We have previously reported that compromised IL-17A production in the lungs increased susceptibility to infection with the invasive fungal pathogen Aspergillus fumigatus. Here, we show that culturing lung cells from A. fumigatus-challenged mice ex vivo demonstrated Dectin-1 dependent IL-17A production. In this system, neutralization of IL-23, but not IL-6, IL-1ß or IL-18, resulted in attenuated IL-17A production. Il23 mRNA expression was found to be lower in lung cells from A. fumigatus-challenged Dectin-1 deficient mice whereas bone marrow-derived dendritic cells from Dectin-1 deficient mice failed to produce IL-23 in response to A. fumigatus in vitro. Addition of recombinant IL-23 augmented IL-17A production by WT and Dectin-1 deficient lung cells, although the addition of IL-6 or IL-1ß did not augment the effect of IL-23. Intracellular cytokine staining of lung cells revealed lower CD11b+ IL-17A+ and Ly-6G+ IL-17A+ cells in A. fumigatus-challenged Dectin-1 deficient mice. Ly-6G+ neutrophils purified from the lungs of A. fumigatus-challenged Dectin-1 deficient mice displayed lower Il17a mRNA expression, but surprisingly had intact Rorc and Rora mRNA expression. We further demonstrate that Ly-6G+ neutrophils required the presence of myeloid cells for IL-17A production. Finally, upon in vitro stimulation with A. fumigatus, thioglycollate-elicited peritoneal neutrophils were positive for intracellular IL-17A expression and produced IL-17A in a Dectin-1 and IL-23 dependent manner. In summary, Dectin-1 dependent IL-17A production in the lungs during invasive fungal infection is mediated in part by CD11b+ Ly-6G+ neutrophils in an IL-23 dependent manner.
Werner, J. L., Gessner, M. A., Lilly, L. M., Nelson, M. P., Metz, A. E., Horn, D., Dunaway, C. W., Deshane, J., Chaplin, D. D., Weaver, C. T., Brown, G. D., & Steele, C. (2011). Neutrophils produce IL-17A in a Dectin-1 and IL-23 dependent manner during invasive fungal infection. Infection and Immunity, 79(10), 3966-3977. https://doi.org/10.1128/IAI.05493-11