Parkinson's disease (PD) pathogenesis remains incompletely understood, with the causal link between gut microbiota dysbiosis and central neurodegeneration unclarified. This study aimed to unravel this complex interplay by integrating Mendelian randomization (MR) analysis, animal models, cellular experiments, and transcriptomic profiling. MR analysis identified Clostridium sensu stricto 1 and Candidatus Soleaferrea as novel genetic risk factors for PD, providing causal evidence for gut microbiota-driven PD pathogenesis. Using a chronic MPTP-induced PD mouse model, we confirmed that gut microbiota dysbiosis is accompanied by elevated tumor necrosis factor-α (TNF-α) in the intestine, plasma, and midbrain, along with dopaminergic neuron loss and motor deficits. Fecal microbiota transplantation (FMT) from healthy mice reversed these phenotypes, restoring gut homeostasis, reducing TNF-α levels, and preserving dopaminergic neurons. Transcriptomic analysis of mouse midbrain and human PD substantia nigra (GEO datasets) revealed ferroptosis as a key enriched pathway, with activating transcription factor 4 (ATF4) significantly upregulated in both PD models and patients. Mechanistically, TNF-α induced ATF4 overexpression in a concentration- and time-dependent manner, triggering dopaminergic neuron ferroptosis. This effect was mediated by TNF-α binding to TNFR1 (not TNFR2), activating the NF-κB pathway, and subsequently upregulating ATF4. Knockdown of ATF4 or inhibition of NF-κB reversed TNF-α-induced ferroptosis, as evidenced by restored glutathione (GSH) levels, reduced malondialdehyde (MDA) accumulation, and improved cell viability. Our findings establish a novel gut-brain axis-mediated pathogenic pathway: gut microbiota dysbiosis drives TNF-α-TNFR1-NF-κB-ATF4 signaling, leading to dopaminergic neuron ferroptosis and PD progression. This study bridges the gap between peripheral microbial dysbiosis and central neurodegeneration, identifies potential therapeutic targets, and highlights FMT as a promising intervention for PD.
