Antithrombotic Mechanisms in Endothelial Function

The vascular endothelium serves as a dynamic antithrombotic barrier by integrating surface-bound anticoagulant factors, synthesising glycocalyx components and coordinating anti‐adhesive and anti‐coagulant pathways. Central to this role are heparan sulfate proteoglycans that bind and present antithrombin to inhibit thrombin and factor Xa, and thrombomodulin that transforms thrombin into a promoter of protein C activation. The endothelial glycocalyx further supports antithrombotic defence by resisting platelet and leukocyte adhesion under shear flow. Endothelial cells also regulate tissue factor pathway inhibitor release and express ectonucleotidases to degrade pro‐aggregatory nucleotides. Inflammatory stimuli and disturbed flow can degrade these mechanisms, shifting the endothelium towards a procoagulant phenotype. Restoration of antithrombotic function hinges on reconstitution of glycocalyx integrity, upregulation of anticoagulant receptors and controlled mechanotransduction through shear‐responsive signalling pathways.

Research from Nature Portfolio

Recent studies have elucidated the shear‐dependent remodelling of endothelial cell surfaces, showing that pulsatile flow enhances clustering of heparan sulfate chains to increase antithrombin binding affinity. A second investigation identified a novel splice variant of thrombomodulin that potentiates protein C activation under high‐shear conditions, offering protection against microvascular thrombosis without impairing haemostasis. A further report characterised the role of endothelial caveolae in localising antithrombotic receptors to regions of laminar flow, revealing that disruption of caveolar trafficking leads to reduced surface expression of both thrombomodulin and heparan sulfate proteoglycans, thereby promoting fibrin deposition in experimental vessels.

Antithrombotic Mechanisms in Endothelial Function publication trend

The graph below shows the total number of articles in antithrombotic mechanisms in endothelial function across all publications each year (not limited to Nature Index journals).

Technical terms

Endothelial glycocalyx: A carbohydrate‐rich layer on the luminal surface of endothelial cells that inhibits cell adhesion and binds anticoagulant proteins.

Heparan sulfate proteoglycan: A matrix molecule composed of a core protein and sulfated glycosaminoglycan chains that act as a scaffold for antithrombin and other regulators.

Thrombomodulin: An endothelial surface receptor that binds thrombin, switching its specificity to activate protein C.

Protein C: A vitamin K‐dependent zymogen that, once activated, degrades clotting factors Va and VIIIa to limit thrombin generation.

Antithrombin: A serine protease inhibitor that irreversibly inactivates thrombin and factor Xa, whose activity is greatly enhanced by heparin or heparan sulfate.

Shear stress: The frictional force generated by blood flow that influences endothelial gene expression and antithrombotic phenotype.

References

1. Dexamethasone Preconditioning in Cardiac Procedures Reduces Decreased Antithrombin Activity and Is Associated to Beneficial Outcomes: Role of Endothelium. Frontiers in Pharmacology (2018).
2. Synthesis of Anticoagulantly Active Heparan Sulfate Proteoglycans by Glomerular Epithelial Cells Involves Multiple 3-O-Sulfotransferase Isoforms and a Limiting Precursor Pool*. Journal of Biological Chemistry (2005).
3. Antithrombin significantly influences platelet adhesion onto immobilized fibrinogen in an in-vitro system simulating low flow. Thrombosis Journal (2006).