The temporomandibular joint disc is a fibrocartilaginous structure, composed of collagen fibers, elastin fibers, and proteoglycans. Despite the crucial role of elastin fibers in load‐bearing properties of connective tissues, its contribution in temporomandibular joint disc biomechanics has been disregarded. This study attempts to characterize the structural–functional contribution of elastin in the temporomandibular joint disc. Using elastase, we selectively perturbed the elastin fiber network in porcine temporomandibular joint discs and investigated the structural, compositional, and mechanical regional changes through: (a) analysis of collagen and elastin fibers by immunolabeling and transmission electron microscopy; (b) quantitative analysis of collagen tortuosity, cell shape, and disc volume; (c) biochemical quantification of collagen, glycosaminoglycan and elastin content; and (d) cyclic compression test. Following elastase treatment, microscopic examination revealed fragmentation of elastin fibers across the temporomandibular joint disc, with a more pronounced effect in the intermediate regions. Also, biochemical analyses of the intermediate regions showed significant depletion of elastin (50%), and substantial decrease in collagen (20%) and glycosaminoglycan (49%) content, likely due to non‐specific activity of elastase. Degradation of elastin fibers affected the homeostatic configuration of the disc, reflected in its significant volume enlargement accompanied by remarkable reduction of collagen tortuosity and cell elongation. Mechanically, elastase treatment nearly doubled the maximal energy dissipation across the intermediate regions while the instantaneous modulus was not significantly affected. We conclude that elastin fibers contribute to the restoration and maintenance of the disc resting shape and actively interact with collagen fibers to provide mechanical resilience to the temporomandibular joint disc.

中文翻译：

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弹性蛋白酶消化后颞下颌关节盘结构和机械特性的改变。

颞下颌关节盘是一种纤维软骨结构，由胶原纤维、弹性蛋白纤维和蛋白聚糖组成。尽管弹性蛋白纤维在结缔组织的承载特性中起着至关重要的作用，但它在颞下颌关节盘生物力学中的贡献却被忽视了。本研究试图表征弹性蛋白在颞下颌关节盘中的结构功能贡献。使用弹性蛋白酶，我们选择性地扰乱了猪颞下颌关节盘中的弹性蛋白纤维网络，并通过以下方式研究了结构、组成和机械区域的变化：（a）通过免疫标记和透射电子显微镜分析胶原蛋白和弹性蛋白纤维；(b) 胶原曲折度、细胞形状和椎间盘体积的定量分析；(c) 胶原的生化定量，糖胺聚糖和弹性蛋白含量；(d) 循环压缩试验。弹性蛋白酶治疗后，显微镜检查显示颞下颌关节盘的弹性蛋白纤维碎裂，中间区域的影响更为明显。此外，中间区域的生化分析显示弹性蛋白显着消耗 (50%)，胶原蛋白 (20%) 和糖胺聚糖 (49%) 含量显着减少，这可能是由于弹性蛋白酶的非特异性活性。弹性蛋白纤维的降解影响椎间盘的稳态配置，反映在其显着的体积增大伴随着胶原扭曲和细胞伸长的显着减少。机械地，弹性蛋白酶处理使中间区域的最大能量耗散几乎翻了一番，而瞬时模量没有受到显着影响。我们得出结论，弹性蛋白纤维有助于椎间盘静止形状的恢复和维持，并与胶原纤维积极相互作用，为颞下颌关节盘提供机械弹性。