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

Abstract Neutrophils 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 lipid N -chloramines in vivo , their biological activity and neutralization. Using a chemical probe for N -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 in Escherichia coli and an important component of eukaryotic membranes, exhibited oxidative activity towards the redox-sensitive protein roGFP2, suggesting a role for lipid N -chloramines in protein oxidation. Conversely, the cellular antioxidant glutathione neutralized lipid N -chloramines by removing the chlorine moiety. We propose that lipid N -chloramines, like protein N -chloramines, are involved in inflammation and accelerate the host immune response.