Treatment of Catecholaminergic Neurodegeneration

(A)遗传性帕金森病(PD)交感神经中的α-突触核蛋白(AS)沉积：PD导致交感去甲肾上腺素能神经在脑外积聚。在与Derek Narendra(神经遗传学分部)的合作中，我们比较了不同遗传形式的帕金森病神经元内AS沉积的大小。用皮肤活检组织中AS酪氨酸羟化酶(TH)共定位指数测定交感神经As沉积。SNCA、DJ-1、LRRK2和GBA突变与AS-TH共定位指数高相关，而PRKN突变与AS-TH共定位指数无关。在皮肤活检中计算AS-TH共定位指数可能有助于确定以AS为靶点的实验性治疗试验的最合适候选者(PMID 34076298)。 (B)验证儿茶醛假说的动物模型：我们与特拉维夫大学的合作者发现，给予杀虫剂鱼藤酮可以复制帕金森病患者中发现的异常脑神经化学模式，包括自毒的儿茶酚醛3，4-二羟基苯乙醛(DOPAL)的积聚。我们正在测试减少DOPAL的形成和氧化是否可以防止该模型中异常的神经化学模式和相关的神经行为异常(PMID 34842277)。 (C)预测LBDS治疗反应的计算建模：当患者出现LBD症状时，儿茶酚胺能神经元已经大量丧失。识别临床前LBD的生物标记物对于最大限度地发挥疾病修正治疗的效果可能至关重要。我们扩展了以前发表的一个计算模型，该模型包含了多巴胺代谢物DOPAL与AS的有害相互作用。模型显示儿茶酚胺含量的三阶段丢失，从第一阶段的动态平衡到第二阶段的动态平衡和快速的儿茶酚胺耗竭，以减缓症状第三阶段的进一步损失。该模型预测，在从动态平衡到动态平衡的转变过程中抑制DOPAL的产生应该会大大推迟症状性LBDS的发生。将计算模型与临床实验室生物标记物相结合来检测临床前疾病，可以为LBDS的实验性治疗试验提供关于疾病进展和针对特定神经元内功能障碍的个性化预测(PMID 35621196)。 (D)门克斯病的诊断和治疗：门克斯病是一种罕见的铜代谢障碍，通常在儿童时期是致命的。将多巴胺转化为去甲肾上腺素的酶含有铜，需要铜。我们正在与俄亥俄州立大学的研究人员合作，建立孟克斯病基因治疗的动物模型，以期在未来进行临床试验。我们还签订了一项关于使用去甲肾上腺素前体药物L-Thre-3，4-二羟基苯丝氨酸治疗孟克斯病患者的OH的合作研究和开发协议。我们继续通过CLIA认证的实验室，为有孟克斯病风险的新生儿提供血浆儿茶酚水平的诊断分析，作为一项公共服务。 (E)治疗认知功能障碍的托莫西汀抑制人脑中儿茶酚胺的再摄取：药物托莫西汀抑制从大脑和外周神经元释放的去甲肾上腺素的再摄取，目前正在对轻度认知功能障碍的患者进行测试。与埃默里的合作者一起，我们发现，托莫西汀治疗产生了一种脑脊液神经化学模式，与大脑中去甲肾上腺素和多巴胺的重新摄取减少一致(PMID 34919634)。 (F)硬膜外脊髓刺激治疗脊髓损伤患者的低血压(低血压)：与大学的研究人员合作。我们正在评估硬膜外脊髓刺激对脊髓损伤后OH患者血浆儿茶酚胺和相关化合物水平的影响。 (G)儿茶酚胺相关化合物的LC-MS/MS：采用液相色谱-电化学检测法对DOPAL和DOPEGAL进行生物化学分析在技术上受到限制。为了证明实验治疗措施对DOPAL和DOPEGAL水平的影响，串联和飞行时间质谱仪(LC-MS/MS)似乎更好。这种方法也可以用来识别人体血浆中与咖啡相关的儿茶酚。根据一项技术转让协议，我们正在探索商用LC-MS/MS系统是否有效地测量血浆DOPAL和DOPEGAL。

(A) Alpha-Synuclein (AS) deposition in sympathetic nerves in genetic Parkinson's disease (PD): PD entails AS buildup outside the brain in sympathetic noradrenergic nerves. In collaboration with Derek Narendra (Neurogenetics Branch) we compared magnitudes of intra-neuronal AS deposition across genetic forms of PD. AS deposition in sympathetic nerves was measured by the AS-tyrosine hydroxylase (TH) colocalization index in skin biopsies. SNCA, DJ-1, LRRK2, and GBA mutations were found to be associated with high AS-TH colocalization indexes, whereas PRKN mutations were not. Calculating AS-TH colocalization indexes in skin biopsies may be informative for identifying the most appropriate candidates for experimental therapeutic trials targeting AS (PMID 34076298). (B) Animal model to test the catecholaldehyde hypothesis: With collaborators at the Tel Aviv University we found that administration of the pesticide rotenone reproduces the abnormal brain neurochemical pattern found in PD, including buildup of the autotoxic catecholaldehyde 3,4-dihydroxyphenylacetaldehyde (DOPAL. We are testing whether decreasing DOPAL formation and oxidation prevents the abnormal neurochemical pattern and associated neurobehavioral abnormalities in this model (PMID 34842277). (C) Computational modeling to predict responses to treatment in LBDs: By the time a patient develops symptoms of a LBD, there is already substantial loss of catecholaminergic neurons. Identifying biomarkers of preclinical LBDs may be crucial for maximizing the effectiveness of disease-modifying treatments. We extended on a previously published computational model that incorporates harmful interactions of the dopamine metabolite DOPAL with AS. The modeling indicated tri-phasic loss of catecholamine contents, from homeostasis in the first phase to dyshomeostasis and rapid catecholamine depletion in the second phase to slow further loss in the symptomatic third phase. The model predicts that inhibiting DOPAL production at the transition from homeostasis to dyshomeostasis should substantially delay the onset of symptomatic LBDs. Combining computational modeling with clinical laboratory biomarkers to detect preclinical disease may enable individualized predictions about disease progression and target specific intra-neuronal dysfunctions for experimental therapeutic trials in LBDs (PMID 35621196). (D) Diagnosis and treatment of Menkes disease: Menkes disease is a rare disorder of copper metabolism that usually is lethal in childhood. The enzyme that converts dopamine to norepinephrine contains and requires copper. We are collaborating with investigators at the Ohio State University on animal models of gene therapy treatments for Menkes disease, with a view to a future clinical trial. We also have in place a Cooperative Research and Development Agreement regarding treating OH with the norepinephrine pro-drug L-thre-3,4-dihydroxyphenylserine in Menkes disease patients. We continue to offer as a public service diagnostic assays of plasma levels of catechols in newborns at risk of Menkes disease, via our CLIA-certified laboratory. (E) Atomoxetine to treat cognitive dysfunction inhibits catecholamine reuptake in the human brain: The drug atomoxetine inhibits the reuptake of norepinephrine released from neurons in the brain and periphery and is being tested in people with mild cognitive dysfunction. With collaborators at Emory we found that atomoxetine treatment produces a cerebrospinal fluid neurochemical pattern consistent with decreased reuptake of both norepinephrine and dopamine in the brain (PMID 34919634). (F) Epidural spinal cord stimulation for low blood pressure (hypotension) in patients with spinal cord injury: In collaboration with investigators at the Univ. of Louisville we are evaluating effects of epidural spinal cord stimulation on plasma levels of catecholamines and related compounds in people with OH after spinal cord injury. (G) LC-MS/MS for catecholamine-related compounds: Biochemical assays of DOPAL and DOPEGAL by liquid chromatography with electrochemical detection are limited technologically. To document effects of experimental therapeutic measures on DOPAL and DOPEGAL levels, liquid chromatography with tandem and time of flight mass spectrometry (LC-MS/MS) seems superior. This methodology could also be used to identify coffee-related catechols in human plasma. Under a technology transfer agreement we are exploring whether a commercially available LC-MS/MS system validly measures plasma DOPAL and DOPEGAL.