Abstract: Objective To study the regulatory effect of miR-155 on osteogenic differentiation of periodontal ligament stem cells (PDLSCs) in inflammatory microenvironment. Methods PDLSCs were cultured and divided into control group, tumor necrosis factor group-α(TNF-α) group, miR-negative control (NC) group, TNF-α+miR-NC group, TNF-α+miR-155 inhibitor group and miR-155 group according to different treatment methods. Fluorescence quantitative PCR was used to detect miR-155, recombinantrunt related transcription factor 2 (Runx2), osteocalcin (OCN), collagen Ⅰ (Col-Ⅰ),bone morphogenetic protein 5 (BMP5) and bone morphogenetic protein 10 (BMP10) expression levels; Western blot was used to detect Runx2, OCN, Col-Ⅰ, BMP5, BMP10 protein expression; alizarin red staining was used to detect the formation of calcium nodules in cells; the double luciferase reporter gene was used to verify that miR-155 targeted BMP5 and BMP10. Results Compared with the control group, the expression level of miR-155 in PDLSCs in the TNF-α group increased; the mRNA and protein expression levels of Runx2, OCN, Col-Ⅰ and the formation of calcium nodules decreased (P＜0.05). Compared with the miR-NC group, the mRNA and protein expression levels of Runx2, OCN and Col-Ⅰ and the formation of calcium nodules in PDLSCs in the TNF-α+miR-NC group were decreased (P＜0.05). Compared with the TNF-α+miR-NC group, the mRNA and protein expression levels of Runx2, OCN and Col-Ⅰ and the formation of calcium nodules in PDLSCs in the TNF-α+miR-155 inhibitor group increased (P＜0.05). miR-155 negatively regulated the expressions of BMP5 and BMP10. Conclusion The expression of miR-155 in PDLSCs increases in inflammatory microenvironment. Knocking down miR-155 promotes the osteogenic differentiation of PDLSCs in inflammatory microenvironment. Targeting BMP5 and BMP10 is the relevant molecular mechanism.

Key words: periodontitis, miR-155, periodontal ligament stem cell, osteogenic differentiation, bone morphogenetic protein 5, bone morphogenetic protein 10