Extracellular vesicles from maternal uterine cells exposed to risk factors cause fetal inflammatory response.

Fetal cell-derived exosomes (extracellular vesicles, 40-160 nm) are communication channels that can signal parturition by inducing inflammatory changes in maternal decidua and myometrium. Little is known about maternal cell-derived exosomes and their functional roles on the fetal side. This study isolated and characterized exosomes from decidual and myometrial cells grown under normal and inflammatory/oxidative stress conditions and determined their impact on fetal membrane cells. Decidual and myometrial cells were grown under standard culture conditions (control) or exposed for 48 h to cigarette smoke extract or tumor necrosis factor-α, as proxies for oxidative stress and inflammation, respectively. Exosomes were isolated from media (differential ultra-centrifugation followed by size exclusion chromatography), quantified (nano particle tracking analysis), and characterized in terms of their size and morphology (cryo-electron microscopy), markers (dot blot), and cargo contents (proteomics followed by bioinformatics analysis). Maternal exosomes (109/mL) were used to treat amnion epithelial cells and chorion trophoblast cells for 24 h. The exosome uptake by fetal cells (confocal microscopy) and the cytokine response (enzyme-linked immunosorbent assays for IL-6, IL-10, and TNF-α) was determined. Exosomes from both decidual and myometrial cells were round and expressed tetraspanins and endosomal sorting complexes required for transport (ESCRT) protein markers. The size and quantity was not different between control and treated cell exosomes. Proteomic analysis identified several common proteins in exosomes, as well as unique proteins based on cell type and treatment. Compared to control exosomes, pro-inflammatory cytokine release was higher in both amnion epithelial cell and chorion trophoblast cell media when the cells had been exposed to exosomes from decidual or myometrial cells treated with either cigarette smoke extract or tumor necrosis factor-α. In chorion trophoblast cells, anti-inflammatory IL-10 was increased by exosomes from both decidual and myometrial cells. Various pathophysiological conditions cause maternal exosomes to carry inflammatory mediators that can result in cell type dependent fetal inflammatory response. Video Abstract.