The relationship of aqueous and serum monocyte chemotactic protein-1 and macrophage migration inhibitory factor level with diabetic retinopathy in type 2 diabetic patients

Abstract

Background Various studies have suggested that inflammatory factors such as leucocytes and macrophages are involved in the occurrence and development of diabetic retinopathy (DR),and many cytokines promote the occurrence of DR.However,the relationship of aqueous and serum monocyte chemotactic protein-1 (MCP-1) and macrophage migration inhibitory factor (MIF) change with DR is unclear.Objective This study was to investigate the effects of MCP-1 and MIF in aqueous and serum during DR development.Methods Eighty patients with type 2 diabetes were enrolled from Beijing Shijitan Hospital.These patients received phacoemulsification or phacoemulsification and vitrectomy from September,2010 to June,2011.Twenty-six cataract patients in the same stage (without diabetes) who underwent phacoemulsification surgery served as controls.According to the clinical stage of the DR,the diabetic patients were classified as the non-DR group (NDR) (20 eyes),non-proliferative DR group (NPDR) (38 eyes) and proliferative DR group (PDR) (22 eyes).Aqueous humour and periphery blood samples were collected during the operation to detect MCP-1 and MIF using enzyme-linked immnunosorbent assay (ELISA).Written informed consent was obtained from each subject before any relevant medical examination.Results The average aqueous MCP-1 levels were(1660.78±562.98),(1463.26± 623.41),(686.76±186.16) and(494.35±148.59) ng/L in the PDR group,NPDR group,NDR group and control group,respectively,showing a significant difference among the 4 groups (F=37.968,P=0.000).No significant differences were found in the aqueous MCP-1 levels between the control group and NDR group (P=0.169),or between the NPDR group and PDR group (P=0.117).However,the aqueous MCP-1 levels were significantly elevated in the PDR group,NPDR group and NDR group compared with the control group (P=0.000).The average aqueous MIF levels were (6.85±1.99),(3.56±0.90),(1.10±0.48) and (0.86 ± 0.46) μg/L,respectively,with significant differences among them (F =144.502,P =0.000).Multiple comparisons between groups were found to be significantly different (P =0.000) according to the LSD-t test,except between the control group and NDR group (P =0.475).A significant positive correlation was seen between the aqueous MCP-1 level and MCP-1 level in all study participants (r =0.564,P =0.000).However,serum levels of MCP-1 and MIF were not statistically significantly different among the 4 groups (F =2.158,P＞0.05;F =0.813,P＞0.05).Conclusions The increase of the aqueous MIF and MCP-1 levels is associated with the progression of diabetic retinopathy.The results suggest that MIF and MCP-1 promote the occurrence of DR. Key words: Diabetic retinopathy; Monocyte chemotactic protein-1 ; Migration inhibitory factor; Aqueous humor