Abstract
Background
F11Receptor/junctional adhesion molecule-A (F11R/JAM-A) is a transmembrane protein
expressed in endothelial cells, epithelial cells, and in blood platelets. In blood
platelets, F11R/JAM-A participates in adhesion under static conditions, suppresses
the activation of the platelet αIIbβ3 integrin and was shown to activate blood platelets as soluble form via homophilic
interactions.
Objectives
The purpose of presented study was to evaluate whether F11R/JAM-A is involved in platelet
adhesion under flow conditions and in thrombus formation.
Methods
F11R/JAM-A contribution to platelet adhesion under flow conditions was assessed using
flow chamber assay. Monoclonal antibodies and recombinant F11R/ JAM-A were used to
assess the effects of F11R/JAM-A blockade on platelet aggregation and thrombus formation
using total thrombus formation analysis system. Effects of F11R/JAM-A blockade on
thrombus formation in vivo were evaluated in murine models of carotid artery injury.
Results
F11R/JAM-A was not capable of capturing flowing blood platelets alone but enhanced
platelet adhesion to fibrinogen under flow conditions. Blocking of F11R/JAM-A homophilic
interactions with specific monoclonal antibodies or with recombinant F11R/JAM-A impaired
thrombus formation in vitro in human blood and in vivo in the models of thrombosis
in mice.
Conclusion
Interactions of F11R/JAM-A located on flowing platelets with its surface-bound counterpart
enhance platelet binding to fibrinogen under high shear stress conditions. Blocking
of these homophilic interactions compromises thrombus formation. While previously
published studies pointed at a significant role of soluble F11R/JAM-A in priming platelets
during thrombus formation, our results highlight the role of surface-bound F11R/JAM-A
in this process.
Keywords
junctional adhesion molecule-A (F11R/JAM-A) - platelets - adhesion - thrombosis