Mbadhi, M. N.; Fujiwara, H.; Gill, R.; Mitchum, K. T.; Lin, C.; Raghuraman, N.; Frolova, A. I.

BACKGROUND: Dysregulated myometrial contractility contributes to obstetric complications. Sphingosine 1 phosphate (S1P) is an important inflammatory regulator in the myometrium and decidua, yet its metabolic dynamics during pregnancy are poorly characterized. This study aimed to profile the expression of S1P metabolic enzymes and receptors, and quantify sphingolipid metabolism in human gestational tissues across pregnancy. METHODS: Myometrium, decidua parietalis, and chorioamnion were collected from women undergoing cesarean sections at term ([&ge;]37 weeks gestation) without labor (TNL), at term with labor (TL), and preterm (<37 weeks gestation) without labor (PTNL). Messenger RNA (mRNA) expression of S1P metabolic enzymes and receptors was assessed using quantitative polymerase chain reaction, while sphingolipids were quantified using targeted liquid chromatography-tandem mass spectrometry. RESULTS: S1P metabolic enzymes and receptors were differentially expressed across gestational tissues. At TNL, SPHK1 expression was significantly higher in the decidua parietalis than in the chorioamnion and myometrium. The myometrium exhibited the highest mRNA expression of S1P receptors compared to the decidua and chorioamnion. At term, S1P was more abundant in the myometrium than in the decidua parietalis and chorioamnion. Both SPHK1 and S1P were significantly increased in TL compared to TNL myometrium. S1P levels were higher in the myometrium at TNL compared to PTNL, while no significant differences were observed in the decidua and chorioamnion. Overall, sphingolipid metabolism was highest in the decidua and myometrium and lowest in the chorioamnion at term. CONCLUSION: These findings reveal tissue specific regulation of S1P metabolism and signaling in human gestational tissues, suggesting a therapeutic role of S1P in modulating myometrial contractility.