Toll-like receptor 4 gene polymorphism is associated with chronic periodontitis

Toll-like receptors (TLRs) contribute to the immune response by recognizing patterns presented by bacteria and other pathogens. These receptors have been implicated in the inflammatory response that contributes to gingivitis and periodontitis. Conflicting reports have suggested that variations in the genes encoding TLRs, particularly TLR2 and TLR4, may influence susceptibility to periodontitis. In this study, the contribution of variations in the genes encoding TLR2 and TLR4 in the context of periodontitis was examined in 254 patients with moderate periodontitis, 418 patients with severe periodontitis, and 260 healthy controls free of gum disease. Genomic DNA was extracted from participants' whole blood, and genotyping of TLR2/TLR4 as performed using real-time polymerase chain reaction with TaqMan MGB primer. The genotype, allele, and haplotype frequencies were compared among control, moderate periodontitis, and severe periodontitis groups. Statistical analysis was performed using chi-square and logistic regression analyses. Of the 9 polymorphic loci detected in the two genes, one, rs11536889 (G>C) in TLR4, displayed a statistically significant difference in distribution between individuals with moderate periodontitis and severe periodontitis (P<0.05). The distribution of the GG genotype in moderate periodontitis was higher than in the severe periodontitis group (P<0.05). Further, for the haplotype rs7873784, rs1927907, and rs1153688 of TLR4, the distribution of haplotype GCG was statistically different between moderate periodontitis and severe periodontitis (P<0.05, OR=1.501). These findings indicate that variation in TLR4 may affect chronic periodontitis susceptibility in a Han Chinese population.