Characterization of structural and functional liver changes in a transgenic mouse model expressing genotype 1a hepatitis C virus core and envelope proteins 1 and 2
Creators: name: Naas, Turaya
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2007
Subjects: subject: Health Sciences, Immunology.

description: Hepatitis C virus (HCV) is a major cause of chronic hepatitis affecting over 170 million people worldwide. The mechanisms behind the pathogenesis of chronic HCV infection are not well understood. The aim of this thesis is to elucidate how the HCV structural proteins affect the dynamic structural and functional properties of hepatocytes and measure the extra-hepatic manifestations induced by these viral proteins. To pursue this goal, a transgenic mouse model was established by expressing Core, E1 and E2 proteins downstream of a CMV promoter. HCV RNA was detected in transgenic mouse model tissues, such as liver, kidney, spleen, and heart. Immunofluorescence analysis revealed the expression of core, E1 and E2 proteins predominantly in hepatocytes. Histological analysis of liver cells demonstrated steatosis in transgenic mice older than 3 months, which progressed with mouse age. Electron microscopy analysis revealed alterations in mitochondria, and in the endoplasmic reticulum. The animals became more prone to liver and lymphoid tumor development and hepatocellular carcinoma. It is likely that the HCV structural proteins mediate some of the histological alterations in hepatocytes by interfering with liver biological processes. To study that, we compare differential gene expression patterns in the liver of HCV transgenic and non-transgenic mice using complementary DNA (cDNA) microarrays and confirmed the expression of altered genes by real-time RT-PCR. 15 600 genes were analyzed and 394 genes were identified to be differentially expressed at a statistically significant level, while 196 genes were identified as up-regulated and 198 genes were identified as down-regulated. The expression of HCV structural proteins in transgenic mouse livers induces alterations in the expression of genes involved in many important biological processes such as lipid metabolism and transport, antigen processing and presentation, protein biosynthesis, carcinogenesis, etc. Also, some of the differentially expressed genes were associated with important cell signaling pathways such as Mitogen activated protein kinase (MAPK) pathway and Writ oncogenic pathway. The third study aims to elucidate the role of immune-mediated cell damage in hepatitis C infection using HCV Transgenic mice. Adoptive transfer of carboxyfluorescein diacetate suuccinimidyl ester (CFSE) labelled splenocytes from HCV immunized mice into HCV transgenic mice was performed. After the adoptive transfer, we observed that there was a significant decrease in the percentage of CFSE-labeled CD4+ and CD8+ T cells in the blood of transgenic mice receiving transfers from immunized donors. Moreover, the percentage of CFSE-labeled CD4+ and CD8+ T cells were significantly higher in the spleen of transgenic and non-transgenic mice when they received transfer from non-immunized mice. Interestingly, transgenic livers of mice received transfers from immunized mice had significantly high percentage of CFSE-labeled T cells than non-transgenic livers receiving non-immunized transfers. This suggests that the T cells from HCV immunized mice recognized HCV antigens in the liver. Taken together, the research results indicate that our transgenic mouse model is a suitable model to study hepatitis C pathogenesis.