Retinal ganglion cell survival after severe optic nerve injury is modulated by crosstalk between JAK/STAT signaling and innate immune responses in the zebrafish retina. Retinal ganglion cell survival after severe optic nerve injury is modulated by crosstalk between JAK/STAT signaling and innate immune responses in the zebrafish retina

The death of retinal ganglion cells(RGC) after the damage on optic nerve as a result of high intraocular pressure is the main reason of the irreversible blindness in glaucoma patients ,and mammals have very limited ability of maintaining the RGCs after optic nerve injury.Zebrafish,however,possess the ability of keep most RGCs from death after optic nerve injury. The purpose of this study is to determine which gene or pathway mediate the RGC survival mechanism underlying.It is observed JAK/STAT signaling pathway as well as the innate immune response is activated after optic nerve injury(in this study,optic nerve transection).Pharmacological inhibition of JAK/STAT by intravitreal(IV) injection of JAK inhibitor,P6,induced the reduction of RGC survival while both local and systemic immune suppressor application result in the rescue of RGC survival.Moreover,phospho-STAT3(pSTAT3),which is an evidence of STAT3 activation,demonstrated elevation of expression level after ONT,and the trend of pSTAT3 expression change is consistent with the RGC survival rate change .JAK inhibition reduced pSTAT3 expression level and immune suppressor application elevated the pSTAT3 expression level on RGCs. In summary,these data suggested JAK/STAT signaling pathway crosstalk with innate immune response create a dynamic balance in the mechanism of RGC survival.Interestingly,innate immune response which was used to be considered promoting tissue repair in other studies,proved to be suppressing RGC survival in this study.These data could be used as reference for future direction of neuroprotection in glaucoma treatment. Overall design: RNA-seq from FACS-purified retinal ganglion cells post optic nerve transection and uninjured contralacteral eyes as control at 3 timepoints: 6,12 and 24 hours post injury(hpi). ONT+ for injured samples and ONT- for control

高眼压引发视神经损伤后，视网膜神经节细胞（retinal ganglion cells, RGC）死亡是青光眼患者发生不可逆失明的核心诱因，而哺乳动物在视神经损伤后维持RGC存活的能力极为有限。但斑马鱼却可在视神经损伤后避免绝大多数RGC死亡。本研究旨在明确介导该RGC存活机制的基因或通路。
研究观察到，视神经损伤（本研究中为视神经横断术，optic nerve transection, ONT）后，JAK/STAT信号通路与固有免疫应答均被激活。通过玻璃体内（intravitreal, IV）注射JAK抑制剂P6对JAK/STAT通路进行药理学抑制，会降低RGC的存活率；而局部或全身应用免疫抑制剂则可挽救RGC的存活。此外，作为STAT3激活标志物的磷酸化STAT3（phospho-STAT3, pSTAT3）在ONT术后表达水平升高，其表达变化趋势与RGC存活率的变化完全一致。JAK抑制会降低pSTAT3的表达水平，而免疫抑制剂的应用则可上调RGC中pSTAT3的表达水平。
综上，上述数据表明，JAK/STAT信号通路与固有免疫应答相互串扰，在RGC存活机制中形成动态平衡。值得注意的是，既往研究中被认为可促进组织修复的固有免疫应答，在本研究中被证实会抑制RGC存活。本研究数据可为青光眼治疗领域神经保护的后续研究方向提供重要参考。
整体实验设计：分别在损伤后6、12、24小时三个时间点，对经荧光激活细胞分选（FACS）纯化的视网膜神经节细胞进行RNA测序，以未损伤的对侧眼作为对照。损伤组记为ONT+，对照组记为ONT-