Moore Emily R, Konermann Anna
Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA.
Department of Orthodontics, University of Bonn, 53111 Bonn, Germany.
Int J Mol Sci. 2024 Nov 25;25(23):12648. doi: 10.3390/ijms252312648.
Periodontal ligament (PDL) cells are crucial for mechanosensation and mechanotransduction within the PDL, yet the role of primary cilia in orthodontic force transmission has not been examined. While bone morphogenetic protein (BMP) signaling significantly influences ciliary function, its effect on cellular responses to mechanical stress has not been investigated. This study aims to investigate whether primary cilia and BMP signaling are involved in the periodontal ligament's response to orthodontic tooth movement and the resultant mechanical strain. To visualize primary cilia, human PDL cells were cultured on glass-bottom dishes for five days, with a subset fixed daily, followed by immunostaining with anti-acetylated α-tubulin and Alexa Fluor 568 and imaging using a fluorescence microscope under 405 nm and 561 nm laser excitation. Human PDL cells were grown on Bioflex culture plates and subsequently exposed to static tensile strains of 2.5%, 5%, 10%, 20%, on a FX-6000T™ Tension System for 24 h. RT-qPCR was performed to evaluate changes in expression of primary cilia via expression, mechanotransduction via expression, and signaling-related genes. Histological specimens from orthodontically loaded and control human premolars were investigated for primary cilia and BMP signaling using immunohistochemistry and confocal microscopy. Primary cilia were observed in PDL cells from day one, with their incidence and length increasing over time alongside cell density. BMP signaling components, including upregulated genes such as (10.99-14.97 fold), (3.19-5.45 fold), and (1.64-8.40 fold), consistently responded to strain, while and showed differential regulation depending on strain intensity. In vivo, orthodontic movement activated BMP signaling and increased primary cilium incidence in the PDL. These findings indicate the potential role of primary cilia and BMP signaling in the mechanosensitivity of PDL cells under orthodontic forces. Further studies are required to understand the complex mechanotransduction mechanisms and role of these components in cellular adaptation during orthodontic tooth movement.
牙周韧带（PDL）细胞对于牙周韧带内的机械感觉和机械转导至关重要，但初级纤毛在正畸力传递中的作用尚未得到研究。虽然骨形态发生蛋白（BMP）信号显著影响纤毛功能，但其对细胞对机械应力反应的影响尚未被研究。本研究旨在探讨初级纤毛和BMP信号是否参与牙周韧带对正畸牙齿移动及由此产生的机械应变的反应。为了可视化初级纤毛，将人牙周韧带细胞在玻璃底培养皿中培养5天，每天固定一部分，然后用抗乙酰化α-微管蛋白和Alexa Fluor 568进行免疫染色，并在405nm和561nm激光激发下使用荧光显微镜成像。将人牙周韧带细胞接种在Bioflex培养板上，随后在FX-6000T™张力系统上暴露于2.5%、5%、10%、20%的静态拉伸应变24小时。进行RT-qPCR以评估初级纤毛相关基因的表达变化、机械转导相关基因的表达变化以及BMP信号相关基因的表达变化。使用免疫组织化学和共聚焦显微镜对正畸加载和对照人前磨牙的组织学标本进行初级纤毛和BMP信号的研究。从第1天起就在牙周韧带细胞中观察到初级纤毛，其发生率和长度随时间增加，同时细胞密度也增加。BMP信号成分，包括如（10.99 - 14.97倍）、（3.19 - 5.45倍）和（1.64 - 8.40倍）等上调基因，始终对应变有反应，而和则根据应变强度表现出差异调节。在体内，正畸移动激活了BMP信号并增加了牙周韧带中初级纤毛的发生率。这些发现表明初级纤毛和BMP信号在正畸力作用下牙周韧带细胞的机械敏感性中的潜在作用。需要进一步研究以了解这些成分在正畸牙齿移动过程中细胞适应的复杂机械转导机制和作用。
