Aberrant interferon-γ signaling disrupts trophoblast invasion via IDO1/AHR signaling and metabolic reprogramming associated with recurrent pregnancy loss

AIMS: Recurrent pregnancy loss (RPL) is a multifactorial reproductive disorder in which immune dysregulation has been increasingly implicated. This study aimed to elucidate how interferon-γ (IFN-γ) signaling affects trophoblast function and metabolism and to explore the underlying immunometabolic mechanisms contributing to RPL pathogenesis. MATERIALS AND METHODS: Human trophoblast cells were treated with IFN-γ to assess proliferation, apoptosis, migration, and invasion. Metabolic alterations were analyzed using Seahorse extracellular flux assays, glucose uptake measurements, and metabolomic profiling. Molecular mechanisms were investigated by examining IDO1 expression, kynurenine production, aryl hydrocarbon receptor (AHR) activation, and hypoxia-inducible factor-1α (HIF-1α) signaling. IDO1 expression was further evaluated in chorionic villi from RPL patients and healthy controls. KEY FINDINGS: IFN-γ selectively suppressed trophoblast migration and invasion without affecting proliferation or apoptosis. IFN-γ markedly upregulated IDO1, leading to increased kynurenine accumulation and activation of AHR signaling through nuclear translocation and ARNT dimerization, thereby shifting trophoblasts toward an epithelial-like phenotype. Concurrently, IFN-γ stabilized HIF-1α and enhanced glycolytic flux, glucose uptake, and lactate secretion, accompanied by reduced tricarboxylic acid cycle intermediates. Pharmacological inhibition of glycolysis with 2-DG attenuated IFN-γ-induced IDO1 expression in a dose-dependent manner. Aberrant IDO1 expression was also observed in chorionic villi from RPL patients. SIGNIFICANCE: These findings demonstrate that IFN-γ signaling impairs trophoblast invasion through coordinated activation of the IDO1/kynurenine/AHR axis and metabolic reprogramming, revealing an immunometabolic mechanism that may contribute to the pathogenesis of recurrent pregnancy loss.