Expression of Toll-like Receptors in Diseased and Healthy Human Gingiva

Method: Human gingival biopsies were harvested from healthy individuals. In vivo TLRs gingival expression was studied by immunohistochemistry. Primary human gingival keratinocytes (HGK) and fibroblasts (HGF) were cultured and maintained till passage 3-4. Both cells were incubated in 18% and 1% O2 24 and 48 hours for TLR expressions by realtime-polymerase chain reaction and western blot.

Results: Peptides of TLR1, 2, 4, 5 and 6 were detectable in healthy and periodontitis gingival biopsies. TLR2 staining appeared enhanced in junctional compared to pocket epithelium, while TLR1, 4 and 5 were stained with higher intensity in periodontitis compared to healthy oral epithelium. Expressional location of TLR5 appeared to congregate much more at healthy basal epithelial layers compared to the diseased ones. All TLRs of interest were detected with enhanced staining densities in periodontitis connective tissue. The transcripts expression of TLR1, 3 and 6 were down-regulated compared to the up-regulation of TLR2 in 1% O2 HGK, while TLR3 and 5 were down-regulated, and TLR1 and 4 up-regulated in 1% O2 HGF. The accordingly peptides expressions showed both up-regulation of TLR6 in 1% O2 in HGK and HGF.

Conclusion: TLRs cooperate in the periodontitis guardianship by playing specialized immune defense role at epithelial layers and connective tissue separately. TLR2-6 heterodimer may play an important work not only in periodontopathogen defense, but also hypoxic resistance.