Expression of peroxisome proliferator-activated receptor β/δ in psoriatic epidermal keratinocytes

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