Abstract: Jia Kun*, Zhang Xiaofeng, Dong Yuhao, Zhang Yan, Ma Weiyuan. *Shandong University School of Medicine, Jinan 250012, China Corresponding author：Ma Weiyuan, Email: dermatologyqlh@163.com 【Abstract】 Objective To detect the expression of the transcription factor CCAAT/enhancer-binding protein alpha （C/EBP-α） in the epidermis of psoriasis vulgaris lesions, and to investigate its correlation with abnormal keratinocyte proliferation and disease severity. Methods Biopsy specimens were obtained from the lesions of 30 patients with psoriasis vulgaris and normal skin of 30 healthy human controls. A two-step immunohistochemical procedure was performed to detect the expressions of C/EBP-α and Ki-67 in these specimens, and Western blot to quantify the expression of C/EBP-α. The proliferation index of keratinocytes was calculated according to the expression intensity of Ki-67. Statistical analysis was carried out by using the SPSS 17.0 software, and Pearson correlation analysis was conducted to assess the relationship of C/EBP-α expression level with proliferation index of keratinocytes and psoriasis area and severity index （PASI） score. Results C/EBP-α was predominantly expressed in the cytoplasm of keratinocytes, while Ki-67 in the nuclei of keratinocytes. Compared with the normal skin, the psoriatic lesions showed a significantly lower expression of Ki-67 （t = 7.82, P < 0.05）, but higher proliferation index of keratinocytes （t = 4.54, P < 0.05）. The expression level of C/EBP-α was negatively correlated with the proliferation index of keratinocytes and PASI score in the patients （both P < 0.05）. Western blot also showed an obvious decrease in the expression of C/EBP-α in psoriatic lesions. Conclusions The expression of C/EBP-α is decreased in lesions of psoriasis vulgaris, which might be involved in the pathogenesis of psoriasis vulgaris.

Key words: Psoriasis, CCAAT-enhancer-binding protein-alpha, Proliferation inde