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Expression of Th1, Th2 and immunosuppressive cytokine gene transcripts in canine atopic dermatitis

Authors

  • T. J. Nuttall,

    1. University of Edinburgh Department of Veterinary Clinical Science, Hospital for Small Animals, Easter Bush Veterinary Centre, Easter Bush, Midlothian, and
    2. Immunobiology Group, MRC Centre for Inflammation Research, University of Edinburgh Medical School, Edinburgh, UK
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  • P. A. Knight,

    1. University of Edinburgh Department of Veterinary Clinical Science, Hospital for Small Animals, Easter Bush Veterinary Centre, Easter Bush, Midlothian, and
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  • S. M. McAleese,

    1. University of Edinburgh Department of Veterinary Clinical Science, Hospital for Small Animals, Easter Bush Veterinary Centre, Easter Bush, Midlothian, and
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  • J. R. Lamb,

    1. Immunobiology Group, MRC Centre for Inflammation Research, University of Edinburgh Medical School, Edinburgh, UK
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  • P. B. Hill

    1. University of Edinburgh Department of Veterinary Clinical Science, Hospital for Small Animals, Easter Bush Veterinary Centre, Easter Bush, Midlothian, and
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Correspondence:Tim Nuttall, University of Liverpool Small Animal Hospital, Crown Street, Liverpool, Merseyside L7 7EX, UK. E-mail: timn@liv.ac.uk

Summary

Background Atopic dermatitis is a common inflammatory skin disease of humans and dogs. Human atopic dermatitis is associated with Th2-type responses, although Th1 cytokines can be identified in chronic lesions. In contrast, tolerance to environmental allergens in healthy individuals is mediated by regulatory T cells.

Objective This study examined the expression of the immunosuppressive cytokines TGF-β and IL-10, the Th2-type cytokines IL-4 and IL-6, and the Th1-type cytokines IFN-γ, TNF-α, IL-2, IL-12p35 and IL-12p40, in canine atopic dermatitis.

Materials and methods RNA was isolated from lesional atopic, non-lesional atopic and healthy canine skin samples. Semi-quantitative reverse transcriptase polymerase chain reactions (RT-PCRs) were carried out using specific primers and one-way analyses of variance used to compare cytokine expression in each group.

Results Canine atopic dermatitis was associated with over-expression of IL-4 mRNA and reduced transcription of TGF-β compared with healthy skin (P < 0.05). Higher levels of IFN-γ, TNF-α and IL-2 mRNA were seen in lesional compared with non-lesional and healthy skin (P < 0.05). There were no significant differences in IL-10, IL-6, IL-12p35 or IL-12p40 transcription between the three groups.

Conclusions This is the first report to demonstrate that canine atopic dermatitis is associated with over-production of IL-4. Clinical tolerance in healthy individuals appears to be associated with TGF-β, although it is unclear if this reflects an active mechanism or simply non-responsiveness of the immune system. Th1 cytokines may be induced by subsequent self-trauma and secondary infections in atopic skin. We believe that these results better characterize spontaneously occurring canine atopic dermatitis. We further propose that this should be investigated as a possible animal model of human atopic dermatitis.

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