Project Summary/Abstract: Superfund site toxicants pose a significant hazard to human health, in part through their ability to alter patterns of gene expression. One of the most prevalent diseases, toxicant-associated steatohepatitis (TASH), is phenotypically similar to nonalcoholic steatohepatitis (NASH) without the underlying obesity. Building on this similarity, this project will provide mechanistic insight into TASH-induced liver damage and models of exposure. With a focus on the epigenetic and immune responses, the overall goal of the project is to identify potential intervention or prevention therapies and/or therapeutic targets. In Aim 1 we will explore the role of regulatory enhancers, key genomic mediators of tissue fibrosis, in mouse models of TASH by mapping injury-induced epigenetic changes in stellate cells, hepatocytes, and immune cells. In parallel studies, the therapeutic efficacy of epigenetically-targeted small molecule modulators will be determined in both intervention and prevention models of TASH. In Aim 2 we will profile the immune response to toxicant-induced liver damage in mice during the initial injury, damage/repair, and resolution stages. Based on these findings, potential immune-targeted therapies for the treatment TAFLD and TASH will be explored. In Aim 3, the epigenetic and immunological consequences of chronic toxicant exposure will be explored in a novel genetic mouse model of TAFLD (SMRTRID mice). In summary, this project will provide valuable insight on the molecular mechanisms underlying TAFLD and TASH as well as a roadmap for potential new therapies.