Enhanced expression of interleukin-6 in chronic hepatitis C.

AIMS/BACKGROUND: There is a possibility that proinflammatory cytokines such as interleukin-6 (IL-6) are involved in the inflammatory process of chronic hepatitis C. This study was undertaken to investigate the possible role of IL-6 in the pathophysiology of chronic hepatitis C. METHODS: Serum IL-6 levels in 63 patients with chronic hepatitis C and in 26 normal controls were measured. Light and electron immunostaining studies to localize IL-6 protein as well as in situ hybridization to localize IL-6 messenger RNA were performed on 10 liver biopsy specimens. RESULTS: Serum IL-6 levels were significantly (p<0.01) elevated in chronic hepatitis C compared to those in normal controls. Although no statistically significant correlation was found between serum IL-6 levels and hepatobiliary enzyme levels, a significant correlation (p<0.01) was found between serum IL-6 levels and category II of Knodell's histological activity index score. Non-parenchymal cells in hepatic sinusoids and the cells infiltrating enlarged fibrous portal tracts were definitely positive for IL-6 protein and mRNA by immunohistochemistry and in situ hybridization. In addition, immunoelectron microscopy revealed a weak and occasional positive reaction in the cytoplasm of hepatocytes. The majority of the positive cells in hepatic sinusoids showed CD68 immunoreactivity in consecutive sections indicating that these were Kupffer cells. Sinusoidal endothelial cells and hepatic stellate cells also exhibited a weak reaction. CONCLUSION: These results strongly suggest that Kupffer cells in liver parenchyma and macrophages infiltrating in portal tracts are the main producers of elevated IL-6 in serum. Moreover, there is a possibility that IL-6 produced by hepatocytes could also act as a regenerative stimulus to hepatocytes themselves in an autocrine fashion.

Expression, localization and alternative splicing pattern of fibronectin messenger RNA in fibrotic human liver and hepatocellular carcinoma.

BACKGROUND/AIMS: Fibronectin is a multifunctional glycoprotein and plays important roles in cell-to-cell or cell-to-matrix interaction. The molecular and functional diversity of fibronectin arises from alternative splicing of pre-mRNA at three variable regions, termed ED-A, ED-B and IIICS. Cellular fibronectin with ED-A and ED-B regions has different biological activities from plasma fibronectin lacking these regions. This study was aimed at investigating the type-specific expression of fibronectin in human liver diseases. METHODS: Immunohistochemistry with anti-total and anti-cellular fibronectin monoclonal antibodies, in situ hybridization with cDNA probes detecting common and ED-A regions and RT-PCR to amplify each variable region were performed in 35 specimens, including 4 control, 16 chronic hepatitis, 7 liver cirrhosis and 8 hepatocelular carcinoma. RESULTS: In control liver, there were slight deposits of cellular fibronectin [ED-A(+)fibronectin] in portal areas. In chronic hepatitis, it was strongly deposited at the margin of the fibrously enlarged portal areas where new collagen fibers were formed. Cellular fibronectin was evenly and abundantly accumulated in fibrotic septa in liver cirrhosis, and in fibrotic septa and capsules of tumor nodules in hepatocellular carcinoma. In control liver, cellular fibronectin mRNA was localized in a few hepatocytes and non-parenchymal cells around central veins, and was increased in the same cell populations near fibrously enlarged portal areas as hepatic fibrosis progressed. In hepatocellular carcinoma, it was expressed in most hepatoma cells. Fibronectin mRNA with three variable regions was detectable by RT-PCR in control liver as well as in each disease group. CONCLUSIONS: The expression of cellular fibronectin was increased in fibrotic human liver and hepatocellular carcinoma. In human liver, both non-parenchymal cells and hepatocytes participated together in cellular fibronectin production. In hepatocellular carcinoma, hepatoma cells were the main producer. Our results indicate that, in human liver, cellular fibronectin may participate in the hepatic fibrogenesis and in the malignant phenotypes of hepatocellular carcinoma.

Immunolocalization of a fibronectin-binding proteoglycan (PG-P1) immunologically related to HSPG2/perlecan in normal and fibrotic human liver.

Immunolocalization of a fibronectin-binding proteoglycan (PG-P1) in relation to fibronectin, type IV collagen and laminin, in normal and fibrotic human liver was investigated by light and electron microscopy. HS-42, which is a monoclonal antibody to PG-P1 and is reported to recognize a heparan sulfate proteoglycan named HSPG2/perlecan, was used for this purpose. Light microscopy in the human liver with minimal changes revealed that PG-P1 was present along the hepatic sinusoids as well as fibronectin and type IV collagen, whereas laminin was only weakly detected. In portal areas, PG-P1 was only localized on basement membranes around bile duct systems and blood vessels, as well as laminin and type IV collagen, while fibronectin was scarcely detected in basement membranes. In the fibrotic liver, fibronectin was abundant in necrotic and/or newly fibrosing areas, while PG-P1 was absent in these regions. Using immunoelectron microscopy, PG-P1 was localized in the space of Disse in nearly normal livers and was only detected on basement membranes in portal tracts. In fibrotic livers, PG-P1 in the space of Disse occasionally showed a basement-membrane-like deposition in parallel with the increased light microscopical deposition of laminin in this area, suggesting the positive participation of PG-P1 in the sinusoidal capillarization. Most capillary and sinusoidal endothelial cells, and rarely bile epithelial cells revealed the reaction products of PG-P1 in their rough endoplasmic reticulum and small vesicles. Thus, it was suggested that these cell types are mainly, if not wholly, responsible for PG-P1 production.(ABSTRACT TRUNCATED AT 250 WORDS)