The 2nd congress on targeting microbiota was held at Institut Pasteur in Paris on October 16-17, 2014. Professor Marvin Edeas, chairman of the scientific committee, warned the attendees about avoiding speculation where the challenge might be prevention instead of finding treatment. This should constitute a step “towards clinical revolution”.
Targeting Microbiota – Institut Pasteur
To introduce this state of the art session, Pierre-Henri Gouyon, French National Museum of Natural History, remind the audience of the basics of selection and evolution, from the individual as the unit of selection and the genes as the units of evolution. Life is not only a combination of matter but also includes information; this would correspond to the fields of physiology and genetics. He described a lot of cooperative systems which remind him of the one between a human host and its microbiota. He insisted that small competitive interactions may be beneficial to the entire ecosystem. He made the conclusion that when you study the microbiota you need to interpret the results in light of ecology and evolution. “The individual can only be understood by taking into account the ecological properties of this cell community and the evolutionary forces which drive its fates”.
Next, S. Dusko Ehrlich, INRA Metagenopolis and King’s college, talked about how gut microbial richness appears to be connected to health status. Indeed, poor individuals in terms of gut richness have a higher risk of developing metabolic syndromes such as diabetes and cardiovascular disease. He reminded the audience about the last paper from the MetaHIT consortium with the last gene catalog, with about ten million microbial genes, and the utilization of new tools to delineate genomic units in the gut microbiota; some of them correspond to bacterial species. Using six bacterial species as biomarkers, the loss of gene richness can be detected. The gene richness is connected with enterotype classification.
Nadine Cerf-Bensussan, Université Paris Descartes, gave a review about microbiota and postnatal maturation of the gut immune barrier using murine model. Indeed, this dynamic barrier fully develops only after birth in response to signals from the microbiota. She observed that human gut microbiota transplantation into mice did not impact the immune system as it did with mouse gut microbiota transplantation into mice. She discussed about the segmented filamentous bacterium which is necessary for the complete maturation of the gut immune barrier in mice. She showed how the loss of specific species can influence the fitness of the immune system, and opened the question of whether this is the case for humans.
Philippe Sansonetti, Institut Pasteur, said that this is the time to move towards “experimentomics” approaches, beyond the descriptive catalog provided by metagenomics. He showed then that a crypt specific microbiota existed in the colon and it was mainly constituted by the genus Acinetobacter in mice. As with other abundant genera in the crypt, Acinetobacter have biodegradative capabilities toward aromatic compounds and are not strictly anaerobic. Then he presented a pathway that provides stem cell protection under extreme stress conditions. This pathway involves the bacterial muramyl-dipeptide and the Nod2 sensor expressed at high levels in gut stem cells compared to Paneth cells.