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Canine epitheliotropic cutaneous lymphoma (cECL) is characterized by infiltration of neoplastic lymphocytes in the skin with a specific tropism for the epidermis. Migration of lymphocytes is strictly controlled by interactions between chemokines and chemokine receptors, which may be involved in the pathogenesis of cECL. In this study, we investigated mRNA transcription levels of several chemokines (CCL17, CCL19, CCL21, CCL22, CCL27, CCL28 and CXCL10) and chemokine receptors (CCR4, CCR7, CCR10 and CXCR3) in lesional skin of cECL by quantitative real-time RT-PCR. To examine the subsets of accumulating neoplastic lymphocytes, we also investigated transcription levels of type-1 (IFN-γ, IL-12p35, IL-12p40 and LT-α) and type-2 (IL-4 and IL-13) cytokines and cytotoxic markers (perforin and granzyme B). We found that the lesional skin had higher mRNA transcription of CCL19, CXCL10, CCR4, CCR7, CCR10 and CXCR3 and lower transcription of CCL27 than healthy dog skin (p<0.05). In addition, transcription levels of type-1 cytokine and cytotoxic markers in lesional skin were significantly higher than those in healthy dog skin. These results indicate that the transcription of some chemokines and chemokine receptors, which are necessary for skin-homing, epitheliotropism and peripheral segregation of T-cells, is upregulated in the lesional skin of cECL. In addition, our results also indicate that the subset of neoplastic lymphocytes in cECL is most likely type-1 cytotoxic T-cells., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A CC chemokine, CCL17/TARC, has been shown to be a factor in the immunopathogenesis of canine atopic dermatitis (cAD). In canine keratinocytes, the transcription of CCL17 mRNA is preferentially induced by tumor necrosis factor-alpha (TNF-α); however, its regulatory mechanism has not been elucidated. The aim of the present study is to clarify the regulatory mechanism of TNF-α-induced CCL17 mRNA transcription in canine keratinocytes leading to the development of a chemokine-targeted therapy for cAD. In a cell line of canine epidermal keratinocyte, CPEK, stimulation with TNF-α induced not only the activation of nuclear factor-kappa B (NF-κB) but also the phosphorylation of c-Jun-N-terminal kinase (JNK) and mitogen-activated protein kinase p38 (p38). Extracellular signal-regulated kinase (ERK) was found to be constitutively phosphorylated, which was temporarily augmented by TNF-α. Results of the inhibition assay indicated that the CCL17 mRNA transcription level was significantly decreased by p38 inhibitors but was not altered by either JNK or NF-κB inhibitors. Surprisingly, the ERK inhibitor increased the transcription level of CCL17 mRNA. Stimulation with epidermal growth factor (EGF), an ERK activator, suppressed the transcription of CCL17 mRNA. The present results suggest that TNF-α-induced CCL17 mRNA transcription in CPEK is positively regulated by p38 but negatively controlled by ERK., (Copyright © 2010 Elsevier B.V. All rights reserved.)

House dust mite (HDM) allergens are the most common allergens involved in the induction of IgE-mediated hypersensitivity. Recently, epicutaneous sensitization with HDM allergens has been emphasized in the development of atopic dermatitis (AD); however, direct stimulation of canine keratinocytes by mite allergens has not been well investigated. In the present study, we investigated the effects of Der f 1, a major allergen of Dermatophagoides farinae, on cytokine and chemokine gene expression in a canine keratinocyte cell line, CPEK. CPEK constitutively expressed mRNA for TNF-alpha, IL-12p35, IL-18, GM-CSF, TGF-beta, IL-8/CXCL8, TARC/CCL17, CTACK/CCL27 and MEC/CCL28. Of all the cytokines and chemokines investigated in CPEK, transcription levels of GM-CSF, IL-8/CXCL8 and TNF-alpha mRNA were significantly enhanced by stimulation with Der f 1. The present results suggest that Der f 1 can directly augment inflammatory cytokine and chemokine production from keratinocytes, and may initiate allergic inflammation independently of Type-I hypersensitivity.