Takami Mimi, Terry Valeri, Petruzzelli Lilli
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical Center and Department of Veterans Affairs Medical Center, Ann Arbor, MI 48109, USA.
J Immunol. 2002 May 1;168(9):4559-66. doi: 10.4049/jimmunol.168.9.4559.
In human neutrophils, IL-8 induces chemotaxis, the respiratory burst, and granule release, and enhances cellular adhesion, a beta(2) integrin-dependent event. IL-8 stimulates neutrophil adhesion to purified fibrinogen in a Mac-1-dependent manner. Mitogen-activated protein kinase (MAPK) activation was detected in human neutrophil lysates after treatment with IL-8 and PMA, but not the activating mAb CBR LFA 1/2. IL-8-stimulated neutrophil adhesion to fibrinogen was blocked 50% by the MAPK/extracellular signal-related kinase-activating enzyme inhibitor PD098059. Adhesion was blocked approximately 75% by inhibition of the phosphatidylinositol-3 kinase (PI3K) pathway with LY294002, supporting that activation of both MAPK and PI3K may play a role in IL-8-dependent inside-out signals that activate Mac-1. Activation of MAPK was inhibited in IL-8-stimulated cells in the presence of PI3K inhibitors LY294002 or wortmannin, supporting a model in which PI3K is upstream of MAPK. IL-8-stimulated neutrophil adhesion was inhibited 50% by bisindolylmaleimide-I, implicating protein kinase C (PKC) in the intracellular signaling from the IL-8R to Mac-1. A 74-kDa molecular mass species was detected by an activation-specific Ab to PKC when cells were stimulated with PMA or IL-8, but not a beta(2)-activating Ab. Inhibition of either MAPK or PKC resulted in partial inhibition of IL-8-stimulated polymorphonuclear neutrophil adhesion, and treatment with both inhibitors simultaneously completely abolished IL-8-stimulated adhesion to ligand. Inhibition of PI3K blocked MAPK activation, but not PKC activation, suggesting a branch point that precedes PI3K activation. These data suggest that both MAPK and PKC are activated in response to IL-8 stimulation, and that these may represent independent pathways for beta(2) integrin activation in neutrophils.
在人类中性粒细胞中，白细胞介素-8（IL-8）可诱导趋化作用、呼吸爆发和颗粒释放，并增强细胞黏附，这是一种β2整合素依赖性事件。IL-8以Mac-1依赖性方式刺激中性粒细胞与纯化的纤维蛋白原黏附。在用IL-8和佛波酯（PMA）处理后的人类中性粒细胞裂解物中检测到丝裂原活化蛋白激酶（MAPK）激活，但激活单克隆抗体CBR LFA 1/2处理后未检测到。MAPK/细胞外信号调节激酶激活酶抑制剂PD098059可使IL-8刺激的中性粒细胞与纤维蛋白原的黏附被阻断50%。用LY294002抑制磷脂酰肌醇-3激酶（PI3K）途径可使黏附被阻断约75%，这支持MAPK和PI3K的激活可能在激活Mac-1的IL-8依赖性外向内信号中发挥作用。在存在PI3K抑制剂LY294002或渥曼青霉素的情况下，IL-8刺激细胞中MAPK的激活受到抑制，这支持了PI3K在MAPK上游的模型。双吲哚马来酰亚胺-I可使IL-8刺激的中性粒细胞黏附被抑制50%，这表明蛋白激酶C（PKC）参与了从IL-8受体到Mac-1的细胞内信号传导。当细胞用PMA或IL-8刺激时，用激活特异性抗体检测到一种74 kDa的PKC分子质量物种，但用β2激活抗体检测未发现。抑制MAPK或PKC会导致IL-8刺激的多形核中性粒细胞黏附部分受到抑制，同时用两种抑制剂处理可完全消除IL-8刺激的与配体的黏附。抑制PI3K可阻断MAPK激活，但不阻断PKC激活，这表明在PI3K激活之前存在一个分支点。这些数据表明，MAPK和PKC在对IL-8刺激的反应中均被激活，并且这些可能代表中性粒细胞中β2整合素激活的独立途径。
