Truett A P, Verghese M W, Dillon S B, Snyderman R
Howard Hughes Medical Institute, Department of Medicine, Duke University Medical Center, Durham, NC 27710.
Proc Natl Acad Sci U S A. 1988 Mar;85(5):1549-53. doi: 10.1073/pnas.85.5.1549.
Metabolic pathways involved in the activation of polymorphonuclear leukocytes (PMNs) were characterized by using chemoattractants with equivalent chemotactic activity but widely disparate ability to stimulate superoxide production [N-formylmethionylleucylphenylalanine (fMet-Leu-Phe) much greater than leukotriene B4]. Leukotriene B4 stimulated a low level of superoxide production that plateaued at 60 sec, whereas with fMet-Leu-Phe the response continued to increase for 5 min. Both agents produced equivalent initial rises in diacylglycerol (acyl2Gro) (less than or equal to 30 sec); however, only fMet-Leu-Phe induced a second increase of acyl2Gro peaking at ca. 120 sec. Both chemoattractants also caused an equivalent initial (less than or equal to 10 sec) rise in intracellular calcium; however, the elevation induced by fMet-Leu-Phe was more sustained. We sought to determine the biochemical mechanisms underlying these discrepancies. Superoxide production and the second phase of acyl2Gro generation were both inhibited ca. 56% by depleting extracellular calcium or ca. 79% by buffering intracellular calcium. Cytochalasin B greatly enhanced the respiratory burst, acyl2Gro production, and calcium influx, but not inositolphospholipid turnover in PMNs stimulated with chemoattractants. These data indicate that sequential metabolic pathways activate the respiratory burst in PMNs stimulated by chemoattractants. The response is initiated by inositolpolyphospholipid hydrolysis, which results in rapid (less than or equal to 5 sec) calcium mobilization from intracellular stores and acyl2Gro release (peak at ca. 30 sec). To fully activate the respiratory burst, the chemoattractant must also trigger calcium influx, which leads to a sustained cytosolic calcium elevation. This supports a prolonged new phase of acyl2Gro production that is independent of inositolphospholipid hydrolysis and is correlated with superoxide production.
通过使用具有同等趋化活性但刺激超氧化物产生能力差异很大的趋化因子 [N-甲酰甲硫氨酰亮氨酰苯丙氨酸（fMet-Leu-Phe）远大于白三烯B4]，对参与多形核白细胞（PMN）激活的代谢途径进行了表征。白三烯B4刺激产生的超氧化物水平较低，在60秒时达到平稳状态，而用fMet-Leu-Phe刺激时，反应持续增加5分钟。两种因子均使二酰基甘油（acyl2Gro）产生同等程度的初始升高（小于或等于30秒）；然而，只有fMet-Leu-Phe诱导acyl2Gro第二次升高，在约120秒时达到峰值。两种趋化因子还引起细胞内钙同等程度的初始升高（小于或等于10秒）；然而，fMet-Leu-Phe诱导的升高更持久。我们试图确定这些差异背后的生化机制。通过耗尽细胞外钙，超氧化物产生和acyl2Gro生成的第二阶段均被抑制约56%，或通过缓冲细胞内钙被抑制约79%。细胞松弛素B极大地增强了趋化因子刺激的PMN中的呼吸爆发、acyl2Gro产生和钙内流，但不增强肌醇磷脂周转。这些数据表明，连续的代谢途径激活了趋化因子刺激的PMN中的呼吸爆发。反应由肌醇多磷脂水解引发，这导致细胞内储存的钙迅速（小于或等于5秒）动员和acyl2Gro释放（在约30秒时达到峰值）。为了完全激活呼吸爆发，趋化因子还必须触发钙内流，这导致细胞质钙持续升高。这支持了acyl2Gro产生的延长的新阶段，该阶段独立于肌醇磷脂水解并与超氧化物产生相关。
