Cholesterol and p53 promote senescence and systemic fibrosis in metabolic dysfunction-associated steatohepatitis

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ABSTRACT Background & aims TP53 (p53) coordinates diverse cellular stress response programmes including pro-survival activities, senescence, and cell death. During tissue damage, p53 can shape both the local cellular response to injury, including the fibrotic response, and influence distal organ biology. Fibrosis in the liver is a major driver of hepatocellular carcinoma (HCC) risk within metabolic dysfunction-associated steatohepatitis (MASH). It is also an important determinant of dysfunction in multiple distal tissues including the kidneys, lungs, and heart. Despite significant clinical burden, our understanding of the molecular determinants of fibrotic MASH and its relationship to multiorgan fibrosis remain incomplete. Here, we investigate local and systemic effects of hepatocellular p53 activity and cholesterol during MASH development, with implications for disease prevention. Methods This study utilised a genetic model of stabilised p53, diet-induced MASH models with varying cholesterol compositions, and an in vitro obesogenic system to investigate p53 activity during liver disease development. Non-invasive imaging and histopathological analyses were employed to monitor p53 activity, MASH, and multiorgan fibrosis in vivo . Complementary approaches, including in vitro human multicomponent liver spheroids, cytokine arrays, and analyses of human MASH transcriptomic and proteomic datasets, were used to examine molecular drivers and patient relevance. Results Using an inducible mouse model of MDM2 E3 ubiquitin ligase deficiency to stabilise p53, we report that hepatocellular MDM2 E3 loss results in progressive fibrotic damage, robust hepatocellular expression of the p53 target gene CDKN1A/p21 (p21),and induces p21 and fibrosis in the kidneys of male mice in a sex-specific manner. In diet-induced MASH, we observe cholesterol and p53-dependent development of liver fibrosis, high expression of hepatocellular p21, and induction of p21 and fibrosis in the kidneys of male mice—reminiscent of features observed in MDM2 E3-deficient mice. We also observe fibrosis in the lungs and heart of male MASH mice. Both a cholesterol-free obesogenic diet and liver-specific loss of p53 mitigate hepatic fibrosis and systemic induction of p21 and fibrosis. Mechanistically, p53 induces hepatic expression of senescence-associated secretory phenotype (SASP) factors, including GDF15, in vivo . A human multicomponent LiverACE spheroid model showed a concordant trend towards increased GDF15 protein abundance under steatotic stress, while in humans, elevated circulating GDF15 levels in advanced MASH correlate with increased TNFRSF1A and EPHA2, circulating markers linked to kidney injury. Conclusions Our work identifies undue p53 activity within the liver as a driver of multiorgan fibrosis in a sex-specific manner, affecting male but not female mice. We implicate cholesterol in promoting this pro-fibrotic environment in vivo and highlight circulating factors that could identify at-risk patients for multiorgan fibrosis in MASH. IMPACT AND IMPLICATIONS P53 is a potent tumour suppressor that is frequently mutated or lost in HCC. Our findings suggest that dietary cholesterol promotes detrimental overactivation of p53 in MASH and facilitates fibrosis within the liver and distal organs. Further studies evaluating the efficacy of targeting hepatic p53 in combination with dietary or weight loss interventions could provide new treatment approaches for systemic fibrosis and MASH.

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