Abstract
Co-therapy with rifampicin (RIF) and isoniazid (INH) used to treat tuberculosis in humans frequently causes liver injury. Here, using a pregnane X receptor (PXR)-humanized mouse model, we found that co-treatment with RIF and INH causes accumulation of the endogenous hepatotoxin protoporphyrin IX in the liver through PXR-mediated alteration of the heme biosynthesis pathway. These results provide insight into the mechanism of liver injury induced by co-treatment with these compounds and may lead to their safer use in the clinic.