BMMSC外泌体传递miR-21调控小胶质细胞极化保护视网膜缺血再灌注损伤的机制研究

The retina ischemia-reperfusion (I/R) injury is the critical pathogenic mechanism of many important blinding eye diseases, which are the lack of effective treatment at present. Microglia polarization mediated inflammatory reaction plays an important role in the I/R secondary neuronal cell death. In our previous research, in the I/R model, increased miR – 21 in bone marrow mesenchymal stem cells (BMMSCs)-derived exosomes was found, and BMMSCs-derived exosomes can restrain the microglia activation and protect retinal damage. Inhibition of miR-21, BMMSCs exosomes showed less protective effect for retina I/R injury. So we put forward the hypothesis: BMMSCs-derived exosomes can deliver miR - 21 as the key factor to target protein PDCD4, as to regulate microglia polarization signal, reduce inflammation toxicity and protect the retina neural cell damage. To verify this hypothesis, we will establish the mouse retina I/R model in vivo and microglia oxygen deprived of reperfusion (OGDR) model in vitro, based on genetic, molecular and cellular level, discover how BMMSCs-derived exosomes deliver miR-21 to achieve immunomodulation mediated neuroprotection. Hope that through this project, we will find a new target for retinal I/R injury protection and a new direction for developing important blinding eye disease treatment.

视网膜缺血再灌注（I/R）损伤是许多重要致盲眼病的关键致病机制，目前缺乏有效治疗手段。小胶质细胞极化介导的炎症反应是I/R继发神经细胞死亡的重要环节。我们前期研究发现，I/R模型中，骨髓间充质干细胞（BMMSCs）外泌体miR-21含量增多，并能在体内抑制小胶质细胞活化，保护视网膜损伤。抑制miR-21后BMMSCs外泌体的视网膜保护作用明显减弱。因此我们提出设想：BMMSCs外泌体中的miR-21是关键因子，可能经由其靶蛋白PDCD4，调控小胶质细胞极化信号，减轻炎症毒性，保护视网膜神经细胞损伤。为了验证这一设想，我们将通过建立小鼠视网膜I/R模型及体外小胶质细胞氧糖剥夺再灌注（OGDR）模型，从基因、分子和细胞水平，探讨BMMSCs通过外泌体传递miR-21，实现免疫调节介导的神经保护作用机制。希望通过此课题研究找到视网膜I/R损伤保护的新靶点，为重要致盲眼病的治疗找到新方向。

视网膜缺血再灌注（ischemia reperfusion, I/R）损伤是许多重要致盲眼病的重要致病机制，其中小胶质细胞活化介导的炎症反应是I/R继发神经细胞死亡的关键。我们建立了小鼠视网膜I/R模型及体外小胶质细胞氧糖剥夺再灌注模型，将牙髓来源的间充质干细胞进行肿瘤坏死因子-α预刺激，通过从基因、分子和细胞水平，证实其分泌外泌体能通过miR-21/PDCD4通路，调控小胶质细胞活化，保护视网膜节细胞损伤作用。同时体外实验发现，乳脂肪球表皮生长因子8(milk-fat globule-epidermal growth factor 8,MFG-E8)抑制淀粉样蛋白Aβ42诱导的小胶质细胞分泌cathelicidin相关抗菌肽，对阿尔兹海默病相关神经炎症病变有一定的保护作用。淀粉样蛋白Aβ42诱导下小胶质细胞分泌刺激因子，对星型胶质细胞A1极化有激活作用，且MFG-E8可以抑制星型胶质细胞A1极化。从而为视网膜I/R损伤保护的新靶点发现提供实验支持。