Integrated In Vivo and In Vitro Analysis of Alpha-Synuclein Aggregation and Neuroinflammatory Amplification in a Composite Parkinson's Disease Model.

This study aimed to investigate how α-synuclein (α-syn) is associated with microglial activation and inflammatory amplification in Parkinson's disease (PD), particularly under pro-inflammatory conditions. In vitro, BV2 microglial cells were stimulated with α-syn preformed fibrils (PFFs) and lipopolysaccharide (LPS). In vivo, a composite PD mouse model was established using 6-OHDA, LPS, and SNCA-overexpressing adeno-associated virus (AAV). Inflammatory changes were assessed by quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence. Midbrain transcriptomic profiles from model mice were analyzed using Affymetrix microarrays. Bioinformatic analyses included differential expression analysis with the limma package, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and Gene Set Enrichment Analysis (GSEA). Transcriptomic analysis showed coordinated upregulation and strong positive correlations (R > 0.73) among Snca, Tnfa, and Il1b in PD model mice. Enrichment analyses indicated prominent involvement of inflammation- and immune-related processes, including the JAK-STAT signaling pathway. In vitro, α-syn PFFs induced inflammatory responses in BV2 cells, and these responses were further enhanced by LPS co-stimulation. In vivo, the composite model showed increased α-syn aggregation, enhanced microglial activation, and elevated pro-inflammatory cytokine release under combined pathological conditions. Together, these findings indicate an amplified inflammatory response under combined pathological insults. Our findings suggest that α-syn aggregation is associated with enhanced microglial activation and inflammatory cytokine responses, and may exacerbate neuroinflammatory processes under inflammatory conditions in PD models.