title: Co-culture of healthy human keratinocytes and T-cells promotes keratinocyte chemokine production and RORγt-positive IL-17 producing T-cell populations.
abstract: BACKGROUND
  Both keratinocytes and T-cells are crucial players in cutaneous immune responses. We hypothesized that direct interactions between keratinocytes and T-cell subsets could shape the nature or strength of the local immune response.
  
  
  OBJECTIVE
  We investigated direct interactions between keratinocytes and T-cell subsets, focused on keratinocyte chemokine production and T-cell phenotype and cytokine production.
  
  
  METHODS
  A newly developed in vitro serum free co-culture model using primary keratinocytes and T-cells subsets from healthy human donors was used. Keratinocyte chemokine production was analyzed with luminex, T-cell phenotype and cytokine production were analyzed with flow cytometry.
  
  
  RESULTS
  Our data show that upon co-culture with CD4(pos) or CD8(pos) T-cells primary human keratinocytes increased production of functionally active chemokines CCL2, CCL20 and CXCL10 and that regulatory T-cells did not regulate keratinocyte chemokine production. Next to that, we found that keratinocytes skewed CD4(pos) and CD8(pos) T-cell populations toward an IL-17(pos) CCR6(pos) RORγt(pos) phenotype in a cell-cell contact independent manner, and that Treg were able to decrease the absolute number of IL-17 producing T-cells in keratinocyte/T-cell co-cultures. Correspondingly, freshly isolated skin-derived T-cell populations contained relatively high percentages of IL-17(pos) cells.
  
  
  CONCLUSIONS
  We provide evidence that keratinocyte/T-cell communication may regulate leukocyte influx in the skin, and that keratinocytes enrich T-cell populations for Th17/Tc17 cells. Accumulation of Th17/Tc17 cells, but not chemokine production, appears under the control of regulatory T-cells. Dysregulation of these processes may well contribute to the pathophysiology of inflammatory skin diseases.
authors.affiliation: Department of Laboratory Medicine - Medical Immunology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Jorieke H
authors.initials: JH
authors.lastname: Peters
authors.forename: Geuranne S
authors.initials: GS
authors.lastname: Tjabringa
authors.forename: Esther
authors.initials: E
authors.lastname: Fasse
authors.forename: Vivian L
authors.initials: VL
authors.lastname: de Oliveira
authors.forename: Joost
authors.initials: J
authors.lastname: Schalkwijk
authors.forename: Hans J P M
authors.initials: HJ
authors.lastname: Koenen
authors.forename: Irma
authors.initials: I
authors.lastname: Joosten
mesh_terms: D000704:Analysis of Variance; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002450:Cell Communication; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D054418:Chemokine CCL20 / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000378:metabolism; D018920:Coculture Techniques; D005347:Fibroblasts / Q000276:immunology; D006801:Humans; D015603:Keratinocytes / Q000276:immunology* / Q000378:metabolism*; D057132:Nuclear Receptor Subfamily 1, Group F, Member 3; D010641:Phenotype; D012867:Skin / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology / Q000378:metabolism
chemical_list: D018932:Chemokine CCL2; D054418:Chemokine CCL20; D054357:Chemokine CXCL10; D057132:Nuclear Receptor Subfamily 1, Group F, Member 3