title: The CCR6/CCL20 axis mediates Th17 cell migration to the ocular surface in dry eye disease.
abstract: OBJECTIVE
  Th17 cells are believed to be the primary effector cells in the pathogenesis of dry eye disease (DED). However, the mechanisms by which Th17 cells migrate from the lymphoid tissues to the ocular surface are unknown. The purpose of this study was to investigate the role of the C-C chemokine receptor 6/C-C chemokine ligand 20 (CCR6/CCL20) chemokine axis in mediating Th17 cell migration in DED.
  
  
  METHODS
  DED was induced by housing C57BL/6 mice in a low-humidity environment supplemented with scopolamine treatment. Th17 cell expression of CCR6 was evaluated using flow cytometry and ocular surface expression of CCL20 was measured using PCR and ELISA assays. CCL20 neutralizing antibody was administered subconjunctivally to DED mice and disease severity, including the frequency of conjunctival Th17 cells, was evaluated.
  
  
  RESULTS
  CCR6 is preferentially expressed by Th17 cells in both normal and DED mice and DED significantly upregulates ocular surface expression of CCL20. Disruption of CCR6/CCL20 binding with CCL20 neutralizing antibody decreases T-cell migration in vitro and reduces Th17 cell infiltration of the conjunctiva when administered in vivo, significantly improving clinical signs of DED. These changes were accompanied by a decrease in ocular surface inflammatory cytokine levels and corneal CD11b+ cell frequencies. Treatment also significantly reduced the generation of Th17 cells.
  
  
  CONCLUSIONS
  Local neutralization of CCL20 decreases Th17 cell infiltration of the ocular surface in DED, leading to improvement in clinical signs of disease. This suggests that CCR6/CCL20 interactions direct Th17 cell migration in DED and that disruption of this axis may be a novel therapeutic approach to this condition.
authors.affiliation: Schepens Eye Research Institute and Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Dohlman
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Chauhan
authors.forename: Shilpa
authors.initials: S
authors.lastname: Kodati
authors.forename: Jing
authors.initials: J
authors.lastname: Hua
authors.forename: Yihe
authors.initials: Y
authors.lastname: Chen
authors.forename: Masahiro
authors.initials: M
authors.lastname: Omoto
authors.forename: Zahra
authors.initials: Z
authors.lastname: Sadrai
authors.forename: Reza
authors.initials: R
authors.lastname: Dana
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing; D002465:Cell Movement / Q000502:physiology*; D054418:Chemokine CCL20 / Q000378:metabolism*; D004195:Disease Models, Animal; D015352:Dry Eye Syndromes / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D051379:Mice; D008810:Mice, Inbred C57BL; D060888:Real-Time Polymerase Chain Reaction; D054399:Receptors, CCR6 / Q000378:metabolism*; D012601:Scopolamine / Q000633:toxicity; D058504:Th17 Cells / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; C493447:CCL20 protein, mouse; C498126:CCR6 protein, mouse; D054418:Chemokine CCL20; D054399:Receptors, CCR6; D012601:Scopolamine
keywords: CCL20; CCR6; Th17 cell; cell migration; dry eye