bims-reprim Biomed News
on Reproductive immunology
Issue of 2021‒01‒31
three papers selected by
Iva Filipovic
Karolinska Institutet


  1. Hum Reprod. 2021 Jan 25. 36(2): 415-428
    Hey-Cunningham AJ, Wong C, Hsu J, Fromm PD, Clark GJ, Kupresanin F, Miller EJ, Markham R, McGuire HM.
      STUDY QUESTION: What are the detailed endometrial tissue specific and systemic dendritic cell (DC) subset disturbances in endometriosis?SUMMARY ANSWER: This study confirms myeloid DC (mDC) and plasmacytoid DC subsets are readily identified in endometrial tissue and shows both endometrial and circulating differences in DC populations in women with endometriosis, with disease stage-specific relationships evident locally in the endometrium.
    WHAT IS KNOWN ALREADY: Immune factors in the uterus, the peritoneal environment and systemically are implicated in the pathogenesis and progression of both endometriosis and infertility. While there is some evidence that endometrial DC populations are altered in endometriosis, DC subset involvement in both the endometrium and peripheral blood have not been comprehensively investigated so the functional consequences have been unknown.
    STUDY DESIGN, SIZE, DURATION: This prospective cross-sectional cohort study compares circulating and endometrial DC populations in women of reproductive age with and without endometriosis (n = 55 and 30, respectively), wherein each participant donated samples at a single time point. Study participants were surveyed for menstrual cycle phase, American Society for Reproductive Medicine (ASRM) endometriosis disease stage and fertility status (where possible).
    PARTICIPANTS/MATERIALS, SETTING, METHODS: Peripheral blood samples were processed into mononuclear cells for analysis by flow cytometry, and endometrial samples were analysed by immunohistochemistry and dissociated into single-cell suspension for flow cytometry.
    MAIN RESULTS AND THE ROLE OF CHANCE: In the endometrium of women with endometriosis, IRF-8+ cells were increased during the proliferative phase (P = 0.014), total DC proportions increased in the secretory phase (P = 0.038) and normal menstrual cyclical fluctuations in CD1c+ and IRF-8+ cells blunted; indicative of a consistently inflammatory tissue environment. The inflammatory changes in CD141+ and IRF-8+ populations in the endometrium of women with endometriosis were particularly evident in more advanced ASRM stages of the disease (respective P-values 0.032 and 0.045). There was also evidence of systemic inflammation in women with endometriosis, with increased circulating CD141+ mDC proportions (overall P = 0.040, secretory phase P = 0.021).
    LARGE SCALE DATA: N/A.
    LIMITATIONS, REASONS FOR CAUTION: As is common in this type of study, one of the main limitations was small sample numbers, particularly during the menstrual phase of the cycle.
    WIDER IMPLICATIONS OF THE FINDINGS: Further phenotyping of local and circulating immune cell subtypes is critical to improving understanding of endometriosis pathogenesis and immune contributions to infertility associated with the disease.
    STUDY FUNDING/COMPETING INTEREST(S): This research was financially supported by a Sydney Medical School and Balnaves Foundation Kick Start Grant and the Department of Obstetrics, Gynaecology and Neonatology at The University of Sydney. The authors have no conflicts of interest to declare.
    Keywords:  blood; dendritic cells; endometriosis; endometrium; flow cytometry; immunohistochemistry; inflammation; menstrual cycle
    DOI:  https://doi.org/10.1093/humrep/deaa318
  2. Hum Reprod. 2021 Jan 26. pii: deaa379. [Epub ahead of print]
    Reavey JJ, Walker C, Nicol M, Murray AA, Critchley HOD, Kershaw LE, Maybin JA.
      STUDY QUESTION: Can markers of human endometrial hypoxia be detected at menstruation in vivo?SUMMARY ANSWER: Our in vivo data support the presence of hypoxia in menstrual endometrium of women during physiological menstruation.
    WHAT IS KNOWN ALREADY: Current evidence from animal models and human in vitro studies suggests endometrial hypoxia is present at menstruation and drives endometrial repair post menses. However, detection of human endometrial hypoxia in vivo remains elusive.
    STUDY DESIGN, SIZE, DURATION: We performed a prospective case study of 16 women with normal menstrual bleeding.
    PARTICIPANTS/MATERIALS, SETTING, METHODS: Reproductively aged female participants with a regular menstrual cycle underwent objective measurement of their menstrual blood loss using the alkaline haematin method to confirm a loss of <80 ml per cycle. Exclusion criteria were exogenous hormone use, an intrauterine device, endometriosis or fibroids >3 cm. Participants attended for two MRI scans; during days 1-3 of menstruation and the early/mid-secretory phase of their cycle. The MRI protocol included dynamic contrast-enhanced MRI and T2* quantification. At each visit, an endometrial sample was also collected and hypoxia-regulated repair factor mRNA levels (ADM, VEGFA, CXCR4) were quantified by RT-qPCR.
    MAIN RESULTS AND THE ROLE OF CHANCE: Women had reduced T2* during menstrual scans versus non-menstrual scans (P = 0.005), consistent with menstrual hypoxia. Plasma flow (Fp) was increased at menstruation compared to the non-menstrual phase (P = 0.0005). Laboratory findings revealed increased ADM, VEGF-A and CXCR4 at menstruation on examination of paired endometrial biopsies from the menstrual and non-menstrual phase (P = 0.008; P = 0.03; P = 0.009). There was a significant correlation between T2* and these ex vivo hypoxic markers (P < 0.05).
    LIMITATIONS, REASONS FOR CAUTION: This study examined the in vivo detection of endometrial hypoxic markers at specific timepoints in the menstrual cycle in women with a menstrual blood loss <80 ml/cycle and without significant uterine structural abnormalities. Further research is required to determine the presence of endometrial hypoxia in those experiencing abnormal uterine bleeding with and without fibroids/adenomyosis.
    WIDER IMPLICATIONS OF THE FINDINGS: Heavy menstrual bleeding (HMB) is a common, debilitating condition. Understanding menstrual physiology may improve therapeutics. To our knowledge, this is the first in vivo data supporting the presence of menstrual hypoxia in the endometrium of women with normal menstrual bleeding. If aberrant in those with HMB, these non-invasive tests may aid diagnosis and facilitate personalized treatments for HMB.
    STUDY FUNDING/COMPETING INTEREST(S): This work was funded by Wellbeing of Women grant RG1820, Wellcome Trust Fellowship 209589/Z/17/Z and undertaken in the MRC Centre for Reproductive Health, funded by grants G1002033 and MR/N022556/1. H.O.D.C. has clinical research support for laboratory consumables and staff from Bayer AG and provides consultancy advice (but with no personal remuneration) for Bayer AG, PregLem SA, Gedeon Richter, Vifor Pharma UK Ltd, AbbVie Inc; Myovant Sciences GmbH. H.O.D.C. receives royalties from UpToDate for articles on abnormal uterine bleeding.
    TRIAL REGISTRATION NUMBER: N/A.
    Keywords:  MRI; endometrium; gynaecology; hypoxic; menorrhagia; menses; menstrual; perfusion; progesterone
    DOI:  https://doi.org/10.1093/humrep/deaa379
  3. Front Immunol. 2020 ;11 563073
    Livson S, Jarva H, Kalliala I, Lokki AI, Heikkinen-Eloranta J, Nieminen P, Meri S.
      Background: Human pregnancy alters profoundly the immune system. The local involvement and mechanisms of activation of the complement system in the cervicovaginal milieu during pregnancy and delivery remain unexplored.Objectives: To determine whether normal pregnancy and delivery are associated with local activation of complement or changes in the immunoglobulin profile in the cervix.
    Study Design: This study was designed to assess IgA, IgG, and complement activation in the cervicovaginal area in three groups of patients: i) 49 pregnant women (week 41+3-42+0) not in active labor, ii) 24 women in active labor (38+4-42+2), and iii) a control group of nonpregnant women (n=23) at child-bearing age. We collected mucosal samples from the lateral fornix of the vagina and external cervix during routine visits and delivery. The Western blot technique was used to detect complement C3 and its activation products. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and analyzed. IgA and IgG were analyzed by Western blotting and quantified by ELISA. One-way ANOVA and Tukey's Multiple Comparison tests were used for statistical comparisons.
    Results: A higher abundance but lower activation level of C3 in both the external cervix (P<0.001) and lateral fornix of the vagina (P<0.001) was observed during delivery (58 ± 22, n= 24) in comparison to the groups of nonpregnant (72 ± 13%; mean ± SD, n=23) and pregnant women (78 ± 22%, n=49). Complement activating IgG was detected in higher abundance than IgA in the cervicovaginal secretions of pregnant women. In a small proportion samples also C3-IgG complexes were detected.
    Conclusions: Our results reveal an unexpectedly strong activation of the complement system and the presence IgG immunoglobulins in the cervicovaginal area during pregnancy, active labor, and among nonpregnant women. In contrast to the higher amounts of C3 in the cervicovaginal secretions during labor, its activation level was lower. Complement activating IgG was detected in higher concentrations than IgA in the mucosal secretions during pregnancy and labor. Taken together our results imply the presence a locally operating humoral immune system in the cervicovaginal mucosa.
    Keywords:  C3; IgA; IgG; delivery; inflammation; parturition; uterine cervix; vaginal mucosa
    DOI:  https://doi.org/10.3389/fimmu.2020.563073