Abstract:  Objective To explore the levels of plasma inflammatory biomarkers: tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), soluble interleukin-2 receptor (IL-2R) and C reactive protein (CRP) in patients with different severity of diabetic retinopathy (DR), and to provide evidence for exploring the role of inflammatory reaction in the pathogenesis of DR. Design  Prospective comparative case sieries. Participants 21 patients with type 2 diabetes mellitus (DM) but without DR (DM without DR group), 17 patients with non-proliferative diabetic retinopathy (NPDR group), 23 patients with proliferative diabetic retinopathy (PDR group), and 23 patients without DM (non DM group) were included. Methods The patient's age, sex and past medical history were recorded. All patients underwent test for visual acuity, intraocular pressure, slit lamp and fundus examination. Venous blood samples were collected and biochemical indicators: hemoglobin(HbA1c), fasting blood glucose (Glu), total cholesterol (TC), low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), triglyceride (TG), homocysteine (Hcy), creatinine (CR) and inflammatory related indicators: TNF-α, IL-2R, IL-8, IL-6, and CRP. Main Outcome Measures Plasma inflammatory biomarker levels. Results There were no significant differences in age, sex, hypertension, history of coronary heart disease and cerebral infarction, TC, LDL, HDL, TC, Hcy and plasma CR among the four groups. HbA1c in PDR group (7.51±2.03%), NPDR group (7.48±1.49%) and DM without DR group (7.09±1.54%) was significantly higher than that in non DM group (5.35±0.54%) (P<0.001). The plasma levels of TNF-α in PDR group and NPDR group were significantly higher than those in non-DM group (10.30±5.35 pg/ml) and DM without DR group (12.63±6.65 pg/ml) (P<0.001). The levels of IL-8 in PDR and NPDR group (157.26±200.16 and 197.45±331.08 pg/ml) were significantly higher than those in non-DM group (30.23±29.41 pg/ml) and DM without DR group (29.70±22.04 pg/ml) (P=0.006). There was no significant difference in the concentrations of IL-2R, IL-6 and CRP among groups. Conclusion The plasma inflammatory factors TNF-α and IL-8 in patients with NPDR and PDR were significantly higher than those in patients without DM and in patient with DM but without DR. Increased plasma TNF-α level is an important risk factor for PDR. There is a significant positive correlation between plasma inflammatory factors and creatinine levels. Systemic hyperinflammation may be a common risk factor for diabetic nephropathy and diabetic retinopathy. (Ophthalmol CHN, 2020, 29: 58-62)

Key words: type 2 diabetes mellitus, diabetic retinopathy, inflammatory factors