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Broad-spectrum caspase inhibition paradoxically augments cell death in TNF-alpha -stimulated neutrophils.
Title | Broad-spectrum caspase inhibition paradoxically augments cell death in TNF-alpha -stimulated neutrophils. |
Publication Type | Journal Article |
Year of Publication | 2003 |
Authors | Liu, C-Y, Takemasa, A, W Liles, C, Goodman, RB, Jonas, M, Rosen, H, Chi, E, Winn, RK, Harlan, JM, Chuang, PI |
Journal | Blood |
Volume | 101 |
Issue | 1 |
Pagination | 295-304 |
Date Published | 2003 Jan 1 |
ISSN | 0006-4971 |
Keywords | Case-Control Studies, Caspase Inhibitors, Cell Death, Enzyme Inhibitors, Humans, Kinetics, NADPH Oxidase, Neutrophils, Oligopeptides, Reactive Oxygen Species, Tumor Necrosis Factor-alpha |
Abstract | It is increasingly clear that there are caspase-dependent and -independent mechanisms for the execution of cell death and that the utilization of these mechanisms is stimulus- and cell type-dependent. Intriguingly, broad-spectrum caspase inhibition enhances death receptor agonist-induced cell death in a few transformed cell lines. Endogenously produced oxidants are causally linked to necroticlike cell death in these instances. We report here that broad-spectrum caspase inhibitors effectively attenuated apoptosis induced in human neutrophils by incubation with agonistic anti-Fas antibody or by coincubation with tumor necrosis factor-alpha (TNF-alpha) and cycloheximide ex vivo. In contrast, the same caspase inhibitors could augment cell death upon stimulation by TNF-alpha alone during the 6-hour time course examined. Caspase inhibitor-sensitized, TNF-alpha-stimulated, dying neutrophils exhibit apoptoticlike and necroticlike features. This occurred without apparent alteration in nuclear factor-kappaB (NF-kappaB) activation. Nevertheless, intracellular oxidant production was enhanced and sustained in caspase inhibitor-sensitized, TNF-alpha-stimulated neutrophils obtained from healthy subjects. However, despite reduced or absent intracellular oxidant production following TNF-alpha stimulation, cell death was also augmented in neutrophils isolated from patients with chronic granulomatous disease incubated with a caspase inhibitor and TNF-alpha. These results demonstrate that, in human neutrophils, TNF-alpha induces a caspase-independent but protein synthesis-dependent cell death signal. Furthermore, they suggest that TNF-alpha activates a caspase-dependent pathway that negatively regulates reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. |
DOI | 10.1182/blood-2001-12-0266 |
Alternate Journal | Blood |
PubMed ID | 12393619 |