Cytochrome P450 1B1 specifically promotes the differentiation and pathogenicity of pathogenic Th17 cells while not altering the generation of nonpathogenic Th17 cells in mice and humans with colitis.

In inflamed gut tissue, a specific enzyme called CYP1B1 keeps levels of harmful molecules low inside certain immune cells. This allows the mitochondria in those cells to stay healthy and functional, which is required for the cells to become aggressive and cause damage. Without this enzyme, those harmful molecules build up, the mitochondria break down, and the aggressive immune cells cannot form or survive. Other types of immune cells in the same environment are not affected.