[Irritable bowel syndrome: Role of gut microbiota]. / Syndrome de l'intestin irritable - Rôle du microbiote intestinal.

Irritable Bowel Syndrome (IBS) is a functional disorder of the gastrointestinal tract with high prevalence. IBS, in particular the diarrheic subtype, is associated with alterations in gut microbiota composition and functionality, called dysbiosis. However, the treatment of this disease mainly relies on the patient's symptoms without considering the gut microbiota perturbations. In this review, we present epidemiological data about IBS-D. Then, we describe the main pathophysiological mechanisms associated with this disease, by focusing on gut microbiota alterations. We end up discussing the current therapies now available.

TITLE: Syndrome de l'intestin irritable - Rôle du microbiote intestinal. ABSTRACT: Le syndrome de l'intestin irritable (SII) est un trouble fonctionnel digestif dont la prévalence est très élevée. Ce syndrome, et notamment son sous-type diarrhéique (SII-D), est associé à des perturbations de la composition et des fonctions du microbiote intestinal à l'origine d'une dysbiose. Pourtant, la maladie est principalement traitée en fonction des symptômes des patients atteints, sans que la perturbation de leur microbiote ne soit prise en compte. Dans cette revue, nous détaillerons les données épidémiologiques de la maladie. Nous traiterons ensuite des principaux mécanismes physiopathologiques, notamment de l'impact des perturbations du microbiote intestinal. Le sous-type diarrhéique (SII-D) étant le plus fréquent [1], nous nous concentrerons principalement sur celui-ci. Nous introduirons enfin les thérapies actuelles utilisées.

Comparative methods for fecal sample storage to preserve gut microbial structure and function in an in vitro model of the human colon.

In vitro gut models, such as the mucosal artificial colon (M-ARCOL), provide timely and cost-efficient alternatives to in vivo assays allowing mechanistic studies to better understand the role of human microbiome in health and disease. Using such models inoculated with human fecal samples may require a critical step of stool storage. The effects of preservation methods on microbial structure and function in in vitro gut models have been poorly investigated. This study aimed to assess the impact of three commonly used preserving methods, compared with fresh fecal samples used as a control, on the kinetics of lumen and mucus-associated microbiota colonization in the M-ARCOL model. Feces from two healthy donors were frozen 48 h at - 80 °C with or without cryoprotectant (10% glycerol) or lyophilized with maltodextrin and trehalose prior to inoculation of four parallel bioreactors (e.g., fresh stool, raw stool stored at - 80 °C, stool stored at - 80 °C with glycerol and lyophilized stool). Microbiota composition and diversity (qPCR and 16S metabarcoding) as well as metabolic activity (gases and short chain fatty acids) were monitored throughout the fermentation process (9 days). All the preservative treatments allowed the maintaining inside the M-ARCOL of a complex and functional microbiota, but considering stabilization time of microbial profiles and activities (and not technical constraints associated with the supply of frozen material), our results highlighted 48 h freezing at - 80 °C without cryoprotectant as the most efficient method. These results will help scientists to determine the most accurate method for fecal storage prior to inoculation of in vitro gut microbiome models. KEY POINTS: • In vitro ARCOL model reproduces luminal and mucosal human microbiome. • Short-term storage of fecal sample influences microbial stabilization and activity. • 48 h freezing at - 80°C: most efficient method to preserve microbial ecosystem. • Scientific and technical requirements: influencers of preservation method.