title: Lipopolysaccharide induces ICAM-1 expression via a c-Src/NADPH oxidase/ROS-dependent NF-κB pathway in human pulmonary alveolar epithelial cells.
abstract: Upregulation of intercellular adhesion molecule-1 (ICAM-1) is frequently implicated in lung inflammation. Lipopolysaccharide (LPS) has been shown to play a key role in inflammation via adhesion molecule induction and then causes lung injury. However, the mechanisms underlying LPS-induced ICAM-1 expression in human pulmonary alveolar epithelial cells (HPAEpiCs) remain unclear. We showed that LPS induced ICAM-1 expression in HPAEpiCs, revealed by Western blotting, RT-PCR, real-time PCR, and promoter assay. Pretreatment with the inhibitor of c-Src (protein phosphatase-1, PP1), reactive oxygen species (ROS) (Edaravone), NADPH oxidase (apocynin and diphenyleneiodonium chloride), EGFR (AG1478), PDGFR (AG1296), phosphatidylinositol-3-kinase (PI3K) (LY294002), MEK1/2 (U0126), or NF-κB (Bay11-7082) and transfection with siRNAs of c-Src, EGFR, PDGFR, Akt, p47(phox), Nox2, Nox4, p42, and p65 markedly reduced LPS-induced ICAM-1 expression and monocyte adherence to HPAEpiCs challenged with LPS. In addition, we established that LPS stimulated phosphorylation of c-Src, EGFR, PDGFR, Akt, or p65, which was inhibited by pretreatment with their respective inhibitors. LPS induced Toll-like receptor 4 (TLR4), MyD88, TNF receptor-associated factor 6 (TRAF6), c-Src, p47(phox), and Rac1 complex formation 2, which was attenuated by transfection with c-Src or TRAF6 siRNA. Furthermore, LPS markedly enhanced NADPH oxidase activation and intracellular ROS generation, which were inhibited by PP1. We established that LPS induced p42/p44 MAPK activation via a c-Src/NADPH oxidase/ROS/EGFR, PDGFR/PI3K/Akt-dependent pathway in these cells. Finally, we observed that LPS significantly enhanced NF-κB and IκBα phosphorylation, NF-κB translocation, and NF-κB promoter activity, which were inhibited by PP1, Edaravone, apocynin, diphenyleneiodonium chloride, AG1478, AG1296, LY294002, or U0126. These results demonstrated that LPS induces p42/p44 MAPK activation mediated through the TLR4/MyD88/TRAF6/c-Src/NADPH oxidase/ROS/EGFR, PDGFR/PI3K/Akt pathway, which in turn initiates the activation of NF-κB and ultimately induces ICAM-1 expression in HPAEpiCs.
authors.affiliation: Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan;
authors.forename: Rou-Ling
authors.initials: RL
authors.lastname: Cho
authors.affiliation: Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan; Department of Traditional Chinese Medicine, Chang Gung Memorial Hospital at Lin-Kou, Kwei-San, Tao-Yuan, Taiwan;
authors.forename: Chien-Chung
authors.initials: CC
authors.lastname: Yang
authors.affiliation: Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan;
authors.forename: I-Ta
authors.initials: IT
authors.lastname: Lee
authors.affiliation: Department of Anesthetics, Chang Gung Memorial Hospital at Lin-Kou and College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan;
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan;
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Chi
authors.affiliation: Department of Anesthetics, Chang Gung Memorial Hospital at Lin-Kou and College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan;
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
authors.affiliation: Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan; Department of Anesthetics, Chang Gung Memorial Hospital at Lin-Kou and College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan; Research Center for Industry of Human Ecology and Graduate Institute of Health Industry Technology, Chang Gung University of Science and Technology, Tao-Yuan, Taiwan chuenmao@mail.cgu.edu.tw.
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
mesh_terms: D056809:Alveolar Epithelial Cells / Q000276:immunology / Q000378:metabolism*; D000081247:CSK Tyrosine-Protein Kinase; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D008168:Lung / Q000276:immunology / Q000473:pathology; D019255:NADPH Oxidases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000378:metabolism; D015533:Transcriptional Activation / Q000276:immunology; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D000081247:CSK Tyrosine-Protein Kinase; D066246:ErbB Receptors; D018799:Intercellular Adhesion Molecule-1; D008070:Lipopolysaccharides; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D017479:Receptors, Platelet-Derived Growth Factor; D051996:Transcription Factor RelA; D019061:src-Family Kinases; C498143:RELA protein, human; C512478:EGFR protein, human; C000631346:CSK protein, human
keywords: adhesion molecules; lipopolysaccharide; lung inflammation; signaling pathway; transcription factor