Allergic diseases affect up to one third of the world’s population, and their prevalence is on the increase. In order to develop more targeted and effective therapies, research is mobilizing to better understand the biological and cell mechanisms involved in the onset of allergies. Mast cells – a type of immune cell – is of particular interest to scientists and doctors, but there is little data about them at present. In a new study published in Journal of Experimental Medicine in July 2023, researchers from Inserm, CNRS and Université Toulouse III – Paul-Sabatier, at the Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), broadened our understanding of these cells and created the first digital mapping of mast cells in humans. These findings open up avenues for the adaptation of therapeutic strategies.
Allergic diseases are a major public health problem, to the extent that the World Health Organization (WHO) has classified allergy as being the world’s fourth leading chronic disease. It is currently estimated that 25 to 30% of the population suffers from an allergy, be it food, skin or respiratory allergy, and this proportion could increase to 50% by 2050. A better understanding of the underlying biological mechanisms is a key step if we are to develop more targeted and effective therapies.
This is the goal of Inserm researcher Nicolas Gaudenzio and his team at the Toulouse Institute for Infectious and Inflammatory Diseases. In 2019, the scientists had published a first article in Nature Immunology, showing the crucial role played by immune cells known as “mast cells” in the initiation of eczema. This research has given rise to new therapies that are currently in development.
Mast cells remain poorly understood by scientists. We know that their functions go far beyond problems of allergies and that they can have roles that are either beneficial (such as in fighting bacteria) or not, depending on the pathology. Research has also led to their classification into two large families of mast cells: the CTMCs found mainly in the skin and the MMCs located mainly in the gut mucosa.
However, much remains to be learned about these cells that are complex to study, especially because it is difficult to extract them from tissue.
“If we are to understand how we can act on mast cells and block their harmful action in terms of allergic diseases, we need to improve our knowledge of these cells. This involves determining their location, if there are several types beyond the dichotomy which has traditionally been described, and whether their functions differ according to the tissues in which they are located,” points out Gaudenzio.
In this new study, the research team used more recent technologies to study mast cells more precisely in mice and humans. The scientists used the single-cell sequencing technique: they sequenced the RNA of individual cells from several organs in order to extract their individual “identity card”.
Analyzing human cells with this method reveals a much more complex image than has hitherto been described. Indeed, the cells of over thirty human organs were analyzed thanks to advanced techniques for exploring data banks and bioinformatics. The researchers thus identified not two but seven different subtypes of mast cells, with various characteristics and functions.
From this data, the team was able to create and enable open access to the first “digital mapping” of human mast cells, which allows any scientist to see at a glance which mast cell subtype is associated with which organ and learn more about its function.
This diagram shows, in a simplified way, the distribution of the different mast cell subtypes through different organs of the body.
This approach represents a major paradigm shift since the new mapping makes it possible, just by querying a database, to better understand the natural diversity of mast cells in allergic diseases, and thus open up a process of reflection on the need to adapt therapies to more precisely target the cell subtypes involved.
“This study is the first foundation stone of a vast building that is expected to transform the anti-allergy therapies and move towards a greater personalization of treatments, with more efficacy and fewer side effects. We will continue to supplement this mapping by studying mast cells in different disease settings, in treated and untreated patients alike, so that it is as precise as possible for the scientific and medical community that is working on allergies,” concludes Gaudenzio.
For the first time, researchers from Institut Curie, the CNRS and Inserm have uncovered a previously unknown chain of biochemical reactions. This chain involves copper and leads to metabolic and epigenetic alterations[1] that activate inflammation and tumorigenesis. But there is more; the research team developed a “drug prototype” capable of mitigating both the mechanisms of inflammation and the processes potentially involved in metastatic spread. Published in the journal Nature on April 26, 2023, these results provide hope for new therapeutic opportunities to control inflammation and cancer.
Inflammation is a complex biological process that can eradicate pathogens and promotes repair of damaged tissues. However, deregulation of the immune system can lead to uncontrolled inflammation and produce lesions instead. Inflammation is also involved in cancer. The molecular mechanisms underlying inflammation are not fully understood, and so developing new drugs represents a significant challenge.
As far back as 2020, Dr. Raphaël Rodriguez, CNRS research director and head of the Chemical Biology team at Institut Curie (Equipe Labellisé Ligue Contre le Cancer) at the Cellular and Chemical Biology laboratory (Institut Curie/CNRS/Inserm), had shed new light on a membrane receptor called CD44, which marks immune responses, inflammation and cancer progression. Dr. Rodriquez and his team showed that CD44 helped import iron into cell[2], triggering a series of reactions leading to activation of genes involved in the metastatic process.
“This is a cell plasticity phenomenon we continued to study, investigating other metals potentially internalized by CD44, notably copper,” he explains.
Copper causing epigenetic alterations
Along with his colleagues[3], Dr. Rodriguez has now reached a new milestone.
The research team managed to identify a signaling pathway involving copper and leading to the expression of pro-inflammatory genes in macrophages, the cells present in all tissues and playing an important role in innate immunity.
Once internalized in macrophages, copper enters into the mitochondria (the organelle responsible for cell respiration and energy production), where it catalyzes the oxidation of NADH into NAD+ (nicotinamide adenine dinucleotide, a molecule needed for the activity of certain enzymes). The increase of NAD+ in cells enables the activity of certain enzymes involved in the production of metabolites essential for epigenetic regulation. These metabolites thus, contribute to the activation of genes involved in inflammation.
Inflammation and cancer: shared molecular mechanisms
The scientists did not stop there, they also designed molecules able to bind to copper, inspired from the structure of metformin.[4] By testing these new molecules on models of acute inflammation, they found that a synthetic dimer of metformin, LCC-12 (also termed Supformin), reduced activation of macrophages and attenuated inflammation.
“Our work has enabled us to develop a drug prototype that inactivates copper chemistry in the cell’s metabolic machinery, thus blocking expression of the genes involved in inflammation”, explains Dr. Rodriguez.
To finish, they applied this therapeutic strategy to cancer cell models engaged in an epithelial-mesenchymal transition[5]. Here again, Supformin blocked the cellular mechanism and thus the cell transformation.
“The genes activated in cancer cells are not the same as those expressed in immune cells, but the chain reaction leading to epigenetic alterations is identical”, explains Dr. Rodriguez.
These results thus reveal the role of copper in cancer cells and their ability to adopt a metastatic nature.
Dr. Raphaël Rodriguez concludes: “Our study reveals that the inflammatory and cancer processes depend on similar molecular mechanisms and could therefore in the future benefit from similar innovative therapies, such as those tested with Supformin.”
The explanations of Dr. Raphaël Rodriguez in video :
[1]Epigenetics is the study of the mechanisms at play in gene regulation, which is essential to the action of cells and to maintaining their identity. Unlike genetic mutations, which are permanent, epigenetic modifications on DNA or histones are reversible.
[3] This study was conducted at Institut Curie, in the Cellular and Chemical Biology unit (Institut Curie, CNRS, Inserm), in collaboration with UVSQ, Raymond Poincaré hospital (AP-HP), Gustave Roussy hospital, the Institut de chimie moléculaire et des matériaux d’Orsay (CNRS/University Paris-Saclay), the Multimodal Imaging Center (CNRS/Institut Curie/Inserm/University Paris-Saclay), the Center for Infection and Immunity of Lille (CNRS/Inserm/Institut Pasteur de Lille/CHU of Lille/University of Lille), Institute of Pharmacology and Structural Biology (CNRS/University of Toulouse III) along with British and Australian researchers.
[4]Metformin is a treatment used for Type-2 diabetes, and is able to form a bimolecular complex with copper.
[5] Epithelial-mesenchymal transition is the first step in enabling cancer cells to metastasize.
The process of aging is often related to the onset of cognitive decline, depression and memory loss. Scientists from the Institut Pasteur, CNRS and Inserm have discovered that administration of the GDF11 protein, which is known to regenerate murine neural stem cells, improves cognitive abilities and reduces the depressive state in aged mice. They also demonstrated the mechanism of action of this protein in different mouse models. The scientists then investigated these results further in relation to depression, and showed that in humans, the levels of GDF11 are inversely related to depressive episodes. The results of this study were published in the journal Nature Aging on February 2, 2023.
The process of aging is often related to the onset of neurological symptoms such as cognitive decline, memory loss or mood disorders such as depression. Previous studies have shown that the growth factor GDF11, a protein found in blood, has a beneficial effect on olfactory perception and on the generation of new cells in the brains of aged mice. The mechanism of action of GDF11 in the brain remained unknown.
Researchers from the Institut Pasteur, CNRS and Inserm have discovered that long-term administration of the GDF11 protein to aged mice improves their memory and significantly reduces behavioral disturbances related to depression, allowing them to return to a behavior similar to that seen in younger mice.
The scientists conducted further studies in different aged mouse models or mouse models with depression-like behavioral disorders and in vitro neuronal cultures, which enabled them to identify the molecular mechanism of action of GDF11. They discovered that administration of GDF11 activates the natural process of intracellular cleaning, called “autophagy”, in the brain and the elimination of senescent cells. The GDF11 protein thus indirectly increases cell turnover in the hippocampus and restores neuronal activity.
To better understand the link between depressive disorders and the GDF11 protein in humans, scientists from the Institut Pasteur, CNRS and Inserm, in collaboration with scientists from McMaster University, quantified the protein in the blood serum of an international cohort of young patients with major depressive disorder. They observed that GDF11 levels are significantly lower in these patients. Moreover, by measuring the levels of this protein at different stages, the scientists observed a fluctuation in the level depending on the depressive state.
“This work provides clinical evidence linking low blood levels of GDF11 to mood disorders in patients with depression,” said Lida Katsimpardi, a researcher in the Institut Pasteur’s Perception and Memory Unit, affiliated with Inserm at the Institut Necker-Enfants Malades, and co-last author of the study. “In the future, this molecule could be used as a biomarker to diagnose depressive episodes. It could also serve as a therapeutic molecule for the treatment of cognitive and affective disorders,” she concludes.
Emulsifiers are food additives that are used to improve texture and extend shelf life. They are found in many processed products (ice cream, packaged cakes, sauces, etc.) despite having demonstrated harmful effects on intestinal balance. In a new study, scientists from Inserm, CNRS and Université Paris Cité at Institut Cochin in Paris sought to counteract these effects by using Akkermansia muciniphila, a bacterium naturally present in the intestine,to repopulate and thus strengthen the intestinal epithelium. The addition of this bacterium to the gut microbiota is thought to prevent the damage caused by the consumption of emulsifiers. These data, published in Gut, confirm the growing potential of Akkermansiamuciniphila as a probiotic.
Emulsifiers are consumed by millions of people every day and are among the most widely used additives in the food industry. Something that is not surprising given that they improve the texture of foods and extend their shelf life. For example, emulsifiers such as lecithin and polysorbates ensure the smooth texture of mass-produced ice cream and prevent it from melting too quickly once served.
Previous studies by the team of Benoît Chassaing, Inserm researcher at Institut Cochin (Inserm/CNRS/Université Paris Cité), have shown the consumption of certain emulsifiers to lead to alterations of the gut microbiota[1] and how it interacts with the digestive system. Such alterations lead to chronic gut inflammation and metabolic dysregulation. More specifically, this research has shown the consumption of food emulsifiers to induce the ability of certain elements of the microbiota to come into close contact with the epithelium, which is the first line of defense of the digestive tract and usually sterile.
In this new study, the researchers wanted to counteract the harmful effects caused by the consumption of emulsifiers by reinforcing the intestinal epithelium. To do this, they focused more specifically on the bacterium Akkermansia muciniphila, which, being naturally present in the intestine has already been shown to have an impact on the interactions of the microbiota with the rest of the body.
It is also known that the quantity of this bacterium is reduced when emulsifiers are consumed.
In the study, groups of mice were fed emulsifying agents as part of their diet, which for some of them was supplemented with a daily dose of Akkermansia muciniphila. The scientists saw that while the consumption of food emulsifiers was sufficient to induce the chronic inflammation associated with metabolic alterations and high blood glucose, the mice receiving Akkermansia muciniphila were totally protected against such effects. The administration of Akkermansia muciniphila was also sufficient in preventing all molecular alterations normally induced by the consumption of emulsifying agents, including the encroachment of bacteria into the wall of the epithelium.
“This research supports the notion that using Akkermansia muciniphila as a probiotic could be an approach to maintaining metabolic and intestinal health in the face of modern stressors such as emulsifiers that promote chronic gut inflammation, and the resulting harmful consequences. Furthermore, this suggests that colonization of the intestine with Akkermansia muciniphila could be predictive of individual propensity to develop intestinal and metabolic disorders following the consumption of emulsifiers: the greater the presence of the bacterium, the more likely the individual is protected from the harmful effects of food additives on the microbiota,” explains Chassaing, the last author of the study.
[1] All of the microorganisms – non-pathogenic (commensal) bacteria, viruses, parasites, and fungi – that live in the intestine.
Today, around 1 in 8 couples seek help because they are struggling to conceive. This is probably linked to the fact that couples are starting families later in life than before, or because they are setting aside the taboos linked to infertility and are more willing to seek help. Infertility has therefore become a public health problem, and the scientific community is rallying in response.
Where are we with research into this area, which lies at the heart of current societal problems? What are the prospects for the transfer of such research into clinical practice? Fertility research covers many different areas. The aim of this press kit is not to tackle them exhaustively, but to highlight the sectors in which research is making progress.
When research makes progress, everyone’s health benefits.
Research into combating infertility
The term infertility is used when a couple are unable to conceive a child naturally after 12 months of trying. This term covers cases of total sterility, where there is no hope of natural conception, and subfertility, the majority of cases, in which couples have a reduced – but not zero – chance of achieving a pregnancy.
Cases of infertility are divided into 4 categories based on their cause:
– 30% are female-related;
– 30% are male-related. In men, azoospermia and oligospermia are the two leading causes of infertility identified to date;
– 30% are combined, meaning that they are caused by reduced fertility in both partners;
– 10% are unexplained.
In women, with the exception of mechanical causes affecting the fallopian tubes – when they are impaired or blocked (usually following an infection) – or uterus, endometriosis and abnormal ovulation are the most common causes of infertility.
Causes of abnormal ovulation include polycystic ovary syndrome (which affects around 10% of women around the world), hyperprolactinemia, and primary ovarian insufficiency (which may also be a side effect of chemotherapy).
Current research seeks to both improve understanding of the causes of infertility, and also to study new therapies or management methods that aim to increase the chances of conception.
Improving understanding of the causes
The genetic approach
Many researchers are studying the genetic causes of ovarian insufficiency. Several fertility problems are caused by certain genes not working, or not working properly. One rapidly growing area of research, due in particular to the improvement in high-throughput screening methods, is the study of genetic variants.
The Inserm laboratory led by Nadine Binart, for example, is working on primary ovarian insufficiency (POI), which is characterized by the inability of ovarian follicles to mature or by diminished ovarian reserve. Based on DNA analysis of women with POI, researchers are working to isolate the genes that are involved or altered in their genetic make-up. This approach is helping to improve understanding of the disease, but does not make it possible to provide specific treatment to these women, as sterility becomes definitive once there are no more eggs left in their ovaries. Preventive management can however be introduced if the genetic abnormality is found before the ovarian reserve is entirely depleted – for example, during family testing. This is the role of clinical research, which makes it possible to lessen the impact of these diseases when mutations are identified in affected families, to inform young patients about the risk of losing their eggs over time, and to introduce fertility preservation methods if appropriate.
The hormonal approach: the example of kisspeptin and prolactin
It is well-established that breastfeeding results in increased secretion of prolactin (PRL) by the pituitary gland, inhibiting a woman’s ability to ovulate. This prevents the onset of a new pregnancy. Some diseases also lead to an increase in PRL, including tumors of the pituitary gland from which this hormone is secreted. These cases of hyperprolactinemia, which result in period problems and infertility, are a leading cause of anovulation. In 2011, the Inserm team led by Jacques Young and Nadine Binart revealed the underlying mechanism that blocks ovarian function. Using a mouse model of the disease, the researchers showed that PRL inhibits secretion of a neurohormone called kisspeptin, which is the starting point for the entire hormone cascade responsible for ovarian cyclicity. In a mouse model, administration of kisspeptin made it possible to restore ovarian cyclicity despite the hyperprolactinemia.
This pathophysiological discovery explains the link between infertility and hyperprolactinemia for the first time, and points the way to developing innovative therapies. The basic concept has recently been validated in women,[1] which will make it possible to offer a therapeutic alternative for patients who do not respond to the drugs currently used.
1.2. Preserving fertility: areas of research and latest findings
Specialist “oncofertility” consultations have developed extensively in recent years and should now be an integral part of the care pathway for all young female patients with cancer. Several “fertility preservation” techniques designed to cryopreserve gametes, or preserve reproductive capacity, are now available, and others are currently in development. In France, since 1994, these methods have been included in various pieces of bioethics legislation. Article L.2141 11, modified by law 2011-814 of July 7, 2011, states that “All persons whose fertility is likely to be impaired by their medical care, or whose fertility risks being prematurely impaired, may have their gametes or reproductive tissue collected and preserved with a view to their later use of assisted reproductive technology, or with a view to preserving and restoring their fertility.” Fertility preservation methods are also included in the 2014-2019 Cancer Plan, which stipulates that “all patients must have access to cancer treatments, and innovative treatments in particular.”
Improving gamete preservation
Several techniques for cryopreserving female gametes are currently available. The standard method involves freezing mature eggs or embryos obtained from these eggs. It is not however suitable for prepubescent girls, who need to begin treatment urgently, and can also present problems in patients with hormone-sensitive cancers. Therefore, other techniques, although still considered experimental, may be offered in these situations.
Improving the available methods and developing new strategies is currently a major focus for oncofertility. This is one of the areas of research on which the Inserm team led by Nadine Binard and Charlotte Sonigo is working, in collaboration with Prof. Michael Grynberg.
Using anti-Müllerian hormone
Chemotherapy reduces fertility through a direct toxic effect on the ovaries. Cyclophosphamide, which is commonly used in cancer treatment, causes massive destruction of the germ cells contained in the ovarian follicles. In a mouse model, researchers have recently shown that treatment with anti-Müllerian hormone, which is normally secreted by the ovaries, can limit reduction of follicular reserve during chemotherapy. Use of anti-Müllerian hormone is therefore a promising approach to fertility preservation.
1.3. The role of new technologies: Using artificial intelligence in reproductive research
The store of germ cells contained in the follicles constitutes the ovarian reserve. Assessing the quantity of these germ cells is a common way of providing information on ovarian physiology and of measuring the impact of the environment on the ovaries. The standard method used in mice is time-consuming and tedious. In conjunction with a company specializing in artificial intelligence, Inserm researchers have recently developed an automated artificial intelligence method for follicle counting that uses a deep learning approach.[2] This new tool will be made available to the fertility research scientific community, saving a great deal of time and enabling better reproducibility of data.
Research into combating endometriosis
Endometriosis is a complex disorder characterized by chronic inflammation due to the presence of tissue resembling the uterine lining outside the uterus. This “ectopic uterus” continues to respond to ovarian hormones, which in some women can cause severe pain and sometimes infertility. In response to increased visibility of the disease in the media, notably due to the work of patient organizations, the French health minister has announced an action plan to improve management of endometriosis. In terms of research, there has been a surge in studies of endometriosis over the last 5 years. Around 1,200 articles per year are being produced by researchers around the world, helping to advance understanding of this disorder.
An estimated 1 in 10 women have some form of endometriosis.
The locations of endometriosis lesions vary.
Endometrial cell reflux during periods occurs in 90% of women, but only 10% of them develop disease.
The disease is typically described as having 4 stages, based on the extent and depth of lesions; however, there is no correlation between disease symptoms and severity.
There are 3 forms of endometriosis: superficial peritoneal endometriosis, ovarian endometriosis (or endometrial cyst, or endometrioma), and deep endometriosis.
2.1. Improving understanding of the causes
The epidemiological approach
At present, little is known about the causes of endometriosis, its natural history, and the factors affecting its progression. Epidemiological research plays a crucial role in advancing knowledge in this area. There are only a few large epidemiological cohorts around the world in which these aspects can be explored. The largest cohort for exploring endometriosis risk factors is currently a cohort of 116,430 American female nurses who were between 25 and 42 years old in 1989. The risk factors identified in the literature and confirmed in this cohort include: low birth weight, early menstruation, low body mass index, and short menstrual cycles (under 24 days).[3] However, beyond these factors, little information is available on the causes of the disease, and its natural history is largely unknown. The following table is based on a review of the literature published in August 2018:
*The positive association between smoking and reduced risk of endometriosis may be explained by the antiestrogenic effect of tobacco. This would confirm the therapeutic interest of estrogen blockers, which are available in drug form: far more suitable than cigarettes, whose harmful effects have been widely documented.
In a bid to improve understanding of this disease, several epidemiological studies are being launched in France by the team led by Marina Kvaskoff, Inserm epidemiologist and researcher. These include a recently formed patient cohort dedicated to the study of endometriosis: the ComPaRe-Endometriosis cohort. The study team’s objective is to have enough women in the cohort to obtain robust findings in relation to the many questions that are still unanswered about this disease. In less than 6 months, over 8,000 women have already taken part in the study. The team aims to recruit 15,000 to 20,000 participants, and a broad call for participation has gone out to women with endometriosis or adenomyosis (a form of endometriosis limited to the muscle wall of the uterus) to help speed up research into these disorders simply by completing online questionnaires about their experience of the disease (https://compare.aphp.fr/). The study initially looks to explore the natural history of the disease (change in the symptoms and characteristics of the disease over time), and to identify the factors that determine its progression and result in better response to treatment. This research will also make it possible to describe the circumstances of diagnosis and the patient care pathway, and to assess the impact of the disease on patients’ daily lives.
Endometriosis is also being studied within large French cohorts, such as the CONSTANCES cohort, a prospective study of 200,000 men and women (105,000 women) representative of the French population. Marina Kvaskoff’s team has developed an epidemiological research study to determine the prevalence and incidence of the disease in France, and to explore its risk factors within this cohort. Other studies are currently in development and will be conducted in other cohorts in due course.
The environmental approach
Several epidemiological studies have explored the associations between organochlorine chemicals (solvents, pesticides, insecticides, fungicides, etc.) and endometriosis, but their results have been inconsistent. A French meta-analysis of 17 studies[4] published in February 2019 attempted to draw more robust findings. The risk of developing endometriosis was 1.65 times higher in women exposed to dioxins, 1.70 times higher for those exposed to polychlorinated biphenyls (PCB), and 1.23 times higher for organochlorine pesticides. Although statistically significant, these estimates should be considered with caution due to the significant heterogeneity of the studies and the small estimated effect size. The level of evidence was judged to be “moderate” with a serious risk of bias, supporting the need to conduct further well-designed epidemiological research in order to fill the persistent data gaps.
Using the genetic and epigenetic approach for early detection
Detecting endometriosis in the early stages, before patients experience symptoms, would make it possible to improve patient care. Although the heritability of endometriosis has been estimated at 50%, it is highly complex and clearly highly polygenic. Numerous candidate genes have been studied from this perspective in analyses of disease predisposition. Initial results have shown that there is no gene for endometriosis, but that the existence of genetic variants characteristic of the disease could enable it to be diagnosed and to improve patient care. In 2017, efforts by the international community made it possible to identify a total of 14 variants (located on the genes WNT4, GREB1, ETAA1, IL1A, KDR, ID4, CDKN2B-AS1, VEZT, FN1, CCDC170, SYNE1, FSHB, and in the chromosomal regions 7p15.2 and 7p12.3). These 14 genes are involved in proliferation and the cell cycle, adhesion and the extracellular matrix, andinflammation, which makes sense in relation to endometriosis. However, each of the variants identified explain only a small part of the genetic variation in endometriosis. In future, the combination of high-risk alleles in a patient might provide a probability of being affected that could be used to diagnose patients and categorize them based on endometriosis type and severity.
The existence of specific epigenetic markers for endometriosis could also theoretically be used for early detection, with endometrial cells presenting specific epigenetic abnormalities that modify expression of the main transcription factors. However, it is not known how the interactions between the defective epigenomic cells and mutated epithelial cell genes contribute to the pathogenesis of endometriosis.
The microRNA approach
The full complexity of endometriosis cannot however be understood through genetics alone. Genes only influence phenotype through their expression. This expression is regulated by epigenetic molecular mechanisms. As such, most research focuses on studying the microRNA that could be “markers” for the disease. Several have been identified in patients’ plasma thus far, but with very poor reproducibility from one research team to the next. For example, a study published in 2013[5] identified just four miRNA (miR-199a, miR122, miR145*, and miR-542-3p) as enough to categorize patients, with very few errors. Confirmation of this article’s findings in independent cohorts has however been slow. One possible explanation for this is the fact that extraction of circulating RNA remains very heterogeneous from one study to the next, perhaps due to the technical tools used in extraction. In future, new, more comprehensive approaches could provide more consistent results.
The cellular approach: oxidative stress
Several studies have shown increased oxidative stress in the serum of women with endometriosis. Oxidative stress is a highly general mechanism that induces and is caused by inflammation. It would seem logical to find changes linked to oxidative stress in the context of a painful disease like endometriosis. In mouse models, treatment with antioxidants (N-acetylcysteine) has been seen to reduce endometrial lesions.
Research led by a team from the Institut Cochin has also identified several genes linked to glutathione metabolism within the gene cascades that are deregulated in endometriosis lesions. Glutathione is a peptide that plays a key role in detoxification of hydrogen peroxide, a central molecule in oxidative stress. Down-regulation, particularly of the GCLM and GCLC genes crucial to glutathione synthesis, could explain increased oxidative stress in endometriosis lesions.
The dysfunctional immune system: a possible approach?
The survival of endometrial cells outside the uterus could be linked to poor function of the immune system causing chronic local inflammation. Studies have shown an increase in some immune cells around endometriosis lesions.
2.2. Treatment: areas of research and latest findings
Changing diagnostic methods: phasing out surgery
Before considering treatment, the first stage is to reduce the diagnosis time for endometriosis, which is currently around 7 to 10 years after onset of the initial symptoms. With this in mind, doctors and researchers are working to develop a diagnostic score, based on a dozen questions, from which doctors will be able to provide a diagnosis with 85-90% reliability. This score may be accompanied if necessary by imaging, which can inform endometriosis diagnosis if carried out and interpreted by trained medical personnel.
Doctors and researchers agree that diagnostic surgery is contraindicated for endometriosis.
The 3 pillars of treatment
Drug therapy, surgery, and assisted reproductive technology (ART) are currently the only 3 methods for treating the symptoms of endometriosis and its potential impact on fertility. In the absence of new treatments, the key is to understand the role played by each component in this therapeutic arsenal, so that they can be used effectively.
Drug therapy is based on blocking ovarian function to bring about artificial menopause via continuous administration of contraceptives. These therapies (the combined pill, estrogen pill, or GnRH agonists) must be personalized and adapted to the needs of the patient. These therapies should be prescribed as the first-line treatment for women who are not seeking to become pregnant, in order to reduce the pain caused by the disease.
For patients who want to conceive, ART and surgery may be considered. ART should be used routinely before all surgical procedures in order to maximize the chance of conceiving a child for couples who want to do so. Surgery must not be used in women who do not want to conceive in whom drug therapy is effective. Endometriosis surgery can be highly invasive and debilitating (removing some parts of the colon, with a high risk of ovarian reserve depletion if ovarian cysts are removed, etc.), and does not prevent the disease from recurring, as it does not treat the cause. Doctors and researchers also agree that women who undergo surgery at a young age have a high risk of their endometriosis lesions recurring, and encounter further difficulties if they decide they want to become pregnant.
All efforts must therefore be made to move away from using surgery as the standard treatment for endometriosis, as has too often been the case in the past.
Some forms of endometriosis – particularly those affecting the ovaries – are now an indication for providing women with access to various fertility preservation techniques.
The role of new technologies: the example of high-intensity focused ultrasound
In Lyon, teams of research clinicians led by Prof. Gil Dubernard (Hospices Civils de Lyon and Inserm unit 1032 LabTAU) have developed an ultrasound-based treatment for bowel endometriosis. When endometriosis infiltrates the rectal wall, it causes debilitating rectal pain that may affect quality of life. After failure of medical treatment, a surgical procedure is often proposed that consists of removing all or part of the rectum and sometimes requires a temporary colostomy (artificial anus).
A phase I clinical trial carried out in 11 patients in 2017 demonstrated that high-intensity focused ultrasound may be a useful alternative to surgery. An ultrasound probe inserted into the rectal passage is able to “desensitize” the lesions within a few minutes. A follow-up trial of 12 patients seeking to confirm these initial results was completed on April 1, 2019. Data analysis is ongoing and will be available shortly.
Meanwhile, in collaboration with the company EDAP TMS (the clinical trial sponsor), the therapeutic ultrasound Inserm laboratory led by Cyril Lafon, LabTAU (Université Claude Bernard Lyon 1/Inserm), is working on optimizing the conditions of ultrasound delivery (insonification) and improving the ergonomics of the probe in order to increase the number of patients eligible for this new treatment.
It is highly likely that this innovative therapy will replace many of the rectal surgeries carried out in this functional disorder that resolves upon menopause.
Millar RP, Sonigo C, Anderson RA, George J, Maione L, Brailly-Tabard S, Chanson P, Binart N, Young J.
[2]Sonigo C, Jankowski S, Yoo O, Trassard O, Bousquet N, Grynberg M, Beau I, Binart N. High-throughput ovarian follicle counting by an innovative deep learning approach. Sci Rep. 2018 Sep 10;8(1):13499. doi: 10.1038/s41598-018-31883-8.
Researchers are now able to edit the genome with precision using the “gene editing scissors” of CRISPR-Cas9, which is a highly promising tool for gene therapy.The technical challenge now is to get this tool into the genome of certain cells.With this in mind, a joint team from Inserm, the CNRS, the Université Claude Bernard Lyon 1, and the École Normale Supérieure de Lyon, working within the International Center for Infectiology Research (CIRI), have developed capsules that allow CRISPR-Cas9 to reach the target DNA: Nanoblades.Described in a recent article in Nature Communications, they open up avenues of research for genome editing in human stem cells.
Since 2012, the scientific community has had access to a revolutionary method for highly precise genome “surgery”: the CRISPR-Cas9 system. These molecular scissors are able to cut DNA at a precise place in a wide variety of cell types. The technique therefore offers significant prospects for research and human health. However, getting these “gene editing scissors” to their target—including the genome of certain stem cells—remains technically challenging.
Tackling this problem has been the focus for research teams from Inserm, the CNRS, the Université Claude Bernard Lyon 1, and the École Normale Supérieure de Lyon, who have developed Nanoblades,[1] particles that enable CRISPR-Cas9 to be delivered into numerous different cells, including human cells.
The scientists had the idea of encapsulating the CRISPR-Cas9 system in structures that strongly resemble viruses as a way to deliver it into target cells, by fusing with the target cell membrane.
In developing Nanoblades, researchers exploited the properties of the retroviral Gag protein, which is able to produce viral particles that have no genome and are therefore non-infectious. The research team fused the Gag protein from a mouse retrovirus with the Cas9 protein—the scissor component of the CRISPR system. This new “fusion” protein is what makes Nanoblades original.
As a result, and unlike classic genome modification techniques, Nanoblades encapsulate a CRISPR/Cas9 complex that is immediately functional rather than delivering a nucleic acid coding for the CRISPR-Cas9 system in the treated cells. “The action of CRISPR-Cas9 on the cells is therefore temporary.It is also more precise and preserves the non-target regions of the genome, which is a particularly important feature in the context of therapeutic applications”, explain the authors.
Legend:
Représentation schématique d’une particule Nanoblades livrant CRISPR CAS9
Schematic diagram of a Nanoblades particle delivering CRISPR-Cas9
La protéine GAG tapissant l’intérieur des particules rétrovirales
The Gag protein internally lining the retroviral particles
La protéine CAS9, ciseau effecteur du système CRISPR, pouvant cliver l’ADN
The Cas9 protein, the scissor component of the CRISPR system, is able to cleave DNA
L’ARN guide, qui va placer CAS9 sur la région ADN cible. Il a une affinité naturelle pour CAS9
The RNA guides Cas9, then positions it at the target DNA region. It has a natural affinity for Cas9
Les deux enveloppes virales conférant un tropisme large aux particules
The two viral envelopes give the particles a broad tropism
La bicouche lipidique qui entoure la particule
The lipid bilayer surrounding the particle
Finally, researchers used an original combination of two viral envelope proteins on the surface of Nanoblades to enable them to enter a wide range of target cells.
The scientists have demonstrated the efficacy of Nanoblades in vivo, in mouse embryos, for a broad range of applications and in a broad panel of target cells for which other methods have had limited success. “Nanoblades have turned out to be particularly effective for editing the genome of human stem cells. These cells are of major therapeutic interest (particularly in tissue regeneration), but remain difficult to manipulate using standard methods”, explain the study authors.
[1] Nanoblades have been tested in mice and were patented by Inserm Transfert in 2016.
Marking of the different mast cell populations (in green and red), which are major players in allergic responses, on contact with neurons (white) in mouse skin. © Dr. Marie Tauber and Dr. Lilian Basso.
