rAAV2/7 vector-mediated overexpression of alpha-synuclein in mouse substantia nigra induces protein aggregation and progressive dose-dependent neurodegeneration

Background Alpha-synuclein is a key protein implicated in the pathogenesis of Parkinson's disease (PD). It is the main component of the Lewy bodies, a cardinal neuropathological feature in the disease. In addition, whole locus multiplications and point mutations in the gene coding for alpha-synuclein lead to autosomal dominant monogenic PD. Over the past decade, research on PD has impelled the development of new animal models based on alpha-synuclein. In this context, transgenic mouse lines have failed to reproduce several hallmarks of PD, especially the strong and progressive dopaminergic neurodegeneration over time that occurs in the patients. In contrast, viral vector-based models in rats and non-human primates display prominent, although highly variable, nigral dopaminergic neuron loss. However, the few studies available on viral vector-mediated overexpression of alpha-synuclein in mice report a weak neurodegenerative process and no clear Lewy body-like pathology. To address this issue, we performed a comprehensive comparative study of alpha-synuclein overexpression by means of recombinant adeno-associated viral vectors serotype 2/7 (rAAV2/7) at different doses in adult mouse substantia nigra. Results We noted a significant and dose-dependent alpha-synucleinopathy over time upon nigral viral vector-mediated alpha-synuclein overexpression. We obtained a strong, progressive and dose-dependent loss of dopaminergic neurons in the substantia nigra, reaching a maximum of 82% after 8 weeks. This effect correlated with a reduction in tyrosine hydroxylase immunoreactivity in the striatum. Moreover, behavioural analysis revealed significant motor impairments from 12 weeks after injection on. In addition, we detected the presence of alpha-synuclein-positive aggregates in the remaining surviving neurons. When comparing wild-type to mutant A53T alpha-synuclein at the same vector dose, both induced a similar degree of cell death. These data were supported by a biochemical analysis that showed a net increase in soluble and insoluble alpha-synuclein expression over time to the same extent for both alpha-synuclein variants. Conclusions In conclusion, our in vivo data provide evidence that strong and significant alpha-synuclein-induced neuropathology and progressive dopaminergic neurodegeneration can be achieved in mouse brain by means of rAAV2/7

Peripheral Inflammation Regulates CNS Immune Surveillance Through the Recruitment of Inflammatory Monocytes Upon Systemic α-Synuclein Administration

Innate immune activation and chronic neuroinflammation are characteristic features of many neurodegenerative diseases including Parkinson's disease (PD) and may contribute to the pathophysiology of the disease. The discovery of misfolded alpha-synuclein (αSYN) protein aggregates, which amplify in a “prion-like” fashion, has led us to consider that pathogenic αSYN might be hijacking the activation and mobilization mechanism of the peripheral immune system to reach and disseminate within the CNS. Furthermore, our lab and other groups have recently shown that αSYN can adopt distinct fibril conformations or “strains” with varying levels of pathogenic impact. Therefore, the aim of this study was to assess the impact of peripheral inflammation on αSYN spreading in order to better understand the participation of the immune system in the progression of PD. The results presented here show that intraperitoneal LPS injection prior to systemic intravenous recombinant administration of two different αSYN pathogenic strains (fibrils or ribbons) in wild type mice, induces an increase in brain resident microglia and promotes the recruitment of leukocytes toward the brain and the spinal cord. Our findings show for the first time that αSYN can be internalized by LPS-primed inflammatory monocytes, which in turn favors the dissemination from the periphery toward the brain and spinal cord. Further, we found a differential recruitment of CD4+ and CD8+ T cells after LPS priming and subsequent administration of the αSYN ribbons strain. Together, these data argue for a role of the peripheral immune system in αSYN pathology

Amnesic Syndrome in a Mammillothalamic Tract Infarction

It is controversial whether isolated lesions of mammillothalamic tract (MTT) produce significant amnesia. Since the MTT is small and adjacent to several important structures for memory, amnesia associated with isolated MTT infarction has been rarely reported. We report a patient who developed amnesia following an infarction of the left MTT that spared adjacent memory-related structures including the anterior thalamic nucleus. The patient's memory deficit was characterized by a severe anterograde encoding deficit and retrograde amnesia with a temporal gradient. In contrast, he did not show either frontal executive dysfunction or personality change that is frequently recognized in the anterior or medial thalamic lesion. We postulate that an amnesic syndrome can develop following discrete lesions of the MTT

The spectra of WC9 stars: evolution and dust formation

We present analyses of new optical spectra of three WC9 stars, WR 88, WR 92 and WR 103 to test the suggestion that they exemplify an evolutionary sequence amongst the WC9 stars. The spectrum of WR 88 shows conspicuous lines of N III and N IV, leading to classification as a transitional WN8o/WC9 star. The three stars show a sequence of increasing O II and O III line strengths, confirming and extending earlier studies. The spectra were analysed using CMFGEN models, finding greater abundances of oxygen and carbon in WR 103 than in WR 92 and, especially, in WR 88. Of the three stars, only WR 103 makes circumstellar dust. We suggest that oxygen itself does not enhance this process but that it is its higher carbon abundance that allows WR 103 to make dust

Low probability of disease cure in advanced ovarian carcinomas before the PARP inhibitor era

BACKGROUND: In ovarian carcinomas, the likelihood of disease cure following first-line medical-surgical treatment has been poorly addressed. The objective was to: (a) assess the likelihood of long-term disease-free (LDF) > 5 years; and (b) evaluate the impact of the tumour primary chemosensitivity (assessed with the modelled CA-125 KELIM) with respect to disease stage, and completeness of debulking surgery. METHODS: Three Phase III trial datasets (AGO-OVAR 9; AGO-OVAR 7; ICON-7) were retrospectively investigated in an "adjuvant dataset", whilst the Netherlands Cancer Registry was used in a "neoadjuvant dataset". The prognostic values of KELIM, disease stage and surgery outcomes regarding the likelihood of LDF were assessed using univariate/multivariate analyses. RESULTS: Of 2029 patients in the "adjuvant dataset", 82 (4.0%) experienced LDF (Stage I-II: 25.9%; III: 2.1%; IV: 0.5%). Multivariate analyses identified disease stage and KELIM (OR = 4.24) as independent prognostic factors. Among the 1452 patients from the "neoadjuvant dataset", 36 (2.4%) had LDF (Stage II-III: 3.3%; IV: 1.3%). Using multivariate tests, high-risk diseases (OR = 0.18) and KELIM (OR = 2.96) were significant. CONCLUSION: The probability of LDF > 5 years after first-line treatment in 3486 patients (<4%) was lower than thought. These data could represent a reference for future studies meant to assess progress related to PARP inhibitors

Leucine-rich repeat kinase 2 interacts with p21-activated kinase 6 to control neurite complexity in mammalian brain

Leucine-rich repeat kinase 2 (LRRK2) is a causative gene for Parkinson's disease, but the physiological function and the mechanism(s) by which the cellular activity of LRRK2 is regulated are poorly understood. Here, we identified p21-activated kinase 6 (PAK6) as a novel interactor of the GTPase/ROC domain of LRRK2. p21-activated kinases are serine-threonine kinases that serve as targets for the small GTP binding proteins Cdc42 and Rac1 and have been implicated in different morphogenetic processes through remodeling of the actin cytoskeleton such as synapse formation and neuritogenesis. Using an in vivo neuromorphology assay, we show that PAK6 is a positive regulator of neurite outgrowth and that LRRK2 is required for this function. Analyses of post-mortem brain tissue from idiopathic and LRRK2 G2019S carriers reveal an increase in PAK6 activation state, whereas knock-out LRRK2 mice display reduced PAK6 activation and phosphorylation of PAK6 substrates. Taken together, these results support a critical role of LRRK2 GTPase domain in cytoskeletal dynamics in vivo through the novel interactor PAK6, and provide a valuable platform to unravel the mechanism underlying LRRK2-mediated pathophysiology. We propose p21-activated kinase 6 (PAK6) as a novel interactor of leucine-rich repeat kinase 2 (LRRK2), a kinase involved in Parkinson's disease (PD). In health, PAK6 regulates neurite complexity in the brain and LRRK2 is required for its function, (a) whereas PAK6 is aberrantly activated in LRRK2-linked PD brain (b) suggesting that LRRK2 toxicity is mediated by PAK6

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Identification of the allosteric P2X7 receptor antagonist [11C]SMW139 as a PET tracer of microglial activation

The P2X7 receptor plays a significant role in microglial activation, and as a potential drug target, the P2X7 receptor is also an interesting target in positron emission tomography. The current study aimed at the development and evaluation of a potent tracer targeting the P2X7 receptor, to which end four adamantanyl benzamide analogues with high affinity for the human P2X7 receptor were labelled with carbon-11. All four analogues could be obtained in excellent radiochemical yield and high radiochemical purity and molar activity, and all analogues entered the rat brain. [11C]SMW139 showed the highest metabolic stability in rat plasma, and showed high binding to the hP2X7 receptor in vivo in a hP2X7 receptor overexpressing rat model. Although no significant difference in binding of [11C]SMW139 was observed between post mortem brain tissue of Alzheimer's disease patients and that of healthy controls in in vitro autoradiography experiments, [11C]SMW139 could be a promising tracer for P2X7 receptor imaging using positron emission tomography, due to high receptor binding in vivo in the hP2X7 receptor overexpressing rat model. However, further investigation of both P2X7 receptor expression and binding of [11C]SMW139 in other neurological diseases involving microglial activation is warranted