Abstract: PANG Qin, ZOU Xi, HE Li*. *Department of Dermatology, First Affiliated Hospital of Kunming Medical University, Yunnan Research Center for Dermatology and Venereology, Kunming 650032, China Corresponding author: HE Li, Email: heli2662@yahoo.com.cm 【Abstract】 Objective To explore the anti-inflammatory mechanisms of purslane by evaluating its effects on the expression of tumor necrosis factor-α （TNF-α） and intercellular adhesion molecule 1 （ICAM-1）. Methods A model of inflammation was developed in 45 mice by painting xylene to the auricle of the right ears, which were then divided into 3 groups to receive no treatment （negative control group）, be topically treated with the extraction of purslane from South Korea （positive control group） or Yunnan province （experimental group）. Fifteen mice receiving no sensitization nor treatment served as the blank control group. Two hours after the single topical treatment, skin tissue samples were obtained from the site of experimental inflammation and subjected to pathological examination by using hematoxylin and eosin （HE） staining. Immunohistochemistry was performed to quantify the expression of TNF-α and ICAM-1 in the tissue samples. Results Pathological examination showed blood vessels and a small quantity of lymphocytes in murine dermis of the blank control group as well as loose and edematous dermis infiltrated with massive lymphocytes in the negative control group. However, there was only mild edema and perivascular infiltration with some inflammatory cells in the dermis of the positive control group and experimental group. Neither TNF-α nor ICAM-1 was expressed in the skin tissue of the blank control group, but an intense expression was observed for TNF-α in the vascular endothelial cell membrane and for ICAM-1 in the vascular endothelial cell membrane and lymphocyte membrane in the negative control group, which was significantly downregulated by the purslane from South Korea in the positive control group and by the purslane from Yunnan province in the experimental group （all P < 0.01） . Rank sum test showed a statistical difference in the expression level of TNF-α and ICAM-1 between the blank control group and experimental group （both P < 0.01）. Conclusion The purslane from Yunnan province may counteract inflammation by affecting the expression of TNF-α and ICAM-1.