Background: Periodontitis is increasingly recognised as a significant risk factor for adverse pregnancy outcomes (APOs), yet the mechanisms by which oral pathogens trigger placental dysfunction remain unclear. Porphyromonas gingivalis (Pg), a keystone periodontal pathogen, secretes outer membrane vesicles (Pg-OMVs) that carry virulence factors and can reach distant organs. However, the impact of Pg-OMVs on placental trophoblasts and the accompanying metabolic disturbances is poorly understood. This study investigated the effects of Pg-OMVs on trophoblast function and metabolism. Methods: Pg-OMVs were isolated from Pg cultures. Pregnant mice were exposed to Pg-OMVs in vivo, and placental and uterine weights were recorded. Human trophoblast cells were treated with Pg-OMV in vitro. Untargeted metabolomic profiling of placental tissues was conducted using liquid chromatography–mass spectrometry. Fatty acid β-oxidation (FAO) activity, CD36 expression, and mitochondrial integrity were assessed via enzymatic assays, immunoblotting, transmission electron microscopy, mitochondrial membrane potential measurements, and oxygen consumption rate analysis. Results: Pg-OMVs were internalised by placental trophoblasts, and their presence was associated with significantly reduced placental and uterine weights. Metabolomics revealed a marked accumulation of long-chain acylcarnitines, particularly C20:1 carnitine, indicating impaired FAO. Pg-OMV exposure suppressed FAO activity, downregulated the fatty acid translocase CD36, and induced severe mitochondrial dysfunction, evidenced by cristae loss, decreased mitochondrial membrane potential, and diminished oxygen consumption rates. Conclusions: Pg-OMV compromise placental integrity by disrupting mitochondrial fatty acid β-oxidation, providing a novel mechanistic link between periodontal pathogen-derived vesicles and the pathogenesis of APOs.
Wang et al. (Tue,) studied this question.