Anatomy and Neurobiology, 6889Virginia Commonwealth University, Richmond, Virginia, USA.
Pharmacology and Toxicology, 6889Virginia Commonwealth University, Richmond, Virginia, USA.
ASN Neuro. 2022 Jan-Dec;14:17590914221099112. doi: 10.1177/17590914221099112.
Traumatic brain injury (TBI) has consequences that last for years following injury. While TBI can precipitate a variety of diffuse pathologies, the mechanisms involved in injury-induced neuronal membrane disruption remain elusive. The lysosomal cysteine protease, Cathepsin B (Cath B), and specifically its redistribution into the cytosol has been implicated in cell death. Little is known about Cath B or neuronal membrane disruption chronically following diffuse TBI. Therefore, the current study evaluated Cath B and diffuse neuronal membrane disruption over a more chronic post-injury window (6 h-4 w). We evaluated Cath B in adult male Sprague-Dawley rats following central fluid percussion injury (CFPI). Expression of Cath B, as well as Cath B-associated pro (Bak and AIF) and anti-apoptotic (Bcl-xl) proteins, were assessed using western blot analysis. Cath B activity was also assessed. Localization of Cath B was evaluated in the membrane disrupted and non-disrupted population following CFPI using immunohistochemistry paired with quantitative image analysis and ultrastructural verification. There was no difference in expression or activity of Cath B or any of the associated proteins between sham and CFPI at any time post-injury. Immunohistological studies, however, showed a sub-cellular re-localization of Cath B at 2 w and 4 w post-injury in the membrane disrupted neuronal population as compared to the time-point matched non-disrupted neurons. Both membrane disruption and Cath B relocalization appear linked to neuronal atrophy. These observations are indicative of a late secondary pathology that represents an opportunity for therapeutic treatment of these neurons following diffuse TBI. Lysosomal cathepsin B relocalizes to the cytosol in neurons with disrupted plasmalemmal membranes weeks following diffuse brain injury. Both the membrane disrupted and cathepsin B relocalized neuronal subpopulations displayed smaller soma and nucleus size compared to non-pathological neurons, indicating atrophy.
创伤性脑损伤 (TBI) 在损伤后会持续多年产生后果。虽然 TBI 可能引发多种弥漫性病变，但涉及损伤诱导的神经元膜破坏的机制仍不清楚。溶酶体半胱氨酸蛋白酶 Cathepsin B (Cath B)，特别是其重新分布到细胞质中，与细胞死亡有关。关于 Cath B 或弥漫性 TBI 后慢性神经元膜破坏的了解甚少。因此，本研究在更慢性的损伤后窗口（6 h-4 w）评估了 Cath B 和弥漫性神经元膜破坏。我们评估了成年雄性 Sprague-Dawley 大鼠在中央液击伤（CFPI）后的 Cath B。使用 Western blot 分析评估 Cath B 以及 Cath B 相关的促凋亡（Bak 和 AIF）和抗凋亡（Bcl-xl）蛋白的表达。还评估了 Cath B 的活性。使用免疫组织化学结合定量图像分析和超微结构验证，评估 CFPI 后膜破坏和未破坏群体中 Cath B 的定位。在任何损伤后时间点，Cath B 或任何相关蛋白的表达或活性在假手术和 CFPI 之间均无差异。然而，免疫组织学研究显示，与时间匹配的未破坏神经元相比，在损伤后 2 w 和 4 w 的膜破坏神经元群体中，Cath B 出现亚细胞重新定位。膜破坏和 Cath B 重新定位似乎都与神经元萎缩有关。这些观察结果表明，这是一种迟发性二级病理，为弥漫性 TBI 后这些神经元的治疗提供了机会。溶酶体组织蛋白酶 B 在弥漫性脑损伤后数周内重新分布到有破裂质膜的神经元细胞质中。与非病变神经元相比，膜破坏和 Cath B 重新定位的神经元亚群的胞体和核体积均较小，表明萎缩。
