Relationship between Angiogenic and Inflammatory Biomarkers and Diabetic Retinopathy

Background: Diabetic retinopathy (DR) is a common complication of diabetes mellitus and a major cause of vision loss in the working age population. Its pathogenesis is poorly understood but may involve low grade chronic inflammation and angiogenesis. The aim of this study was to evaluate the relationship between serum levels of one inflammatory (IL-6) and angiogenic cytokine (VEGF-A) with the presence and severity of DR in type 2 diabetic mellitus patients. Methods: From January to June 2019, we conducted a cross-sectional analytical study on 84 patients out of which 31 developed DR and 53 did not. All patients underwent complete ophthalmological examination and laboratory analysis for IL-6 and VEGF-A with ELISA Technique. We studied the relation of IL-6 and VEGF-A with the presence and severity of DR, HBA1c, the duration of diabetes. Results: The group with DR had statistically significant higher levels of VEGF-A compared to the control group (390.5 pg/ml vs. 173.1 pg/ml; p = 0.007). There was no significant difference in IL-6 levels between both groups (42.8 pg/ml vs. 31.7 pg/ml; p = 0.10). Equally there was no association between these 2 cytokines and macular oedema or with the severity of DR. The level of IL-6 was associated to the balance of diabetes (p = 0.006) although VEGF-A was not (p = 0.15). Moreover, Il-6 (p = 0.31) and VEGF-A (p = 0.24) were not linked to the duration of diabetes. Conclusion: Serum concentrations of VEGF-A have an effect on the development of DR. They correlate with the presence of the disease but IL-6 does not. However, IL-6 was associated to the balance of diabetes. These 2 biomarkers may play a role in the pathophysiology of diabetes and the diabetic retinopathy. Findings on Il-6 and VEGF-A may therefore contribute to the development of the diagnosis tools and caretaking of diabetes and diabetic retinopathy.