Circulating microparticle tissue factor activity Is increased in patients with cirrhosis

Cirrhosis is associated with a procoagulant imbalance.1 Reduced expression of the anticoagulants, protein C and antithrombin, and increased expression of the procoagulants, factor VIII and von Willebrand factor, may increase coagulation in these patients.1 Levels of procoagulant microparticles (MPs) and, particularly, MPs carrying the highly procoagulant protein tissue factor (TF) have not been investigated in patients with cirrhosis. To determine whether MP TF activity is increased in patients with cirrhosis, we analyzed 33 patients with alcoholic and/or hepatitis C virus–related cirrhosis (10 Child-Pugh A, 9 Child-Pugh B, and 14 Child-Pugh C) using a previously reported assay.2 None used drugs known to interfere with coagulation or had hepatocellular carcinoma, infection, or transfusion within 2 weeks before blood draw. We used 9 healthy volunteers as controls. All patients and controls gave their informed consent to participate in the study, which was approved by the institutional review board. Levels of markers of activation of coagulation and fibrinolysis increased with cirrhosis severity (Fig. 1A,B). As expected, plasma from healthy individuals contained very low levels of MP TF activity.2 Importantly, MP TF activity increased with cirrhosis severity and was 17-fold higher in Child-Pugh C patients, compared to controls (Fig. 1C). MP TF activity correlated with the Model for End-Stage Liver Disease score (Spearman's correlation: r = 0.523; P = 0.002). Similarly, when restricting the analyses to the 22 patients with a relatively stable condition (outpatients or planned hospitalization), we observed higher MP TF activity in patients with cirrhosis than in controls (P = 0.007). A previous study reported that MP TF activity was increased 38-fold in acute liver injury/acute liver failure patients.3 This study used platelet-poor plasma, whereas we used platelet-free plasma.4 We also assessed levels of total MPs, but did not observe any difference between patients and controls either using flow cytometry (Annexin V binding; Fig. 1D) or an activity assay (Zymuphen MP Activity; HYPHEN BioMed, Andresy, France; Fig. 1E). This lack of difference in levels of phosphatidylserine (PS)-positive MPs may be because the majority of these MPs are derived from platelets and we have found that platelet-derived MPs are not increased in cirrhosis.4 In conclusion, patients with cirrhosis have increased levels of circulating MP TF activity that may contribute to the activation of coagulation and thrombosis in these patients. The authors thank Martin Baunacke, Rebecca Lee, Jian-Guo Wang, and Ying Zhang for their skilled technical assistance. We thank Yacine Boulaftali and Dominique Valla for helpful discussions. Pierre-Emmanuel Rautou, M.D., Ph.D.1, 2Anne-Clémence Vion, Ph.D.3James P. Luyendyk, Ph.D.4Nigel Mackman, Ph.D.1 1Department of Medicine Division of Hematology and Oncology McAllister Heart Institute University of North Carolina at Chapel Hill Chapel Hill, NC 2Service d'Hépatologie Hôpital Beaujon Assistance Publique-Hôpitaux de Paris Clichy, France 3INSERM U970Paris Cardiovascular Research Center–PARCCUniversité Paris Descartes Sorbonne Paris CitéParis, France 4Department of Pathobiology and Diagnostic Investigation Michigan State University East Lansing, MI