Department of Anesthetics, Chang Gung Memorial Hospital, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
Free Radic Biol Med. 2010 Jan 15;48(2):240-54. doi: 10.1016/j.freeradbiomed.2009.10.047. Epub 2009 Nov 3.
Exposure to cigarette smoke extract (CSE) leads to airway and lung inflammation through an oxidant-antioxidant imbalance. Cyclooxygenase-2 (COX-2) and prostaglandin E(2) (PGE(2)) have been shown to play critical roles in respiratory inflammation. Here, we show that COX-2/PGE(2)/IL-6 induction is dependent on Toll-like receptor 4 (TLR4)/NADPH oxidase signaling in human tracheal smooth muscle cells (HTSMCs). CSE induced COX-2 expression in vitro in HTSMCs and in vivo in the airways of mice. CSE also directly caused an increase in TLR4. Moreover, CSE-regulated COX-2, PGE(2), and IL-6 generation was inhibited by pretreatment with TLR4 Ab; inhibitors of c-Src (PP1), NADPH oxidase (diphenylene iodonium chloride and apocynin), p38 MAPK (SB202190), MEK1/2 (U0126), JNK1/2 (SP600125), and NF-kappaB (helenalin); a ROS scavenger (N-acetyl-l-cysteine); and transfection with siRNA of TLR4, MyD88, TRAF6, Src, p47(phox), p38, p42, JNK2, or p65. CSE-induced leukocyte numbers in BAL fluid were also reduced by pretreatment with these inhibitors. Furthermore, CSE induced p47(phox) translocation and TLR4/MyD88/TRAF6 and c-Src/p47(phox) complex formation. We found that PGE(2) enhanced IL-6 production in HTSMCs and leukocyte count in BAL fluid. In addition, treatment with nicotine could induce COX-2, PGE(2), and IL-6 generation in in vivo and in vitro studies. These results demonstrate that CSE-induced ROS generation was mediated through the TLR4/MyD88/TRAF6/c-Src/NADPH oxidase pathway, in turn initiated the activation of MAPKs and NF-kappaB, and ultimately induced COX-2/PGE(2)/IL-6-dependent airway inflammation.
香烟烟雾提取物 (CSE) 通过氧化还原失衡导致气道和肺部炎症。已经表明环氧化酶-2 (COX-2) 和前列腺素 E(2) (PGE(2)) 在呼吸炎症中发挥关键作用。在这里，我们表明 COX-2/PGE(2)/IL-6 的诱导依赖于人类气管平滑肌细胞 (HTSMCs) 中的 Toll 样受体 4 (TLR4)/NADPH 氧化酶信号。CSE 在体外诱导 HTSMCs 中的 COX-2 表达和体内小鼠气道中的 COX-2 表达。CSE 还直接导致 TLR4 增加。此外，用 TLR4 Ab 预处理可抑制 CSE 调节的 COX-2、PGE(2)和 IL-6 的产生；c-Src (PP1)、NADPH 氧化酶 (二苯基碘氯和 apocynin)、p38 MAPK (SB202190)、MEK1/2 (U0126)、JNK1/2 (SP600125) 和 NF-kappaB (helenalin) 的抑制剂；ROS 清除剂 (N-乙酰-l-半胱氨酸)；以及 TLR4、MyD88、TRAF6、Src、p47(phox)、p38、p42、JNK2 或 p65 的 siRNA 转染。用这些抑制剂预处理也减少了 CSE 诱导的 BAL 液中白细胞数量。此外，CSE 诱导 p47(phox)易位和 TLR4/MyD88/TRAF6 和 c-Src/p47(phox) 复合物形成。我们发现 PGE(2)增强了 HTSMCs 中 IL-6 的产生和 BAL 液中白细胞的计数。此外，在体内和体外研究中，尼古丁处理可诱导 COX-2、PGE(2)和 IL-6 的产生。这些结果表明，CSE 诱导的 ROS 生成是通过 TLR4/MyD88/TRAF6/c-Src/NADPH 氧化酶途径介导的，进而启动 MAPK 和 NF-kappaB 的激活，最终诱导 COX-2/PGE(2)/IL-6 依赖性气道炎症。
