Sphingosine-1-phosphate receptor 3 is a non-hormonal target to counteract endometriosis-associated fibrosis

Abstract

ObjectiveTo study the molecular mechanisms responsible for fibrosis in endometriosis by investigating whether the protein expression levels of sphingosine-1-phosphate receptor 3 (S1PR3), one of the five specific receptors of the bioactive sphingolipid sphingosine 1-phosphate (S1P), correlated with fibrosis extent in endometriotic lesions and which are the cellular mechanisms involved in this process. DesignCase-control laboratory study and cultured endometriotic cells. SubjectsUniversity research institute and university hospital. Patient(s)A total of 33 women, with and without endometriosis, were included in the study. Interventions(s)Endometriotic lesions were obtained from women with endometriosis (endometrioma [OMA], n=8; deep infiltrating endometriosis [DIE], n=15, (urological n=5, gastrointestinal n=6, posterior n=4)) and control endometrium from healthy women, n=10, by means of laparoscopic/hysteroscopic surgery. The expression of S1PR3 was evaluated by immunohistochemistry and the extent of fibrosis by Masson’s trichrome staining. Human cultured epithelial endometriotic 12Z cells were used to evaluate the mechanisms involved in the profibrotic effect of S1PR3 activation. Main Outcome Measure(s)The expression of S1PR3 in endometriotic lesions positively correlated to endometriosis-associated fibrosis. In addition, S1P induced epithelial-mesenchymal transition (EMT)/fibrosis in epithelial endometriotic cells. By RNA interference and pharmacological approaches, the profibrotic effect of S1P was shown to rely on S1PR3, thus unveiling the molecular mechanism implicated in the profibrotic action of the bioactive sphingolipid. Result(s)The protein expression levels of S1PR3 resulted significantly augmented in the glandular sections of OMA and DIE of different localizations in respect to control endometrium and positively correlated with the extent of fibrosis. S1P was shown to have a crucial role in the onset of fibrosis in epithelial endometriotic cells, stimulating the expression of EMT and fibrotic markers. Genetic approaches highlighted that S1PR3 mediates the fibrotic effect of S1P. Downstream of S1PR3, ezrin and ERK1/2 signaling were found critically implicated in the EMT/fibrosis elicited by S1P. Conclusion(s)The S1PR3 receptor may represent a possible innovative pharmacological target for endometriosis.