Alcoholic liver disease is a major clinical challenge because it is associated with severe complications like liver cirrhosis and alcoholic hepatitis, which carry a high mortality. Our understanding of the mechanisms underlying alcoholic liver disease is still evolving; however, previous research has identified cells involved in the liver's response to alcohol-induced injury, including myofibroblasts, macrophages and oval cells (called ductular reaction in humans). Because of their unique and important functions, each of these cell types is a promising therapeutic target. Macrophages initiate and promote liver inflammation and activate hepatic stellate cells, which leads to the formation of collagen-secreting myofibroblasts and liver fibrosis and cirrhosis. Other types of macrophages resolve fibrosis and oval cells may produce new hepatocytes, although oval cell accumulation does not appear to prevent liver failure in patients with alcoholic hepatitis. Efficient gene delivery to these cell types would facilitate inhibiting or activating these functions, which would have many applications in research and therapy of alcoholic liver disease. To achieve this overall goal, we aim to target nonintegrating nontoxic adenoassociated viral (AAV) vectors to (1) myofibroblasts, (2) macrophage subsets, i.e., Kupffer cells and pro- inflammatory and anti-inflammatory infiltrating macrophages, and (3) oval cells in vivo. For this, we formed a collaboration that combines our expertise in AAV vector engineering and the cellular and molecular biology of liver injury and regeneration. To facilitate specific experimentation and support clinical translation, we will not only target AAV vectors to each of these cell types but also detarget them from every other organ and cell type in the body using a workflow that combines state-of-the-art AAV capsid evolution technology, faithful mouse models of alcoholic liver disease, next-generation sequencing-based analysis of vector biodistribution and on- target and off-target regulation of vector gene expression. To demonstrate the efficacy of the new synthetic AAV capsids, we will use them to determine which of the targeted cell types is most susceptible to in vivo reprogramming into hepatocytes. We hypothesize that oval cells can be most efficiently induced to become hepatocytes because they derive from closely related cholangiocytes or hepatocytes themselves. Therefore, in addition to providing efficient and precise tools for studies of alcohol-induced liver injury, the proposed project may establish opportunities for new therapies for liver failure and other life-threatening complications of alcoholic liver disease.
Adenoassociated viral vectors proved to be safe and effective in recent clinical trials of liver-directed gene therapy. To help realize the potential of these vectors for research and therapy of alcoholic liver disease, we will target them to cells involved in the liver's response to alcohol toxicity.