Copper oxide nanoparticles induce non-alcoholic fatty liver disease by disrupting bile acid homeostasis and perturbing the intestinal microbial homeostasis.

The wide application of copper oxide nanoparticles (CuO NPs) in various fields such as medicine, food, agriculture, and animal husbandry can result in direct or indirect oral exposure of CuO NPs to the human body. Therefore, the research on the biosafety of CuO NPs is crucially important. However, previous research mainly concentrated on CuO NPs-induced oxidative stress, rather than the dysregulation of metabolic homeostasis. Our current finding indicates that CuO NPs can enter the systemic circulation and accumulate in the liver by being adopted by the colon and disrupting the intestinal barrier. Subsequently, CuO NPs can impair bile acid (BA) homeostasis through increased reabsorption of bile acids (BAs), ultimately leading to non-alcoholic fatty liver disease (NAFLD). Additionally, the direct stimulation from CuO NPs, damage to the gut barrier, and disruption of BA homeostasis can also disrupt microbial homeostasis in the intestines, including alterations in the composition and biological functions of gut microbiota, thereby triggering NAFLD. These findings deepen our understanding of the biosafety of CuO NPs and provide evidence for their role in disrupting physiological homeostasis.