Background: This study aimed to investigate the interrelationship of in vivo expression of lipopolysaccharide-binding protein (LBP) and membrane-bound CD14 (mCD14) in human gingival tissues as well as the coexpression of Toll-like receptors (TLR) 2 and 4 in association with periodontal conditions.
Methods: Gingival biopsies were collected from 43 subjects with chronic periodontitis, including periodontal pocket tissues (PoTs) and clinically healthy gingival tissues (HT-Ps), and from 15 periodontally healthy subjects as controls (HT-Cs). The expression of LBP, CD14, TLR 2, and TLR 4 was detected by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR).
Results: LBP and mCD14 peptides were simultaneously detected in 91% of PoTs, 85% of HT-Ps, and 100% of HT-Cs. LBP and mCD14 mRNAs were simultaneously detected in 55% of PoTs, 55% of HT-Ps, and 75% of HT-Cs. The expression of LBP was confined to the gingival epithelium, whereas mCD14 was observed around the epithelium-connective tissue interface. A positive correlation existed between LBP and mCD14 peptides in both detection expression (r(s) = 0.608; P <0.001) and expression levels (r = 0.304; P <0.05) of these two molecules. In PoTs, TLR 2 was detected in both pocket epithelia and macrophage-like cells in connective tissues, whereas TLR 4 was predominantly detected in connective tissues. In HT-Ps and HT-Cs, a weak expression of TLR 2 was found in gingival epithelia, and no TLR 4 expression was detected. In PoTs, mCD14 was codetected on CD68-labeled macrophages in the underlying connective tissues of pocket epithelium as well as on CD1a-labeled dendritic cells in the pocket epithelium and connective tissues interface. No similar expression profile was detected in HT-Ps and HT-Cs.
Conclusions: This study suggests that the in vivo expression of LBP and mCD14 may be interrelated. Altered cellular expression profiles of mCD14 and TLR 2 and 4 in periodontal pocket tissues imply that these pattern recognition receptors may play a role in periodontal pathogenesis.