Yu Jun, Wu Chung W, Chu Eagle S H, Hui Alex Y, Cheng Alfred S L, Go Minnie Y Y, Ching Arthur K K, Chui Yiu L, Chan Henry L Y, Sung Joseph J Y
Institute of Digestive Disease and Department of Medicine and Therapeutics, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, China.
Biochem Biophys Res Commun. 2008 Aug 8;372(4):571-7. doi: 10.1016/j.bbrc.2008.05.069. Epub 2008 May 27.
Hepatic COX-2 overexpression is sufficient to induce hepatitis, but its role on liver fibrosis remains unknown. We aim to elucidate possible biological effects of COX-2 in liver fibrosis using both gain-of-function and loss-of-function mouse models. COX-2 transgenic (TG) mice that specifically overexpress the human COX-2 cDNA in the liver, knockout (KO), and wild type (WT) mice were studied in two different murine fibrosis models induced by carbon tetrachloride (CCl(4)) injection or methionine and choline-deficient (MCD) diet. Liver injury was assessed by serum ALT and bilirubin levels and histological examination. Hepatic collagen content was determined by picrosirius red stain morphometry assay and quantitation of hydroxyproline. Hepatic stellate cell (HSC) activation was determined by immunohistochemical analysis of alpha-smooth muscle actin (alpha-SMA). mRNA expression of fibrogenic genes was assayed by real-time quantitative PCR. COX-2 protein was overexpressed in the liver of TG mice compared with WT littermates. CCl(4) or MCD-induced liver fibrotic injury was equally severe in TG and WT mice, as demonstrated by similar elevated levels of hepatic collagen contents. Enhanced COX-2 expression in TG liver did not affect HSC activation and fibrogenic gene expression upon CCl(4) or MCD treatment. Importantly, CCl(4)-treated KO mice did not show significant difference in liver fibrotic damage and fibrogenic gene expression compared with the WT counterparts. This is the first report on the effect of COX-2 in liver fibrosis based on genetic mouse models. The results suggest that COX-2 does not appear to mediate the development of liver fibrosis.
肝脏中COX - 2的过表达足以诱发肝炎，但其在肝纤维化中的作用尚不清楚。我们旨在通过功能获得和功能丧失小鼠模型阐明COX - 2在肝纤维化中可能的生物学效应。在两种由四氯化碳（CCl₄）注射或蛋氨酸和胆碱缺乏（MCD）饮食诱导的不同小鼠纤维化模型中，研究了肝脏中特异性过表达人COX - 2 cDNA的COX - 2转基因（TG）小鼠、敲除（KO）小鼠和野生型（WT）小鼠。通过血清谷丙转氨酶（ALT）和胆红素水平以及组织学检查评估肝损伤。通过苦味酸天狼星红染色形态计量分析和羟脯氨酸定量测定肝脏胶原蛋白含量。通过α - 平滑肌肌动蛋白（α - SMA）的免疫组织化学分析确定肝星状细胞（HSC）的激活。通过实时定量PCR测定纤维化基因的mRNA表达。与野生型同窝小鼠相比，TG小鼠肝脏中COX - 2蛋白过表达。TG和WT小鼠中CCl₄或MCD诱导的肝纤维化损伤同样严重，肝脏胶原蛋白含量的升高水平相似证明了这一点。在CCl₄或MCD处理后，TG肝脏中增强的COX - 2表达不影响HSC激活和纤维化基因表达。重要的是，与野生型对照相比，CCl₄处理的KO小鼠在肝纤维化损伤和纤维化基因表达方面没有显示出显著差异。这是基于基因小鼠模型关于COX - 2在肝纤维化中作用的首次报道。结果表明COX - 2似乎不介导肝纤维化的发展。
