Copper's dual role: Reviewing its impact on liver health and disease

As an essential trace element in the human body, Cu exists in the oxidation states of Cu(II) and Cu(I). The interconversion between these states is closely associated with various redox reactions and plays a pivotal role in cellular respiration regulation, energy metabolism, cell growth regulation, and angiogenesis promotion among other biological processes. As the primary metabolic organ, the liver synthesises and secretes Cu-binding proteins to maintain Cu homeostasis and regulate its metabolism. Studies have increasingly demonstrated that abnormally high or low levels of Cu can negatively affect the immune and metabolic microenvironment within the liver. In this review, we summarise the mechanisms underlying Cu metabolism and its dysregulation and highlight the potential involvement of disrupted Cu metabolism in several liver diseases. Our review provides insights that will help in the future development of novel therapeutic targets focusing on Cu metabolism.