The Small Molecule Alpha-Synuclein Aggregator, FN075, Enhances Alpha-Synuclein Pathology in Subclinical AAV Rat Models

Intra-striatal infusion of the small molecule alpha-synuclein aggregator, FN075, does not enhance parkinsonism in a subclinical AAV-alpha-synuclein rat model

Numerous challenges hinder the development of neuroprotective treatments for Parkinson's disease, with a regularly identified issue being the lack of clinically relevant animal models. Viral vector overexpression of α-synuclein is widely considered the most relevant model; however, this has been limited by high variability and inconsistency. One potential method of optimisation is pairing it with a secondary insult such as FN075, a synthetic molecule demonstrated to accelerate α-synucleinopathy. Thus, the aim of this study was to investigate if sequential infusion of adeno-associated virus (AAV)-α-synuclein and FN075 into the rat brain can replicate α-synucleinopathy, nigrostriatal pathology and motor dysfunction associated with Parkinson's disease. Rats received a unilateral injection of AAV-α-synuclein (or AAV-green fluorescent protein) into two sites in the substantia nigra, followed 4 weeks later by unilateral injection of FN075 (or vehicle) into the striatum. Animals underwent behavioural testing every 4 weeks until sacrifice at 20 weeks, followed by immunohistochemistry assessment post-mortem. As anticipated, AAV-α-synuclein led to extensive overexpression of human α-synuclein throughout the nigrostriatal pathway, as well as elevated levels of phosphorylated and aggregated forms of the protein. However, the sequential administration of FN075 into the striatum did not exacerbate any of the α-synuclein pathology. Furthermore, despite the extensive α-synuclein pathology, neither administration of AAV-α-synuclein nor FN075, alone or in combination, was sufficient to induce dopaminergic degeneration or motor deficits. In conclusion, this approach did not replicate the key characteristics of Parkinson's disease, and further studies are required to create more representational models for testing of novel compounds and treatments for Parkinson's disease.

Neuronanomedicine for Alzheimer's and Parkinson's disease: Current progress and a guide to improve clinical translation

Neuronanomedicine is an emerging multidisciplinary field that aims to create innovative nanotechnologies to treat major neurodegenerative disorders, such as Alzheimer's (AD) and Parkinson's disease (PD). A key component of neuronanomedicine are nanoparticles, which can improve drug properties and demonstrate enhanced safety and delivery across the blood-brain barrier, a major improvement on existing therapeutic approaches. In this review, we critically analyze the latest nanoparticle-based strategies to modify underlying disease pathology to slow or halt AD/PD progression. We find that a major roadblock for neuronanomedicine translation to date is a poor understanding of how nanoparticles interact with biological systems (i.e., bio-nano interactions), which is partly due to inconsistent reporting in published works. Accordingly, this review makes a set of specific recommendations to help guide researchers to harness the unique properties of nanoparticles and thus realise breakthrough treatments for AD/PD.

Time-Course of Alterations in the Endocannabinoid System after Viral-Mediated Overexpression of α-Synuclein in the Rat Brain

Since the discovery of α-synuclein as the major component in Lewy bodies, research into this protein in the context of Parkinson's disease pathology has been exponential. Cannabinoids are being investigated as potential therapies for Parkinson's disease from numerous aspects, but still little is known about the links between the cannabinoid system and the pathogenic α-synuclein protein; understanding these links will be necessary if cannabinoid therapies are to reach the clinic in the future. Therefore, the aim of this study was to investigate the time-course of alterations in components of the endocannabinoid system after viral-mediated α-synuclein overexpression in the rat brain. Rats were given unilateral intranigral injections of AAV-GFP or AAV-α-synuclein and sacrificed 4, 8 and 12 weeks later for qRT-PCR and liquid chromatography-mass spectrometry analyses of the endocannabinoid system, in addition to histological visualization of α-synuclein expression along the nigrostriatal pathway. As anticipated, intranigral delivery of AAV-α-synuclein induced widespread overexpression of human α-synuclein in the nigrostriatal pathway, both at the mRNA level and the protein level. However, despite this profound α-synuclein overexpression, we detected no differences in CB1 or CB2 receptor expression in the nigrostriatal pathway; however, interestingly, there was a reduction in the expression of neuroinflammatory markers. Furthermore, there was a reduction in the levels of the endocannabinoid 2-AG and the related lipid immune mediator OEA at week 12 post-surgery, indicating that α-synuclein overexpression triggers dysregulation of the endocannabinoid system. Although this research does show that the endocannabinoid system is impacted by α-synuclein, further research is necessary to more comprehensively understand the link between the cannabinoid system and the α-synuclein aspect of Parkinson's disease pathology in order for cannabinoid-based therapies to be feasible for the treatment of this disease in the coming years.