Figure 7.

Bile contains high levels of retinol and imprints bone marrow-derived dendritic cells (BM-DCs) with the ability to generate CC chemokine (CCR)9⁺ T cells. (a) Luciferase expression in small intestinal lamina propria (SI-LP) and colonic CD103⁺ DCs from DR5 mice kept on a 4-week vitamin A-deficient (VAD) or control diet. Results are the mean (s.d.) of 3 (4-week VAD) or 2 (control diet) independent experiments using pooled SI-LP CD103⁺ DCs from 2 mice per experiment, or from 1 experiment using pooled colonic CD103⁺ DCs from 3 mice. (b) Bile and serum retinol levels in control and 4-week VAD mice. Mean (s.d.) of 7–12 individual mice (serum) or from 7–12 samples from 1–3 pooled mice per sample (bile). (c) BM-DCs from DR5 mice were incubated for 2 days with retinoic acid (RA) (20 n) or bile (0.5%) with/without the pan RA receptor inhibitor (inh) LE540 (2 μ). Luciferase activity/10⁵ MHCII⁺ CD11c⁺ cells was determined and normalized in each experiment to the control. Each symbol represents a single experiment with separate bile samples per experiment. (d) Aldehyde dehydrogenase activity and (e) aldh1a2 expression in CD11c⁺MHCII^int BM-DCs after treatment with the indicated compounds. (d) Each symbol represents data obtained from individual wells in which BM-DCs were incubated with bile samples from different mice. Data are mean (s.d.) of four to six independent experiments. (f) BM-DCs were incubated with bile (0.5%) in the presence or absence of RAR inhibitor (inh) for 2 days, washed, pulsed with ovalbumin (OVA), and incubated together with OT-I cells. CCR9 expression on responding cells was assessed 3.5 days later by flow cytometry. Each symbol represents data from individual wells in which BM-DCs were pre-incubated with bile samples obtained from different mice. Mean (s.d.) of two to three experiments. n.s., not significant.