The Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical University, Wenzhou 325027, China.
Department of Ophthalmology, Dazhou Central Hospital, Dazhou, Sichuan 635000, China.
Neuroscience. 2021 Jun 15;465:71-84. doi: 10.1016/j.neuroscience.2021.04.014. Epub 2021 Apr 23.
In adult mammals, axon regeneration is limited within the lesion site after injury to the optic nerve. Changes in the microenvironment of lesion sites play an important role in retinal ganglion cells (RGCs) axon regeneration along with other intrinsic factors. In this study, the effect of the lesion site on the microenvironment and axon growth was evaluated using a refined optic nerve crush (ONC) injury model, in which the injury range was extended compared to classical injury. The number of regenerated axons labeled anterogradely with cholera toxin B fragment (CTB) was significantly increased in the long-range crush injury (LI) group compared to the ONC group at distances of 500, 1000 and 1500 µm from the initial site of the injury. These data confirmed that RGC axons can regenerate inside the lesion site. Immunofluorescence and proteomic analysis showed that the microenvironment at the lesion site was highly heterogeneous. The levels of myelin-associated inhibitors, chondroitin-sulfate proteoglycans (CSPGs) and other axon growth inhibitors decreased inside the lesion site compared to the posterior segment of the optic nerve lesion site. The expression of multiple lysosome-related enzymes, metabolic inhibitors including cholesterol esterase, cathepsin B, D, Z and arylsulfatase B (ARSB) were significantly increased inside the lesion site for the LI group compared to the normal optic nerves. Our results suggest that the model of long range optic nerve injury is more useful towards understanding the lesion microenvironment and the endogenous regeneration of RGCs. Also, we showed that myelin and neurocan (a CSPG) are differently expressed in the optic nerve between the interior and posterior lesion sites and may explain why axons cannot reach the brain through the lesion site.
在成年哺乳动物中，视神经损伤后，轴突再生仅限于损伤部位。病变部位微环境的变化以及其他内在因素在视网膜神经节细胞（RGC）轴突再生中起着重要作用。在这项研究中，使用改良的视神经挤压（ONC）损伤模型评估了病变部位对微环境和轴突生长的影响，与经典损伤相比，该模型扩展了损伤范围。与 ONC 组相比，在距离损伤初始部位 500、1000 和 1500 µm 的长距离挤压损伤（LI）组中，用霍乱毒素 B 片段（CTB）顺行标记的再生轴突数量显著增加。这些数据证实了 RGC 轴突可以在病变部位内再生。免疫荧光和蛋白质组学分析表明，病变部位的微环境高度异质。与视神经病变后段相比，病变部位的髓鞘相关抑制剂、硫酸软骨素蛋白聚糖（CSPGs）和其他轴突生长抑制剂的水平降低。与正常视神经相比，LI 组病变部位的多种溶酶体相关酶、代谢抑制剂（包括胆固醇酯酶、组织蛋白酶 B、D、Z 和芳基硫酸酯酶 B（ARSB））的表达显著增加。我们的结果表明，长距离视神经损伤模型更有助于理解病变微环境和 RGC 的内源性再生。此外，我们还表明，髓鞘和神经粘蛋白（一种 CSPG）在视神经内部和后部病变部位的表达不同，这可能解释了为什么轴突不能通过病变部位到达大脑。
