Red blood cell-derived transglutaminase 2 influences thrombus formation

Area of Science:

• Biochemistry
• Hematology
• Cell Biology

Background:

• Red blood cells (RBCs) are integral to venous clot formation and stability.
• The precise role of RBCs in thrombus development and the influence of Transglutaminase 2 (TG2) remain under investigation.
• TG2, an enzyme with Factor XIIIa-like activity, may impact clot characteristics.

Purpose of the Study:

• To investigate the role of RBC-derived TG2 in modulating thrombus characteristics.
• To utilize a novel approach employing TG2 knockout (KO) RBCs to explore TG2's function in clots.

Main Methods:

• Clotting assays were performed using TG2 inhibitors and TG2 KO RBCs.
• Advanced microscopy quantified fibrin networks in vitro.
• Thrombin generation assays and thromboelastography assessed whole blood clotting kinetics.
• Microparticle flow cytometry analyzed vesiculation.

Main Results:

• Clots formed with TG2 KO RBCs or TG2 inhibition showed reduced and thinner fibrin fibers on the surface.
• TG2 inhibition led to fibrin redistribution deeper into the clot.
• TG2 inhibition accelerated thrombin generation and clot formation, indicated by shortened lag times and faster kinetics.
• TG2 inhibition increased extracellular vesicle (EV) formation and phosphatidylserine exposure on RBC membranes.

Conclusions:

• RBC-derived TG2 activity specifically regulates EV formation, influencing fibrin structure and distribution within clots.
• The absence of TG2 activity promotes increased EV formation, leading to accelerated thrombin generation and clot formation.
• TG2 plays a regulatory role in coagulation kinetics, particularly through its effects on RBC-derived EVs.