SNTF immunostaining reveals previously undetected axonal pathology in traumatic brain injury.
SNTF immunostaining reveals previously undetected axonal pathology in traumatic brain injury.
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DOI：
10.1007/s00401-015-1506-0
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发表时间：
2016-01
影响因子：
12.7
通讯作者：
Smith DH
中科院分区：
文献类型：
--
作者：
Johnson VE;Stewart W;Weber MT;Cullen DK;Siman R;Smith DH
弥漫性轴索损伤(DAI)是重型颅脑损伤(TBI)的常见特征，也可能是轻度TBI或脑震荡的主要病理改变。白质在创伤瞬间的快速变形可导致机械故障和轴突细胞骨架的钙依赖蛋白分解，从而导致轴突运输中断。最近，在轻度颅脑损伤患者的血清中检测到α-II血影蛋白的蛋白分解片段“SNTF”，这预示着临床预后不良。然而，该片段是DAI的标志的直接证据尚未在脑损伤后的人类或轻度脑损伤的模型中得到证实。在这里，我们使用免疫组织化学(IHC)来检测重型和轻度脑外伤后脑组织中SNTF的变化。来自格拉斯哥脑损伤档案的人类重型脑损伤病例(存活7天；n=18)与年龄匹配的对照组(n=16)进行了比较。我们还观察了已建立的轻度脑创伤模型在伤后6小时、48小时和72小时与假手术对照组的脑组织。采用双重和三重免疫荧光标记，比较SNTF特异性IHC与DAI诊断标准淀粉样前体蛋白(APP)和其他轴突病理标志物包括非磷酸化神经丝-H(SMI-32)、神经丝-68(NF-68)和致密神经丝-介质(RMO-14)的表达。作为DAI的生物标志物，SNTF免疫反应阳性轴突在人重型脑损伤后和轻度脑损伤后的所有时间点都被观察到。有趣的是，SNTF发现了一个亚群的退化轴突，没有被运输中断的黄金标准标记APP检测到。虽然在人类严重脑外伤后，SNTF和APP之间有更多的轴突共定位，但SNTF阳性轴突的子集没有显示APP聚集。值得注意的是，在SNTF和不太丰富的神经丝亚型标记之间观察到了一些共同定位。然而，其他SNTF阳性轴突并不与任何其他标记物共定位。类似地，RMO-14和NF-68阳性轴突病变独立于SNTF和APP存在。这些数据表明，脑外伤后存在多种病理轴索表型，并为更全面地评估DAI的神经病理提供了洞察力。
Diffuse axonal injury (DAI) is a common feature of severe traumatic brain injury (TBI) and may also be a predominant pathology in mild TBI or “concussion”. The rapid deformation of white matter at the instant of trauma can lead to mechanical failure and calcium-dependent proteolysis of the axonal cytoskeleton in association with axonal transport interruption. Recently, a proteolytic fragment of alpha-II spectrin, “SNTF”, was detected in serum acutely following mild TBI in patients and was prognostic for poor clinical outcome. However, direct evidence that this fragment is a marker of DAI has yet to be demonstrated in either humans following TBI or in models of mild TBI. Here we used immunohistochemistry (IHC) to examine for SNTF in brain tissue following both severe and mild TBI. Human severe TBI cases (survival <7d; n=18) were compared to age-matched controls (n=16) from the Glasgow TBI archive. We also we examined brains from an established model of mild TBI at 6h, 48h and 72h post-injury versus shams. IHC specific for SNTF was compared to that of amyloid precursor protein (APP), the current standard for DAI diagnosis and other known markers of axonal pathology including non-phosphorylated neurofilament-H (SMI-32), neurofilament-68 (NF-68) and compacted neurofilament-medium (RMO-14) using double and triple immunofluorescent labelling. Supporting its use as a biomarker of DAI, SNTF immunoreactive axons were observed at all time-points following both human severe TBI and in the model of mild TBI. Interestingly, SNTF revealed a subpopulation of degenerating axons, undetected by the gold-standard marker of transport interruption, APP. While there was greater axonal co-localization between SNTF and APP after severe TBI in humans, a subset of SNTF positive axons displayed no APP accumulation. Notably, some co-localization was observed between SNTF and the less abundant neurofilament subtype markers. Other SNTF positive axons, however, did not co-localize with any other markers. Similarly, RMO-14 and NF-68 positive axonal pathology existed independent of SNTF and APP. These data demonstrate that multiple pathological axonal phenotypes exist post-TBI and provide insight into a more comprehensive approach to the neuropathological assessment of DAI.