Ko Hsin-Kuo, Lee Hung-Fu, Lin An-Hsuan, Liu Meng-Han, Liu Ching-I, Lee Tzong-Shyuan, Kou Yu Ru
Department of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Respiratory Therapy, Taipei Veterans General Hospital, Taipei, Taiwan.
J Cell Physiol. 2015 Aug;230(8):1781-93. doi: 10.1002/jcp.24881.
Inhaled cigarette smoke (CS) causes persistent lung inflammation in smokers. Interleukin 8 (IL-8) released from macrophages is a key chemokine during initiation and progression of CS-induced lung inflammation, yet its regulation is largely unknown. AMP-activated protein kinase (AMPK), a crucial energy homeostasis regulator, may modulate inflammation. Here we report that CS extract (CSE) increased the level of intracellular reactive oxygen species (ROS), activating AMPK, mitogen-activated protein kinases (MAPKs), and NF-κB, as well as inducing IL-8, in human macrophages. N-acetyl-cysteine (ROS scavenger) or hexamethonium [nicotinic acetylcholine receptor (nAChR) antagonist] attenuated the CSE-induced increase in intracellular ROS, activation of AMPK and NF-κB, as well as IL-8 induction, which suggests that nAChRs and ROS are important. Prevention of AMPK activation by compound C or AMPK siRNA reduced CSE-induced IL-8 production, confirming the role of AMPK. Compound C or AMPK siRNA also inhibited the activation of MAPKs and NF-κB by CSE, which suggests that these molecules are downstream of AMPK. Additionally, exposure of human macrophages to nicotine activated AMPK and induced IL-8 and that these effects were lessened by hexamethonium or compound C, implying that nicotine in CS may be causative. Furthermore, chronic CS exposure in mice promoted AMPK phosphorylation and expression of MIP-2 (an IL-8 homolog) in infiltrated macrophages and in lung tissues, as well as induced lung inflammation, all of which were reduced by compound C treatment. Thus, we identified a novel nAChRs-dependent, ROS-sensitive, AMPK/MAPKs/NF-κB signaling pathway, which seems to be important to CS-induced macrophage IL-8 production and possibly to lung inflammation.
吸入香烟烟雾（CS）会导致吸烟者肺部持续发炎。巨噬细胞释放的白细胞介素8（IL-8）是CS诱导的肺部炎症起始和进展过程中的关键趋化因子，但其调控机制在很大程度上尚不清楚。AMP激活的蛋白激酶（AMPK）是一种关键的能量稳态调节因子，可能会调节炎症。在此，我们报告CS提取物（CSE）可增加人类巨噬细胞内活性氧（ROS）水平，激活AMPK、丝裂原活化蛋白激酶（MAPK）和核因子κB（NF-κB），并诱导IL-8。N-乙酰半胱氨酸（ROS清除剂）或六甲铵[烟碱型乙酰胆碱受体（nAChR）拮抗剂]可减弱CSE诱导的细胞内ROS增加、AMPK和NF-κB的激活以及IL-8的诱导，这表明nAChR和ROS很重要。用化合物C或AMPK小干扰RNA（siRNA）阻止AMPK激活可减少CSE诱导的IL-8产生，证实了AMPK的作用。化合物C或AMPK siRNA也抑制了CSE对MAPK和NF-κB的激活，这表明这些分子位于AMPK的下游。此外，人类巨噬细胞暴露于尼古丁会激活AMPK并诱导IL-8，而六甲铵或化合物C可减轻这些作用，这意味着CS中的尼古丁可能是病因。此外，小鼠长期暴露于CS会促进浸润巨噬细胞和肺组织中AMPK磷酸化和MIP-2（一种IL-8同源物）的表达，并诱导肺部炎症，而化合物C处理可减轻所有这些情况。因此，我们确定了一条新的nAChR依赖性、ROS敏感性的AMPK/MAPK/NF-κB信号通路，该通路似乎对CS诱导的巨噬细胞IL-8产生以及可能对肺部炎症很重要。
