TGFβ1相关信号通路对人工耳蜗植入后蜗内纤维化的影响

After cochlear implantation (CI) fibrosis in cochlear may lead to residual hearing loss and difficulty for re-implantation, but the mechanism of fibrosis after CI is not clear. Group preliminary study found that after CI TGF beta 1 gene expression level, and is associated with postoperative hearing loss;Preliminary experiments further found that MMP2, MMP9 expression level also rise significantly, and MMP9 and TGF beta 1 were positively correlated.We hypothesized that CI after cochlear existence through the TGF beta 1 regulation of MMPs and regulation in the worm fibrosis mechanism.Therefore, on the basis of previous work, this research intends to further from multiple levels in the animal model of guinea pig CI validation implantation trauma of TGF beta 1, the influence of MMPs and other related signaling pathways expression level and fibrosis, the relationship between the inside and worm;In vitro model of observation after adjusting the TGF beta 1 level MMPs and fibrosis indexes of alpha SMA, FN expression changes, and observe could inhibit MMPs to block TGF beta 1 regulation of the downstream discussion can adjust the signal path control in the cochlear fibrosis process.This study is expected to clarify from the perspective of TGF beta 1 related signaling pathways within worm after CI fibrosis related molecular mechanism, and accordingly establish treatment strategies, has important scientific significance and application value.

人工耳蜗植入（CI）后蜗内纤维化会导致残余听力损失并阻碍再次植入，但目前蜗内纤维化的机制不清。课题组前期研究发现，CI 后TGFβ1基因表达上调，且与术后听力损失相关；预实验进一步发现MMP2、MMP9表达水平亦显著上调，且MMP9与TGFβ1呈正相关。我们推测CI后耳蜗存在通过TGFβ1调控MMPs进而调控蜗内纤维化的机制。因此，在前期工作基础上，本研究拟在豚鼠CI动物模型中进一步从多层面验证植入创伤对TGFβ1、MMPs等相关信号通路表达水平的影响以及与蜗内纤维化的关系；在体外模型中观察调节TGFβ1水平后MMPs和纤维化指标α-SMA、FN表达的变化，并观察能否通过抑制MMPs来阻断TGFβ1对下游的调控，探讨调节该信号通路能否控制蜗内纤维化进程。本研究有望从TGFβ1相关信号通路的角度阐明CI后蜗内纤维化相关分子机制，并据此建立治疗策略，具有重要科学意义和应用价值。

人工耳蜗植入（CI）后蜗内纤维化会导致残余听力损失并阻碍再次植入，但目前蜗内纤维化的机制不清。本项目建立并优化大鼠人工耳蜗植入动物模型，进行CI术后的耳蜗组织形态学研究，并完成了对CI术后大鼠耳蜗组织TGFβ1和MMP/TIMP信号通路的表达及干预情况的研究；增加了对巨噬细胞极化及IL-1β，TNF-α，IL-4相关因子的表达调控的研究，并增加了通过载地塞米松的聚己内酯（PCL）电极涂层实现蜗内抗炎、抗纤维化的应用基础研究。结果表明：大鼠CI术后鼓阶内纤维组织体积与术后听力损失存在明显的正相关性，动物术后听力的状况是耳蜗内创伤与纤维化程度在活体的直接反映。TGF-β1在耳蜗纤维组织中显著高表达，其下游调控的肌成纤维细胞标志物α-SMA及细胞外基质I型胶原蛋白在电极周围的增生组织中呈现强阳性表达，共同组成纤维化组织。MMPs及其内源性抑制物TIMP在纤维化组织内有表达，但MMPs在耳蜗纤维化组织中的表达是下调，而其抑制物TIMP表达增高，与原来预想的情况不同。CI术后有表型标志Arg-1 ，IL-10和CD206的M2极化的巨噬细胞黏附于电极表面。巨噬细胞在纤维化过程中分泌TGF-β1 ，IL-1β，TNF-α，IL-4等因子；在TGF-β1的诱导下，巨噬细胞或间充质细胞转变为肌成纤维细胞并产生细胞外基质，从而形成致密纤维组织。TGF-β1和巨噬细胞均在发病机制中具有关键作用。为了对TGF-β1和巨噬细胞进行调控从而减轻纤维化，本研究应用了一种电极涂层聚己内酯（PCL）来长期持续输送地塞米松（DEX）到耳蜗中；该涂层制作工艺简单，可保持电极本身的稳定性，具有良好的生物相容性及药物缓释性能。PCL-DEX涂层电极通过长期可控地输送DEX来调节巨噬细胞极化，抑制TGF-β1信号通路和IL-1β,TNF-α, IL-4等因子的表达来减少耳蜗内纤维化, 保护螺旋神节和毛细胞，从而提高听力，改善CI预后。而MMPs及其内源性抑制物TIMP表达变化暂无统计学差异。本研究从TGFβ1相关信号通路和巨噬细胞调控的角度阐明CI后蜗内纤维化相关分子机制，并据此建立治疗策略，具有重要科学意义和应用价值。