Figure 7.

5-Hydroxyindole-3-Acetic Acid Increases Il10 Transcription by B cells In Vivo and In Vitro by Acting as a Ligand for AhR

(A) Relative expression of Cyp1a1 and Il10 in total splenic B cells following 6-h culture with 5-HIAA or kynurenic acid (KYNA) compared to vehicle alone (n = 3, one of two experiments is shown).

(B) Mean clinical score of control, 5-HIAA-gavaged, or KYNA-gavaged mice; y axis shows percentage swelling in antigen-injected knee compared to control knee (cumulative n = 8 per group, one representative experiment of two experiments is shown).

(C) Bar charts show expression of Cyp1a1 and Il10 relative to β-actin in splenic B cells isolated from control, 5-HIAA-gavaged, or KYNA-gavaged mice.

(D) Mean clinical score of control or 5-HIAA-gavaged Mb1^cre/+ mice or Ahr^fl/−Mb1^cre/+ mice; y axis shows percentage swelling in antigen-injected knee compared to control knee (cumulative n = 8 per group, one representative experiment of two experiments is shown).

(E) Mean clinical score of control and butyrate-supplemented L-para-chlorophenylalanine (PCPA)-treated (tryptophanase inhibitor, TPH) or vehicle-treated mice; y axis shows percentage swelling in antigen-injected knee compared to control knee (cumulative n = 10 per group, one representative experiment of two experiments is shown).

Data represent mean ± SE (A, Student’s t test; B, two-way ANOVA; C, one-way ANOVA; D and E, two-way ANOVA).