title: CD4+ and CD8+ skin-associated T lymphocytes in canine atopic dermatitis produce interleukin-13, interleukin-22 and interferon-γ and contain a CD25+ FoxP3+ subset.
abstract: BACKGROUND
  T Cells play a major role in the immunopathogenesis of canine atopic dermatitis (cAD). However, the significance of cutaneous regulatory T cells (Tregs) and CD8(+) T cells is currently unclear.
  
  
  OBJECTIVE
  The study aimed to evaluate the presence and distribution of Tregs in cAD and healthy skin and to determine the cytokine production of cutaneous CD4(+) and CD8(+) T cells.
  
  
  METHODS
  Biopsies were taken from four dogs with cAD (lesional and nonlesional skin) and four healthy control dogs.
  
  
  METHODS
  Distribution patterns of T-cell subtypes in cAD lesional, nonlesional and control skin were evaluated by immunohistochemistry. Phenotypic characterization of T cells from skin explant cultures and enzymatic digestions was performed using flow cytometry. Cytokine production of sorted CD4(+) and CD8(+) explant-derived T cells was measured by RT-qPCR.
  
  
  RESULTS
  Regulatory T cells phenotypically characterized by CD25(+) FoxP3(+) were found in both CD4(+) and CD8(+) subsets of skin explant and digestion samples. The percentages of CD4(+) CD25(+) cells that were FoxP3(+) were similar in cAD and control skin. In atopic lesional and nonlesional explant samples, lower FoxP3(+) percentages of CD8(+) CD25(+) cells were seen compared with control skin. The presence of predominantly periadnexal CD25(+) FoxP3(+) cells was confirmed by immunohistochemistry in lesional, nonlesional and control skin. The CD4(+) /CD8(+) ratio was less than one in cAD skin with both skin explant and digestion methods. CD4(+) and CD8(+) T-cell subsets of lesional and nonlesional cAD skin were capable of producing interleukin-13, interleukin-22 and interferon-γ.
  
  
  CONCLUSIONS
  Both CD4(+) and CD8(+) T cells are likely to contribute to the immunopathogenesis of cAD through the production of interleukin-13, interleukin-22 and interferon-γ. In both subsets, functional analysis of FoxP3(+) cells is essential to determine their role.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 108, 3584 CM, Utrecht, The Netherlands.
authors.forename: Annette
authors.initials: A
authors.lastname: Jassies-van der Lee
authors.forename: Victor P M G
authors.initials: VP
authors.lastname: Rutten
authors.forename: Jet
authors.initials: J
authors.lastname: Bruijn
authors.forename: Ton
authors.initials: T
authors.lastname: Willemse
authors.forename: Femke
authors.initials: F
authors.lastname: Broere
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology*; D002478:Cells, Cultured; D003876:Dermatitis, Atopic / Q000276:immunology / Q000662:veterinary*; D004283:Dog Diseases / Q000276:immunology*; D004285:Dogs; D005434:Flow Cytometry / Q000662:veterinary; D051858:Forkhead Transcription Factors / Q000276:immunology / Q000502:physiology*; D007371:Interferon-gamma / Q000502:physiology*; D018793:Interleukin-13 / Q000502:physiology*; D007376:Interleukin-2 / Q000502:physiology*; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012867:Skin / Q000166:cytology* / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000502:physiology*
chemical_list: D051858:Forkhead Transcription Factors; D018793:Interleukin-13; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D007371:Interferon-gamma