Basic Mechanisms in Hearing Loss of Cochlear Origin

目的：感音神经性听力损失（SNHL）与军事的许多方面密切相关 包括爆炸伤。这项建议的总体目标是改善预防工作， 和退伍军人中SNHL的治疗。 研究设计：在前期的资助下，采用中等通量筛选毛发 细胞（HC）从哺乳动物耳蜗，我们确定了一些新的抗氧化剂和细胞 能够保护耳蜗毛细胞免受高剂量耳毒性损伤的信号传导抑制剂。 这些保护剂中的一些提供了比先前描述的几种OTO更好的保护。 保护剂。我们现在建议在体内评价这些化合物中最有效的，使用 一个单一的，不变的模型，噪声引起的听力损失的动物，使干预措施可以 严格比较。我们还将评估已知的HC保护剂，以提供基准。这将允许 我们确定最佳的化合物，以进一步发展为人类的药理干预。 方法学：将使用耳蜗噪声损伤的体内研究进行研究， 暴露后立即开始HC保护剂的脑内递送。我们会用一口井- 建立小鼠噪声损伤模型，用渗透压法向耳蜗外淋巴液递送化合物， 微型泵、系列听性脑干反应（ABR）和畸变产物耳声发射 （DPOAE）测听，以及耳蜗毛细胞和传入神经末梢的形态学评价。 过去一段时间的资助进展：在过去的资助期间，我们开发了一个 使用哺乳动物细胞筛选潜在耳保护剂文库的中通量方法 Corti器官，唯一含有损伤敏感的哺乳动物外部HC的组织。我们确定 几种抗氧化剂和几种细胞信号通路抑制剂，它们非常有效， 以前没有评估过HC保护。利用Corti器电穿孔模型， 转染后，我们还筛选了200多种转录因子，以增强HC 在非感觉细胞中ATOH 1表达引起的再生，发现了几个新的因子 拥有这种能力我们发现用espin 1进行基因治疗可以显著增强静纤毛， 再生HC的形成。最后，我们发现了一种新的保护性HC途径， ATP受体，在高刺激水平下降低HC的活性，保护它们免受噪音的影响 损害迄今为止，这些研究产生了20篇同行评审的出版物。 临床关系：SNHL的预防和治疗对退伍军人非常重要 和退伍军人事务部SNHL对退伍军人生活质量的影响是巨大的。SNHL和耳鸣也 在VA中占比任何其他疾病的残疾赔偿金和康复费用 很高。拟议的研究旨在开发新的和改进的治疗方法， 预防和治疗这一严重的健康问题。

Objectives: Sensorineural hearing loss (SNHL) is strongly associated with many aspects of military service including blast injury. The overall objectives of this proposal are to improve the prevention and treatment of SNHL in veterans. Research Design: During the previous period of funding, using medium-throughput screening of hair cells (HCs) from the mammalian cochlea, we identified a number of novel antioxidants and cell signaling inhibitors that are capable of protecting cochlear HCs from high-dose ototoxic damage. Some of these protectants provided better protection than several previously described oto- protectants. We now propose to evaluate the most effective of these compounds in vivo, using a single, invariant model of noise-induced hearing loss in animals, so that the interventions can be strictly compared. We will also evaluate known HC protectants to provide benchmarks. This will allow us to identify optimal compounds for further development as pharmacological interventions in humans. Methodology: Studies will be performed using in vivo studies of noise damage to the cochlea, with intracochlear delivery of HC protectants beginning immediately after exposure. We will use a well- established mouse model of noise damage, delivery of compounds to cochlear perilymph with osmotic minipumps, serial auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) audiometry, and morphological evaluation of cochlear HCs and afferent nerve endings. Progress over the past period of funding: During the past period of funding, we developed a medium-throughput method for screening libraries of potential oto-protectants using the mammalian organ of Corti, the only tissue containing the damage-sensitive mammalian outer HCs. We identified several antioxidants and several cell-signaling pathway inhibitors that were highly effective, and had not previously been evaluated for HC protection. Using an electroporation model of organ of Corti transfection, we also screened more than 200 transcription factors for the ability to enhance HC regeneration caused by ATOH1 expression in nonsensory cells, discovering several novel factors with this ability. We discovered that gene therapy with espin1 dramatically enhanced stereocilia formation on regenerating HCs. Finally, we discovered a novel protective HC pathway mediated by ATP receptors that reduce activity in HCs at high stimulus levels, protecting them from noise damage. These studies resulted in 20 peer-reviewed publications to date. Clinical Relationship: The prevention and treatment of SNHL is of great importance to veterans and the VA. The effects of SNHL on veterans' quality of life are substantial. SNHL and tinnitus also account for more disability compensation in the VA than any other disorder, and rehabilitation costs are high. The proposed research is targeted at developing new and improved therapies for prevention and treatment of this important health problem.