Hepatotoxicity Mechanisms of Sirolimus and Everolimus Unveiled Through Metabolomics and Transcriptomics Analysis.

Sirolimus and everolimus, two representative inhibitors of the mammalian target of rapamycin (mTOR), have distinct therapeutic effects on numerous paediatric diseases that do not have specific treatments, particularly vascular abnormalities, but their safety regarding the growth and development of children is still worth considering. The most frequent adverse reaction in clinical practice, elevated liver enzymes, has not yet been thoroughly investigated to determine whether it is hepatotoxic to growth and development. In this study, experiments with zebrafish models revealed that sirolimus and everolimus caused hepatotoxicity, on the basis of the delayed rate of yolk sac absorption, even at a standard dose (≤ 0.1 μM). At high concentrations (≥ 0.5 μM), more pronounced hepatotoxic effects were observed, including significant reductions in liver size, elevated ALT levels, widened gaps between hepatocytes and increased vacuolization within hepatocytes, as assessed by liver morphology, functional biomarkers and histopathology. Integrated transcriptomic and metabolomic analyses revealed that the hepatotoxicity was associated with aberrant activation of the PI3K/AKT pathway and disrupted lipid metabolism, primarily driven by downregulation of phosphoenolpyruvate carboxykinase 1 (PCK1). These findings underscore the importance of regular monitoring of drug blood concentrations in paediatric patients and provide new insights into dose optimization and toxicity surveillance in children.