Aquaporin-4 and caveolin-1 as mediators of fibrinogen-driven cerebrovascular pathology in cerebral amyloid angiopathy.

INTRODUCTION

Cerebral amyloid angiopathy (CAA), marked by amyloid beta (Aβ) accumulation in perivascular spaces (PVSs), contributes to vascular injury and inflammation in Alzheimer's disease. The mechanisms underlying CAA-related vascular pathology remain unclear. Increasing evidence indicates fibrinogen, the main component in blood clots, interacts with Aβ and exacerbates inflammation and co-deposits in PVS of CAA-positive vessels, yet its role in cerebrovascular dysfunction remains poorly defined.

METHODS

Using TgSwDI transgenic mice, which develop robust CAA, we examined fibrin(ogen) deposition, aquaporin-4 (AQP4) polarization, and caveolin-1 (Cav-1) expression. We further assessed the effects of fibrinogen depletion via small interfering RNA.

RESULTS

TgSwDI mice showed increased fibrin(ogen) extravasation, colocalization with Aβ in PVS, AQP4 depolarization, and elevated Cav-1 expression. Fibrinogen depletion reduced CAA, restored AQP4 polarization, decreased Cav-1 levels, attenuated microglial activation, and improved spatial memory.

DISCUSSION: These findings suggest that modulating fibrinogen-related pathways could be a promising strategy for mitigating CAA pathology and its associated cerebrovascular pathology.

HIGHLIGHTS: Fibrin(ogen)-Aβ colocalization aggravates CAA. AQP4 depolarization links fibrinogen-Aβ deposits to impaired clearance in CAA. Cav-1 increase drives fibrinogen leakage and neuroinflammation. Fibrinogen depletion reduces CAA, restores AQP4 polarity, and improves memory.