A comparative study of epidermal tight junction proteins in a dog model of atopic dermatitis

Abstract

BACKGROUND: Tight junctions (TJ) are important for skin barrier function and could be relevant in modulating allergen penetration in atopic dermatitis (AD). Humans with AD have been described to have decreased expressions of some TJ proteins in the skin. HYPOTHESIS/OBJECTIVES: This study aimed to investigate TJ protein expression using an experimental AD model in dogs. METHODS: Skin biopsies from six atopic (nonlesional skin) and five normal beagle dogs were stained for TJ proteins [zonula occludens 1 (ZO-1), occludin, claudin-1] by immunohistochemistry. Staining intensity was evaluated both objectively using imaging software and subjectively. Six images/sections were randomized and blindly scored by six investigators for intensity, distribution, integrity and staining pattern. RESULTS: The intensity of ZO-1 was significantly decreased in the atopic group objectively (P = 0.010) and subjectively (P = 0.002) relative to the normal group. Occludin was decreased significantly subjectively (P = 0.027) but not objectively. Claudin was not significantly different between groups by either quantification. Additionally, only ZO-1 demonstrated a significantly patchier staining pattern in the atopic group. There was no consistent staining pattern in this study. CONCLUSIONS AND CLINICAL IMPORTANCE: ZO-1 and occludin, which have not been described to be associated with the development of AD in humans, could play a role in this atopic dog model. Further investigation on the expression and modulation of TJ proteins and their clinical relevance is needed.