Project Abstract Alcoholic hepatitis (AH) is characterized by intense liver inflammation and injury in the setting of excess alcohol ingestion. Cytokine and chemokine upregulation leads to immune cell infiltration and drives inflammation in AH. Liver sinusoidal endothelial cells (LSEC) are an important source of chemokine expression in the liver and participate in paracrine signaling to attract immune cells in a process termed “angiocrine signaling”. Pathway analysis of AH liver RNA-sequencing suggests a potential role of IL17 in mediating LSEC angiocrine signaling. IL17 is a cytokine involved in many autoimmune and inflammatory disorders. Our preliminary data shows that IL17 synergically stimulate CXCL chemokine production with TNF, but the underlying mechanism is not clear. The regulation of IL17 production from T cells also requires further study. Super enhancers are DNA regulatory elements that complex with target gene promoters to drive gene expression. Our previous work has highlighted the role of super enhancers in AH inflammation response. Here, we hypothesize that LSECs increase inflammatory chemokine expression and enhance immune cell transmigration into the liver parenchyma in response to T cell IL17 upregulation by super enhancer activation. To test our hypothesis, we will employ complementary cell biologic and in vivo approaches to study the following specific aims: Aim 1. LSECs enhance CXCL1-dependent neutrophil transendothelial migration in response to IL17; Aim 2. Therapeutic targeting of a super enhancer in T cells downregulates IL17 and ameliorates inflammation in AH. In Aim 1, we will explore the role of IκB𝜁, a transcription factor previously implicated in IL17 signaling, in mediating the interaction between IL17 and TNF signaling pathways. We will also assess the transcriptomic changes of IL17 and TNF stimulation and IκB𝜁 silencing on LSECs by RNA-sequencing. Using microfluidic devices to simulate liver microvascular circulation, we will directly observe the effects of IL17/TNF stimulation and IκB𝜁 inhibition on neutrophil chemotaxis. In Aim 2, we will identify the IL17 super enhancer by chromosome conformation capture assays. We will assess the feasibility of CRISPR-mediated sequence-specific suppression of the IL17 super enhancer. We will use a Cre dependent dCas9-KRAB knockin mice with AAV6 viral delivery of single guide RNA to target the IL17 super enhancer in vivo. We aim to achieve T cell-specific suppression of IL17 expression and assess its effect on AH inflammatory response in a murine model. Indeed, in vivo CRISPR gene-editing has already been applied clinically to treat hereditary disorders, highlighting the translational promise of precision genome-targeting therapies. Better understanding of the IL17 mediated angiocrine signaling process and IL17 super enhancer regulation may reveal novel therapeutic targets for treatment of AH. Therefore, our overall aims and approaches are aligned with the mission of NIAAA ...