Itaconate suppresses neonatal intestinal inflammation via metabolic reprogramming of M1 macrophage.

BACKGROUND: Necrotizing enterocolitis (NEC) is a rapidly progressive and severe gastrointestinal disorder in neonates that is marked by an inflammatory cascade initiated by mechanisms that remain incompletely understood, resulting in intestinal necrosis and systemic infections. This study demonstrated that itaconate (ITA) exerts a protective effect in NEC by regulating macrophage reprogramming. METHODS: Changes in ITA expression were investigated using immunofluorescence staining and liquid chromatography-mass spectrometry, and their effect on immune cell differentiation was verified through single-cell sequencing. In vivo experiments were performed using ACOD1(-/-) and ACOD1(fl/fl)LysM(cre) NEC mouse models. RESULTS: We detected changes in ITA expression in clinical NEC samples and confirmed the effect of these changes on immune cell differentiation. In vivo experiments confirmed the therapeutic role of ITA in regulating macrophage differentiation in NEC, and we further investigated the mechanism by which ITA regulates macrophage metabolic reprogramming. The depletion of ITA in NEC correlates with an increased frequency of pro-inflammatory macrophage polarization, thereby exacerbating intestinal inflammatory injury. Importantly, our in vivo experiments revealed that treatment with 4-octyl itaconate (4OI) significantly mitigated intestinal symptoms associated with NEC in murine models. Mechanistic investigations showed that 4OI effectively suppressed M1 macrophage polarization by rescuing mitochondrial function and upregulating oxidative phosphorylation in macrophages. CONCLUSIONS: Our results highlight ITA as a metabolic checkpoint of macrophage differentiation in NEC and suggest the therapeutic efficacy of 4OI in NEC. KEY POINTS: Itaconate alleviates NEC by reprogramming M1 macrophage metabolism ACOD1 deficiency exacerbates NEC severity 4OI maintains intestinal barrier integrity. 4OI rescues NEC by regulating macrophage mitochondrial activity.