Abstract
Helicobacter pylori persistently colonizes the human gastrointestinal tract and is associated with chronic gastritis and, in some cases, peptic ulcer disease or gastric neoplasms. One factor in the persistence of this organism may be its inability to elicit a strong inflammatory response. Lipopolysaccharide (LPS) is a proinflammatory substance found in the cell walls of all gram-negative bacteria. H. pylori LPS has been found by several different measures to be less active than LPS from Enterobacteriaceae. This study addresses the role of CD14 and LPS-binding protein in the cellular response to H. pylori LPS. We report that H. pylori LPS activates mammalian cells expressing CD14 at much lower LPS concentrations than those for control cells not expressing CD14. The maximal activation of CD14-70Z/3 cells by H. pylori LPS also requires LPS-binding protein. H. pylori LPS at concentrations as high as 30 microg/ml does not elicit an interleukin-8 (IL-8) response from the epithelial cell line SW620 in the presence of CD14; 10 ng of Escherichia coli LPS per ml elicits a maximal IL-8 response. Furthermore, in contrast to some other types of LPS with little activity, H. pylori LPS does not inhibit the CD14-70Z/3 cell response to E. coli LPS. From these studies, we conclude that H. pylori LPS, though much less active than E. coli LPS, stimulates cells via CD14.