title: Critical role of mitochondria, but not caspases, during glucocorticosteroid-induced human eosinophil apoptosis.
abstract: Glucocorticosteroids are potent anti-inflammatory drugs used in the treatment of eosinophilic disorders. These molecules directly promote eosinophil apoptosis, yet the molecular mechanisms regulating this process remain ill-defined. We show here that stimulation of human peripheral blood eosinophils with dexamethasone induced DNA fragmentation, chromatin and cytoplasm condensation, and caspase-3 activation, as assessed by the proteolysis of its zymogen form and by the increase of caspase-3-like activity in eosinophil lysates. These phenomena were accompanied by a reduced uptake of the mitochondrial potential-sensitive marker DiOC(6)(3), suggestive of mitochondrial membrane permeabilization. Eosinophil incubation with the caspase-3 inhibitor, Z-Asp-Glu-Val-Asp-fluromethylketone, or with the broad spectrum caspase inhibitor, Z-Val-Ala-Asp-fluromethylketone, inhibited caspase-3-like activity generation but failed to modify dexamethasone-mediated loss in mitochondrial transmembrane potential and eosinophil apoptosis. In contrast, bongkrekic acid, a ligand of the mitochondrial permeability transition pore component, adenine nucleotide translocator, prevented both dexamethasone-induced mitochondrial disruption and apoptosis. We conclude that the mitochondrial permeability transition pore, rather than the caspase cascade, plays a critical role in the propagation of glucocorticosteroid-mediated apoptotic signals in human eosinophils.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U408, Faculté de Médecine Xavier Bichat, Paris, France.
authors.forename: Séverine
authors.initials: S
authors.lastname: Létuvé
authors.forename: Anne
authors.initials: A
authors.lastname: Druilhe
authors.forename: Martine
authors.initials: M
authors.lastname: Grandsaigne
authors.forename: Michel
authors.initials: M
authors.lastname: Aubier
authors.forename: Marina
authors.initials: M
authors.lastname: Pretolani
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D001865:Bongkrekic Acid / Q000494:pharmacology; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D053938:DNA Fragmentation / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology; D007473:Ion Channels / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D000226:Mitochondrial ADP, ATP Translocases / Q000037:antagonists & inhibitors; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D009842:Oligopeptides / Q000494:pharmacology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000900:Anti-Bacterial Agents; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D007473:Ion Channels; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D009842:Oligopeptides; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D001865:Bongkrekic Acid; D003907:Dexamethasone; D000226:Mitochondrial ADP, ATP Translocases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases