Rapid High-Throughput Method for Investigating Physiological Regulation of Neutrophil Extracellular Trap Formation

Background Neutrophils, the most abundant white blood cells in humans, play pivotal roles in innate immunity, rapidly migrating to sites of infection and inflammation to phagocytose, neutralize, and eliminate invading pathogens. Neutrophil Extracellular Trap (NET) formation is increasingly recognized as an essential rapid innate immune response, but when dysregulated contributes to pathogenesis of sepsis and immunothrombotic disease. Objectives Current NETosis models are limited, routinely employing non-physiological triggers that can bypass natural NET regulatory pathways. Models utilizing isolated neutrophils and immortalized cell lines, do not reflect the complex biology underlying neutrophil activation and NETosis, that occurs in whole-blood. To our knowledge, we report the first human ex-vivo model utilizing naturally occurring molecules to induce NETosis in whole blood. This approach could be used for drug screening and, importantly, inadvertent activators of NETosis. Methods Here we describe a novel, high-throughput ex-vivo whole blood induced NETosis model using combinatorial pooling of native NETosis inducing factors in a more biologically relevant Synthetic-Sepsis™ model. Results We found different combinations of factors evoked distinct neutrophil responses in the rate of NET generation and/or magnitude of NETosis. Despite inter-donor variability, similar sets of pro-inflammatory molecules induced consistent responses across donors. We found at least three biological triggers, were necessary to induce NETosis in our system including either TNF-α or LT-α. Conclusion These findings emphasize the importance of investigating neutrophil physiology in a biologically relevant context to enable a better understanding of disease pathology, risk factors, and therapeutic targets, potentially, providing novel strategies for disease intervention and treatment.