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Oropharyngeal candidiasis (OPC) is an opportunistic infection of the oral mucosa caused by the commensal fungus Candida albicans. IL-17 and IL-22 both mediate antifungal immunity yet activate distinct downstream signaling pathways. While much is known about IL-17-dependent immunity in OPC, the activities of IL-22 are less well delineated. We show that induction of Il22 is independent of Dectin-1, CARD9 and aryl hydrocarbon receptor (AhR) and is driven by IL-23 and the C. albicans pore forming peptide candidalysin. Despite similar induction requirements and cellular sources, IL-22 and IL-17 function non-redundantly during OPC and exert opposing roles in neutrophil recruitment. The IL-22 and IL-17 receptors are required in anatomically distinct locations; loss of IL-22RA1 in the oral basal epithelial layer (BEL) but not the suprabasal epithelial layer (SEL) causes susceptibility to OPC, whereas IL-17RA is needed in the SEL. Our data reveal that IL-22 is a major activator of STAT3 in the BEL during OPC. Moreover, loss of STAT3 in the BEL but not the SEL renders mice susceptible to OPC. Transcriptional profiling of RNASeq data linked IL-22/STAT3 to oral epithelial cell proliferation and survival, but also, unexpectedly, to driving an IL-17 gene signature. We show that IL-22 acts on the BEL to replenish the IL-17RA-expressing SEL, thereby restoring the ability of the oral epithelium to respond to IL-17. Consequently, IL-22 signaling in BEL ‘licenses’ IL-17R signaling in the oral epithelium, revealing spatially distinct yet cooperative activities of IL-22 and IL-17 in oral candidiasis. This work also suggests that oral thrush in Jobs’ syndrome patients may be caused by STAT3 impairments in the oral epithelium, not just Th17 cells.

Systemic candidiasis (SC) is a leading cause of nosocomial bloodstream infections, with mortality of >40% despite therapy. In a mouse model of SC, the most highly infected organ is the kidney, and myeloid cells, including dendritic cells (DCs), are integral for host defense. We hypothesized that Ccr7, which mediates DC trafficking and survival, is critical for host defense during SC. Ccr7 and its ligands, Ccl19 and Ccl21, were highly up-regulated in the Candida-infected kidney. All Ccr7−/− mice rapidly succumbed during SC, whereas WT mice had 80% survival at day 14. Infected Ccr7−/− mice had significantly greater kidney fungal burden, with greater tissue damage, and more severe renal failure. Infection in Ccl19−/− mice and in plt/plt mice (that lack Ccl19 and the CCL21a isoform of Ccl21) did not phenocopy the susceptibility of Ccr7−/− mice, indicating that the CCL21b-Ccr7 axis is critical for protection. Surprisingly, bone marrow chimeras revealed that the protective effects of Ccr7 are solely mediated by non-hematopoietic cells. Studies using FACS, IHC, and mRNA from sorted renal cells showed that Ccr7 is expressed by renal tubular cells (RTCs), not other renal stromal cells. Our preliminary data show the Ccr7 is a survival factor for RTCs; indeed, Ccr7 deficiency resulted in significantly greater tubulitis and tubular necrosis during SC. The renal protective effects of Ccr7 were also evident during bacterial sepsis, indicating that Ccr7 is broadly protective against infection-induced acute kidney injury. In summary, our data are the first to implicate Ccr7 in innate control of any pathogen and to uncover the contribution of Ccr7 on non-hematopoietic cells in protection against acute kidney injury and systemic fungal infection.