In Primates, the Appendix Is Found to Have a Protective Effect Against Infectious Diarrhea

singe géladaThe gelada (Theropithecus gelada) is one of the primate species without an appendix referenced in this research. ©Vallée des singes

Although the cecal appendix is no longer considered a vestige of evolution with no particular role, its exact function remains to be discovered and several hypotheses are currently being explored. A research team from Inserm, CNRS, the French National Museum of Natural History (MNHN), Université de Rennes, Sorbonne Université and the Eugène Marquis Center looked at how the presence of an appendix affects the onset and severity of infectious diarrhea in primates, an animal order that is particularly affected by these diseases. Its research shows that the primate species with an appendix are less affected by infectious diarrhea and that it is less severe than in those without an appendix. They are also better protected against these infections during the first part of their lives, a period that is more vulnerable to severe diarrhea and crucial for reproduction. These findings, published in Scientific Reports provide new evidence supporting the advantageous role of the appendix in evolution.

The cecal appendix (more commonly referred to as the “appendix”) is a small blind-ended tube located in the lower part of the cecum, the first part of the large intestine. It is found in some mammals and particularly in some primate species, including humans. While it has long been considered an unnecessary vestige of evolution, research over the past decade has challenged this paradigm with scientists now tending to view it as a potential evolutionary advantage, although its function remains poorly understood.

One hypothesis concerning the role of the appendix is based on its composition of microorganisms. Different from that of the rest of the gut microbiota, it could constitute a reservoir of healthy flora safeguarded from the fecal flow, likely to recolonize the gut after a gut infection and enable faster remission. And it just so happens that primates are an animal order particularly affected by infectious diarrhea. In humans, mortality related to these infections was identified in 2015 as being the second leading cause of mortality in children between 1 month and 5 years of age. More specifically, in patients who have had their appendix removed (appendectomy), there has been an increased risk of the occurrence and/or severity of certain forms of infectious diarrhea, although no direct link has been demonstrated at this time.

A research team led by Éric Ogier-Denis, Inserm research director at the Oncogenesis Stress Signaling unit Inserm/Université de Rennes/Eugène Marquis Center), and Michel Laurin, CNRS research director at the Center for Research on Paleontology – Paris (CNRS/MNHN/Sorbonne Université), had shown in previous research that the mammalian species with an appendix had longer longevity than those without one[1]. As a continuation of this research, the team looked at how the presence of a cecal appendix could affect the frequency and severity of diarrhea in primates and thus be a determining factor in the life span of each species.

To do this, the researchers examined the veterinary records of 1 251 primates of 45 different species – 13 with an appendix, 32 without – living in semi-liberty in “La Vallée des Singes” zoological park in Romagne, France. They listed the frequency and severity of the diarrhea episodes that occurred between 1998 and 2018 in these animals.

gorille (Gorilla gorilla gorilla)The gorilla (Gorilla gorilla gorilla) is one of the species of primates with an appendix referenced in this research. ©Vallée des singes

Half of the primates had experienced at least one episode of diarrhea during the 20-year follow-up period, with 13% of the episodes qualifying as “severe”.

In the primates with an appendix, the frequency of diarrhea episodes was very much lower (by around 85%) than in those without one. The cases of severe diarrhea were also much less frequent, particularly during the first quarter of life when the risk is highest (but then gradually decreases throughout life).

In addition, in the species with an appendix, the median age of onset of diarrhea, whether severe or not, was significantly higher.

These findings support the hypothesis of a protective role of the cecal appendix against infectious diarrhea in primates, comments Jérémie Bardin, co-first author of the study. The observation of a particularly high protective effect in the first part of life, the period most vulnerable to severe diarrhea, but also the most optimal in terms of reproductive capacity, argues in favor of a selective advantage role in evolution”, adds Ogier-Denis.

The research should therefore be continued in order to gain deeper insights into the cecal appendix and a better understanding of the role of its specific flora. One of the next steps could be to compare the composition of the appendix microbiota between primate species in order to highlight possible similarities.

Finally, the last interesting observation in this study was that none of the primates with an appendix had been diagnosed with acute appendicitis over the 20-year period.

Although this is more common in humans than in other primate species, if the protection associated with the presence of the appendix in humans is of the same level as that observed in primates, it would very much counterbalance the risk related to fatal appendicitis“, concludes Maxime Collard, co-first author of the study.

[1]See our August 3, 2021 press release:

Neurodevelopmental Disorders in Children: A New Gene Called Into Question

ADN© Double helix DNA – National Human Genome Research Institute, National Institutes of Health.

In the face of childhood neurodevelopmental disorders, how can we get out of the therapeutic “dead end”? The answer could well be found in the genes of the proteasome – an intracellular mechanism that is responsible for removing defective proteins from the cell. A research team from Inserm, CNRS, Nantes Université and Nantes University Hospital, at the Thorax Institute and in collaboration with international teams, studied the genome of 23 children with neurodevelopmental disorders. What they found were fifteen mutations in the PSMC3 gene of the proteasome, which may be involved in their disease. This research, published in Science Translational Medicine, opens up new research perspectives in order to better understand these diseases and identify treatments.

The origin of neurodevelopmental disorders in children remains difficult to identify, with patients and their families often having to wait several years for a diagnosis.

A research team from the Thorax Institute (Inserm/CNRS/Nantes Université/Nantes University Hospital), led by Stéphane Bézieau, Head of the Medical Genetics Department at Nantes University Hospital, has been working on the genetics of neurodevelopmental disorders in children for several years. In particular, its research has led to the identification of the role of a gene called PSMD12 in a childhood neurodevelopmental disease. This gene is expressed in a large complex of proteins located in the cells, which is called the proteasome.

The proteasome acts as a kind of “garbage collector” within the cell. By eliminating the defective proteins it contains, the proteasome plays a decisive role in a large number of cell processes. Alterations that may appear on some of its constituent genes are likely to affect its ability to break down defective proteins. Their accumulation results in the development of a wide variety of pathologies.

In new research[1] in collaboration with international teams, the team continued to explore the links between proteasome gene mutations and neurodevelopmental diseases. This time it was more specifically interested in the proteasome PSMC3 gene and its involvement in the neurodevelopmental disorders of 23 young European, U.S. and Australian patients with neurological symptoms (delayed speech, intellectual disability, or behavioral problems) frequently associated with abnormalities of the face and malformations of the skeleton, heart and other organs.

Thanks to the full sequencing of the genome of these patients, the researchers have revealed fifteen mutations in the PSMC3 gene likely to explain the origin of the symptoms.

“It quickly became apparent that the cells of patients with a defective PSMC3 gene were literally overloaded with unnecessary and toxic proteins,” explains Frédéric Ebstein, Inserm researcher and first author of the study.

He compares this phenomenon to that observed in some age-related neurodegenerative diseases, such as Alzheimer’s or Parkinson’s.

“The discovery of the involvement of a second gene in childhood neurodevelopmental disorders provides unprecedented insight into this group of rare diseases that had been unknown until recently, clarifies researcher Sébastien Küry, an engineer at Nantes University Hospital, who co-signed this research. This research, combined with the team’s recent discovery of other genes involved [but not published as yet, ed.], opens up major perspectives in the understanding of this group of neurodevelopmental diseases as well as prospects for their treatment,” he concludes.


[1]This research is supported by the French National Research Agency (ANR), the European Union (European Joint Programme on Rare Diseases), and the insurance company AXA.

A Major Advance in the Genetics and Risk Factors of a Form of Infarction That Mainly Affects Women

SCAD is a form of infarction that mainly affects women. © Fotalia


Spontaneous coronary artery dissection, more commonly known under the acronym SCAD, is a cause of infarction of which 9 out of 10 of its victims are women in their forties in apparent good health. Still poorly understood, it is often underdiagnosed, which complicates treatment despite the fact that it could represent up to one third of infarction cases in women under 60 years of age. In order to understand its genetic causes and biological mechanisms, a new international study led by Inserm Research Director Nabila Bouatia-Naji at the Paris-Cardiovascular Research Center – PARCC (Inserm/Université Paris Cité) was set up. Its findings show the genetic causes that define the risk of SCAD to be very numerous and distributed across the entire patient genome. The study has identified 16 genomic regions associated with a higher risk of SCAD, paving the way for a better understanding of the biological mechanisms that underlie this disease. The study was published on May 29, 2023 in Nature Genetics.

Unlike the majority of cardiovascular diseases, such as myocardial infarction, which mainly affect older and/or overweight men, spontaneous coronary artery dissection (SCAD) is a form of infarction that affects women in 9 out of 10 cases. Although these women are often in their forties, the disease can occur earlier – in the year after giving birth, or later – during the transition to menopause. Despite being increasingly recognized as a major form of infarction within this population, SCAD remains quite poorly documented due to a lack of data and a lack of knowledge of its specific risk factors – particularly genetic.

Over the past 20 years, considerable progress has been made in detailing the mechanisms of development of coronary diseases such as atherosclerosis and the very rare and syndromic forms of cardiovascular diseases. Such knowledge is essential in order to better understand these diseases and devise improved and personalized strategies for their prevention and treatment.

Nevertheless, research has lagged far behind in the understanding of diseases such as SCAD that affect women at key stages of their lives. It is therefore essential to now focus on this understudied cardiovascular disease and its own specific genetic risk.

The team of Inserm geneticist Nabila Bouatia-Najia conducted a large-scale study on the subject, coordinating a meta-analysis of 8 genome-wide association studies (GWAS)[1].  By comparing the genetic data of over 1900 patients with around 9300 healthy individuals, the scientists identified 16 genomic regions (or loci) of genetic predisposition to SCAD.


Towards a Better Understanding of the Biological Mechanisms

This study began by showing that the genetic variations most commonly found in patients having survived SCAD play a role in the composition of the “cement” that surrounds the coronary artery cells.

However, one of the genes identified is F3 and it encodes the tissue coagulation factor. Normally, the tissue factor initiates coagulation at cell level in order to resorb any hematomas. The results of the study suggest that a lack of F3 expression is often found in patients, constituting a potential cause of poor artery repair, which can lead to tearing. Poor hematoma resorption would therefore be a hitherto unknown genetic cause.

One of the other objectives of this study was to position SCAD in relation to other cardiovascular diseases in order to better understand its epidemiological particularities. Using the data that determine genetic cardiovascular risk factors and clever statistical methods, the scientists revealed a robust link between high blood pressure and risk of SCAD, while confirming that high cholesterol, overweight, and type 2 diabetes had no impact on this risk.

“This finding could therefore be clinically interesting in the longer term, to encourage doctors to closely monitor blood pressure changes in patients at increased genetic risk of SCAD,” explains Bouatia-Naji, Inserm Research Director and last author of the study.

Finally, this study reveals a genetic link between SCAD-related infarction and atherosclerosis-related infarction. Indeed, the researchers have shown that a large number of genomic regions predisposing to SCAD are shared with those of atherosclerosis-related infarction. However, even if these were the same genetic variants, the alleles[2] that are more common in SCAD patients are routinely described as being less common in subjects with atherosclerosis-related infarction.

“This finding is very surprising because they show that, depending on whether you are faced with a young woman with no risk factors, or an older man with risk factors, the genetic causes and biological mechanisms associated with their infarction can be opposed.  Our findings highlight the need to better understand the particularities of cardiovascular diseases in young women in order to improve their follow-up, which is currently identical to that of atherosclerosis-related infarction,” concludes Bouatia-Naji.

Building on these findings, the team is now working to develop new cell and animal models that better account for the genetic factors involved in the disease, particularly in order to better study their impact on the condition of the arteries. Always with a longer-term objective in mind: to shed the spotlight on a cardiovascular disease that is essentially female and all too often neglected, and to improve how it is understood and treated.


[1] Genome-wide association study, widely performed for several years now, which consists of analyzing the entire genome of thousands of healthy and sick individuals in order to identify the genomic regions which contain the genes influencing the vulnerability of people to the condition in question

[2] An allele is a version of a genetic variant resulting from a change in the DNA sequence. Any DNA sequence can have several alleles, which often determine the appearance of different hereditary characteristics.

A New Target to Regress Liver Fibrosis


Cirrhosis is the final stage of fibrosis associated with chronic liver diseases. It affects 200,000 to 500,000 individuals in France and is responsible for 170,000 deaths per year in Europe. © Adobe Stock

Chronic liver diseases are characterized by persistent inflammation that contributes to their progression to more severe stages. They may progress to fibrosis and cirrhosis, and then require liver transplantation. Therefore, limiting the progression of fibrosis and bringing about its regression is a major therapeutic challenge. Several studies have recently suggested that one interesting approach could be to target the inflammatory response. In new research, scientists from Inserm and Université Paris-Cité at the Inflammation Research Center (CRI), in collaboration with teams from the Paris Public Hospitals Group (AP-HP)[1], have shown that blocking the activation of a particular population of T cells, the Mucosal-Associated Invariant T (MAIT) cells, could halt the progression of fibrosis and even bring about its regression. Targeting the MAIT cells involved in the inflammation seen in fibrosis and cirrhosis would therefore open up new avenues for better therapeutic care. This study has been published in Nature Communications.

Mainly alcoholic, viral, or metabolic in origin, cirrhosis is the last stage of fibrosis associated with chronic liver diseases. Cirrhosis affects between 200 000 and 500 000 people in France and is responsible for 170 000 deaths per year in Europe. Ultimately, it leads to liver failure for which the only cure is transplantation.

One characteristic of chronic liver diseases is persistent inflammation that contributes to their progression to more severe stages, particularly fibrosis and its final stage, cirrhosis. A better understanding of how to regulate this inflammatory response therefore constitutes a major challenge in developing new strategies to treat these diseases.

In 2018, the team of Inserm researcher Sophie Lotersztajn had shown that a population of T cells called MAIT promoted the progression of liver fibrosis. These immune cells are particularly abundant in the human liver and are involved in the inflammatory processes associated with fibrosis.

In their new study, the scientist and her colleagues worked on the basis of liver samples from cirrhotic patients as well as from mouse models of the disease.

They showed that the administration of a pharmacological agent to inhibit the activation of MAIT cells can limit liver inflammation and not only halt the progression of fibrosis, but also regress it.

It is now well known that other immune cells, such as the macrophages, play a central role in the progression and regression of fibrosis. Here, analysis of the mechanisms involved showed that blocking the activation of MAIT cells interrupts their dialog with profibrogenic macrophages, i.e. accelerators of fibrosis, and promotes the emergence of fibrosis-resolutive macrophages.

cellules MAIT

In the first image, the MAIT cells (in red, shown using arrows) are located near fibrogenic cells (in green) in the liver of cirrhotic patients. In the second image, the MAIT cells (in red) are activated (activation marker in green) in the liver of cirrhotic patients. This activation is blocked in the presence of a MAIT cell inhibitor. Credits: Sophie Lotersztajn


“Cirrhosis is a major public health problem. Even though the only treatment is liver transplantation, our research opens up other therapeutic avenues for targeting inflammation and halting or even regressing fibrosis. The research now needs to be continued, particularly in order to develop drug candidates that target and inhibit the MAIT cells,” concludes Lotersztajn.


[1] This research is the result of a collaboration between the team of Drs. Sophie Lotersztajn and Hélène Gilgenkrantz (Inflammation Research Center (CRI) Inserm-Université Paris Cité), the team of Dr. Valérie Paradis at the CRI (also Department of Pathology, Beaujon Hospital), Department of Anesthesiology and Critical Care (Prof. Emmanuel Weiss), the teams of Institut Curie (Dr. Olivier Lantz), Institut St Louis (Dr. Michèle Goodhardt) and Génosplice (Dr. Pierre de la Grange)

Research shows fatty liver disease endangers brain health

Liver cells invaded by lipid droplets (in white) from an animal on a diet rich in sugars and fats. © University Institute of Pathology of the University of Lausanne.

People with liver disease caused by eating too much sugar and fat could be at increased risk of developing serious neurological conditions like depression or dementia. In a study examining the link between non-alcoholic fatty liver disease (NAFLD) and brain dysfunction, scientists at the Roger Williams Institute of Hepatology, affiliated to King’s College London and the University of Lausanne, found an accumulation of fat in the liver causes a decrease in oxygen to the brain and inflammation to brain tissue – both of which have been proven to lead to the onset of severe brain diseases.

NAFLD affects approximately 25% of the population and more than 80% of morbidly obese people. Several studies have reported the negative effects of an unhealthy diet and obesity can have on brain function however this is believed to be the first study that clearly links NAFLD with brain deterioration and identifies a potential therapeutic target.

The research, conducted in collaboration with Inserm (the French National Institute of Health and Medical Research) and the University of Poitiers in France , involved feeding two different diets to mice. Half of the mice consumed a diet with no more than 10% fat in their calorie intake, while the other half’s calorie intake contained 55% fat; intended to resemble a diet of processed foods and sugary drinks.

After 16 weeks researchers conducted a series of tests to compare the effects of these diets on the body and more specifically, on the liver and the brain.

They found that all mice consuming the higher levels of fat were considered obese, and developed NAFLD, insulin resistance and brain dysfunction.

The study which was funded by the University of Lausanne and Foundation for Liver Research, published today in The Journal of Hepatology, also showed that the brain of mice with NAFLD suffered from lower oxygen levels. This is because the disease affects the number and thickness of the brain blood vessels, which deliver less oxygen to the tissue, but also due to specific cells consuming more oxygen while the brain is becoming inflamed. These mice were also more anxious and showed signs of depression.

By comparison, the mice consuming the healthy diet did not develop NAFLD or insulin resistance, they behaved normally, and their brain was completely healthy.

It is very concerning to see the effect that fat accumulation in the liver can have on the brain, especially because it often starts off mild and can exist silently for many years without people knowing they have it,” said lead author Dr Anna Hadjihambi, sub-team lead in the Liver-Brain Axis group at the Roger Williams Institute of Hepatology and honorary lecturer at King’s College London.

To try and combat the dangerous effect that NAFLD has on the brain, the scientists bred mice with lower levels of a whole-body protein known as Monocarboxylate Transporter 1 (MCT1) – a protein specialised in the transport of energy substrates used by various cells for their normal function.

When these mice were fed the same unhealthy fat- and sugar-rich diet as those in the initial experiment, they had no fat accumulation in the liver and exhibited no sign of brain dysfunction – they were protected from both ailments.

Identifying MCT1 as a key element in the development of both NAFLD and its associated brain dysfunction opens interesting perspectives,” said Professor Luc Pellerin, director of the Inserm U1313 research unit at the University of Poitiers in France and senior researcher in the study. “It highlights potential mechanisms at play within the liver-brain axis and points to a possible therapeutic target.

Dr Hadjihambi added: “This research emphasises that cutting down the amount of sugar and fat in our diets is not only important for tackling obesity, but also for protecting the liver to maintain brain health and minimise the risk of developing conditions like depression and dementia during ageing, when our brain becomes even more fragile.

The full paper is available to view online in The Journal of Hepatology.

Decoding a direct dialog between the gut microbiota and the brain

Diagram showing the direct dialog between the gut microbiota and the brain

© Institut Pasteur / Pascal Marseaud


Gut microbiota by-products circulate in the bloodstream, regulating host physiological processes including immunity, metabolism and brain functions. Scientists from the Institut Pasteur (a partner research organization of Université Paris Cité), Inserm and the CNRS have discovered that hypothalamic neurons in an animal model directly detect variations in bacterial activity and adapt appetite and body temperature accordingly. These findings demonstrate that a direct dialog occurs between the gut microbiota and the brain, a discovery that could lead to new therapeutic approaches for tackling metabolic disorders such as diabetes and obesity. The findings are due to be published in Science on 2022 04 15.

The gut is the body’s largest reservoir of bacteria. A growing body of evidence reveals the degree of interdependence between hosts and their gut microbiota, and emphasizes the importance of the gut-brain axis.

At the Institut Pasteur, neurobiologists from the Perception and Memory Unit (Institut Pasteur/CNRS)[1], immunobiologists from the Microenvironment and Immunity Unit (Institut Pasteur/Inserm), and microbiologists from the Biology and Genetics of the Bacterial Cell Wall Unit (Institut Pasteur/CNRS/Inserm)[2] have shared their expertise to investigate how bacteria in the gut directly control the activity of particular neurons in the brain.

The scientists focused on the NOD2 (nucleotide oligomerization domain) receptor which is found inside of mostly immune cells. This receptor detects the presence of muropeptides, which are the building blocks of the bacterial cell wall. Moreover, it has previously been established that variants of the gene coding for the NOD2 receptor are associated with digestive disorders, including Crohn’s disease, as well as neurological diseases and mood disorders. However, these data were insufficient to demonstrate a direct relationship between neuronal activity in the brain and bacterial activity in the gut. This was revealed by the consortium of scientists in the new study.

Using brain imaging techniques, the scientists initially observed that the NOD2 receptor in mice is expressed by neurons in different regions of the brain, and in particular, in a region known as the hypothalamus. They subsequently discovered that these neurons’ electrical activity is suppressed when they come into contact with bacterial muropeptides from the gut. “Muropeptides in the gut, blood and brain are considered to be markers of bacterial proliferation,” explains Ivo G. Boneca, Head of the Biology and Genetics of the Bacterial Cell Wall Unit at the Institut Pasteur (CNRS/Inserm). Conversely, if the NOD2 receptor is absent, these neurons are no longer suppressed by muropeptides. Consequently, the brain loses control of food intake and body temperature. The mice gain weight and are more susceptible to developing type 2 diabetes, particularly in older females.

In this study, the scientists have demonstrated the astonishing fact that neurons perceive bacterial muropeptides directly, while this task was thought to be primarily assigned to immune cells. “It is extraordinary to discover that bacterial fragments act directly on a brain center as strategic as the hypothalamus, which is known to manage vital functions such as body temperature, reproduction, hunger and thirst,” comments Pierre-Marie Lledo, CNRS scientist and Head of the Institut Pasteur’s Perception and Memory Unit.

The neurons thus appear to detect bacterial activity (proliferation and death) as a direct gauge of the impact of food intake on the intestinal ecosystem. “Excessive intake of a specific food may stimulate the disproportionate growth of certain bacteria or pathogens, thus jeopardizing intestinal balance,” says Gérard Eberl, Head of the Microenvironment and Immunity Unit at the Institut Pasteur (Inserm).

The impact of muropeptides on hypothalamic neurons and metabolism raises questions on their potential role in other brain functions, and may help us understand the link between certain brain diseases and genetic variants of NOD2. This discovery paves the way for new interdisciplinary projects at the frontier between neurosciences, immunology and microbiology, and ultimately, for new therapeutic approaches to brain diseases and metabolic disorders such as diabetes and obesity.


[1] This research unit is also known as the “Genes, Synapses and Cognition Laboratory” (Institut Pasteur/CNRS).
Paris Brain Institute (CNRS/Inserm/Sorbonne Université/AP-HP) also contributed to these findings.

[2] The CNRS unit’s name is the “Integrative and Molecular Microbiology Unit” and the Inserm unit’s name is the “Host-Microbe Interactions and Pathophysiology Unit” (Institut Pasteur/CNRS/Inserm).

Artificial Sweeteners: Possible Link to Increased Cancer Risk

édulcorant artificiel

Aspartame, a well-known artificial sweetener, is for example present in thousands of food products worldwide. © Mathilde Touvier/Inserm

Artificial sweeteners are used to reduce the amounts of added sugar in foods and beverages, thereby maintaining sweetness without the extra calories. These products, such as diet sodas, yoghurts and sweetener tablets for drinks, are consumed by millions of people daily. However, the safety of these additives is the subject of debate. In order to evaluate the risk of cancer linked to them, researchers from Inserm, INRAE, Université Sorbonne Paris Nord and Cnam, as part of the Nutritional Epidemiology Research Team (EREN), analyzed data relating to the health of 102,865 French adults participating in the NutriNet-Santé cohort study and their consumption of artificial sweeteners. The results of these statistical analyses suggest a link between the consumption of artificial sweeteners and an increased risk of cancer. They have been published in PLOS Medicine.

Given the adverse health effects of consuming too much sugar (weight gain, cardiometabolic disorders, dental caries, etc.), the World Health Organization (WHO) recommends limiting free sugars1 to less than 10% of one’s daily energy intake2. Therefore, in order to ensure that foods maintain that sweet taste so sought after by consumers worldwide, the food industry is making increasing use of artificial sweeteners. These are additives that reduce the amount of added sugar (and calories) without reducing sweetness. What is more, in order to enhance flavor, manufacturers use them in certain products that traditionally contain no added sugar (such as flavored potato chips).

Aspartame, a well-known artificial sweetener, is for example present in thousands of food products worldwide. While its energy value is similar to that of sugar (4 kcal/g), its sweetening power is 200 times higher, meaning that a much smaller amount is needed to achieve a comparable taste. Other artificial sweeteners, such as acesulfame-K and sucralose, contain no calories at all and are respectively 200 and 600 times sweeter than sucrose.

Although several experimental studies have pointed to the carcinogenicity of certain food additives, there are no robust epidemiological data supporting a causal link between the everyday consumption of artificial sweeteners and the development of various diseases. In a new study, researchers sought to examine the links between the consumption of artificial sweeteners (total and most often consumed) and the risk of cancer (global and according to the most common types of cancer) in a vast population study. They used the data provided by 102,865 adults participating in the NutriNet-Santé study (see box below), an online cohort initiated in 2009 by the Nutritional Epidemiology Research Team (EREN) (Inserm/Université Paris Nord/CNAM/INRAE), which also coordinated this work.

The volunteers reported their medical history, sociodemographic data and physical activity, as well as information on their lifestyle and health. They also gave details of their food consumption by sending the scientists full records of what they consumed over several 24-hour periods, including the names and brands of the products. This made it possible to accurately evaluate the participants’ exposure to additives, and more particularly to artificial sweeteners.

After collecting information on cancer diagnoses over the NutriNet-Santé study period so far (2009-2021), the researchers conducted statistical analyses in order to study the links between the use of artificial sweeteners and the risk of cancer. They also took into account various potentially confounding factors, such as age, sex, education, physical activity, smoking, body mass index, height, weight gain over the study period so far, family history of cancer, as well as intakes of energy, alcohol, sodium, saturated fatty acids, fiber, sugar, whole grain foods and dairy products.

The scientists found that compared with those who did not consume artificial sweeteners, those who consumed the largest amounts of them, especially aspartame and acesulfame-K, were at increased risk of developing cancer, irrespective of the type.

Higher risks were observed for breast cancer and obesity-related cancers.

In accordance with several in vivo and in vitro experimental studies, this large-scale, prospective study suggests that artificial sweeteners, used in many foods and beverages in France and throughout the world, may represent an increased risk factor for cancer,” explains Charlotte Debras, PhD student and lead author of the study. Further research in other large-scale cohorts will be needed in order to replicate and confirm these findings.

These findings do not support the use of artificial sweeteners as safe alternatives to sugar, and they provide new information in response to the controversy regarding their potential adverse health effects. They also provide important data for their ongoing re-evaluation by the European Food Safety Authority (EFSA) and other public health agencies worldwide,” concludes Dr. Mathilde Touvier, Inserm Research Director and study coordinator.

NutriNet-Santé is a public health study coordinated by the Nutritional Epidemiology Research Team (EREN, Inserm / INRAE / Cnam / Université Sorbonne Paris Nord) which, thanks to the commitment and loyalty of over 170,000 participants (known as “Nutrinautes”), advances research into the links between nutrition (diet, physical activity, nutritional status) and health. Launched in 2009, the study has already given rise to over 200 international scientific publications. In France, new participants are currently being encouraged to join in order to continue to advance research on the relationship between nutrition and health.

By devoting a few minutes per month to answering various online questionnaires relating to diet, physical activity and health, participants contribute to furthering knowledge of the links between diet and health. With this civic gesture, we can each easily participate in research and, in just a few clicks, play a major role in improving the health of all and the wellbeing of future generations. These questionnaires can be found on the secure platform


1 Sugars added to foods and beverages and sugars naturally present in honey, syrups, and fruit juices.

2 World Health Organization, 2015

Persistence of severe hepatic fibrosis despite substantial weight loss with bariatric surgery

stéatose hépatique.

Detail of a steatosis, accumulation of a fat, triglyceride, in the liver cell. © Inserm/Hadchouel, Michelle

A research team from AP-HP, Inserm and Sorbonne University carried out work, within the IHU ICAN, on the effects of bariatric surgery on the severity of liver damage in patients with NASH (Non-Alcoholic Steatohepatitis or Metabolic Steatohepatitis) and severe fibrosis (bridge fibrosis or compensated cirrhosis). This study shows that in 50% of patients who underwent bariatric surgery, despite significant weight loss (20% to 30% of initial BMI) and improvement in metabolic risk factors (mainly type 2 diabetes), severe fibrosis persists in the medium term (5 years after surgery). The results of this work were published on January 25, 2022 in the journal Hepatology .

Obesity in France concerns 17% of the adult population and it increasingly affects children and adolescents. It has many consequences on the state of health of people who are affected, including the development of “fatty liver” (liver steatosis). Hepatic steatosis is defined by the accumulation of fat in liver cells favored by the presence of metabolic risk factors (particularly diabetes and obesity).

In France, liver steatosis affects 18% of the population and 25% of the general population worldwide. Eventually, this pathology, also called NASH, can lead to the appearance of more serious diseases such as cirrhosis or liver cancer. To date, there is no effective drug treatment for NASH, which makes research around other avenues of care for patients all the more important.

Previous work has shown dramatic improvement in NASH liver damage after bariatric surgery in parallel with weight loss. Nevertheless, efficacy data in patients with advanced forms of NASH remain limited.

The study, coordinated by Dr Raluca Pais (AP-HP, IHU ICAN), Dr Judith Aron-Wisnewsky (AP-HP, Inserm, Sorbonne University, IHU ICAN), Pr Vlad Ratziu (AP-HP, INSERM, Sorbonne University, IHU ICAN) and Pr Karine Clément (AP-HP, Inserm, Sorbonne University, NutriOmic Unit), analyzed the effects of bariatric surgery on the evolution of severe histological lesions of NASH. The patients, from the “BARICAN bariatric surgery” cohort coordinated by the nutrition department led by Pr Jean-Michel Oppert at the Pitié-Salpêtrière AP-HP hospital, had an initial liver biopsy at the time of surgery. bariatric and a follow-up biopsy.  

This study confirms the excellent results of bariatric surgery: overall, 29% of patients had normal histology at follow-up biopsy; 74% had NASH resolution without fibrosis progression; 70% had fibrosis regression.

However, in patients with severe fibrosis before surgery, severe fibrosis persisted in 47% of cases in the medium term after surgery, despite the resolution of NASH in 69% of cases.

Patients who do not respond to bariatric surgery have a lesser improvement in metabolic risk factors (less weight loss, remission of diabetes) even if clinically significant. The factors associated with the persistence of fibrosis after bariatric surgery, in addition to the follow-up interval, were age and type of surgery (less regression of fibrosis after the sleeve regardless of weight loss). The factors associated with the absence of liver lesions after bariatric surgery were greater weight loss, improved insulin resistance and less initial severity of necroinflammatory lesions.

In conclusion, Dr. Raluca Pais specifies that “ this study shows that, despite established efficacy for the regression of NASH, bariatric surgery is less effective for the regression of severe fibrosis. Fibrosis regression requires more time and probably additional mechanisms. Weight loss alone may not be enough to reverse severe fibrosis. »

Improvement in the Health of Two Infants with Severe Disharmonious Overgrowth Syndromes

Co-labeling of mouse skin expressing a PIK3CA gene mutation. © Marina Firpion/Guillaume Canaud – Inserm unit 1151


Disharmonious overgrowth syndromes are rare genetic diseases associated with a PIK3CA gene mutation. Since 2016, a team of researchers from Inserm, Paris Public Hospitals Group (AP-HP), Université de Paris, the Disharmonious Overgrowth and Vascular Abnormalities Unit of Institut Necker-Enfants Malades and the clinical departments of Hospices Civils of Lyon has demonstrated the therapeutic efficacy of alpelisib, a molecule used to fight certain cancers, in treating a group of children and adults with severe forms of these diseases. In a new publication, the team reports clinical, biological, and imaging improvements in two infants with severe forms of disharmonious overgrowth syndromes treated with alpelisib. These are the first data obtained on the use of this molecule in severe neonatal forms of the disease. The results of this one-year follow-up have been published in Journal of Experimental Medicine (JEM).

Disharmonious overgrowth syndromes are rare genetic diseases characterized by an increase in both the size and number of cells in the body. They manifest by an asymmetry that can affect any body part or tissue (fat, vessels, muscles, bones, etc.), including the brain. In 95% of cases, the disease is linked to a mutation, occurring during embryonic development, of the PIK3CA gene that regulates cell growth and proliferation.

When PIK3CA is overactivated, the parts of the body affected by the mutation grow excessively, leading to physical deformities that are more or less debilitating depending on the number of tissues affected. While some symptoms can be alleviated by surgery and other supportive care, there is currently no approved drug treatment for the disease.

In previous research, the drug alpelisib, a PIK3CA inhibitor recently approved for the treatment of certain forms of breast cancer1, had shown promising results – first in animal models of overgrowth syndrome, and then in a small number of adults and children. The drug is currently undergoing a series of larger-scale clinical trials, but until now there had been no data on its efficacy in infants.

In this new study, a team of researchers from Inserm, Paris Public Hospitals Group (AP-HP) and Université de Paris, coordinated by Professor Guillaume Canaud, reports encouraging results with alpelisib administered for one year to two infants – one girl and one boy aged 8 months and 9 months, respectively, at the start of treatment – presenting with a variety of severe symptoms caused by PIK3CA gene mutations. These symptoms included extreme blood vessel malformations, anemia, excessive asymmetric growth of the limbs and fingers and, in the boy, excessive growth of one of the brain hemispheres (hemimegaloencephaly) associated with epileptic seizures2. Before the start of treatment, the girl’s condition was life-threatening and the boy had a serious neurological prognosis, which did not respond to conventional epilepsy drugs.

Good tolerability

In both infants, daily oral doses of 25 mg alpelisib led to rapid and significant clinical improvement in the symptoms. Twelve months of treatment stopped the boy’s epileptic spasms and reduced the girl’s number of vascular malformations. The considerable decrease in the volume of her right leg has enabled her to remain upright and walk, with assistance. The anemia resolved in both children following initiation of the treatment.

The infants’ length and weight that initially were outside the norm for their age corrected themselves following the introduction of alpelisib. It is important to note that they had no side effects related to the treatment. Further analyses revealed that with a dose of 25 mg per day, their blood levels of alpelisib were much lower than those safely tolerated by adults3.

“The results of the alpelisib treatment in these two infants are encouraging because they show an improvement across all parameters, whether clinical, biological, or radiological. The high level of efficacy observed may be because alpelisib was started early. The patients had no history of surgery, which is relevant because we know that the remodeling caused by it can affect how well alpelisib is absorbed by the tissues. Furthermore, it is very likely that the plasticity of the tissues at this age enables the treatment to work better, explains Professor Canaud, coordinator of the study. These results should however be interpreted with caution and be confirmed over time and with further monitoring,” he says.

This use of alpelisib in overgrowth syndromes continues to be the subject of clinical trials in a population of consisting not just of adults but also of children from 6 years of age. These encouraging results make it possible to envisage extending the drug’s approval to include the clinical treatment of severe neonatal forms.

The treatment of these infants with alpelisib is provided as part of a compassionate use program, in which the French medicines agency (ANSM) issues exceptional approval to treat patients suffering from diseases with a severe prognosis and with no appropriate treatment available, in a given therapeutic indication.


1 The PIK3CA gene is frequently mutated in a certain number of cancers. This mutation is believed to occur in approximately 40% of breast cancers.

2 The boy had West syndrome, also known as infantile spasms, a rare form of epilepsy in infants.

3 When treating cancer, the daily dose of alpelisib administered to an adult (between 300 and 350 mg) is approximately 15 times higher.

Cohort study identifies genetic cause for rare form of diet-induced Cushing syndrome

Coupe de rein humain grossie 400 fois par un microscope à immunofluorescence polychromatique

Human kidney section magnified 400 times by a polychromatic immunofluorescence microscope. © Inserm/Oriol, Rafael


The team made up of researchers from the endocrinology and reproductive diseases department of Bicêtre AP-HP hospital, Inserm and Paris-Saclay University, carried out work, coordinated by Professor Peter Kamenický, to study the genetic cause of bilateral macronodular adrenal hyperplasia with diet-induced Cushing’s syndrome. This rare disease affects the two adrenal glands located above the kidneys and causes an overproduction of cortisol, a steroid hormone whose excess has harmful consequences for the body . Researchers were able to determine the molecular explanation for the occurrence of this disease 30 years after its initial description. This work was published on October 13, 2021 in the journal The Lancet Diabetes & Endocrinology .

This rare form of adrenal Cushing syndrome, studied by these researchers, is due to the abnormal expression of the GIP receptor (Glucose-dependent insulinotropic peptide) in both adrenal glands of patients. GIP is a hormone produced by the small intestine in response to the ingestion of food. In patients with this particular form of Cushing’s syndrome, cortisol levels increase abnormally after each food intake. Patients with this disease develop the typical clinical signs of Cushing’s syndrome such as weight gain associated with muscle atrophy, high blood pressure, diabetes mellitus, osteoporosis, and depression. The pathology is associated with an increase in mortality, especially cardiovascular causes.

In this international study involving researchers from six countries, and based in particular on close Franco-Quebec collaboration, the team reports that GIP-dependent macronodular hyperplasia of the adrenals, in both familial and sporadic forms, is a genetic disease caused by germline mutations of Lysine Demethylase 1A (KDM1A) with secondary loss of the second KDM1A locus, comprising the second copy of the gene, in adrenal tissue. KDM1A acts mainly as a transcriptional repressor (ie a regulator which prevents a gene from being expressed), the loss of its function results in deregulation of the expression of various genes in the adrenal tissue, including the GIP receptor but also of other receptors coupled to G proteins.

This discovery will make it possible to offer genetic counseling and earlier detection of this rare disease to patients and their relatives. Rare diseases are generally underdiagnosed. This is all the more important as the pathogenic variations of KDM1A also predispose to myeloma and other types of cancer.

In addition, this new role of KDM1A as an epigenetic regulator of the expression of the GIP receptor and other receptors coupled to G proteins could have pharmacological implications.