Vitreous levels of vascular endothelial growth factor, stromal cell-derived factor-1α, and angiopoietin-like protein 2 in patients with active proliferative diabetic retinopathy

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 role of inflammation in immune system of diabetic retinopathy: Molecular mechanisms, pathogenetic role and therapeutic implications

Diabetic retinopathy is one of the most common complications of diabetes mellitus and the leading cause of low vision and blindness worldwide. Mounting evidence demonstrates that inflammation is a key mechanism driving diabetes-associated retinal disturbance, yet the pathophysiological process and molecular mechanisms of inflammation underlying diabetic retinopathy are not fully understood. Cytokines, chemokines, and adhesion molecules interact with each other to form a complex molecular network that propagates the inflammatory and pathological cascade of diabetic retinopathy. Therefore, it is important to understand and elucidate inflammation-related mechanisms behind diabetic retinopathy progression. Here, we review the current understanding of the pathology and pathogenesis of inflammation in diabetic retinopathy. In addition, we also summarize the relevant clinical trials to further suggest inflammation-targeted therapeutics for prevention and management of diabetic retinopathy.

The Diagnostic Value of Circulating VEGF in Diabetic Retinopathy in Asia: A Systematic Review and Meta-analysis

PURPOSE

Vascular endothelial growth factor (VEGF) has obvious clinical value in diabetes, but the conclusions on the diagnostic value of diabetic retinopathy (DR) are not consistent. This study aims to comprehensively evaluate the accuracy of circulating VEGF in the diagnosis of DR in the Asian population by a method of meta-analysis.

METHODS

PubMed, Cochrane Library, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), and China Wanfang Databases were searched for relevant studies on the diagnostic value of VEGF for DR in Asia up to November 2021. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and areas under the curve (AUC) were calculated by Stata 15.0 software.

RESULTS

After screening, eight eligible studies were enrolled, including 547 patients with DR. The results of the meta-analysis showed that the pooled DOR, sensitivity, specificity, PLR, and NLR were 31.67 (95%CI: 13.55 ~ 74.05), 0.86 (95%CI: 0.74 ~ 0.93), 0.84 (95%CI: 0.80 ~ 0.87), 5.33 (95%CI: 4.09 ~ 6.93), 0.17 (95%CI: 0.09 ~ 0.32), respectively. The AUC was 0.86 (95%CI: 0.82 ~ 0.89).

CONCLUSION

Circulating VEGF has a good diagnostic value in DR in the Asian population, with the potential to be an early diagnostic marker for DR.

Changes in aqueous and vitreous inflammatory cytokine levels in proliferative diabetic retinopathy: a systematic review and meta-analysis

BACKGROUND

Diabetic retinopathy is a major complication of diabetes mellitus, where in its most advanced form ischemic changes lead to the development of retinal neovascularization, termed proliferative diabetic retinopathy (PDR). While the development of PDR is often associated with angiogenic and inflammatory cytokines, studies differ on which cytokines are implicated in disease pathogenesis and on the strength of these associations. We therefore conducted a systematic review and meta-analysis to quantitatively assess the existing body of data on intraocular cytokines as biomarkers in PDR.

METHODS

A comprehensive search of the literature without year limitation was conducted to January 18, 2021, which identified 341 studies assessing vitreous or aqueous cytokine levels in PDR, accounting for 10379 eyes with PDR and 6269 eyes from healthy controls. Effect sizes were calculated as standardized mean differences (SMD) of cytokine concentrations between PDR and control patients.

RESULTS

Concentrations (SMD, 95% confidence interval, and p-value) of aqueous IL-1β, IL-6, IL-8, MCP-1, TNF-α, and VEGF, and vitreous IL-2, IL-4, IL-6, IL-8, angiopoietin-2, eotaxin, erythropoietin, GM-CSF, GRO, HMGB-1, IFN-γ, IGF, IP-10, MCP-1, MIP-1, MMP-9, PDGF-AA, PlGF, sCD40L, SDF-1, sICAM-1, sVEGFR, TIMP, TNF-α, and VEGF were significantly higher in patients with PDR when compared to healthy nondiabetic controls. For all other cytokines no differences, failed sensitivity analyses or insufficient data were found.

CONCLUSIONS

This extensive list of cytokines speaks to the complexity of PDR pathogenesis, and informs future investigations into disease pathogenesis, prognosis, and management.