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International audience; Introduction and Aims. Inflammatory Bowel Diseases (IBD), including Ulcerative Colitis (UC), coincide with alterations in the gut microbiota. Consumption of immunomodulatory strains of probiotic bacteria may induce or prolong remission in UC patients. Fermented foods, including cheeses, constitute major vectors for bacteria consumption. New evidences revealed anti-inflammatory effects of selected strains within the species P.freudenreichii, S.thermophilus and L.delbrueckii. We thus hypothesized that consumption of a functional cheese, fermented by selected strains of these three species, may exert a positive effect on IBD.Methods. Strains of each bacterial species were screened based on the ability to induce regulatory IL-10 in human immune PBMC cells, or to downregulate nuclear factor kappa B (NF-κB) activation in a cultured HT-29 human intestinal epithelial cell line. We then investigated the effect of monostrain experimental cheese. We further investigated the impact two-strains experimental cheese. Finally, we produced in industrial conditions an Emmental cheese using one selected strain of each of the three species, i.e. P. freudenreichii CIRM-BIA 129 in combination with Lactobacillus delbrueckii CNRZ327 and Streptococcus thermophilus LMD-9. Consumption of all cheeses was investigated with respect to prevention of chemically induced colitis in mice.Results. Consumption of the experimental cheeses, or of the industrial Emmental, reduced the severity of subsequent chemically induced colitis, weight loss, disease activity index and histological score, in mice. Furtherrmore, consumption of the Emmental cheese, in a preventive way, reduced small bowel Immunoglobulin A (IgA) secretion, restored occludin gene expression and prevented induction of Tumor Necrosis Factor α (TNFα), Interferon γ (IFNγ) and Interleukin-17 (IL-17).Conclusion. Assembling immunomodulatory strains of both lactic acid and propionic acid starter bacteria leads to an anti-inflammatory Emmental cheese, as revealed in vivo. This opens new perspectives for the development of functional fermented food products for personalised nutrition in the context of IBD.

Mucositis, a common and often debilitating side effect of cancer chemotherapy, is a clinically important gastrointestinal inflammatory disease. It consists in a painful inflammation and ulceration of the mucosa lining the digestive tract, which may compromise proper nutrition of the patient, as well as termination of the treatment. It thus increases mortality and morbidity and contributes to rising health care costs. Its treatment is mainly supportive and often fails to relieve symptoms. Several studies indicate a role of the microbiota and suggest a healing effect of probiotic ingestion. Probiotic bacteria may maintain homeostasis and reduce side effects of chemotherapy toxicity. A major limit to probiotic bacteria anti-inflammatory effect is their susceptibility to digestive stresses and several studies indicate the key protective role of food matrices in increasing probiotics’ effect via the protection of bacteria against digestive constraints. In this study, we investigated the role of fermented milk, using Lactobacillus casei or Propionibacterium freudenreichii as probiotic starter, and of its fortification via addition of whey proteins.Matériels et Méthodes/Materials and methodsWe evaluated the role of whey protein isolate (WPI), when added to skim milk fermented by L. casei BL23 or by P. freudenreichii 138, as a protective matrix against in vitro stress challenges. In addition, we investigated in vivo the therapeutic effect of these fermented beverages in a murine model of mucositis induced by 5-Fluorouracil (5-FU). The monitored outcomes included weight loss, ileum histopathological score, villus height, crypt depth and number of mucus-producing goblet cells.Résultats principaux/Main ResultsThis study demonstrated that milk supplementation with 30% (w/v) of WPI increases the survival rate of both strains when challenged with acid, bile salts, high temperature and cold storage stresses, compared to fermented skim milk without the addition of WPI. Moreover, treatment with the probiotic beverages prevented weight loss and intestinal damages in mice receiving 5-FU. All symptoms of mucositis were drastically reduced by the consumption of developed probiotic fermented milks.ConclusionThis study evidenced the protective effect of selected strains of both lactic and propionic acid bacteria, in the context of induced mucositis. It confirmed that selected strains might be used bot as starter and probiotic. It opens new avenues for the development of fermented functional foods for target populations.

The intestinal microbiota composition has a great impact on physiology and health, since commensal bacteria are crucial to maintain homeostasis and immune regulation of the gut. Consequently, disturbances of this microbiota, a process known as dysbiosis, have severe implications for the host health such as the rise of many gastrointestinal (GI) problems; including inflammatory disorders like the Inflammatory Bowel Diseases (IBD), mucositis, as well as colorectal cancer (CRC). The consumption of probiotics with beneficial effects is a promising tool to help treating such disorders. Indeed, they modulate diverse biological mechanisms involved in GI homeostasis and have been commonly used to reduce such disorders. In this chapter, we present the molecular mechanisms triggered by probiotic bacteria to modulate the gut physiology during gastrointestinal disorder and the importance of the gastrointestinal stresses tolerance as a limiting factors for probiotic application. Moreover, we focus on the emergence of functional probiotic foods, which can act as excellent vehicles, by enhancing stress tolerance and providing a protective matrix towards digestive stresses.