A novel enzymatic mechanism for removing neurotoxic aldehydes after rodent spinal cord injury

摘要 氧化应激在脊髓损伤(SCI)后功能丧失和脂质损伤中起关键致病作用 过氧化衍生的醛已成为造成这种继发性损伤的主要罪魁祸首。 对病理结果有显著影响。丙烯醛是活性最强的醛，对 降低丙烯醛可以显著缓解脊髓损伤时升高的神经元和脊髓损伤后的神经功能障碍。 因此，降低丙烯醛已成为治疗脊髓损伤的一种新的有效的治疗策略。线粒体 乙醛脱氢酶-2(ALDH2)是一种重要的氧化还原酶，具有很强的内源性抗醛作用 机械，清除人类和啮齿动物体内的有毒醛。强有力的证据表明，ALDH2很可能 对于保护神经元免受醛的伤害很重要，特别是在醛上调的情况下，如 SCI。然而，ALDH2在脊髓损伤发病机制中的作用从未被研究过。此外，虽然有能力 在代谢醛中，ALDH2可通过蛋白-醛加合物被醛损伤， 抑制ALDH2活性并导致随后的乙醛超载，这可能是脊髓损伤的一种情况。因此， 解除ALDH2的抑制和增强活性是一个合乎逻辑的解决方案，也可能是一种有效的策略 抑制脊髓损伤中的氧化应激和相关病理。使用一组新获得的转基因小鼠 (ALDH2*2)和新近发现的ALDH2激活剂(ALDA-1)，我们计划验证除醛和 ALDH2在脊髓损伤小鼠模型中的神经保护作用中心假说是ALDH2被抑制 在脊髓损伤后，在基因无效的ALDH2转基因小鼠中病情恶化。此外，ALDH2 ALDA-1的激活可恢复和增强其解醛功能，对脊髓损伤起到神经保护作用。 作为一个整体，我们发现脊髓损伤后丙烯醛增加，产生ALDH2*2小鼠，发现ALDA-1 AS ALDH2和ALDH2*2的选择性激活剂，并获得了ALDA-1可以降低丙烯醛的初步数据 受伤后增加。因此，我们为实现以下目标做好了充分准备：目标1.将ALDH2 活性与丙烯醛水平(指示氧化应激)、炎症以及相关的细胞和 脊髓损伤的行为病理学；目的2.确定抑制ALDH2是否能导致丙烯醛升高和 脊髓损伤后野生型和转基因小鼠(ALDH2*2)下游病变的加重；目标3。 确定催化激活剂ALDA-1增强ALDH2活性是否能抑制脊髓损伤后丙烯醛的升高 并在WT和ALDH2*2小鼠中提供神经保护。这些努力不仅将巩固关键作用 ALDH2在乙醛解毒中的作用，但也证明了增强ALDH2在脊髓损伤中的神经保护价值 作为一种潜在的治疗药物干预。预计这项研究的结果将大大扩大 并加强抗醛策略，以对抗脊髓损伤后的神经退行性变，并可能带来治疗 数以百万计的SCI受害者。

Abstract Oxidative stress plays a critical pathogenic role in functional loss after spinal cord injury (SCI), and lipid peroxidation-derived aldehydes have emerged as key culprits in sustaining such secondary injury, and contributing significantly to the pathological outcomes. Acrolein, the most reactive aldehyde, is highly toxic to neurons, elevated in SCI, and post-SCI neurological deficits can be significantly alleviated by lowering acrolein. As such, reducing acrolein has emerged as a novel and effective therapeutic strategy in SCI. Mitochondrial aldehyde dehydrogenase-2 (ALDH2) is a key oxidoreductase and powerful endogenous anti-aldehyde machinery, clearing toxic aldehydes in both humans and rodents. Strong evidence suggests that ALDH2 is likely important for protecting neurons from aldehydes, especially during situations of aldehyde upregulation such as SCI. However, the role of ALDH2 in SCI pathogenesis has never been investigated. Furthermore, while capable of metabolizing aldehydes, ALDH2 could be damaged by aldehydes through protein-aldehyde adducts, suppressing ALDH2 activity and leading to subsequent aldehyde overload, a likely scenario in SCI. As such, relieving the inhibition and boosting activity of ALDH2 is a logical solution, and likely an effective strategy to curtail oxidative stress and related pathologies in SCI. Using a combination of newly acquired transgenic mice (ALDH2*2) and recently-discovered ALDH2 activator (Alda-1), we plan to validate the aldehyde-clearing and neuroprotective role of ALDH2 in a mouse model of SCI. The central hypothesis is that ALDH2 is suppressed after SCI which is worsened in transgenic mice with genetically ineffective ALDH2. Furthermore, ALDH2 activation by Alda-1 can restore and boost its aldehyde-detoxification function providing neuroprotection in SCI. As a group, we have discovered acrolein increases after SCI, generated ALDH2*2 mice, discovered Alda-1 as a selective activator of ALDH2 and ALDH2*2, and obtained preliminary data that Alda-1 can mitigate acrolein increases after injury. Thus, we are well prepared to realize the following Aims: Aim 1. To correlate ALDH2 activity with the level of acrolein (indicative of oxidative stress), inflammation, and relevant cellular and behavioral pathologies in SCI; Aim 2. To determine if ALDH2 inhibition could lead to acrolein elevation and aggravation of downstream pathologies in wild type and transgenic mice (ALDH2*2) after SCI; Aim 3. To ascertain if ALDH2 activity enhancement by the catalytic activator Alda-1 could suppress post-SCI acrolein hike and provide neuroprotection in both WT and ALDH2*2 mice. These efforts will not only solidify the critical role of ALDH2 in aldehyde detoxification, but also demonstrate the neuroprotective value of boosting ALDH2 in SCI as a potential therapeutic drug intervention. It is expected that the outcome of this study will significantly broaden and enhance anti-aldehyde strategies in combating post-SCI neurodegeneration and potentially bring treatment to millions of SCI victims.