Early normalization of reduced urea synthesis capacity after direct-acting antiviral therapy in hepatitis C cirrhosis.

Laursen TL, Sandahl TD, Kazankov K, Eriksen PL, Kristensen LH, Holmboe CH, Laursen AL, Vilstrup H, Grønbæk H. Early normalization of reduced urea synthesis capacity after direct-acting antiviral therapy in hepatitis C cirrhosis. Am J Physiol Gastrointest Liver Physiol 319: G151-G156, 2020. First published June 29, 2020; doi:10.1152/ajpgi.00128.2020.-Effects of direct-acting antiviral (DAA) treatment of chronic hepatitis C (CHC) cirrhosis on metabolic liver function are unknown but important for prognosis. Ureagenesis is an essential metabolic liver function involved in whole body nitrogen homeostasis. We aimed to investigate the ureagenesis capacity before and immediately after DAA therapy and relate the findings to hepatic inflammation and structural changes. In an observational before-and-after intervention study, the ureagenesis capacity was quantified by functional hepatic nitrogen clearance (FHNC) in 9 CHC patients with cirrhosis and 10 healthy volunteers. Hepatic inflammation was evaluated by alanine aminotransferase (ALT) and the macrophage activation markers sCD163 and sMR. Structural changes were estimated as liver stiffness and by portal hypertension as the hepatic venous pressure gradient (HVPG). Before treatment, the FHNC in the patients was half of the controls [16.4 L/h (8.2-24.5) vs. 33.4 (29.2-37.6), P = 0.0004]; after successful DAA treatment, it normalized [28.4 (15.9-40.9), P = 0.008 vs. baseline]. DAA treatment normalized ALT (P < 0.0001) and decreased the elevated sCD163 from 5.6 mg/L (3.5-7.7) to 3.4 (2-0-4.8) (P < 0.001) and sMR from 0.35 mg/L (0.21-0.49) to 0.31 (0.17-0.45) (P < 0.01). Liver stiffness fell by 30% (P < 0.05) but remained over the cirrhosis threshold. HVPG was not affected (P = 0.59). DAA treatment restored the severely reduced ureagenesis capacity, along with amelioration of hepatic inflammation but without normalization of other cirrhosis characteristics. Our findings indicate that the anti-inflammatory effect of virus eradication independent of hepatic structural effects rapidly improves metabolic dysfunction. We suggest this effect to be an important early onset part of the expected clinical DAA treatment benefit.NEW & NOTEWORTHY Antiviral treatment of chronic hepatitis C restores the liver's reduced capacity to produce urea along with an improvement in liver inflammation without immediate effects on structural liver changes. The effect is suggested to be an important early onset part of the expected clinical treatment benefit.