First report in a dog model of atopic dermatitis: expression patterns of protease-activated receptor-2 and thymic stromal lymphopoietin.

Abstract

Protease-activated receptor (PAR)-2 plays a crucial role in inflammation and the skin barrier. Protease-activated receptor-2 is activated by proteolytic enzymes of allergens and stimulates thymic stromal lymphopoietin (TSLP), promoting T-helper2 cytokines. In humans with atopic dermatitis (AD), increased expression of PAR-2 and TSLP has been reported. To compare the pattern of staining of PAR-2 and TSLP between normal and atopic beagle dogs. The hypothesis tested was that increased expression is present in atopic dog skin compared with healthy control skin. Eight atopic and five normal dogs were challenged for 3days with house dust mites. Skin biopsies were taken to measure the intensity, distribution, integrity and cell staining pattern on days 0, 3 and 10, both objectively and subjectively. Clinical signs were scored and compared between groups. Atopic dogs showed a significant increase in clinical scores on days3 (peak of challenge) and 10 (resolution) and a significant condensed staining pattern for TSLP in the stratum basale at all times in comparison to normal dogs. They showed a significant patchy pattern for PAR-2 on days 0 and 3 and for TSLP at all times compared with normal dogs. The intensity itself was not significantly increased in atopic dogs compared with normal animals for both PAR-2 and TSLP. These preliminary findings do not confirm a difference in the amount of expression but rather in its pattern. Studies using PAR-2 or TSLP inhibitors could shed light on their clinical relevance.