Circulating microparticle tissue factor activity Is increased in patients with cirrhosis

Abstract

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 cirrhosis patients. To determine if 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, had hepatocellular carcinoma, infection or transfusion within two weeks before blood draw. We also used 9 healthy volunteers as controls. All patients and controls gave their informed consent to participate to 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 with controls (Fig. 1C). MP TF activity correlated with MELD 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 while we used platelet free plasma.4 Figure 1 MP Procoagulant Activity In Patients With Cirrhosis 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, Fig. 1E). This lack of difference in levels of phosphatidylserine 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.