Spike RBD drives sustained Parkinson's disease progression via microglia-neuron crosstalk-mediated RTP801 upregulation.

Abstract

INTRODUCTION: Emerging evidence highlights the exacerbation and sustained Parkinson's disease (PD) progression following COVID-19. The SARS-CoV-2 spike receptor-binding domain (RBD), which can persist in the brain post-infection, is a likely contributor, but how it drives this neuropathology is unclear. OBJECTIVES: To elucidate the underlying mechanisms of long COVID's impact on PD and identify mechanism that contribute to the continuous progression of PD. METHODS: The SARS-CoV-2 spike RBD was stereotactically injected into the substantia nigra pars compacta of α-synuclein (αSyn) A53T mice within a chronic stress-genetic susceptibility model. We characterized the pathological impact of RBD using motor and non-motor behavioral tests, fMRI-based functional connectivity, in vivo electrophysiology, immunofluorescence, and αSyn aggregate analysis. To elucidate the underlying mechanisms, we then employed RNA-sequencing, transmission electron microscopy, microglial depletion, and comparative studies in αSyn A53T mice lacking RTP801 (αSyn A53T; RTP801). RESULTS: RBD accelerated PD-related motor and non-motor symptom deterioration, impaired brain functional connectivity, and reduced neuronal excitability. It exacerbated dopaminergic neuron degeneration and αSyn aggregation. RTP801 was identified as a critical mediator of RBD-induced PD progression, with its sustained upregulation in dopaminergic neurons dependent on microglial activation. Mechanistically, initially activates microglia induced an increase in neuronal RTP801 via IL-6 and IL-8. RBD leaded to mitochondrial dysfunction, mtDNA release, and activation of the cGAS-STING pathway between neurons and microglia, triggering a mtDNA-cGAS-STING-IFNβ/RTP801 feedback loop, driving neurodegeneration. CONCLUSIONS: Our findings demonstrate that SARS-CoV-2 RBD exacerbates PD progression through a pathogenic crosstalk between microglia and neurons. This neurotoxic signaling is mediated by a mitochondrial mtDNA-cGAS-STING-IFNβ/RTP801 axis. Targeting RTP801 or the STING pathway may therefore represent a promising therapeutic strategy to mitigate long COVID-associated progression of PD.