LIPID-A ASSOCIATED PROTEINS FROM PERIODONTOPATHOGENIC BACTERIA INDUCEINTERLEUKIN-6 PRODUCTION BY HUMAN GINGIVAL FIBROBLASTS AND MONOCYTES

The aim of this study was to determine whether lipid A-associated prot eins (LAP) from two periodontopathogenic species of bacteria were able to stimulate interleukin-6 (IL-6) release from human gingival fibrobl asts and myelomonocytic cells. LAP and lipopolysaccharide (LPS) were e xtracted from Porphyromonas gingivalis and Prevotella intermedia and a dded to cultures of human gingival fibroblasts and mono-mac-6 monocyti c cells. Release of IL-6 into the culture supernatants was determined by ELISA. LAP and LPS from For. gingivalis, but not from Prev. interme dia, stimulated IL-6 release from both cell types in a dose-dependent manner although LPS was less potent than LAP in inducing IL-6 release from the fibroblasts. IL-6 was detectable in cultures of both cell typ es following stimulation with LAP from For. gingivalis at a concentrat ion as low as 10 ng/ml. In response to LAP from Prev. intermedia, IL-6 was produced by mono-mac-6 cells but not by fibroblasts. Our results show that bacterial cell wall components other than LPS can induce IL- 6 release from cells of the periodontium in vitro. The production of s uch potent immunomodulatory agents in vivo may contribute to the conne ctive tissue breakdown characteristic of chronic periodontitis.