Single Nucleotide Polymorphisms of Toll Like Receptors and Chronic Periodontitis

Objectives: Variations in clinical severity of periodontitis among individuals can be partly explained by genetics. Toll-like receptors (TLRs) play an essential role in modulating immune responses through recognition of pathogen-associated molecular patterns (PAMPs) expressed by microorganisms. Hence, functional polymorphisms of genes involved in regulation of PAMP-mediated inflammatory processes represent possible candidates for the elucidation of genetic background of periodontal disease. The aim of this study is to determine the frequency of single nucleotide polymorphisms (SNPs) in TLR-2, -4, and -9 genes in chronic periodontitis patients and periodontally healthy Caucasian subjects.

Methods: 120 chronic periodontitis subjects and 52 periodontally-healthy controls were enrolled with the study. Genotyping was performed in TLR2 (SNPID rs5743708), TLR4 (SNPID rs4984790), and TLR9 (SNPIDs rs187084 and rs5743836) genes by TaqManŽ allelic discrimination using Assay-by-DesignSM SNP Genotyping Assays (Applied Biosystems). Accuracy of genotyping was confirmed by known DNA samples of each genotype and by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analyses on selected samples. Chi-square analyses were performed to compare genotype and allele frequencies. Within diseased group, we investigated whether SNPs were related to disease severity by step-wise regression adjusted for age, gender, and smoking status.

Results: There was no statistically significant difference in the distribution of genotypes in diseased- and reference group for each polymorphism. We also could not demonstrate any genotype effect on the severity of periodontal disease as measured by mean pocket depth. Consistent with the previous reports, presence of polymorphic alleles for certain genes was low in the study population.

Conclusion: Based on findings of this study, polymorphisms of TLR-2, -4 and -9 genes are not related to chronic periodontitis in Caucasians. However, low copy number of certain alleles may warrant further investigations with increased sample size to explore the role of SNPs in TLRs in periodontal disease.

Supported by DEO7926 and P60MD002256-01