Modeling HCV infection, immunopathogenesis, and therapy in humanized mice

Washburn, Michael L.

Modeling HCV infection, immunopathogenesis, and therapy in humanized mice Public Deposited

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March 22, 2019

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Washburn, Michael L.
- Affiliation: School of Medicine, Curriculum in Genetics and Molecular Biology

Abstract

Approximately 170 million people worldwide are chronically infected by the hepatitis C virus (HCV), which is often associated with impaired T cell responses to viral antigens, chronic liver inflammation, fibrosis/cirrhosis, and hepatocellular carcinoma. Current therapies for HCV are limited by low efficacy and detrimental side-effects, leaving many patients with poor quality of life. Understanding HCV infection, immunopathogenesis, and development of improved therapies for HCV is hampered by the lack of a robust model system. In this dissertation, I establish a novel humanized mouse model to study HCV infection, immunopathogenesis, and therapies to overcome the immune tolerance, liver inflammation, fibrosis, and liver cancer that characterize HCV infection. To achieve this goal, I first established a mouse model to study persistently expressed foreign antigens in the liver by infection with liver tropic adeno-associated virus (AAV) vector. I demonstrated that expressing LIGHT with an adenovirus vector (Ad) in mice with established AAV vectors in the liver led to clearance of the AAV, correlating with enhanced CD8 effector T cells in the liver and inflammation. Interestingly, Ad-LIGHT cleared AAV but caused no significant liver inflammation in LT[beta]R-null mice. These findings shed light on developing novel immuno-therapeutics to treat people chronically infected with hepato-tropic viruses. I next developed an improved humanized mouse model designed to study human hepato-tropic viruses and their interaction with both the human immune system and liver. I created transgenic Rag2-/- [gamma]c-/- mice with the FKBP-caspase 8 fusion gene expressed from the albumin enhancer/promoter (AFC8/DKO). Inducible apoptosis of mouse hepatocytes enables transplanted human hepatocyte progenitor cells (Hep) and CD34+ hematopoietic stem/progenitor cells (HSC) to selectively repopulate the liver and thereby providing us with a highly functional mouse model containing a human immune system and liver. Finally, I showed that AFC8/DKO mice, transplanted with human Hep and HSC (AFC8/DKO-hu HSC/Hep), are susceptible to HCV infection. I further demonstrate that the mice develop a human immune response to HCV, leading to liver fibrosis. The AFC8/DKO-hu HSC/Hep mouse model will greatly advance the study of HCV infection, immunopathogenesis, and development of improved therapies to combat infection and liver disease progression.

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