Abstract: Li Ting, Zeng Qingwen, Chen Xiangming, Hu Yang, Zhang Haiqing, Yu Aihua, Wang Hairui Department of Dermatology, Nanxiang Hospital of Jiading District, Shanghai 201802, China（Li T, Chen XM, Hu Y, Zhang HQ, Yu AH, Wang HR）; Department of Pediatrics, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China （Zeng QW） Corresponding author: Hu Yang, Email: huyang0620@163.com 【Abstract】 Objective To evaluate effects of artesunate on rosacea-like inflammation in mouse models. Methods Twenty-five male BALB/c mice aged 7 weeks were injected subcutaneously with 40 μl antibacterial peptide LL-37 into the back once every 12 hours for 4 sessions to establish mouse models with rosacea-like inflammation. These 25 mice were randomly and equally divided into 5 groups: after each injection of LL-37, model group were gavaged with sodium chloride physiological solution, treatment groups gavaged with 25, 50 and 100 mg/kg artesunate solution separately, and positive control group gavaged with 30 mg/kg doxycycline hydrochloride solution. Another 5 healthy mice injected subcutaneously with pure water into the back for 4 sessions served as blank control group. Forty-eight hours after the initial injection of LL-37, changes in skin lesions and the intensity of erythema were assessed. Skin tissues at the dorsal injection site were resected and subjected to HE staining, the tissue structure was observed and the number of inflammatory cells was counted. Enzyme-linked immunosorbent assay （ELISA） was performed to estimate the activity of myeloperoxidase （MPO） in skin lesions. Results The model group showed obvious inflammatory reactions, and significantly increased erythema score（3.20 ± 0.84）, inflammatory cell count （517.27 ± 99.43） and MPO activity （0.57 ± 0.08） compared with the blank control group （all P < 0.01）. The positive control group showed significantly decreased erythema score （1.60 ± 0.89）, inflammatory cell count （270.93 ± 124.63） and MPO activity （0.40 ± 0.05） compared with the model group （P < 0.05, 0.01, 0.01, respectively）. Moreover, the erythema score, inflammatory cell counts and MPO activity were all significantly lower in 50- （1.80 ± 0.84, 286.00 ± 33.72, 0.43 ± 0.05, respectively） and 100-mg/kg artesunate groups （1.40 ± 0.55, 258.00 ± 36.44, 0.40 ± 0.06, respectively） than in the model group （P < 0.05 or 0.01）. However, there were no significant differences in the erythema score, inflammatory cell count and MPO activity between 50- or 100-mg/kg artesunate group and the positive control group（P > 0.05）. Conclusion Artesunate can inhibit rosacea-like inflammatory reactions in mouse models, especially the middle- and high-dose artesunate.