Abstract: Hu Xiaoping, Zhang Wei, Chen Bancheng, Chen Shihong, Wang Yongqiang, Yu Bo. Department of Dermatology, Peking University Shenzhen Hospital, Guangdong 518036, China Corresponding author: Yu Bo, Email: yubomd@163.com 【Abstract】 Objective To measure the expression of peroxisome proliferator-activated receptor β/δ （PPARβ/δ） in epidermal keratinocytes from patients with psoriasis, and to investigate its regulatory factors. Methods Tissue specimens were obtained from both lesional and non-lesional skin of 20 patients with psoriasis as well as from normal skin of 15 human controls. An immunohistochemical method was used to examine the expression of PPARβ/δ in these tissue specimens. Epidermal keratinocytes were isolated from these tissue specimens and subjected to a primary culture. After several passages of subculture, non-lesional psoriatic keratinocytes were stimulated with different concentrations of GW501516 （an agonist of PPARβ/δ, 0 － 100 ng/ml） and Ca2+ （0 － 3.0 mmol/L）. Reverse transcription-PCR and Western blot were performed to measure the mRNA and protein expressions of PPARβ/δ in the primary keratinocytes and stimulated keratinocytes respectively. Results Immunohistochemistry showed that the expression intensity of PPARβ/δ was significantly higher in lesional psoriatic skin than in normal control skin（t = 19.28, P < 0.01） and non-lesional psoriatic skin（t = 23.26, P < 0.01）. Increased mRNA and protein levels of PPARβ/δ were observed in lesional psoriatic keratinocytes as compared to normal control keratinocytes （both P < 0.01） and non-lesional psoriatic keratinocytes（both P < 0.01）. Among these stimulated non-lesional psoriatic keratinocytes, those treated with GW501516 at 10 ng/ml and those with Ca2+ of 1.0 mmol/L showed the strongest expression of PPARβ/δ （both P < 0.01）. Conclusions The expression of PPARβ/δ, which is higher in lesional psoriatic skin, can be enhanced by GW501516 and Ca2+ in keratinocytes.

Key words: Psoriasis, Keratinocytes, PPARβ/δ