Neutrophils show distinct patterns of activation in the context of infection with different pathogens

Abstract Alternatively activated neutrophils (N2) enhance lung anti-helminth trained macrophage effector function in response to infection with the helminth Nippostrongylus. brasiliensis (Nb) (Fei Chen, et al., NI, 2014, CR, 2022). However, potential differences in activation patterns of neutrophils with different pathogens is not yet well studied. We report here lung neutrophils bear unique gene expression profiles at 2 days after infection with Nb, fungi (Aspergillosis fumigatus (Af)), and bacteria (Staphylococcus aureus (SA). AF and SA triggered genes associated with cell death and autophagy but differed greatly in metabolic activity. In contrast, Nb induced gene expression patterns characteristic of type 2 immunity, xenobiotic pathways, and cell proliferation. Further analysis revealed increased edu incorporation, KI-67 and IL-13 expression in neutrophils in the lung but not in the blood and bone marrow. Furthermore, the proliferating neutrophil subset predominantly expressed IL-13 and was IL-4R dependent. To directly examine neutrophils proliferating in the lung after Nb infection, Nb-primed neutrophils (CD45.2) were transferred to CD45.1 Nb inoculated recipients. At day 10 after inoculation, donor neutrophils were readily detected and were proliferating as measured by ki-67 staining and edu incorporation. These studies suggest that neutrophils exhibit distinct activation states following infection with different pathogens. Unlike neutrophils typically associated with microbial infection, where rapid turnover from cell death typically occurs, neutrophils activated following Nb infection persist and undergo cell cycling within the remodeled lung tissue microenvironment.