Intracerebral expression pattern of various transported protein through axons and proinflammatory cytokines after fatal traumatic brain injury

本研究旨在建立弥漫性创伤性轴索损伤（diffusedtraumaticaxonalinjury，TAI）的法医学诊断新标志物、创伤性轴索损伤与缺氧性轴索损伤的鉴别诊断、损伤后时间间隔的估计方法。为此，我们用化学发光法检测了通过轴突转运的蛋白质如β-淀粉样前体蛋白（APP）、神经元特异性烯醇化酶（NSE）的脑内表达，以及促炎细胞因子如白细胞介素-8（IL-8）、肿瘤坏死因子-α（TNF-α）的表达。对头部损伤病例的胼胝体切片进行这些标记的免疫染色。APP和NSE免疫染色切片，两种模式的免疫反应性被确定在几个案件的头部损伤。第一种模式显示标记的轴突沿着白色物质束定向;第二种模式显示轴突不规则地分散。结果提示，第一型和第二型可能分别代表创伤性轴索损伤和继发性缺氧性轴索损伤。此外，NSE检测TAI比APP更敏感，因为NSE免疫染色可以检测存活超过2小时（APP ;超过9小时）的头部损伤病例中的轴突损伤。此外，IL-8和TNF-α免疫染色可以分别检测存活超过3天和4天的脑损伤病例的轴突损伤。我们的研究结果表明，胼胝体中促炎细胞因子如IL-8和TNF-α的免疫染色可能是一个新的有用的标记，估计创伤性轴索损伤后的时间间隔。

This research aimed to establish the following three methods ; (1) new forensic diagnostic markers for diffuse traumatic axonal injury (TAI), (2) differential diagnosis between traumatic axonal injury and hypoxic one, (3) estimation for time interval after injury. For this purpose, we immunohistochemically examined intracerebral expressions of transported proteins through axons such as β-amyloid precursor protein (APP), Neuron-specific enolase (NSE), and expressions of proinflammatory cytokines such as Interleukin-8 (IL-8), Tumor necrosis factor-α (TNF-α). Sections of the corpus callosum from cases of head injury were immunostained for those markers. On both APP and NSE immunostained sections, two patterns of immunoreactivity were identified in several cases of head injury. The first pattern showed that labeled axons were oriented along with white matter bundles ; the second demonstrated that the axons were scattered irregularly. Our results suggested that the first and second pattern may represent traumatic axonal injury, and secondary hypoxic axonal injury, respectively. Moreover, NSE was more sensitive procedure for detecting TAI than APP, because NSE immunostaining could detect axonal injuries in cases of head injury that survived more than 2 hours (APP ; more than 9 hours). Furthermore, IL-8 and TNF-α immunostaining could detect axonal injuries in cases of head injury that survived more than 3 days and 4 days, respectively. Our results suggested that immunostaining of proinflammatory cytokines such as IL-8 and TNF-α in the corpus callosum could be a new useful marker for estimating time interval after traumatic axonal injury.