雷帕霉素内耳缓释给药通过激活自噬和抗氧化应激防治老年性聋及机制探讨

Age-related hearing loss (ARHL) is serious sensory deficit with high incidence rate. Our preliminary study indicated that rapamycin could effectively ameliorate age-related hearing loss. After treatment, the ratio of autophagy related protein LC3BⅡ/ LC3BⅠincreased obviously. Rapamycin may enhance the anti-oxidative capacity by specifically blocking PI3K/Akt/mTORC1 and then activating FoxO3a. Meanwhile, Rapamycin can cover the shortage of pure antioxidant therapy by activating autophagy and degrading oxidative damage product. However, systemic administration of rapamycin may lead lots of side effect. In this study, we try to use inner ear drug delivery, which can deliver high drug concentration in the inner ear and reduce the systemic side effects. Poloxamer 407 gel can control drug volume loss down the eustachian tube. Multivesicular liposomes could be an effective sustained release strategy. Based on our research techniques of the inner ear pharmacokinetics including sequential sampling perilymph from the lateral semicircular canal, we investigate the entry routes, timed-release formulations and how drugs distribute into the inner ear. We aim to explore a safe, effective, and slight side effect way to ameliorates age-related hearing loss. This project combines medicine and pharmacy, and emphasizes the cross-subject. We hope to provide new target and drug-delivery way for prevention and treatment of age-related hearing loss.

老年性聋发病率高，危害广泛，我们初步研究发现雷帕霉素可有效延缓C57/BL6小鼠的年龄相关性下降，用药后，自噬相关蛋白LC3BⅡ/ LC3BⅠ的比值增加，螺旋神经元自噬斑点明显增多。雷帕霉素可能通过特异性阻断PI3K/Akt/mTORC1，激活FoxO3a 活性，增强内耳细胞抗氧化能力；同时，雷帕霉素激活自噬，降解已经形成的氧化损伤产物，弥补单纯抗氧化治疗的局限。然而，考虑到全身给药的副作用，本研究探索内耳精确给药。内耳给药能在内耳达到较高浓度的同时，可降低全身副作用。泊洛沙姆407温敏凝胶可以减少药物经过咽鼓管的流失，与缓释的多囊脂质体包药技术结合，具有良好缓释效果，并结合我们前期外半规管外淋巴连续取样等内耳药代动力学研究技术，研究药物进入内耳的途径及分布代谢，探索安全、有效、副作用小的防治策略，本项目为医药结合项目，突出学科交叉，为老年性聋的防治提供新的作用靶点和给药方式。

背景：老年性聋发病率高，危害广泛。雷帕霉素可通过增强内耳细胞抗氧化能力，同时激活自噬有效延缓C57/BL6小鼠的年龄相关性听力下降。然而由于其全身给药的副作用，本研究探索内耳精确给药，研究药物进入内耳的途径及分布代谢，探索安全、有效、副作用小的防治策略。.主要内容：1.检测老年性聋小鼠螺旋神经元细胞（SGNs)自噬、氧化应激标志物水平。2.探索mTOR信号通路在老年性聋发生中的作用。3.探索雷帕霉素调控mTOR信号通路在延缓老年性聋的发生中的作用。4.探讨骨髓间充质干细胞外泌体（BM-MSC exo)在体外通过上调自噬对HEI-OC1细胞起保护作用。.重要结果及关键数据：1.老年性聋小鼠较对照组小鼠SGNs氧化应激水平升高，自噬水平下降。2.mTOR蛋白活性是自噬负性调节因子，其活化程度可反映自噬水平，老年性聋小鼠SGNs mTOR信号通路活性较对照组升高。3.雷帕霉素通过抑制小鼠SGNs细胞的mTOR活性，活化SGNs内的自噬流来延缓年龄相关性听力下降。4.BM-MSC exo在体外可调节HEI-OC1细胞氧化应激损伤导致的自噬水平下降，初步展现其应用于老年性聋防治的前景。.科学意义：本项目为医药结合项目，突出学科交叉，为老年性聋的防治提供新的作用靶点和给药方式。