RAGE-mediated neutrophil dysfunction is evoked by advanced glycation end products (AGEs)

Abstract

The accumulation of advanced glycation end products (AGEs) in the tissue and serum of subjects with diabetes has been linked to the pathogenesis of vascular complications. Because diabetes may be also complicated by increased susceptibility to recurrent infection, we investigated the effects of AGEs on human neutrophils, because their burst of activity immediately upon engagement of pathogens or other inflammatory triggers is critical to host response. We demonstrate the presence of receptor for advanced glycation end products (RAGE) at the message and protein levels. We also demonstrate that AGE albumin (but not control albumin) binds with high affinity to human neutrophils (Kd of 3.7±0.4 nM). The binding was blocked almost completely by excess soluble RAGE, anti-RAGE antibodies, or antibodies to CML-modified albumin. AGE albumin induced a dose-dependent increase in intracellular-free calcium as well as actin polymerization. Further, AGE albumin inhibited transendothelial migration and Staphylococcus aureus-induced but not fMLP-induced production of reactive oxygen metabolite. Moreover, although AGE albumin enhanced neutrophil phagocytosis of S. aureus, it inhibited bacterial killing. We conclude that functional RAGE is present on the plasma membrane of human neutrophils and is linked to Ca2+ and actin polymerization, and engagement of RAGE impairs neutrophil functions.