Plasma and hepatic tissue levels of thrombomodulin, tissue factor, NFkappaB and nitric oxide in responders and nonresponders to IFNalpha therapy.

Abstract

Hepatitis C virus (HCV) infects hepatocytes and utilizes the hepatocyte to replicate. In so doing, many hepatocyte activities are shifted from their native state to one reflecting liver cell stress. Thrombomodulin and tissue factor are endothelial cell proteins that are expressed as a result of tissue injury or stress. Urokinase is a serine protease, which has been implicated in a number of physiologic and pathologic processes related to cellular stress and or injury. Nitric oxide is produced by cells in response to injury and functions both as a vasodilator and as an activator of a large number of cytokine cascades. NFkappaB is a transcription factor that forms one of the first lines of cellular defense against infection and hepatocellular stress. The levels of these four factors in plasma, hepatocyte cytosol and hepatocyte nuclear extracts provide a precise panoramic measure of cellular stress. Plasma, hepatocyte cytosol and nuclear extracts of hepatocytes were assayed for these four factors in 17 patients treated with alphaIFN for chronic hepatitis C. Five of the 17 were responders while 12 were nonresponders. Ten normal controls and 1 normal control liver were assayed also for each parameter. Nonresponders had 2x the plasma urokinase levels of responders and normals. The cytosol prepared from hepatocytes of nonresponders had a urokinase level 15-fold that of the controls and responders to IFN therapy. Plasma thrombomodulin levels in nonresponders were sixfold greater than those of responders and controls. The levels of all of the other measures in plasma, cytosol and nuclear extracts of liver tissue varied minimally between responders and nonresponders and the normal controls. These data demonstrate that: (i) urokinase levels in plasma and more clearly in cytosol are greater in nonresponders than responders, and (ii) plasma thrombomodulin levels in nonresponders are sixfold greater than those of responders and controls. These data suggest that urokinase and thrombomodulin may be unique markers of cellular and endothelial stress present in individuals with chronic hepatitis C. These markers might be useful during the clinical course of chronic hepatitis C, as a means of gauging the tissue response to therapy.