Interleukins in lacrimal fluid and diabetic retinopathy

Abstract

The leading role of diabetic retinopathy is considered the main causal factor of decreased visual acuity in the able-bodied and elderly ages determines its clinical relevance, including immunological aspects of pathogenesis to improve the diagnosis and treatment of this ophthalmic pathology. Currently, changes in lacrimal fluid interleukins in elderly patients suffering from diabetic retinopathy have not been sufficiently studied. The aim of our work was to study the content of pro-inflammatory and anti-inflammatory interleukins in lacrimal fluid in elderly patients with diabetic retinopathy.The lacrimal fluid interleukins were analyzed in two clinical groups: the main group was represented by 72 elderly patients with diabetic retinopathy, and the control group included 64 patients of the same age with type 2 diabetes mellitus without diabetic retinopathy. The diagnosis of diabetic retinopathy was assessed from the criteria of Clinical Recommendations “Diabetes mellitus, diabetic retinopathy, diabetic macular edema” issued by the All-Russian Association of Ophthalmologists based on the results of a comprehensive ophthalmological examination. In the lacrimal fluid taken from all patients, the content of various pro- and anti-inflammatory interleukins was studied by solid-phase enzyme immunoassay using R&D Diagnostic Inc. (USA) test systems. Arithmetic average values, their errors, relative risk factors and confidence intervals were calculated, and their significance was evaluated. We have obtained following results: a statistically significant increase of most proinflammatory interleukins was detected in the lacrimal fluid of patients with diabetic retinopathy. In particular, expression of IL-6 was increased to 142.9±7.8 pg/ml among the patients with diabetic retinopathy versus 6.8±0.7 pg/ml in the comparison group, IL-3 was increased to 2.4±0.3 pg/ml versus 0.3±0.05 pg/ml, respectively (p < 0.001). The production of other pro-inflammatory interleukins at the local site has also increased, except of IL-7. However, the concentration of IL-4 and IL-10 was significantly decreased in the patients with diabetic retinopathy, with even higher increase of IL-10 (4.3±0.5 pg/ml versus 11.7±2.3 pg/ml, p < 0.001). The relative risk values were the highest for IL-6 (7.824), at the reliable confidence interval of 7.5388.261; for IL-3 these values comprised 3.269 (CI 3.084-3.721). High relative risk values were also established for IL-8, IL-5 and IL-1α2. The relative risk of developing diabetic retinopathy by almost 2 times was associated with higher contents of IL-8 in the lacrimal fluid (statistically significant confidence interval of 1.728-2.432 (p < 0.01); for IL-5 it was 1.748 (confidence interval of 1.462-2.194 (p < 0.01); for IL-1α2 it comprised 1.718 (confidence interval of 1.524-2.137, p < 0.001). These findings suggest an association of the abovementioned interleukins and development of diabetic retinopathy. The established patterns expand modern views concerning immunopathogenesis of diabetic retinopathy, involving the interleukins of lacrimal fluid.