Fig. 1: Induction of IEC IDO by HFD has a protective role in atherosclerosis.

A Tryptophan (Trp), Kynurenine (Kyn) levels, and related Kyn/Trp ratio (%) in the small intestine extracts (n = 5 mice/group), B plasma indole levels in the portal vein, C. 5-hydroxytryptamine (5-HT) in the small intestine extracts of male Ldlr^−/− mice fed either normal chow diet (NCD), high-fat diet (HFD), or high-cholesterol diet (HCD) or the combination of both HFD + HCD for 13 weeks (n = 5 mice/group). D Kyn levels in feces of Ldlr^−/− mice fed HFD supplemented or not with FOS for 13 weeks (n = 5 mice/group). E, F Kyn/Trp ratio (%) in the small intestine extracts and plasma in male Ldlr^−/− IEC IDO KO and littermate control Ldlr^−/− IEC IDO mice (n = 5 mice/group), after 8 weeks of HFD + HCD or NCD feeding period. NCD represents the control group without atherosclerosis development. G. Plasma cholesterol, H representative pictures, and quantifications of plaque size in the aortic sinus in male Ldlr^−/− IEC IDO KO (n = 12 mice) and littermate control Ldlr^−/− IEC IDO (n = 12 mice) fed HFD + HCD for 8 weeks; scale bar 200 µm. I Plasma cholesterol, J representative pictures and quantifications of plaque size in the aortic sinus in female Ldlr^−/− IEC IDO KO (n = 9 mice), and littermate controls Ldlr^−/− IEC IDO (n = 9 mice) fed HFD + HCD for 13 weeks; scale bar 200 µm. Individual data are presented as scattered dot plots, with the mean and s.e.m. The p values were determined using the Brown-Forsythe one-way ANOVA test followed by Tukey’s multiple comparison test. Source data are provided as a Source Data file.