Abstract
Purpose: :
Cytokines participate in many fundamental biological processes. Diabetic retinopathy is a sight-threatening, chronic ocular disorder that eventually develops in nearly all patients with diabetes. The purpose of this study was to investigate cytokines in human tears and their changes in patients with diabetic retinopathy.
Methods: :
Type 2 diabetic patients with or without diabetic retinopathy and non-diabetic controls, 15 age and gender matched subjects in each group, were recruited and basal tears were collected using a blunt glass capillary tube. Concentrations of IL-1β, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12 (p70), IL-13, IL-15, IL-17, Eotaxin, FGF-basic, G-CSF, GM-CSF, IFN-γ, IP-10, MCP-1, MIP-1, MIP-1β, RANTES, PDGF bb, VEGF and TNF- were simultaneously evaluated using multiplex bead-based sandwich immunoassay kits. Total protein concentration was also assayed in the samples using Lavapep protein quantitation kits.
Results: :
The major cytokines detected in normal tears are listed below.DIV>The level of all other cytokines was below 200 pg/ml. In comparison with non-diabetic controls, IL-1ra was elevated in diabetics without retinopathy (9641 pg/ml, p<0.05), IP-10 and MCP-1 were elevated in diabetics with retinopathy (14410 and 92 pg/ml respectively, p<0.05) and diabetics without retinopathy (14201 and 91 pg/ml respectively, p<0.05). MCP-1 level in control group was 61 pg/ml. No statistically differences were found between the two diabetic groups (with and without retinopathy) for any of the cytokines. Total protein level was also significantly elevated in diabetic patients.
Conclusions: :
Many cytokines exist in tear fluid with different concentrations. IP-10, MCP-1 and IL-1ra levels are elevated in diabetic tears. The biological relevance of the cytokines in tears and their increase in diabetes remains to be explored.
Keywords: diabetic retinopathy • cytokines/chemokines