Abstract: Objective To detect the expression of miR-203a-5p and MAPK1 in inflammation human periodontal ligament cells,and investigate the regulatory effects of miR-203a-5p and MAPK1 on periodontitis. Methods To isolated culture and identificated of hPDLSCs by Flow Cytometry. （HPDLSCs were divided into control group, LPS stimulation group, mir-203a-5p mimic transfection group and mir-203a-5p inhibitor transfection group）hPDLSCs were divided into the control group,LPS stimulation group, miR-203a-5p mimic transfected cells group and miR-203a-5p inhibitor transfection cells group, the effect of miR-203a-5p on MAPK1 gene was verified by RT-qPCR,Western blot and the dual-luciferase reporter assay. Results The expression of CD73 and CD90 was positive in hPDLSCs.The expression of miR-203a-5p was obviously increased in LPS stimulation group（P<0.05）. miR-203a-5p mimic and LPS could promote the expression of miR-203a-5p and suppress the expression of mRNA and protein of MAPK1（P<0.05）; miR-203a-5p inhibitor could down-expression of miR-203a-5p and the expression of mRNA and protein of MAPK1 was increased（P<0.05）; luciferase assay showed that miR-203a-5p and MAPK1 have targeted complementary relationship.Conclutions miR-203a-5p can regulate the inflammatory reac- tion process of periodontitis target by downregulating the expression of MAPK1 gene.

Key words: LPS, miR-203a-5p, hPDLSCs , MAPK1