Mitochondrial Impairment Mediates Cytolysis in Anthrax Lethal Toxin-Treated Murine Macrophages

Anthrax Lethal Toxin Kills Macrophages in a Strain-Specific Manner by Apoptosis or Caspase-1-Mediated Necrosis

“…32,36 While caspase-1 deficient macrophages show reduced sensitivity to LT-mediated necrosis, 32,35 several studies suggest that caspase activation, while associated with LT-induced necrosis, is not a required event in this process. 36,37,45 In this study, we were able to address this issue, and found that complete inhibition of caspase-1 was needed to block rapid LT-killing. We found that the caspase-1 inhibitor Boc-D-cmk blocked IL-18 processing, as well as subsequent necrosis, in LT-treated macrophages.…”

“…It is conceivable that interleukin processing is involved in cytopathic effects. However, efficient LT killing occurs in the presence of protein biosynthesis inhibitors, 45 and cytokines are released only after cytolysis. This is consistent with the high susceptibility of macrophages lacking IL-1b or IL-18 to caspase-1-mediated necrosis.…”

“…Cell viability was analyzed by MTT assay as described previously. 18,45 Cells were either untreated or exposed to LT (500 ng/ml PA + 250 ng/ml LF) for the lengths of time indicated. Following LT treatment, MTT solution (5 mg/ml MTT in PBS) was added directly to wells and incubated at 37˚C for 4 hours.…”

“…The BALB/c-derived macrophage cell line J774A.1 undergo, like their corresponding primary cells, necrosis in response to LT challenge. 36,45,46 The inhibitors tested included the broad caspase inhibitors zVAD-fmk and Boc-D-fmk, as well as the caspase-1 specific inhibitors Boc-D-cmk and Ac-YVAD-cmk. Intriguingly, of all caspase inhibitors tested, only Boc-D-cmk blocked LT-induced necrosis, while zVAD-fmk, Ac-YVAD-cmk, and Boc-D-fmk offered only intermediate, or no protection (Fig.…”

Nullomer derived anticancer peptides (NulloPs): Differential lethal effects on normal and cancer cells in vitro

“…Peptide 9S1R at 50 µM almost completely shuts down ATP production in both cell lines (LnCap and MDA-MB-231) by the 2h time point, an effect more drastic than the sodium azide control. This is a toxic effect similar to that of anthrax toxin in J774A.1 cells [3,4]. In addition, at 25 µM peptide 9S1R reduces the ATP level by 50% at the 2h and 24h time points, and by 85% at the 48h time point.…”