Caspase-8 Activation Precedes Alterations of Mitochondrial Membrane Potential during Monocyte Apoptosis Induced by Phagocytosis and Killing of Staphylococcus aureus
| Autor: | Jarosław Baran, Kazimierz Weglarczyk, Juliusz Pryjma, Marek Zembala |
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| Rok vydání: | 2004 |
| Předmět: |
Staphylococcus aureus
Programmed cell death Phagocytosis Immunology Apoptosis Caspase 3 In Vitro Techniques Biology Caspase 8 Microbiology Monocytes Membrane Potentials medicine Humans chemistry.chemical_classification Host Response and Inflammation Reactive oxygen species Monocyte Cytochrome c Molecular biology Immunity Innate Mitochondria Enzyme Activation Infectious Diseases medicine.anatomical_structure chemistry Caspases biology.protein Parasitology Reactive Oxygen Species |
| Zdroj: | Infection and Immunity. 72:2590-2597 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.72.5.2590-2597.2004 |
| Popis: | Human peripheral blood monocytes become apoptotic following phagocytosis and killing of Staphylococcus aureus . Although this type of monocyte apoptosis is known to be initiated by Fas-Fas ligand (FasL) interactions, the downstream signaling pathway has not been determined. In this work the involvement of mitochondria and the kinetics of caspase-8 and caspase-3 activation after phagocytosis of S. aureus were studied. Caspase-8 activity was measured in cell lysates by using the fluorogenic substrate Ac-IETD-AFC. Active caspase-3 levels and mitochondrial membrane potential (Δψ m ) were measured in whole cells by flow cytometry using monoclonal antibodies reacting with activated caspase-3 and chloromethyl-X-rosamine, respectively. The results show that caspase-8 was activated shortly after phagocytosis of bacteria. Caspase-8 activation was followed by progressive disruption of Δψ m , which is associated with the production of reactive oxygen intermediates. The irreversible caspase-8 inhibitor zIETD-FMK prevented the disruption of Δψ m and the release of cytochrome c from S. aureus -exposed monocytes. Caspase-3 activation occurred following disruption of Δψ m . These results strongly suggest that apoptosis of monocytes that have phagocytosed and killed S. aureus is driven by the Fas-FasL-initiated pathway, which is typical for type II cells. |
| Databáze: | OpenAIRE |
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