title: Aryl hydrocarbon receptor-ligand axis mediates pulmonary fibroblast migration and differentiation through increased arachidonic acid metabolism.
abstract: Pulmonary fibroblast migration and differentiation are critical events in fibrogenesis; meanwhile, fibrosis characterizes the pathology of many respiratory diseases. The role of aryl hydrocarbon receptor (AhR), a unique cellular chemical sensor, has been suggested in tissue fibrosis, but the mechanisms through which the AhR-ligand axis influences the fibrotic process remain undefined. In this study, the potential impact of the AhR-ligand axis on pulmonary fibroblast migration and differentiation was analyzed using human primary lung fibroblasts HFL-1 and CCL-202 cells. Boyden chamber-based cell migration assay showed that activated AhR in HFL-1cells significantly enhanced cell migration in response to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), and a known AhR antagonist, CH223191, inhibited its migratory activity. Furthermore, the calcium mobilization and subsequent upregulated expression of arachidonic acid metabolizing enzymes, including cyclooxygenase2 (COX-2) and 5-lipoxygenase (5-LOX), were observed in TCDD-treated HFL-1 cells, concomitant with elevated levels of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) secretion. Also, significantly increased expression of α-smooth muscle actin α-SMA), a fibroblast differentiation marker, was also noted in TCDD-treated HFL-1 cells (p<0.05), resulting in a dynamic change in cytoskeleton protein levels and an increase in the nuclear translocation of the myocardin-related transcription factor. Moreover, the enhanced levels of α-SMA expression and fibroblast migration induced by TCDD, PGE2 and LTB4 were abrogated by selective inhibitors for COX-2 and 5-LOX. Knockdown of AhR by siRNA completely diminished intracellular calcium uptake and reduced α-SMA protein verified by promoter-reporter assays and chromatin immunoprecipitation. Taken together, our results suggested the importance of the AhR-ligand axis in fibroblast migration and differentiation through its capacity in enhancing arachidonic acid metabolism.
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hsiang-Han
authors.initials: HH
authors.lastname: Su
authors.affiliation: Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Taiwan.
authors.forename: Hsin-Ting
authors.initials: HT
authors.lastname: Lin
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Center for Research Resources and Development, Kaohsiung Medical University, Taiwan.
authors.forename: Jau-Ling
authors.initials: JL
authors.lastname: Suen
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Internal Medicine, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chau Chyun
authors.initials: CC
authors.lastname: Sheu
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung, Taiwan; Center for Infectious Diseases and Cancer, Kaohsiung Medical University, Kaohsiung, Taiwan; Faculty of Science and Engineering, Department of Pharmacological Science, Tokushima Bunri University, Sanuki, Japan; Department of Molecular Prevention Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Kazunari K
authors.initials: KK
authors.lastname: Yokoyama
authors.affiliation: Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli County, Taiwan. Electronic address: skhuang@nhri.org.tw.
authors.forename: Shau-Ku
authors.initials: SK
authors.lastname: Huang
authors.affiliation: Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: chmech@kmu.edu.tw.
authors.forename: Chih Mei
authors.initials: CM
authors.lastname: Cheng
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D001094:Arachidonate 5-Lipoxygenase / Q000235:genetics / Q000378:metabolism; D001095:Arachidonic Acids / Q000378:metabolism*; D001391:Azo Compounds / Q000633:toxicity; D002454:Cell Differentiation; D002460:Cell Line; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D007975:Leukotriene B4 / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011401:Promoter Regions, Genetic; D011720:Pyrazoles / Q000633:toxicity; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: C511621:2-methyl-2H-pyrazole-3-carboxylic acid (2-methyl-4-o-tolylazophenyl)amide; C541116:ACTA2 protein, human; D000199:Actins; D001095:Arachidonic Acids; D001391:Azo Compounds; D000072317:Polychlorinated Dibenzodioxins; D011720:Pyrazoles; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; D007975:Leukotriene B4; D001094:Arachidonate 5-Lipoxygenase; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C583212:ALOX5 protein, human; D015232:Dinoprostone
keywords: Alpha-SMA; Arachidonic acid; Aryl hydrocarbon receptor; Fibrosis; Myocardin-related transcription factor