Fig. 6: IDO1⁺ Paneth cells are present in intestinal crypts and reduced in Ifngr1^−/− mice.

a qPCR for Ido1 mRNA expression in isolated intestinal epithelial cells of Stat1^flox/flox Apc^Min (si: n = 4; colon: n = 5) and Stat1^∆IEC Apc^Min (si: n = 6; colon: n = 5) mice. b IHC staining for IDO1 (upper images) and double ISH for Ido1 and Lgr5 (lower images) in the small intestine of Stat1^flox/flox Apc^Min and Stat1^∆IEC Apc^Min mice. IDO1⁺ Paneth cells are indicated by arrowheads. Scale bars indicate 20 µm. c–e Quantification of IDO1⁺ crypts (c), LYZ1⁺ Paneth cells/crypt (d), and IDO1⁺ cells/crypt (e) in different intestinal compartments of co-housed Stat1^flox/flox Apc^Min (n = 4), Stat1^∆IEC Apc^Min (n = 5), Stat1^flox/flox (n = 4), Stat1^∆IEC (n = 4), as well as C57BL/6 mice kept at an extra clean SPF facility with and without ABx treatment (n = 3 each). f qPCR for Ido1 mRNA expression after IFNγ stimulation in intestinal organoids of Stat1^flox/flox (three technical replicates, two mice) and Stat1^∆IEC (three technical replicates, three mice) mice. g IF showing the induction of IDO1 upon IFNγ stimulation in tumor organoids of Stat1^flox/flox Apc^Min mice. Scale bars indicate 50 µm. h–j Quantification of IDO1⁺ crypts (h), LYZ1⁺ Paneth cells/crypt (i), and IDO1⁺ cells/crypt (j) in different intestinal compartments of co-housed C57BL/6 (n = 3) and Ifngr1^−/− mice (n = 3). n.d.: not detectable; si: small intestine; SPF: special pathogen free; ABx: antibiotics. Bars represent mean ±  SEM.