Regulation of Inflammatory Responses in the Cochlea

描述(申请人提供)：炎症是一种有益的宿主对外来挑战或组织损伤的反应，最终导致组织结构和功能的恢复。白细胞迁移到损伤或感染部位是炎症反应的决定性步骤。然而，在哺乳动物的耳蜗里，必须防止白细胞迁移到听觉器官，因为它可能通过破坏Corti腔边界器官(解剖学上定义为网状板)处的紧密连接屏障而取消耳蜗内的潜力，导致感觉运动性外毛细胞的凋亡和不可逆转的深度耳聋。因此，在Corti器官中永远不会发现白细胞，除非发生严重的、不可逆转的耳蜗损伤。耳蜗用来防止白细胞迁移的机制仍不清楚。目前保护Corti器官免受炎症损害的黄金标准临床策略是局部应用糖皮质激素。然而，糖皮质激素提供这种保护的机制也是未知的。这项提议的目标是填补我们知识中的这些空白，这是我们寻求了解哺乳动物耳蜗炎性反应调节的关键一步。我们的初步研究支持以下假设：1)Annexin A1(ANXA1)是先天性和获得性免疫系统许多方面的关键调节因子，在防止白细胞迁移到OC和促进炎症反应的消退方面发挥重要作用；2)糖皮质激素通过肌球蛋白IIC驱动的机制刺激豚鼠Hensen细胞释放ANXA1；以及3)Hensen细胞将ANXA1储存在填充其细胞质的显著脂滴中。因此，我们建议使用豚鼠作为体内模型，听觉细胞系作为体外模型，并结合非重叠技术和方法学方法来验证这些假设，以解决以下具体目标：1)证明由亨森细胞释放的ANXA1阻止白细胞迁移，2)阐明ANXA1参与细胞内转运和释放的机制/S，以及3)确定和表征S参与汉森细胞脂滴储存和释放ANXA1的机制。

DESCRIPTION (provided by applicant): Inflammation is a beneficial host response to foreign challenges or tissue injury that leads ultimately to the restoration of tissue structure and function. Leukocyte migration to sites of injury or infection is a defining step of inflammatory responses. In the mammalian cochlea, however, leukocyte migration into the auditory organ must be prevented as it may abolish the endocochlear potential by disrupting the tight-junction barrier at the organ of Corti luminal border (anatomically defined as the reticular lamina), leading to apoptosis of sensorimotor outer hair cells and irreversible, profound deafness. Thus, leukocytes are never found in the organ of Corti except in cases of extreme, irreversible cochlear damage. The mechanism used by the cochlea to prevent leukocyte migration is still unknown. The current gold standard clinical strategy to protect the organ of Corti against inflammatory damage is the local delivery of glucocorticoids. However, the mechanism by which glucocorticoids confer this protection is also unknown. The goal of this proposal is to fill these gaps in our knowledge, a crucial step in our quest to understand the regulation of inflammatory responses in the mammalian cochlea. Our preliminary studies provide strong support to the following hypotheses: 1) Annexin A1 (ANXA1), a pivotal regulator of many aspects of the innate and adaptive immune systems, have a major role in preventing leukocyte migration into the OC and facilitating the resolution phase of the inflammatory response; 2) glucocorticoids stimulate guinea pig Hensen cells to release ANXA1 via a myosin IIC-driven mechanism; and 3) Hensen cells store ANXA1 inside the prominent lipid droplets filling their cytoplasm. Thus, we propose to use the guinea pig as an in vivo model, an auditory cell line as an in vitro model, and a combination of non-overlapping techniques and methodological approaches to test these hypotheses by addressing the following Specific Aims: 1) Demonstrate that ANXA1 released by Hensen cells prevents leukocyte migration, 2) Elucidate the mechanism/s involved in the intracellular transport and release of ANXA1, and 3) Identify and characterize the mechanism/s involved in the storage and release of ANXA1 by Hensen cell lipid droplets.