title: Characterization of the inflammatory infiltrate and cytokine expression in the skin of horses with recurrent urticaria.
abstract: BACKGROUND
  Recurrent urticaria (RU) is a common skin disease of horses, but little is known about its pathogenesis.
  
  
  OBJECTIVE
  The aim of this study was to characterize the inflammatory cell infiltrate and cytokine expression pattern in the skin of horses with RU.
  
  
  METHODS
  Biopsies of lesional and nonlesional skin of horses with RU (n = 8) and of skin from healthy control horses (n = 8) were evaluated.
  
  
  METHODS
  The inflammatory cell infiltrate was analysed by routine histology. Immunohistochemistry was used to identify T cells (CD3), B  ells (CD79), macrophages (MAC387) and mast cells (tryptase). Expression of T-helper 2 cytokines (interleukins IL-4, IL-5 and IL-13), a T-helper 1 cytokine (interferon-γ), IL-4 receptor α and thymic stromal lymphopoietin was assessed by quantitative RT-PCR. Results -  In subepidermal lesional skin of RU-affected horses, increased numbers of eosinophils (P ≤ 0.01), CD79-positive (P ≤ 0.01), MAC387-positive (P ≤ 0.01) and tryptase-positive cells (P ≤ 0.05) were found compared with healthy horses. Subepidermal lesional skin of RU-affected horses contained more eosinophils (P ≤ 0.05) and tryptase-positive cells (P ≤ 0.05) compared with nonlesional skin. There was no significant difference in infiltrating cells between nonlesional skin and skin of healthy horses. Expression of IL-4 (P ≤ 0.01), IL-13 (P ≤ 0.05), thymic stromal lymphopoietin (P ≤ 0.05) and IL-4 receptor α (P ≤ 0.05) was increased in lesional skin of RU-affected horses compared with control horses. Expression of IL-4 was higher (P ≤ 0.05) in lesional compared with nonlesional RU skin.
  
  
  CONCLUSIONS
  Analysis of cytokine expression and inflammatory infiltrate suggests that T-helper 2 cytokines, eosinophils, mast cells and presumptive macrophages play a role in the pathogenesis of equine RU.
authors.affiliation: Division of Clinical Dermatology, Department of Clinical Research-Veterinary Public Health, University of Bern, Bern, Switzerland.
authors.forename: Sandro
authors.initials: S
authors.lastname: Hinden
authors.forename: Jolanta
authors.initials: J
authors.lastname: Klukowska-Rötzler
authors.forename: Jozef
authors.initials: J
authors.lastname: Janda
authors.forename: Eliane I
authors.initials: EI
authors.lastname: Marti
authors.forename: Vinzenz
authors.initials: V
authors.lastname: Gerber
authors.forename: Petra J
authors.initials: PJ
authors.lastname: Roosje
mesh_terms: D000818:Animals; D016022:Case-Control Studies; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000276:immunology; D006734:Horse Diseases / Q000378:metabolism* / Q000473:pathology; D006736:Horses; D007249:Inflammation; D012867:Skin / Q000166:cytology* / Q000378:metabolism*; D059467:Transcriptome; D014581:Urticaria / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*
chemical_list: D016207:Cytokines