Abstract: Zhu Chaoying, Wen Ju, Li Ting, Zhao Qinan, Qin Si, Ma Jing, Zheng Rongchang, Feng Jieying Department of Dermatology, Guangdong No.2 Provincial People′s Hospital, Affiliated to Southern Medical University, Guangzhou 510317, China Corresponding author: Wen Ju, Email: wenju3139@163.com 【Abstract】 Objective To evaluate effects of interleukin?36α （IL?36α） on psoriasiform skin lesions and C?C motif chemokine ligand 20 （CCL20） in mice. Methods Totally, 30 BALB/c female mice were randomly and equally divided into 3 groups: control group treated with topical vaseline cream on the shaved back and intracutaneous injection with phosphate buffer saline （PBS）, model group treated with topical imiquimod cream on the shaved back and intracutaneous injection with PBS, experimental group treated with topical imiquimod cream on the shaved back and intracutaneous injection with IL?36α solution. Psoriasis area severity index （PASI） was used to evaluate changes of psoriasiform skin lesions in mice, and light microscopy to observe morphological changes of skin lesions and to measure the thickness of the epidermis. Real?time fluorescence?based quantitative PCR （qRT?PCR） and Western blot analysis were performed to determine the of IL?36α in skin lesions in the control group and model group, and qRT?PCR, Western blot analysis and immunohistochemical study to evaluate changes of CCL20 levels in skin lesions. Results The model group showed significantly increased mRNA （?Ct value: 0.0195 ± 0.0059） and protein （3.922 ± 0.248） of IL?36α compared with the control group （mRNA: 0.0012 ± 0.0004, P < 0.05; protein: 0.690 ± 0.025, P < 0.05）. The mRNA and protein of CCL20 were significantly higher in the experimental group than those in the model group （mRNA: 2.152 ± 0.793 vs. 0.999 ± 0.178; protein: 0.397 ± 0.033 vs. 0.145 ± 0.030; both P < 0.05）, and higher in the model group than those in the control group （mRNA: 0.378 ± 0.075; protein: 0.025 ± 0.009; both P < 0.05）. Immunohistochemical study showed that the intensity of CCL20 in skin lesions significantly increased in the experimental group compared with that in the model group （Z = 2.294, P < 0.05）. Conclusion IL?36α may aggravate psoriasiform skin inflammation in mice by promoting CCL20 .