Immunomodulatory properties of 10 dairy propionibacteria, analyzed on human peripheral blood mononuclear cells (PBMCs), revealed a highly strain-dependent induction of anti-inflammatory cytokine ...interleukin 10 (IL-10). Two selected strains of Propionibacterium freudenreichii showed a protective effect against two models of colitis in mice, suggesting a probiotic potential predicted by immune-based selection criteria for these cheese starter bacteria.
Dairy propionibacteria (PAB) are used as a ripening starter in combination with Lactic acid bacteria (LAB) for dairy products such as Swiss-type cheese. LAB and PAB have also been studied for their ...probiotic properties but little is still known about their individual and/or synergistic beneficial effects within dairy matrices. In the context of a rising incidence of Inflammatory Bowel Diseases, it has become crucial to evaluate the immunomodulatory potential of bacteria ingested in large numbers via dairy products. We therefore selected different strains and combinations of technological LAB and PAB. We determined their immunomodulatory potential by IL-10 and IL-12 induction, in human peripheral blood mononuclear cells, on either single or mixed cultures, grown on laboratory medium or directly in milk. Milk was fermented with selected anti-inflammatory strains of LAB or PAB/LAB mixed cultures and the resulting bacterial fractions were also evaluated for these properties, together with starter viability and optimum technological aspects. The most promising fermented milks were evaluated in the context of TNBS- or DSS-induced colitis in mice. The improvement in inflammatory parameters evidenced an alleviation of colitis symptoms as a result of fermented milk consumption. This effect was clearly strain-dependent and modulated by growth within a fermented dairy product. These findings offer new tools and perspectives for the development of immunomodulatory fermented dairy products for targeted populations.
•Dairy starters display different immunoproperties according to the growth medium.•Evaluation of immunomodulatory properties of multi-species cultures is possible.•We studied the immunomodulatory properties of the bacteria present in a fermented milk.•Propionibacterium freudenreichii is anti-inflammatory, whatever the growth medium.•Colitis symptoms were reduced as a result of fermented milk consumption.
•We model chronic ingestion of environmental lead and cadmium in axenic mice.•We addressed the role of the microbiota in heavy-metal dissemination in organs.•We delineate the direct impact of the ...non-absorbed heavy metals on gut homeostasis.•We measure transport- and oxidative-gene expression in intestine.•It enlightens risk assessment of heavy metals in intestinal disease's susceptibility.
Environmental exposure to pollutants such as heavy metal(s) is responsible for various altered physiological functions which are detrimental for health. The gut microbiota is critical for intestinal homeostasis but its role on xenobiotic handling is not fully understood, especially when continuous sub-chronic exposure is addressed. We first confirmed the essential role of the intestinal microbiome to limit heavy metal body burden by using germ-free mice following 6-weeks oral exposure. Significant increases of cadmium and lead absorption and dissemination in blood and target organs were measured in germ-free mice when compared with conventional specific pathogen free (SPF) mice. Besides the “barrier” function of the luminal microbiota, this may involve specific host-genes such as metallothioneins, which are differentially expressed in the gastrointestinal tract of each group of mice. Considering genes relevant for divalent metal transporters and oxidative pathways, significant differences in basal gene expression were measured between control and germ-free mice. Moreover, the magnitude of induction of these genes upon stimulation by heavy metals varied greatly depending on the dose and type of metal as well as the microbial status of the animal. Collectively, these data illustrate the complex host-microbes interplay occurring with environmental pollutants inside the gut.
•Ripened cheese strains elicit distinct immune responses in vitro.•Selected microbial consortia can induce opposite immune responses in vitro.•Some cocktails of cheese-strains can exacerbate ...experimental colitis in mice.•Designed cheeses may partly predict inflammatory response in vivo.•Key role of cheese's immune profile for risk assessment in IBD patients.
Although large numbers of viable microorganisms are ingested in ripened cheese, little is known about the microbial ecosystems' influence on the host's immune responses. We designed experimental smear-ripened cheeses with bacteria and yeasts that have opposite immune effects and evaluated their impact in the dextran sulphate sodium (DSS) and trinitrobenzene sulphonic acid (TNBS) colitis mouse models. Mice were fed with a control diet, a milk matrix or with lab-designed, 28-day-ripened prototype soft cheeses A and B (CheA and CheB) from cow milk that respectively hosted consortia of immuno-enhancing and immuno-modulatory microbial strains. Inflammatory markers and transcriptional signatures were evaluated in healthy mice colitic mice. In the DSS colitis model, there were no differences between CheA and CheB in terms of the inflammatory read-outs. In contrast, CheA (but not CheB) exacerbated weight loss and colon lesions in the TNBS model suggesting that designer cheeses may provide opportunities for diet management.
Chronic ingestion of environmental heavy metals such as lead (Pb) and cadmium (Cd) causes various well-documented pathologies in specific target organs following their intestinal absorption and ...subsequent accumulation. However, little is known about the direct impact of the non-absorbed heavy metals on the small intestine and the colon homeostasis. The aim of our study was to compare the specific bioaccumulation and retention of Cd and Pb and their effect on the essential metal balance in primary organs, with those occurring specifically in the gastrointestinal tract of mice. Various doses of Cd (5, 20 and 100 mg l
−1
) and Pb (100 and 500 mg l
−1
) chloride salts were provided in drinking water for subchronic to chronic exposures (4, 8 and 12 weeks). In contrast to a clear dose- and time-dependent accumulation in target organs, results showed that intestines are poor accumulators for Cd and Pb. Notwithstanding, changes in gene expression of representative intestinal markers revealed that the transport-, oxidative- and inflammatory status of the gut epithelium of the duodenum, ileum and colon were specifically affected by both heavy metal species. Additionally, in vivo comet assay used to evaluate the impact of heavy metals on DNA damage showed clear genotoxic activities of Cd, on both the upper and distal parts of the gastrointestinal tract. Altogether, these results outline the resilience of the gut which balances the various effects of chronic Cd and Pb in the intestinal mucosa. Collectively, it provides useful information for the risk assessment of heavy metals in gut homeostasis and further disease’s susceptibility.
The widely used probiotic bacteria belong to the genera
Lactobacillus and
Bifidobacterium and have in most cases been isolated from the human gastrointestinal tract. However, other “less ...conventional” bacteria, from allochthonous or extremophilic origin, sharing similar structural or functional features, may also confer specific health benefits to a host. Firstly, we explored the
in vitro immuno-modulatory or immune-stimulatory activities of 25 wine lactic acid bacteria belonging to
Oenococcus oeni and
Pediococcus parvulus. While cytokines released by peripheral blood mononuclear cells (PBMCs) stimulated by
P. parvulus strains, showed little variation,
O. oeni strains induced strain-specific cytokine patterns. Some
O. oeni strains were then further analyzed under various conditions for growth, dose and culture medium. In a second phase, we evaluated the oral tolerance and safety of two strains of
O. oeni in mice fed a high dose of bacteria for a week. Finally, evidence was gathered on the
in vivo anti-inflammatory potential of a selected
O. oeni strain using an experimental 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis mouse model. Although results did not match the anti-inflammatory levels obtained with certain conventional probiotics, strain IOEB 9115 significantly lowered colonic injury and alleviated colitis symptoms. The ‘natural’ tolerance towards acid, ethanol, and phenolic compounds of
O. oeni strains combined with a measureable immunomodulatory potential, suggest a possible use of selected strains isolated from wine as live probiotics.
Disruption of the intestinal homeostasis and tolerance towards the resident microbiota is a major mechanism involved in the development of inflammatory bowel disease. While some bacteria are inducers ...of disease, others, known as probiotics, are able to reduce inflammation. Because dendritic cells (DCs) play a central role in regulating immune responses and in inducing tolerance, we investigated their role in the anti-inflammatory potential of probiotic lactic acid bacteria.
Selected LAB strains, while efficiently taken up by DCs in vitro, induced a partial maturation of the cells. Transfer of probiotic-treated DCs conferred protection against 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Protection was associated with a reduction of inflammatory scores and colonic expression of pro-inflammatory genes, while a high local expression of the immunoregulatory enzyme indolamine 2, 3 dioxgenase (IDO) was observed. The preventive effect of probiotic-pulsed DCs required not only MyD88-, TLR2- and NOD2-dependent signaling but also the induction of CD4+ CD25+ regulatory cells in an IL-10-independent pathway.
Altogether, these results suggest that selected probiotics can stimulate DC regulatory functions by targeting specific pattern-recognition receptors and pathways. The results not only emphasize the role of DCs in probiotic immune interactions, but indicate a possible role in immune-intervention therapy for IBD.
Thirty-six microorganisms (twenty-one bacteria, twelve yeasts and three fungi) were isolated from surface-ripened cheeses and subjected to in vitro digestive stress. The approach mimicked gastric ...and/or duodenal digestion. Lactobacillus rhamnosus GG, Escherichia coli Nissle 1917 and Saccharomyces boulardii were used as reference strains. We studied the microorganisms grown separately in culture medium and then included (or not) in a rennet gel. The microorganisms' immunomodulatory abilities were also assessed by profiling cytokine induction in human peripheral blood mononuclear cells (PBMCs). The loss of viability was less than 1logCFU/mL for yeasts under all conditions. In contrast, Gram-negative bacteria survived gastric and/or duodenal stress well but most of the Gram-positive bacteria were more sensitive (especially to gastric stress). Inclusion of sensitive Gram-positive bacteria in rennet gel dramatically improved gastric survival, when compared with a non-included cultured (with a 4logCFU/mL change in survival). However, the rennet gel did not protect the bacteria against duodenal stress. The PBMC cytokine assay tests showed that the response to yeasts was usually anti-inflammatory, whereas the response to bacteria varied from one strain to another.
•We performed a two-step, in vitro batch digestive stress experiment.•We tested the immunomodulatory properties of microorganisms isolated from cheeses.•Gram-positive and Gram-negative bacteria differed in their resistance to digestive challenge.•All yeast species had very similar immunomodulatory profiles.•Rennet gel inclusion protected bacteria against gastric challenge.
AIM: To evaluate the in vitro immunomodulation capacity of various non-pathogenic yeast strains and to investigate the ability of some of these food grade yeasts to prevent experimental colitis in ...mice.METHODS: In vitro immunomodulation was assessed by measuring cytokines interleukin (IL)-12p70,IL-10,tumor necrosis factor and interferon γ released by human peripheral blood mononuclear cells after 24 h stimulation with 6 live yeast strains (Saccharomyces ssp.) and with bacterial reference strains.A murine ...
PDF
