Neuroimmunology Group, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, United Kingdom.
Exp Neurol. 2012 Feb;233(2):836-48. doi: 10.1016/j.expneurol.2011.12.010. Epub 2011 Dec 16.
Both the neural and glial components of the neuromuscular junction (NMJ) have been identified as potential sites for anti-ganglioside antibody (Ab) binding and complement-mediated injury in murine models for the human peripheral nerve disorder Guillain-Barré syndrome (GBS). Some patients suffering from the acute motor axonal neuropathy (AMAN) forms of GBS recover very rapidly from paralysis; it has been proposed that in these cases the injury was restricted to the distal motor axons and nerve terminals (NTs) which are able to regenerate over a very short time-frame. To test this hypothesis, the ventral neck muscles of mice (n=45) expressing cytosolic fluorescent proteins in their axons (CFP) and Schwann cells (GFP) were subjected to a single topical application of anti-ganglioside Ab followed by a source of complement. Group A (n=15) received Ab that selectively bound to the NTs, group B (n=15) received Abs that bound both to the NTs and the perisynaptic Schwann cells (pSCs) and group C (control animals; n=15) only received complement. Evolution of the injury was documented by in vivo imaging, and following euthanasia the muscles were reimaged ex vivo both quantitatively and qualitatively, either immediately, or after 1, 2, 3 or 5 days of regeneration (each n=3 per group). Within 15 minutes of complement application, a rapid loss of CFP overlying the NMJ could be seen; in group A, the GFP signal remained unchanged, whereas in group B the GFP signal was also lost. In group C no changes to either CFP or GFP were observed. At 24 h, 6% of the superficial NMJs in group A and 12% of the NMJs in group B exhibited CFP. In both groups, CFP returned within the next five days (group A: 93.5%, group B: 94%; p=0.739), with the recovery of CFP being preceded by a return of GFP-positive cells overlying the NMJ in group B. Auxiliary investigations revealed that the loss of CFP at the NMJ correlated with a loss of NT neurofilament immuno-reactivity and a return of CFP at the NMJ was accompanied by a return of neurofilament. In ultrastructural investigations, injured NTs were electron lucent and exhibited damaged mitochondria, a loss of filaments and a loss of synaptic vesicles. The examination of muscles after five days of regeneration revealed physiological NT-profiles. The results described above indicate that following a single anti-ganglioside Ab-mediated and complement-mediated attack, independent of whether there are healthy and mature perisynaptic Schwann cells overlying the NMJ, the murine NT is capable of recovering both its architectural and axolemmal integrity very rapidly. This data supports the notion that an equivalent mechanism may account for the rapid recovery seen in some clinical cases of AMAN.
神经肌肉接头（NMJ）的神经和神经胶质成分已被确定为潜在的抗神经节苷脂抗体（Ab）结合和补体介导损伤的部位，在人类周围神经疾病格林-巴利综合征（GBS）的小鼠模型中。一些患有急性运动轴索性神经病（AMAN）形式的 GBS 的患者从瘫痪中迅速恢复；有人提出，在这些情况下，损伤仅限于运动轴突和神经末梢（NTs），这些轴突和神经末梢能够在非常短的时间内再生。为了验证这一假设，表达轴突（CFP）和施万细胞（GFP）胞质荧光蛋白的小鼠（n=45）的颈部腹侧肌肉接受了单次局部应用抗神经节苷脂 Ab 治疗，然后给予补体来源。A 组（n=15）接受选择性结合 NT 的 Ab，B 组（n=15）接受结合 NT 和神经节周 Schwann 细胞（pSCs）的 Ab，C 组（对照动物；n=15）仅接受补体。通过体内成像记录损伤的演变，安乐死后立即或再生 1、2、3 或 5 天后，对肌肉进行体外定量和定性再成像（每组 n=3）。补体应用后 15 分钟内，NMJ 上可见 CFP 迅速丢失；在 A 组中，GFP 信号保持不变，而在 B 组中，GFP 信号也丢失。在 C 组中，CFP 或 GFP 均未观察到变化。在 24 小时时，A 组中 6%的浅表 NMJ 和 B 组中 12%的 NMJ 表现出 CFP。在两组中，CFP 在接下来的五天内恢复（A 组：93.5%，B 组：94%；p=0.739），B 组 NMJ 上 GFP 阳性细胞的恢复先于 CFP 的恢复。辅助研究表明，NMJ 上 CFP 的丢失与 NT 神经丝免疫反应性的丢失有关，而 NMJ 上 CFP 的恢复伴随着神经丝的恢复。在超微结构研究中，受损的 NT 呈电子透明状，表现出受损的线粒体、细丝丢失和突触小泡丢失。再生 5 天后肌肉的检查显示出正常的 NT 形态。上述结果表明，在单次抗神经节苷脂 Ab 介导和补体介导的攻击后，无论 NMJ 上方是否有健康成熟的神经节周 Schwann 细胞，鼠 NT 都能够非常迅速地恢复其结构和轴膜完整性。该数据支持这样一种观点，即一种等效机制可能解释了一些 AMAN 临床病例中观察到的快速恢复。
