Dectin-1-Dependent Interleukin-22 Contributes to Early Innate Lung Defense against Aspergillus fumigatus

Abstract

We have previously reported that mice deficient in the beta-glucan receptor Dectin-1 displayed increased susceptibility toAspergillus fumigatuslung infection in the presence of lower interleukin 23 (IL-23) and IL-17A production in the lungs and have reported a role for IL-17A in lung defense. As IL-23 is also thought to control the production of IL-22, we examined the role of Dectin-1 in IL-22 production, as well as the role of IL-22 in innate host defense againstA. fumigatus. Here, we show that Dectin-1-deficient mice demonstrated significantly reduced levels of IL-22 in the lungs early afterA. fumigatuschallenge. Culturing cells from enzymatic lung digestsex vivofurther demonstrated Dectin-1-dependent IL-22 production. IL-22 production was additionally found to be independent of IL-1β, IL-6, or IL-18 but required IL-23. The addition of recombinant IL-23 augmented IL-22 production in wild-type (WT) lung cells and rescued IL-22 production by lung cells from Dectin-1-deficient mice.In vivoneutralization of IL-22 in the lungs of WT mice resulted in impairedA. fumigatuslung clearance. Moreover, mice deficient in IL-22 also demonstrated a higher lung fungal burden afterA. fumigatuschallenge in the presence of impaired IL-1α, tumor necrosis factor alpha (TNF-α), CCL3/MIP-1α, and CCL4/MIP-1β production and lower neutrophil recruitment, yet intact IL-17A production. We further show that lung lavage fluid collected from bothA. fumigatus-challenged Dectin-1-deficient and IL-22-deficient mice had compromised anti-fungal activity againstA. fumigatus in vitro. Although lipocalin 2 production was observed to be Dectin-1 and IL-22 dependent, lipocalin 2-deficient mice did not demonstrate impairedA. fumigatusclearance. Moreover, lungS100a8,S100a9, andReg3gmRNA expression was not lower in either Dectin-1-deficient or IL-22-deficient mice. Collectively, our results indicate that early innate lung defense againstA. fumigatusis mediated by Dectin-1-dependent IL-22 production.