Role of Sphingosine 1-phosphate Signalling and Endocannabinoids System in Uterine Disorders: Endometriosis, Adenomyosis, Uterine fibroids

This thesis investigates the role of sphingosine-1-phosphate (S1P) signaling and its interaction with the endocannabinoid system (ECS) in the pathogenesis of major gynecological disorders, including endometriosis, adenomyosis, and uterine fibroids. Endometriosis and adenomyosis are chronic inflammatory conditions characterized by ectopic growth of endometrial-like tissue, leading to pain, infertility, fibrosis, and altered tissue function. Uterine fibroids (leiomyomas), although benign, represent the most common tumors in women of reproductive age and can significantly impact quality of life. Despite their prevalence, the molecular mechanisms underlying these disorders remain incompletely understood. S1P is a bioactive sphingolipid involved in key cellular processes such as proliferation, inflammation, and fibrosis. Increasing evidence suggests that dysregulation of S1P signaling contributes to the progression of gynecological diseases. In parallel, the ECS has been implicated in endometriosis pathophysiology, particularly in modulating inflammation and pain. In this study, we first evaluated the expression of endocannabinoid receptors (CB1, CB2, and GPR18) in human endometriotic and adenomyotic tissues, demonstrating their upregulation compared to healthy controls. Functional experiments in endometriotic epithelial cells showed that the endocannabinoid 2-arachidonoylglycerol (2-AG) significantly increased the expression of pro-inflammatory markers (IL-1β, IL-6, IL-8, and COX-2), whereas the stable anandamide analogue methanandamide did not exert similar effects. Importantly, silencing of the S1P3 receptor abolished the pro-inflammatory response induced by 2-AG, highlighting a critical crosstalk between ECS and S1P signaling. Furthermore, we demonstrated that S1P selectively promotes proliferation in leiomyoma cells, but not in normal myometrial cells, via S1P2 receptor activation and downstream ERK1/2 and ERM signaling pathways. In endometriosis, S1P was shown to induce fibrosis by promoting epithelial–mesenchymal transition (EMT) and upregulating fibrotic markers. Mechanistically, these effects were mediated by S1P3 and its downstream effectors, including ERK1/2 and ezrin signaling. Notably, S1P3 expression was significantly increased in endometriotic tissues and positively correlated with fibrosis severity. Overall, this work identifies S1P signaling as a central regulator of inflammation, fibrosis, and proliferation in gynecological disorders, and reveals a novel interaction between S1P and the endocannabinoid system. These findings provide new insights into disease mechanisms and suggest potential therapeutic targets for the development of more effective treatments.