Evaluation of Th₁‐like, Th₂‐like and immunomodulatory cytokine mRNA expression in the skin of dogs with immunomodulatory‐responsive lymphocytic–plasmacytic pododermatitis

Abstract

The term immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis (ImR-LPP) has previously been proposed to denote a subpopulation of dogs with idiopathic pododermatitis. The objective of this study was to quantify the expression of mRNA encoding Th(1)-like [interferon (IFN)-gamma, interleukin (IL)-2 and IL-12], Th(2)-like [IL-4 and IL-6] and immunomodulatory cytokines [IL-10 and transforming growth factor (TGF)-beta] in lesional ImR-LPP, nonlesional ImR-LPP and healthy control pedal skin. Gene transcripts were quantified using TaqMan real-time reverse transcriptase-polymerase chain reaction assays. The skin of dogs with ImR-LPP had significant overexpression of IL-6 mRNA (P < 0.05) and significant underexpression of IL-12 mRNA (P < 0.01) compared to healthy controls. In addition, lesional ImR-LPP skin had significantly higher levels of IL-10 transcripts compared to healthy control pedal skin (P < 0.05). Although not attaining significance (P = 0.07), a trend towards reduced TGF-beta mRNA expression in lesional ImR-LPP skin was also evident. There were no significant differences in the levels of IFN-gamma or IL-2 mRNA transcripts among the three skin sample sources. IL-4 mRNA was detected in only one lesional sample. These results suggest that the pathogenesis of ImR-LPP may be associated with a T-cell-mediated inflammatory response characterized by impaired Th(1)-like, but enhanced Th(2)-like cytokine expression.