title: The role of the Th2 CC chemokine ligand CCL17 in pulmonary fibrosis.
abstract: Increasing evidence suggests that the development of pulmonary fibrosis is a Th2-mediated process. We hypothesized that the CC chemokines that are associated with a Th2 profile (CCL17 and CCL22) have an important role in the development of pulmonary fibrosis. We measured CCL17 and CCL22 during the pathogenesis of bleomycin-induced pulmonary fibrosis. We found that both CCL17 and CCL22 were significantly elevated through day 20 as compared with control mice. Peak expression of CCL22 preceded the peak levels of CCL17, as measured by real-time quantitative PCR. CCR4 is the receptor for CCL17 and CCL22 therefore, to further characterize the role of CCL17 and CCL22, we measured CCR4 mRNA in lung tissue of bleomycin-treated mice by real-time quantitative PCR. CCR4 was significantly elevated in bleomycin-treated mice as compared with control mice. Immunolocalization demonstrated that CCR4 was expressed predominantly on macrophages. Neutralization of CCL17, but not CCL22, led to a reduction in pulmonary fibrosis. Immunolocalization of bleomycin-treated lung tissue and human idiopathic pulmonary fibrosis tissue specimens showed that epithelial cells expressed CCL17. These findings demonstrate a central role for Th2 chemokines and the macrophage in the pathogenesis of pulmonary fibrosis and are further support for the role of a Th2 phenotype in the pathogenesis of pulmonary fibrosis.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Belperio
authors.forename: Maria
authors.initials: M
authors.lastname: Dy
authors.forename: Lynne
authors.initials: L
authors.lastname: Murray
authors.forename: Marie D
authors.initials: MD
authors.lastname: Burdick
authors.forename: Ying Y
authors.initials: YY
authors.lastname: Xue
authors.forename: Robert M
authors.initials: RM
authors.lastname: Strieter
authors.forename: Michael P
authors.initials: MP
authors.lastname: Keane
mesh_terms: D000818:Animals; D001761:Bleomycin / Q000008:administration & dosage / Q000494:pharmacology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002460:Cell Line; D002465:Cell Movement / Q000276:immunology; D054414:Chemokine CCL17; D054422:Chemokine CCL22; D019742:Chemokines, CC / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000276:immunology / Q000473:pathology; D006801:Humans; D007116:Immunization, Passive; D007958:Leukocyte Count; D008024:Ligands; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008808:Mice, Inbred CBA; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D054398:Receptors, CCR4; D019707:Receptors, Chemokine / Q000096:biosynthesis; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism*
chemical_list: C106230:CCL17 protein, human; C515482:CCL22 protein, human; C515354:CCR4 protein, human; C499538:Ccl17 protein, mouse; C515483:Ccl22 protein, mouse; C515355:Ccr4 protein, mouse; D054414:Chemokine CCL17; D054422:Chemokine CCL22; D019742:Chemokines, CC; D008024:Ligands; D054398:Receptors, CCR4; D019707:Receptors, Chemokine; D001761:Bleomycin