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.