Sex-specific mitochondrial dysregulation and metformin response in Wilson disease

Wilson disease (WD) is an inherited disorder of copper metabolism characterized by hepatic copper accumulation, mitochondrial injury, and systemic metabolic dysfunction. Metformin is a widely used antihyperglycemic agent with known effects on mitochondrial metabolism and cellular redox state. We tested whether metformin modifies hepatic mitochondrial abnormalities in a mouse model of WD, stratified by sex. Adult male and female Atp7b^-/- mice were treated with metformin in drinking water (500 mg/kg/day) or water alone for 2 weeks. Liver mitochondria were evaluated by transmission electron microscopy and quantitative morphometry, respiratory chain enzyme activities, reactive oxygen species production, hepatic and mitochondrial copper and iron content, and targeted glucocorticoid and bile acid profiling. At baseline, female Atp7b^-/- mice exhibited greater mitochondrial ultrastructural injury, smaller mitochondrial size, and higher hepatic and mitochondrial copper and iron levels compared with males. Metformin exposure was higher in females and was associated with marked changes in mitochondrial morphology, including increased size and more regularized structural features, along with alterations in respiratory enzyme activities, reduced oxidative stress, and changes in glucocorticoid and bile acid profiles. In contrast, males showed more limited structural and biochemical changes following treatment. These findings identify sex as an important determinant of mitochondrial phenotype and response to metformin in WD and support further investigation of sex-informed therapeutic strategies.