IFN? sensitizes macrophages to pathogen ligand killing via a unique caspase-8 and mitochondrial cell death pathway licensed by nitric oxide

Caspase-8 modulates TLR-induced gene transcription, which is only partially dependent on caspase-8 catalytic activity. Moreover, The slow kinetics of IFN? and LPS-induced BMDM killing offers the possibility that transcriptional responses may contribute to cell death activation. We performed 3' mRNA-sequencing to examine whether caspase-8 might contribute, at least in part, to IFN? and LPS-triggered macrophage death via its transcriptional role. We found that caspase-8-mediated transcriptional re-programming of BMDMs. Importantly, caspase-8 modulates expression of Bcl-2 family members and inducible nitric oxide synthase (iNOS) to promote activation of the mitochondrial apoptotic effectors, BAX and BAK. Overall design: BMDMs derived from Mlkl-/- and Mlkl-/-Caspase-8-/- mice (n =3 mice of each genotype) were primed with IFN? (50 ng/ml) overnight then stimulated with LPS (50 ng/ml) for 7 hours. 3' mRNA sequencing was performed on the samples.