Fig 2: IL17A and IL22 production are upregulated in the serum of patients with vitiligo. Serum (A) IL17A and (B) IL22 measured by ELISA in peripheral venous blood samples collected from patients with vitiligo (n=20) and healthy controls (n=20). (C) Representative immunohistochemical and (D) quantitative analyses of skin samples from patients with vitiligo (n=20) and healthy controls (n=10). Scale bar = 100 µm. Correlation between serum (E) IL17A levels and AhR mRNA levels in CD4+ T cells and (F) serum IL22 levels and AhR mRNA levels in CD4+ T cells of patients with vitiligo (n=20). *P 0.05, **P<0.01 and ****P<0.0001. IL, interleukin.

Fig 3: AhR activation by Ginkgo biloba extract EGb 761 regulates IL17A and IL22 production in CD4+ T cells of patients with vitiligo. Cells from patients with vitiligo and healthy subjects were treated with EGb 761 or VAF347, with or without CH223191. (A) CYP1A1 and (B) AhR mRNA levels after 6 h of treatment. *P<0.05 and ***P<0.001. (C) IL17A protein levels measured in the culture medium by ELISA after 72 h of treatment. **P<0.01 and ***P<0.001 vs. untreated healthy control; #P<0.05 vs. untreated vitiligo; $P<0.01 vs. EGb 761-treated vitiligo. (D) IL22 protein levels measured in culture medium by ELISA after 72 h of treatment. *P<0.05 and **P<0.01 vs. untreated healthy control; #P<0.001 vs. untreated vitiligo; $P<0.01 vs. EGb 761-treated vitiligo; &P<0.05 vs. EGb 761-treated healthy control. n=3; ns, not significant. AhR, aryl hydrocarbon receptor; CYP1A1, cytochrome P450 1A1; EGb 761, Gingko. biloba extract EGb 761; VAF347, AhR agonist VAF347; CH223191, AhR antagonist CH223191.

Fig 4: AhR knockdown regulates the production of IL17A, but not IL22 in cells of patients with vitiligo. (A) Representative western blot and (B) quantitative analysis of AhR expression in si-control or si-AhR-transfected CD4+ T cells from patients with vitiligo stimulated with anti-CD3 and anti-CD28. (C) IL17A and (D) IL22 levels measured by ELISA after 72 h of transfection. (E) RORC and FoxP3 mRNA levels in si-control or si-AhR-transfected CD4+ T cells of patients with vitiligo after 24 h of transfection. n=3. *P<0.05 and ***P<0.001. AhR, aryl hydrocarbon receptor; si-AhR, small interfering RNA targeting AhR; IL, interleukin; RORC, retinoic acid receptor-related orphan receptor C; ns, not significant.

Fig 5: Expression of IL17 in 2 groups and determination of TP concentration. (A) The percentage of IL-17-positive CD4 + T cells in active AS patients tended to be elevated. (B) PBMC of patients with active AS were treated with different concentrations of TP (12.5–100 μg/mL). IC50 was 73.54 μg/mL for TP. (C) Decreased IL-17 concentration in the supernatant with 25-μg/mL TP; effect on cell proliferation was negligible. One-way ANOVA determined statistical significance. Compared with the blank control group, *: P < .05. PBMCs = Peripheral blood mononuclear cells.