Blocking meningeal lymphatic drainage aggravates Parkinson's disease-like pathology in mice overexpressing mutated α-synuclein

Background: Abnormal aggregation of brain alpha-synuclein is a central step in the pathogenesis of Parkinson's disease (PD), thus, it is reliable to promote the clearance of alpha-synuclein to prevent and treat PD. Recent studies have revealed an essential role of glymphatic system and meningeal lymphatic vessels in the clearance of brain macromolecules, however, their pathophysiological aspects remain elusive. Method: Meningeal lymphatic drainage of 18-week-old A53T mice was blocked via ligating the deep cervical lymph nodes. Six weeks later, glymphatic functions and PD-like phenotypes were systemically analyzed. Results: Glymphatic influx of cerebrospinal fluid tracer was reduced in A53T mice, accompanied with perivascular aggregation of alpha-synuclein and impaired polarization of aquaporin 4 expression in substantia nigra. Cervical lymphatic ligation aggravated glymphatic dysfunction of A53T mice, causing more severe accumulation of alpha-synuclein, glial activation, inflammation, dopaminergic neuronal loss and motor deficits. Conclusion: The results suggest that brain lymphatic clearance dysfunction may be an aggravating factor in PD pathology.