Cytochrome P450 isoforms. Regulation during infection, inflammation and by cytokines.

Multiple isoforms of cytochrome P450 (P450) have been discovered that are important biomedically to drug pharmacokinetics, chemical carcinogenesis, and metabolism of endogenous agents such as steroids, arachidonic acids, and prostaglandins. P450 level and activity are altered during infection and inflammation, apparently by cytokines released during activation of the immune system. Cytokines shown to affect P450 are interferon (IFN), interleukin 1 (IL-1), tumor necrosis factor (TNF), and interleukin 6 (IL-6). Understanding the enzymology and regulation of the P450 monooxygenation system in animals and humans may allow more accurate extrapolation of toxicity and cancer data from laboratory animals to clinical medicine as well as more rational selection of therapeutic regimens.