Alveolar bone loss in relation to toll-like receptor 4 and 9 genotypes and Porphyromonas gingivalis carriage

Toll-like receptors (TLRs) are highly developed sensors to detect microbe-associated molecular patterns. Functional polymorphisms of the genes TLR4 and TLR9 were found to be associated with alveolar bone loss in a Porphyromonas gingivalis -induced periodontitis model in mice. Our aim was to examine whether such an association can be detected in a group of Finnish adults. Polymorphisms of TLR4 Asp299Gly (rs4986790) and TLR9 rs187084 (1486 T/C) were genotyped by pyrosequencing and PCR from the saliva samples of 223 adults (age range 40–60 years). Alveolar bone loss, measured from panoramic radiographs, were compared between TLR genotype groups according to subjects’ salivary carriage of P. gingivalis , measured using a single copy gene–based real-time PCR. The frequencies of TLR4 wild type and heterozygote variants were 87.4 % and 12.6 %, respectively, while those of TLR9 wild type, heterozygote, and homozygote variants were 25.6 %, 39.1 %, and 35.3 %, respectively. In the TLR4 heterozygote group, P. gingivalis -positive subjects had more alveolar bone loss than P. gingivalis -negative subjects ( p = 0.027), while no difference was observed in the wild type group. P. gingivalis -negative individuals with TLR9 heterozygotes exhibited significantly less alveolar bone loss compared to those with TLR9 wild type ( p = 0.007). Polymorphisms of TLR4 in P. gingivalis carriers seem to expose to alveolar bone loss. Polymorphisms of TLR9 can be protective against alveolar bone loss in the absence of P. gingivalis .