Bottled, tap, filtered, or well water: not all water is the same when it comes to origin (groundwater, surface water, etc.), treatment (filtration, disinfection, etc.), and therefore chemical, mineral, or microbial composition. Despite being consumed in far greater quantities than food, water is often overlooked when it comes to scientific studies on diet and the microbiota. The effects of certain foods (dark chocolate, avocado, tea, etc.) and beverages (soda, alcohol, beet juice, etc.) have been studied carefully, but scientists have been reluctant to look at the role played by water.

A qualitative effect...

The results? The source of our drinking water is a key factor behind variations in the composition of the gut microbiota. Its influence is comparable to that of alcohol consumption or diet. Each type of water consumed corresponds to a different gut microbiota signature. Do you mainly drink well water? Your gut microbiota is likely to be more diverse than if you drink tap, filtered, or bottled water. Moreover, your digestive tract probably hosts more bacteria from the genus Dorea and fewer Bacteroides, Odoribacter and Streptococcus. What’s behind the difference? It may be because well water has greater microbial diversity than tap water due to the lack of systematic disinfection.

... and a quantitative effect

But it’s not all about where our water comes from. Quantity also plays a role. The gut microbiota of low water drinkers (from all sources) differs from that of high water drinkers. For example, low water drinkers have a greater abundance of Campylobacter, a bacterium associated with gut infections. This should encourage us to lift our glass more... provided we’re only drinking water!

“Endometriosis: 4,000 years of prejudice and misdiagnosis”

Dr. Erick Petit

When was endometriosis first described? 

Erick Petit: The disorder has been plaguing the lives of women for 4,000 years... yet it was only recognized as an illness a century and a half ago ! The first officially recorded “patient” was an Egyptian woman in 1855 BC. We can find references to endometriosis as far back as the 6th and 5th centuries BC, posited by Hippocratic physicians who listed the symptoms in detail. After that period, we can observe what appears to have been a kind of medical cover-up. Until the Renaissance, endometriosis was judged to be nothing more than an element of the feminine psyche.

This is supported by the etymology. The word “uterus” originates from the Greek hysterikos and the medical profession was quick to establish the diagnosis of “hysteria”. The illness was seen to be an imaginary condition entirely made up by women, who were actually in agony. It is difficult to believe that it was not until 1860 that the condition was shown to be related to the endometrium (sidenote: Endometrium The layer of tissue that lines the uterus.  NCI Dictionaries_Endometrium   ) , hence the name endometriosis¹, by Carl von Rokitansky, a Bohemian pathologist working in Vienna. It is currently estimated that at least one in ten women of reproductive age suffers from endometriosis. It is in fact more likely to be one in seven, or even one in five, women of reproductive age².

How is endometriosis diagnosed? Why is it so complicated?

E.P.: In reality, the diagnosis is quite simple: patients fill out the clinical questionnaire that I drew up, which is available to them at their appointments in RESENDO (French network). It contains a number of questions, some of which concern the types of pain experienced. I can make a reliable diagnosis based on the results of this questionnaire. The diagnosis is in fact confirmed nine times out of ten. This saves time and is also reassuring for the patient. Today, the way to identify endometriosis is through talking and listening to patients. There are women who have been waiting for a diagnosis for so many years, over a decade in some cases²! They are still victims of prejudices that date back 4,000 years, according to which women’s periods are naturally painful. I have set out to dispel this myth and highlight the fact that endometriosis is a medical condition.

The next step, what I would call the gold standard test is, of course, an endovaginal ultrasound carried out by a specialist (or an MRI (sidenote: MRI Magnetic Resonance Imaging. ) for young girls who have never had sexual intercourse, although this technique is less sensitive and less specific). This test shows the lesions and their locations. However, I would like to stress that medical imaging alone is not enough. There is actually no correlation between symptoms and lesions with this illness. This means that some women can have very extensive endometriosis yet hardly suffer, but conversely, others with much milder endometriosis may experience extreme pain. 

Do different forms of endometriosis exist? Are some forms more serious than others?

E.P.: There are as many forms as there are patients! This is why it is so important to properly map out their pain to fine-tune the diagnosis and treatment. The main consequence of this illness is infertility, depending on the location of the lesions. We have observed a correlation between the anatomic extent of the condition and fertility. But this is not necessarily linked to pain. Endometriosis is the number one cause of hypofertility!²

What are the early signs?

E.P.: The illness appears after the first menstrual period. A young girl should be carefully observed at this time in order to assess the intensity of the pain, to see if she has to go lie down, if she is not able to attend classes, etc. We know that periods starting early, before the age of 11, represent a risk factor for the illness, as well as having a mother or sister who also suffers from the condition (genetic factors). This is why I campaign for raising awareness about endometriosis among girls aged between 11 and 13. This is the only way to ensure cases are not left undiagnosed. There are also effects on digestion that should not be neglected: the near-majority of my patients suffer from some form of irritable bowel syndrome. It is therefore important to make gastroenterologists aware of the illness!

What is patient care based on?

E.P.: Treatment is still very inadequate and is based on a multidisciplinary approach:

“The gut microbiota, undoubtedly a missing piece in the endometriosis puzzle”

Vanessa Gouyot 

Is there a link between endometriosis and the microbiota? 

Vanessa Gouyot: To date, no scientific studies have been conducted that confirm any links between endometriosis and imbalances within the various microbiota (intestinal, vaginal for example) in the human body. However, there are certain clinical signs that support this hypothesis. We now know that 90% of women affected by endometriosis also suffer from associated digestive disorders (irritable bowel syndrome in particular). This figure is borne out in my practice where I am seeing more and more patients who appear to be experiencing gut imbalance, called dysbiosis, in the digestive tract: sometimes oral, sometimes gastric and/or intestinal dysbiosis (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232.   ) .

The role of our microbiota is to protect us and form a barrier. But if 90% of women suffering from endometriosis have digestive disorders, that means that there is an associated inflammation of the digestive system... My mission is to enable my patients to understand that the digestive tract is a passage which is permanently under assault (by food and drink, among other things). This aggression may alter the digestive system and lead to inflammation. The human body should be seen as a big emergency response center regularly sending out units to provide aid.

However, if all the units are dispatched to handle a permanent case of inflammation in the gut, then they cannot respond to all the other alerts. All these alerts form a “background noise” of inflammation, i.e., chronic inflammation, which is thought to facilitate the onset of other conditions, such as endometriosis.

Given the digestive system symptoms observed in patients suffering from endometriosis, could the microbiota help diagnose the illness more quickly?

V.G.: Endometriosis is an inherently complex illness that is particularly difficult to diagnose and should be handled with great humility and some caution. The mechanisms of the illness have inspired numerous hypotheses but it has not yet been possible to determine which is the closest to reality. The role of the microbiota is one hypothesis among many. The fact is that research into the microbiota is moving forward and this is bringing much hope to patients, but we should not get ahead of ourselves. Something to consider is that rather than attempt to assess cases of endometriosis via the microbiota, we could instead assess the microbiota to make a better diagnosis of patients’ bowel inflammation and their digestive disorders³. Endometriosis care requires a global and multidisciplinary approach.

Today, when taking on a new patient suffering from endometriosis, we investigate the finer details of her diet, what she drinks and also her living environment. These are all factors that could prove aggressive to the digestive system and lead to an imbalanced gut microbiota.

Could the microbiota be useful in the search for future treatments?

V.G.: Progress has been made in research on the microbiota^4,5 and this will, in time, significantly improve the quality of life of patients with endometriosis who suffer from digestive disorders⁶. In the meantime, as we wait for future medical breakthroughs, taking probiotics remains one way to restore normal gut microbiota function and reduce inflammation. The problem is the lack of information. Some of my patients do not see probiotics as necessary, others take them sporadically, and then others come back to me to say that they do not work.

Different cases require specific explanations for each patient. Remember that the context is important when taking probiotics and recommendations from an expert are required. There are very many strains of probiotics that can have beneficial effects on endometriosis. The objective of probiotic therapy is to give our patients the tools to manage their condition, so that they become more attentive to signals from their body and so that they can finally achieve acceptable levels of comfort. Getting them back to a normal life with less pain is the ultimate victory for us.

“Yes, diet can relieve a painful digestive system associated with endometriosis”

Dr. Laetitia Viaud Poubeau

Can a healthy diet help to restore balance to the gut microbiota of women suffering from endometriosis? 

Laetitia Viaud Poubeau: In cases of endometriosis, a Mediterranean-type diet, i.e. a diet rich in vegetables, fruits, pulses, and whole grains, but also Omega-3 fatty acids, which are both prebiotics and anti-inflammatory, can only be beneficial to the gut microbiota. A diet like this with anti-inflammatory properties promotes the development of eubiotic flora (sidenote: Eubiotic flora A “balanced” flora.  Iebba V, Totino V, Gagliardi A, et al. Eubiosis and dysbiosis: the two sides of the microbiota. New Microbiol. 2016 Jan;39(1):1-12. ) , rich in bifidobacteria and lactobacilli^7-9.There are many benefits to this type of diet: it helps to restore balance to the gut microbiota, combats intestinal permeability effectively and thereby reduces inflammation.

What foods should be avoided by endometriosis patients?

L. V.-P.: What we refer to as the “Western diet”^8,10, a diet rich in processed foodstuffs, refined sugar, salt, saturated fats (red meat for example) and trans fat (such as pastries),¹¹ is particularly bad for the gut microbiota. The Western diet can cause gut dysbiosis that leads to varying levels of complications in the body over time. Strong alcoholic beverages and drinks like sodas, syrups, and fruit juice should also be added to this list of foodstuffs to avoid because they are particularly rich in sugar and/or sweeteners. Some studies also demonstrate the benefits of reducing the amount of gluten in the diet, since it is thought to contribute to the inflammation involved in the illness.^8,12,13

On the other hand, opinion is more divided when it comes to the consumption of dairy products. They do not appear to put people at a higher risk of developing endometriosis^14,15. The levels of growth hormones that they contain may, however, be conducive to hyperestrogenism (sidenote: Hyperestrogenism Normal or high levels of estrogen secretion, but which continues for longer than the secretion of progesterone.  Norman Lavin (1 April 2009). Manual of Endocrinology and Metabolism. Lippincott Williams & Wilkins. p. 274. ISBN 978-0-7817-6886-3. Retrieved 5 June 2012 ) in patients suffering from endometriosis¹⁶. Additionally, hypersensitivity to milk proteins maintains a “background noise” of inflammation⁸: this means permanent, chronic inflammation. 

Additives, antibiotics used in the agri-food industry, endocrine disruptors, pesticides, and other chemical pollutants that we find in our food should also be treated with caution because they can affect the balance of our microbiota.

What are the consequences of a Western-style diet on the gut microbiota? What are the dietary alternatives?

L. V.-P.: Gut dysbiosis caused by the Western diet will result in intestinal discomfort, which can range from constipation to diarrhea. In many women suffering from endometriosis, we have also observed bloating, intestinal spasms and flatulence that can be odorous to varying degrees. 

We then recommend a FODMAP (sidenote: “Fermentable Oligo- Di- Monosaccharides and Polyols”: Fermentable carbohydrates. ) -free or digestive-sparing diet in order bring quick relief to patients¹⁷. The digestive-sparing diet is based on a set of simple dietary and lifestyle rules: excluding raw vegetables, raw fruits, lactose, gluten, irritant beverages like coffee, strong alcohol and sodas, limiting citrus fruits and cruciferous vegetables, etc. It can be followed for 4 to 6 weeks, is less restrictive than the FODMAP-free diet, and above all does not alter the balance of the gut flora¹⁸.

They support this article:

BMI 22.05

A sleep-brain-gut linkage. That is what a recent study has found. We already knew that in adults, sleep and gut microbiota were doubly interrelated: a deterioration in sleep modifies the composition of the gut microbiota and, conversely, the microbial composition of the gut impacts sleep. But we did not previously know the age at which this two-way link became established between sleep and gut microbiota, or what the potential consequences on development might be.

This was what justified this longitudinal study involving 162 healthy infants at 3, 6, 12 and 24 months of age.

There is a connection between sleep and gut microbiota as early as 3 months of age

First confirmation: the composition of the gut microbiota does indeed start to change as of 6 months of age. The majority of the children in the study experienced a change in flora which went from predominantly Bifidobacterium (enterotype A) to a microbiota rich in Bacteroides (enterotype B), with increased alpha diversity (sidenote: α diversity A measurement indicating the diversity of a single sample, i.e. the number of different species present in an individual. Hamady M, Lozupone C, Knight R. Fast UniFrac: facilitating high-throughput phylogenetic analyses of microbial communities including analysis of pyrosequencing and PhyloChip data. ISME J. 2010 Jan;4(1):17-27. ) .

Above all, the study demonstrates a link between sleep habits and gut microbiota from as early as 3 months: 

• Daytime sleep (duration, number of naps and their regularity) has a negative association with bacterial diversity: infants who sleep the most during the day have less bacterial diversity;
• Nighttime sleep fragmentation and variability are linked to bacterial maturity and enterotype: infants with more mature gut microbiota have higher levels of activity at night (waking up more often during the night). Additionally, their enterotype does not change from enterotype A to B between the ages of 6 and 12 months.

Sleep, brain and gut: all linked?

The brain activity analyzed using the nighttime electroencephalograms at the age of 6 months proved to be rich with useful findings. 

First finding: infants with predominantly Bifidobacterium flora showed less slow-wave sleep (“light sleep”);
Second finding: the quality of sleep at 6 months of age can be used to predict the bacterial diversity of the gut microbiota at age 1. The presence of more theta waves at 6 months is a sign that there will be lower bacterial diversity at 12 months.

Lastly, the gut microbiota at 6 months and above all sleep at 6 and 12 months of age predict the behavioral development of the child at 24 months.

“Twinkle, Twinkle, Little Star”, “Rock-a-Bye Baby”, ““Puff the Magic Dragon”... Every night, you go through your repertoire of lullabies to send your child off to sleep. All in vain. Far from falling asleep, your adorable tot claps its hands and feet, and its wide-open eyes plead to hear you sing. It even seems to want an “encore”! But at what point will your baby finally sleep all through the night? Great news: there are ways to make sure your baby sleeps like a log from dusk to dawn. These solutions seem to involve the gut microbiota, the community of microorganisms in the digestive system, whose composition evolves during the first years of life.

Sleep: bacteria involved from three months

Recent studies carried out on more than 160 infants have shown a link between an infant’s gut flora and its sleeping habits. Infants who slept more during the day had lower gut microbial diversity than those who saved their sleep for nighttime. Moreover, the quality of infants’ nighttime sleep seems to depend on the type of bacteria present in their gut and on the maturity of their gut microbiota. This effect is clear from three months.  This is an important discovery, since up till now these links had only been known in adults.

Influence on future behavior 

Furthermore, brain activity during sleep at six months appears to vary according to the bacteria in the gut. It also appears to predict gut microbial diversity at one year. In short, sleep and microbiota seem closely connected and develop together over time. Should parents of children who have difficulty sleeping be worried?

On the contrary, the authors of the study reassure us that: “Sleep and gut microbiota can be readily modified. Sleep can be tailored with behavioral interventions through educational and behavioral strategies by the parents. Gut microbial composition can be modified by diet or orally ingested prebiotics and probiotics added to infant formula.”

Antibiotic prophylaxis reduces the risk of serious infection in women during delivery by cesarean section by 60–70%². Administration before the incision and not after cord clamping can also reduce the incidence of endometritis and global maternal infectious morbidity³. This approach is now therefore widely recommended, but nevertheless exposes the child to antibiotics before birth, with potential repercussions for his or her health and newly-formed microbiota. Dutch researchers wanted to find out whether it further altered the bacterial colonization of children born by cesarean section.

Dysbiosis in the first month following cesarean birth

Like many others before them, the researchers observed major differences in intestinal flora during the first month of life between the children born by cesarean and those born by vaginal delivery. They recorded a lower Shannon index (relative richness and abundance of species) with a reduction in bacteria from the Bacteroides and Bifidobacterium genera, and an increase in the Proteobacteria phylum, especially Firmicutes. However, these differences resolved by the age of 3 years.

No effects of antibiotic administration prior to incision

The main finding of this study was the absence of any significant difference in composition of the gut microbiota in terms of bacterial phyla or genera between the two groups of children born by cesarean section, at any point between 1 day and 3 years. Although it included only a small group of women, this study suggests that antibiotic prophylaxis prior to incision does not cause any additional disruptions to the intestinal microbiota of children born by cesarean section.

Vaginal human papillomavirus (HPV) is the most common sexually transmitted infection (STI). It is usually asymptomatic. Most of the time, the body eliminates these viruses by itself. However, they can persist in some women, putting them at risk of infections that can lead to cervical cancer. The fourth most common type of cancer among women (sidenote: https://www.who.int/fr/news-room/fact-sheets/detail/human-papillomavirus-(hpv)-and-cervical-cancer ) , cervical cancer is currently incurable and represents a major public health concern.

Dysbiosis of the vaginal microbiota

The risk factors for persistent HPV infections are known: they consist of behavioral (vaginal douching, sexual intercourse) and biological (bacterial vaginosis, bacterial vaginosis, sexually transmitted infections) factors that disturb the vaginal microbiota (dysbiosis). To date, most studies have focused on the link between dysbiosis and precancerous or cancerous lesions of the cervix, but none on the identification of a microbial signature of persistent HPV infection that can be detected before lesions appear, thereby preventing progression to cancer.

Probiotics for prevention?

The analyses showed that HPV infection is associated with a disturbance of the vaginal microbiota, with differences observed between the NC group and groups P and C. The analyses also showed that HPV infection is characterized by depleted bacterial richness and lower bacterial diversity.  Current or past infection is associated with an increase in Firmicutes and Actinobacteriota, and a decrease in Proteobacteria. The authors believe that this dysbiosis facilitates infection by the virus, whereas an increased abundance of vaginal Proteobacteria is thought to stabilize the microbiota. While the vaginal microbiota of all three groups were dominated by lactobacilli, their abundance was even greater in patients who had eliminated the virus (group C) than in NC patients. The researchers also observed a greater abundance of lactobacilli or bifidobacteria species depending on the type of virus eliminated, suggesting that these bacteria have a protective effect against different types of viruses. 

These findings have yet to be confirmed, but the researchers conclude that they pave the way for the development of probiotics which can be used to treat HPV infection early, before malignant lesions of the cervix appear.

Long considered sterile, the uterine cavity is in fact home to a microbiota composed of bacteria. Although 100 to 10,000 times less numerous than the bacteria present in the vagina, uterine bacteria appear to be just as involved in reproductive health. So suggests a multicenter (13 centers located in Europe, America, and Asia), prospective, observational study that analyzed the composition of the endometrial microbiota of 342 infertile women taking part in IVF programs.

Double sampling of endometrial microbiota

Two samples were taken prior to embryo transfer to evaluate the composition of the endometrial microbiota: the endometrial fluid was aspirated from the uterine cavity and the endometrial mucosa was sampled via biopsy. The researchers then studied the relationship between the composition of the endometrial microbiota, analyzed using 16S RNA sequencing, and the outcome of IVF, namely pregnancy carried to term (41% of patients), biochemical pregnancy (8%), miscarriage (8%), or no pregnancy (42%).

Endometrial dysbiosis associated with IVF failure

The researchers observed an increased abundance of Lactobacillus (in fluid and mucosal samples) in patients who carried a pregnancy to term. Conversely, Lactobacillus depletion and the presence of specific pathogenic bacteria, such as Atopobium, Bifidobacterium, Chryseobacterium, Gardnerella, Haemophilus, Klebsiella, Neisseria, Staphylococcus, and Streptococcus, were associated with IVF failure or a pregnancy that did not result in a viable birth. Notably, Gardnerella and Klebsiella were over-represented in both the endometrial fluid and endometrial mucosa of patients whose IVF was unsuccessful.

Lactobacilli, a bulwark against pathogens?

These data point to the role of the endometrial microbiota in the success or failure of embryo implantation and/or the outcome of IVF. The researchers suggest that the outcome of IVF is influenced by the absence of pathogenic bacteria in the endometrium, rather than the presence of beneficial bacteria (such as lactobacilli). Lactobacillus may thus inhibit the colonization of the uterine cavity by pathogenic bacteria. However, further studies are needed to clarify the mechanisms by which these pathogenic bacteria work.

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Is it finally time for endometriosis patients, i.e., one in every 10 women of reproductive age (sidenote: Endometriosis, World Health Organization (2021 March). ) , to come out of the shadows and put an end to diagnostic error? As we enter into Endometriosis Awareness Month and with the announcement by French President Emmanuel Macron on January 11, 2022 of a national strategy (sidenote: https://www.elysee.fr/emmanuel-macron/2022/01/11/strategie-nationale-endometriose ) , the answer is hopefully yes.

Researchers have for some time harbored suspicions about some of our microbiota: not only the vaginal microbiota, which could be a useful predictor of severity, but also, according to one recent Chinese study, the gut microbiota as well as the peritoneal fluid (sidenote: Peritoneal fluid Fluid found in the peritoneal cavity, i.e., inside the membrane surrounding the abdominal organs. It acts as a lubricant, preventing friction between the organs during digestion. DiZerega GS, Rodgers KE, Peritoneal Fluid. The Peritoneum. 1992. pp 26-56 Springer New York ) as tools for confirming the diagnosis.

Peritoneum, gut, and cervix under the microscope 

According to their results, the communities of microbes living in the gut and peritoneum of women with endometriosis differ from those observed in women not affected by this condition. Endometriosis patients have fewer of certain types of protective bacteria (especially Ruminococcus) in the digestive tract, and in contrast an over-representation of pathogenic bacteria (especially Pseudomonas) in the peritoneal fluid. 

On the other hand, the composition of the cervical mucus is relatively similar between women with and without endometriosis.

The gut microbiota, a diagnostic tool? 

Could this difference in the microbiota of the gut and peritoneum in women with endometriosis be used to diagnose the condition earlier? That is the question! Crucially, could this be something thousands of women have until now only dreamed of: a more rapid diagnostic test based on an analysis of the microbiota? In fact, the discovery of an intestinal marker is particularly interesting because a simple stool sample is all that is needed to analyze the gut microbiota. A very promising idea...

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Bacteriophages, or simply “phages,” are the most abundant and varied biological agent on Earth. The natural predators of bacteria, they are ubiquitous in the earth, oceans... and the human intestinal microbiota, where they are the dominant type of virus. Intestinal bacterial dysbiosis, which is associated with gastrointestinal disorders such as Crohn's disease and Irritable Bowel Syndrome, goes hand in hand with compositional changes in the virome.

A century on, and they’re back in the spotlight

In the 1920s, experiments to assess the therapeutic potential of phages gave promising results in patients with shigellosis, dysentery, and cholera. This emerging field of research (sidenote: Summers WC. The strange history of phage therapy. Bacteriophage. 2012 Apr 1;2(2):130-133. ) was then cast aside with the arrival of antibiotics in the 1940s. Although a few studies, unfortunately badly documented ones, continued in Soviet countries, phages were relegated to the second division. However, recent concerns over multidrug-resistant infections, and a new understanding of how antibiotics impact the balance of the intestinal microbiota, have prompted a renewed scientific interest in phage therapy. Each species of phage usually targets a single species of bacteria, which means these viruses can provide a “precision” solution where broad-spectrum antibiotics fall short. Nevertheless, despite its great promise, the health care authorities have yet to authorize any phage-based therapy (except in very exceptional cases).

Antibiotic resistance, dysbiosis, targeted therapy: multiple potential uses 

In 2017, one particular case study (sidenote: Schooley RT, Biswas B, Gill JJ, et al. Development and Use of Personalized Bacteriophage-Based Therapeutic Cocktails To Treat a Patient with a Disseminated Resistant Acinetobacter baumannii Infection. Antimicrob Agents Chemother. 2017 Sep 22;61(10):e00954-17.  ) attracted attention: a 68-year-old diabetic patient with pancreatitis complicated by a multidrug-resistant Acinetobacter baumannii infection regained full health in just five months thanks to phage therapy, after several failed attempts with antibiotics. Similar success stories have been reported with Pseudomonas aeruginosa (sidenote: Jennes S, Merabishvili M, Soentjens P, et al. Use of bacteriophages in the treatment of colistin-only-sensitive Pseudomonas aeruginosa septicaemia in a patient with acute kidney injury-a case report. Crit Care. 2017 Jun 4;21(1):129.  ) and Mycobacterium abscessus (sidenote: Dedrick RM, Guerrero-Bustamante CA, Garlena RA, et al. Engineered bacteriophages for treatment of a patient with a disseminated drug-resistant Mycobacterium abscessus. Nat Med. 2019 May;25(5):730-733. ) , offering hope of a promising alternative for the treatment of multidrug-resistant bacterial infections. Phage therapy as a modulator of the intestinal microbiota is also of interest to scientists. A study in mice found that treatment with phages specific to Enterococcus faecalis, a bacterium associated with a poor prognosis in alcohol-related hepatitis, can improve the disease.

Seeking to overcome the challenges of clinical use 

Research now needs to look at ways to overcome the many questions posed by clinical practice. Is phage therapy always safe? Can it replace antibiotic treatment? What is the best method of administration and the right dose? What is their long-term effect on the microbiota and health in general? According to the authors, randomized, double-blind, placebo-controlled clinical trials are needed to legitimize the role of phage therapy, an age-old practice that could help overcome several of the challenges facing medicine today.

COPD (sidenote: https://www.who.int/news-room/fact-sheets/detail/chronic-obstructive-pulmonary-disease-(copd). ) is a chronic respiratory disease characterized by increasing difficulty in breathing. In its “mild” stage, patients have limited respiratory discomfort. In the “very severe” stage, they are short of breath at the slightest effort – even when at rest – preventing normal activity. Today, we can slow the aggravation of COPD with anti-inflammatory drugs, bronchodilators (sidenote: Bronchodilators Drugs that reduce bronchial obstruction. https://www.who.int/news-room/fact-sheets/detail/chronic-obstructive-pulmonary-disease-(copd) ) , and breathing exercises, but we do not know how to cure it. While smoking and pollution are major risk factors for the disease, its mechanisms remain poorly understood.

However, a link between gut microbiota imbalances and respiratory diseases such as allergic asthma or pneumonia has recently been discovered, part of what scientists refer to as the “gut-lung axis”. Could the gut-lung axis be involved in COPD?

A microbiota imbalance associated with inflammation in patients...

To answer this question, a team of Chinese researchers analyzed the gut microbiota of around a hundred COPD patients at various stages of severity and compared them with the microbiota of healthy subjects. They found that the gut flora of COPD patients differed from that of healthy subjects. Specifically, the bacterial species Prevotella, suspected of exacerbating inflammation, dominated their gut microbiota. In addition, they had lower levels of short-chain fatty acid (SCFAs) (sidenote: Short chain fatty acids (SCFA) Short chain fatty acids (SCFA) are a source of energy (fuel) for an individual’s cells. They interact with the immune system and are involved in communication between the intestine and the brain. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020;11:25. ) , especially the most severely affected patients. SCFAs are produced by bacteria in the microbiota from dietary fiber and are known for their anti-inflammatory properties.

... that increases vulnerability to pollution

The researchers then performed a fecal microbiota transplant from the participants to mice. Four weeks later, the lungs of the mice receiving the transplant showed strong inflammation and mucus hypersecretion. Knowing that COPD is accompanied by hypersensitivity to air pollutants, they then exposed the mice to fuel smoke for 20 weeks. The researchers found that the lung function of these mice deteriorated faster than that of unexposed mice.

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