GSE158715
Arylhydrocarbon receptor and the cytochrome P450 enzyme CYP1B1 prevent exacerbation of allergic airway inflammation
Signaling via the arylhydrocarbon receptor (AhR) is thought to contribute to exacerbation of allergic asthma by anthropogenic pollution. The physiological role of AhR and its downstream targets CYP1 family members upon exposure to aeroallergens remain unknown. We seek to characterize the role of the AhR pathway for the regulation of allergic airway inflammation (AAI). We employed knockout animals of the AhR and its downstream target cytochrome P450 enzymes CYP1A1, CYP1A2 and CYP1B1 and subjected them to preclinical allergic asthma models (ragweed and house dust mite) to assess the role of AhR and CYP1 family members in allergic airway inflammation. Histological, transcriptional and functional assays were used to uncover relevant cell types and mechanistic insights. In the ragweed model, AhRKO/KO and CYP1B1KO/KO but not CYP1A2 KO/KO or CYP1A2KO/KO animals showed exacerbation of AAI including elevated infiltration of cells in the bronchoalveolar lavage fluid and increased serum levels of IgE and allergen-specific IgG1. AhR KO/KO and CYP1B1KO/KO animals showed also more severe reactions in HDM-induced allergic AAI. Bone marrow chimeras as well as qPCR analysis and immune fluorescence histology indicate that expression of CYP1B1 in non-hematopoietic cells – presumably lung epithelial cells – is necessary to prevent exacerbation of HDM-induced AAI. Mechanistically, we show that CYP1B1 deficiency leads to enhanced expression and activity of CYP1A1 in lung epithelial cells and thus potentially to deprivation from endogenous AhR ligands. Transcriptional analysis of primary lung epithelial cells indicates a functional link of the AhR to regulation of circadian clock genes at baseline and massive alteration of gene expression upon allergen exposure. Overall design: mRNA profiles of FACS-purified single alive CD45-EpCAM+ lung epithelial cells of wildtype, AhR-KO/KO and CYP1B1-KO/KO mice at steady state or after houst dust mite allergy