Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, Chile.
Center for Exercise, Metabolism and Cancer Studies CEMC2016, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
Front Endocrinol (Lausanne). 2021 Mar 1;11:606947. doi: 10.3389/fendo.2020.606947. eCollection 2020.
The masticatory system is a complex and highly organized group of structures, including craniofacial bones (maxillae and mandible), muscles, teeth, joints, and neurovascular elements. While the musculoskeletal structures of the head and neck are known to have a different embryonic origin, morphology, biomechanical demands, and biochemical characteristics than the trunk and limbs, their particular molecular basis and cell biology have been much less explored. In the last decade, the concept of muscle-bone crosstalk has emerged, comprising both the loads generated during muscle contraction and a biochemical component through soluble molecules. Bone cells embedded in the mineralized tissue respond to the biomechanical input by releasing molecular factors that impact the homeostasis of the attaching skeletal muscle. In the same way, muscle-derived factors act as soluble signals that modulate the remodeling process of the underlying bones. This concept of muscle-bone crosstalk at a molecular level is particularly interesting in the mandible, due to its tight anatomical relationship with one of the biggest and strongest masticatory muscles, the masseter. However, despite the close physical and physiological interaction of both tissues for proper functioning, this topic has been poorly addressed. Here we present one of the most detailed reviews of the literature to date regarding the biomechanical and biochemical interaction between muscles and bones of the masticatory system, both during development and in physiological or pathological remodeling processes. Evidence related to how masticatory function shapes the craniofacial bones is discussed, and a proposal presented that the masticatory muscles and craniofacial bones serve as secretory tissues. We furthermore discuss our current findings of myokines-release from masseter muscle in physiological conditions, during functional adaptation or pathology, and their putative role as bone-modulators in the craniofacial system. Finally, we address the physiological implications of the crosstalk between muscles and bones in the masticatory system, analyzing pathologies or clinical procedures in which the alteration of one of them affects the homeostasis of the other. Unveiling the mechanisms of muscle-bone crosstalk in the masticatory system opens broad possibilities for understanding and treating temporomandibular disorders, which severely impair the quality of life, with a high cost for diagnosis and management.
咀嚼系统是一组复杂而高度组织化的结构，包括颅面骨（上颌骨和下颌骨）、肌肉、牙齿、关节和神经血管元素。虽然头颈部的肌肉骨骼结构已知具有与躯干和四肢不同的胚胎起源、形态、生物力学需求和生化特征，但它们特定的分子基础和细胞生物学研究得较少。在过去的十年中，出现了肌肉-骨骼串扰的概念，包括肌肉收缩时产生的负荷和通过可溶性分子组成的生化成分。嵌入在矿化组织中的骨细胞通过释放影响附着骨骼肌内稳态的分子因子来响应生物力学输入。同样，肌肉来源的因子作为可溶性信号作用，调节下面骨骼的重塑过程。在分子水平上，这种肌肉-骨骼串扰的概念在下颌骨中尤为有趣，因为它与最大和最强的咀嚼肌之一——咬肌紧密的解剖关系。然而，尽管这两种组织在适当的功能方面存在紧密的物理和生理相互作用，但这个话题却很少被涉及。在这里，我们对文献进行了迄今为止最详细的综述之一，涉及咀嚼系统中肌肉和骨骼之间的生物力学和生化相互作用，包括在发育过程中和生理或病理重塑过程中。还讨论了咀嚼功能如何塑造颅面骨的证据，并提出了一个建议，即咀嚼肌和颅面骨作为分泌组织。我们进一步讨论了我们目前在生理条件下、功能适应或病理过程中从咬肌释放肌因子的发现，以及它们作为颅面系统中骨调节剂的潜在作用。最后，我们讨论了咀嚼系统中肌肉和骨骼之间串扰的生理意义，分析了其中一种改变会影响另一种的内稳态的病理学或临床程序。揭示咀嚼系统中肌肉-骨骼串扰的机制为理解和治疗严重影响生活质量、诊断和管理成本高的颞下颌关节紊乱症提供了广泛的可能性。
