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Search for other papers by Emmanuel Amabebe in
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Graphical abstract
Abstract
The phenomenal extracellular matrix (ECM) remodelling of the cervix that precedes the myometrial contraction of labour at term or preterm appears to share some common mechanisms with the occurrence, growth, invasion and metastasis of cervical carcinoma. Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that are pivotal to the complex extracellular tissue modulation that includes degradation, remodelling and exchange of ECM components, which contribute to homeostasis under normal physiological conditions such as cervical remodelling during pregnancy and puerperium. However, in cancer such as that of the uterine cervix, this extensive network of extracellular tissue modulation is altered leading to disrupted cell–cell and cell–basement membrane adhesion, abnormal tissue growth, neovascularization and metastasis that disrupt homeostasis. Cervical ECM remodelling during pregnancy and puerperium could be a physiological albeit benign neoplasm. In this review, we examined the pathophysiologic differences and similarities in the role of MMPs in cervical remodelling and cervical carcinoma.
Lay summary
During pregnancy and childbirth, the cervix, which is the barrel-shaped lower portion of the womb that connects to the vagina, gradually softens, shortens and opens to allow birth of the baby. This process requires structural and biochemical changes in the cervix that are stimulated by enzymes known as matrix metalloproteinases. Interestingly, these enzymes also affect the structural and biochemical framework of the cervix during cervical cancer, although cervical cancers usually occur after infection by human papillomavirus. This review is intended to identify and explain the similarities and differences between the structural and chemical changes in the cervix during pregnancy and childbirth and the changes seen in cervical cancer.
Search for other papers by Noble K Kurian in
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Search for other papers by Deepak Modi in
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Group B Streptococcus (GBS) is an opportunistic pathogenic bacterium which upon colonization in the female reproductive tract can cause preterm births, fetal injury, and demise. Several determinants for GBS pathogenesis have been explored so far through the studies using animal models ranging from mice to non-human primates. The results from these experimental data have identified outer membrane vesicles, β-hemolysin, hyaluronidase, and Cas9 of GBS as major virulence factors leading to preterm births. Most of these factors drive inflammation through activation of NLRP3 and elevated production of IL1-β. However, the absence of one of the factors from the pathogen reduces but does not completely abolish the pathogenesis of GBS suggesting the involvement of more than one factor in causing preterm birth. This makes further exploration of other virulence factors of GBS pathogenesis important in gaining an insight into the mechanistic basis of GBS-mediated preterm births.
Lay summary
Group B Streptococcus (GBS) is a pathogenic bacteria whose infection in the reproductive tract during pregnancy can cause premature delivery. This bacterial infection is one of the major causes of death of mother and baby during pregnancy, and the bacteria is prevalent in all parts of the world. This makes the research on GBS so important and many of the mechanisms behind GBS infection during pregnancy still remain unexplored. In this review, we have outlined how various animal models contributed in finding the mechanism of GBS pathogenesis. The review also focuses on compiling various virulence factors which makes GBS pathogenic in the vulnerable. Understanding the mechanisms of infection by GBS will be crucial in developing drugs and vaccines to protect against the harmful effects of the bacteria.
Search for other papers by Carlos H Miyashira in
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Search for other papers by Fernanda Reali Oliveira in
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Gynecologic Division, BP – A Beneficencia Portuguesa de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
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Search for other papers by Julian A Gingold in
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Gynecologic Division, BP – A Beneficencia Portuguesa de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
Search for other papers by Mauricio Simões Abrão in
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The objective of this study was to systematically review the literature on the human microbiome in association with endometriosis. PubMed/Medline, Cochrane, and Embase databases were searched for literature published from 1986 to August 2021. All human studies that assessed the microbiome using 16S rRNA sequencing or shotgun sequencing in women with endometriosis were included. Two reviewers independently abstracted data from the selected articles into tables. To assess the quality of included studies, the National Institutes of Health Study Quality Assessment Tools were utilized. This review included 12 case–control studies. Included studies compared the microbiome from various anatomical sources (fecal, vaginal, cervical, peritoneal, endometrial, and intra-lesional) between patients with endometriosis and a heterogeneous set of control patients. Study quality ranged from poor to good, with 8 of 12 studies rated fair. Multiple studies reported a different distribution of bacteria among women with endometriosis across anatomical sites, but the results were highly heterogeneous. Pseudomonas was overrepresented in peritoneal fluid among women with endometriosis across multiple studies but was also observed to be increased in vaginal, endometrial, and intra-lesional samples. Among bacteria noted across different anatomical samples, Gardnerella was found to be increased in cervical but decreased in endometrial, fecal, and vaginal samples of patients with endometriosis, while Atopium was found to be decreased in vaginal and cervical samples from patients with endometriosis. Sphingobium was found to be increased in vagina, endometrium, and peritoneal fluid from patients with endometriosis. Streptococcus was found to be increased in peritoneal, endometrial, and cervical samples from women with endometriosis. Microbiomal comparisons stratified by endometriosis stage or site of endometriosis involvement were limited and highly heterogeneous.
Lay summary
The microbiome, a group of bacteria found in a particular place in the body, has been shown to vary when patients have some diseases, such as cancer or inflammatory bowel disease. Less is known about the microbiome in patients with endometriosis. This review looked at existing studies comparing the bacteria found in patients with endometriosis and others without. Twelve studies were found that assessed the bacteria from swabs collected from different places, including the vagina, cervix, endometrium, peritoneum, feces, and endometriosis lesions themselves. Most of the studies found higher or lower levels of specific bacteria at each of these places, but the findings were often inconsistent. The findings were probably limited by the small numbers of patients involved and variations in the groups studied. More research is needed to find out which bacteria are over- and underrepresented in patients with endometriosis and where they are found.
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Juno Genetics, Winchester House, Oxford, UK
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Abstract
Mitochondrial quality is implicated as a contributor to declining fertility with aging. We investigated mitochondrial transcripts in oocytes and their associated cumulus cells from mice of different ages using RNA-seq. Mice aged 3 weeks, 9 weeks, and 1 year were superovulated, and 48 h later, oocyte cumulus complexes were collected by follicle puncture. We did not detect any major differences that could be attributed to aging. However, mitochondrial RNA transcripts which deviated from the consensus sequence were found at a higher frequency in cumulus cells than in their corresponding oocyte. Previous investigations have shown that variation in the sequence of mtRNA transcripts is substantial, and at least some of this can be accounted for by post-transcriptional modifications which impact base calling during sequencing. Our data would be consistent with either less post-transcriptional modification in mitochondrial RNA from oocytes than cumulus cells or with lower mtDNA mutational load.
Lay summary
Women become less fertile as they age. Shortage of energy contributes to this, caused by a decline in the quality of mitochondria (the powerhouses of the cell) in the egg. Genes are the blueprint for the cell. They are made of DNA which is copied into an RNA message, or instructions, for making proteins. We counted differences in the RNA message of developing eggs and the cells that support them during development (cumulus cells). We compared the number of these differences in mice of different ages. These age groups represent mice had not reached puberty, those of prime reproductive age, and old mothers. We did not find any differences linked to the age of the mice. However, we did find differences between the egg and the cumulus cells. In most cases, there were lower levels of mutations in eggs than there were in cumulus cells.
Search for other papers by Kirsten S Wilson in
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Leibniz Institute for Zoo and Wildlife Research, Department Reproduction Biology, Berlin, Germany
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Graphical abstract
Abstract
Giant pandas are mono-estrus seasonal breeders, with the breeding season typically occurring in the spring. Successful fertilization is followed by an embryonic diapause, of variable length, with birth in the late summer/autumn. There is a need for additional understanding of giant panda reproductive physiology, and the development of enhanced biomarkers for impending proestrus and peak fertility. We aimed to determine the utility of non-invasive androgen measurements in the detection of both proestrus and estrus. Urine from 20 cycles (−40 days to +10 days from peak estrus) from 5 female giant pandas was analyzed for estrogen, progestogens and androgens (via testosterone and DHEA assays), and hormone concentrations were corrected against urinary specific gravity. Across proestrus, estrogens increased while progestogens and androgens decreased – at the point of entry into proestrus, androgens (as detected by the testosterone assay) decreased prior to progestogens and gave 4 days advanced warning of proestrus. At the time of peak estrus, androgens (as detected by the DHEA assay) were significantly increased at the time of the decrease in estrogen metabolites from the peak, acting as an alternative confirmatory indicator of the fertile window. This novel finding allows for enlargement of the preparative window for captive breeding and facilitates panda management within breeding programmes. Androgens allow an enhanced monitoring of giant panda estrus, not only advancing the warning of impending proestrus, but also prospectively identifying peak fertility.
Lay summary
Giant pandas have one chance at pregnancy per year. The 2-day fertile window timing varies by year and panda. This is monitored by measuring the level of estrogens in the urine, which increase, indicating an upcoming fertile period. After 1–2 weeks of increase, estrogens peak and fall, marking the optimal fertile time. We tested other hormones to see if we can predict the fertile window in advance, and the specific fertile time with more accuracy. In 20 breeding seasons from 5 females, we found androgens, usually thought of as male hormones, had an important role. Testosterone gives 4 days advanced warning of estrogens increasing. DHEA identified peak estrogen and the fertile time before needing to see a confirmed decrease in estrogen itself. Therefore, androgens help improve monitoring of the giant panda breeding season, giving early warning of fertility, key in facilitating captive breeding and giant panda conservation.
Search for other papers by Yoshinobu Ichikawa in
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Shizuoka Institute for the Study of Marine Biology and Chemistry, Shizuoka University, Shizuoka City, Shizuoka, Japan
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Abstract
During fertilization, avian sperm preferentially penetrate into the perivitelline membrane that covers the germinal disk region where the female nucleus is present. This phenomenon has been observed not only in domestic birds but also in wild birds; however, the mechanisms controlling sperm preference are still unclear. In this study, we investigated the possible involvement of annexin family protein in sperm–egg interaction in Japanese quail. Microscopic examination of fertilized eggs indicated that quail sperm penetration only occurred in the germinal disk region, and sperm localized outside the germinal disk were trapped in the perivitelline membrane. Western blot analysis and immunofluorescence microscopy revealed the presence of annexin A1 and A6 in the oocyte membrane, while annexin A6 localized in the perivitelline space of the germinal disk region. Further, our sperm binding assay using recombinant annexin A6 demonstrated that ejaculated sperm specifically bound to annexin A6 expressed in mammalian cell lines. These results suggest that annexin A6, which is expressed on the surface of oocytes, may function in sperm–egg interaction in the germinal disk region and that this binding may ensure sperm retention on the surface of the egg plasma membrane until fertilization takes place in Japanese quail.
Lay summary
In bird species, fertilization takes place immediately after ovulation of the egg. Sperm preferentially penetrate a specific area of the egg coating that covers the ‘germinal disk region’ – this area contains the cell that needs to be fertilized by a sperm. However, since the bird egg is extremely large in size and sperm must reach the ‘germinal disk region’ to achieve fertilization, it is unclear how this happens. Annexin proteins support fertilization in mammals, and we found that annexin A6 protein exhibits a unique localization in the germinal disk region in the eggs of Japanese quail. To test this interaction, we incubated quail sperm with cells that produced annexin A6 and found that ejaculated sperm bound to the cells. These results suggest that annexin A6 may have a role in the sperm–egg interaction in the germinal disk region in Japanese quail.
Search for other papers by Roseanne Rosario in
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The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia
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Search for other papers by Richard A Anderson in
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Unlike traditional chemotherapy agents which are generally cytotoxic to all cells, targeted anti-cancer therapies are designed to specifically target proliferation mechanisms in cancer cells but spare normal cells, resulting in high potency and reduced toxicity. There has therefore been a rapid increase in their development and use in clinical settings, including in curative-intent treatment regimens. However, the targets of some of these drugs including kinases, epigenetic regulatory proteins, DNA damage repair enzymes and proteasomes, have fundamental roles in governing normal ovarian physiology. Inhibiting their action could have significant consequences for ovarian function, with potentially long-lasting adverse effects which persist after cessation of treatment, but there is limited evidence of their effects on reproductive function. In this review, we will use literature that examines these pathways to infer the potential toxicity of targeted anti-cancer drugs on the ovary.
Lay summary
Compared to traditional chemotherapy agents, anti-cancer therapies are thought to be highly effective at targeting cancer cells but sparing normal cells, resulting in reduced drug side effects. However, many of processes within the cells that these drugs affect are also important for the ovary to work normally, so suppressing them in this way could have long-lasting implications for female fertility. This review examines the potential toxicity of anti-cancer therapies on the ovary.
Program of Ethics and Public Policies in Human Reproduction, Universidad Diego Portales, Santiago, Chile
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Search for other papers by Juan F Montiel in
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Premature ovarian insufficiency (POI) affects 1-3% of women under 40 years of age. The identified causes are highly heterogeneous, and 70% of the cases are idiopathic. The ovarian manifestation varies from a variable population of follicles that fail to develop (follicular POI) to the absence of follicles (afollicular POI) with a transition from one to the other over time. Previously, we have described a mouse model of POI that results from an oocyte-specific deletion of N- and O-glycans; Double Mutant (DM). DM females produce only one litter before undergoing POI due to ovarian dysfunction. In this study, we have characterised the gene expression profile of prepuberal (3 weeks), fertile (6 weeks) and infertile (9 weeks) DM ovaries. Up-regulation of cathepsin K (Ctsk, with unknown ovarian function) seems to trigger transcriptional changes in DM ovaries. Significant transcriptional changes then occur rapidly, associated with morphophysiological changes displayed by DM mice throughout the onset of POI. We identified genetic pathways such as extracellular matrix and immune response as candidates for the onset of POI in DM females. Remarkably, DM mice and POI women share a set of differentially expressed genes, including a functionally and co-expressed network of Mcm (minichromosome maintenance proteins) family members. The transcriptomic profile of the DM mouse model provides novel insight into the aetiology of POI.
Lay summary
Problems in ovary function lead to reduced fertility or infertility. One such condition is premature ovarian insufficiency (POI) which affects 1% of women under 40 years of age, and in over 70% of these, the cause of POI is unknown. To investigate POI, we have developed a mouse model. These mice are initially fertile but develop POI by 3 months of age. In this study, we investigated the changes in genes activated in the ovaries during the transition from fertility to POI, and we did this by comparing them to normal mice; gene activation leads to molecule production. A molecule known as cathepsin K seems to trigger changes during the onset of POI, followed by others related to structure and immune response pathways. In addition, some genes were identified that are similar between the POI mice and POI women.
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IMT International Limited, Tattenhall, Chester, UK
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Chester Zoo, Upton-by-Chester, UK
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Search for other papers by Christina Hvilsom in
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Biodiversity is defined as the presence of a variety of living organisms on the Earth that is essential for human survival. However, anthropogenic activities are causing the sixth mass extinction, threatening even our own species. For many animals, dwindling numbers are becoming fragmented populations with low genetic diversity, threatening long-term species viability. With extinction rates 1000–10,000 times greater than natural, ex situ and in situ conservation programmes need additional support to save species. The indefinite storage of cryopreserved (−196°C) viable cells and tissues (cryobanking), followed by assisted or advanced assisted reproductive technology (ART: utilisation of oocytes and spermatozoa to generate offspring; aART: utilisation of somatic cell genetic material to generate offspring), may be the only hope for species’ long-term survival. As such, cryobanking should be considered a necessity for all future conservation strategies. Following cryopreservation, ART/aART can be used to reinstate lost genetics back into a population, resurrecting biodiversity. However, for this to be successful, species-specific protocol optimisation and increased knowledge of basic biology for many taxa are required. Current ART/aART is primarily focused on mammalian taxa; however, this needs to be extended to all, including to some of the most endangered species: amphibians. Gamete, reproductive tissue and somatic cell cryobanking can fill the gap between losing genetic diversity today and future technological developments. This review explores species prioritisation for cryobanking and the successes and challenges of cryopreservation and multiple ARTs/aARTs. We here discuss the value of cryobanking before more species are lost and the potential of advanced reproductive technologies not only to halt but also to reverse biodiversity loss.
Lay summary
The world is undergoing its sixth mass extinction; however, unlike previous events, the latest is caused by human activities and is resulting in the largest loss of biodiversity (all living things on Earth) for 65 million years. With an extinction rate 1000–10,000-fold greater than natural, this catastrophic decline in biodiversity is threatening our own survival. As the number of individuals within a species declines, genetic diversity reduces, threatening their long-term existence. In this review, the authors summarise approaches to indefinitely preserve living cells and tissues at low temperatures (cryobanking) and the technologies required to resurrect biodiversity. In the future when appropriate techniques become available, these living samples can be thawed and used to reinstate genetic diversity and produce live young ones of endangered species, enabling their long-term survival. The successes and challenges of genome resource cryopreservation are discussed to enable a move towards a future of stable biodiversity.
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Lay summary
Endometriosis is a benign disease that can cause pain and infertility in women. Debate exists over how endometriosis should best be diagnosed. On one hand, endometriosis can be diagnosed by directly examining pelvic anatomy via a surgical procedure known as diagnostic laparoscopy. On the other hand, the disease can be diagnosed via non-surgical means such as using medical imaging, the symptoms described by the patient and whether the patient responds to non-surgical therapies such as medication. In this debate article, we argue in favour of diagnostic laparoscopy. We review the safety of the procedure, compare the ability of diagnostic laparoscopy vs medical imaging to detect endometriosis and consider the benefits of formally diagnosing or ruling out the condition.
