PROJECT SUMMARY/ABSTRACT The virus, SARS-CoV-2 has caused COVID-19 and claimed the lives of over 240,000 Americans and 1,270,000 people worldwide. Severe cases of the disease leads to Acute Respiratory Distress Syndrome (ARDS), sepsis and can be fatal due to pulmonary inflammation and destruction of the epithelial and endothelial cell lining. Understanding the mechanisms behind these diseases is vital to develop effective preventive and therapeutic strategies. Staphylococcus enterotoxin B (SEB)-induced ARDS mimics the cytokine storm, sepsis and multiple organ failure presented in patients with severe COVID-19. It has been shown that the superantigen structure and sequence associated with the spike protein of the SARS-CoV-2 is similar to that of SEB. This SEB-induced ARDS model also results in various presentations of severity of illness in mice of different genetic backgrounds, as does COVID- 19 in humans. When C3H/HeJ mice are treated with SEB, their survival rate drops to 0%. In our study, we found that Cannabidiol (CBD) administration following SEB treatment, led to 100% survival indefinitely. Initial evaluation of whole single cell sequencing data comparing lungs from naïve with SEB-induced ARDS mice illustrated that there was an increase in neutrophils, inflammatory macrophages and pro-inflammatory cytokines (IL-1β and TNF-α) as well as a loss in lung epithelial cells. To characterize the mechanism by which CBD treatment led to amelioration of the inflammatory response, microRNA expression analysis was done that showed a significant decrease in expression of miR-124-3p in SEB-treated group which is directly associated with upregulation of TNF-α and IL-1β expression as well as macrophage activation gene, Cebp. We hypothesized that CBD attenuates SEB- induced ARDS by miRNA dysregulation in lung-infiltrating cells, specifically by inducing miR-124-3p which downregulates Cebp expression resulting in reduced activation of macrophages. Aim 1 will elucidate the role of resident and monocyte-derived macrophages in disease and the effect CBD on those subpopulations. Aim 2 will elucidate whether CBD affects Cebp expression and the effects that miR-124-3p has on manifestation of disease. Aim 3 will determine the epigenetic factors regulating expression of miR-124-3p. This study will explore CBD as a potential therapeutic for ARDS and/or sepsis induced not only by SEB but other pathogens such as SARS-CoV-2. The K99R00 will provide opportunities associated with Career Development and training in –omics approaches and biostatistics. Taken together, my mentors, advisory committee, consultant, and research environment at the University of South Carolina will nurture my successful transition to an Independent Investigator.