HOCl Forms LipidN-Chloramines in Cell Membranes of Bacteria and Immune Cells

Abstract

AbstractNeutrophils orchestrate a coordinated attack on bacteria, combining phagocytosis with a potent cocktail of oxidants, including the highly toxic hypochlorous acid (HOCl), renowned for its deleterious effects on proteins. Here, we examined the occurrence of lipidN-chloraminesin vivo, their biological activity and neutralization. Using a chemical probe forN-chloramines, we demonstrate their formation in the membranes of bacteria and monocytic cells exposed to physiologically relevant concentrations of HOCl.N-chlorinated model membranes composed of phosphatidylethanolamine, the major membrane lipid inEscherichia coliand an important component of eukaryotic membranes, exhibited oxidative activity towards the redox-sensitive protein roGFP2, suggesting a role for lipidN-chloramines in protein oxidation. Conversely, the cellular antioxidant glutathione neutralized lipidN-chloramines by removing the chlorine moiety. We propose that lipidN-chloramines, like proteinN-chloramines, are involved in inflammation and accelerate the host immune response.