[Role of transforming growth factor-beta in the development of some liver diseases]

To investigate the expression of transforming growth factor-beta 1 (TGF-beta1) in the liver tissue of patients with autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and chronic hepatitis C (CHC).

Liver biopsy specimens were histologically and immunohistologically examined in 37 patients with verified liver diseases (12 with AIH, 15 with PBC, and 10 with CHC).

The expression of TGF-beta1 in the non-parenchymal liver cells of the patients with AIH and PBC with liver cirrhosis was statistically significantly higher than in those without the latter (p = 0.01 and p = 0.04, respectively). There was a positive relationship between the stage of fibrosis and the absolute content TGF-beta1 and CD68+ cells in the portal tracts (r = 0.51). The higher expression of TGF-beta1 was found in the patients with HCV and AIH than in those with PBC (p = 0.03 and p < 0.05, respectively). There were no differences in the expression of TGF-beta1 in the patients with AIH as compared to those with CHC (p = 0.55). The number of CD68-positive macrophages was higher in CHC than in AIH and PBC (p = 0.004 and p = 0.01, respectively). In autoimmune liver diseases, TGF-beta1 was mainly expressed by the macrophages located in the portal tracts and, in CHC, within the hepatic lobules.

The enhanced TGF-beta1 expression in the nonparenchymal liver cells in AIH and PBC with liver cirrhosis confirms the role of this cytokine in development of fibrosis in autoimmune liver diseases. That in hepatitis of various etiologies versus PBC suggests that the TGF-beta1 signaling pathway may play an important role in an inappropriate immune response in hepatitides; and the variations found in the location of the macrophages expressing TGF-beta1 reflect a difference in the mechanisms of lesions.