Highly Motile Neutrophil Cytoplast ameliorate Bacterial Pneumonia

Abstract

Abstract Polymorphonuclear neutrophils (PMN) function as innate immune cell through rapid mobilization at site of infection and prompt phagocytosis and bactericidal activity. We addressed in vivo in mouse lungs the function of cytoplasts (PMNcyt), the PMN generated following release of extracellular traps (NETs). We found ~50% of PMN lost their nucleus post-NETosis following pneumonia induced by Pseudomonas aeruginosa (PA), and become PMNcyt. Interestingly, , PMNcyt in lung microvessels showed >2 greater velocity and > 3 greater deformability as compared to PMN. PMNcyt were also 9x more efficient in killing airway PA as compared to PMN. Using the protein arginine deiminase 4 (PAD4) inhibitor (Cl-amidine) to prevent NET formation in mice, we prevented the generation of PMNcyt demonstrating that PMNcyt were derived post-vital NETosis. We also showed PMNcyt retained the ability to phagocytose PA. Moreover, the inhibition of PMNcyt generation by PAD4 blocker induced severe lung injury in the pneumonia model, indicating an important anti-bacterial protective role of PMNcyt. Adoptive transfer of PMNcyt in PA infected mice also significantly reduced bacterial load and prevented lung tissue injury in mice. The results suggest a crucial host-defense function of PMNcyt generated post vital NETosis and their usefulness as cell-based therapy in inflammatory diseases such as pneumonia.