Association of IL-6 Gene (-174 and -572 G/C) Polymorphisms with Proliferative Diabetic Retinopathy of Type 2 Diabetes in a Chinese Population

Abstract

Purpose: To investigate the association of interleukin (IL)-6 with proliferative diabetic retinopathy (PDR) of type 2 diabetes (T2D) in a Chinese population. Methods: Two subtypes of the IL-6 promoter (-174 and -572 G/C) were genotyped in 215 T2D patients with PDR and 207 T2D patients with a normal retinal function (controls) using the PCR-RFLP method. The mRNA and protein expression of IL-6 was examined by real-time PCR. Results: T2D patients with PDR had a significantly higher frequency of IL-6 -174 GC (OR 0.58; 95% CI 0.34-0.99; p = 0.011) and IL-6 -572 GG (OR 0.53; 95% CI 0.24-1.14; p = 0.016) than T2D controls. The mRNA expressions of the rs1800795 GC and rs1800796 GG genotype were significantly increased compared to other cases (Fsig = 0.002, p = 0.001, respectively), followed by a relative increase in IL-6 in protein. Conclusions: IL-6 genotypes of rs1800795 GC and rs1800796 GG might point to a relatively high risk for T2D patients suffering from PDR in a Chinese population and they were associated with elevation of IL-6 expression in both mRNA and protein.