title: Induction of human neutrophil apoptosis by nitric oxide donors: evidence for a caspase-dependent, cyclic-GMP-independent, mechanism.
abstract: This study investigated the regulatory effects of the major inflammatory mediator, nitric oxide (NO), on human neutrophil apoptosis in vitro. Co-culture of human neutrophils with the NO donors GEA 3162 (1,2,3,4-oxatriazolium,5-amino-3-(3,4-dichlorophenyl)-chloride) (10-100 microM) and 3-morpholino-sydnonimine (SIN-1) (0.3-3 mM) caused a dramatic and concentration-dependent induction of apoptosis. However, N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced neutrophil activation (actin reorganization and chemotaxis) was inhibited by GEA 3162 treatment. The pro-apoptotic effects of the NO donors were (i) unaffected by the soluble guanylate cyclase inhibitor LY-83583 (6-anilino-5,8-quinolinedione; 100 microM), (ii) antagonized by superoxide dismutase (6 microg/mL), (iii) mimicked by exogenous peroxynitrite (at concentrations >100 microM), and (iv) inhibited by the caspase inhibitor Z-Val-Ala-DL-Asp-fluoromethylketone (100 microM). The pro-apoptotic effect of the NO donors was not mimicked by the cell-permeable cyclic nucleotide analogue, N6,2-O-dibutyrylguanosine-3',5'-cyclic monophosphate (dibutyryl-cGMP) at concentrations < or =0.2 mM. Indeed, at high concentrations (> or =2 mM), dibutyryl-cGMP caused an inhibition of apoptosis. These results suggest that NO-mediated apoptosis, although caspase-dependent, is mediated by a cGMP-independent mechanism and involves the concurrent generation of oxygen free radicals and, potentially, peroxynitrite. Our data reveal a unique role for NO in inflammatory responses with differential effects upon neutrophil activation and survival, with important implications for the successful resolution of inflammation.
authors.affiliation: Department of Medicine (RIE), University of Edinburgh Medical School, UK.
authors.forename: C
authors.initials: C
authors.lastname: Ward
authors.forename: T H
authors.initials: TH
authors.lastname: Wong
authors.forename: J
authors.initials: J
authors.lastname: Murray
authors.forename: I
authors.initials: I
authors.lastname: Rahman
authors.forename: C
authors.initials: C
authors.lastname: Haslett
authors.forename: E R
authors.initials: ER
authors.lastname: Chilvers
authors.forename: A G
authors.initials: AG
authors.lastname: Rossi
mesh_terms: D000328:Adult; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D005609:Free Radicals / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007249:Inflammation / Q000473:pathology; D018375:Neutrophil Activation / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects* / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology
chemical_list: D005609:Free Radicals; D020030:Nitric Oxide Donors; D017382:Reactive Oxygen Species; D014230:Triazoles; D009569:Nitric Oxide; C082874:GEA 3162; D020169:Caspases; D006162:Guanylate Cyclase; D006152:Cyclic GMP