The Association Of Genetic Susceptibility Between Toll-Like Receptor 4 Polymorphisms And Diabetic Retinopathy In Chinese Patients With Type 2 Diabetes

Purpose:Toll-like receptor 4 (TLR4)is a pattern recognition receptor, which is involved in identifying microbial composition of bateria and virus, etc, induces auto-immune response, recognizes invasive baceria and initiates inflammatory reaction, so it plays a critical role in inflammatory signal pathway. Many studies have shown that lesion of the blood-retinal barrier is central to the earlier development of diabetic retinopathy (DR), inflammatory reaction is important contributor to the development of DR and plays an important role.On the other hand, DR is thought to be a disease caused by many factors, the aetiology of DR continues to be largely unknown.The knowledge of the risk factors is important to the prevention of DR.Therefore we designed this study to determine whether TLR4 gene polymorphism are associated with DR in a Han Chinese population and which risk factors involved in the development of DR.Methods:A total of 236 patients with type 2 diabetes and 274 age-matched, sex-matched and ethnicity-matched healthy controls were recruited,venous blood samples were obtained from both of them.Genomic DNAs were extracted from peripheral venous blood,rs 10759931,rs 1927911 and rs1927914 from genomic DNA of both cases and controls were genotyped through the use of PCR restriction fragment length polymorphism (PCR-RFLP) assay.Difference in age between cases and controls was assessed by t-test;Significance of difference between cases and controls in the genotype distribution of rs 10759931,rs 1927911 and rs 1927914 were evaluated with the use of x2 analysis. Clinical data from patients, such as blood pressure, blood glucose level,blood lipid level and living environment,etc, were collected to further explore the risk factors leading to DR.Results:Three single-nucleotide polymorphisms (SNPs) (rs10759931,rs1927911 and rs1927914) in TLR4 gene were successfully genotyped, three analyzed polymorphisms in TLR4 gene were in Hardy-Weinberg equilibrium both in the patients and the controls. The frequency of the TT genotype of rs1927914 was significantly decreased in the patients with type 2 diabetes,which revealed significantly statistical difference after Bonferroni correction (p=0.02, OR=0.57,95% CI 0.37 to 0.83); A significantly higher frequency of the C allele of rs1927914 was observed in the patients with type 2 diabetes compared with the controls after Bonferroni correction (p=0.01, OR=1.46,95%CI 1.13 to 1.88). On the other hand, significantly increased frequency of the CC genotype of rs1927911 was observed in the patients with type 2 diabetes compared with the healthy controls after Bonferroni correction(p=0.03, OR=1.67,95%CI 1.17 to 2.39); The frequency of the C allele of rs1927911 was significantly increased in the patients with type 2 diabetes compared with the healthy controls(p=0.045, OR=1.38 95% CI 1.06 to 1.80). A comparison of the distributions of genotypes and alleles of rs10759931 revealed no statistically significant difference between the patients with DR and the controls (p>0.05).The frequency of C allele of the rs1927914 was significantly increased in the DR group compared with those of the control group after Bonferroni correction(p=0.006, OR 1.51,95% CI 1.13 to 2.03).No signicant differences were detected between patients and controls with regard to all haplotypes.Multiple risk factors contributed to the development of DR.This study showed long diabetes duration(LDD), high level of glycosylated hemoglobin(GH), high level of triglyceride(TG) and low density lipoprotein(LDL) were important contributors to the development of DR through stratified analysis. This study revealed LDD, high level of GH and LDL were risk factors leading to DR after Logistic regression analysis.Conclusions:This study suggested that the rs1927914 and rs1927911 were associated with the susceptibility to T2DM, and the rs1927914 was associated with the susceptibility to DR in a Han Chinese population.The other two tested SNPs were not found to be associated with DR. Long diabetes duration, high level of glycosylated hemoglobin and low density lipoprotein are risk factors in the pathogenesis of DR.