Abstract
Background: Non-alcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance and hepatic steatosis. Non-alcoholic steatohepatitis (NASH) is a serious consequence of NAFLD where chronic tissue damage and inflammation result in fibrosis which may progress to cirrhosis. Transforming growth factor beta 1 (TGF beta 1), proinflammatory cytokines and oxidative stress are thought to play crucial roles in the pathogenesis of these conditions. The contributions of individual liver cell types to fibrogenesis remain controversial and the influence of selenium status has not been investigated.
Methods: In this study we have used a cell culture model of fat-loading using oleate-treated human hepatoblastoma (C3A) cells to investigate how fat-loading and selenium status might influence the production of collagen in response to TGF beta 1. The secretion of inflammatory cytokines was also investigated, together with the epithelial character of the treated cells.
Results: We found that in response to treatment with TGF beta 1, C3A cells produced mRNA encoding the pro-alpha I chain of procollagen I. secreted procollagen I peptide, up-regulated production of the proinflammatory cytokine interleukin-8 (IL-8) and the mesenchymal marker vimentin, and down-regulated albumin production. Most of these responses were considerably enhanced when cells were fat-loaded with oleate and were attenuated by selenium addition at a dose that optimised the expression of thioredoxin reductase and glutathione peroxidase.
Conclusions: Our data establish that both fat-loading and suboptimal selenium status enhance collagen and IL-8 production by C3A hepatocytes in response to TGF beta 1, possibly as part of an epithelial to mesenchymal transition.
General significance: These findings suggest that the hepatocyte may be an important contributor to the pathogenesis of fibrosis associated with NAFLD. (C) 2010 Elsevier B.V. All rights reserved.