High engraftment capacity of frozen ready-to-use human fecal microbiota transplants assessed in germ-free mice.

The number of indications for fecal microbiota transplantation is expected to rise, thus increasing the needs for production of readily available frozen or freeze-dried transplants. Using shotgun metagenomics, we investigated the capacity of two novel human fecal microbiota transplants prepared in maltodextrin-trehalose solutions (abbreviated MD and TR for maltodextrin:trehalose, 3:1, w/w, and trehalose:maltodextrin 3:1, w/w, respectively), to colonize a germ-free born mouse model. Gavage with frozen-thawed MD or TR suspensions gave the taxonomic profiles of mouse feces that best resembled those obtained with the fresh inoculum (Spearman correlations based on relative abundances of metagenomic species around 0.80 and 0.75 for MD and TR respectively), while engraftment capacity of defrosted NaCl transplants most diverged (Spearman correlations around 0.63). Engraftment of members of the family Lachnospiraceae and Ruminoccocaceae was the most challenging in all groups of mice, being improved with MD and TR transplants compared to NaCl, but still lower than with the fresh preparation. Improvement of engraftment of this important group in maintaining health represents a challenge that could benefit from further research on fecal microbiota transplant manufacturing.

Alternative stable states in the intestinal ecosystem: proof of concept in a rat model and a perspective of therapeutic implications.

BACKGROUND: Chronic immune-mediated diseases are rapidly expanding and notoriously difficult to cure. Altered relatively stable intestinal microbiota configurations are associated with several of these diseases, and with a possible pre-disease condition (more susceptible to disease development) of the host-microbiota ecosystem. These observations are reminiscent of the behavior of an ecosystem with alternative stable states (different stable configurations that can exist under identical external conditions), and we recently postulated that health, pre-disease and disease represent such alternative states. Here, our aim was to examine if alternative stable states indeed exist in the intestinal ecosystem. RESULTS: Rats were exposed to varying concentrations of DSS in order to create a wide range of mildly inflammatory conditions, in a context of diet-induced low microbiota diversity. The consequences for the intestinal microbiota were traced by 16S rRNA gene profiling over time, and inflammation of the distal colon was evaluated at sacrifice, 45 days after the last DSS treatment. The results provide the first formal experimental proof for the existence of alternative stable states in the rat intestinal ecosystem, taking both microbiota and host inflammatory status into consideration. The alternative states are host-microbiota ecosystem states rather than independent and dissociated microbiota and host states, and inflammation can prompt stable state-transition. Based on these results, we propose a conceptual model providing new insights in the interplay between host inflammatory status and microbiota status. These new insights call for innovative therapeutic strategies to cure (pre-)disease. CONCLUSIONS: We provide proof of concept showing the existence of alternative stable states in the rat intestinal ecosystem. We further propose a model which, if validated in humans, will support innovative diagnosis, therapeutic strategy, and monitoring in the treatment of chronic inflammatory conditions. This model provides a strong rationale for the application of combinatorial therapeutic strategies, targeting host and microbiota rather than only one of the two in chronic immune-mediated diseases. Video Abstract.

Lactobacillus rhamnosus CNCMI-4317 Modulates Fiaf/Angptl4 in Intestinal Epithelial Cells and Circulating Level in Mice.

BACKGROUND AND OBJECTIVES: Identification of new targets for metabolic diseases treatment or prevention is required. In this context, FIAF/ANGPTL4 appears as a crucial regulator of energy homeostasis. Lactobacilli are often considered to display beneficial effect for their hosts, acting on different regulatory pathways. The aim of the present work was to study the effect of several lactobacilli strains on Fiaf gene expression in human intestinal epithelial cells (IECs) and on mice tissues to decipher the underlying mechanisms. SUBJECTS AND METHODS: Nineteen lactobacilli strains have been tested on HT-29 human intestinal epithelial cells for their ability to regulate Fiaf gene expression by RT-qPCR. In order to determine regulated pathways, we analysed the whole genome transcriptome of IECs. We then validated in vivo bacterial effects using C57BL/6 mono-colonized mice fed with normal chow. RESULTS: We identified one strain (Lactobacillus rhamnosus CNCMI-4317) that modulated Fiaf expression in IECs. This regulation relied potentially on bacterial surface-exposed molecules and seemed to be PPAR-γ independent but PPAR-α dependent. Transcriptome functional analysis revealed that multiple pathways including cellular function and maintenance, lymphoid tissue structure and development, as well as lipid metabolism were regulated by this strain. The regulation of immune system and lipid and carbohydrate metabolism was also confirmed by overrepresentation of Gene Ontology terms analysis. In vivo, circulating FIAF protein was increased by the strain but this phenomenon was not correlated with modulation Fiaf expression in tissues (except a trend in distal small intestine). CONCLUSION: We showed that Lactobacillus rhamnosus CNCMI-4317 induced Fiaf expression in human IECs, and increased circulating FIAF protein level in mice. Moreover, this effect was accompanied by transcriptome modulation of several pathways including immune response and metabolism in vitro.

Modulation of Lactobacillus casei in ileal and fecal samples from healthy volunteers after consumption of a fermented milk containing Lactobacillus casei DN-114 001Rif.

Lactobacillus casei DN-114 001 is a probiotic strain able to interact with the immune system and to interfere with gastrointestinal pathogens. The derived strain DN-114 001Rif was studied during its transit through the upper and distal intestine of human volunteers. Seven volunteers participated in the study, which involved intestinal intubation to sample ileal contents and collection of fecal samples, with a wash-out period of 8 days between the 2 steps. The retrieval of the probiotic was analyzed in the ileum every 2 h for 8 h following the ingestion of one dose of the test product and in the feces prior to, during, and after daily consumption of the test product for 8 days. Persistence of the probiotic amplifiable DNA was assessed using temporal temperature gradient gel electrophoresis and real-time PCR. Fluorescent in situ hybridization allowed analysis of the composition of the dominant digestive microbiota. The ingestion of L. casei DN-114 001Rif led to a significant and transient increase of its amplifiable DNA in ileal and fecal samples. This is related to a high stability in the composition of dominant groups of the gut microbiota. Data from ileal samples are scarce and our study confirms the potentiality for interaction between probiotics and the human immune system.