A glycyrrhizin-containing preparation reduces hepatic steatosis induced by hepatitis C virus protein and iron in mice.

BACKGROUND/AIM: A European randomized trial showed biochemical effects of 6-month treatment with Stronger Neo-Minophagen C (SNMC), a glycyrrhizin-containing preparation, in patients with chronic hepatitis C, but its underlying mechanisms remain elusive. We reported previously that SNMC exhibits an anti-oxidative effect in hepatitis C virus (HCV) transgenic mice that develop marked hepatic steatosis with mitochondrial injury under iron overloading. Hepatic steatosis and iron overload are oxidative stress-associated pathophysiological features in chronic hepatitis C. The aim of this study was to investigate whether long-term treatment with SNMC could prevent the development of hepatic steatosis in iron-overloaded HCV transgenic mice. METHODS: C57BL/6 transgenic mice expressing the HCV polyprotein were fed an excess iron diet concomitantly with intraperitoneal injection of saline, SNMC, or seven-fold-concentrated SNMC thrice weekly for 6 months. RESULTS: Stronger Neo-Minophagen C inhibited the development of hepatic steatosis in a dose-dependent manner without affecting hepatic iron content, attenuated ultrastructural alterations of mitochondria of the liver, activated mitochondrial ß-oxidation with increased expression of carnitine palmitoyl transferase I and decreased the production of reactive oxygen species in the liver in iron-overloaded transgenic mice. However, SNMC hardly affected the unfolded protein response, which post-transcriptionally activates sterol regulatory element-binding protein 1, a transcription factor involved in lipid synthesis, even though we reported previously the activation of the unfolded protein response in the same iron-overloaded transgenic mice. CONCLUSIONS: These results suggest that SNMC prevents hepatic steatosis possibly by protecting mitochondria against oxidative stress induced by HCV proteins and iron overload.

Hepatitis C virus protein and iron overload induce hepatic steatosis through the unfolded protein response in mice.

BACKGROUND/AIM: Hepatic iron overload and steatosis play critical roles in the progression of hepatitis C virus (HCV)-associated chronic liver disease. However, how these two pathophysiological features affect each other remains unknown. The aim of this study was to investigate how hepatic iron overload contributes to the development of hepatic steatosis in the presence of HCV proteins. METHODS: Male C57BL/6 transgenic mice expressing the HCV polyprotein and nontransgenic littermates were fed an excess-iron diet or a control diet. Mice in each group were assessed for the molecules responsible for fat accumulation in the liver. RESULTS: Hepatic iron levels were positively correlated with triglyceride concentrations in the liver for all mice. As compared with the livers of nontransgenic mice fed the control diet, the livers of transgenic mice fed the excess-iron diet showed a lower expression of carnitine palmitoyl transferase I, a higher expression of sterol-regulatory element-binding protein 1 and fatty acid synthetase and an activated unfolded protein response indicated by a higher expression of unspliced and spliced X-box DNA-binding protein 1 (XBP-1), phosphorylated eukaryotic initiation factor-2alpha (p-eIF2alpha), CCAAT/enhancer-binding protein homology protein (CHOP) and abundant autophagosomes concomitant with increased production of reactive oxygen species. Six-month treatment with the anti-oxidant N-acetyl cysteine dramatically reduced hepatic steatosis in transgenic mice fed the excess-iron diet through decreased expression of unspliced and spliced XBP-1, p-eIF2alpha, and CHOP. CONCLUSIONS: The iron-induced unfolded protein response appears to be one of the mechanisms responsible for fat accumulation in the liver in transgenic mice expressing the HCV polyprotein.