Targeting Xenobiotic Nuclear Receptors PXR and CAR to Prevent Cobicistat Hepatotoxicity

Liver-related diseases including drug-induced liver injury are becoming increasingly prominent in AIDS patients. Cobicistat (COBI) is the backbone of multiple regimens for antiretroviral therapy. The current work investigated the mechanisms of adverse drug-drug interactions associated with COBI that lead to liver damage. For individuals co-infected with HIV and tuberculosis (TB), the World Health Organization recommends the initiation of TB treatment followed by antiretroviral therapy. Rifampicin (RIF), a first line anti-TB drug, is a human specific activator of pregnane X receptor (PXR). Using PXR-humanized mice, we found that RIF-mediated PXR activation potentiates COBI hepatotoxicity. In contrast, rifabutin, a PXR-neutral analog of RIF, has no impact on COBI hepatotoxicity. Because of the crosstalk between PXR and the constitutive androstane receptor (CAR), the role of CAR in COBI hepatotoxicity was also investigated. Similar to PXR, ligand-dependent activation of CAR also potentiates COBI hepatotoxicity. Our further studies illustrated that PXR and CAR modulate COBI hepatotoxicity through the CYP3A4-dependent pathways. In summary, the current work determined PXR and CAR as key modulators of COBI hepatotoxicity. Given the fact that many prescription drugs and herbal supplements can activate PXR and CAR, these two receptors should be considered as targets to prevent COBI hepatotoxicity in the clinic.