Circulating mitochondrial bioenergetics as fingerprint of the hepatic one: how to monitor genetic MASLD

Background & AimsMetabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) pathogenesis is shaped by genetics and mitochondrial dysfunction. Recently, we demonstrated that the co-presence of patatin- like phospholipase domain-containing 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2) and membrane bound o-acyltransferase domain-containing 7 (MBOAT7) polymorphisms predisposes to disease progression in MASLD patients and that their deletion contributes to mitochondrial (mt) maladaptation in an in- vitro model. In this work we deepened the impact of genes silencing on mitochondrial dynamism. Then we restored TM6SF2 and/or MBOAT7 wild-type (WT) proteins in the in-vitro model to evaluate the rescue of organelles morphology/function. Finally, we compared hepatic and peripheral mt-bioenrgetics in MASLD patients carrying PNPLA3, MBOAT7 and/or TM6SF2 loss-of-function variations. MethodsWT proteins were overexpressed through lentiviral transfection, mt-respiration was assessed by Seahorse. ResultsThe restore of MBOAT7 and/or TM6SF2 wild-type proteins resulted in the assembly of spaghetti- shaped mitochondria with improved OXPHOS capacity. Mitochondrial activity was assessed in liver biopsies and peripheral blood mononuclear cells of biopsy-proven (n=44;Discovery cohort) and noninvasively assessed (n=45;Fibroscan-MASLD cohort) MASLD patients stratified according to the presence of the 3 at-risk variants alongside in unrelated liver disease patients (n=45;Unrelated liver disease cohort). In the Discovery cohort, the hepatic bioenergetic profile fully reflecting the circulating one, was impaired in carriers of the risk variants, more so when in combination. We confirmed the lowered serum respirometry in the Fibroscan-MASLD cohort. Finally, the circulating respiration did not change in unrelated liver disease patients, thus demonstrating that it was specifically impaired in MASLD. ConclusionsThese results boosted the relevance of mitochondrial circulating respirometry to outline genetically-based MASLD.