Exploring multiorgan mitochondrial dysfunction in the switch toward progressive MASLD in AMLN mice

Hepatic mitochondrial maladaptation features the transition from metabolic dysfunction-associated steatotic liver disease (MASLD) to Steatohepatitis (MASH) up to fibrosis/cirrhosis. However, it is still unexplored whether mitochondrial alterations also affect adipose tissue, muscle and heart during disease progression. C57Bl/6 mice were fed an AMLN diet to recapitulate the human MASLD spectrum. In the liver, TEM depicted a progressive morphologic dysfunction of mitochondria, which appeared swollen in MASH, with disorganized cristae/matrix loss in MASH-fibrosis. The mitophagy pathway was reduced in MASH-fibrosis, thus explaining the accumulation of damaged mitochondria, whereas mitochondrial complexes activities alongside OXPHOS protein levels and ATP production were dampened across the disease in liver, adipose, muscle, and cardiac tissues. Finally, the release of cell-free circulating mitochondrial DNA into the bloodstream reflected tissue mitochondrial impairment. In sum, we demonstrated that alterations in mitochondrial morphology, life cycle, and activity feature all disease stages in the liver but also in other tissues engaged in MASLD evolution.