Clarke Catriona, Baghdadi Hussam, Howie Alexander F, Mason J Ian, Walker Simon W, Beckett Geoffrey J
Clinical Biochemistry, Western General Hospital, Edinburgh, UK.
Biochim Biophys Acta. 2010 Jun;1800(6):611-8. doi: 10.1016/j.bbagen.2010.02.007. Epub 2010 Feb 23.
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 beta1 (TGFbeta1), 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.
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 TGFbeta1. The secretion of inflammatory cytokines was also investigated, together with the epithelial character of the treated cells.
We found that in response to treatment with TGFbeta1, C3A cells produced mRNA encoding the pro-alphaI 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.
Our data establish that both fat-loading and suboptimal selenium status enhance collagen and IL-8 production by C3A hepatocytes in response to TGFbeta1, possibly as part of an epithelial to mesenchymal transition.
These findings suggest that the hepatocyte may be an important contributor to the pathogenesis of fibrosis associated with NAFLD.
非酒精性脂肪性肝病（NAFLD）与肥胖、胰岛素抵抗及肝脂肪变性相关。非酒精性脂肪性肝炎（NASH）是NAFLD的严重后果，慢性组织损伤和炎症导致纤维化，进而可能发展为肝硬化。转化生长因子β1（TGFβ1）、促炎细胞因子及氧化应激被认为在这些疾病的发病机制中起关键作用。单个肝细胞类型对纤维化形成的作用仍存在争议，且尚未研究硒状态的影响。
在本研究中，我们使用油酸处理的人肝癌细胞（C3A）建立脂肪加载细胞培养模型，以研究脂肪加载和硒状态如何影响C3A细胞对TGFβ1反应时胶原蛋白的产生。同时还研究了炎性细胞因子的分泌以及处理后细胞的上皮特性。
我们发现，在TGFβ1处理后，C3A细胞产生编码I型前胶原α1链的mRNA，分泌I型前胶原肽，上调促炎细胞因子白细胞介素-8（IL-8）和间充质标志物波形蛋白的产生，并下调白蛋白的产生。当细胞用油酸进行脂肪加载时，这些反应大多显著增强，而添加能优化硫氧还蛋白还原酶和谷胱甘肽过氧化物酶表达的剂量的硒可减弱这些反应。
我们的数据表明，脂肪加载和硒状态欠佳均会增强C3A肝细胞对TGFβ1反应时胶原蛋白和IL-8的产生，这可能是上皮-间充质转化的一部分。
这些发现表明，肝细胞可能是与NAFLD相关的纤维化发病机制的重要促成因素。
