Gene transcription of pro-inflammatory cytokines and chemokines induced by IL-17A in canine keratinocytes.

BACKGROUND: Pro-inflammatory cytokines and chemokines produced by activated keratinocytes play an important role in the pathogenesis of canine atopic dermatitis (AD) as well as human AD. Recent studies suggest that keratinocytes activated by IL-17A are involved in the pathogenesis of human AD. However, the role of IL-17A in canine keratinocytes is poorly understood. HYPOTHESIS/OBJECTIVES: Interleukin-17A would induce the transcription of pro-inflammatory cytokines and chemokines in canine keratinocytes. METHODS: The transcription levels of pro-inflammatory cytokines and chemokines were quantified in a canine keratinocyte cell line stimulated with recombinant canine (rc) IL-17A. RESULTS: The transcription of GM-CSF, S100A8, IL-8 and IL-19 in cultured keratinocytes was significantly enhanced at 24 h after stimulation with rcIL-17A. CONCLUSIONS AND CLINICAL IMPORTANCE: Keratinocytes activated by IL-17A have the ability to produce various pro-inflammatory cytokines and chemokines, suggesting that IL-17A may play a central role of the development of Th2-associated inflammation in canine AD.

Involvement of nuclear factor of activated T cells in granulocyte-macrophage colony-stimulating factor production in canine keratinocytes stimulated with a cysteine protease.

BACKGROUND: A previous study demonstrated that the cysteine protease of Dermatophagoides farinae induced production of granulocyte-macrophage colony-stimulating factor (GM-CSF) in a canine epidermal keratinocyte progenitor cell line (CPEK); however, the molecular mechanism has not been elucidated. HYPOTHESIS/OBJECTIVES: Given that the transcription of GM-CSF mRNA in human lymphocytes is mainly regulated by the nuclear factor of activated T cells (NFAT), it is hypothesized that NFAT also contributes to GM-CSF production in canine keratinocytes stimulated with a cysteine protease. METHODS: Nuclear translocation of NFAT was evaluated in CPEK cells in the absence or presence of the cysteine protease papain. We also investigated whether blockade of NFAT could inhibit GM-CSF production. RESULTS: Papain-induced nuclear translocation of NFAT, producing GM-CSF, was partly inhibited by ciclosporin. CONCLUSIONS AND CLINICAL IMPORTANCE: The results suggest that GM-CSF production mediated by the cysteine protease is regulated not only by NFAT but also by unknown signalling pathways in canine keratinocytes.

Production of GM-CSF mediated by cysteine protease of Der f in canine keratinocytes.

House dust mite (HDM) allergens are the most common allergens for induction of IgE-mediated hypersensitivity. Recently, epicutaneous sensitization with HDM allergens has been emphasized in the development of atopic dermatitis (AD) by producing various soluble factors in keratinocytes. Among the soluble factors, GM-CSF is a key molecule that activates Langerhans cells, antigen-presenting cells in the epidermis. In the present study, we investigated the effects of Dermatophagoides farinae (Der f) on GM-CSF production in a canine keratinocyte cell line, CPEK. CPEKs were found to produce GM-CSF upon stimulation by Der f. The GM-CSF production was suppressed by addition of a cysteine protease inhibitor. The present results suggest that cysteine protease-derived Der f may be an initiator of allergic inflammation by inducing the production of GM-CSF in keratinocytes.