N-acetyl Cysteine Inhibits Cell Proliferation and Differentiation of LPSInduced MC3T3-E1 Cells Via Regulating Inflammatory Cytokines

Background: Peri-implantitis is one of the most common complications in oral implantation and could lead to the loss of the function of bone tissues around implants. Methods: This study used lipopolysaccharide (LPS) as a stimulant for MC3T3-E1 cells and N-acetyl cysteine (NAC) as an inhibitor to inhibit the effect of LPS to investigate the effect of NAC on the expression of bone formation related factors and inflammatory-related factors of osteoblasts under the action of LPS. Results: In this study, we found that the cell proliferation and cell differentiation were significantly promoted when NAC concentrations were between 0 ~ 0.5 mM, but were inhibited when the concentration exceeded 0.5 mM. LPS had a slightly promoting effect on the cell proliferation before 20 μg/mL but inhibited the cell proliferation after 20 μg/mL. LPS reduced protein and gene expressions of Runx2, ALP and BGP and increased protein and gene expressions of NF-ΚB and TNF-α. NAC reversibly regulated the LPS’s regulation on the expression of MC3T3-E1 cell cytokine gene and protein. Conclusion: The optimal NAC concentration for treating MC3T3-E1 cells is 0.5 mM, and the optimal LPS concentration for stimulating MC3T3-E1 cells is 20 μg/mL. NAC plays an active role in regulating the differentiation of MC3T3-E1 cells, and can inhibit LPS to regulate the differentiation of MC3T3-E1 cells. NAC promotes the expression of an osteogenic factor of MC3T3-E1cells and inhibits the expression of inflammatory cytokines.