Induced forms of α-macroglobulin neutralize heparin and direct oral anticoagulant effects.

Alpha-macroglobulin (αM) is a physiological macromolecule that facilitates the clearance of many proteinases, cytokines and growth factors in human. Here, we explored the effect of induced forms of αM on anticoagulant drugs. Gla-domainless factor Xa (GDFXa) and methylamine (MA)-induced αM were prepared and characterized by electrophoresis, immunonephelometry, chromogenic, clot waveform and rotational thromboelastometry assays. Samples from healthy volunteers and anticoagulated patients were included. In vivo neutralization of anticoagulants was evaluated in C57Bl/6JRj mouse bleeding-model. Anticoagulant binding sites on induced αM were depicted by computer-aided energy minimization modeling. GDFXa-induced αM neutralized dabigatran and heparins in plasma and whole blood. In mice, a single IV dose of GDFXa-induced αM following anticoagulant administration significantly reduced blood loss and bleeding time. Being far easier to prepare, we investigated the efficacy of MA-induced αM. It neutralized rivaroxaban, apixaban, dabigatran and heparins in spiked samples in a concentration-dependent manner and in samples from treated patients. Molecular docking analysis evidenced the ability of MA-induced αM to bind non-covalently these compounds via some deeply buried binding sites. Induced forms of αM have the potential to neutralize direct oral anticoagulants and heparins, and might be developed as a universal antidote in case of major bleeding or urgent surgery.