Abstract: Objective To explore the effect of P38 mitogen-activated protein kinase (MAPK)on osteogenic differentiation and Wnt / Ca2 + signaling pathways in periodontal ligament stem cells(PDLSC) under microinflammatory environment. Methods Human PDLSC were divided into 4groups: control group, TNF-α group, TNF-α + SB203580 group ( 20 μmol / L SB20358 ) and TNF-α + SB203580 + XAV939 group (20 μmol / L SB20358 + 10 μmol / L XAV939). Except for cells in the control group, cells in the other groups were given 10 ng / mL TNF-α to simulate inflammatory microenvironment. The osteogenic differentiation ability was detected by alizarin red staining. The activity of alkaline phosphatase (ALP) in each group was compared. The expression levels of RUNt-related transcription factor 2 (Runx2), osteocalcin (OCN), Osterix (OSX) and osteopontin (OPN) were detected by qRT-PCR, and the expression levels of P38 MAPK, β-catenin, calmodulin dependent protein kinase Ⅱ (CaMKⅡ ) and Nemo-like (NLK) were detected byWestern blotting. Results The staining intensity and number of calcification nodules in the TNF-αgroup were significantly decreased, and in comparison of those in the TNF-α group, the staining intensity and number of calcification nodules were significantly improved in the TNF-α + SB203580 group, but there was no significant difference in staining intensity or number of calcification nodules between the TNF-α + SB203580 + XAV939 group and the TNF-α + SB203580 group. Compared with those in the control group, the activity of ALP and mRNA expression levels of Runx2, OCN, OSXand OPN were decreased in the TNF-α group (P< 0. 05), the expression level of P38 MAPK protein was increased (P< 0. 05), and the expression levels of β-catenin, CaMKⅡ and NLK proteins were decreased (P< 0. 05). Compared with those in the TNF-α group, the activity of ALP and mRNA expression levels of Runx2, OCN, OSX and OPN were increased in the TNF-α + SB203580group (P< 0. 05), the expression level of P38 MAPK protein was decreased (P< 0. 05), and the expression levels of β-catenin, CaMKⅡ and NLK proteins were increased (P < 0. 05). Comparedwith those in the TNF-α + SB203580 group, the expression level of β-catenin protein was decreasedin the TNF-α + SB203580 + XAV939 group (P< 0. 05), but there was no significant difference inALP activity, mRNA expression levels of Runx2, OCN, OSX and OPN or expression levels of P38MAPK, CaMKⅡ and NLK proteins between the two groups (P> 0. 05). Conclusion P38 MAPKinhibitor can improve osteogenic differentiation of PDLSC under inflammatory microenvironment, which may be related to activating Wnt / Ca2 + signaling pathways.

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