July 2017 Newsletter

July 2017 Newsletter

It is with a great pleasure that we invite you to read and share this first “Microbiota Newsletter”. Under the auspices of the BMI (Biocodex Microbiota Institute), this document will be released three times a year (two in 2017), it will be available in three languages (English, Spanish and French) and will also be downloadable from the BMI website: 
www.biocodexmicrobiotainstitute.com

The “Microbiota Newsletter” is focused on the importance of the various microbiota. It is intended to be “universal” and will therefore replace the newsletters that were proposed by Biocodex France (“Le Microbiote dans tous ses états”) and by Biocodex International (“Biotascope”). We are very grateful to the authors of the French and international newsletters - in particular Professors Harry Sokol (Paris) and Emmanuel Mas (Toulouse) and Professor Serhat Bor (Turkey), Editor-in-chief, as well as the members of the ISGOP board.

We have decided, as it was the case in the previous formats, to entrust the best world experts with the drafting of the contents.

We hope you will enjoy your reading !

Microbiota and irritable bowel syndrome

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Irritable bowel syndrome (IBS) combines abdominal pain and transit disorders, affects 5-10% of adults in France and is the leading cause of chronic abdominal pain in children. Its pathophysiology is complex with multiple abnormalities reported in the digestive tract and central nervous system (CNS). Microbiota abnormalities with bacterial overgrowth in the small intestine and dysbiosis related to qualitative and/or functional changes of the flora have recently been reported. They could be involved in the various pathophysiological mechanisms described in IBS. Some treatments may be successful through their effect on the microbiota, such as antibiotics, probiotics or dietary measures. The place of fecal transplantation remains to be determined.

Fecal microbiota transplantation from patients with irritable bowel syndrome to mice results in impaired intestinal functions and behavior

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Irritable bowel syndrome (IBS) is a common disorder characterized by an impairment of intestinal functions often associated with anxiety. Although changes in gut microbiota composition have been documented, their relevance to the clinical symptomatology of IBS remains unknown. To assess the functional role of the commensal bacterial microbiota in IBS, the authors have colonized axenic mice (free of microbiota) with the fecal microbiota of healthy subjects or patients with diarrheal IBS (IBS-D), with or without anxiety, and have monitored intestinal functions and behavior in transplanted mice. In recipient mice, the microbiota profiles were grouped according to human donors. Mice that received a fecal microbiota from IBS-D patients had a taxonomic microbial composition similar to that of mice that received a fecal microbiota from healthy subjects.
However, IBS-D mice had a different serum metabolomic profile. Mice with a IBS-D microbiota had an accelerated gastrointestinal transit, a dysfunction ofthe intestinal barrier, an activation of innate immunity and an anxious behavior.
These results indicate that the gut microbiota could contribute to the intestinaland behavioral manifestations of IBS-D and suggest the potential benefit of microbiota-targeted treatments in IBS patients.

Natural history of the gut microbiome in infants and effect of antibiotic treatment on bacterial strain diversity and stability

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The gut microbial community is dynamic during the first 3 years of life, before stabilizing to an adult-like state. However, little is known about the impactof environmental factors on the developing human gut microbiome. The authors report a longitudinal study of the gut microbiome based on DNA sequence analysis of monthly stool samples and clinical information from 39 children, about half of whom received multiple courses of antibiotics during the first 3 years of life. Whereas the gut microbiome of most children born by vaginal delivery was dominated by Bacteroides species, the four children born by cesarean section and about 20% of vaginally born children lacked Bacteroides in the first 6 to 18 months of life.
Longitudinal sampling, coupled with whole-genome shotgun sequencing, allowed detection of strain-level variation as well as the abundance of antibiotic resistance genes. The microbiota of antibiotic-treated children was less diverse in terms of both bacterial species and strains, with some species often dominated by single strains. In addition, M. Yassour et al. observed short-term composition changes between consecutive samples from children treated with antibiotics. Antibiotic resistance genes carried on microbial chromosomes showed a peak in abundance after antibiotic treatment followed by a sharp decline, whereas some genes carried on mobile elements persisted longer after antibiotic therapy ended. Those results highlight the value of high-density longitudinal sampling studies with high-resolution strain profiling for studying the establishment and response to perturbation of the infant gut microbiome.

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Intestinal microbiota restoration

Since their discovery, millions of doses of antibiotics have been used in the world both in children and adults. Antibiotic Associated gastrointestinal symptoms, mainly Diarrhea (AAD), are well-described clinical conditions associated with antibiotic use. 

New hopes for obesity and type 2 diabetes

Obesity and type 2 diabetes are important health problems worldwide. Recent evidence indicates that the gut microbiota plays a key role in the pathophysiology of obesity and type 2 diabetes. Both are characterized by low-grade inflammation, gut barrier disruption and specific changes in the gut microbiota composition.

Quality Control

Probiotics are generally defined as follows: “Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit to the host”.
There are some criteria for the definition of probiotics, including being present in a sufficient number by the end of the shelf-life, resisting to acid and bile, colonizing the gut, or having clinical trials which show the clinical benefits on specific conditions.

A new “Throw a Curve” study

The composition of intestinal microbiota is influenced by various factors and delivery mode is a well-defined one. Previous studies have shown a lower diversity and lower abundance of intestinal microbiota composition during early life in infants born by cesarean section. Dominguez-Bello and colleagues [1] showed Lactobacillus, Prevotella and Sneathia species are dominant in the intestinal microbiota of infants delivered vaginally while Staphylococcus species have been identified as the main gut microbiota in infants born by cesarean section.

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Report from the conference

THE GUT SUMMIT 2017

Paris

A workshop has allowed summarizing recent developments on the physiological bases and clinical perspectives related to the gut microbiota-brain interactions. 

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