Mechanism of IL-17–mediated host defense against OPC. (A) Oral inoculation with C. albicans induces Th17 signature genes in oral mucosal tissue, which are suppressed in IL-17RA^KO mice. Tongue tissue from female WT or IL-17RA^KO mice (n = 2, from independent experiments) was taken at baseline (day 0) or 24 h after oral C. albicans inoculation (day 1), and cDNA was prepared and hybridized to Affymetrix genechips. Shown are Th17-related genes found to be induced on day 1 compared with day 0 from WT mice (red bars) or IL-17RA^KO mice (white bars). (B) Differentially expressed genes in WT versus IL-17RA^KO mice determined by microarray analysis. Fold change of genes induced in WT mouse tongue compared with IL-17RA^KO tongue on day 1 are indicated. * indicates genes previously connected to IL-17 or Th17 cells. (C–J) OPC-induced expression of selected genes. Tongue mRNA from WT or IL-17RA^KO mice on day 0 or day 1 (mRNA from two mice from independent experiments) was subjected to quantitative real-time RT-PCR analysis in triplicate. Data are presented as fold induction, normalized to GAPDH. *, P < 0.05 compared with WT Day 0; ‡, P < 0.05 compared with IL-17RA^KO Day 0.