Neurological Disorder Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar.
Neural Plasticity and Repair Unit, Department of Experimental Medical Sciences, Wallenberg Neuroscience Center, Lund University, Lund, Sweden.
Neuropathol Appl Neurobiol. 2019 Oct;45(6):597-608. doi: 10.1111/nan.12531. Epub 2018 Dec 3.
Lewy body diseases are neuropathologically characterized by the abnormal accumulation of α-synuclein (α-syn) protein within vulnerable neurons. Although studies have evaluated α-syn in post mortem brain tissue, previous findings have been limited by typically employing pan-α-syn antibodies that may not recognize disease-relevant forms of protein. We investigated the presence of α-syn species present in post mortem brain tissues from Lewy body disease and Alzheimer's disease.
Soluble and insoluble/aggregated α-syn from frontal cortex of post mortem brain tissues form Parkinson's disease (PD), dementia with Lewy bodies (DLB), Alzheimer's disease (AD) and aged control cases were sequentially extracted using buffers with increasing detergent concentrations. Enzyme-linked immunosorbent assay (ELISA) was used to quantify the levels of total-, oligomeric- and phosphorylated-Ser129-α-syn (t-, o- and pS129-α-syn). ELISA data were validated by western blot and compared to histological data from the same region of the contralateral hemisphere.
There was no difference in t-α-syn levels between groups in the aqueous-soluble, detergent-soluble or urea-soluble tissue fractions. However, aqueous-soluble non-phosphorylated o-α-syn was increased not only in PD and DLB but also in AD without neocortical Lewy bodies. In PD and AD, pS129-α-syn was increased in the detergent-soluble tissue fragment and, in AD, this was positively correlated with the burden of tau pathology. Increased levels of urea-soluble pS129-α-syn were demonstrated only in DLB tissue lysates but this did not correlate with Lewy body pathological burden.
Taken together, these findings suggest that DLB have elevated levels of insoluble pS129-α-syn, but that increased levels of aqueous-soluble o-α-syn and detergent-soluble pS129-α-syn are also observed in PD and AD, suggesting different changes to α-syn across the spectrum of neurodegenerative proteopathies.
路易体病的神经病理学特征是脆弱神经元内异常积累α-突触核蛋白（α-syn）。虽然已有研究评估了尸检脑组织中的α-syn，但之前的发现受到限制，因为通常采用的泛α-syn 抗体可能无法识别与疾病相关的蛋白形式。我们研究了路易体病和阿尔茨海默病尸检脑组织中存在的α-syn 物种。
使用具有递增洗涤剂浓度的缓冲液，从帕金森病（PD）、路易体痴呆（DLB）、阿尔茨海默病（AD）和老年对照组的尸检大脑组织的额皮质中依次提取可溶的和不可溶/聚集的α-syn。酶联免疫吸附测定（ELISA）用于定量总-α-syn（t-α-syn）、寡聚体-α-syn（o-α-syn）和磷酸化-Ser129-α-syn（pS129-α-syn）的水平。ELISA 数据通过 Western blot 进行验证，并与对侧大脑半球同一区域的组织学数据进行比较。
在水可溶、去污剂可溶或尿素可溶组织部分，各组之间的 t-α-syn 水平没有差异。然而，不仅在 PD 和 DLB，而且在无皮质路易体的 AD 中，水相非磷酸化的 o-α-syn 增加。在 PD 和 AD 中，pS129-α-syn 在去污剂可溶组织片段中增加，并且在 AD 中，与 tau 病理学负担呈正相关。仅在 DLB 组织裂解物中观察到增加的尿素可溶性 pS129-α-syn 水平，但与路易体病理负担无关。
综上所述，这些发现表明 DLB 具有升高的不溶性 pS129-α-syn 水平，但 PD 和 AD 中也观察到升高的水相可溶性 o-α-syn 和去污剂可溶性 pS129-α-syn 水平，提示在神经退行性变的蛋白病谱中α-syn 发生不同变化。
