The Alzheimer's disease peptide Aβ promotes thrombin generation through activation of coagulation factor XII

BACKGROUND: Beta-amyloid (Aβ) is a key pathological element in Alzheimer's disease (AD), but the mechanisms by which it disrupts neuronal function in vivo are not completely understood. AD is characterized by a prothrombotic state, which could contribute to neuronal dysfunction by affecting cerebral blood flow and inducing inflammation. The plasma protein factor XII (FXII) triggers clot formation via the intrinsic coagulation cascade and has been implicated in thrombosis.

OBJECTIVES: We investigated the potential for Aβ to contribute to a prothrombotic state.

METHODS AND RESULTS: We show that Aβ activates FXII, resulting in factor XI (FXI) activation and thrombin generation in human plasma, thereby establishing Aβ as a possible driver of prothrombotic states. We provide evidence for this process in AD by demonstrating decreased levels of FXI and its inhibitor C1 esterase inhibitor in AD patient plasma, suggesting chronic activation, inhibition, and clearance of FXI in AD. Activation of the intrinsic coagulation pathway in AD is further supported by elevated fibrin levels in AD patient plasma.

CONCLUSIONS: The ability of Aβ to promote coagulation via the FXII-driven contact pathway suggests new mechanisms by which it could contribute to neuronal dysfunction and identifies potential new therapeutic targets in AD. This article is protected by copyright. All rights reserved.