Escherichia coli and Porphyromonas gingivalis lipopolysaccharide interactions with CD14: Implications for myeloid and nonmyeloid cell activation

Porphyromonas gingivalis, a gram-negative bacterium, is an etiologic agent for adult periodontitis. Lipopolysaccharide (LPS) released from this bacter ium can react with numerous host cell types. P. gingivalis LPS stimulates t umor necrosis factor cu and interleukin-lp secretion from monocytes (myeloi d) but does not elicit E-selectin expression from human endothelial cells ( nonmyeloid). In contrast, Escherichia coil LPS facilitates expression of th ese inflammatory mediators through CD14-dependent pathways on both myeloid and nonmyeloid cells. LPS binding studies have revealed that although P. gi ngivalis and E. coli LPSs bind to CD14 differently, this fact does not adeq uately explain the lack of endothelial cell activation by P. gingivalis LPS . Rather, LPS binding site and blocking monoclonal antibody epitope mapping studies have suggested that CD14 presents a charged surface that captures different microbial ligands by electrostatic interactions. We propose that human endothelial cells do not respond to P. gingivalis LPS because of thei r inability to "recognize" CD14-P. gingivalis LPS complexes.