Marburg I polymorphism of factor VII--activating protease: a prominent risk predictor of carotid stenosis.

BACKGROUND: Atherothrombosis is a main pathomechanism in the evolution of vessel stenosis and is counteracted by endogenous fibrinolysis. Recently, the plasmatic serine protease "factor seven-activating protease" (FSAP) was recognized as a potent activator of prourokinase in vitro. The Marburg I polymorphism of FSAP impairs this potential and may thus facilitate arterial thrombosis. METHODS AND RESULTS: This analysis of the Bruneck Study involved 810 men and women aged 40 to 79 years. The ultrasound-based atherosclerosis progression model (5-year follow-up) permits differentiation between early atherogenesis and the advanced stenotic stages of carotid artery disease. The FSAP Marburg I polymorphism was found in 37 subjects (carriage rate 4.4%). Individuals with this genetic variant showed a prominently reduced in vitro capacity to activate prourokinase. No relation was found to exist between the Marburg I polymorphism and early atherogenesis. In contrast, it emerged as a strong and independent risk predictor of incident/progressive carotid stenosis (multivariate odds ratio [95%CI], 6.6 [1.6 to 27.7]). This finding equally applied to subjects with and without co-segregation of the Marburg II polymorphism. The risk profile of advanced atherogenesis further includes cigarette smoking, high lipoprotein(a), the factor V Leiden mutation, low antithrombin III, high fibrinogen, and diabetes. CONCLUSIONS: In concert with other genetic and acquired conditions known to interfere with coagulation or fibrinolysis, the Marburg I polymorphism of FSAP, which attenuates its capacity to activate prourokinase, is a significant risk predictor for the evolution and progression of carotid stenosis.

Antithrombin, heparin, and heparan sulfate.

OBJECTIVES: To review the experimental and clinical evidence that antithrombin has multiple mechanisms for both its anticoagulant and anti-inflammatory properties. The interaction between antithrombin and specific polysulfated, acidic oligosaccharide moieties found on heparin and related proteoglycan molecules within the circulation and on endothelial surfaces will also be examined. DATA SOURCES: Review of the literature relating to antithrombin published during the past 25 yrs. DATA SUMMARY: Antithrombin is the most abundant endogenous anticoagulant circulating in human plasma. This serine protease inhibitor participates in the regulation of clotting in both physiologic and pathologic states. Reduced antithrombin activity in the early phases of sepsis contributes to a procoagulant state with excess activation of the innate immune response. Antithrombin binds to specific pentasaccharides expressed on heparin, glycosaminoglycans, and related proteoglycans within the circulation and along endothelial surfaces. The functions of neutrophils, monocytes, and endothelial cells are altered as a result of their interaction with antithrombin. These effects are mediated by the enzyme inhibitory action of antithrombin and its ability to function as a ligand for antithrombin receptors on cell surfaces. In addition, antithrombin exerts anti-inflammatory properties by both prostacyclin-dependent and prostacyclin-independent actions; heparin interferes with these anti-inflammatory properties. The role of antithrombin in sepsis, its therapeutic utility in severe sepsis, and its combination with heparin remain the subject of considerable debate. The results of a recent phase 3 clinical trials with high-dose antithrombin in sepsis suggested a beneficial effect in patients who did not concomitantly receive heparin, thereby generating new challenges in the understanding of interactions between antithrombin and heparin or heparin-like proteoglycans. CONCLUSIONS: Antithrombin has complex interactions with host coagulopathic and systemic inflammatory responses under physiologic conditions and in sepsis. The impact of these interactions in critically ill patients and the therapeutic implications of administration of antithrombin, and various doses and types of heparin in such patients, need further clarification.