The Core Lipopolysaccharide ofEscherichia coliIs a Ligand for the Dendritic-Cell-Specific Intercellular Adhesion Molecule Nonintegrin CD209 Receptor

Abstract

The dendritic-cell-specific intercellular adhesion molecule nonintegrin (DC-SIGN) CD209 is a receptor forEscherichia coliK-12 that promotes bacterial adherence and phagocytosis. However, the ligand ofE. colifor DC-SIGN has not yet been identified. In this study, we found that DC-SIGN did not mediate the phagocytosis of several pathogenic strains ofE. coli, including enteropathogenicE. coli, enterohemorrhagicE. coli, enterotoxigenicE. coli, and uropathogenicE. coli, in dendritic cells or HeLa cells expressing human DC-SIGN antigen. However, we showed that an outer core lipopolysaccharide (LPS) (rough) mutant, unlike an inner core LPS (deep rough) mutant or O-antigen-expressing recombinant ofE. coliK-12 was phagocytosed. These results demonstrate that the host cells expressing DC-SIGN can phagocytoseE. coliin part by interacting with the complete core region of the LPS molecule. These results provide a mechanism for how O antigen acts as an antiphagocytic factor.