TRPV4通道在慢性高眼压视网膜神经节细胞损伤中的作用及机制研究

Glaucoma is the second leading cause of blindness, which is resulted from apoptotic death of retinal ganglion cells (RGCs). However, the mechanisms underlying RGC apoptosis are still not completely clarified. Transient receptor potential vanilloid 4 (TRPV4) channel is a non-selective cation channel, which could be activated by mechanical stimulation. Even though TRPV4 channels are widely expressed and distributed in retina, the effects of these channels on RGC apoptosis in glaucoma retina are largely unknown. Our preliminary results showed that in a rat chronic ocular hypertension (COH) model, TRPV4 channel protein expression was increased in retinas, and blockade of TRPV4 channels could reduce the number of apoptotic RGCs, suggesting that TRPV4 channels may be involved in RGC damage in glaucoma retinas. Therefore, our hypothesis is that TRPV4 channels are activated in glaucoma retina, which contributes to RGC apoptosis. In the proposed research, based on our previous studies, we aim to explore the effects and mechanisms of activated TRPV4 channels on RGC hyper-excitability, as well as Müller cell reactivation and pro-inflammatory factor release, so as to investigate the cellular and molecular mechanisms underlying the contribution of TRPV4 channels to RGC apoptosis in experimental glaucoma. Multi-disciplinary approaches, such as patch-clamp recordings, calcium image, Western blot, TUNEL apoptotic assess, will be employed. Our prospective research achievements would provide a scientific basis for illuminating the mechanisms of RGC injury and for effectively prevention and cure of glaucoma.

视网膜神经节细胞（RGC）凋亡是青光眼不可逆致盲的根本原因，其机制至今仍不是很明确。压力敏感的TRPV4通道在视网膜有广泛的分布，然而在青光眼病理过程中，TRPV4通道的变化及其在青光眼RGC损伤中的作用还不清楚。我们的预实验结果发现，慢性高眼压大鼠视网膜TRPV4通道蛋白表达量上调，且阻断TRPV4通道可减少慢性高眼压大鼠RGC的凋亡，提示TRPV4通道可能在青光眼RGC凋亡中有重要作用。因此，本项目拟利用膜片钳电生理、钙成像、Western blot、凋亡检测等多种生物学研究方法，深入研究TRPV4通道在慢性高眼压RGC凋亡中的作用，并从RGC的过度兴奋、Müller细胞激活及炎症因子释放等方面探究其作用机制，以验证我们关于青光眼病理过程中视网膜TRPV4通道被激活，并参与青光眼RGC凋亡的假说，从而补充和完善青光眼RGC损伤的机制，并为青光眼的治疗提供新的可能的临床靶点。

视网膜神经节细胞（RGC）凋亡是青光眼不可逆致盲的根本原因，其病理进程至今仍不是很明确。以往的研究表明机械力敏感的TRPV4通道在视网膜中分布广泛，且持续性激活TRPV4通道可以引起RGC凋亡，然而其引起RGC凋亡的作用机制仍不明确。我们的研究发现TRPV4通道在慢性高眼压大鼠表达量升高，且激活TRPV4通道参与高眼压引起的RGC凋亡和视功能损伤。进而我们对其损伤作用的机制进行研究，发现TRPV4通道在Müller细胞中功能性表达，且玻璃体腔注射TRPV4通道的激动剂可通过JAK2/STAT3/ NF-kB引起Müller细胞的激活和炎症因子TNF-α的释放。进一步研究发现，TRPV4通道激活可以引起RGC中1型TNF受体表达量增加，且施加TNF-α的中和抗体可降低由于TRPV4通道激活后引起的RGC凋亡。综上，本研究表明激活TRPV4通道可以通过激活Müller细胞，促进炎症因子TNF-α释放，同时上调RGC中1型TNF受体表达，共同参与青光眼RGC凋亡。本研究探索青光眼一种新病理机制，为青光眼的临床干预提供了新的可能靶点。