Unsaturated fatty acids aggravate mitochondrial dysfunction in senescent primary hepatocytes

Background and Aim Senescence is an irreversible cell cycle arrest caused by cellular stress leading to a senescent phenotype. In pre-clinical models, the steatotic liver shows increased hepatocellular senescence. Oleic acid (OA), a monounsaturated fatty acid (FA), prevents saturated FA-induced lipotoxicity but is implicated in MAFLD development. We hypothesize that senescence hinders oleic acid's beneficial effects via mitochondrial dysfunction.

Methods Primary hepatocytes, isolated from mice, were cultured overnight. Cells were sensitized with senescence inducers H2O2 (oxidative stress) and Nutlin 3a (p53 stabilization) for 24 hours, followed by 24-hour incubation with OA. Steatotic or senescent cells were further treated with senolytics, dasatinib, and quercetin (D+Q) for 24 hours. Neutral lipid was measured by Oil Red-O staining and senescence markers p21, p53, and γH2A.X by immunofluorescence. Mitochondrial function was assessed by XFe Seahorse analyser.

Results 24 hours OA-treatment increased lipid accumulation by 4-fold (p<0.05) and upregulated p53, γH2A.X, and p21 (1.25-fold, p<0.05). While OA enhanced metabolic activity in non-senescent cells, it impaired mitochondrial function in senescent cells (H2O2 or Nutlin 3a-treated). Dasatinib and quercetin treatments (senolytics) were able to recover these effects while p53 could be reduced (p-ns) and fat accumulation remained unchanged. However, pre-senescent D+Q treated hepatocytes have shown reduced fat content along with decreased p53 and γH2A.X.

Conclusion Oleic acid induces senescence in primary hepatocytes and enhances OCR and glycolysis, while senescent cells exhibit the opposite response. This highlights the significance of targeting senescence therapeutically in MAFLD.

Publication History

Article published online:
23 January 2024