Acidic nanoparticles protect against α-synuclein-induced neurodegeneration through the restoration of lysosomal function

Parkinson's disease (PD) is an age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra, associated with the accumulation of misfolded α-synuclein and lysosomal impairment, two events deemed interconnected. Protein aggregation is linked to defects in degradation systems such as the autophagy-lysosomal pathway, while lysosomal dysfunction is partly related to compromised acidification. We have recently proven that acidic nanoparticles (aNPs) can re-acidify lysosomes and ameliorate neurotoxin-mediated dopaminergic neurodegeneration in mice. However, no lysosome-targeted approach has yet been tested in synucleinopathy models in vivo. Here, we show that aNPs increase α-synuclein degradation through enhancing lysosomal activity in vitro. We further demonstrate in vivo that aNPs protect nigral dopaminergic neurons from cell death, ameliorate α-synuclein pathology, and restore lysosomal function in mice injected with PD patient-derived Lewy body extracts carrying toxic α-synuclein aggregates. Our results support lysosomal re-acidification as a disease-modifying strategy for the treatment of PD and other age-related proteinopathies.