Protective effects of a novel RIPK3 antagonist against neutrophil necroptosis and formation of neutrophil extracellular traps

Functionally competent, highly purified neutrophils were isolated from healthy human donors. Neutrophil necroptosis and neutrophil extracellular trap (NET) formation were induced using TNF- in combination with the pan-caspase inhibitor zVAD-FMK and the IAP antagonist BV6. NETs were visualized, quantified, and morphologically characterized by fluorescence microscopy following staining with Hoechst 33342 and Sytox Green. Levels of extracellular, cell-free neutrophil elastase (NE), myeloperoxidase (MPO), and DNA were also measured as indicators of NET release. The ability of TACT507, a proprietary RIPK3 antagonist, to efficiently block NETs formation and NET related necroptosis was evaluated. TACT507 demonstrated concentration dependent, significant inhibition of neutrophil necroptosis and NETs formation. Summary SentenceIsolated human neutrophils treated ex vivo by TNF- in combination with apoptosis inhibitors, underwent necroptosis causing formation of neutrophil extracellular traps. This process was inhibited by the proprietary antagonist of RIPK3.