1. Oxidative stress-induced changes in pyridine nucleotides and chemoattractant 5-lipoxygenase products in aging neutrophils.
- Author
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Graham FD, Erlemann KR, Gravel S, Rokach J, and Powell WS
- Subjects
- Alcohol Oxidoreductases metabolism, Antioxidants pharmacology, Apoptosis drug effects, Arachidonate 5-Lipoxygenase immunology, Arachidonate 5-Lipoxygenase metabolism, Arachidonic Acids chemistry, Arachidonic Acids immunology, Biomimetics, Cells, Cultured, Cellular Senescence physiology, Chemotactic Factors chemistry, Chemotactic Factors immunology, Colforsin pharmacology, Cytochrome P-450 Enzyme System immunology, Cytochrome P-450 Enzyme System metabolism, Cytochrome P450 Family 4, Humans, Hydroxyeicosatetraenoic Acids chemistry, Leukotriene B4 chemistry, Leukotriene B4 immunology, Leukotriene B4 metabolism, NADP metabolism, Neutrophils drug effects, Neutrophils pathology, Oxidation-Reduction drug effects, Oxidative Stress, Pyridines chemistry, Pyridines immunology, Superoxide Dismutase chemistry, Arachidonic Acids metabolism, Chemotactic Factors metabolism, Hydroxyeicosatetraenoic Acids metabolism, Neutrophils physiology, Pyridines metabolism
- Abstract
Neutrophils spontaneously undergo apoptosis, which is associated with increased oxidative stress. We found that there is a dramatic shift in the formation of 5-lipoxygenase products during this process. Freshly isolated neutrophils rapidly convert leukotriene B(4) (LTB(4)) and 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) to their biologically inactive omega-oxidation products. However, omega-oxidation is impaired in neutrophils cultured for 24 h, when only 25% of the cells are nonapoptotic, resulting in the persistence of LTB(4) and a dramatic shift in 5-HETE metabolism to the potent granulocyte chemoattractant 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE). The reduced omega-oxidation activity seems to be due to a reduction in LTB(4) 20-hydroxylase activity, whereas the increased 5-oxo-ETE formation is caused by a dramatic increase in the 5-hydroxyeicosanoid dehydrogenase cofactor NADP(+). NAD(+), but not NADPH, also increased, as did the GSSG/GSH ratio, indicative of oxidative stress. The changes in 5-HETE metabolism and pyridine nucleotides were inhibited by antiapoptotic agents (GM-CSF, forskolin) and antioxidants (diphenylene iodonium, catalase, deferoxamine), suggesting the involvement of H(2)O(2) and possibly other reactive oxygen species. These results suggest that in severe inflammation, aging neutrophils that have evaded rapid uptake by macrophages may produce increased amounts of the chemoattractants 5-oxo-ETE and LTB(4), resulting in delayed resolution or exacerbation of the inflammatory process.
- Published
- 2009
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