Kojima ENT Clinic, Kyoto, Japan.
Center of Anatomical, Pathological and Forensic Medical Researches, Graduate School of Medicine, Kyoto University, Japan.
Biochem Biophys Res Commun. 2024 Nov 5;732:150401. doi: 10.1016/j.bbrc.2024.150401. Epub 2024 Jul 14.
The pathophysiology of laryngopharyngeal reflux (LPR) and its impact on the vocal fold is not well understood, but may involve acid damage to vocal fold barrier functions. Two different components encompass vocal fold barrier function: the mucus barrier and tight junctions. Mucus retained on epithelial microprojections protects the inside of the vocal fold by neutralizing acidic damage. Tight junctions control permeability between cells. Here we developed an in vitro experimental system to evaluate acidic injury and repair of vocal fold barrier functions. We first established an in vitro model of rat vocal fold epithelium that could survive at least one week after barrier function maturation. The model enabled repeated evaluation of the course of vocal fold repair processes. Then, an injury experiment was conducted in which vocal fold cells were exposed to a 5-min treatment with acidic pepsin that injured tight junctions and cell surface microprojections. Both of them healed within one day of injury. Comparing vocal fold cells treated with acid alone with cells treated with acidic pepsin showed that acidic pepsin had a stronger effect on intercellular permeability than acid alone, whereas pepsin had little effect on microprojections. This result suggests that the proteolytic action of pepsin has a larger effect on protein-based tight junctions than on phospholipids in microprojections. This experimental system could contribute to a better understanding of vocal fold repair processes after chemical or physical injuries, as well as voice problems due to LPR pathogenesis.
喉咽反流（LPR）的病理生理学及其对声带的影响尚不清楚，但可能涉及酸对声带屏障功能的损害。声带屏障功能有两个不同的组成部分：黏液屏障和紧密连接。上皮微绒毛上保留的黏液通过中和酸性损伤来保护声带内部。紧密连接控制细胞之间的通透性。在这里，我们开发了一种体外实验系统来评估酸性对声带屏障功能的损伤和修复。我们首先建立了一种大鼠声带上皮的体外模型，该模型在屏障功能成熟后至少能存活一周。该模型能够重复评估声带修复过程的过程。然后，进行了损伤实验，其中将声带细胞暴露于酸性胃蛋白酶中 5 分钟，损伤紧密连接和细胞表面微绒毛。两者在损伤后一天内均愈合。与单独用酸处理的声带细胞相比，用酸性胃蛋白酶处理的声带细胞表明，胃蛋白酶对细胞间通透性的影响强于单独的酸，而胃蛋白酶对微绒毛几乎没有影响。这一结果表明，胃蛋白酶的蛋白水解作用对基于蛋白质的紧密连接的影响大于对微绒毛中磷脂的影响。该实验系统有助于更好地理解化学或物理损伤后声带的修复过程，以及由于 LPR 发病机制引起的嗓音问题。
