pearson correlation analysis.

RESULTS

A total of 295 participants were included. The level of FPG and HbAlc in PDR group were significantly higher than that of other groups (all p < 0.05); the level of VEGF and apelin in PDR group were significantly higher than that of other groups (all p < 0.05), but the level of HO-1 in PDR group were significantly less than that of other groups(p = 0.017); the AUC of VEGF, apelin, HO-1 and combined use was 0.806(95%CI: 0.779-0.861), 0.819(95%CI: 0.765-0.878), 0.808(95%CI: 0.733-0.869) and 0.902(95%CI: 0.822-0.958) respectively, the AUC, sensitivity, specificity of the three combined use was significantly higher than that of single VEGF, apelin, HO-1 use(all p < 0.05). The cutoff values of serum VEGF, apelin, and HO-1 levels for predicting PDR were 163.85 pg/ml, 8.27 ng/ml, and 26.06 mmol/L respectively. Serum VEGF, apelin, and HO-1 in patients with PDR was related to the time course of DM, FPG and HbAlc (all p < 0.05).

CONCLUSIONS

VEGF, apelin and HO-1 are related to the progress of DR, and the combined use of VEGF, apelin and HO-1 is beneficial to the diagnosis and treatment of PDR.

Inflammatory and angiogenic biomarkers in diabetic retinopathy

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus (DM) and a leading cause of blindness in working-age adults in developed countries. Numerous investigations have recognised inflammation and angiogenesis as important factors in the development of this complication of diabetes. Current methods of DR treatment are predominantly used at advanced stages of the disease and could be associated with serious side effects. Therefore, new diagnostic methods are needed in order to identify the initial stages of DR as well as monitoring the effects of applied therapy. Biochemical biomarkers are molecules found in blood or other biological fluid and tissue that indicate the existence of an abnormal condition or disease. They could be a valuable tool in detecting early stages of DR, identifying patients most susceptible to retinopathy progression and monitoring treatment outcomes. Biomarkers related to DR can be measured in the blood, retina, vitreous, aqueous humour and recently in tears. As the retina represents a small part of total body mass, a circulating biomarker for DR needs to be highly specific. Local biomarkers are more reliable as indicators of the retinal pathology; however, obtaining a sample of aqueous humour, vitreous or retina is an invasive procedure with potential serious complications. As a non-invasive novel method, tear analysis offers a promising direction in further research for DR biomarker detection. The aim of this paper is to review systemic and local inflammatory and angiogenic biomarkers relevant to this sight threatening diabetic complication.

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.

Potential therapeutic effects of endothelial cells trans-differentiated from Wharton's Jelly-derived mesenchymal stem cells on altered vascular functions in aged diabetic rat model

BACKGROUND

Diabetes mellitus in elderly represents an exceptional subset in the population vulnerable to cardiovascular events. As aging, diabetes mellitus and hypertension share common pathways, an ideal treatment should possess the ability to counter more than one of, if not all, the underlying mechanisms. Stem cells emerged as a potential approach for complicated medical problems. We tested here the possible role of trans-differentiated endothelial cells (ECs) in the treatment of diabetes mellitus in old rats.

METHODS

Mesenchymal stem cells where isolated from umbilical cord Wharton's Jelly and induced to differentiate into endothelial like-cells using vascular endothelial growth factor-enriched media. Thirty aged male Wistar albino rats were used in the present study. Rats were divided (10/group) into: control group (18-20 months old, weighing 350-400 g, received single intraperitoneal injection as well as single intravenous injection via tail vein of the vehicles), aged diabetic group (18-20 months old, weighing 350-400 g, received single intraperitoneal injection of 50 mg/kg streptozotocin, and also received single intravenous injection of saline via tail vein), and aged diabetic + ECs group (18-20 months old, weighing 350-400 g, received single intraperitoneal injection of 50 mg/kg streptozotocin, and also received single intravenous injection of 2*10⁶ MSC-derived ECs in 0.5 ml saline via tail vein) groups. Assessment of SBP, aortic PWV, and renal artery resistance was performed. Serum levels of ET1, ANG II, IL-6, TNF-α, MDA, ROS, and VEGF were evaluated, as well as the aortic NO tissue level and eNOS gene expression. Histopathological and immunostaining assessments of small and large vessels were also performed.

RESULTS

Induction of diabetes in old rats resulted in significant increase in SBP, aortic PWV, renal artery resistance, and serum levels of ET1, ANG II, IL-6, TNF-α, MDA, ROS, and VEGF. While there was significant decrease in aortic NO tissue level and eNOS gene expression in the aged diabetic group when compared to aged control group. ECs treatment resulted in significant improvement of endothelial dysfunction, inflammation and oxidative stress.

CONCLUSION

We report here the potential therapeutic role of trans-differentiated ECs in aged diabetics. ECs demonstrated anti-inflammatory, antioxidant, gene modifying properties, significantly countered endothelial dysfunction, and improved vascular insult.

Glechomanamides A-C, Germacrane Sesquiterpenoids with an Unusual Δ8-7,12-Lactam Moiety from Salvia scapiformis and Their Antiangiogenic Activity

Three new germacrane sesquiterpenoid-type alkaloids with an unusual Δ⁸-7,12-lactam moiety, glechomanamides A-C (1-3), and two pairs of 7,12-hemiketal sesquiterpenoid epimers (4a/b, 5a/b) were isolated from Salvia scapiformis. Their structures were elucidated by spectroscopic methods including HRESIMS, IR, UV, and 1D and 2D NMR and also confirmed by single-crystal X-ray diffraction analysis. The chemical transformation of compounds 1-5 in a solution environment was analyzed by 2D NMR spectroscopy. The aza acetallactams (1-3) were stable in organic solvent, while single crystals of the hemiacetal esters (4a/b, 5a/b) underwent a tautomeric equilibrium after being dissolved. Single crystals of 4a, 4b, and 5a were obtained for the first time as their naturally occurring forms. Glechomanamide B (2) exhibited antiangiogenic activity by suppression of vascular endothelial growth factor (VEGF)-induced tube formation through modulation of VEGF receptor 2 (VEGFR2)-mediated signaling pathways in human umbilical vascular endothelial cells (HUVECs). In addition, compound 2 also showed the significant suppression of mRNA expression associated with glycolysis and angiogenesis biomarkers in high glucose (30 mM)-induced HUVECs. These findings suggest that compound 2 might be a potential lead compound candidate for the management of diabetic retinopathy.