The Role Of Estrogen-mediated Mast Cell Activation In Endometriosis Pain

BackgroundEndometriosis is a common gynecological disease referred to the implantation and growth of endometrial glands and stroma outside the uterus or myometrium.Its incidence of women in their reproductive age is up to 15%and symptoms of endometriosis include several types of pain such as severe dysmenorrheal,deep dyspareunia dyschezia and chronic pelvic pain as well as reduced fertility.The mechanism of endometriosis pain is still unclear,resulting in its lack of a good clinical treatment.Therefore,it is necessary to actively study the mechanism of endometriosis pain to obtain specific molecular targets for effective prevention and treatment.Endometriosis is an estrogen-dependent disease.Estrogen is the root cause of endometriosis,and is also involved in the regulation of the whole process of neuroinflammatory pain in endometriosis.However,the mechanism about estrogen promote the production of inflammatory cytokines and sensitization of the nerves that leading to hyperalgesia is still not clear.Mast cell(MC)is an important kind of cells in immune inflammatory response.In recent years,a large number of studies have found that the increased MC density and activated MC in endometriosis lesions,where there is a close relationship between the MC and nerve fibers.In addition,stem cell factor(SCF)is also known to increase in the peritoneal fluid of women with endometriosis.The MC located close to nerve can degranulate by releasing histamine,tryptase,tumor necrosis factor-a(TNF-a)and nerve growth factor(NGF)that can sensitize sensory neurons,and sensitization of nerve can up-regulate the production of neuropeptide substances such as substance P(SP)and calcitonin gene-related peptide(CGRP)to active MC degranulate in turn resulting in continuous state of neuropathic pain.Since the presence of estrogen receptors on MC,local high level of E2 in endometriosis lesions can directly activate MC to exert their biological effects.Based on the above researches,we designed our experiments.First,we determined the concentrations of E2,the number of activated MCs,and the ratio of degranulation/total number of MCs in ovarian endometriotic lesions,as well as in eutopic and normal endometrium.We also determined the correlations between local E2 levels,the number of degranulated MCs,and a variety of clinical parameters.Secondly,we investigated the effects of E2 on the degranulation of RBL2H3 cells and then induced neurite outgrowth of PC 12 cells,along with the peripheral sensitivity of dorsal root ganglion(DRG)cells in response to high concentrations of E2,a condition similar to that seen in endometriosis.Finally,we observed the migration of RBL2H3 cells using a transwell migration assay and detected the release of MC-associated mediators in ovarian endometriotic cells in vitro.In the present study,we aimed to investigate the effects of local E2 upon the recruitment and degranulation of MCs in endometriosis lesions and determine whether these cells are involved in the pain associated with endometriosis that may provide new ideas for the treatment of endometriosis pain.ObjectiveTo investigate the effects of local E2 upon the recruitment and degranulation of MCs in endometriosis lesions and determine whether they are involved in the endometriosis pain.Materials and methodsThe concentrations of E2,and number and activity of MCs in endometrial tissues were determined by using enzyme-linked immunosorbent assay(ELISA)and immunohistochemistry,respectively,and then correlated with endometriosis status.The migration of RBL2H3 cells were evaluated by the transwell migration assay,and their degranulation were measured through the release of ?-hexosaminidase(?-hex).Coculture of RBL2H3 cells and PC 12 cells,or with DRG cells,were performed with E2 intervention,and neurite outgrowth of PC 12 cells and peripheral sensitization of DRG cells were determined.Results1.High concentrations of E2 in ovarian endometriotic lesions are positively correlated with endometriosis-related dysmenorrhea.2.The number and activity of MCs were higher in ovarian endometriotic lesions compared with controls,which are positively correlated with endometriosis-related dysmenorrhea but not the size of ovarian endometriotic cysts.3.Activation of RBL2H3 cells by E2 can trigger the release of biologically active NGF that can promote neurite outgrowth of PC 12 cells and the expression of Trpvl and Nav1.8 in DRG cells.4.Endometriotic cells can promote RBL2H3 cell recruitment by up-regulating the expression levels of SCF,TGF-? and MCP1 with the treatment of E2.Conclusion1.Both of the high level of E2 and high number of degranulated MCs in ovarianendometriotic lesions are positively correlated with endometriosis-related dysmenorrhea.2.High level of E2 in ovarian endometriomas could recruit and activate MCs,which may play a role in endometriosis-associated dysmenorrhea through the release of biologically active NGF that can promote nerve growth and nerve sensitization.