Factor X a Inhibitor Attenuates Leukocyte Adhesion and Thrombus Formation in an Experimental Mouse Model of the Metabolic Syndrome

AIMS: In a model of acute inflammation, Factor Xa inhibitors have been reported not only to suppress the coagulation system but also to exert anti-inflammatory effects. However, this has not been experimentally demonstrated in a model of chronic inflammation. Recent studies demonstrated that vascular inflammation in the metabolic syndrome plays major roles in the development of thrombotic diseases. Therefore, we examined the anti-inflammatory effects of fondaparinux, a Factor Xa inhibitor, in a mouse model of the metabolic syndrome, looking at both leukocyte adhesion on the vascular endothelium and thrombus formation. METHODS: Following clamping of the mesenteric vein for 20 min in the KK-A(y) mouse, mice were administered by subcutaneous injection either low-dose or high-dose fondaparinux or placebo (n = 10 in each group. Microscopic observation of the intestinal microcirculation was carried out. In another series, blood samples were taken and measured for blood cell counts and organ damage markers (n = 6 in each). RESULTS: Both leukocyte adherence and thrombus formation were inhibited by treatment with fondaparinux. Red blood cell and white blood cell counts were maintained better in high-dose group. Levels of alanine aminotransferase (ALT) were significantly reduced in both low-dose and high-dose groups (P < 0.05 and 0.01, compared with control, respectively). CONCLUSIONS: Factor Xa inhibitor attenuates leukocyte adhesion and leukocyte-platelet conjugate formation in a mouse model of the metabolic syndrome. These effects appeared to be related to both inhibition of thrombus formation and reduction in markers of organ damage.