The Thai Journal of Veterinary Medicine


The pathological alterations in skin keratinocyte proliferation and differentiation in canine atopic dermatitis(CAD) were investigated in 20 small breed dogs with CAD (10 of which displayed lesional CAD skin and 10 nonlesionalCAD skin) and 11 healthy control animals. Biopsy of lesional CAD skin showed orthokeratotichyperkeratosis. Immunohistochemistry (IHC) of Ki-67, a cellular marker for proliferation, showed a higher epidermalcell proliferation rate in the CAD dogs (p< 0.05) which positively correlated with Canine Atopic Dermatitis Extent andSeverity Index, CADESI-03 (p< 0.01). IHC labeling indicated reduced expression of cornified envelope proteins,involucrin (IVL) and filaggrin (FLG) in both lesional and non-lesional skin (p< 0.05). In contrast, expression oflympho-epithelial Kazal-type inhibitor (LEKTI), which has been reported to inhibit proteases that cleave proFLG intoFLG, was increased in lesional skin compared to the normal controls (p< 0.05). The IHC results showed a positivecorrelation between CADESI-03 and LEKTI expression and a negative correlation between CADESI-03 and IVLexpression. In conclusion, the present study demonstrates that epidermal hyperkeratosis in CAD is related todisturbance of both epidermal proliferation and cornified envelope differentiation. This is the first report of acorrelation of LEKTI with CAD.

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