OBJECTIVETo determine the effect of Porphyromonas gingivalis lipopolysaccharide (LPS) on induced secretion of inflammatory cytokines by different cell lines.

METHODSLPS of P. gingivalis strain ATCC33277 (Pg-LPS) was extracted with phenol-water method, and identified by Limulus test and infrared spectrum analysis. KB, HGF-1 and THP-1 cells were treated with Pg-LPS of different concentrations and time duration, a commercial LPS of E.coli strain O111:B4 (E-LPS) was used as the control. TNF-alpha, IL-1beta, IL-6 and IL-8 levels in culture supernatants were measured by quantitative ELISA.

RESULTThe minimal dosages of both Pg-LPS and E-LPS to solidify Limulus agents were 15 ng/ml and their infrared spectrums were similar. With the treatment of Pg-LPS or E-LPS, the TNF-alpha and IL-1beta levels secreted by HGF-1 cells were remarkably increased with a single perk (P<0.01) while a continuous enhancement of secretion by THP-1 cells was observed (P<0.01). Either Pg-LPS or E-LPS stimulated HGF-1 or THP-1 cells to continuously increase the secretion of IL-6 (P<0.01). Both Pg-LPS and E-LPS induced IL-8 secretion by THP-1 cells (P<0.01), but only Pg-LPS showed the similar effect on HGF-1 cells (P<0.01). Neither Pg-LPS nor E-LPS induced KB cells to secrete inflammatory cytokines.

CONCLUSIONPg-LPS can promote target cells to increase their secretion of inflammatory cytokines. KB cells can not be used as the target cell to determine inflammation-causing effect of LPS.