Peri-arterial pathways for clearance of α-Synuclein and tau from the brain: Implications for the pathogenesis of dementias and for immunotherapy.

ABSTRACT

INTRODUCTION: Accumulation of amyloid beta (Aß), α-synuclein (αSyn), and tau in dementias indicates their age-related failure of elimination from the brain. Aß is eliminated along basement membranes in walls of cerebral arterioles and leptomeningeal arteries (intramural peri-arterial drainage [IPAD]); IPAD is impaired with age. We test the hypothesis that αSyn and tau are also eliminated from the normal brain along IPAD pathways. METHODS: Soluble αSyn or tau was injected into mouse hippocampus. Animals were perfused 5 minutes to 7 days post-injection. Blood vessels were identified by ROX-SE for light-sheet and immunolabeling for confocal microscopy. IPAD was quantified by measuring the proportion of arterioles with αSyn/tau. RESULTS: αSyn and tau are eliminated from the brain by IPAD but with different dynamics. DISCUSSION: Age-related failure of IPAD may play a role in the pathogenesis of synucleinopathies and tauopathies. αSyn persists within IPAD at 24 hours, which may affect immunotherapy for αSyn.