Steroid Responsive Mechanisms in the Ear

描述（由申请人提供）：虽然糖皮质激素用于控制听力损失已经有几十年了，但人们对其控制下的耳细胞机制知之甚少。这些类固醇反应机制的知识对于我们理解正常耳蜗功能以及设计适当的临床治疗至关重要。因此，本研究的长期目标是充分表征类固醇驱动的耳部细胞和分子机制。这项研究的进展表明，MRL/MpJ-Fas1pr自身免疫小鼠的听力损失通过糖皮质激素强的松龙和矿皮质激素醛固酮调节耳蜗基因表达来响应类固醇治疗。因此，我们的工作假设是，耳朵中存在两种类固醇反应机制：由矿皮质激素受体介导的钠钾转运（稳态）基因的直接表达，以及由糖皮质激素受体介导的间接炎症基因抑制机制。计划中的研究将通过类固醇治疗来表征这些类固醇驱动的细胞和分子过程，选择性地分离这些受体，并测量它们控制的耳蜗稳态和炎症基因和蛋白质的变化。研究这些类固醇机制的具体目的是：

DESCRIPTION (provided by applicant): Although glucocorticoids have been employed for decades for control of hearing loss, little is known of the cellular mechanisms 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-Fas1pr autoimmune mouse responds to steroid treatments by regulating cochlear gene expression with both the glucocorticoid prednisolone and the mineralocorticoid aldosterone. Therefore, our working hypothesis is that two steroid-responsive mechanisms exist in the ear: a direct sodium and potassium transport (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 with steroid treatments that will selectively isolate these receptors and measure changes in cochlear homeostatic and inflammatory genes and proteins they control. The specific aims to investigate these steroid 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. The endocochlear potential will be measured in some experiments. 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.