Indole-3-Lactic Acid Inhibits Doxorubicin-Induced Ferroptosis Through Activating Aryl Hydrocarbon Receptor/Nrf2 Signalling Pathway

The clinical application of doxorubicin (DOX) is limited due to its cardiotoxicity, which is primarily attributed to its interaction with iron in mitochondria, leading to lipid peroxidation and myocardial ferroptosis. This study aimed to investigate the role of the gut microbiota-derived metabolite, indole-3-lactic acid (ILA), in mitigating DOX-induced cardiotoxicity (DIC). Cardiac function, pathological changes, and myocardial ferroptosis were assessed in vivo. The cardioprotective effects and mechanisms of ILA were explored using multi-omics approaches, including single-nucleus RNA sequencing (snRNA-seq) and bulk RNA-seq, and were further validated in Nrf2 knockout mice. The findings revealed that DOX treatment disrupted gut microbiota, significantly reducing the levels of the tryptophan metabolite ILA. In DIC models, ILA supplementation markedly improved cardiac function, reduced collagen deposition, and mitigated cardiac atrophy. The bulk and snRNA-seq analyses indicated that myocardial ferroptosis played a crucial role in the cardioprotective effects of ILA. Experimental data demonstrated that ILA decreased DOX-induced ferroptosis in both DIC mice and DOX-treated H9C2 cells, evidenced by restoration of GPX4 and SLC7A11 levels and reduction of ACSL4. Mechanistically, ILA functions as a ligand for the aryl hydrocarbon receptor (AhR), leading to the upregulation of Nrf2 expression. The protective effects of ILA against ferroptosis were abolished by silencing AhR. Moreover, the beneficial effects of ILA on DIC were eliminated in Nrf2-deficient mice. In conclusion, ILA exerts therapeutic effects against DIC by inhibiting ferroptosis through activation of the AhR/Nrf2 signalling pathway. Identifying the cardioprotective role of the microbial metabolite ILA could offer viable therapeutic strategies for DIC.