Interactions between LPS moieties and macrophage pattern recognition receptors

Mammalian host organisms live their life constantly interacting with pathogenic and non-pathogenic Gram-negative bacteria. Commensal/symbiont strains are tolerated in the gut, while pathogens are kept at bay by the immune system. In contrast both commensals and pathogenic bacteria are targets of the immune system outside of the digestive system. Immune cells are activated upon contact with different constituents of bacterial cells like peptidoglycan, outer membrane proteins, fimbriae, bacterial DNA, etc. One of the dominant molecular targets affecting the immune cells is the lipopolysaccharide (LPS), an essential molecule of the cell wall of Gram-negative bacteria. In this review we discuss interactions of macrophages with the main LPS moieties lipid A, core and O-antigen regions.