Steroid Responsive Mechanisms in the Ear

耳朵中的类固醇反应机制

• 批准号: 7850280
• 负责人: DENNIS ROYAL TRUNE
• 金额: $ 21.38万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-17 至 2011-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7850280
• 关键词: Affinity; Aldosterone; Anti-Inflammatory Agents; Anti-inflammatory; Antigen-Antibody Complex; Antinuclear Antibodies; Audiometry; Auditory Brainstem Responses; Autoantibodies; Autoimmune Process; Binding; Clinical; Cochlea; Development; Dexamethasone; Disease; Dose; Ear; Electron Microscopy; Enzyme-Linked Immunosorbent Assay; Functional disorder; Gene Expression; Gene Expression Process; Genes; Genetic Transcription; Glucocorticoid Receptor; Glucocorticoids; Goals; Hematocrit procedure; Homeostasis; Immune; Inflammatory; Injection of therapeutic agent; Ion Transport; Ions; Knowledge; Labyrinth; Light; Liquid substance; Maintenance; Measures; Mediating; Methods; Mineralocorticoid Receptor; Mineralocorticoids; Molecular; Morphology; Mus; Pathway interactions; Potassium; Prednisone; Process; Proteins; RU-486; Regulation; Research; Research Design; Reverse Transcriptase Polymerase Chain Reaction; Role; Serum; Sodium; Spironolactone; Steroid Receptors; Steroid therapy; Steroids; Western Blotting; Work; cytokine; design; hearing impairment; inner ear diseases; interest; middle ear; mouse model; prednisolone; prevent; receptor; systemic autoimmune disease; transcription factor

DESCRIPTION (provided by applicant): Glucocorticoids (prednisone, methlyprednisolone, dexamethasone) have been employed for decades for control of hearing loss. However, little is known of the cellular and molecular processes of the ear that are under their control. Knowledge of these steroid-responsive mechanisms is critical for our understanding of normal cochlear function, as well as the design of appropriate clinical therapies. Therefore, the long term goal of this research is to fully characterize the steroid-driven cellular and molecular mechanisms of the ear. Progress on this study has shown that hearing loss in the MRL/MpJ-Faslpr autoimmune mouse responds to both the glucocorticoid prednisolone and the mineralocorticoid aldosterone. Furthermore, studies have shown glucocorticoids bind with equal affinity to both the glucocorticoid receptor and the mineralocorticoid receptor, thus regulating cochlear gene expression via immune suppression and ion homeostasis, respectively. Therefore, our working hypothesis is that two steroid-responsive mechanisms exist in the ear: a direct sodium and potassium transport (ion homeostatic) gene expression mediated by the mineralocorticoid receptor, and an indirect inflammatory gene suppression mechanism mediated by the glucocorticoid receptor. The planned studies will characterize these steroid driven cellular and molecular processes in the ear with steroid treatments that will functionally isolate the receptors and measure the ion homeostaticand inflammatory gene expression they control. The specific aims to investigate these steroid driven mechanisms of the ear are: Aim 1: Determine the dose-dependent control of inner ear ion homeostatic and inflammatory gene expression by the mineralocorticoid aldosterone and the glucocorticoid prednisolone. Aim 2: Determine the most effective control of both inner ear ion homeostatic and inflammatory gene expression processes by combination doses of the two steroids. Aim 3: Determine which cochlear cellular and molecular functions are mediated by each steroid receptor. Aim 4: Determine if effective inner ear homeostatic and anti-inflammatory gene expression can be induced by middle ear steroid delivery. In all studies, 1) inner ear function will be assessed by auditory brainstem response audiometry and endocochlear potential; 2) inner ear morphology will be assessed by light and electron microscopy; 3) systemic autoimmune disease will be assessed by serum immune complexes, hematocrits, and antinuclear antibodies; 4) cochlear specific autoantibodies will be assessed with ELISA, and 5) steroid-mediated cochlear gene products will be assessed with ELISA, Western blot, cytokine RNA expression, and quantitative RT-PCR. The results from these studies will provide new findings regarding the cellular and molecular mechanisms of the ear that are under the control of steroids. This also will lay important groundwork for the potential development of steroid therapies more effective than those currently employed. A study is proposed to evaluate the mechanisms by which steroids control the maintenance of inner ear homeostasis. Studies are designed to better understand the role of glucocorticoids and mineralocorticoids in normal inner ear gene expression, and how steroid treatments may be operating to reverse hearing loss. Mouse models (MRL/lpr) with autoimmune inner ear disease, a steroid responsive disorder, will be employed to differentiate the ion homeostasis and immune suppressive functions of steroids and the efficacy of the two steroid classes combined. Finally, the functional impact of middle ear injections versus systemic delivery will be compared to determine the ability of each method to control glucocorticoid and mineralocorticoid receptor-mediated gene expression in the cochlea. Of particular interest are immune suppression of inflammatory cytokines and related transcription factors compared to the regulation of ion transport pathways that control fluid homeostasis.

描述(申请人提供)：糖皮质激素(泼尼松、甲基强的松龙、地塞米松)用于控制听力损失已有数十年的历史。然而，人们对它们控制下的耳朵的细胞和分子过程知之甚少。对这些激素反应机制的了解对于我们理解正常的耳蜗功能以及设计适当的临床治疗方法是至关重要的。因此，这项研究的长期目标是充分描述类固醇驱动的耳朵的细胞和分子机制。这项研究的进展表明，MRL/MPJ-Faslpr自身免疫性小鼠的听力损失对糖皮质激素强的松龙和盐皮质激素醛固酮都有反应。此外，研究表明，糖皮质激素与糖皮质激素受体和盐皮质激素受体具有同等的亲和力，从而分别通过免疫抑制和离子稳态来调节耳蜗基因的表达。因此，我们的工作假设是，耳朵中存在两种类固醇反应机制：由盐皮质激素受体介导的直接钠钾转运(离子稳态)基因表达，以及由糖皮质激素受体介导的间接炎症基因抑制机制。计划中的研究将用类固醇治疗来表征这些类固醇驱动的细胞和分子过程，这些过程将从功能上分离受体，并测量它们控制的离子稳态和炎症基因的表达。目的1：研究糖皮质激素对内耳离子、动态平衡和炎症基因表达的剂量依赖性调控。目的2：确定两种类固醇的联合剂量对内耳离子稳态和炎症基因表达过程的最有效控制。目的3：确定每个类固醇受体介导的耳蜗细胞和分子功能。目的：探讨中耳注射类固醇能否诱导有效的内耳内环境平衡和抗炎基因表达。在所有研究中，1)将通过听性脑干反应测听和耳蜗管内电位来评估内耳功能；2)将通过光学和电子显微镜来评估内耳形态；3)将通过血清免疫复合物、血细胞和抗核抗体来评估系统性自身免疫性疾病；4)将通过ELISA法评估耳蜗特异性自身抗体；以及5)将通过ELISA法、Western印迹、细胞因子RNA表达和定量RT-PCR来评估类固醇介导的耳蜗基因产物。这些研究的结果将提供关于耳朵在类固醇控制下的细胞和分子机制的新发现。这也将为开发比目前使用的更有效的类固醇疗法奠定重要的基础。有人建议进行一项研究，以评估类固醇控制内耳内环境平衡的机制。研究旨在更好地了解糖皮质激素和盐皮质激素在正常内耳基因表达中的作用，以及类固醇治疗如何逆转听力损失。利用自身免疫性内耳疾病(一种激素反应性障碍)的小鼠模型(MRL/LPR)来区分类固醇的离子稳态和免疫抑制功能以及这两类类固醇的联合疗效。最后，将比较中耳注射和全身注射对功能的影响，以确定每种方法控制糖皮质激素和盐皮质激素受体介导的耳蜗基因表达的能力。特别令人感兴趣的是免疫抑制炎性细胞因子和相关的转录因子，而不是调节控制液体动态平衡的离子运输途径。