RAGE in Neutrophils: A Sensor for Pathogen-Associated Structures and Beyond

Background/Objectives: Neutrophils express the receptor for advanced glycation end products (RAGE), but its role in the responses of neutrophils to bacteria is not well understood. Methods: Human peripheral neutrophils were isolated from blood of healthy donors. Fluorescent-based techniques and spectroscopy were used to assess calcium flux, ROS/RNS formation and phagocytic activity. Cellular expression of the PAGE-antigen was studied using immunofluorescence microscopy and flow cytometry. ELISA was used to quantify sRAGE in the culture medium. Results: We studied human peripheral neutrophils interacting with gram-negative bacteria S. typhimurium and asked how RAGE controls the neutrophil cellular responses. Blocking RAGE with the specific inhibitor FPS-ZM1 reduced bacteria-induced calcium signals, reactive oxygen species, nitric oxide production, and phagocytosis. We also found that neutrophil adhesion and stimulation by bacteria, lipopolysaccharide, or fMLP caused rapid release of soluble RAGE (sRAGE) into the cell environment. Immunofluorescence and flow cytometry showed low RAGE at the plasma membrane but abundant intracellular RAGE, which decreased on activation. Conclusions: Our data support a dual role of RAGE in neutrophils as both a membrane sensor and a secreted regulator.