Dong Chaoling, Helton E Scott, Zhou Ping, Ouyang Xuan, d'Anglemont de Tassigny Xavier, Pascual Alberto, López-Barneo José, Ubogu Eroboghene E
a Neuromuscular Immunopathology Research Laboratory, Division of Neuromuscular Disease, Department of Neurology , University of Alabama at Birmingham , Birmingham , Alabama , United States of America.
b Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla , Seville , Spain.
Tissue Barriers. 2018;6(2):1-22. doi: 10.1080/21688370.2018.1479570. Epub 2018 Sep 5.
There is emerging evidence that glial-derived neurotrophic factor (GDNF) is a potent inducer of restrictive barrier function in tight junction-forming microvascular endothelium and epithelium, including the human blood-nerve barrier (BNB) in vitro. We sought to determine the role of GDNF in restoring BNB function in vivo by evaluating sciatic nerve horseradish peroxidase (HRP) permeability in tamoxifen-inducible GDNF conditional knockout (CKO) adult mice following non-transecting crush injury via electron microscopy, with appropriate wildtype (WT) and heterozygous (HET) littermate controls. A total of 24 age-, genotype- and sex-matched mice >12 weeks of age were injected with 30 mg/kg HRP via tail vein injection 7 or 14 days following unilateral sciatic nerve crush, and both sciatic nerves were harvested 30 minutes later for morphometric assessment by light and electron microscopy. The number and percentage of HRP-permeable endoneurial microvessels were ascertained to determine the effect of GDNF in restoring barrier function in vivo. Following sciatic nerve crush, there was significant upregulation in GDNF protein expression in WT and HET mice that was abrogated in CKO mice. GDNF significantly restored sciatic nerve BNB HRP impermeability to near normal levels by day 7, with complete restoration seen by day 14 in WT and HET mice. A significant recovery lag was observed in CKO mice. This effect was independent on VE-Cadherin or claudin-5 expression on endoneurial microvessels. These results imply an important role of GDNF in restoring restrictive BNB function in vivo, suggesting a potential strategy to re-establish the restrictive endoneurial microenvironment following traumatic peripheral neuropathies.
越来越多的证据表明，胶质细胞源性神经营养因子（GDNF）是紧密连接形成的微血管内皮和上皮中限制性屏障功能的有效诱导剂，包括体外培养的人血神经屏障（BNB）。我们试图通过电子显微镜评估他莫昔芬诱导的GDNF条件性敲除（CKO）成年小鼠在非横断性挤压损伤后坐骨神经辣根过氧化物酶（HRP）的通透性，以确定GDNF在体内恢复BNB功能中的作用，并设置合适的野生型（WT）和杂合子（HET）同窝对照。总共24只年龄、基因型和性别匹配且大于12周龄的小鼠，在单侧坐骨神经挤压后7天或14天经尾静脉注射30 mg/kg HRP，30分钟后收获双侧坐骨神经，通过光学显微镜和电子显微镜进行形态计量学评估。确定HRP可透过的神经内膜微血管的数量和百分比，以确定GDNF在体内恢复屏障功能的作用。坐骨神经挤压后，WT和HET小鼠中GDNF蛋白表达显著上调，而CKO小鼠中则被消除。到第7天，GDNF显著将坐骨神经BNB的HRP不可透过性恢复到接近正常水平，WT和HET小鼠在第14天完全恢复。在CKO小鼠中观察到明显的恢复延迟。这种作用不依赖于神经内膜微血管上的血管内皮钙黏蛋白或闭合蛋白-5的表达。这些结果表明GDNF在体内恢复限制性BNB功能中起重要作用，提示在创伤性周围神经病变后重建限制性神经内膜微环境的潜在策略。
