Ayers Jacob I, Brooks Mieu M, Rutherford Nicola J, Howard Jasie K, Sorrentino Zachary A, Riffe Cara J, Giasson Benoit I
Department of Neuroscience, University of Florida, Gainesville, Florida, USA
Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, USA.
J Virol. 2017 Jan 3;91(2). doi: 10.1128/JVI.02095-16. Print 2017 Jan 15.
Misfolded α-synuclein (αS) is hypothesized to spread throughout the central nervous system (CNS) by neuronal connectivity leading to widespread pathology. Increasing evidence indicates that it also has the potential to invade the CNS via peripheral nerves in a prion-like manner. On the basis of the effectiveness following peripheral routes of prion administration, we extend our previous studies of CNS neuroinvasion in M83 αS transgenic mice following hind limb muscle (intramuscular [i.m.]) injection of αS fibrils by comparing various peripheral sites of inoculations with different αS protein preparations. Following intravenous injection in the tail veins of homozygous M83 transgenic (M83) mice, robust αS pathology was observed in the CNS without the development of motor impairments within the time frame examined. Intraperitoneal (i.p.) injections of αS fibrils in hemizygous M83 transgenic (M83) mice resulted in CNS αS pathology associated with paralysis. Interestingly, injection with soluble, nonaggregated αS resulted in paralysis and pathology in only a subset of mice, whereas soluble Δ71-82 αS, human βS, and keyhole limpet hemocyanin (KLH) control proteins induced no symptoms or pathology. Intraperitoneal injection of αS fibrils also induced CNS αS pathology in another αS transgenic mouse line (M20), albeit less robustly in these mice. In comparison, i.m. injection of αS fibrils was more efficient in inducing CNS αS pathology in M83 mice than i.p. or tail vein injections. Furthermore, i.m. injection of soluble, nonaggregated αS in M83 mice also induced paralysis and CNS αS pathology, although less efficiently. These results further demonstrate the prion-like characteristics of αS and reveal its efficiency to invade the CNS via multiple routes of peripheral administration.
The misfolding and accumulation of α-synuclein (αS) inclusions are found in a number of neurodegenerative disorders and is a hallmark feature of Parkinson's disease (PD) and PD-related diseases. Similar characteristics have been observed between the infectious prion protein and αS, including its ability to spread from the peripheral nervous system and along neuroanatomical tracts within the central nervous system. In this study, we extend our previous results and investigate the efficiency of intravenous (i.v.), intraperitoneal (i.p.), and intramuscular (i.m.) routes of injection of αS fibrils and other protein controls. Our data reveal that injection of αS fibrils via these peripheral routes in αS-overexpressing mice are capable of inducing a robust αS pathology and in some cases cause paralysis. Furthermore, soluble, nonaggregated αS also induced αS pathology, albeit with much less efficiency. These findings further support and extend the idea of αS neuroinvasion from peripheral exposures.
错误折叠的α-突触核蛋白（αS）被认为通过神经元连接在中枢神经系统（CNS）中传播，导致广泛的病理变化。越来越多的证据表明，它也有可能以朊病毒样的方式通过外周神经侵入中枢神经系统。基于朊病毒经外周途径给药后的有效性，我们扩展了之前对M83 αS转基因小鼠后肢肌肉（肌内[i.m.]）注射αS原纤维后中枢神经系统神经侵袭的研究，通过比较不同αS蛋白制剂在不同外周接种部位的情况。在纯合M83转基因（M83）小鼠的尾静脉进行静脉注射后，在中枢神经系统中观察到强烈的αS病理变化，在所检查的时间范围内未出现运动障碍。在半合子M83转基因（M83）小鼠中腹腔内（i.p.）注射αS原纤维导致与麻痹相关的中枢神经系统αS病理变化。有趣的是，注射可溶性、非聚集的αS仅在一部分小鼠中导致麻痹和病理变化，而可溶性Δ71 - 82 αS、人βS和钥孔血蓝蛋白（KLH）对照蛋白未诱导任何症状或病理变化。腹腔内注射αS原纤维在另一种αS转基因小鼠品系（M20）中也诱导了中枢神经系统αS病理变化，尽管在这些小鼠中不太明显。相比之下，在M83小鼠中，肌内注射αS原纤维比腹腔内或尾静脉注射更有效地诱导中枢神经系统αS病理变化。此外，在M83小鼠中肌内注射可溶性、非聚集的αS也诱导了麻痹和中枢神经系统αS病理变化，尽管效率较低。这些结果进一步证明了αS的朊病毒样特征，并揭示了其通过多种外周给药途径侵入中枢神经系统的效率。
α-突触核蛋白（αS）包涵体的错误折叠和积累在多种神经退行性疾病中被发现，是帕金森病（PD）和PD相关疾病的标志性特征。在感染性朊病毒蛋白和αS之间观察到了类似的特征，包括其从外周神经系统扩散并沿着中枢神经系统内神经解剖通路传播的能力。在本研究中，我们扩展了之前的结果，研究了静脉内（i.v.）、腹腔内（i.p.）和肌内（i.m.）注射αS原纤维及其他蛋白对照的效率。我们的数据表明，在αS过表达小鼠中通过这些外周途径注射αS原纤维能够诱导强烈的αS病理变化，在某些情况下导致麻痹。此外，可溶性、非聚集的αS也诱导了αS病理变化，尽管效率要低得多。这些发现进一步支持并扩展了αS从外周暴露侵入神经的观点。
