水杨酸抑制COX-1导致耳蜗螺旋神经节细胞损伤

Salicylic acid （aspirin）has a good anti-inflammatory effect, but the ototoxicity limits its wide application. Recent clinical studies have found, long-term large dose use of salicylic acid, can lead to permanent hearing loss, basic research has also confirmed that the irreversibility of salicylic acid induced apoptosis of spiral ganglion cells (SGN), but the mechanism is unknown. It has been Known salicylic acid exert their pharmacological effects by inhibiting cyclooxygenase (Cox), and can suppress the two kinds of subtypes Cox-1 and Cox-2, but is still not clear what kind of way is the main cause of ototoxicity. Cox-1, Cox-2 is widely expressed in the cochlea, and in other causes of sensorineural hearing loss, expression of them will change accordingly. We pre verified, Cox-2 Inhibitor Celecoxib does not lead to animal ABR threshold change significantly, while the Cox-1 inhibitor SC-560 can lead to elevated ABR thresholds. Thus we hypothesized that salicylate ototoxicity were due to the suppressed of the Cox-1. The study will use several different types of Cox inhibitors, with cell culture In vitro and experiment animal in vivo, to further confirmed the damage of spiral ganglion cells were caused by inhibition of Cox-1 induced by salicylic acid, which eventually leading to the permanent hearing loss.The accomplishment of this project will help to further reveal the mechanism of salicylate ototoxicity, as far as possible to avoid the occurrence of this drug deafness.

水杨酸(阿司匹林)具有良好的抗炎作用，但耳毒性等副作用限制了其应用范围。近期临床研究发现，长期大剂量使用水杨酸可导致永久性耳聋，基础实验也证实水杨酸不可逆性诱发螺旋神经节细胞（SGN）凋亡，但机制不明。已知水杨酸通过抑制环氧化酶（COX）发挥药理作用，并可同时抑制COX-1和COX-2两种亚型，但尚不明确何种途径是耳毒性的主因。COX-1、COX-2在耳蜗中广泛表达，并在其它原因导致的感音神经性聋中，表达会发生相应变化。我们前期研究证实，COX-2抑制剂塞来昔布并不导致动物ABR阈值明显改变，而COX-1抑制剂SC-560却能导致ABR阈值升高。由此我们推测水杨酸耳毒性与COX-1抑制有关。本课题拟采用不同类型COX抑制剂，通过细胞培养和在体动物两种途径，证实水杨酸通过抑制COX-1诱发SGN凋亡，导致永久性聋。本项目的完成将有助于进一步揭示水杨酸耳毒性机制，尽可能规避药物性聋的发生。

我们前期预实验提示，COX-2抑制剂塞来昔布并不导致动物ABR阈值明显改变，由此我们假设水杨酸耳毒性与COX-1抑制有关。通过细胞培养和在体动物两种途径，发现水杨酸无法通过抑制COX-1诱发SGN凋亡，从而导致永久性聋。研究的过程中引入了耳蜗发育相关的蛋白及机制研究。蛋白方面，探究了C57BL/6J小鼠耳蜗组织中高迁移率族蛋B1（HMGB1）的分布情况，即HMGB1在正常小鼠耳蜗中不同细胞中的表达有差异，为研究HMGB1在内耳疾病中的作用提供基础。机制研究部分分为耳蜗发育和毛细胞损伤两部分。其中耳蜗发育部分阐述了Limk1，Limk2，Pax2，Sox2以及Prox1发育相关基因的作用，即Limk1和Limk2的丢失并未影响耳蜗的整体发育，与中枢神经系统中的作用相比，Limk基因在耳蜗的发育中起着不同的作用；Pax2，Sox2和Prox1转录因子在发育中的听觉和前庭感觉器官中的不同表达模式表明它们在感觉上皮细胞的发育中起不同作用，并且可能有助于塑造各自的感音结构。毛细胞损伤部分，关注胎牛血清的抗凋亡作用，即胎牛血清FBS在新霉素暴露后通过维持线粒体蛋白水平，以及氧化基因表达的平衡，防止ROS的积累，从而抑制HEI-OC-1细胞的凋亡。本项目的完成将有助于进一步揭示耳蜗发育的相关机制，并推动药物耳毒性的研究进展。