Early exposure to tobacco as a cause of behavioural problems in children

Researchers from Inserm and Pierre and Marie Curie University (UPMC), in collaboration with the university hospitals of 6 French cities, have analysed data on pre- and postnatal exposure to tobacco in the homes of 5,200 primary school children. They show that this exposure is associated with a risk of behavioural disorders in children, particularly emotional and conduct disorders. The association is stronger when exposure takes place both during pregnancy and after birth. These data show the risk associated with smoking in early life and its behavioural repercussions when the child is of school-going age. These results are published in the journal Plos One.Fotolia_6636690_XS


The consequences of tobacco exposure are widely documented. It leads to many illnesses, including asthma. However, the potential role of environmental tobacco smoke (ETS) is much less well known in terms of its link to behavioural problems in children. In this context, the team led by Isabella Annesi-Maesano, Inserm Research Director at Unit 1136, “Pierre Louis Public Health Institute” (Inserm/UPMC) examined the association between pre- and postnatal ETS exposure and behavioural problems in children.

“Exposure to ETS in the postnatal period, alone or in association with exposure during pregnancy, increases the risk of behavioural disorders in primary school children,” explains Isabella Annesi-Maesano, Inserm Research Director

These data come from the 6 Cities Study (see box), which targeted 5,221 primary school children. Prenatal (in utero smoking) and postnatal exposure to tobacco smoke in the home was assessed using a standardised questionnaire completed by the parents. Behavioural disorders were assessed via the Strengths and Difficulties Questionnaire (SDQ) used to assess the behavioural and psychosocial functioning of the children, which was also completed by the parents.

In greater detail, emotional disorders are associated with exposure to ETS during both the prenatal and postnatal periods, which concerns 21% of the children in the study. Conduct disorders are also associated with ETS exposure in these children. The association also exists in cases of prenatal or postnatal exposure alone, but is less pronounced.

These observations seem to confirm those carried out in animals, i.e. that the nicotine contained in tobacco smoke may have a neurotoxic effect on the brain. During pregnancy, nicotine in tobacco smoke stimulates acetylcholine receptors, and causes structural changes in the brain. In the first months of life, exposure to tobacco smoke generates a protein imbalance that leads to altered neuronal growth.

 “Our data indicate that passive smoking, in addition to the well-known effects on health, should also be avoided because of the behavioural disorders it may cause in children,” concludes the researcher.

Specific objectives of the study

The International Study of Asthma and Allergies in Childhood (ISAAC) is aimed at measuring the frequency and severity of asthma and allergic disease (phase I), determining the risk factors for these diseases (phase II), and studying their progression (phase III).

The French component was carried out in 6 large cities, chosen for their varying air quality (Reims, Créteil, Strasbourg, Clermont Ferrand, Bordeaux and Marseille).

The 6 Cities Study initially enrolled 9,615 children with a mean age of 10 years, distributed among 401 classes in 108 schools.

To analyse exposure to environmental tobacco smoke, 5,221 children were enrolled in this component of the study.

Should I stay or should I go? On the importance of aversive memories and the endogenous cannabinoid system

Memory is not a simple box of souvenirs; it is also, and most importantly, a safety system for organisms. With the help of negative memories, known as “aversive” memories, we can avoid a threat that we have already confronted. Researchers from Inserm and University of Bordeaux have just discovered that the cannabinoid receptors of the brain control these memories that are crucial for survival. This study is published in Neuron.Mouse

© Charlie Padgett

When confronted by danger, every individual has to make a crucial choice. This type of “simple” decision may determine his/her destiny: if the fire alarm goes off, we have learned to heed it and flee, and not to ignore it. In the same way, we avoid food and drinks that might have made us sick in the past.

The body is thus equipped with neurological mechanisms that help it to adjust its behaviour in response to a stimulus. Such is the case with aversive memories, a key survival process, which prepares the body to avoid these potential dangers effectively. These memories are accompanied by physiological responses (fright and flight) that enable one to get away from a dangerous situation.

Although the role of the habenula, a central region of the brain, in this phenomenon has received a great deal of attention in recent years, the same is not true of the endogenous cannabinoid system of the habenular neurons, on which Giovanni Marsicano and his team (particularly Edgar Soria-Gomez) have focused. This system involves the type 1 cannabinoid receptors. These receptors, the activity of which is normally regulated by endocannabinoids – the body’s own molecules – are the target of the main psychoactive components of cannabis.

The researchers conditioned mice so that they reacted to certain danger signals (sounds or smells). When they exposed them to these signals, mice that were deficient in cannabinoid receptors in the habenula expressed neither the fear nor the repulsion observed in normal mice. Interestingly, this impaired reaction did not apply to neutral or positive memories, which remained unchanged in these mice.

At molecular level, the scientists observed that, although the functioning of the habenula normally involves two molecules (acetylcholine and glutamate), the defect observed in these mice is caused by an imbalance in neurotransmission involving only acetylcholine.

“These results demonstrate that the endogenous cannabinoid system in the habenula exclusively controls the expression of aversive memories, without influencing neutral or positive memories, and does so by selectively modulating acetylcholine in the neural circuits involved,” explains Giovanni Marsicano, Inserm Research Director.

The control of these particular memories is an integral part of diseases associated with the emotional process, such as depression, anxiety or drug addiction. As a consequence, the endogenous cannabinoid system of the habenula might represent a new therapeutic target in the management of these conditions.

ENS@T-HT, launch of a large scale Europe H2020 project coordinated by Inserm for improved diagnosis and treatment of arterial hypertension through an omics-based approach

An international group of scientists from 6 countries bring together their expertise to improve diagnosis and therapeutic care for primary and secondary forms of arterial hypertension. ENS@T-HT, which is coordinated by Maria-Christina Zennaro, Research Director at Inserm (Paris Cardiovascular Research Center), was officially launched this month in Paris and will last 5 years.

Hypertension affects up to 45% of the general population and is responsible for 9.4 million deaths per year worldwide. Even small rises in blood pressure are associated with increased risk of stroke and heart disease. However, despite a large array of available treatments, blood pressure is still not properly controlled in many patients.

Approximately 10% of current hypertension cases could be treated and cured if properly diagnosed. These include disorders of the adrenal gland that increase the production of hormones affecting blood pressure. Correct identification of these disorders is crucial to proper management of the underlying disease and prevention of cardiovascular complications. However, due to the complexity of diagnosis, proper treatment of these conditions can be delayed by several years, exposing patients to increased cardiovascular and metabolic risk and diminished quality of life.

ENS@T-HT is a five-year-long European H2020 research project created to tackle these issues. It received funding of €7.6m and involves 13 academic institutions from France, Germany, Italy, the United Kingdom, the Netherlands and Australia.

The main objective is to develop a programme to improve diagnosis of various adrenal forms of hypertension, enabling curative treatments and preventing complications.

This will be achieved using various cutting-edge ‘omics’ techniques to identify biomarkers in patients’ blood that provide a distinctive signature for their condition. Useful biomarkers will also permit the stratification of patients, so that those most likely to benefit from particular treatments are identified in order to maximise the effectiveness and cost efficiency of treatment.

Maria-Christina Zennaro, coordinator of ENS@T-HT (Inserm Unit 970, Paris Cardiovascular research center) says: « The ambition of this project is twofold: first we want to establish omics-derived biomarkers and validate their accuracy in the diagnosis of patients with adrenal forms of hypertension. Second, and most importantly for patients, we want to use these biomarkers to accelerate and optimize the diagnosis and management of these conditions. We can then stratify those patients who could most benefit from specific targeted treatment ».

More detail about ENS@T-HT, a multiple-step-project with access to unique cohorts of patients in Europe

— In an initial exploratory phase partners will establish omics-derived signatures of patients with PA, PPGL and CS through bioinformatics modelling of large datasets derived from multiple platforms.

— The signatures will be validated as stratification biomarkers by establishing reference values and variability in healthy controls.

— They will subsequently be used in a prospective clinical study to identify endocrine forms of hypertension and to stratify patients with arterial hypertension. The usefulness and cost-effectiveness of this approach will be evaluated in comparison to current standard of care outcomes and costs.

ENS@T-HT is based on the exploitation of unique cohorts of patients with PA, PPGL and CS recruited by reference centers for adrenal disorders organized within the European Network for the Study of Adrenal Tumors ENS@T ( ENSAT-HT will take advantage of the prospective collaboration of six European Society of Hypertension ESH Centres of Excellence (, providing a unique capability for the recruitment and workup of a large cohort of hypertensive patients.

Website :

Inserm and CentraleSupélec sign a framework agreement

The twin objective of this new collaboration between the French National Institute of Health and Medical Research (Inserm) and CentraleSupélec is to train engineers that are better integrated into research laboratories, and biologists that are more involved in technological innovation. The two establishments hope to enhance their communal actions through innovation and entrepreneurial spirit; the creation of new businesses will be another aspect of the programme being established.

From 2015, scientific collaborations will be established between Inserm and CentraleSupélec, based on scientific priorities identified jointly by the two establishments. To initiate this partnership, Inserm and CentraleSupélec hope to become involved in the following themes:

– modelling, mathematics, databases and imaging

– microscopy and nanotechnology for biologySignature Inserm/CentraleSupélec

Signature of the framework agreement between Professor Yves Lévy, Chairman and CEO of Inserm, and Hervé Biausser, Director of École CentraleSupélec, at Inserm headquarters in Paris on 21 September 2015. ©Inserm/Heidinger, Jean-Marie

Projects based on these priority themes will be identified by the researchers in both establishments, in order to deploy their complementary assets and advance knowledge in areas of major challenge such as cancer or neuroscience. These projects will give rise to exploratory subjects offered to students during the course of their studies. Thus engineering students will be closer to innovation in a core area of human progress, alongside researchers internationally recognised for their expertise in health-related technologies. The educational component will be complemented by a dual programme in which student trainees will be hosted in Inserm laboratories, and Inserm staff will be offered training modules by CentraleSupélec, particularly in the area of entrepreneurship and business creation via the Centrale Entrepreneur stream.

For Yves Lévy, Chairman and CEO of Inserm, this signing is a reflection of a dynamic and multidisciplinary research landscape in France.

“I am convinced that engineers must be attracted to and trained in biology and medicine, just as biologists and physicians must become more involved in technological innovation. Today, life sciences research could not be imagined without the contributions that come from areas such as physics, mathematics and technology. I am therefore proud of this collaboration with CentraleSupélec, which promises a bright future for French life sciences research.”

French women breastfeed for 4 months on average

According to the World Health Organisation (WHO), exclusive breastfeeding (children only receiving breast milk and no other food or drink) should last until the infant is 6 months old and partial breastfeeding should continue up to 2 years of age. A study conducted by Inserm Unit 1018 “Centre for Research in Epidemiology and Population Health”, and published by the InVs (French Institute for Public Health Surveillance) Bulletin Épidémiologique Hebdomadaire, shows that French women breastfeed for an average of 17 weeks, or just over 4 and a half months in total, and only exclusively for two months.

These data come from the ELFE study organised by Inserm, Ined and the French National Blood Service, which monitored over 18,000 children since 2011. One of the aims was to analyse the duration for full and partial breastfeeding and then determine the sociocultural, demographical and economical factors associated with breastfeeding duration.

Researchers have demonstrated that if breastfeeding duration among women is shorter than the time recommended by WHO, then this observation is particularly true for women under 30 who live alone and have a low level of education.

For the authors of the study “These findings support the need to change the image of breastfeeding and to devise a promotional strategy that targets young mothers with low income and education that are more likely stop breastfeeding early”.

Antimicrobial Film for Future Implants

The implantation of medical devices is not without risks. Bacterial or fungal infections can occur and the body’s strong immune response may lead to the rejection of the implant. Researchers at Unit 1121 “Biomaterials and Bio-engineering” (Inserm/Strasbourg university) have succeeded in creating a film with antimicrobial, antifungal and anti-inflammatory properties. It may be used to cover titanium implants (orthopaedic prostheses, pacemakers…) prevent or control post-operative infections. Other frequently used medical devices that cause numerous infectious problems, such as catheters, may also benefit.

These results are published in the journal Advanced Healthcare Materials.

See video on the discovery presented by Philippe Lavalle, Research Director at Inserm (subtitles soon available)


Implantable medical devices (prosthesis/pacemakers) are an ideal interface for micro-organisms, which can easily colonize their surface. As such, bacterial infection may occur and lead to an inflammatory reaction. This may cause the implant to be rejected. These infections are mainly caused by bacteria such as Staphylococcus aureus, originating in the body, and Pseudomonas aeruginosa. These infections may also be fungal or caused by yeasts. The challenge presented by implanting medical devices in the body is preventing the occurrence of these infections, which lead to an immune response that compromises the success of the implant. Antibiotics are currently used during surgery or to coat certain implants. However, the emergence of multi-resistant bacteria now restricts their effectiveness.

A film invisible to the naked eye…

It is within this context that researchers at the “Bioengineering and Biomaterials” Unit 1121 (Inserm/Strasbourg University) with four laboratories[1] have developed a biofilm with antimicrobial and anti-inflammatory properties. Researchers have used a combination of two substances: polyarginine (PAR) and hyaluronic acid (HA), to develop and create a film invisible to the naked eye (between 400 and 600 nm thick) that is made of several layers. As arginine is metabolised by immune cells to fight pathogens, it has been used to communicate with the immune system to obtain the desired anti-inflammatory effect. Hyaluronic acid, a natural component of the body, was also chosen for its biocompatibility and inhibiting effect on bacterial growth.

illustration implant Inserm en

…with embedded antimicrobial peptides,

The film is also unique due to the fact that it embeds natural antimicrobial peptides, in particular catestatin, to prevent possible infection around the implant. This is an alternative to the antibiotics that are currently used. As well as having a significant antimicrobial role, these peptides are not toxic to the body that they are secreted into. They are capable of killing bacteria by creating holes in their cellular wall and preventing any counter-attack on their side.

…on a thin silver coating,

In this study researchers show that poly(arginine), associated with hyaluronic acid, possesses microbial activity against Staphylococcus aureus (S. aureus) for over 24 hours. “In order to prolong this activity, we have placed a silver-coated precursor before applying the film. Silver is an anti-infectious material currently used on catheters and dressings. This strategy allows us to extend antimicrobial activity in the long term” explains Philippe Lavalle, Research Director at Inserm.

…effectively reducing inflammation, preventing and controlling infection

The results from numerous tests performed on this new film shows that it reduces inflammation and prevents the most common bacterial and fungal infections.

On the one hand, researchers demonstrate, through contact with human blood, that the presence of the film on the implant suppresses the activation of inflammatory markers normally produced by immune cells in response to the implant. Moreover, “the film inhibits the growth and long-term proliferation of staphylococcal bacteria (Staphylococcus aureus), yeast strains (Candida albicans) or fungi (Aspegillus fumigatus) that frequently cause implant-related infection” emphasises Philippe Lavalle.

Researchers conclude that this film may be used in vivo on implants or medical devices within a few years to control the complex microenvironment surrounding implants and to protect the body from infection.

This work received the financial support from Institut Carnot MICA and from European Commission with the “Immodgel” project.

[1] The society Protip Medical, Heidelberg university, Institut de physique et chimie des matériaux de Strasbourg (CNRS/ Strasbourg university) and Institut Charles Sadron (CNRS)

Malaria: multi-drug resistance more alarming than ever

The efforts of the international community for the past ten years in the fight against malaria have reduced the number of disease-related deaths. The emerging resistance to standard therapies threatening South-East Asia, and new research carried out by the team led by Françoise Benoit-Vical, Inserm Research Director in the CNRS (French National Centre for Scientific Research) Coordination Chemistry Laboratory in collaboration with the Pasteur Institute and Inserm, are not reassuring factors. The in vitro examination of a strain of parasites solely exposed to artemisinin (the base compound for standard therapy) demonstrates the development of a widespread resistance to most other anti-malarial drugs. This new resistance cannot be detected by tests currently used and represents an additional threat to antimalarial treatments in the field.This research is published in the journal Emerging Infectious Diseases.

Malaria is caused by a parasite propagated through bites from infected mosquitoes from the Anopheles genus. This disease is most prevalent in tropical areas and still responsible for over 600,000 deaths each year. Policies to combat this disease have led to a 60% decrease in mortality over 15 years. However, artemisinin, the pharmaceutical base compound for antimalarial therapies, is encountering increasing clinical failure due to emerging resistance throughout South-East Asia. As of yet, this resistance has not been observed on the African continent.

Artemisinin is an active ingredient from a Chinese plant whose benefits have been known for over 2,000 years. It is used in combination with other antimalarial agents. The value of these combination therapies lies in the assurance that even if the parasite develops a resistance to one molecule, it is less likely to develop a resistance to both molecules.

Scientists must nevertheless stay one step ahead of the parasite, given the recent and rapid development of resistance to artemisinin. It is against this background that the team led by Françoise Benoit-Vical, Inserm Research Director in the CNRS Coordination Chemistry Laboratory in Toulouse, in collaboration with Inserm in Toulouse and the Pasteur Institute in Paris, is studying the resistance mechanisms developed by Plasmodium falciparum, the parasite responsible for malaria, and researching new antimalarial drugs.

Researchers have shown that parasites who survive in vitro in the presence of only artemisinin for five years develop a widespread resistance to most other artemisinin-based or non-artemisinin-based antimalarial therapies, including partner molecules present in combination therapies used in endemic areas.

Scientists have demonstrated that these parasites do not exhibit any known mutation in resistance genes. However, they circumvent the toxic effect of the drugs by a phenomenon known as quiescence. Parasites are capable of suspending their development during exposure to antimalarial agents. As soon as they are no longer subjected to antimalarial therapy, the parasites “wake-up” and proliferate once again.

The new multi-drug resistance based on this quiescence phenomenon cannot be detected by tests currently carried out to analyse parasitic resistance. “In vitro tests carried out using the patient’s blood predict high sensitivity and, therefore, the treatment’s effectiveness, while parasites are resistant because they are quiescent. As such, it is essential to conduct research with relevant and appropriate tests in the field if the multi-resistant phenomenon that we identified in vitro is also present, in order to design therapeutic strategies accordingly.” explains Françoise Benoit-Vical.

The ability of artemisinin-resistant parasites to develop a tolerance to partner drugs is a serious threat to combination therapy.

21 September: World Alzheimer’s Day

Spearheaded by the France Alzheimer’s association, the 22nd edition of the World Day to combat Alzheimer’s Disease will take place on Monday 21 September. The focus this year will be on Alzheimer’s sufferers’ speech.

Since its creation, Inserm has made Alzheimer’s disease one of its priorities. Each year, this neurodegenerative disorder, which results in progressive and permanent deterioration of the nerve cells, engages many teams in the development of new treatments.

Bruno Dubois, Director of the Institute for Memory and Alzheimer’s Disease and Director of the “Cognition, Imaging and Brain Disorders” team notably work on the reasons for the development and progression of the disease through the INSIGHT study.

Furthermore, Inserm, in particular Hervé Platel and his team in Inserm Unit 1077, are dedicating part of their research to the study and benefit of music therapy to help people affected by Alzheimer’s Disease. For further information, see the series of films “Alzheimer’s Allegros” on the Inserm site.

Study of leukaemias in children living close to heavily used roads

Results of the GEOPCAP programme 2002-2007

Inserm researchers from CRESS (Epidemiology and Biostatistics Sorbonne Paris Cité Research Centre, Inserm – Paris Descartes University – University of Paris 13 – Paris Diderot University – INRA) studied the risk of acute leukaemia in children living close to heavily used roads. To address this question, the research team considered all 2,760 cases of leukaemia diagnosed in children under 15 years of age in metropolitan France over the 2002-2007 period. The results show that the incidence of new cases of myeloblastic leukaemia (418 of 2,760 cases of leukaemia) was 30% higher in children in the population whose residence was located within 150 m of heavily used roads, and had a combined length of over 260 m within this radius. In contrast, this association was not observed for the more common, lymphoblastic type of leukaemia (2,275 cases). The researchers particularly studied the case of the Île-de-France region of Paris with the help of data modelled by Airparif, which is responsible for the monitoring of air quality in Île-de-France.

These results are published in the American Journal of Epidemiology.

Cancer affects over 1,700 children under 15 years of age every year in France, which has a population of a little over 11 million children. Surveillance of these cancers has been provided by the French National Registry of Childhood Haematopoietic Malignancies since 1990, and by the French National Registry of Childhood Solid Tumours since 2000. With 470 new cases each year, leukaemias (blood cancers) are the most common childhood cancers, and are mainly acute lymphoblastic leukaemias. “Myeloblastic” or “myeloid” leukaemia is another type of leukaemia, and affects myeloid stem cells, which give rise to the red blood cells. Today, 5-year survival following childhood leukaemia is over 80%.

The general objective of the GEOCAP programme (GEOlocation Study of Paediatric CAncers) is to study the role of environmental exposures in the occurrence of cancer in children under 15 years.

One of the hypotheses of the research community is that there is an increased risk of leukaemia in children living close to heavily used roads. The increased risk of myeloblastic leukaemia for adults with a history of occupational exposure to benzene has long been known.

The EPICEA (Epidemiology of Childhood and Adolescent Cancers) team, directed by Jacqueline Clavel, Inserm Research Director, at CRESS, has reported the results of a study on the incidence of leukaemias in children living close to heavily used roads. It is a case-control study that allowed the assessment of exposure level to one or more risk factors. All 2,760 cases of childhood leukaemia diagnosed in metropolitan France between 2002 and 2007 were included in the study, and compared to a contemporary sample of 30,000 control children representative of the metropolitan population, and constituted in collaboration with the French National Institute of Statistics and Economic Studies (INSEE).

“The frequency of myeloblastic type leukaemias was 30% higher in children living within a 150 m radius of heavily used roads, and where the combined length of road sections within this radius exceeded 260 m,” explains Jacqueline Clavel, Inserm Research Director.

In contrast, there was no association between acute lymphoblastic leukaemias – the most common – and the atmospheric concentration of nitrogen dioxide, distance or combined length of heavily used roads in the vicinity of dwellings.

The researchers particularly studied the case of the Île-de-France region of Paris, the most urbanised region, for which the mean annual concentration of benzene, mainly from road traffic, was estimated in the vicinity of each residence in the study in a particularly precise manner with the help of data modelled by Airparif, which is responsible for the monitoring of air quality in Île-de-France. They observed that the risk of childhood acute myeloblastic leukaemia was double in Île-de-France children whose residences were the most exposed to traffic, i.e. when, simultaneously, the combined length of road sections within a 150 m radius of the residence exceeded 300 m, and the estimated mean annual concentration of benzene in the vicinity of the residence was above the median value observed in Île-de-France (1.3 µg/m3).

In keeping with the hypotheses on which the study is based, exposure to benzene related to car traffic might be one of the explanations for this association.

The GEOCAP programme (GEOlocation Study of Paediatric CAncers)

The general objective of the GEOCAP programme is to study the role in the occurrence of cancers in children under 15 of environmental exposures estimated by geocoding, especially:

– high voltage power lines, causing exposure to extremely low-frequency magnetic fields

– road traffic and atmospheric pollution from benzene and polycyclic aromatic hydrocarbons,

– service stations, a source of exposure to benzene

–  nuclear sites

– and some industrial plants.

It also relates to other factors, particularly demographic trends and socioeconomic disparities between residential areas.

More about GEOCAP:

The addresses of the children included in the study were geolocated with the help of a geographic information system based on French National Geographic Institute (IGN) data, exploited in collaboration with the Géocible company.

This work was supported by InVS, ANSES, ARC, Pfizer foundation, INCa and ANR


Intestinal microbiota: a key player in regulating our body’s iron

Do the bacteria in our intestine influence the metabolism of iron, an essential component for a healthy body? For the first time, teams from Inra and Inserm, in collaboration with the CNRS (French National Centre for Scientific Research), have demonstrated how bacteria can alter the distribution and storage capabilities of iron in the intestinal cells. Microbiota may be considered a new pathophysiological regulator in intestinal iron absorption. This research is published online in The Faseb Journal on 15 September 2015.bacterie e.coli

Escherichia Coli, enterobacteria, normal host in the digestive tract. ©Inserm

Iron is a vital element that the body cannot do without. The regulation and control of iron in the body are essential to good health. An iron deficiency can have a negative impact, while an iron overload can also be a health risk. Many societal issues are currently being raised, particularly the effectiveness and the need for people to supplement their diets with iron.

The bacteria that make up the microbiota in the intestine and the intestinal cells live in symbiosis and each require iron to survive. Dietary iron’s only gateway to the body is through the intestine. When the body requires iron, its absorption is promoted by the intestinal cells. The cells also reduce absorption capacity when iron intake needs to be decreased. These defined regulatory mechanisms also respond to the hormone hepcidin, which was discovered several years ago by an Inserm research team.

Researchers at Inra and Inserm, in collaboration with the CNRS, are interested in the effect that the microbiota has on the intestinal absorption of iron, regardless of hormonal effects. To do this, they compared animals (rodents) deprived of intestinal microbiota (“axenic” animals) with animals whose microbiota is controlled. Without the microbiota, intestinal cells have very low iron stores and the transport systems to the body are quite scarce. However, as soon as the microbiota are present in the intestine, the intestinal cells acquire a high iron storage capacity (in the form of ferritin) and promote its transport to the body (increased ferroportin). 

Thus, the intestinal cells adapt their ability to store and distribute iron when microbiota bacteria are present.

The identification of this new pathway for iron metabolism control will lead to better control of iron intake and should help better understand iron anomalies in diseases involving microbiota imbalances called “dysbiosis”.