IDO1-dependent day–night changes of the host response to A. fumigatus infection. (A) Ido1 gene expression, Kyn, and Trp levels in lung homogenates from WT and IDO1 KO mice. All values are the mean + SEM (n = 7–8). Student's t-test, significant changes are shown. **P < 0.01, n.d., not detectable. (B-E) IDO1 KO mice (n = 3–6 mice per group) were infected intranasally with live A. fumigatus conidia at two ZT, together with C57BL/6 wild-type described in Fig. 3. (B) Lung CFU were assessed at 1, 3, and 7 dpi in IDO1 KO. Black bars indicate the geometric mean (n = 3–6). P-values were generated by two-way ANOVA test, Bonferroni post-hoc test. No statistically significant changes were found. (C) BAL cellular morphometry, expressed as means of total and differential cell counts ± SEM are presented. P-values were generated by two-way ANOVA test, Bonferroni post-hoc test, significant changes are shown. ****P < 0.0001 for PMN, ++++ P < 0.0001 and ++ P < 0.01 for total cells. (D) Lung histology studied by periodic acid–Schiff staining. Scale bars 200 μm. In (E), mouse pro-inflammatory cytokines measured by multiplex immunoassay in lung homogenates of IDO1 KO mice. (n = 3–4). All the values are the mean ± SEM, *P < 0.05, **P < 0.01, ***P < 0.001. Two-way ANOVA, Bonferroni post-hoc test.