Figure 6: Inhibition of CYP1 activity amplifies CYP1A1, c-Kit and IL-22 in purified human CD4⁺ T cells.

Human purified and activated CD4⁺ Th cells were treated with the AHR agonist FICZ (0.5 nM) alone or in the presence of the CYP1 inhibitor 1-PP (1 μM) and the AHR antagonist CH-223191 (3 μM) for 4 days. Relative transcription levels of (a) CYP1A1 and (b) AHR in CD4⁺ Th cells. RNA expression levels were analyzed by qRT-PCR. Expression values (C_t values) were normalized by the housekeeping gene EF1A and related to the target gene expression in the medium control (ΔΔC_t). Data were expressed as 2^−(ΔΔCt) indicating relative fold regulations. (c) Induction of the cytokine IL-22 in CD4⁺ Th cells. (d–f) Percentages of CD4⁺c-Kit⁺, CD4⁺IL-22⁺ and CD4⁺c-Kit⁺IL-22⁺ Th cells determined by flow cytometry upon PMA/ionomycin treatment for 5 h. (g) Dot plots of treated CD4⁺ Th cells are representative for four different subjects. Shown are means ± s.e.m. (*p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 by paired t-test).