Combination of LPS and z-VAD-FMK mediates necroptosis in IFN-γ-pretreated macrophages

AIM:To explore the mechanism of necroptosis in M1 macrophages mediated by lipopolysaccharide (LPS) combined with z-VAD-FMK. METHODS:THP-1 cells were induced to differentiate into M0 and M1 macrophages with phorbol 12-myristate 13-acetate (PMA) and interferon-γ (IFN-γ). The release of lactate dehydrogenase (LDH) and TUNEL-positive cells at different time points after LPS (100 μg/L) treatment were detected, and the effects of different inhibitors were observed. The protein levels of receptor-interacting protein (RIP) 1, RIP3, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), P38 and NOD-like receptor protein 3 (NLRP3) were determined by Wes-tern blot. RESULTS:LPS mediated cell death, and its combination with z-VAD-FMK specifically mediated necroptosis in M1 macrophages rather than M0 ones. The expression of RIP3 and NLRP3 was upregulated by IFN-γ, and LPS-mediated phosphorylation of JNK was also enhanced by IFN-γ. The inhibitors against RIP3 and JNK partly blocked LDH release mediated by LPS combined with z-VAD-FMK. CONCLUSION:Combination of LPS and z-VAD-FMK mediates necroptosis in IFN-γ-pretreated macrophages possibly by upregulation of RIP3 and enhancement of LPS-mediated JNK phosphorylation.