Experimental Study On Pathogenetic Mechanism Of Lipopolysaccharide(LPS) On Pulpitis

In order to investigate the effective methods of prevention and treatment of pulpal and periapical pathosis during the infection of Gram—negative anaerobic bacteria, this study was undertaken to elucidate the pathogeny of endotoxin LPS of anaerobic bacteria on pulpitis with the techniques of cell culture and animal experiment as follows:1. CD14 regulation in the induction of anaerobic bacteria's LPS on expression of cytokincs in monocytcsLPSs of root canal infectious prone bacteria Fusobacterum necleatum (Fn) and Bacteroides melaninogenicus (Bm) were used to stimulate human monocytes from peripheral blood in vitro. Then TNFα, IL—6 and IL— 8 wereexamined in the cultural supernatant with the method of ELISA. Results showed: If 5% of human serum was added into the culture medium, all the LPSs including Fn, Bm and control Escherichia coli (Ec) could induce the expression of TNFa, IL? and IL-8 from monocytes; but when the concentration of LPS was less than 100 ng/ ml, the induction could be blocked by anti-CD 14 antibody. When the concentration of LPS was more than 100 ng/ml, it could induce the expression of cytokines in the medium without serum, although the amounts of cytokines were extensively reduced when compared with in the medium containing serum, and this effect was independent from anti-CD 14 antibody. The induction ability of three different LPSs was Fn>Ec>Bm sequentially, while the amount of cytokines produced was IL?8 > TNFa > IL?6. The results indicated that Fn and Bm share the same mechanism as Ec in the induction of cytokines, which depends on the surface receptor CD14 of monocytes.