Toward a canine model of atopic dermatitis: amplification of cytokine-gene transcripts in the skin of atopic dogs

The objectives of the present study were to characterize and compare the repertoire of cytokine-genes transcribed in skin homogenates obtained from normal dogs and dogs with atopic dermatitis (AD) using a reverse-transcriptase polymerase chain reaction and canine-specific cytokine-gene primers. Whereas IL-4 and IL-5 cytokine-gene transcripts were detected more commonly in atopic skin biopsy homogenates, IL-2 mRNA was amplified more often from normal control specimens. IFN-gamma mRNA was detected in 5/29 atopic specimens, 4 of them obtained from the only dog with chronic skin lesions. One-fourth of atopic samples exhibited clear type-2 cytokine profiles; the remainder did not demonstrate polarized repertoires. Conversely, type-1 cytokine profiles were characterized in one-fourth of normal control specimens. The present study establishes, for the first time, the transcription of type-2 cytokine-genes in the skin of dogs with AD. Future experiments investigating the cellular origin and dynamics of allergic cytokine-gene transcription are needed to confirm whether or not canine AD could be considered an immunological model for a human disease.