Ketogenesis mitigates metabolic dysfunction–associated steatotic liver disease through mechanisms that extend beyond fat oxidation
Eric D. Queathem, David B. Stagg, Alisa B. Nelson, Alec B. Chaves, Scott B. Crown, Kyle Fulghum, D. Andre d’Avignon, Justin R. Ryder, Patrick J. Bolan, Abdirahman Hayir, Jacob R. Gillingham, Shannon Jannatpour, Ferrol I. Rome, Ashley S. Williams, Deborah M. Muoio, Sayeed Ikramuddin, Curtis C. Hughey, Patrycja Puchalska, Peter A. Crawford
Eric D. Queathem, David B. Stagg, Alisa B. Nelson, Alec B. Chaves, Scott B. Crown, Kyle Fulghum, D. Andre d’Avignon, Justin R. Ryder, Patrick J. Bolan, Abdirahman Hayir, Jacob R. Gillingham, Shannon Jannatpour, Ferrol I. Rome, Ashley S. Williams, Deborah M. Muoio, Sayeed Ikramuddin, Curtis C. Hughey, Patrycja Puchalska, Peter A. Crawford
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Research Article Hepatology Metabolism

Ketogenesis mitigates metabolic dysfunction–associated steatotic liver disease through mechanisms that extend beyond fat oxidation

Abstract

The progression of metabolic dysfunction–associated steatotic liver disease (MASLD) to metabolic dysfunction–associated steatohepatitis (MASH) involves alterations in both liver-autonomous and systemic metabolism that influence the liver’s balance of fat accretion and disposal. Here, we quantify the contributions of hepatic oxidative pathways to liver injury in MASLD-MASH. Using NMR spectroscopy, UHPLC-MS, and GC-MS, we performed stable isotope tracing and formal flux modeling to quantify hepatic oxidative fluxes in humans across the spectrum of MASLD-MASH, and in mouse models of impaired ketogenesis. In humans with MASH, liver injury correlated positively with ketogenesis and total fat oxidation, but not with turnover of the tricarboxylic acid cycle. Loss-of-function mouse models demonstrated that disruption of mitochondrial HMG-CoA synthase (HMGCS2), the rate-limiting step of ketogenesis, impairs overall hepatic fat oxidation and induces an MASLD-MASH–like phenotype. Disruption of mitochondrial β-hydroxybutyrate dehydrogenase (BDH1), the terminal step of ketogenesis, also impaired fat oxidation, but surprisingly did not exacerbate steatotic liver injury. Taken together, these findings suggest that quantifiable variations in overall hepatic fat oxidation may not be a primary determinant of MASLD-to-MASH progression, but rather that maintenance of ketogenesis could serve a protective role through additional mechanisms that extend beyond overall rates of fat oxidation.

Authors

Eric D. Queathem, David B. Stagg, Alisa B. Nelson, Alec B. Chaves, Scott B. Crown, Kyle Fulghum, D. Andre d’Avignon, Justin R. Ryder, Patrick J. Bolan, Abdirahman Hayir, Jacob R. Gillingham, Shannon Jannatpour, Ferrol I. Rome, Ashley S. Williams, Deborah M. Muoio, Sayeed Ikramuddin, Curtis C. Hughey, Patrycja Puchalska, Peter A. Crawford

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Figure 8

Ketogenic insufficiency impairs fat oxidation in perfused livers.

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Ketogenic insufficiency impairs fat oxidation in perfused livers. (A) Pr...
(A) Prior studies have demonstrated that ketogenesis insufficiency induced by loss of HMGCS2 causes accumulation of mitochondrial acetyl-CoA and acceleration of the TCA cycle. Livers of male mice treated with scrambled control antisense oligonucleotide (ASO) or mouse Hmgcs2 ASO were perfused with octanoate (C8) and oxidative fluxes quantified using 2H/13C stable isotope tracing. (B and C) Total fat oxidation quantified as the summation of (2 × ketogenesis) + TCA cycle turnover (B), and reducing equivalent (RE) turnover (NADH + FADH2) broken down into REs from gluconeogenesis (GNG), β-oxidation, and the TCA cycle (C), in perfused livers from control and Hmgcs2 ASO mice on chow diet (n = 10–11 per group). Fat oxidation was also studied in livers perfused ex vivo with C8 from control and Hmgcs2 ASO–treated mice maintained on a 42% high-fat high-sucrose Western diet (WD) for 8 weeks. (D–F) TCA cycle turnover (D), total fat oxidation (E), and RE production rate (NADH + FADH2) (F) in perfused livers from control and Hmgcs2 ASO–treated mice on WD (n = 5–6 per group). Data are expressed as mean ± SD. Statistical differences were determined by Student’s t tests or 2-way ANOVA and accepted as significant if P < 0.05. *P < 0.05, **P < 0.01, ***P < 0.001.