Circulating CD4(+)CD25(+)Foxp3(+) T regulatory cell levels in an experimental model of canine atopic dermatitis

BACKGROUND: The pathogenesis of canine atopic dermatitis (cAD) is characterized immunologically by an imbalanced T-cell response. Mechanisms of immune regulation in cAD have not yet been completely elucidated. OBJECTIVES: To investigate peripheral blood T regulatory (Treg) cells and their associated cytokines (TGF-β and IL-10) in an experimental model of cAD. ANIMALS: Eight beagle dogs that were initially naïve and subsequently sensitized to house dust mites (HDM). METHODS AND MATERIALS: T regulatory cell phenotyping was performed by flow-cytometric analysis on peripheral blood; serum cytokine levels were measured by ELISA, before sensitization and after challenge with HDM allergens. Additionally, clinical scores and allergen-specific IgE were determined. RESULTS: After challenge of sensitized dogs to HDM allergen, a significant increase of Treg cells and simultaneous decrease in the serum TGF-β were observed. However, in most dogs, serum IL-10 values were below the detection limit. Treg cell proportions before sensitization were significantly negatively correlated with the HDM-specific IgE levels and clinical scores after induction of AD signs. CONCLUSION AND CLINICAL IMPORTANCE: The results confirm that Treg responses are involved in the pathogenesis of an experimental model cAD. Further investigations are required to clarify the precise immune modulating function of canine Treg cells and their interplay with other immune cell types