Role of nuclear factor kappa-B in TNF-induced cytoprotection.

Ischaemic heart disease (IHD) is a leading cause of death worldwide. Understanding prosurvival signalling pathways that protect against ischaemia-reperfusion injury (IRI) may assist in the development of novel cardioprotective strategies against IHD. In this regard, the transcription factor, nuclear factor kappa-B (NFκB) is activated by tumour necrosis factor (TNF), but its role in TNF-induced cytoprotection is unknown. Therefore, to investigate the role of NFκB in TNF-induced cytoprotection, C2C12 cells were pretreated with TNF (0.5 ng/ml) in the presence and absence of an NFκB inhibitor, pyrrolidine derivative of dithiocarbamate (PDTC; 100 µM). Cells were subjected to simulated IRI and treated with PDTC, either during TNF exposure or at reperfusion. Phosphorylation of IkB was measured after the TNF stimulus. Cytoprotection by TNF in cells subjected to IRI (cell viability: 43.7 ± 8.1% in control vs 70.6 ± 6.1% with TNF, < 0.001) was abrogated by co-administration of PDTC (40.6 ± 1.9%, < 0.001 vs TNF) but not by exposure to PDTC at reperfusion (70.7 ± 1.7%). Cytosolic IkB phosphorylation [1.5 ± 0.2 arbitrary units (AU) for TNF vs 1.0 ± 0.0 for untreated, < 0.01]) was increased after TNF exposure and this increase was abolished by co-administration with PDTC (0.8 ± 0.3 AU, < 0 01 vs TNF). Our data suggest that NFκB acts as a key component in TNF-induced cytoprotection. These findings may pave the way for the development of novel therapeutic drugs that target TNF/NFκB signalling to protect against IHD.