Loss of immunometabolic adaptability in MASH: gut-derived signals drive macrophage reprogramming and fibrosis.

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive inflammatory subtype of metabolic dysfunction-associated steatotic liver disease (MASLD), characterized by hepatocellular steatosis, persistent inflammation, and varying degrees of fibrosis. Although multiple therapeutic strategies targeting inflammatory or metabolic pathways have entered clinical development, their overall efficacy remains limited, suggesting that the mechanisms driving sustained disease progression remain incompletely understood. Previous studies have largely focused on inflammatory cascades, whereas the role of immune cell energy metabolism in sustaining inflammation and promoting fibrosis has received comparatively less attention. Recent work has increasingly shifted toward immunometabolic reprogramming, indicating that metabolic signals derived from the gut microbiota may contribute to the establishment and maintenance of the hepatic immune microenvironment. In this context, reductions in short-chain fatty acids and secondary bile acids, together with increased succinate and endotoxin levels, may alter the energy metabolism of Kupffer cells and infiltrating macrophages through signaling pathways involving FXR/TGR5 and mTOR/AMPK, thereby favoring a pro-inflammatory phenotype. This metabolic shift is associated with enhanced inflammatory signaling linked to HIF-1α, increased NLRP3 inflammasome activity, and paracrine effects that may promote hepatic stellate cell activation during fibrotic progression. Overall, current evidence supports a model in which MASH progression is associated with a gradual loss of immunometabolic adaptability in the setting of metabolic dysregulation along the gut-liver axis. Reduced metabolic flexibility may limit the ability of immune cells to transition between functional states, thereby hindering resolution of inflammation and contributing to pathological tissue remodeling. Within this framework, single-target interventions may be insufficient to fully restore immunometabolic homeostasis, whereas strategies that concurrently address gut microbial function and key metabolic signaling pathways may be more mechanistically sound. Considering MASH as a model of systemic immunometabolic dysregulation may also provide insight into other metabolism-associated inflammatory diseases, although extrapolation should remain cautious.