Detoxification of Biogenic Aldehydes in Parkinson's Disease

帕金森病(PD)是第二大最常见的年龄相关性神经退行性疾病，仅次于 阿尔茨海默氏症，影响65-85岁人口的5%。退伍军人患癌症的风险增加 PD是因为退伍军人人口比美国整体人口更老，也因为退伍军人 在部署过程中更有可能接触到有毒的环境制剂。尽管取得了长足的进步， 在过去二十年的研究中，该病的病因和发病机制在很大程度上仍不清楚。 尽管家系已被确认为单基因突变，但大多数帕金森病病例被归类为 特发性的。动物研究和随后的流行病学研究已经确定了 特发性或散发性帕金森病患者在环境中暴露于百草枯、甘露醇和鱼藤酮等药物。这个 暴露于不同作用机制的杀虫剂可能增加帕金森病风险的机制 还没有完全了解，预防或减缓疾病进展的治疗策略也没有得到 已确认身份。然而，来自我们实验室和其他实验室的越来越多的证据表明，乙醛受损 解毒。例如，在PD的SN中胞浆乙醛脱氢酶(ALDH1)的表达减少 病人。散发性帕金森病患者中枢和外周组织中ALDH1的广泛降低提示 将其用作诊断生物标志物的可能性。农村社区的流行病学研究 加利福尼亚州的中央山谷已经将线粒体乙醛脱氢酶(ALDH2)的多态与 接触农用杀虫剂的人患帕金森病的风险增加。 我们的工作假设是暴露在空气中导致的乙醛排毒功能受损 环境因素和/或乙醛脱氢酶表达减少会导致“醛”升高 负荷“包括增加3，4-二羟基苯乙醛(DOPAL)和4-羟基壬烯醛的水平 (4-HNE)，分别是多巴胺代谢和脂质过氧化的醛产物。我们 假设这些醛可能与α-突触核蛋白形成加合物，产生有毒的纤维，从而导致 神经退行性变。为了在体内验证这一假设，我们创建了一组携带纯合子突变的小鼠 仅有的两种乙醛脱氢酶同工酶Aldh1a1和ALDH2已知存在于中脑多巴胺中 神经元。Aldh1a1-/-xAldh2-/-(DKO)小鼠表现出DOPAL和4-HNE升高，先于年龄相关 运动功能受损，多巴胺和代谢物减少，以及中脑多巴胺神经元丢失 从12个月左右开始，持续发展到至少23个月。然后我们穿过了这个 高表达人野生型α-突触核蛋白小鼠至小鼠三重转基因系的建立 确定生物醛升高对α-突触核蛋白的下游影响。初步行为研究 显示生物醛的升高加速了步态、旋转棒等与年龄相关的指标的下降 TTG小鼠的运动能力、撑杆试验和精细运动能力。我们在下一个资金阶段的总体目标 是从力学上理解体内生物醛和α-突触核蛋白之间的联系 多巴胺能功能障碍。然后我们将评估醛作为FDA批准的治疗靶点 降低有毒醛水平以减缓或预防神经病理和行为的药物 帕金森病的临床表现。具体目标是：具体目标1：确定升高的生物成因 醛加剧了过度表达人类野生型αSYN的小鼠的行为缺陷。具体目标2： 确定升高的生物醛是否加剧了大鼠的神经化学和组织病理学变化 高表达人野生型α基因的小鼠。具体目标3：确定肼丙嗪，一种可以 捕获醛，将挽救在AIMS 1和2中观察到的行为和神经化学变化。 提议将可能确定新的治疗靶点和药物来治疗退伍军人 帕金森氏症。

Parkinson's disease (PD) is the second most prevalent age-related neurodegenerative disorder, after Alzheimer's disease, affecting up to 5% of the population aged 65 – 85 years. Veterans are at increased risk for PD because the veteran population is older than the United States population as a whole and because veterans are more likely to have been exposed to toxic environmental agents during deployment. Despite great strides in research over the past two decades, the etiology and pathogenesis of the disease is still largely unknown. Although families have been identified with single gene mutations, the majority of PD cases are classified as idiopathic. Animal studies, and subsequent epidemiological studies, have established a link between environmental exposure to agents such as paraquat, maneb and rotenone in idiopathic or sporadic PD. The mechanisms by which exposure to pesticides with different mechanisms of action may increase the risk of PD are not fully understood, and treatment strategies to prevent or slow disease progression have not been identified. However, a growing body of evidence from our lab and others has implicated impaired aldehyde detoxification. For example, cytosolic aldehyde dehydrogenase (ALDH1) expression is reduced in the SN of PD patients. The widespread reduction in ALDH1 in central and peripheral tissues in sporadic PD has suggested the possibility of using it as a diagnostic biomarker. Epidemiological studies of the farming communities in the Central Valley in California have linked polymorphisms in mitochondrial aldehyde dehydrogenase (ALDH2) to enhanced risk of PD in people exposed to agricultural pesticides. Our working hypothesis is that impaired aldehyde detoxification consequent to exposure to environmental agents, and/or reduced aldehyde dehydrogenase expression leads to elevated “aldehyde load” including increased levels of 3,4-dihydroxyphenylacetaldehyde (DOPAL) and 4-hydroxynonenal (4-HNE), aldehyde products of dopamine metabolism and lipid peroxidation, respectively. We hypothesize that these aldehydes may form adducts with α-synuclein producing toxic fibrils that cause neurodegeneration. To test this hypothesis in vivo, we created a line of mice with homozygous mutations in the only two aldehyde dehydrogenase isozymes, Aldh1a1 and Aldh2, known to be present in midbrain dopamine neurons. The Aldh1a1-/-xAldh2-/- (DKO) mice exhibit elevation of DOPAL and 4-HNE that precedes age-related impairments in motor function, reduced dopamine and metabolites, and loss of midbrain dopamine neurons starting around 12 months of age and continuing to progress to at least 23 months of age. We then crossed this line of mice to mice overexpressing human wild-type α-synuclein to create a triple transgenic line (TTG) to determine the downstream effects of elevated biogenic aldehydes on α-synuclein. Preliminary behavioral studies show that elevated biogenic aldehydes accelerate the age-related decline in measures of gait, rotarod performance, pole-test and fine motor performance in TTG mice. Our overall aim in the next period of funding is to understand mechanistically the link between biogenic aldehydes and α-synuclein in vivo in dopaminergic dysfunction. We will then evaluate aldehydes as therapeutic targets for FDA approved agents that reduce toxic aldehyde levels to slow or prevent the neuropathological and behavioral manifestations of PD. The Specific Aims are: Specific Aim 1: To determine whether elevated biogenic aldehydes exacerbates behavioral deficits in mice overexpressing human wildtype αSyn. Specific Aim 2: To determine whether elevated biogenic aldehydes exacerbate neurochemical and histopathological changes in mice overexpressing human wildtype αSyn. Specific Aim 3: To determine whether hydralazine, an agent that traps aldehydes, will rescue behavioral and neurochemical changes observed in Aims 1 and 2. The work proposed will potentially identify new therapeutic targets and agents for treatment of veterans with Parkinson's disease.