Local treatment with lactate prevents intestinal inflammation in the TNBS-induced colitis model

Lactate has long been considered as a metabolic by-product of cells. Recently, this view has been changed by the observation that lactate can act as a signaling molecule and regulates critical functions of the immune system. We previously identified lactate as the component responsible for the modulation of innate immune epithelial response of fermented milk supernatants in vitro. We have also shown that lactate downregulates proinflammatory responses of macrophages and dendritic cells. So far, in vivo effects of lactate on intestinal inflammation have not been reported. We evaluated the effect of intrarectal administration of lactate in a murine model of colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). The increase in lactate concentration in colon promoted protective effects against TNBS-induced colitis preventing histopathological damage, as well as bacterial translocation and rise of IL-6 levels in serum. Using intestinal epithelial reporter cells, we found that flagellin treatment induced reporter gene expression, which was abrogated by lactate treatment as well as by glycolysis inhibitors. Furthermore, lactate treatment modulated glucose uptake, indicating that high levels of extracellular lactate can impair metabolic reprograming induced by proinflammatory activation. These results suggest that lactate could be a potential beneficial microbiota metabolite and may constitute an overlooked effector with modulatory properties.Centro de Investigación y Desarrollo en Criotecnología de AlimentosInstituto de Estudios Inmunológicos y Fisiopatológico

Ecotoxicology inside the gut: impact of heavy metals on the mouse microbiome

Background: The gut microbiota is critical for intestinal homeostasis. Recent studies have revealed the links between different types of dysbiosis and diseases inside and outside the intestine. Environmental exposure to pollutants (such as heavy metals) can also impair various physiological functions for good health. Here, we studied the impact of up to 8 weeks of oral lead and cadmium ingestion on the composition of the murine intestinal microbiome. Results: Pyrosequencing of 16S RNA sequences revealed minor but specific changes in bacterial commensal communities (at both family and genus levels) following oral exposure to the heavy metals, with notably low numbers of Lachnospiraceae and high numbers levels of Lactobacillaceae and Erysipelotrichaceacae (mainly due to changes in Turicibacter spp), relative to control animals. Conclusions: Non-absorbed heavy metals have a direct impact on the gut microbiota. In turn, this may impact the alimentary tract and overall gut homeostasis. Our results may enable more accurate assessment of the risk of intestinal disease associated with heavy metal ingestion

Role of the β-glucan surface polysaccharide in Propionibacterium freudenreichii: physiological and immunomodulatory properties

P. freudenreichii (PF) is a Gram + species, with the GRAS (Generally Recognized As Safe) status in the USA and a Qualified Presumption of Safety (QPS) status in Europe. It is widely consumed by humans because it is an essential ripening culture in Swiss type cheeses (Emmental, Leerdammer®…), and also as a probiotic in food supplement (Propio-Fidus®). Recently, PF was shown to produce a (1→3, 1→2)-β-D-glucan polysaccharide. A single gene (named gtf) is responsible for the biosynthesis of this surface polysaccharide, that has been immunodetected for 30% of the 100 strains of PF tested. Here we investigated the role(s) of this β-D-glucan

L’éthique au cœur du faire-équipe dans la recherche en sciences de la vie et de la santé

International audienceTeamwork is defined by multidisciplinarity : It brings together people from different socio-professional categories, backgrounds and origins, united to achieve a common goal. We question in this article the notion of “team-building” in the field of research in life sciences and health, a field that has undergone profound changes in recent years. Indeed, the decrease in recurrent financial resources, the pressures on productivity, the precariousness of employment and deadlines reducing task execution times come at a time when research institutions insist on valuing the work carried out which introduces a form of contradictory injunction. In this context, the place of each staff member within the team (responsibilities, prerogatives), their professional aspirations (commitment, recognition/visibility, projection into the future) and the quality of human interactions between them (trust, solidarity, exchanges) appear destabilized and shifting. These points can affect the very meaning of the researcher's profession. We propose an ethical vision of “teamwork” which could make it possible to rediscover the sharing of converging visions within the research team by limiting the harmful effects resulting from current organizational processes. By giving meaning to the work carried out by each member of the team, an ethical reflection on “teamwork” will allow a more harmonious mode of operation of research in the field of life sciences and health.Le travail en équipe est défini par la multidisciplinarité : il regroupe des personnes de catégories socioprofessionnelles, formations et origines différentes, réunies pour atteindre un objectif commun. Nous questionnons dans cet article la notion du « faire-équipe » dans le domaine de la recherche en sciences de la vie et de la santé, domaine ayant subi de profonds changements au cours des dernières années. En effet, la diminution des ressources financières récurrentes, les pressions à la productivité, la précarisation de l’emploi et les échéances à court terme réduisant les délais d’exécution des tâches interviennent à un moment où les institutions de recherche insistent sur la valorisation des travaux effectués ; introduisant une forme d’injonction contradictoire. Dans ce contexte, la place de chacun au sein de l’équipe (responsabilités, prérogatives), les aspirations professionnelles (engagement, reconnaissance/visibilité, projection dans l’avenir) et la qualité des interactions humaines (confiance, solidarité, échanges) apparaissent déstabilisées et mouvantes, affectant le sens même du métier de chercheur. Nous proposons une vision éthique du « faire-équipe » qui pourrait permettre de retrouver le partage de visions convergentes au sein de l’équipe de recherche en limitant les effets néfastes résultant des processus organisationnels actuels. En redonnant du sens au travail mené par chacun des membres de l’équipe, une réflexion éthique sur le « faire-équipe » suscitera un mode de fonctionnement plus harmonieux de la recherche dans le domaine des sciences de la vie et de la santé

Role of the β-glucan surface polysaccharide in Propionibacterium freudenreichii: physiological and immunomodulatory properties

P. freudenreichii (PF) is a Gram + species, with the GRAS (Generally Recognized As Safe) status in the USA and a Qualified Presumption of Safety (QPS) status in Europe. It is widely consumed by humans because it is an essential ripening culture in Swiss type cheeses (Emmental, Leerdammer®…), and also as a probiotic in food supplement (Propio-Fidus®). Recently, PF was shown to produce a (1→3, 1→2)-β-D-glucan polysaccharide. A single gene (named gtf) is responsible for the biosynthesis of this surface polysaccharide, that has been immunodetected for 30% of the 100 strains of PF tested. Here we investigated the role(s) of this β-D-glucan

Immunomodulatory properties of the β-glucan surface polysaccharide of Propionibacterium freudenreichii, a dairy bacterium with probiotic potential

P. freudenreichii (PF) is a Gram + species, with the GRAS (Generally Recognized As Safe) status in the USA and a Qualified Presumption of Safety (QPS) status in Europe. It is widely consumed by humans because it is an essential ripening culture in Swiss type cheeses (Emmental, Leerdammer®…), which contain more than 109 live cells / g of cheese. It is also used as a probiotic in food supplement (Propio-Fidus®). Recently, 30% of the strains of PF were shown shown to produce a (1→3, 1→2)-β-D-glucan surface polysaccharide. A single gene (named gtfF) is responsible for the biosynthesis. Here we investigated the role(s) of this β-glucan

Immunomodulatory properties of the β-glucan surface polysaccharide of Propionibacterium freudenreichii, a dairy bacterium with probiotic potential

P. freudenreichii (PF) is a Gram + species, with the GRAS (Generally Recognized As Safe) status in the USA and a Qualified Presumption of Safety (QPS) status in Europe. It is widely consumed by humans because it is an essential ripening culture in Swiss type cheeses (Emmental, Leerdammer®…), which contain more than 109 live cells / g of cheese. It is also used as a probiotic in food supplement (Propio-Fidus®). Recently, 30% of the strains of PF were shown shown to produce a (1→3, 1→2)-β-D-glucan surface polysaccharide. A single gene (named gtfF) is responsible for the biosynthesis. Here we investigated the role(s) of this β-glucan