Neutrophils Produce Interleukin 17A (IL-17A) in a Dectin-1- and IL-23-Dependent Manner during Invasive Fungal Infection

Abstract

ABSTRACTWe have previously reported that compromised interleukin 17A (IL-17A) production in the lungs increased susceptibility to infection with the invasive fungal pathogenAspergillus fumigatus. Here we have shown that culturing lung cells fromA. fumigatus-challenged miceex vivodemonstrated Dectin-1-dependent IL-17A production. In this system, neutralization of IL-23 but not IL-6, IL-1β, or IL-18 resulted in attenuated IL-17A production.Il23mRNA expression was found to be lower in lung cells fromA. fumigatus-challenged Dectin-1-deficient mice, whereas bone marrow-derived dendritic cells from Dectin-1-deficient mice failed to produce IL-23 in response toA. fumigatusin vitro. Addition of recombinant IL-23 augmented IL-17A production by wild-type (WT) and Dectin-1-deficient lung cells, although the addition of IL-6 or IL-1β did not augment the effect of IL-23. Intracellular cytokine staining of lung cells revealed lower levels of CD11b+IL-17A+and Ly-6G+IL-17A+cells inA. fumigatus-challenged Dectin-1-deficient mice. Ly-6G+neutrophils purified from the lungs ofA. fumigatus-challenged Dectin-1-deficient mice displayed lowerIl17amRNA expression but surprisingly had intactRorcandRoramRNA expression. We further demonstrated that Ly-6G+neutrophils required the presence of myeloid cells for IL-17A production. Finally, uponin vitrostimulation withA. fumigatus, thioglycolate-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.

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