PROJECT SUMMARY/ABSTRACT Sepsis is a common and deadly disease and treatment options are limited to antibiotics and supportive care. Endotoxemia is a key feature of sepsis pathogenesis and can also contribute to numerous other inflammatory disorders. Growing antibiotic resistance and an aging population have contributed to an urgent unmet need for new therapeutics for these conditions. This K08 proposal will complete the training that will launch the independent career of Vinitha Jacob, MD, PhD, a physician scientist in emergency medicine. She seeks to complement her expertise in zebrafish development with additional training in mammalian systems to reach her long-term goal of developing both novel and repurposed therapeutics for sepsis and other acute diseases. In Dr. Jacob’s recently published work, she used the endotoxin lipopolysaccharide (LPS) to recapitulate key features of sepsis pathogenesis. RNA sequencing (RNA-seq) identified cholesterol metabolism as one of the most significantly altered pathways in LPS treated zebrafish and sepsis patients with poor outcomes. Specifically, the mRNA for 7-dehydrocholesterol reductase (DHCR7), which catalyzes the conversion of 7- dehydrocholesterol (7-DHC) to cholesterol, was significantly upregulated in LPS treated zebrafish and was one of only two lipid-related gene associated with mortality in sepsis patients. Dr. Jacob made the novel finding that fish treated with a DHCR7-specific inhibitor were completely protected from endotoxemic death. In her specific aims, she will build on these findings and interrogate the mechanisms by which DHCR7 inhibition protects from endotoxemia (Aim 1), test whether DHCR7 inhibition can also relieve LPS toxicity a mammalian model (Aim 2) and identify clinically used DHCR7 inhibitors (Aim 3) that can be considered for repurposing for acute human inflammatory diseases including sepsis. These aims will elucidate the role of DHCR7 in endotoxemia and will identify clinically utilized DHCR7 inhibitors that mediate LPS toxicity. In completing the proposed aims under the guidance of established mentors and leaders Dr. Shavit (genome editing), Dr. Dickson (mammalian endotoxemia/sepsis) and Dr. Schwendeman (cholesterol metabolism), Dr. Jacob will complement her experience in zebrafish development with knowledge in cholesterol metabolism and hands-on-training in genome editing techniques and mammalian models of endotoxemia. The fertile training ground at the University of Michigan, with its strong history of developing successful physician scientists, combined with an experienced mentorship team with relevant expertise will allow Dr. Jacob to emerge from this career development award period as a uniquely trained emergency medicine physician-scientist with expertise in both zebrafish and mammalian systems. She will thus have the ability take her findings from initial discovery across the translational spectrum.

PROJECT NARRATIVE Sepsis, or dysregulated host response to infection, is one of the most common causes of hospitalization in the U.S. with a high mortality rate. DHCR7, an enzyme involved in cholesterol synthesis, was associated with mortality in human sepsis, and fish treated with a DHCR7 inhibitor were protected from toxicity in a zebrafish model that recapitulates features of human sepsis. This proposal will clarify the mechanisms by which inhibition of this enzyme exerts a protective effect, with implications for the development of human sepsis therapeutics.