In A53T/PFF mice, sleep deprivation selectively upregulates astrocytic LAG3, which disrupts AQP4 polarization and glymphatic α-synuclein clearance to worsen motor deficits and neurodegeneration, and astrocyte-specific AAV-mediated LAG3 knockdown restores clearance and attenuates pathology.

Points to astrocytic LAG3 as an actionable, potentially repurposable target that links sleep loss to α-syn accumulation and PD progression, offering a translational avenue for patients with sleep disturbances pending human validation and safety assessment.

INTRODUCTION: Parkinson's disease (PD) progression is strongly associated with sleep disturbances, but the molecular mechanisms linking sleep loss to PD pathology remain poorly understood. Emerging evidence implicates impaired glymphatic clearance of pathological α-synuclein (α-syn) as a key factor, though how sleep deprivation disrupts this process is unclear. OBJECTIVES: This study aimed to determine whether sleep deprivation exacerbates PD pathology by modulating lymphocyte-activation gene 3 (LAG3) expression in astrocytes, thereby impairing glymphatic system function and promoting α-syn accumulation. METHODS: We injected α-syn preformed fibrils (PFF) into the striatum of A53T transgenic mice and subjected them to sleep deprivation. Glymphatic function was assessed using in vivo magnetic resonance imaging and fluorescent tracer-based clearance assays. Astrocytic LAG3 expression was evaluated by transcriptomic sequencing and validated by immunostaining and qPCR. Adeno-associated virus-mediated LAG3 knockdown in astrocytes was used to test causality. RESULTS: Sleep deprivation significantly worsened motor deficits, dopaminergic neuron loss, and α-syn pathology in PD mice. It induced astrocyte reactivity and disrupted aquaporin-4 (AQP4) polarization, leading to impaired cerebrospinal fluid influx and reduced α-syn clearance. LAG3 was selectively upregulated in astrocytes under sleep-deprived conditions and promoted α-syn PFF internalization. Knockdown of astrocytic LAG3 restored AQP4 polarization, improved glymphatic clearance, and attenuated neurodegeneration and behavioral deficits. CONCLUSION: Our findings identify astrocytic LAG3 as a critical mediator linking sleep deprivation to glymphatic dysfunction and PD progression. Targeting LAG3 may represent a promising, albeit early-stage, therapeutic strategy to mitigate α-syn pathology in PD patients with sleep disorders.