Immunohistochemical distribution of activated nuclear factor kappaB and peroxisome proliferator-activated receptors in carbon tetrachloride-induced chronic liver injury in rats.

We investigated the immunohistochemical distribution of active NF-kappaB p65 and peroxisome proliferator-activated receptor (PPAR) subtypes alpha and gamma in the different phases of liver steatonecrosis and cirrhosis induced in rats after 3 and 9 weeks of carbon tetrachloride (CCl4) intoxication. CCl4 treatment can induce changes in the expression of NF-kappaB and PPARs. Immunohistochemical analysis of liver tissue sections from rats with steatonecrosis or cirrhosis demonstrated a significant increase in the number of NF-kappaB-positive and TNF-alpha-positive hepatocytes and Kupffer cells. In healthy controls, no expression of active NF-kappaB was detected. In previous studies, we have demonstrated that Kupffer cells isolated from rats with CCl4-induced steatonecrosis produced more reactive oxygen intermediates than cells isolated from normal rats. These oxidants could activate NF-kappaB and lead to an overexpression of TNF-alpha, observed in liver tissue sections. After CCl4 ingestion, the rat livers demonstrated a significantly decreased number of hepatocytes expressing PPARalpha and PPARgamma and a significantly increased number of ED2-positive Kupffer cells expressing these transcription factors, compared to normal. The activation of the p65 isoform of NF-kappaB correlates negatively with transcription of the alpha and gamma isoforms of PPAR in hepatocytes, and positively in Kupffer cells. These results suggest that the regulation and the role of these two transcription factors differ in the two cell types studied.

Hepatic metallothionein in patients with chronic hepatitis C: relationship with severity of liver disease and response to treatment.

OBJECTIVES: Reactive oxygen species may be involved in the pathogenesis of chronic hepatitis C virus infection. Metallothionein (MT) is an essential protein for the protection of cells against reactive oxygen species. The aim of this prospective study was to assess the influence of the hepatic level and cellular distribution of MT in hepatitis C virus (HCV) infection and in the liver disease outcome. METHODS: In liver biopsy samples of 32 patients with chronic HCV infection and of 12 control subjects, quantification of MT was performed by radioimmunoassay, MT, interleukin (IL)-1 and -6, and tumor necrosis factor (INF)-alpha mRNA by reverse transcription-polymerase chain reaction (PCR) and cellular distribution by immunohistochemistry. RESULTS: In HCV-infected patients, MT liver protein level was 3-fold lower than in control specimens. A significant inverse linear regression between MT protein or mRNA expression and the Histological Activity Index, the necroinflammatory grade, and the stage of fibrosis was observed. MT immunostaining was located in the nucleus and cytoplasm in hepatocytes of control subjects, whereas it was mainly cytoplasmic in HCV-infected patients. Before interferon (IFN) therapy, the hepatic MT level in patients that were nonsustained responders was half that of sustained responders. Intrahepatic IL-6 and MT were simultaneously down-regulated, but no correlation was found between MT and intrahepatic cytokine mRNA expression in patients with chronic HCV infection. CONCLUSIONS: This study shows that hepatic MT expression could reflect the severity of chronic HCV infection and could be one of the factors associated with a favorable clinical outcome in the response to interferon therapy.