Hyperbaric oxygen therapy mitigates respiratoryneuromuscular pathology after spinal cord injury

摘要 高压氧（HBO）治疗包括短暂（≤1小时）暴露于≤3 ATM的加压氧气， 经常用于伤口愈合和减压病。我们的初步数据和文献报告 中心假设，高压氧，在急性期（天至周）后，颈脊髓损伤 (SCI)，减轻横膈膜萎缩和功能障碍，减少颈脊髓病理，并改善 呼吸神经肌肉恢复HBO治疗与脑血管病的衰减之间的机制联系， SCI后的肌肉和神经病理学都是氧化应激。初步数据显示， 挫伤导致横膈膜中ROS的显著增加和萎缩。初步测试还 结果表明，10天1小时HBO治疗减少了膈肌ROS的形成，增加了膈肌ROS的生成， 抗氧化能力高压氧治疗也大大减轻了萎缩和收缩障碍 是在颈椎挫伤后发生的关于脊髓神经病理学，继发性损伤（即，病理 在最初的创伤后发展）损害运动恢复。初步组织学和分子数据 证明高压氧的神经保护作用，减少了颈部挫伤的继发性损伤， 脊髓这包括减弱的神经元损失，伴随凋亡标志物的表达减少， HBO治疗后的炎症。由于氧化应激有助于继发性损伤，我们预测HBO- 抗氧化剂表达的诱导上调是这些作用的基础。总的来说，保存下来的横膈膜 功能和减弱的宫颈病理导致我们的总体假设，呼吸恢复将是 通过HBO治疗得到改善。目的1将验证高压氧治疗在急性至亚急性期间 颈椎脊髓损伤后的早期阶段减少了横膈膜萎缩并改善了收缩力。假设将被检验 对膈肌进行组织学、分子和功能评估。为了测试氧化机制， 寡核苷酸将用于在HBO治疗期间阻断特异性抗氧化剂的翻译。以确定是否 抗氧化机制足以解释HBO的治疗效果，我们将过度表达特定的抗氧化机制。 使用腺相关病毒（AAV）的抗氧化剂。目标2将检验神经保护作用 在颈脊髓损伤后的急性期至亚急性期进行高压氧治疗可改善膈神经运动 复苏将用组织学、分子学和神经生理学方法（直接 膈神经记录和膈肌肌电图）。与目标1一样，机制研究将利用 反义寡核苷酸和AAV策略来调节脊髓中的抗氧化剂形成。共同主要研究者Dr. Smuder是横膈膜生物学和萎缩机制方面的专家。Co-PI Fuller博士拥有丰富的经验 在呼吸功能障碍的临床前SCI模型中。顾问迪恩博士是HBO的权威。

ABSTRACT Hyperbaric oxygen (HBO) therapy involves brief (≤1 hr) exposure to pressurized oxygen at ≤3 ATM and is used frequently for wound healing and decompression sickness. Our preliminary data and literature reports have led to the central hypothesis that HBO, delivered in the acute phases (days to weeks) after cervical spinal cord injury (SCI), attenuates diaphragm atrophy and dysfunction, reduces cervical spinal cord pathology, and improves respiratory neuromuscular recovery. The proposed mechanistic link between HBO therapy and attenuation of both muscular and neural pathology after SCI is oxidative stress. Preliminary data demonstrate that cervical contusion injury leads to substantial increases in ROS in the diaphragm and atrophy. Preliminary testing also showed that 1 hr HBO therapy for 10 days decreased diaphragm ROS formation and increased diaphragm antioxidant capacity. The HBO therapy also considerably attenuated the atrophy and contractile impairments that occurred after cervical contusion. In regards to spinal neuropathology, secondary damage (i.e., pathology that develops after the initial trauma) impairs motor recovery. Preliminary histological and molecular data demonstrate a neuroprotective impact of HBO with reduction in secondary damage in the contused cervical spinal cord. This includes attenuated neuronal loss with reduced expression of apoptotic markers and reduced inflammation after HBO therapy. Since oxidative stress contributes to secondary damage, we predict that HBO- induced upregulation of antioxidant expression underlies these effects. Collectively, the preserved diaphragm function and attenuated cervical pathology lead to our overall hypothesis that respiratory recovery will be improved by HBO therapy. Aim 1 will test the hypothesis that HBO therapy during acute through sub-acute phases after cervical SCI reduces diaphragm atrophy and improves contractility. The hypothesis will be tested with histological, molecular and functional evaluation of the diaphragm. To test oxidative mechanisms, antisense oligonucleotides will be used to block translation of specific antioxidants during HBO therapy. To determine if antioxidant mechanisms are sufficient to explain the HBO therapeutic effects, we will overexpress specific antioxidants using adeno-associated virus (AAV). Aim 2 will test the hypothesis that the neuroprotective impact of HBO therapy during acute through sub-acute phases after cervical SCI leads to improved phrenic motor recovery. The hypothesis will be tested with histological, molecular, and neurophysiological methods (direct phrenic nerve recordings and diaphragm electromyography). As in Aim 1, mechanistic studies will utilize antisense oligonucleotides and AAV strategies to modulate antioxidant formation in the spinal cord. Co-PI Dr. Smuder is an expert in diaphragm biology and mechanisms of atrophy. Co-PI Dr. Fuller has extensive experience in preclinical SCI models of respiratory dysfunction. Consultant Dr. Dean is an authority on HBO.