Reprogramming offspring liver health: maternal indole supplementation as a preventive strategy against MASLD

BACKGROUND: Disruptions in early-life gut microbiota and metabolites associated with maternal Western-style diet (WD) during critical windows of development are linked to metabolic and inflammatory diseases in offspring, including metabolic dysfunction-associated steatotic liver disease (MASLD) in later life. These disturbances can alter microbial metabolite production, such as tryptophan derivatives, which are crucial for immune and metabolic regulation. However, the specific effects of maternal supplementation with tryptophan metabolites on offspring gut microbiome maturation and MASLD risk remain unexplored. METHODS: WD-fed mouse dams were supplemented with microbial metabolites indole (Ind) or indole-3-acetic acid (I3A) during gestation and lactation; male offspring were weaned to chow diet for 9 weeks, followed by a 4-week WD challenge. Fecal microbiota transfer (FMT) was performed from offspring to naïve recipients, followed by a 4-week WD challenge. Human LX-2 stellate cells were used to study mechanisms for indole and very long-chain (VLC) ceramide effects on TGF-β-induced fibrosis. FINDINGS: Maternal supplementation with Ind or I3A had long-term protective effects in adult WD-challenged offspring against excess weight gain, steatosis, stellate cell activation, and fibrosis. Perinatal exposure to Ind or I3A activated offspring aryl hydrocarbon receptor (AHR) signalling in gut and liver, which trans-repressed known and new target genes, including ceramidases Asah2 and Acer3, leading to increased VLC ceramides. FMT from offspring with perinatal exposure to Ind protected recipients from WD-induced fibrogenesis and increased beneficial VLC ceramides in recipient livers. In vitro, LX-2 stellate cells cultured with Ind or VLC ceramides demonstrated an anti-fibrotic effect, which was abolished by AHR inhibition. INTERPRETATION: Maternal indole supplementation, through sustained activation of AHR in offspring gut and liver and an increase in hepatic VLC ceramides, prevents diet-induced MASLD and fibrosis in offspring, offering a novel therapeutic pathway for prevention of paediatric MASLD. FUNDING: See Acknowledgements.