Lipopolysaccharides (LPS)

Lipopolysaccharide (LPS), also known as endotoxin, is a major glycolipid constituent of the outer cell wall of gram-negative bacteria. LPS molecules typically consist of a strain-specific distal polysaccharide side chain known as the O-antigen, a hydrophilic core oligosaccharide, and a hydrophobic domain referred to as lipid A. Lipid A is covalently bound to the outer bacterial membrane and is responsible for the toxicity of LPS (1-3). LPS is a potent activator of the proinflammatory response in many mammalian cell types, including macrophages, monocytes, and endothelial cells. Investigators have demonstrated that LPS binds to the CD14/TLR4/MD2 receptor complex, which in turn induces inflammatory cytokines including TNF-α, Interleukin-1, and IFN-α, as well as numerous inflammatory proteins such as iNOS, NF-κB, RIG-1, and IRF-3 (4-6). 1.Raetz, C.R. and Whitfield, C. (2002) Annu Rev Biochem 71, 635-700. 2.Rietschel, E.T. et al. (1994) FASEB J 8, 217-25. 3.Maeshima, N. and Fernandez, R.C. (2013) Front Cell Infect Microbiol 3, 3. 4.Pålsson-McDermott, E.M. and O'Neill, L.A. (2004) Immunology 113, 153-62. 5.Wang, J. et al. (2008) J Immunol 180, 8011-9. 6.Zhang, F.X. et al. (1999) J Biol Chem 274, 7611-4.