Short-Chain Fatty Acid Aggregates Alpha-Synuclein Accumulation and Neuroinflammation via GPR43-NLRP3 Signaling Pathway in a Model Parkinson's Disease.

Parkinson's disease (PD) is characterized by the aggregation of α-synuclein (α-syn) and the loss of dopaminergic (DA) neurons, with growing evidence suggesting a significant role of gut microbiota and their metabolites in the disease's pathogenesis. This study explores the effects of short-chain fatty acids (SCFAs) on PD progression, focusing on the G protein-coupled receptor 43 (GPR43) and the NLRP3 signaling pathway in both in vitro and in vivo models. Employing the1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model and SH-SY5Y cells with SCFAs-treated, this study investigated the impact of SCFAs on α-syn deposition, DA loss, and neuroinflammation. In vitro, supernatant from STC-1 cells was administered to SH-SY5Y cells, and the effects were assessed following the knockdown of NLRP3 or GPR43. In vivo, mice were treated with NLRP3 or GPR43 inhibitors after feeding with SCFAs, and the motor deficits, α-syn pathology, DA neuronal loss, and inflammatory responses were observed. SCFAs were found to exacerbate motor and gastrointestinal dysfunctions in PD models, intensifying α-syn pathology and neuroinflammation. The activation of the NLRP3 inflammasome through GPR43 emerged as a key pathological mechanism, with inhibition of these molecules mitigating the observed effects. Such interventions reduced α-syn accumulation, DA loss, and inflammatory responses, highlighting the pivotal role of the SCFA/GPR43-NLRP3 pathway in PD. The findings from this study elucidate a critical link between gut-derived metabolic changes and neuroinflammatory processes in PD via the SCFA/GPR43-NLRP3 pathway. Targeting this pathway offers a promising therapeutic strategy and enriches our understanding of the gut-brain axis' role in PD progression.