Inhibition of tumor necrosis factor-alpha induced neutrophil apoptosis by cyclic AMP: involvement of caspase cascade.
Treatment of neutrophils with tumor necrosis factor-alpha (TNF-alpha) in the presence of cycloheximide induced apoptosis within 3 h, as evaluated by the occurrence of morphological nuclear changes characteristic of apoptosis. Pretreatment of neutrophils with dibutyryl cyclic AMP (dbcAMP) suppressed the TNF-alpha/cycloheximide-induced apoptosis in neutrophils in a concentration-dependent manner, while dbcAMP by itself did not induce any morphological changes. Forskolin, or a phosphodiesterase inhibitor, also produced a concentration-dependent inhibition on apoptosis. This inhibition by dbcAMP was completely reversed by pretreatment with the protein kinase A inhibitor, N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline sulphonamide (H-89). DbcAMP also inhibited the TNF-alpha/cycloheximide-induced activation of caspase-3, but it had no effect on the activation of caspase-8 in human neutrophils. Furthermore, dbcAMP did not directly inhibit activated caspase-3 activity. Inhibitor of protein kinase C, phosphatidylcholine-specific phospholipase C, tyrosine kinase, nitric oxide synthase, or granulocyte colony-stimulating factor or granulocyte monocyte colony-stimulating factor did not affect apoptosis. These results indicate that the elevation of levels of endogenous intracellular cyclic AMP and subsequent activation of protein kinase A play a crucial role in the prevention of apoptosis triggered by TNF-alpha/cycloheximide in human neutrophils, and that the possible target of cyclic AMP is a product in the metabolic pathway between caspase-8 and caspase-3.
Niwa
M
M
Department of Pharmacology, Gifu University School of Medicine, Japan. mniwa@cc.gifu-u.ac.jp
Hara
A
A
Kanamori
Y
Y
Matsuno
H
H
Kozawa
O
O
Yoshimi
N
N
Mori
H
H
Uematsu
T
T
D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D003994:Bucladesine / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006801:Humans; D066298:In Vitro Techniques; D009504:Neutrophils / Q000187:drug effects* / Q000473:pathology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D005576:Colforsin; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D003994:Bucladesine; D003513:Cycloheximide; D000242:Cyclic AMP; D011493:Protein Kinase C; D020169:Caspases