Synergistic hepatotoxicity of azithromycin and acetaminophen involves liver X receptor α-mediated metabolic dysregulation and endoplasmic reticulum stress

Coadministration of azithromycin (AZM) and acetaminophen (APAP) is associated with an increased risk of hepatotoxicity, the underlying mechanism for which remains unclear. Here, we demonstrate that combined AZM and APAP treatment induced liver injury in mice, as evidenced by exacerbated glutathione depletion, enhanced formation of the toxic metabolite, acetaminophen-cysteine, and hepatocellular necrosis. Mechanistically, the combination inhibited liver X receptor α (LXRα) and upregulated pregnane X receptor, leading to increased expression of phase I Enzymes, CYP2E1 and CYP3A11, while downregulating phase II Enzymes, UDP-glucuronosyltransferase 1A and sulfotransferase 2A1. Furthermore, the combined treatment disrupted the LXRα-lysophosphatidylcholine Acyltransferase 3 axis, which acts as a central driver inducing endoplasmic reticulum and oxidative stress, ultimately promoting hepatocyte Apoptosis. Pharmacological activation of LXR (using GW3965, LXR Agonist) or inhibition of pregnane X receptor (using pimecrolimus) conferred significant protection against liver injury. The complete abolition of GW3965-mediated protection in Lxrα-knockout mice unequivocally established the central and obligatory role of LXRα in this synergistic mechanism. Our findings indicate that coadministration of AZM and APAP induces hepatotoxicity through a dual-pronged mechanism involving metabolic dysregulation via the LXRα-cytochrome P450/UDP-glucuronosyltransferase axis and aggravation of endoplasmic reticulum stress via the LXRα-lysophosphatidylcholine Acyltransferase 3 pathway. Collectively, these findings underscore the need for extreme caution in the clinical coprescription of AZM and APAP and highlight LXRα as a potential target for preventing liver injury. SIGNIFICANCE STATEMENT: This study demonstrates that azithromycin synergizes with acetaminophen to induce liver injury by suppressing liver X receptor α (LXRα). This suppression disrupts metabolic balance via the LXRα-cytochrome P450/UDP-glucuronosyltransferase axis and exacerbates endoplasmic reticulum stress via the LXRα-lysophosphatidylcholine Acyltransferase 3 pathway. Based on the finding of a critical drug-drug interaction, the study cautions against coadministration of azithromycin and acetaminophen and proposes LXRα as a promising target for preventing hepatotoxicity.