A copper-deficient diet increases the development of hepatic steatosis, oxidative stress, and mitochondrial dysfunction in mice fed a high-fat diet.

Metabolic and steatotic liver disease (MASLD) is the most prevalent chronic liver disease worldwide and is strongly associated with obesity, insulin resistance, oxidative stress, and mitochondrial dysfunction. Copper, an essential cofactor for enzymes involved in antioxidant defense and mitochondrial oxidative phosphorylation, is frequently depleted in patients with MASLD. Therefore, copper deficiency could exacerbate oxidative stress, inflammation, mitochondrial dysfunction, and hepatocellular damage. The objective of this study was to investigate the impact of dietary copper deficiency on oxidative stress, the inflammatory response, mitochondrial dysfunction, and histopathological changes in mice fed a high-fat diet. Thirty-two male C57BL/6j mice were assigned to four experimental groups: control diet [CD(CU +)], copper-deficient control diet [CD(CU-)], high-fat diet [HFD(CU +)], and copper-deficient high-fat diet [HFD(CU-)] for 12 weeks. Biochemical, histological, inflammatory, oxidative, and mitochondrial parameters were evaluated. Mice in the [HFD(CU-)] group exhibited greater dyslipidemia, elevated transaminases, increased hepatic lipid accumulation, and increased oxidative stress (decreased SOD1 activity, increased TBARS and carbonylated proteins, and decreased reduced GSH), as well as higher levels of proinflammatory cytokines (TNF-α and IL-1β) compared to the [HFD(CU +)] group. Furthermore, the [HFD(CU-)] animals exhibited mitochondrial dysfunction characterized by decreased citrate synthase and complex IV activity and lower PGC1α expression. Histological analysis showed macrovesicular lipid accumulation in 32.8 % of hepatocytes in [HFD(CU-)] mice. Dietary copper restriction (0.66 mg Cu/kg) combined with a high-fat diet decreased SOD1 activity, depleted hepatic GSH, inhibited mitochondrial Complex IV, and increased plasma TNF- α and IL-1β.