Cyp11a1, a cytochrome P450 enzyme, is the first and rate-limiting enzyme in the steroidogenic pathway, converting cholesterol to pregnenolone.Cyp11a1 expression is increases in activated T cells.
To determine the role of Cyp11a1 activation in the development of peanut allergy and T helper cell functional differentiation.
A Cyp11a1 inhibitor, aminoglutethimide (AMG), was administered to peanut-sensitized and -challenged mice. Clinical symptoms, intestinal inflammation, and Cyp11a1 levels were assessed. The effects of Cyp11a1 inhibition on Th1, Th2, and Th17 differentiation were determined. Cyp11a1 gene silencing was performed using Cyp11a1-targeted short hairpin RNA.
Peanut sensitization and challenge resulted in diarrhea, inflammation and increased levels of Cyp11a1, IL-13, and IL-17A mRNA in the small intestine. Inhibition of Cyp11a1 with AMG prevented allergic diarrhea and inflammation. Levels of pregnenolone in serum were reduced in parallel. AMG-treatment decreased IL13 and IL17A mRNA expression in the small intestine without impacting Cyp11a1 mRNA or protein levels. In vitro, the inhibitor decreased levels of IL13 and IL17A mRNA and protein in differentiated Th2 and Th17 CD4 T cells, respectively, without affecting GATA3, RORγt or Th1 cells and IFNG and T-bet expression. shRNA-mediated silencing of Cyp11a1 in polarized Th2 CD4 T cells significantly decreased levels of pregnenolone, and IL13 mRNA and protein.
Cyp11a1 plays an important role in the development of peanut allergy, regulating peanut allergic responses through effects on steroidogenesis, an essential pathway in Th2 differentiation. Cyp11a1 thus serves as a novel target in the regulation and treatment of peanut allergy.