373 Identification of potential targets for immunotherapy in a cynomolgus macaque model of Ebola virus disease

OBJECTIVES/GOALS: Ebola virus infection causes severe disease and liver injury in humans. Macrophages contribute to inflammatory signaling and are prevalent in the liver. We assessed the activation status, including therapeutic target expression, of hepatic macrophages. METHODS/STUDY POPULATION: We compared formalin-fixed, paraffin-embedded liver tissue from terminal Ebola virus-infected and uninfected control cynomolgus macaques, a gold-standard model for human disease. We characterized region-specific protein and whole transcriptome expression in these tissues using GeoMx Digital Spatial Profiling. Macrophage (CD68+) and leukocyte (CD45+) accumulation in liver tissue was quantified by immunofluorescence image analysis using digital pathology software. RESULTS/ANTICIPATED RESULTS: Macrophage-specific (CD68+) regions in the liver of Ebola virus-infected macaques demonstrated a shift towards an inflammatory gene expression profile, as compared to those from healthy control tissue. These regions showed differential expression of monocyte/macrophage differentiation, antigen presentation, and T cell activation gene sets, which were associated with decreased MHC-II allele expression. Moreover, macrophage-specific regions in the infected macaques showed enriched expression of genes or proteins associated with known immunomodulatory therapeutics, including S100A9, IDO1, and CTLA-4. DISCUSSION/SIGNIFICANCE: These data demonstrate that hepatic macrophages express an inflammatory phenotype, that their ability to present antigens to the adaptive immune system may be impaired, and that they express therapeutically targetable markers for immunomodulation of these cells during Ebola virus infection.