Alterations in the pro-resolving lipid mediator machinery within first trimester maternal tissue: Implications in decidualization and miscarriage risk.

A pivotal event in uterine receptivity and human reproduction is the differentiation of endometrial stromal cells into decidual cells, known as decidualization. Decidualization is interlinked with its inflammatory environment. Our study aimed to investigate the presence and role of pro-resolving lipid mediators in first trimester maternal tissue. We assessed the levels of LXA4 and RvD1, along with their metabolic LOX enzymes, in elective (control) and sporadic miscarriage samples. We investigated the effects of LXA4 and RvD1 on decidualization using primary endometrial stromal cells and the immortalized endometrial stromal St-T1b cell line. The upregulation of 12- and 15-LOX expression was observed in pregnancy tissue after sporadic miscarriage, suggesting an inflammatory imbalance. Furthermore, incubation with these lipid mediators led to a decrease in decidualization biomarkers PRL and IGFBP-1, accompanied by morphological changes indicative of aberrant differentiation. The expression of LOX enzymes in decidual natural killer cells suggests their involvement in regulating the inflammatory surroundings and the extent of decidualization.