title: Sphingosine 1-Phosphate-Induced ICAM-1 Expression via NADPH Oxidase/ROS-Dependent NF-κB Cascade on Human Pulmonary Alveolar Epithelial Cells.
abstract: The intercellular adhesion molecule-1 (ICAM-1) expression is frequently correlated with the lung inflammation. In lung injury, sphingosine-1-phosphate (S1P, bioactive sphingolipid metabolite), participate gene regulation of adhesion molecule in inflammation progression and aggravate tissue damage. To investigate the transduction mechanisms of the S1P in pulmonary epithelium, we demonstrated that exposure of HPAEpiCs (human pulmonary alveolar epithelial cells) to S1P significantly induces ICAM-1 expression leading to increase monocyte adhesion on the surface of HPAEpiCs. These phenomena were effectively attenuated by pretreatments with series of inhibitors such as Rottlerin (PKCδ), PF431396 (PYK2), diphenyleneiodonium chloride (DPI), apocynin (NADPH oxidase), Edaravone (ROS), and Bay11-7082 (NF-κB). Consistently, knockdown with siRNA transfection of PKCδ, PYK2, p47 (phox) , and p65 exhibited the same results. Pretreatment with both Gq-coupled receptor antagonist (GPA2A) and Gi/o-coupled receptor antagonist (GPA2) also blocked the upregulation of ICAM-1 protein and mRNA induced by S1P. We observed that S1P induced PYK2 activation via a Gq-coupled receptor/PKCδ-dependent pathway. In addition, S1P induced NADPH oxidase activation and intracellular ROS generation, which were also reduced by Rottlerin or PF431396. We demonstrated that S1P induced NF-κB p65 phosphorylation and nuclear translocation in HPAEpiCs. Activated NF-κB was blocked by Rottlerin, PF431396, APO, DPI, or Edaravone. Besides, the results of monocyte adhesion assay indicated that S1P-induced ICAM-1 expression on HPAEpiCs can enhance the monocyte attachments. In the S1P-treated mice, we found that the levels of ICAM-1 protein and mRNA in the lung fractions, the pulmonary hematoma and leukocyte count in bronchoalveolar lavage fluid were enhanced through a PKCδ/PYK2/NADPH oxidase/ROS/NF-κB signaling pathway. We concluded that S1P-accelerated lung damage is due to the ICAM-1 induction associated with leukocyte recruitment.
authors.affiliation: Department of Anesthetics, Chang Gung Memorial Hospital at LinkouTaoyuan, Taiwan; College of Medicine, Chang Gung UniversityTaoyuan, 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 UniversityTaoyuan, Taiwan; Department of Traditional Chinese Medicine, Chang Gung Memorial Hospital at LinkouTaoyuan, 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 Taoyuan, Taiwan.
authors.forename: Rou-Ling
authors.initials: RL
authors.lastname: Cho
authors.affiliation: Department of Anesthetics, Chang Gung Memorial Hospital at LinkouTaoyuan, Taiwan; College of Medicine, Chang Gung UniversityTaoyuan, Taiwan.
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Department of Anesthetics, Chang Gung Memorial Hospital at LinkouTaoyuan, Taiwan; College of Medicine, Chang Gung UniversityTaoyuan, Taiwan.
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
authors.affiliation: Department of Anesthetics, Chang Gung Memorial Hospital at LinkouTaoyuan, Taiwan; College of Medicine, Chang Gung UniversityTaoyuan, Taiwan; Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung UniversityTaoyuan, Taiwan; Research Center for Industry of Human Ecology and Graduate Institute of Health Industry Technology, Chang Gung University of Science and TechnologyTaoyuan, Taiwan.
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
keywords: intercellular adhesion molecule-1; lung inflammation; monocyte adhesion; sphingosine-1-phosphate; transcription factor