HO-1介导的螺旋器氧化损伤易感性差异机制研究

Aminoglycoside-induced cochlear ototoxicity causes hair cell(HC) loss and results in high-frequncy hearing impairment. The base of the cochlea is more vulnerable than the apex as seen in the generation of ROS caused by aminoglycosides. Our previous work found that Heme oxygenase-1 (HO-1) is most prominent with the biggest fold change among 96 oxidative relative genes analyzed using PCR arrays when comparing the apical and basal sensory epithelia in newborn rats.The level of HO-1 mRNA is much higher in the apical part than the basal part in new rats by.RT-PCR. However,both decreased dramatically in normal adult rats cochleae. While in karamycin-treated hearing loss rats, the level of HO-1 increases in both parts of the cochlea and the apical part remains higher. Further immumochemistry confirmed the distribution of HO-1 in Organ of Corti is mainly in supporting cells as well as in HCs in . Our study intends to explore the effect of upregulation/downregulation of HO-1 on ROS and mophology of Organ of Corti after the exposure to karamycin, using cultures of Organ of Corti and animal models. Further we try to investigate whether HO-1 and its metabolic by-product, carbon monoxide (CO), might protect against cute/ chronic inflammation and cell clearance in Organ of Corti, and how HO-1 interact with other ROS susceptibility related protein. Our study might contribute to elucidate the mechanism of how supporting cells effect cochlear hair cells under oxidant stress, and provide new insight of treatment of hearing loss.

氨基糖甙类抗生素具耳毒性，主要机制为氧化应激反应损伤耳蜗下段毛细胞，耳蜗不同部位存在受损敏感性差异；具体分子机制仍不明确。我们通过对比耳蜗上下段螺旋器的基因芯片筛选结果，发现HO-1基因在新生大鼠耳蜗上段表达量明显高于下段，均随年龄的增长显著下降。耳聋模型大鼠耳蜗HO-1基因表达量显著增加，上段明显高于下段；其蛋白主要分布于支持细胞。HO-1为经典的内源性抗氧化酶/热休克蛋白，是多系统疾病基因治疗研究的热点；它在螺旋器的效应机制尚不清楚。本研究拟明确HO-1在螺旋器细胞定位，利用耳毒性药物处理的螺旋器分段组织培养和耳聋模型，探索HO-1高/低表达对不同部位自由基形成、线粒体损伤、细胞形态与凋亡的影响，并观察HO-1及下游底物对炎症细胞因子等的调节作用，与易感性差异相关基因的相互作用，有助于深入理解支持细胞在耳蜗抗氧化损伤中影响听觉细胞存活关键机制；为耳聋的靶向药物治疗提供新的思路

氨基糖苷类抗生素对内耳有毒副作用，庆大霉素的耳毒性是由包括感觉毛细胞（HCs）在内耳细胞的损坏和死亡引起的。在这项研究中，我们使用RT²ProfilerPCR阵列筛选庆大霉素损伤前后的差异基因，旨在开发预防由庆大霉素引起的听力损失的候选靶点。我们发现在庆大霉素诱导的HCs死亡中，HO-1在耳蜗所有上调基因中具有最高的倍数变化（6.99倍）。另外，我们发现在HO-1在Corti器的支持细胞中表达。使用CoPPIX诱导HO-1可抑制庆大霉素诱导的HCs死亡，并降低活性氧（ROS）水平。此外，通过使用HO-1抑制剂ZnPPIX可以证明，CoPPIX的保护作用受HO-1的控制。此外，庆大霉素显著增加NF-E2相关因子2（Nrf2）的表达量，表明Nrf2 / HO-1信号通路可能参与调节与庆大霉素相关的耳毒性聋。总之，这些发现表明支持细胞通过HO-1诱导保护内耳免受庆大霉素诱导的HCs死亡。HO-1可以作为潜在候选基因，将在药物性耳聋的防治与治疗过程中起到关键作用，其激动剂CoPPIX或可成为治疗药物性耳聋的新药物。