A new biomarker for frontotemporal lobar degeneration with TDP-43 proteinopathy and Alzheimer's disease

总结 TDP-43（TAR DNA结合蛋白43 kDa）蛋白质病对公共卫生的影响估计为 与阿尔茨海默病（AD）的数量级相同。TDP-43首次与 额颞叶变性（FTLD）是65岁以下患者痴呆的第二大常见原因。 TDP-43后来被证明存在于高达60%的AD患者的大脑中，AD是痴呆症最常见的原因。 TDP-43病理在FTLD-TDP中是异质性的，并且与多发性痴呆综合征相关， 使活体患者的FTLD-TDP诊断复杂化。这些患者存在广泛的相关性， 由于其复杂的临床病理异质性导致不确定性， 围绕诊断。在阐明痴呆症的临床病理关系的一个主要障碍 FTLD-TDP的证候和特异性标志物是TDP-43包涵体的异质分子种类。 更具体地说，一些TDP-43种类是病理性的，而一些不是。类似地，AD中的TDP-43病理学 AD TDP类型与TDP-43和TDP-43的不同分子种类之间的关系是异质性的， 神经变性是未知的。因此，产生特异于病理性TDP-43种类的抗体 对于阐明FTLD-TDP和AD的临床病理关系至关重要。在筛选了5000多名 单克隆抗体（MAb）克隆在我们的实验室，我们已经成功地产生了新的，自制的MAb #9， 其特异于病理性TDP-43种类。该抗体可以强烈识别35 kDa的TDP-43 在人类中很少报道的物种，可以揭示大脑区域中额外的致密TDP-43包涵体， 神经变性本研究的目的是阐明这种新的MAb#9识别的病理性TDP-43 种及其与TDP-43病理学和FTLD-TDP和AD中的神经变性的关联。我们 假设MAb#9结合存在于独特内含物中的先前未描述的TDP-43种类， 局限于局部神经退化的大脑区域。我们将通过三个目标来检验这个假设。目标1： 将使用串联质谱技术阐明这种新的MAb#9检测的TDP-43种类的氨基酸序列 基于光谱的蛋白质组学分析。在目标2和3中，我们将确定MAb #9-MAb #10之间的关系。 FTLD-TDP和AD中的阳性包涵体、病理类型和局部神经变性， 免疫组织化学和神经病理学方法。这项研究的结果将大大提高我们的 了解一种新的毒性TDP-43种类及其与病理学和神经变性的关系。的 这一发现将是开发生物标志物的关键一步，该生物标志物可以预测活体FTLD中TDP-43的存在。 AD患者。鉴于TDP-43是治疗FTLD和现在的AD的潜在治疗靶点， 也可能对这两种疾病的未来疗法产生重大影响。

Summary The public health impact of TDP-43 (TAR DNA binding protein of 43 kDa) proteinopathy is estimated to be on the same order of magnitude as that of Alzheimer’s disease (AD). TDP-43 was first associated with frontotemporal lobar degeneration (FTLD), the second most common cause of dementia in patients under 65. TDP-43 was later shown to be present in up to 60% of brains with AD, the most common cause of dementia. TDP-43 pathology is heterogeneous in FTLD-TDP and is associated with multiple dementia syndromes, which complicates FTLD-TDP diagnosis in living patients. These patients, who present with a wide range of associated clinical symptoms, are underserved, as their complex clinicopathologic heterogeneity leads to uncertainty surrounding their diagnosis. A major hurdle in elucidating the clinicopathologic relationships between dementia syndromes and specific markers of FTLD-TDP is the heterogeneous molecular species of the TDP-43 inclusions. More specifically, some TDP-43 species are pathologic, while some are not. Similarly, TDP-43 pathology in AD is heterogeneous, and the AD TDP types’ associations with the different molecular species of TDP-43 and neurodegeneration are unknown. Thus, producing an antibody that is specific for the pathologic TDP-43 species will be crucial for elucidating the clinicopathologic relationship in FTLD-TDP and AD. After screening over 5,000 monoclonal antibody (MAb) clones in our lab, we have successfully produced the novel, home-made MAb #9, which is specific for the pathologic TDP-43 species. This antibody can strongly recognize a 35 kDa TDP-43 species rarely reported in humans and can reveal additional dense TDP-43 inclusions in brain areas showing neurodegeneration. The goals of this study are to elucidate this novel, MAb #9-recognized pathologic TDP-43 species and its association with TDP-43 pathology and neurodegeneration in FTLD-TDP and AD. We hypothesize that MAb #9 binds the previously undescribed TDP-43 species present in unique inclusions that localize to brain regions with local neurodegeneration. We will test this hypothesis via three aims. In Aim 1, we will elucidate the amino acid sequence of this novel MAb#9-detected TDP-43 species using tandem mass spectrometry-based proteomic analysis. In Aims 2 and 3, we will determine the relationships between MAb #9- positive inclusions, pathology types, and local neurodegeneration in FTLD-TDP and AD using immunohistochemical and neuropathological approaches. Findings from this study will significantly improve our understanding of a novel toxic TDP-43 species and its association with pathology and neurodegeneration. The findings will be a key step toward developing a biomarker that can predict the presence of TDP-43 in living FTLD and AD patients. Given that TDP-43 is a potential therapeutic target in treating FTLD and now AD, the knowledge will likely also have a significant impact on future therapies for both diseases.