Abstract:

Objective To detect the expression of proteinase activated receptor 2 （PAR-2） in the skin of patients with atopic dermatitis （AD） and to evaluate the effects of tacrolimus on the expression. Methods Six patients with acute moderate or severe AD were enrolled in this study and topically treated with tacrolimus 0.1% ointment twice daily for 3 weeks. Tissue samples were obtained from the lesions and non-lesional skin at least 10 cm away from the lesions before and after the 3-week treatment. Skin specimens from 6 normal human controls served as the control. Patients were evaluated at the baseline, 1 and 3 weeks after the beginning of treatment for clinical symptoms and signs by visual analogue scale （VAS）, eczema area and severity index （EASI） and investigator′s global assessment （IGA）. The expression of PAR-2 in tissue specimens were determined by immunohistochemistry. Results PAR-2 was expressed throughout the whole epidermis, especially in the granular layer, hair follicles, sweat glands, endothelial cells and nerve fiber-like structures. Before treatment, the expression level （mean optical density） of PAR-2 in keratinocytes was 4339.6 ± 115.8 in lesional skin of AD patients, significantly higher than that in non-lesional skin （4189.0 ± 228.9, t = 2.85, P < 0.05） and in normal skin （3864.0 ± 237.3, t = 4.31, P < 0.05）. After the 3-week treatment with tacrolimus ointment, the expression level of PAR-2 significant decreased to 3942.4 ± 176.6 in keratinocytes from lesional skin of patients with AD （t = 4.55, P < 0.05）. The expression level of PAR-2 was positively correlated with VAS score for itch, EASI and IGA score in the patients. Conclusions The expression of PAR-2 is enhanced in keratinocytes of lesions from AD patients, and is positively correlated with itch and lesion severity. Topical tacrolimus may suppress the overexpression of PAR-2 in keratinocytes in lesional skin of AD.

Key words: Keratinocyte