title: Requirement of CCL17 for CCR7- and CXCR4-dependent migration of cutaneous dendritic cells.
abstract: Chemokines are known to regulate the steady-state and inflammatory migration of cutaneous dendritic cells (DCs). The beta-chemokine CCL17, a ligand of CCR4, is inducibly expressed in a subset of DCs and is strongly up-regulated in atopic diseases. Using an atopic dermatitis model, we show that CCL17-deficient mice develop acanthosis as WT mice, whereas dermal inflammation, T helper 2-type cytokine production, and the allergen-specific humoral immune response are significantly decreased. Notably, CCL17-deficient mice retained Langerhans cells (LCs) in the lesional skin after chronic allergen exposure, whereas most LCs emigrated from the epidermis of allergen-treated WT controls into draining lymph nodes (LNs). Moreover, CCL17-deficient LCs showed impaired emigration from the skin after exposure to a contact sensitizer. In contrast, the absence of CCR4 had no effect on cutaneous DC migration and development of atopic dermatitis symptoms. As an explanation for the major migratory defect of CCL17-deficient DCs in vivo, we demonstrate impaired mobility of CCL17-deficient DCs to CCL19/21 in 3D in vitro migration assays and a blockade of intracellular calcium release in response to CCR7 ligands. In addition, responsiveness of CCL17-deficient DCs to CXCL12 was impaired as well. We demonstrate that the inducible chemokine CCL17 sensitizes DCs for CCR7- and CXCR4-dependent migration to LN-associated homeostatic chemokines under inflammatory conditions and thus plays an important role in cutaneous DC migration.
authors.affiliation: Molecular Immunology, Leibniz Institut fuer Umweltmedizinische Forschung, Düsseldorf, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Stutte
authors.forename: Thomas
authors.initials: T
authors.lastname: Quast
authors.forename: Nancy
authors.initials: N
authors.lastname: Gerbitzki
authors.forename: Terhi
authors.initials: T
authors.lastname: Savinko
authors.forename: Nina
authors.initials: N
authors.lastname: Novak
authors.forename: Julia
authors.initials: J
authors.lastname: Reifenberger
authors.forename: Bernhard
authors.initials: B
authors.lastname: Homey
authors.forename: Waldemar
authors.initials: W
authors.lastname: Kolanus
authors.forename: Harri
authors.initials: H
authors.lastname: Alenius
authors.forename: Irmgard
authors.initials: I
authors.lastname: Förster
mesh_terms: D000485:Allergens / Q000276:immunology; D000818:Animals; D002465:Cell Movement / Q000276:immunology*; D054414:Chemokine CCL17 / Q000172:deficiency / Q000378:metabolism*; D003877:Dermatitis, Contact / Q000276:immunology; D020405:Dermis / Q000276:immunology / Q000473:pathology; D056724:Immunity, Humoral / Q000276:immunology; D007249:Inflammation / Q000276:immunology / Q000473:pathology; D007801:Langerhans Cells / Q000276:immunology / Q000473:pathology*; D008024:Ligands; D051379:Mice; D054400:Receptors, CCR7 / Q000378:metabolism*; D019718:Receptors, CXCR4 / Q000378:metabolism*
chemical_list: D000485:Allergens; C514936:CXCR4 protein, mouse; C499538:Ccl17 protein, mouse; C515371:Ccr7 protein, mouse; D054414:Chemokine CCL17; D008024:Ligands; D054400:Receptors, CCR7; D019718:Receptors, CXCR4