{"paper_id":"96ee2001-7135-46f6-8ddc-315e7271b1e0","body_text":"MultiMENDo ProjectMultiMENDo Project\nThe quest for better \nendometriosis care \nEndometriosis is a common gynaecological \ndisease defined by the presence of lesions \nof functional endometrial tissue outside \nthe uterine cavity (ectopic endometrium). \nIt affects approximately 10 per cent of \nwomen in their reproductive years (from \npuberty to menopause).\nThe most common symptoms are pelvic \npain (during the menses and chronically) \nand pain during intercourse (Chapron et \nal., 2019). Usually, the intensity of these \npain symptoms is high. Other symptoms \ninclude painful bowel movements/ \nconstipation/diarrhoea, painful urination, \nfatigue, depression or anxiety, abdominal \nbloating and nausea. In some cases, \nendometriosis can be asymptomatic. So, \nthe manifestation of the disease is quite \nvariable across patients, participating in \nthe delay of its diagnosis. Furthermore, \ninfertility, which can be seen as a silent \nsymptom (unknown until the patient \ntries to conceive), is associated with \nendometriosis in around 40 per cent of \npatients. Endometriosis is also associated \nwith an increased risk of miscarriage and \npregnancy complications (Leone Roberti  \nMaggiore et al., 2016).\nEndometriosis patients can be classified \ninto three subgroups according to \nthe lesion localisation and infiltration: \nsuperficial peritoneal lesions, ovarian \nendometriosis (also called endometrioma) \nand deep infiltrating endometriosis \n(Chapron et al., 2019).\nSo endometriosis is a major health issue \nthat strongly affects the quality of life of \npatients and is an economic burden, with \na cost estimated at ≈10 k€ per year per \npatient (Simeons et al., 2012). \nEndometriosis diagnosis\nAs the symptoms are not very specific \n(and sometimes wrongly dismissed), the \ndiagnosis of endometriosis is difficult and \nis usually considered definitive only after \na lesion histological analysis, requiring an \ninvasive procedure. However, the current \nguidelines (from several national and \ninternational societies) recommend the \nuse of hormonal therapy as a first line of \ntreatment in suspected endometriosis \ncases to avoid unnecessary invasive \nprocedures if the medical treatment is \nefficient in reducing the pain symptoms \n(Kalaitzopoulos et al., 2021). Imaging \nis also a proposed tool in diagnosing \nendometriosis, i.e. transvaginal ultrasound \n(TVUS) and magnetic resonance \nimaging (MRI). Depending on the \nlesion localisation and the interpreter \nexperience, the detection rate with these \nmethods is highly variable. Therefore, \nusing imaging for endometriosis diagnosis \nhas several limitations: the cost of these \ntechnologies, the false negative rate \nthat is not negligible (5 to 20 per cent) \nand their effectiveness that is highly \ndependent on the image interpretation, \nan expertise rarely available in a primary \ncare setting. So, one of the current high-\nstakes goals of endometriosis patient care \nis the development of reliable methods \nfor early non-invasive diagnosis. Despite \nnumerous efforts, in a variety of tissues, \nbut mainly in peripheral blood or semi-\ninvasively in endometrium or peritoneal \nfluid (Brulport et al., 2024), no biomarkers \nor a combination of those (including \nimaging data) was found and validated \nwith sufficient sensitivity and specificity \nfor use in clinical practice (Nisenblat et \nal., 2016a–b; Gupta et al., 2016). As a \nFigure 1: Endometriosis is characterised by lesions of ectopic endometrium. Schematic representation of the healthy (A) and endometriosis-affected (B) female \nreproductive tract with its surroundings. The positioning of a menstrual cup is shown (A). Lesion site of abnormally located endometrium (ectopic) defines the \nthree commonly used subtypes (superficial, ovarian and deep infiltrating). The uterine endometrium changes during the menstrual cycle, and it is shed during the \nmenses (C). Source: BioRender.com.\nAdobe Stock © freshidea\nEndometriosis is a common heterogeneous \ngynaecological disorder\n98\n 99\nDISSEMINATION DISSEMINATION\n\n\nMultiMENDo Project\nresult of these aspects, there is a delayed \ndiagnosis, estimated to be eight years \n(Ghai et al., 2020).\nEndometriosis treatment\nThe current treatments for endometriosis \nare based on medical and surgical \napproaches for pain management and \nassisted reproductive technologies (ART) \n(and/or surgery) for infertility. There is \nstill a lot of dissensus for endometriosis \ntreatment (Kalaitzopoulos et al., 2021) \nand a global lack of long-term efficacy of \nthe available options.\nThe medical treatment (Barbara et al., \n2021; Barra et al., 2019; Becker et al., \n2017; Donnez and Dolmans, 2021) \nbasically consists of inducing amenorrhea \n(to suppress the shedding of the \nendometriotic lesions) using hormonal \ntreatments, in combination with pain meds \nif necessary. As such, it is symptomatic \nand not curative, and the beneficial effect \nis usually lost upon treatment cessation. \nUsually proposed as first-line therapies \nare the combined oral contraceptives \n(oestrogen-progestins) and progestins. \nTheir efficacy on dysmenorrhoea is usually \nhigher than on non-menstrual pelvic \npain. Gonadotropin-releasing hormone—\nGnRH—agonists and antagonists are \nproposed as second-line treatments. \nThey were shown to be effective on \nmenstrual and non-menstrual pelvic pain. \nConcerning the response to these medical \ntreatments, 15–30 per cent of patients \ndo not respond to these options. These \nmedical options have shown no benefit \nfor the fertility of endometriosis patients.\nThe surgical treatment (Kalaitzopoulos \net al., 2021; Singh et al., 2020) is \na potentially curative option. The \nrecommendation for surgery is a lack \nof pain relief (due to medical treatment \ninefficacy or intolerance). Surgical \nexcision of all the lesions by laparoscopy \nis recommended in an expert centre as \nlesions may involve several other organs \nfrom the pelvic cavity (bowel, urinary \ntract, etc.). Surgery is efficient, but pain \nrelief is sometimes incomplete, and \nrecurrence of pain is observed in seven \nto 28 per cent of patients within two \nyears of the surgery. Around 20 per cent \nof patients undergo further surgery in the \nfollowing two and a half years, indicating \nthe recurrence of the endometriotic \nlesion(s). Unlike medical treatment, \nsurgery may provide benefits for fertility. \nHowever, endometrioma surgery can \nnegatively impact ovarian reserve and \ndoes not improve the outcome of in vitro \nfertilisation (IVF) in infertile patients.\nThe fertility treatment (Kalaitzopoulos \net al., 2021; Singh et al., 2020) mostly \nrelies on IVF. Endometriosis is known \nto contribute to subfertility via several \nmechanisms: pelvic adhesions, distorted \npelvic anatomy, bilateral tubal blockage, \npoor quality of the oocyte/embryo and/or \nendometrial environment. Interestingly, \nit was shown that deferring the embryo \ntransfer in endometriosis-affected \nwomen was associated with significantly \nhigher cumulative pregnancy rates \n(Bourdon et al., 2018), probably due to a \nbetter endometrial environment in a cycle \nwithout ovarian stimulation. Concerning \nthe response to IVF fertility treatment, \na meta-analysis (Barbosa et al., 2014) \nshowed that women with endometriosis \nhave practically the same chance of \nachieving clinical pregnancy and live birth \nas women with other causes of infertility. \nIVF success rate is around 40 per cent \n(with a strong influence being the patient’s \nage at the time of egg retrieval).\nSo, treatment options are imperfect and \nvery limited data are available to predict \nwhich treatment will work for which \npatient.\nEndometriosis \npathophysiology is not  \nwell understood\nThe strongest hypothesis for the origin \nof endometriotic lesions is retrograde \nmenstruation, a reflux of menstrual \nblood through the fallopian tubes \ninto the peritoneal cavity. But as this \nphenomenon occurs in 90 per cent \nof menstruating women and only 1 \nin 10 develops endometriosis, other \nmechanisms are at play. Individual \nsusceptibilities involving intrinsic specific \nalterations of eutopic (uterine) and/\nor ectopic endometrium (high survival \ncapacity, invasive and proliferative \ncapabilities, somatic mutation), as well \nas alterations of the local peritoneal \nenvironment (excessive inflammation, \ndefective immune clearance of ectopic \ncells, oxidative stress) are thought to be \nkey aspects of the pathophysiology.\nIndeed, endometriotic lesions have an \naltered gene expression profile compared \nto eutopic endometrium (normally \nlocalised within the uterus) (Borghese \net al., 2008), with increased survival \nand adhesion signatures. The eutopic \nendometrium from endometriosis patients \nis also altered compared to healthy \ncontrol, with notable differences involved \nin immunity (Rai et al., 2010; Poli-Neto \net al., 2020). A single-cell transcriptomic \nstudy on endometrium from healthy \ndonors, endometrium and endometriotic \nlesion from endometriosis patients \n(all obtained by invasive procedures) \nshowed that several cell subtypes from \nthe patients’ eutopic endometrium share \nalterations with endometriotic lesions \n(Ma et al., 2021). An aberrant immune \nresponse seems crucial for enabling the \nectopic proliferation of endometrial cells \n(Vallvé-Juanico, Houshdaran and Giudice, \n2019). Not only do peritoneal immune \ncells fail to clear the endometriotic lesions, \nbut they also appear to promote their \nproliferation and invasion capabilities \n(Jeung, Cheon, and Kim, 2016; Chan et \nal., 2017). Immunomodulation may be \nan interesting strategy for the treatment \nof endometriosis (Jeljeli et al., 2020). As \nimmune cells are involved in implantation \nand placentation (Ander, Diamond, \nand Coyne, 2019), modulating them \nmay benefit fertility. The MultiMENDo \nproject’s coordinator led a study showing \nthat  pre-conceptional  immunomodulation \nalters immune cell recruitment at \nthe maternal-foetal interface in mice \n(Dang et al., 2021). In the inflammatory \ncontext of endometriosis, such an effect \nmay be beneficial. Menstrual immune \ncells are also refluxed in the peritoneal \ncavity, but they were scarcely studied \nin endometriosis (Schmitz et al., 2021; \nWarren et al., 2018), and their potential \npathogenic role remains to be evaluated.\nMenstrual blood is an easily \naccessible yet understudied  \nbiological fluid\nMenstrual blood is an easily accessible \nbiological fluid available monthly in non-\npregnant women of reproductive age. \nAmongst the naturally available biological \nfluids, it is by far one of the least studied, \nwith 37 to 189 times fewer biomedical \nresearch studies for menstrual blood \nthan other biological fluids (peripheral \nblood, saliva, urine samples, faeces/stool, \nor seminal fluid/sperm). This illustrates \nthat menstrual blood has been greatly \noverlooked as a biological fluid so far.\nThe increased popularity of reusable items \nof personal feminine hygiene products, \nsuch as the menstrual cup, makes it \nvery easy to collect. This collection \nmethod greatly improves the possibility \nof studying viable cells (immune and \nendometrial cells) from this fluid and \nsecreted factors in the menstrual serum. \nMenstrual immune cells resemble the \nuterine microenvironment more than the \ncirculating immune cells (van der Molen \net al., 2014). While menstrual blood is \neasily accessible and relevant to both \ngynaecological disorders and fertility, \nthere is an extremely low number of \nstudies on this biological fluid. Most \nstudies focused on its use as a source of \nmesenchymal stem cells for regenerative \ntherapies (Lv et al., 2018). A few studies \nusing menstrual blood in the context \nof endometriosis have shown some \npromise (Nikoo et al., 2014; Warren et \nal., 2018; Schmitz et al., 2021; Shih et al., \n2022), but so far, the number of included \npatients was limited. Collecting both \nmenstrual immune and endometrial cells \nfrom a higher number of women with \nno or different types of endometriosis \nis therefore relevant for a search for \nendometriosis biomarkers that could \ntruly impact diagnosis, understanding \nand treatment of this disease.\nMultiMENDo project\nThe MultiMENDo project aims to \nidentify relevant differences in menstrual \nblood between healthy donors and those \nwith endometriosis. The project also \nlooks at variations within subgroups \nof people with endometriosis. These \ndifferences could become reliable signs \nfor diagnosing or predicting outcomes \n(biomarkers). MultiMENDo seeks to \nunderstand how endometriosis develops \nand explore new ways to treat it. \nFor this, single-cell transcriptomics and \nsoluble protein multiplex assays will be \nused on 64 menstrual blood samples to \nidentify candidate diagnostic biomarkers \nthat differentiate endometriosis-affected \nwomen from healthy controls. Validation \nof these biomarkers will be carried out \nin menstrual blood samples from 250 \nwomen (200 endometriosis-affected \nwomen with different subtypes of \nendometriosis). Prognostic candidate \nbiomarkers for response to surgery and \nin vitro fertilisation will be identified \nin menstrual blood from patients with \nlongitudinal monitoring. Menstrual-\nfluid-derived organoids cultured with \nor without immune cells will be used \nto assess endometriosis-associated \nfunctional changes and to test new \nimmunomodulatory treatments. The \nMultiMENDo project will lead to \nbetter endometriosis care and improve \nour understanding of endometriosis \npathophysiology. It will also broaden \nthe study of menstrual blood, a greatly \noverlooked biological fluid relevant \nto gynaecological and reproductive \ndisorders.\nReferences click here\nPROJECT SUMMARY\nThe MultiMENDo project focuses on \nendometriosis, a gynaecological disorder \naffecting approximately 10 per cent of \nwomen of childbearing age. This complex \ndisease is notably associated with chronic \npelvic pain and infertility, leading to a \nreduced quality of life. There is a huge \ndiagnostic delay and a lack of curative \ntherapies. The project aims to find \ndiagnostic and prognostic biomarkers and \ninvestigate new therapeutic approaches \nusing menstrual blood, a relevant and easily \naccessible yet overlooked biological fluid.\nPROJECT LEAD PROFILE\nLudivine Doridot is a researcher at INSERM \n(French National Institute of Health and \nMedical Research) and an Associate \nProfessor at Université Paris Cité (Paris, \nFrance). She obtained her PhD in Genetics \nfrom Université Paris Descartes in 2013 for \nher studies on preeclampsia, a hypertensive \ndisease of pregnancy. She then performed \na postdoc in Beth Israel Deaconess Medical \nCenter, a Harvard-affiliated hospital in \nBoston (USA), where she studied genetic-\nenvironment interaction in the context of \nmetabolic syndrome. Since 2017, she has \nfocused on endometriosis and reproductive \nimmunology.\nPROJECT CONTACTS\nLudivine Doridot\nBatiment Gustave Roussy, 4ème étage\n22 rue Mechain, 75014 Paris, France\nludivine.doridot@inserm.fr \nhttps:/ /institutcochin.fr/en/\nresearch-project/endometriosis-\nphysiopathology-pregnancy-\nimmunomodulatory-treatments \n/ludivine-doridot/\nFUNDING\nThis project has received funding from the \nEuropean Research Council (ERC) under the \nEuropean Union’s Horizon 2020 research and \ninnovation programme under grant agreement \nNo. 101078556.\n100\n 101\nDISSEMINATION DISSEMINATION","source_license":"CC0","license_restricted":false}