To detect the changes of serum complement factors C3 and C4 in diabetic retinopathy (DR) patients, and to explore their role in the occurrence and development of DR.
A cases-controlled study was carried out.Total of 195 patients with DR diagnosed in the First Affiliated Hospital of Harbin Medical University from December 2017 to December 2018 were selected as the DR group, 150 patients with type 2 diabetes were included as the diabetes group, and 281 simple age-related cataract or strabismus patients were collected at the same time and served as control group.Fasting venous blood was collected and serum was isolated.The concentration of C3 and C4 in serum was determined by immunoturbidimetry.The contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined by rate method, and the contents of total cholesterol and triglyceride were determined by enzyme method.Pearson linear correlation analysis was used to evaluate the correlation between serum complement factors and clinical parameters.Stepwise regression analysis was used to evaluate the influencing factors of complement factor C3 and C4 expression.This study adhered to the tenets of the Declaration of Helsinki and was approved by the Ethical Committee Review Board of the First Affiliated Hospital of Harbin Medical University(No.2016-81500711).
The concentration of serum complement factor C3 in the diabetes group was (1 154.0±177.4)mg/L, which was significantly higher than (1 077.3±177.0)mg/L in the DR group and (1 072.0±184.3)mg/L in the control group, the differences were statistically significant (all at P<0.05); The concentration of serum complement factor C4 in the DR group was (287.5±83.5)mg/L, which was significantly higher than (257.5±70.1)mg/L in the diabetes group and (263.7±77.2)mg/L in the control group, the differences were statistically significant (all at P<0.05). The correlation analysis results showed that the expression level of complement factor C3 was weakly positively correlated with total cholesterol and triglyceride in the diabetes and DR groups (diabetes group: r=0.250, P<0.05; r=0.205, P<0.05.DR group: r=0.308, P<0.01; r=0.213, P<0.01); The expression level of complement factor C4 was weakly positively correlated with total cholesterol and triglyceride in the DR group (r=0.235, P=0.002; r=0.247, P=0.001). Multiple regression analysis showed that total cholesterol and triglyceride were the influencing factors of serum C3 and C4 expression in the DR group.
Complement factors may participate in the pathological process of DR and serum complement factors C3 and C4 are affected by serum total cholesterol and triglyceride in DR patients.