Fig 2: Anoxia activates both IDO activity-derived pathways. Cells were cultured under anoxic conditions for 24 h along with the indicating treatments. Anoxia activated the GCN2K pathway assessed by the level of phosphorylated activated GCN2K. 1-MT, but not CH223191, prevented GCN2K activation. A representative Western blot experiment is displayed in panel (A), whereas panel (B) depicts the cumulative results of four repeated experiments. Anoxia activated the AhR pathway assessed by the level of the AhR transcriptional target CYP1A1. Both the IDO inhibitor 1-MT and the AhR inhibitor CH223191 prevented AhR activation. A representative Western blot experiment is displayed in panel (C), whereas panel (D) depicts the cumulative results of four repeated experiments. * p < 0.05 vs. Control, # p < 0.05 vs. Control with 1-MT, ^ p < 0.05 vs. Control with CH223191, & p < 0.05 vs. Anoxia, + p < 0.05 vs. Anoxia with 1-MT, ! p < 0.05 vs. Anoxia with CH223191. Error bars correspond to SEM. 1-MT, 1-DL-methyltryptophan; CYP1A1, cytochrome P450, family 1, subfamily A, polypeptide 1; GCN2K, general control nonderepressible 2 kinase; p-GCN2K, phosphorylated GCN2K.

Fig 3: Cyp1a1 deficiency alters the gut microbiota composition. (A) Chao 1 index and (B) Shannon index measuring bacterial richness and diversity by 16S rDNA sequencing in the caecal content of Cyp1a1+/+ mice and Cyp1a1–/– mice with or without MRSA infection (n = 8–9). (C) The unweighted UniFrac-based 3D-PCoA showed obvious differences in the gut microbiota composition between mice in (A) (n = 8–9). (D) Bar chart of the relative microbiome abundance at the phylum level from mice as in (A). (E) The cladogram based on LEfSe analysis shows bacterial taxa (class, order, family, and genus) differentially abundant in Cyp1a1+/+ mice and Cyp1a1–/– mice with MRSA infection. Green indicates increased abundance in the Cyp1a1+/+_MRSA group; red indicates increased abundance in the Cyp1a1–/–_MRSA group. *P < 0.05, **P < 0.01.

Fig 4: Induction of CYP1A1 mRNA by coffee.HepG2 (A), Caco-2 (B), and MCF-7 (C) cells were incubated for 4 h in either PBS or AHS with each sample added as in Fig. 3, except that TCDD was added only at 10-6 M. Error bars indicate SDs for triplicate samples. The mean values for the control cells treated with DMSO in PBS were defined as 1.0. Asterisks indicate statistically significant differences (p<0.05) from the control cells incubated in AHS (arrowheads).

Fig 5: Effect of reox in the presence or absence of the IDO inhibitor 1-MT or the AhR inhibitor CH223191 on AhR level, CYP1A1 expression and ROS generation. (A) AhR protein levels and (B) semi-quantification. (C) CYP1A1 protein levels and (D) semi-quantification. (E) ROS levels. *P<0.05 vs. control; #P<0.05 vs. control with 1-MT; ^P<0.05 vs. control with CH223191; &P<0.05 vs. Reox; @P<0.05 vs. Reox with 1-MT; !P<0.05 vs. Reox with CH223191. 1-MT, 1-DL-methyltryptophan; AhR, aryl-hydrocarbon receptor; CYP1A1, cytochrome P450 family 1 subfamily A polypeptide 1; IDO, indoleamine 2,3-dioxygenase 1; ROS, reactive oxygen species; Reox, reoxygenation.