Liver stiffness in the hepatitis B virus carrier:A non-invasive marker of liver disease influenced by the pattern of transaminases

AIM： To investigate the usefulness of transient elastography by Fibroscan （FS）, a rapid non-invasive technique to evaluate liver fibrosis, in the management of chronic hepatitis B virus （HBV） carriers. METHODS： In 297 consecutive HBV carriers, we studied the correlation between liver stiffness （LS）, stage of liver disease and other factors potentially influencing FS measurements. In 87 chronic hepatitis B （CriB） patients, we monitored the FS variations according to the spontaneous or treatment-induced variations of biochemical activity during follow-up. RESULTS： FS values were 12.3 ± 3.3 kPa in acute hepatitis, 10.3 ± 8.8 kPa in chronic hepatitis, 4.3 ± 1.0 kPa in inactive carriers and 4.6 ± 1.2 kPa in blood donors. We identified the cut-offs of 7.5 and 11.8 kPa for the diagnosis of fibrosis ≥S3 and cirrhosis respectively, showing 93.9% and 86.5% sensitivity, 88.5% and 96.3% specificity, 76.7% and 86.7% positive predictive value （PPV）, 97.3% and 96.3% negative predictive value （NPV） and 90.1% and 94.2% diagnostic accuracy. At multivariate analysis in 171 untreated carriers, fibrosis stage （t = 13.187,P 〈 0.001）, active vs inactive HBV infection （t = 6.437, P 〈 0.001）, alanine aminotransferase （ALT） （t = 4.740, P 〈 0.001） and HBV-DNA levels （t = -2.046, P = 0.042） were independently associated with FS. Necroinflammation score （t = 2.158, 〉 10/18 vs ≤ 10/18, P = 0.035） and ALT levels （t = 3.566, P =0.001） were independently associated with LS in 83 untreated patients without cirrhosis and long-term biochemical remission （t = 4.662, P 〈 0.001） in 80 treated patients. During FS monitoring （mean followup 19.9 ± 7.1 mo） FS values paralleled those of ALT in patients with hepatitis exacerbation （with 1.2 to 4.4-fold increases in Crib patients） and showed a progressive decrease during antiviral therapy. CONCLUSION： FS is a non-invasive tool to monitor liver disease in chronic HBV carriers, provided that the pattern of biochemical activity is taken into account. In the inactive carrier, it identifies non-HBV-related causes of liver damage and transient reactivations. In CHB patients, it may warrant a more appropriate timing of control liver biopsies.

Bio-mathematical models of viral dynamics to tailor antiviral therapy in chronic viral hepatitis

The simulation of the dynamics of viral infections by mathematical equations has been applied successfully to the study of viral infections during antiviral therapy. Standard models applied to viral hepatitis describe the viral load decline in the f irst 2-4 wk of antiviral therapy, but do not adequately simulate the dynamics of viral infection for the following period. The hypothesis of a constant clearance rate of the infected cells provides an unrealistic estimation of the time necessary to reach the control or the clearance of hepatitis B virus (HBV)/ hepatitis C virus (HCV) infection. To overcome the problem, we have developed a new multiphasic model in which the immune system activity is modulated by a negative feedback caused by the infected cells reduction, and alanine aminotransferase kinetics serve as a surrogate marker of infected-cell clearance. By this approach, we can compute the dynamics of infected cells during the whole treatment course, and find a good correlation between the number of infected cells at the end of therapy and the long-term virological response in patients with chronic hepatitis C. The new model successfully describes the HBV infection dynamics far beyond the third month of antiviral therapy under the assumption that the sum of infected and non-infected cells remains roughly constant during therapy, and both target and infected cells concur in the hepatocyte turnover. In clinical practice, these new models will allow the development of simulators of treatment response that will be used as an "automatic pilot" for tailoring antiviral therapy in chronic hepatitis B as well as chronic hepatitis C patients.