Spectral immune cell profiling reveals modulations in immune cell response to repetitive inhaled organic dust exposure in a high omega-3 fatty acid mouse model.

Exposure of the lungs to particulate matter (i.e. dust, wildfire smoke, air pollution) places individuals at an increased risk for developing chronic respiratory disease. Recent work has demonstrated the efficacy of omega-3 fatty acids and their metabolites in promoting the resolution of prolonged inflammation, however a comprehensive understanding of how omega-3 fatty acid balance impacts immune cell populations and crosstalk remains undescribed. We developed a 17-marker, 14-color spectral flow cytometry method to characterize the immunophenotypic changes in the bronchoalveolar space and lung tissue following 14 days of repetitive organic dust exposure or PBS vehicle. The populations of immune cells were compared in C57BL/6 (WT) and a transgenic model of increased omega-3 fatty acid (Fat-1) mice. Histopathologic examination revealed no difference between WT and Fat-1 mice at baseline or following organic dust exposure. Immune cell makeup within the bronchoalveolar space and lung tissue differed between WT and Fat-1 mice, with and without organic dust exposure. Fat-1 mice demonstrated a monocyte-dominant response compared to WT in both the airway and the lung tissue. Intriguingly, this monocyte-dominance was more prominent in female Fat-1 mice in the lung tissue and male Fat-1 mice in the airway. This suggests that monocyte populations are preferentially loaded following organic dust exposure in the lung and airways as a result omega-3 fatty acid metabolite-linked resolution processes, and that sex-dependent factors in this immune response are pivotal to consider in therapeutic strategies aimed at mitigating disease.