Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing, China.
Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China.
J Periodontol. 2021 Nov;92(11):128-138. doi: 10.1002/JPER.20-0806. Epub 2021 Aug 6.
Migration of cementoblasts to resorption lacunae is the foundation for repairing root resorption during orthodontic tooth movement. Previous studies reported that autophagy was activated by compression in periodontal ligament cells. The aim of this study was to investigate the migration of cementoblasts and determine whether autophagy is involved in the regulation of cementoblast migration under compressive force.
Flow cytometry was employed to examine the apoptosis of murine cementoblasts (OCCM-30) at different compression times (0, 6, 12, and 24 hours) and magnitudes (0, 1.0, 1.5, and 2.0 g/cm ). Cell proliferation was examined using the CCK-8 method. Wound healing migration assays and transwell migration assays were performed to compare the migration of cementoblasts. Chloroquine (CQ) and rapamycin were used to inhibit and activate autophagy, respectively. The level of autophagy was determined using western blotting and immunofluorescence staining. The expression of matrix metalloproteinases (MMPs) was assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot analysis, and enzyme-linked immunosorbent assay (ELISA).
Cell apoptosis and proliferation did not significantly change in OCCM-30 cells under mechanical compression at magnitude of 1.5 g/cm for 12 hours. However, the migration of cementoblasts was significantly inhibited after the application of compressive force. MMP2, MMP9, and MMP13 mRNA expression was decreased, and MMP9 and MMP13 protein expression and secretion level were also decreased. Further, autophagic activity was inhibited in cementoblasts under compressive force. Treatment with chloroquine reduced the cellular migration, and rapamycin partially relieved the inhibition of cementoblast migration induced by the compressive force. MMP9 and MMP13 mRNA expression, protein expression, and secretion levels showed a similar trend.
Migration of OCCM-30 cells was inhibited under compressive force partially dependent on the inhibition of MMPs, which was mediated by downregulation of autophagy. The findings provide new insights into the role of autophagy in biological behaviors of cementoblasts under compressive force and a potential therapeutic strategy for reducing external root resorption.
成牙骨质细胞向吸收陷窝迁移是正畸牙齿移动过程中修复牙根吸收的基础。先前的研究报道，在牙周韧带细胞中，自噬被压缩激活。本研究旨在探讨成牙骨质细胞的迁移，确定自噬是否参与调节在压缩力下成牙骨质细胞的迁移。
采用流式细胞术检测不同压缩时间（0、6、12 和 24 小时）和压缩量（0、1.0、1.5 和 2.0 g/cm ）下鼠源性成牙骨质细胞（OCCM-30）的凋亡情况。采用 CCK-8 法检测细胞增殖。采用划痕愈合迁移实验和 Transwell 迁移实验比较成牙骨质细胞的迁移。分别用氯喹（CQ）和雷帕霉素抑制和激活自噬。采用 Western blot 和免疫荧光染色检测自噬水平。采用定量逆转录聚合酶链反应（qRT-PCR）、Western blot 分析和酶联免疫吸附试验（ELISA）检测基质金属蛋白酶（MMPs）的表达。
在 1.5 g/cm 压缩量下作用 12 小时，OCCM-30 细胞的细胞凋亡和增殖无明显变化。然而，成牙骨质细胞的迁移在施加压缩力后明显受到抑制。MMP2、MMP9 和 MMP13 的 mRNA 表达降低，MMP9 和 MMP13 的蛋白表达和分泌水平也降低。此外，成牙骨质细胞在压缩力下的自噬活性受到抑制。用氯喹处理可减少细胞迁移，雷帕霉素部分缓解了压缩力诱导的成牙骨质细胞迁移的抑制作用。MMP9 和 MMP13 的 mRNA 表达、蛋白表达和分泌水平呈现出相似的趋势。
成牙骨质细胞在压缩力下的迁移部分依赖于 MMPs 的抑制，这是通过下调自噬来介导的。这些发现为自噬在成牙骨质细胞在压缩力下的生物学行为中的作用提供了新的见解，并为减少外部牙根吸收提供了一种潜在的治疗策略。
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