Objectives: LPS-binding protein (LBP) plays an important role in interaction with LPS and CD14 to modulate cytokine production in innate host response. Our recent studies find that LBP is expressed in human gingiva, and that Porphyromonas gingivalis LPS with lipid A structure heterogeneity differentially modulates the expression of LBP. This study further investigated the effects of LBP and P. gingivalis LPS interactions on the cytokines expression in human oral keratinocytes (HOKs).
Methods: HOKs was pretreated with various concentrations of the recombinant human LBP (rhLBP) for 60 min prior to stimulation with P. gingivalis LPS1435/1449 and LPS1690 for 30 min to 24 h. The mRNA expression of IL-6 and IL-8 was detected by real-time PCR. The peptides of IL-6, IL-8, IL-1b, IL-1ra and IL-10 were analyzed by ELISA.
Results: IL-6 and IL-8 expression was up-regulated significantly upon stimulation with P. gingivalis LPS1690 (100ng/ml and 1µg/ml) and P. gingivalis LPS1435/1449 (10ng/ml) at different time points. 100ng/ml or 1µg/ml of rhLBP dramatically up-regulated the IL-6 and IL-8 expression even without the following stimulation of P. gingivalis LPS. However, the rhLBP induced IL-6 and IL-8 expression was down-regulated upon the addition of P. gingivalis LPS1435/1449 and P. gingivalis LPS1690.
Conclusion: This study suggests that LBP may up-regulate the expression of IL-6 and IL-8 in HOKs without the interaction with LPS. Further study is warranted to clarify the mechanisms involved in LBP modulation and regulation of cytokine expression in host cells. (Supported by Hong Kong RGC, No. HKU766909M)