Visualization of Dynamic Changes in Labile Iron(II) Pools in Endoplasmic Reticulum Stress-Mediated Drug-Induced Liver Injury

Drug-induced liver injury (DILI) can cause liver failure and even death in severe cases, gravely threatening human health. The treatment of DILI remains a clinical challenge, mainly due to the lack of efficient and accurate diagnosis. Therefore, developing an accurate diagnosis approach is imperative to boost the timely treatment for DILI. As the primary organ of iron storage, liver's functions are tightly linked to iron homeostasis. Thus, monitoring iron homeostasis is promising for the diagnosis and treatment of DILI. Hence, we reported a new near-infrared fluorescent probe (LCy7) that enables real-time and in vivo visualizing of Fe2+ in drug-induced liver injury. In this design, Fe2+ would bind to the N4O ligand in LCy7 and conduce to the C-O bond broken in the presence of O-2, which restore the masked QCy7 emitting luminous near-infrared fluorescence. Utilizing LCy7, the increase in Fe2+ was distinctly witnessed in hepatocytes under endoplasmic reticulum stress by acetaminophen (APAP) stimulation. In vivo near-infrared fluorescence imaging revealed the conspicuous rise in Fe2+ in the liver of mice during APAP-induced liver injury. We further unprecedentedly disclosed that endoplasmic reticulum stress was accompanied by the overload of Fe2+ in injured liver of these mice. Collectively, this work will facilitate a greater understanding of the pathogenesis of DILI, and also provide a powerful new tool for DILI diagnosis and treatment.