An autonomous siRNA delivery system targeting NLRP3: implications in Parkinson's disease.

BACKGROUND: Parkinson's disease is the second most common neurodegenerative disease worldwide, with no disease-modifying therapy available. NLRP3 inflammasome-linked neuroinflammation is involved in the onset and progression of Parkinson's disease; therefore, inhibition of the NLRP3 inflammasome may provide a new gene therapy option. METHODS: In the present study, we developed a CMV-RVG-9dR-siR(NLRP3) construct that can be intravenously injected, self-assemble NLRP3-targeted small interfering RNA into extracellular vesicles in host liver cells, and functionally delivered to the brain to knock down NLRP3. The therapeutic effect of the synthetic construct was tested in two male mouse models of Parkinson's disease through biochemical and behavioral assays. RESULTS: Compared with the original RVG guide peptide, the modified RVG-9dR in the synthetic construct delivered higher levels of NLRP3-siRNA to the deep brain structures (substantia nigra and striatum). Injection of this modified synthetic construct attenuated MPTP- and α-synuclein-induced NLRP3 inflammasome activation, microgliosis, dopaminergic neurodegeneration, and motor impairments in the animal models for Parkinson's disease. CONCLUSIONS: Our study describes a modified synthetic construct that could improve the efficacy of siRNA delivery to deep brain structures and presents proof-of-principle evidence showing that genetic knockdown of NLRP3 could represent a new therapeutic strategy to treat Parkinson's disease and other neuroinflammation-related brain disorders.