Current concepts of the mechanisms of menstruation: a normal process of tissue destruction

Menstrual Blood-Derived Mesenchymal Stem Cells: Women's Attitudes, Willingness, and Barriers to Donation of Menstrual Blood

Background: Menstrual blood contains mesenchymal stem cells (MenSC), considered a potential "off-the-shelf" treatment for a range of diseases and medical conditions. Samples of menstrual blood can be collected painlessly, inexpensively, and as frequently as every month for cell therapy. While there has been considerable previous research into the clinical advantages of MenSC, there is currently little understanding of potential donors' attitudes regarding menstrual blood donation and MenSC. Methods: One hundred women 18 years of age or over were surveyed to understand attitudes and potential barriers to menstrual blood donation. The questionnaire assessed participant age and brief medical history (giving birth, donating blood, donating stem cells), menstrual experience (period rating, preferred menstrual hygiene products), and whether participants would donate MenSC or accept MenSC therapy. Results: MenSC was met with a generally positive response, with 78% of menstruating women willing to donate menstrual blood. No significant relationship was recognized between willingness to donate menstrual blood with age, history of childbirth or blood donation, menstruation perception, and preferred menstrual hygiene product. Women rated their period experience better after being made aware of the ability to donate menstrual blood, meaning MenSC therapy can be beneficial for donors as well as patients. Conclusions: Considering women's attitudes to MenSC and donation of menstrual blood, the future of MenSC therapy is positive; women are generally willing to donate menstrual blood, independent of age, perception of periods, and history of childbirth and blood donation.

In silico study of principal sex hormone effects on post-injury synovial inflammatory response

Following an anterior cruciate ligament injury, premenopausal females tend to experience poorer outcomes than males, and sex hormones are thought to contribute to the disparity. Evidence seems to suggest that the sex hormones estrogen, progesterone, and testosterone may regulate the inflammation caused by macrophages, which invade the knee after an injury. While the individual effects of hormones on macrophage inflammation have been studied in vitro, their combined effects on post-injury inflammation in the knee have not been examined, even though both males and females have detectable levels of both estrogen and testosterone. In the present work, we developed an in silico kinetic model of the post-injury inflammatory response in the human knee joint and the hormonal influences that may shape that response. Our results indicate that post-injury, sex hormone concentrations observed in females may lead to a more pro-inflammatory, catabolic environment, while the sex hormone concentrations observed in males may lead to a more anti-inflammatory environment. These findings suggest that the female hormonal milieu may lead to increased catabolism, potentially worsening post-injury damage to the cartilage for females compared to males. The model developed herein may inform future in vitro and in vivo studies that seek to uncover the origins of sex differences in outcomes and may ultimately serve as a starting point for developing targeted therapies to prevent or reduce the cartilage damage that results from post-injury inflammation, particularly for females.

Anti-inhibitory potential of an ethanolic extract of Distromium decumbens on pro-inflammatory cytokine production in Pseudomonas aeruginosa lipopolysaccharide-stimulated nasal polyp-derived fibroblasts

Marine algae are rich sources of biologically active compounds that may present useful leads in the development of pharmaceuticals, nutraceuticals, and functional foods. The main aim of this study was to identify the possible anti-inflammatory effects of Distromium decumbens in nasal polyp-derived fibroblasts (NPDFs) and its associated mechanism of action. NPDFs were stimulated by Pseudomonas aeruginosa lipopolysaccharide (PA-LPS) and treated with an ethanolic extract of Distromium decumbens (DDE). The production of interleukin-6 (IL-6) and IL-8 in the supernatant, the phosphorylation of mitogen-activated protein kinase (MAPK) molecules [extracellular signal-related kinase 1/2 (ERK1/2), c-Jun N-terminal kinase and p38 MAPK] and Akt, and the activation of nuclear factor-κB (NF-κB) were assayed in the PA-LPS-stimulated NPDFs untreated or treated with DDE. The expression levels of IL-6 and IL-8 in PA-LPS-exposed NPDFs were detected using enzyme-linked immunosorbent assays. The mechanisms by which DDE regulates cellular signaling cascades were investigated using electrophoretic mobility shift assays and western blot analysis. Functional validation was performed by measuring the inhibitory effects of DDE on neutrophil migration in vitro. DDE reduced the expression of IL-6 and IL-8 stimulated by PA-LPS in NPDFs. The activation of ERK1/2, Akt and NF-κB by PA-LPS was inhibited by DDE. Inhibitors of ERK1/2, Akt and NF-κB inhibited the expression of IL-6 and IL-8. In addition, DDE significantly attenuated PA-LPS-induced migration of differentiated HL-60 cells. The present findings suggest that DDE potently inhibits inflammation through the ERK1/2, Akt and NF-κB signaling pathways in NPDFs.

Evidence for a dynamic role for mononuclear phagocytes during endometrial repair and remodelling

In women, endometrial breakdown, which is experienced as menstruation, is characterised by high concentrations of inflammatory mediators and immune cells which account for ~40% of the stromal compartment during tissue shedding. These inflammatory cells are known to play a pivotal role in tissue breakdown but their contribution to the rapid scarless repair of endometrium remains poorly understood. In the current study we used a mouse model of menstruation to investigate dynamic changes in mononuclear phagocytes during endometrial repair and remodelling. Menstruation was simulated in MacGreen mice to allow visualisation of CSF1R⁺ mononuclear phagocytes. Immunohistochemistry revealed dynamic spatio-temporal changes in numbers and location of CSF1R-EGFP⁺ cells and Ly6G⁺ neutrophils. Flow cytometry confirmed a striking increase in numbers of GFP⁺ cells during repair (24 h): influxed cells were 66% F4/80⁺Gr-1⁺ and 30% F4/80⁻Gr-1⁺. Immunostaining identified distinct populations of putative ‘classical’ monocytes (GFP⁺F4/80⁻), monocyte-derived macrophages (GFP⁺F4/80⁺) and a stable population of putative tissue-resident macrophages (GFP^-F4/80⁺) localised to areas of breakdown, repair and remodelling respectively. Collectively, these data provide the first compelling evidence to support a role for different populations of monocytes/macrophages in endometrial repair and provide the platform for future studies on the role of these cells in scarless healing.

The adolescent transition under energetic stress: Body composition tradeoffs among adolescent women in The Gambia

BACKGROUND AND OBJECTIVES

Life history theory predicts a shift in energy allocation from growth to reproductive function as a consequence of puberty. During adolescence, linear growth tapers off and, in females, ovarian steroid production increases. In this model, acquisition of lean mass is associated with growth while investment in adiposity is associated with reproduction. This study examines the chronological and developmental predictors of energy allocation patterns among adolescent women under conditions of energy constraint.

METHODOLOGY

Fifty post-menarcheal adolescent women between 14 and 20 years old were sampled for weight and body composition at the beginning and end of 1 month in an energy-adequate season and 1 month in the subsequent energy-constrained season in a rural province of The Gambia.

RESULTS

Chronologically and developmentally younger adolescent girls gain weight in the form of lean mass in both energy-adequate and energy-constrained seasons, whereas older adolescents lose lean mass under conditions of energetic stress (generalized estimating equation (GEE) Wald chi-square comparing youngest tertile with older two tertiles 9.750, P = 0.002; GEE Wald chi-square comparing fast- with slow-growing individuals for growth rate 19.806, P < 0.001). When energy is limited, younger adolescents lose and older adolescents maintain fat (GEE Wald chi-square for interaction of age and season 6.568, P = 0.010; GEE Wald chi-square comparing fast- with slow-growing individuals for interaction of growth rate and season 7.807, P = 0.005).

CONCLUSIONS AND IMPLICATIONS

When energy is constrained, the physiology of younger adolescents invests in growth while that of older adolescent females privileges reproductively valuable adipose tissue.

Vascular dysfunction as a cause of endometrial bleeding

INTRODUCTION

Heavy menstrual bleeding (HMB) and the spotting and bleeding (S/B) associated with the use of hormonal contraceptives are distinct entities affecting endometrial vasculature and hemostasis.

MATERIALS AND METHODS

An overview of the major etiologies and potential treatments for each condition is provided.

RESULTS

HMB is potentially caused by several different hemostatic dysfunctions. Combination oral contraceptives, levonorgestrel-releasing intrauterine system, non-steroidal anti-inflammatory drugs, and anti-fibrinolytics all have been shown to have some degree of efficacy in treating HMB. The basic cause of HMB is unknown in the majority of cases. Endometrial S/B related to hormonal contraceptives is a common occurrence and may well have a common etiology in altered angiogenesis resulting in abnormal blood vessels with fragile vessel walls. There is no effective treatment for this problem.

CONCLUSIONS

Medical therapy for HMB is limited and effective for reducing blood loss during menstruation. There is no effective treatment for the S/B associated with hormonal contraceptives.

Endometrial chemokines, uterine natural killer cells and mast cells in long-term users of the levonorgestrel-releasing intrauterine system

OBJECTIVE

The objective was to assess endometrial chemokines in users of the levonorgestrel-releasing intrauterine system (LNG-IUS) and correlate them with leucocyte populations, uterine natural killer cells (uNK) and mast cells (MCs).

MATERIALS AND METHODS

Endometrium was obtained from two groups of women who had been using LNG-IUS for 3 years or more: 11 amenorrhoeic women formed the non-bleeding group and 15 women who maintained some form of cyclic bleeding comprised the bleeding group. Specific antibodies were used for the assessment of neutrophils, uNK cells and MCs. Immunohistochemistry was performed to locate the chemokines 6Ckine and interleukin-8 (IL-8).

RESULTS

Neutrophils were few and without differences between the two groups. uNK cells were significantly higher in the bleeding group (P < 0.0001). There was no difference between the total number of MCs and activated MCs, but there was a greater extracellular area stained for MC tryptase (P < 0.05). Chemokines 6CKine and IL-8 were abundant in the stroma and in the epithelium, and there was no difference between the groups.

CONCLUSIONS

We observed more uNK cells in users with bleeding and a greater extracellular area stained for MC tryptase, although there were no differences between the number of MCs and activated MCs or the chemokines 6CKine and IL-8. uNK cells and MC products may play a role in provoking breakthrough bleeding in long-term users of the LNG-IUS.

The effects of progesterone on matrix metalloproteinases in cultured human gingival fibroblasts

BACKGROUND

Although pregnancy gingivitis is widely believed to result from elevated hormone concentrations, the mechanism(s) involved in the etiology of this condition remain unknown. Paradoxically, despite the apparent inflammation for a prolonged period, pregnancy gingivitis rarely progresses to periodontitis and usually resolves postpartum. We used several methods to test in vitro the hypothesis that the elevated progesterone levels of pregnancy might inhibit the production of some of the matrix metalloproteinases (MMPs) that are responsible for periodontal destruction.

METHODS

Cultured human gingival fibroblasts (GF) were tested in phenol red-free, serum-free medium with or without the progestogen, medroxyprogesterone acetate (MPA; 10(-6) M), using interleukin-1beta (IL-1beta) to initiate immune responses and MMP production. These MMP responses were examined by macroarrays, reverse transcription-polymerase chain reaction (RT-PCR), zymograms, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Array analysis showed that pretreatment of GF with MPA reduced mRNA induction for MMPs-1, -3, and -10 in response to 6 to 8 hours incubation with IL-1beta. RT-PCR confirmed, that after 24 hours with IL-1beta , GF pretreated with MPA had undetectable levels of mRNA for MMPs-1, -2, -3, -7, -10, and -13. Zymograms of culture media from this 24-hour period showed reduction in several proteolytic activities. Examination of such 24-hour media using ELISA for MMP-3 and pro-MMP-13 confirmed that secretion of these enzymes was upregulated by IL-1beta and modulated downward by pretreatment with MPA.

CONCLUSIONS

Production by GF of numerous MMPs in response to IL-1beta was significantly reduced by progesterone. This steroidal modulation of proteolytic enzymes could help to explain why pregnancy gingivitis typically is not characterized by progression to periodontitis.

Progesterone inhibits activation of latent matrix metalloproteinase (MMP)-2 by membrane-type 1 MMP: enzymes coordinately expressed in human endometrium

Matrix metalloproteinases (MMP) have specific spatial and temporal expression patterns in human endometrium and are critical for menstruation. Expression and activation mechanisms for proMMP-2 differ from other MMPs; in many cells proMMP-2 is specifically activated by membrane-type (MT)-MMPs. We examined the expression and localization of proMMP-2, MT1-MMP, and MT2-MMP in human endometrium across the menstrual cycle; and we examined the expression of MT1-MMP and activation of proMMP-2 in cultured endometrial stromal cells and their regulation by progesterone. MMP-2 was immunolocalized in 25 of 32 endometrial samples in all cellular compartments but with greatest intensity in degrading menstrual tissue. MT1-MMP mRNA was present throughout the cycle, and immunoreactive protein was detected in 24 of 32 samples, with the strongest staining in subsets of macrophages, neutrophils, and granular lymphocytes (but not mast cells or eosinophils) during the menstrual, mid-proliferative and mid-secretory phases. Patchy epithelial staining and staining of decidual cells, often periglandular in menstrual tissue, were also seen. MT2-MMP was more widespread than MT1-MMP without apparent cyclical variation and with maximal intensity in glandular epithelium. Cultured endometrial stromal cells released proMMP-2, and progesterone treatment significantly reduced the percentage level of its active (62 kDa) form (22.5 +/- 1.8% vs. 3.0 +/- 1.3%, without and with treatment, respectively, mean +/- SEM, P < 0.0001). This activation was blocked by a specific MMP inhibitor and restored following inhibitor removal. Progesterone also attenuated cell expression of MT1-MMP mRNA. We postulate that MT1-MMP activates proMMP-2 in endometrium, this activity being increased at the end of the cycle when progesterone levels fall, thus contributing to menstruation.

Menstruation: induction by matrix metalloproteinases and inflammatory cells

Menstruation occurs at the end of a normal reproductive cycle in the human female, following the fall in progesterone resulting from the demise of the corpus luteum. Current data support a central role for the matrix metalloproteinases in menstruation but their focal pattern of expression within peri-menstrual and menstrual endometrium suggests local rather than hormonal regulation. This review emphasizes the similarities between menstruation and an inflammatory process and examines the relationship between cells of hemopoietic lineage, particularly mast cells, eosinophils, neutrophils and macrophages, and the local production and activation of matrix metalloproteinases within the endometrium. It proposes a complex of critical regulatory circuits, initially activated by the withdrawal of progesterone, which provide interactions between the migratory cells that produce a myriad of important regulatory molecules and endometrial stromal and epithelial cells which produce both chemokines and matrix metalloproteinases. These mechanisms could account for the focal nature of the tissue degradation at menstruation.