Fig. 4

Indigo increases intestinal IL-22 and improves intestinal barrier function during HFD. a AhR pathway genes, Ahr and Cyp1a1, mRNA expression in small intestine (n = 5/group). (b, left) Il22 mRNA expression of small bowel whole tissue from HFD-Control and HFD-Indigo mice (n = 4/group). (b, right) IL-22 in small bowel tissue explant with or without IL-1β 40 ng/mL stimulation in HFD-Control and HFD-Indigo wild-type mice (n = 5/group). c Serum IL-22 in HFD-Control and HFD-Indigo mice (n = 4/group). d Plasma FD4 concentration after 4 h following oral gavage in HFD-Control, and HFD-Indigo after 13 weeks of diet (n = 7/group, ^**p = 0.007 Mann–Whitney test). e Serum anti-LPS IgG levels of age-matched HFD-Control and HFD-Indigo mice after 14 weeks HFD (n = 5 in HFD-Control, n = 6 in HFD-Indigo mice). f Reg3g, claudin1, ZO1, and Muc2 mRNA expression of small bowel whole tissue from HFD-Control and HFD-Indigo mice (Reg3g, claudin1: n = 4/group; ZO1, Muc2: n = 5/group). g IL-22 in differentiated IL-22 producing CD4+ T cells from mesenteric lymph nodes of WT HFD mice in vitro treated with DMSO, Indigo 50 μM, and 300 nM FICZ for 4 days (n = 3/group). h Flow cytometry analysis of total ILC3s, ILC3 subsets and their IL-22 secretion in LP of mice after 15 weeks of HFD or HFD-Indigo (300 mg/kg/day) (n = 5 in HFD-Control, n = 4 in HFD-Indigo mice). i, j Body weights (i), GTT (j, left), and ITT (j, right) of Rag1^null mice after 10 weeks of HFD or HFD-Indigo (300 mg/kg/day) (n = 4 in HFD-Control, n = 5 in HFD-Indigo Rag1^null mice). k IL-22 in the small bowel tissue explant culture supernatant of Rag1^null mice fed with HFD for 14 weeks ex vivo stimulated with IL-1β 40 ng/mL and treated with 0.05% DMSO and 50 μM indigo for 24 h (n = 4/group). Data in bar graphs represent mean ± SEM. ^*p < 0.05, ^**p < 0.01