Background: Platelet-endothelial cell interactions play a key role in hemostasis and pathological coagulation and are dependent on different surface molecules that are expressed upon activation (eg, mediated by lipopolysaccharide [LPS]). Recently, we have shown that Rho kinase plays a central role in LPS-mediated leukocyte-endothelial cell interactions. We investigated the role of Rho-kinase in inflammatory interactions between platelets and the endothelium in femoral veins in vivo.
Methods: Mice were injected intravenously with LPS (0.5 mg/kg)/D-galactosamine (900 mg/kg), and Rho kinase was blocked with fasudil 15 minutes before LPS application. Four hours after LPS administration, intravital fluorescence microscopy of the femoral vein was performed, and primary and secondary platelet-endothelial cell interactions were visualized after in vivo platelet staining with rhodamine 6G.
Results: Intravital microscopy showed a significant increase in platelet tethering, rolling, and firm adhesion as well as platelet secondary capture in LPS-treated mice. Rho-kinase inhibition by fasudil significantly reduced platelet tethering, rolling, and firm adhesion. Interestingly, functional blockade of Rho kinase was also able to diminish secondary platelet capture by 79%.
Conclusions: From our data, we conclude that Rho-kinase signaling plays a central role in the regulation of LPS-induced platelet-endothelial cell interactions in large veins in vivo. Thus, Rho-kinase inhibition might be useful in prevention or treatment of pathological inflammation and endotoxin-mediated hypercoagulation.