Association Of Polymorphisms Of Interleukin-6 And Its Receptor Genes With Chronic Periodontitis In Chinese People From Northwestern China

Aim:The aim of our investigation is to evaluate the association of interleukin-6 and interleukin-6 receptor gene polymorphisms with chronic Periodontitis (CP) in northwest Chinese Population, to provide evidence for the early diagnosis, therapy and prevention of CP.Material and Methods:A case-control study of 199 cases of chronic periodontitis patients and 216 healthy controls was performed. Genomic DNA was isolated from whole venous blood using phenol-chloroform extraction by the standard method. Single nucleotide polymorphisms (SNPs) in the interleukin-6 (IL-6) (-572 G/C,-1363 G/T) andIL-6R(-183 G/A,+48892 A/C)gene were analyzed using polymerase chain reaction (PCR), followed by restriction fragment length polymorphism(RFLP) analysis and agarose gel electrophoresis. The differences between the case groups and healthy groups were analysed by chi square test.Results:We found that the frequency of the IL-6-1363 GG genotype and G allele was significantly increased in the patients with chronic periodontitis compared with healthy controls (p=0.034,p=0.037, respectively), and GG genotype and G allele increased the risk of chronic periodontitis (respectively, odds ratio (OR)= 2.436,95% confidence interval (95% CI)=[1.048-5.665];OR=2.367,95% CI= [1.030-5.435]). Haplotype analysis of IL-6-1363 G/T and-572 G/C showed C/T had significant association with CP risk (p=0.024). The IL-6R+48892 A/C CC genotype and C allele were found to be protective against chronic periodontitis (OR =0.493,95% CI=[0.275-0.885];OR=0.725,95% CI=[0.549-0.958]). Haplotype analysis of IL-6R-183 G/A and+48892 A/C showed A/A and C/A had significant association with CP risk (p=0.0235, p=0.0002). In addition, IL-6R+48892 A/C polymorphisms were also associated with chronic periodontitis in woman subgroup (p=0.020, p=0.043, respectively), and there were no statistically significant differences between the frequencies of IL-6-572 G/C and IL-6R-183 G/A polymorphisms and chronic periodontitis.Conclusion:Our results suggest that the IL-6-1363 G/T and IL-6R+48892 A/C polymorphisms could affect the susceptibility for chronic periodontitis in northwest Chinese population. In addition, the polymorphisms of IL-6-572 G/C was probably different in different population and regions.