SummaryMonocytes (Mos) are crucial in the evolution of metabolic dysfunction-associated steatotic liver disease (MASLD) to metabolic dysfunction-associated steatohepatitis (MASH),and immunometabolism studies have recently suggested targeting leukocyte bioenergetics in inflammatory diseases. Here,we reveal a peculiar bioenergetic phenotype in circulating Mos of patients with MASH,characterized by high levels of glycolysis and mitochondrial (mt) respiration. The enhancement of mt respiratory chain activity,especially complex II (succinate dehydrogenase [SDH]),is unbalanced toward the production of reactive oxygen species (ROS) and is sustained at the transcriptional level with the involvement of the AMPK-mTOR-PGC-1α axis. The modulation of mt activity with dimethyl malonate (DMM),an SDH inhibitor,restores the metabolic profile and almost abrogates cytokine production. Analysis of a public single-cell RNA sequencing (scRNA-seq) dataset confirms that in murine models of MASH,liver Mo-derived macrophages exhibit an upregulation of mt and glycolytic energy pathways. Accordingly,the DMM injection in MASH mice contrasts Mo infiltration and macrophagic enrichment,suggesting immunometabolism as a potential target in MASH. Graphical abstract Highlights•Circulating monocytes (Mos) in patients with MASH show a bioenergetic reprogramming•SDH inhibition in vitro restores MASH Mo bioenergetics,abolishing cytokine production•In mice,energy pathways are upregulated in liver Mo-derived macrophages during MASH•SDH inhibition in vivo reduces Mo infiltration and differentiation in MASH Sangineto et al. investigate the bioenergetics and mitochondrial activity of circulating monocytes in patients with MASH,revealing a hypermetabolic state also identified in liver monocyte-derived macrophages through transcriptomic analysis. Immunometabolic modulation via SDH inhibition attenuates inflammation both in vitro and in vivo,ameliorating MASH.
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