Recommendations for improved use of the murine TNBS-induced colitis model in evaluating anti-inflammatory properties of lactic acid bacteria: technical and microbiological aspects

Koumiss and immunity: A thorough investigation of fermentation parameters and their impact on health benefits

The aim of this study was to determine the components and cytokine and immunoglobulin levels of koumiss during different fermentation periods, and to reveal the interrelation between these parameters. For achieving this objective, 10 samples of koumiss were prepared and randomly divided into 2 groups: the first group was sampled at 0, 1, 5, 12, and 24 h of incubation at room temperature for analysis. The second group was stored at +4°C, and samples were taken on d 5, 10, 15, and 20. The counts of Enterobacteriaceae spp., Staphylococcus, and Micrococcus spp. progressively decreased with the period of fermentation until becoming undetectable in the final samples of both groups. We fond positive or negative correlations between cytokine and immunoglobulin levels and the physicochemical and microbiological parameters in the koumiss samples in both groups. However, the levels of IFN-γ, IL-2, TNF-α, and IgG did not change significantly over time in both groups. Overall, it is clear that traditionally prepared koumiss under different fermentation times and temperatures does not show any differences in cytokine and immunoglobulin concentrations.

The Role of Genetically Engineered Probiotics for Treatment of Inflammatory Bowel Disease: A Systematic Review

BACKGROUND

Many preclinical studies have demonstrated the effectiveness of genetically modified probiotics (gm probiotics) in animal models of inflammatory bowel disease (IBD).

OBJECTIVE

This systematic review was performed to investigate the role of gm probiotics in treating IBD and to clarify the involved mechanisms.

METHODS

PubMed, Web of Science, Cochrane Library, and Medline were searched from their inception to 18 September 2022 to identify preclinical and clinical studies exploring the efficacy of gm probiotics in IBD animal models or IBD patients. Two independent researchers extracted data from the included studies, and the data were pooled by the type of study; that is, preclinical or clinical.

RESULTS

Forty-five preclinical studies were included. In these studies, sodium dextran sulfate and trinitrobenzene sulfonic acid were used to induce colitis. Eleven probiotic species have been genetically modified to produce therapeutic substances, including IL-10, antimicrobial peptides, antioxidant enzymes, and short-chain fatty acids, with potential therapeutic properties against colitis. The results showed generally positive effects of gm probiotics in reducing disease activity and ameliorating intestinal damage in IBD models; however, the efficacy of gm probiotics compared to that of wild-type probiotics in many studies was unclear. The main mechanisms identified include modulation of the diversity and composition of the gut microbiota, production of regulatory metabolites by beneficial bacteria, reduction of the pro- to anti-inflammatory cytokine ratio in colonic tissue and plasma, modulation of oxidative stress activity in the colon, and improvement of intestinal barrier integrity. Moreover, only one clinical trial with 10 patients with Crohn's disease was included, which showed that L. lactis producing IL-10 was safe, and a decrease in disease activity was observed in these patients.

CONCLUSIONS

Gm probiotics have a certain efficacy in colitis models through several mechanisms. However, given the scarcity of clinical trials, it is important for researchers to pay more attention to gm probiotics that are more effective and safer than wild-type probiotics to facilitate further clinical translation.

Could IL-25 be a potential therapeutic target for intestinal inflammatory diseases?

As a member of the IL-17 cytokine family, IL-25 (also called IL-17E) induces and sustains type 2 immunity. IL-25, which is mainly produced by intestinal epithelial cells, has been gradually investigated in recent years for its function in intestinal inflammation but is not yet fully understood. This review summarizes the expression and function of IL-25 in the intestine, especially the progression of its regulatory role on type 2 immunity-related cells. Finally, we discuss the dual role of IL-25 based on inflammatory bowel disease to inform research on targeting IL-25 for the treatment of intestinal inflammatory diseases.

Persistence and dynamics of fluorescent Lactobacillus plantarum in the healthy versus inflamed gut

The gastrointestinal tract is the main ecological niche in which Lactobacillus strains may provide health benefits in mammals. There is currently a need to characterize host-microbe interactions in space and time by tracking these bacteria in vivo. We combined noninvasive whole-body imaging with ex vivo fluorescence confocal microscopy imaging to monitor the impact of intestinal inflammation on the persistence of orally administered Lactobacillus plantarum NCIMB8826 in healthy and inflamed mouse colons. We developed fluorescent L. plantarum strains and demonstrated that mCherry is the best system for in vivo imaging and ex vivo fluorescence confocal microscopy of these bacteria. We also used whole-body imaging to show that this anti-inflammatory, orally administered strain persists for longer and at higher counts in the inflamed colon than in the healthy colon. We confirmed these results by the ex vivo confocal imaging of colons from mice with experimental colitis for 3 days after induction. Moreover, extended orthogonal view projections enabled us to localize individual L. plantarum in sites that differed for healthy versus inflamed guts. In healthy colons, orally administered bacteria were localized in the lumen (in close contact with commensal bacteria) and sometimes in the crypts (albeit very rarely in contact with intestinal cells). The bacteria were observed within and outside the mucus layer. In contrast, L. plantarum bacteria in the inflamed colon were mostly located in the lumen and (in less inflamed areas) within the mucus layer. In more intensely inflamed areas (i.e., where the colon had undergone structural damage), the L. plantarum were in direct contact with damaged epithelial cells. Taken as a whole, our results show that fluorescently labeled L. plantarum can be used to study the persistence of these bacteria in inflamed guts using both noninvasive whole-body imaging and ex vivo fluorescence confocal microscopy.

In Vitro Characterization of Gut Microbiota-Derived Commensal Strains: Selection of Parabacteroides distasonis Strains Alleviating TNBS-Induced Colitis in Mice

Alterations in the gut microbiota composition and diversity seem to play a role in the development of chronic diseases, including inflammatory bowel disease (IBD), leading to gut barrier disruption and induction of proinflammatory immune responses. This opens the door for the use of novel health-promoting bacteria. We selected five Parabacteroides distasonis strains isolated from human adult and neonates gut microbiota. We evaluated in vitro their immunomodulation capacities and their ability to reinforce the gut barrier and characterized in vivo their protective effects in an acute murine model of colitis. The in vitro beneficial activities were highly strain dependent: two strains exhibited a potent anti-inflammatory potential and restored the gut barrier while a third strain reinstated the epithelial barrier. While their survival to in vitro gastric conditions was variable, the levels of P. distasonis DNA were higher in the stools of bacteria-treated animals. The strains that were positively scored in vitro displayed a strong ability to rescue mice from colitis. We further showed that two strains primed dendritic cells to induce regulatory T lymphocytes from naïve CD4⁺ T cells. This study provides better insights on the functionality of commensal bacteria and crucial clues to design live biotherapeutics able to target inflammatory chronic diseases such as IBD.

Synbiotic Matchmaking in Lactobacillus plantarum: Substrate Screening and Gene-Trait Matching To Characterize Strain-Specific Carbohydrate Utilization

Synbiotics are food supplements that combine probiotics and prebiotics to synergistically elicit a health effect in humans. Lactobacillus plantarum exhibits remarkable genetic and phenotypic diversity, in particular in strain-specific carbohydrate utilization capacities, and several strains are marketed as probiotics. We have screened 77 L. plantarum strains for their abilities to utilize specific prebiotic fibers, revealing variable and strain-specific growth efficiencies on isomalto- and galactooligosaccharides. We identified a single strain within the screening panel that was able to effectively utilize inulin and fructooligosaccharides (FOS), which did not support efficient growth of the rest of the strains. In the panel we tested, we did not find strains that could utilize arabinoxylooligosaccharides or sulfated fucoidan. The strain-specific growth phenotype on isomaltooligosaccharides was further analyzed using high-performance anion-exchange chromatography, which revealed distinct substrate utilization phenotypes within the strain panel. The strain-specific phenotypes could be linked to the strains' genotypes by identifying gene clusters coding for carbohydrate membrane transport systems that are predicted to be involved in the utilization of isomaltose and other (unidentified) oligosaccharides in the isomaltooligosaccharide substrate.IMPORTANCE Synbiotics combine prebiotics and probiotics to synergistically enhance the health benefits associated with these ingredients. Lactobacillus plantarum is encountered as a natural inhabitant of the gastrointestinal tract, and specific strains are marketed as probiotics based on their strain-specific health-promoting activities. Strain-specific stimulation of growth through prebiotic substrates could enhance the persistence and/or activity of L. plantarum in situ Our study establishes a high-throughput screening model for prebiotic substrate utilization by individual strains of bacteria, which can be readily employed for synbiotic matchmaking approaches that aim to enhance the intestinal delivery of probiotics through strain-specific, selective growth stimulation.

Faecalibacterium prausnitzii produces butyrate to decrease c-Myc-related metabolism and Th17 differentiation by inhibiting histone deacetylase 3

Decreased levels of Faecalibacterium prausnitzii (F. prausnitzii), whose supernatant plays an anti-inflammatory effect, are frequently found in inflammatory bowel disease (IBD) patients. However, the anti-inflammatory products in F. prausnitzii supernatant and the mechanism have not been fully investigated. Here we found that F. prausnitzii and F. prausnitzii-derived butyrate were decreased in the intestines of IBD patients. Supplementation with F. prausnitzii supernatant and butyrate could ameliorate colitis in an animal model. Butyrate, but not other substances produced by F. prausnitzii, exerted an anti-inflammatory effect by inhibiting the differentiation of T helper 17 (Th17) cells. The mechanism underlying the anti-inflammatory effects of the butyrate produced by F. prausnitzii involved the enhancement of the acetylation-promoted degradation of c-Myc through histone deacetylase 3 (HDAC3) inhibition. In conclusion, F. prausnitzii produced butyrate to decrease Th17 differentiation and attenuate colitis through inhibiting HDAC3 and c-Myc-related metabolism in T cells. The use of F. prausnitzii may be an effective new approach to decrease the level of Th17 cells in the treatment of inflammatory diseases.

Lactobacillus reuteri 5454 and Bifidobacterium animalis ssp. lactis 5764 improve colitis while differentially impacting dendritic cells maturation and antimicrobial responses

Crohn’s disease is linked to a decreased diversity in gut microbiota composition as a potential consequence of an impaired anti-microbial response and an altered polarization of T helper cells. Here, we evaluated the immunomodulatory properties of two potential probiotic strains, namely a Bifidobacterium animalis spp. lactis Bl 5764 and a Lactobacillus reuteri Lr 5454 strains. Both strains improved colitis triggered by either 2,4,6-trinitrobenzenesulfonic acid (TNBS) or Citrobacter rodentium infection in mice. Training of dendritic cells (DC) with Lr 5454 efficiently triggered IL-22 secretion and regulatory T cells induction in vitro, while IL-17A production by CD4⁺ T lymphocytes was stronger when cultured with DCs that were primed with Bl 5764. This strain was sufficient for significantly inducing expression of antimicrobial peptides in vivo through the Crohn’s disease predisposing gene encoding for the nucleotide-binding oligomerization domain, containing protein 2 (NOD2). In contrast, NOD2 was dispensable for the impact on antimicrobial peptide expression in mice that were monocolonized with Lr 5454. In conclusion, our work highlights a differential mode of action of two potential probiotic strains that protect mice against colitis, providing the rational for a personalized supportive preventive therapy by probiotics for individuals that are genetically predisposed to Crohn’s disease.

Beneficial Propionibacteria within a Probiotic Emmental Cheese: Impact on Dextran Sodium Sulphate-Induced Colitis in Mice

BACKGROUNDS 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 in selected strains of Propionibacterium freudenreichii. We thus hypothesized that consumption of a functional cheese, fermented by such a strain, may exert a positive effect on IBD.

METHODS

We investigated the impact of cheese fermented by P. freudenreichii on gut inflammation. We developed an experimental single-strain cheese solely fermented by a selected immunomodulatory strain of P. freudenreichii, CIRM-BIA 129. We moreover produced, in industrial conditions, an Emmental cheese using the same strain, in combination with Lactobacillus delbrueckii CNRZ327 and Streptococcus thermophilus LMD-9, as starters. Consumption of both cheeses was investigated with respect to prevention of Dextran Sodium Sulphate (DSS)-induced colitis in mice.

RESULTS

Consumption of the single-strain experimental cheese, or of the industrial Emmental, both fermented by P. freudenreichii CIRM-BIA 129, reduced severity of subsequent DSS-induced colitis, weight loss, disease activity index and histological score. Both treatments, 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).

CONCLUSIONS

A combination of immunomodulatory strains of starter bacteria can be used to manufacture an anti-inflammatory cheese, as revealed in an animal model of colitis. This opens new perspectives for personalised nutrition in the context of IBD.

Human β-Defensin 2 Mediated Immune Modulation as Treatment for Experimental Colitis

Defensins represents an integral part of the innate immune system serving to ward off potential pathogens and to protect the intestinal barrier from microbial encroachment. In addition to their antimicrobial activities, defensins in general, and human β-defensin 2 (hBD2) in particular, also exhibit immunomodulatory capabilities. In this report, we assessed the therapeutic efficacy of systemically administered recombinant hBD2 to ameliorate intestinal inflammation in three distinct animal models of inflammatory bowel disease; i.e., chemically induced mucosal injury (DSS), loss of mucosal tolerance (TNBS), and T-cell transfer into immunodeficient recipient mice. Treatment efficacy was confirmed in all tested models, where systemically administered hBD2 mitigated inflammation, improved disease activity index, and hindered colitis-induced body weight loss on par with anti-TNF-α and steroids. Treatment of lipopolysaccharide (LPS)-activated human peripheral blood mononuclear cells with rhBD2 confirmed the immunomodulatory capacity in the circulatory compartment. Subsequent analyzes revealed dendritic cells (DCs) as the main target population. Suppression of LPS-induced inflammation was dependent on chemokine receptor 2 (CCR2) expression. Mechanistically, hBD2 engaged with CCR2 on its DC target cell to decrease NF-κB, and increase CREB phosphorylation, hence curbing inflammation. To our knowledge, this is the first study showing in vivo efficacy of a systemically administered defensin in experimental disease.

Bacteriocin biosynthesis contributes to the anti-inflammatory capacities of probiotic Lactobacillus plantarum

Plantaricin EF (PlnEF) is a class IIb bacteriocin produced by Lactobacillus plantarum. We compared L. plantarum NCIMB8826 and LM0419, a plnEFI deletion mutant of that strain lacking plnEF and the gene for the cognate immunity protein plnI, in a 2,4,6-trinitrobenzenesulfonic acid (TNBS) induced mouse model of acute inflammatory bowel disease. Mice fed either L. plantarum NCIMB8826 or LM0419 were not protected against TNBS according to either disease activity or histology (Ameho) scores. Mice consuming NCIMB8826 exhibited intermediate (non-significant) levels of colonic tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) that ranged between the TNBS-treated animals and healthy controls. By comparison, TNF-α and IL-6 quantities were elevated in mice given L. plantarum LM0419 and equivalent to mice given TNBS alone. Both strains survived digestive tract transit in equal numbers and did not result in global changes to the bacterial composition in the intestine according to 16S rRNA gene sequencing either prior to or after TNBS administration. Examination of intestinal taxa showed that mice consuming wild-type L. plantarum, but not LM0419 contained lower proportions of Mucispirillum (Deferribacteres phylum) in the faeces prior to TNBS administration and Parabacteroides (Bacteroidetes phylum) in the caecum after disease induction. Parabacteroides also positively correlated with disease activity and histology scores. These findings suggest a role for PlnEFI production by L. plantarum in benefiting digestive tract health.

Spray-drying process preserves the protective capacity of a breast milk-derived Bifidobacterium lactis strain on acute and chronic colitis in mice

Gut microbiota dysbiosis plays a central role in the development and perpetuation of chronic inflammation in inflammatory bowel disease (IBD) and therefore is key target for interventions with high quality and functional probiotics. The local production of stable probiotic formulations at limited cost is considered an advantage as it reduces transportation cost and time, thereby increasing the effective period at the consumer side. In the present study, we compared the anti-inflammatory capacities of the Bifidobacterium animalis subsp. lactis (B. lactis) INL1, a probiotic strain isolated in Argentina from human breast milk, with the commercial strain B. animalis subsp. lactis BB12. The impact of spray-drying, a low-cost alternative of bacterial dehydration, on the functionality of both bifidobacteria was also investigated. We showed for both bacteria that the spray-drying process did not impact on bacterial survival nor on their protective capacities against acute and chronic colitis in mice, opening future perspectives for the use of strain INL1 in populations with IBD.

A lactic acid bacterium isolated from kimchi ameliorates intestinal inflammation in DSS-induced colitis

Some species of lactic acid bacteria have been shown to be beneficial in inflammatory bowel disease (IBD). In the present study, a strain of lactic acid bacterium (Lactobacillus paracasei LS2) was isolated from the Korean food, kimchi, and was shown to inhibit the development of experimental colitis induced by dextran sulfate sodium (DSS). To investigate the role of LS2 in IBD, mice were fed DSS in drinking water for seven days along with LS2 bacteria which were administered intragastrically to some of the mice, while phosphate-buffered saline (PBS) was administered to others (the controls). The administration of LS2 reduced body weight loss and increased survival, and disease activity indexes (DAI) and histological scores indicated that the severity of colitis was significantly reduced. The production of inflammatory cytokines and myeloperoxidase (MPO) activity also decreased. Flow cytometry analysis showed that the number of Th1 (IFN-γ) population cells was significantly reduced in the LS2-administered mice compared with the controls. The administration of LS2 induced the increase of CD4⁺FOXP3⁺ Treg cells, which are responsible for IL-10. Numbers of macrophages (CD11b⁺ F4/80⁺), and neutrophils (CD11b⁺ Gr-1⁺) among lamina propria lymphocytes (LPL) were also reduced. These results indicate that LS2 has an anti-inflammatory effect and ameliorates DSS-induced colitis.

Butyrate inhibits interleukin-17 and generates Tregs to ameliorate colorectal colitis in rats

Background

Butyrate is an energy source for colonocytes that is formed by bacterial fermentation of dietary fiber in the colon and that exerts broad anti-inflammatory activities. Although the administration of butyrate improves homeostasis in patients and ameliorates IBD (Inflammatory Bowel Disease)-related lesions and symptoms, the anti-inflammatory mechanisms of butyrate still remain unclear. To explore the impact of butyrate on Treg (Regulatory T cell)/Th17 (T helper 17 cell) differentiation and colitis in rats.

Methods

The effect of butyrate on the expression of markers related to both Tregs and Th17 cells were determined in human monocytes as well as a rat model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid. Rats were treated with butyrate in vivo, whereas the rat splenocytes and human monocytes were treated in vitro.

Results

We found that butyrate administration increased peripheral blood Treg cell levels as well as plasma levels of anti-Th17 cytokines (IL-10 and IL-12). Butyrate administration further suppressed IL-17 levels in both plasma and colonic mucosa, and ameliorated colonic colitis lesions in rats. This promotion of Treg activity and inhibition of IL-17 release was also observed in human venous monocytes and rat splenocytes in vitro.

Conclusions

Our results suggest that butyrate plays a key role in regulating the Treg/Th17 balance and ultimately protects the colon mucosa against the development of IBD.

Lactobacillus plantarum WCFS1 and its host interaction: a dozen years after the genome

Lactobacillus plantarum WCFS1 is one of the best studied Lactobacilli, notably as its genome was unravelled over 12 years ago. L. plantarum WCFS1 can be grown to high densities, is amenable to genetic transformation and highly robust with a relatively high survival rate during the gastrointestinal passage. In this review, we present and discuss the main insights provided by the functional genomics research on L. plantarum WCFS1 with specific attention for the molecular mechanisms related to its interaction with the human host and its potential to modify the immune system, and induce other health-related benefits. Whereas most insight has been gained in mouse and other model studies, only five human studies have been reported with L. plantarum WCFS1. Hence NCIMB 8826 (the parental strain of L. plantarum WCFS1) in human trials as to capitalize on the wealth of knowledge that is summarized here.

FolC2-mediated folate metabolism contributes to suppression of inflammation by probiotic Lactobacillus reuteri

Bacterial‐derived compounds from the intestinal microbiome modulate host mucosal immunity. Identification and mechanistic studies of these compounds provide insights into host–microbial mutualism. Specific Lactobacillus reuteri strains suppress production of the proinflammatory cytokine, tumor necrosis factor (TNF), and are protective in a mouse model of colitis. Human‐derived L. reuteri strain ATCC PTA 6475 suppresses intestinal inflammation and produces 5,10‐methenyltetrahydrofolic acid polyglutamates. Insertional mutagenesis identified the bifunctional dihydrofolate synthase/folylpolyglutamate synthase type 2 (folC2) gene as essential for 5,10‐methenyltetrahydrofolic acid polyglutamate biosynthesis, as well as for suppression of TNF production by activated human monocytes, and for the anti‐inflammatory effect of L. reuteri 6475 in a trinitrobenzene sulfonic acid‐induced mouse model of acute colitis. In contrast, folC encodes the enzyme responsible for folate polyglutamylation but does not impact TNF suppression by L. reuteri. Comparative transcriptomics between wild‐type and mutant L. reuteri strains revealed additional genes involved in immunomodulation, including previously identified hdc genes involved in histidine to histamine conversion. The folC2 mutant yielded diminished hdc gene cluster expression and diminished histamine production, suggesting a link between folate and histadine/histamine metabolism. The identification of genes and gene networks regulating production of bacterial‐derived immunoregulatory molecules may lead to improved anti‐inflammatory strategies for digestive diseases.

Methods of Inducing Inflammatory Bowel Disease in Mice

Animal models of experimentally induced inflammatory bowel disease (IBD) are useful for understanding more about the mechanistic basis of the disease, identifying new targets for therapeutic intervention, and testing novel therapeutics. This unit provides detailed protocols for five widely used mouse models of experimentally induced intestinal inflammation: chemical induction of colitis by dextran sodium sulfate (DSS), hapten-induced colitis via 2,4,6-trinitrobenzene sulfonic acid (TNBS), Helicobacter-induced colitis in mdr1a(-/-) mice, the CD4(+) CD45RB(hi) SCID transfer colitis model, and the IL-10(-/-) colitis model. © 2016 by John Wiley & Sons, Inc.

Carcinoembryonic antigen related cellular adhesion molecule 1 alleviates dextran sulfate sodium-induced ulcerative colitis in mice

AIMS

To investigate the effects of exogenous carcinoembryonic antigen related cellular adhesion molecule 1 (CEACAM1) on ulcerative colitis (UC) in a dextran sulfate sodium (DSS)-induced mouse model.

MAIN METHODS

UC mice model was induced by administration of DSS in drinking water for 7days. Treatment of CEACAM1 was performed by a transrectal injection of CEACAM1 gene packed adenovirus in the mice. The severity of UC was evaluated using disease activity index and colon length. Histological changes were observed after hematoxylin and eosin staining. ELISA was used to measure secretion of pro-inflammatory cytokines in the colon tissue. The expression of mRNA and protein were detected using real-time PCR and western blotting. The effect of CEACAM1 on epithelial cell restitution was evaluated using wound-healing test in Caco-2 cells.

KEY FINDINGS

CEACAM1 overexpression attenuated the symptoms of UC as evidenced by decreased DAI score, increased colon length and histopathologic score. In addition, exogenous CEACAM1 reduced the levels of inflammatory cytokines and downregulated COX-2 and iNOS expression levels. Moreover, CEACAM1 overexpression decreased colonic permeability by upregulating expression of tight junction proteins. In the in vitro study, exogenous CEACAM1 promoted proliferation and migration of Caco-2 cell.

SIGNIFICANCE

Exogenous CEACAM1 effectively rescues the symptoms of UC in DSS mice through preventing inflammatory responses, improving epithelial barrier and promoting epithelial cells restitution.

Histamine H2 Receptor-Mediated Suppression of Intestinal Inflammation by Probiotic Lactobacillus reuteri

Probiotics and commensal intestinal microbes suppress mammalian cytokine production and intestinal inflammation in various experimental model systems. Limited information exists regarding potential mechanisms of probiotic-mediated immunomodulation in vivo. In this report, we demonstrate that specific probiotic strains of Lactobacillus reuteri suppress intestinal inflammation in a trinitrobenzene sulfonic acid (TNBS)-induced mouse colitis model. Only strains that possess the hdc gene cluster, including the histidine decarboxylase and histidine-histamine antiporter genes, can suppress colitis and mucosal cytokine (interleukin-6 [IL-6] and IL-1β in the colon) gene expression. Suppression of acute colitis in mice was documented by diminished weight loss, colonic injury, serum amyloid A (SAA) protein concentrations, and reduced uptake of [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) in the colon by positron emission tomography (PET). The ability of probiotic L. reuteri to suppress colitis depends on the presence of a bacterial histidine decarboxylase gene(s) in the intestinal microbiome, consumption of a histidine-containing diet, and signaling via the histamine H2 receptor (H2R). Collectively, luminal conversion of l-histidine to histamine by hdc⁺L. reuteri activates H2R, and H2R signaling results in suppression of acute inflammation within the mouse colon.

Probiotics are microorganisms that when administered in adequate amounts confer beneficial effects on the host. Supplementation with probiotic strains was shown to suppress intestinal inflammation in patients with inflammatory bowel disease and in rodent colitis models. However, the mechanisms of probiosis are not clear. Our current studies suggest that supplementation with hdc⁺L. reuteri, which can convert l-histidine to histamine in the gut, resulted in suppression of colonic inflammation. These findings link luminal conversion of dietary components (amino acid metabolism) by gut microbes and probiotic-mediated suppression of colonic inflammation. The effective combination of diet, gut bacteria, and host receptor-mediated signaling may result in opportunities for therapeutic microbiology and provide clues for discovery and development of next-generation probiotics.

Probiotic and anti-inflammatory attributes of an isolate Lactobacillus helveticus NS8 from Mongolian fermented koumiss

BACKGROUND

Koumiss is a traditionally fermented mare's milk described with health-promoting potentials for decades. However, only a few studies focused on the probiotic strains isolated from koumiss. In this study, we collected koumiss samples from Inner Mongolian pasturing area of China and selected a promising strain of Lactobacillus helveticus, isolate NS8, based on the survival abilities in gastrointestinal tract (GIT) and adhesion to intestinal endothelial cells in vitro. As the ability to positively modulate host immune response is a feature of increasing importance in measuring the probiotic potential of a bacterial strain, our study mainly focus on the immunomodulatory properties of L. helveticus NS8 by using in vivo and ex vivo analyses.

RESULTS

L. helveticus NS8 was identified by molecular-typing methods, both at genus and species levels. As a typical food niche-specific bacteria, NS8 showed a moderate survival ability in GIT environment in vitro. However, an excellent binding capacity to the human intestinal epithelial cells, along with significant autoaggregation and cell-surface hydrophobicity was observed. Additionally, the presence of S-layer protein was responsible for the cell surface properties of this strain. NS8 was found to be rather protective against TNBS (2,4,6-trinitrobenzene sulfonic acid)-induced murine colitis. In the meantime, co-culture with NS8 induced an increased level of secretion of anti-inflammatory cytokine IL-10 in peripheral blood mono-nuclear cells (PBMCs). Furthermore, NS8 was also able to diminish the proinflammatory effects of lipopolysaccharide (LPS) in mouse macrophage cell line RAW264.7 by inducing higher levels of IL-10. Specially, adding of the purified S-layer protein didn't influence the production of IL-10. The specific ligand-host receptor interactions on the NS8 specific immune responses need to be learned further.

CONCLUSION

In summary, L. helveticus NS8 exhibited good probiotic and particularly immunomodulatory properties, with a potential for development of functional food commercially or therapeutic adjuvant for inflammatory diseases.

The Probiotic Mixture VSL#3 Has Differential Effects on Intestinal Immune Parameters in Healthy Female BALB/c and C57BL/6 Mice

BACKGROUND

Probiotic bacteria may render mice resistant to the development of various inflammatory and infectious diseases.

OBJECTIVE

This study aimed to identify mechanisms by which probiotic bacteria may influence intestinal immune homeostasis in noninflammatory conditions.

METHODS

The effect of VSL#3, a mixture of 8 probiotic bacteria, on intestinal gene expression was studied in healthy female BALB/c and C57BL/6 mice after prolonged oral treatment (28 d, triweekly) with 3 × 10(8) colony-forming units of VSL#3. In a separate experiment in BALB/c mice, the effects of prolonged administration of VSL#3 and of phosphate-buffered saline (PBS), followed by 1 single dose of VSL#3, on innate and adaptive immune cells were evaluated.

RESULTS

Microarray analysis of the intestines of mice treated with PBS confirmed well-established differences in the expression of immune-related genes between C57BL/6 and BALB/c mice. Prolonged administration of VSL#3 was associated with downregulation of Il13 [fold change (FC) = 0.46] and Eosinophil peroxidase (Epx) (FC = 0.44) and upregulation of Il12rb1 (FC = 2.1), C-C chemokine receptor type 5 (Ccr5) (FC = 2.6), chemokine (C-X-C motif) receptor 3 (Cxcr3) (FC = 1.6), and C-X-C motif chemokine 10 (Cxcl10) (FC = 2.8) in BALB/c mice but not in C57BL/6 mice. In BALB/c mice, it was shown that 28 d of treatment with VSL#3 affected the Peyer's patches (PPs) and mesenteric lymph nodes (MLNs), which was evident from an increase in B cells (26% and 8%, respectively), a decrease in T cells (21% and 8%, respectively), and an increase in cluster of differentiation (CD) 11c(+) cells (57% in PPs) compared with PBS-treated mice. This treatment was also associated with increased frequencies of T helper 17 (13%) and regulatory T cells (11%) in the MLNs. Treatment with PBS followed by 1 single dose of VSL#3, 18 h before killing, was associated with a 2-fold increase in CD103(+)CD11c(+) dendritic cells in MLNs and PPs.

CONCLUSION

VSL#3 treatment mediates mouse strain-specific alterations in immunologic phenotype in conditions of homeostasis, suggesting that the effects of probiotic bacteria depend on the genetic background of the host.

Intrinsic immunomodulatory effects of low-digestible carbohydrates selectively extend their anti-inflammatory prebiotic potentials

The beneficial effects of carbohydrate-derived fibers are mainly attributed to modulation of the microbiota, increased colonic fermentation, and the production of short-chain fatty acids. We studied the direct immune responses to alimentary fibers in in vitro and in vivo models. Firstly, we evaluated the immunomodulation induced by nine different types of low-digestible fibers on human peripheral blood mononuclear cells. None of the fibers tested induced cytokine production in baseline conditions. However, only one from all fibers almost completely inhibited the production of anti- and proinflammatory cytokines induced by bacteria. Secondly, the impact of short- (five days) and long-term (three weeks) oral treatments with selected fibers was assessed in the trinitrobenzene-sulfonic acid colitis model in mice. The immunosuppressive fiber significantly reduced levels of inflammatory markers over both treatment periods, whereas a nonimmunomodulatory fiber had no effect. The two fibers did not differ in terms of the observed fermentation products and colonic microbiota after three weeks of treatment, suggesting that the anti-inflammatory action was not related to prebiotic properties. Hence, we observed a direct effect of a specific fiber on the murine immune system. This intrinsic, fiber-dependent immunomodulatory potential may extend prebiotic-mediated protection in inflammatory bowel disease.

Bifidobacterium infantis attenuates colitis by regulating T cell subset responses

AIM: to investigate the effect of Bifidobacterium infantis (B. infantis) on the T cell subsets and in attenuating the severity of experimental colitis in mice.

METHODS: Normal BALB/c mice were fed different doses of B. infantis for 3 wk, and T cell subsets and related cytokine profiles in mesenteric lymph nodes (MLNs) were detected by flow cytometry and real-time RT-PCR. Colitis was induced by administration of trinitrobenzene sulfonic acid (TNBS) in mice. Before colitis induction, mice were fed high dose B. infantis for 3 wk. Cytokine profiles in MLNs and histological changes of colonic tissue were examined 6 d after colitis induction.

RESULTS: No significant change in cytokine profiles was observed in normal mice fed low dose B. infantis. However, Th1-related cytokines (IL-2, IFN-γ, IL-12p40), Th17-related transcription factor and cytokines (RORγt, IL-21, IL-23), regulatory T cell (Treg)-related transcription factor and cytokines (Foxp3, IL-10) were increased in normal mice fed high dose B. infantis. Furthermore, flow cytometry assay showed B. infantis increased the numbers of CD4⁺Foxp3⁺ Tregs and Th17 cells in MLNs. Colitis was successfully induced by TNBS in mice, characterized by colonic inflammation and aberrant Th1 and Th17 responses. Feeding high dose B. infantis for 3 wk before colitis induction decreased the inflammatory cell infiltration and goblet cell depletion and restored the intestinal epithelium. In addition, B. infantis feeding reduced Th1-related cytokines (T-bet, IL-2 and IFN-γ) and Th17-related cytokines (IL-12p40, RORγt, IL-17A, IL-21 and IL-23), and increased Treg-related molecules (Foxp3, IL-10 and TGF-β) in colitis mice.

CONCLUSION: B. infantis effectively attenuates TNBS-induced colitis by decreasing Th1 and Th17 responses and increasing Foxp3⁺ Treg response in the colonic mucosa.

Faecalibacterium prausnitzii inhibits interleukin-17 to ameliorate colorectal colitis in rats

Background and Aims

It has been shown that Faecalibacterium prausnitzii (F. prausnitzii), one of the dominant intestinal bacterial flora, may protect colonic mucosa against the development of inflammation and subsequent inflammatory bowel disease (IBD), with the underlying mechanisms being unclear.

Methods

The impacts of F. prausnitzii and its metabolites on IL-23/Th17/IL-17 pathway markers were determined in human monocytes and a rat model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid. F. prausnitzii and its culture medium (containing complete metabolites) were used to treat the rats in vivo, as well as rat splenocytes and human monocytes in vitro. Inflammatory cytokines were measured in colon tissue, plasma and cell culture medium.

Results

The culture supernatant of F. prausnitzii increased plasma anti-Th17 cytokines (IL-10 and IL-12)and suppressed IL-17 levels in both plasma and colonic mucosa, with ameliorated colonic colitis lesions. This inhibition of IL-17 release has also been observed in both rat splenocytes and human venous monocytes in vitro. The culture supernatant of F. prausnitzii also suppressed Th17 cell differentiation induced by cytokines (TGF-ß and IL-6) and bone marrow-derived dendritic cells (BMDCs) in vitro. The metabolites of F. prausnitzii in the culture supernatant exert a stronger anti-inflammatory effect than the bacterium itself. F. prausnitzii protected the colon mucosa against the development of IBD by its metabolites, suggesting a promising potential for the use of F. prausnitzii and its metabolic products in the treatment of IBD.

Induction of murine TNBS colitis is strictly controlled by a modified method using continuous inhalation anesthesia with sevoflurane

BACKGROUND

Trinitrobenzenesulfonic acid (TNBS)-induced colitis is one of the most widely used experimental colitis models. However, there is no standard procedure for inducing colitis by TNBS because it is difficult to achieve a uniform distribution of colitis. We have developed a modified method of murine TNBS-induced colitis that involves inhalation anesthesia with sevoflurane combined with both single and repeated TNBS administrations.

AIMS

To compare the usefulness of our newly developed method for inducing murine TNBS-induced colitis with that of conventional intraperitoneal anesthesia.

METHODS

TNBS in ethanol was administered to C57BL/6J mice held in an inverted vertical position either under continuous inhalation anesthesia with sevoflurane, in accordance with our newly developed method, or by intraperitoneal injection with 2.5 % avertin, in accordance with the conventional procedure. Body weight change, cytokine profile, and histological findings were examined during the course of colitis.

RESULTS

The dispersion of anesthesia time, TNBS retention time, and nadir weight during the course of colitis was decreased using the newly developed method compared with the conventional procedure. Optimization of the modified TNBS-induced colitis, as evidenced by the predominant expression of Th1 and Th17 cytokines on day 7, was attained by the injection of 2.25 mg TNBS in 55 % ethanol. Regulation of the TNBS retention time using inhalation anesthesia with sevoflurane allowed strict control of the disease severity of TNBS-induced colitis. Using the modified method we were also able to develop a chronic TNBS-induced colitis model by repeated TNBS administration without excessive mortality of the mice.

CONCLUSIONS

Our modified method for murine TNBS-induced colitis using continuous inhalation anesthesia with sevoflurane provides a better experimental colitis model following both single and repeated TNBS administrations.

Glutamine downregulates TLR-2 and TLR-4 expression and protects intestinal tract in preterm neonatal rats with necrotizing enterocolitis

BACKGROUND/PURPOSE

Toll-like receptor (TLR)-4 and TLR-2 play an essential role in the pathogenesis of necrotizing enterocolitis (NEC). In this study, we investigated the protective effect of glutamine (Gln) in an NEC neonatal rat model, and the potential association with TLR-4 and TLR-2 expression in local intestinal tissues.

METHODS

Preterm neonatal rats were randomly divided into 3 groups: normal control; NEC model; and NEC plus Gln intervention. NEC was induced by feeding with artificial milk substitutes, plus exposure to hypoxia and cold stress. All preterm rats were sacrificed at 3 days after birth. The intestinal tissues were taken for pathological analysis. Protein and mRNA expression of TLR-2, TLR-4, and caspase-3 was examined by immunohistochemistry and real-time RT-PCR, respectively.

RESULTS

Compared with the normal control, the NEC neonatal rats showed mucosal injury and upregulated mRNA and protein expression of TLR-2, TLR-4, and caspase-3 in ileum and colon. Gln intervention significantly reduced the mucosal injury and suppressed the upregulated expression of TLR-2, TLR-4, and caspace-3 in the ileum and colon of NEC neonatal rats.

CONCLUSIONS

Gln protects the intestinal tract of NEC neonatal rats, which may be associated with the reduction of TLR-2 and TLR-4 expression in intestines.

Effects of interleukin-4 or interleukin-10 gene therapy on trinitrobenzenesulfonic acid-induced murine colitis

Background

Inflammatory bowel disease (IBD) is characterized by disturbance of pro-inflammatory cytokines and anti-inflammatory cytokines. Previous studies have demonstrated the effect of anti-inflammatory cytokines, such as interleukin-10 (IL-10) or IL-4 on IBD, but their data were controversial. This study further investigated the effect of IL-4 (IL-4), IL-10 and their combination on treatment of trinitrobenzenesulfonic acid (TNBS)-induced murine colitis.

Methods

pcDNA3.0 carrying murine IL-4 or IL-10 cDNA was encapsulated with LipofectAMINE 2000 and intraperitoneally injected into mice with TNBS-induced colitis. The levels of intestinal IL-4 and IL-10 mRNA were confirmed by quantitative-RT-PCR. Inflamed tissues were assessed by histology and expression of interferon (IFN)-γ, tumor necrosis factor (TNF)-α and IL-6.

Results

The data confirmed that IL-4 or IL-10 over-expression was successfully induced in murine colon tissues after intraperitoneal injection. Injections of IL-4 or IL-10 significantly inhibited TNBS-induced colon tissue damage, disease activity index (DAI) and body weight loss compared to the control mice. Furthermore, expression of IFN-γ, TNF-α and IL-6 was markedly blocked by injections of IL-4 or IL-10 plasmid. However, there was less therapeutic effect in mice injected with the combination of IL-4 and IL-10.

Conclusions

These data suggest that intraperitoneal injection of IL-4 or IL-10 plasmid was a potential strategy in control of TNBS-induced murine colitis, but their combination had less effect.

Anti-inflammatory properties of Streptococcus salivarius, a commensal bacterium of the oral cavity and digestive tract

Streptococcus salivarius is one of the first colonizers of the human oral cavity and gut after birth and therefore may contribute to the establishment of immune homeostasis and regulation of host inflammatory responses. The anti-inflammatory potential of S. salivarius was first evaluated in vitro on human intestinal epithelial cells and human peripheral blood mononuclear cells. We show that live S. salivarius strains inhibited in vitro the activation of the NF-κB pathway on intestinal epithelial cells. We also demonstrate that the live S. salivarius JIM8772 strain significantly inhibited inflammation in severe and moderate colitis mouse models. These in vitro and in vivo anti-inflammatory properties were not found with heat-killed S. salivarius, suggesting a protective response exclusively with metabolically active bacteria.

M1 is a major subtype of muscarinic acetylcholine receptors on mouse colonic epithelial cells

BACKGROUND

Muscarinic acetylcholine receptors (mAChRs) are major regulators of gut epithelial functions. However, the precise subtype composition has not been clarified.

METHODS

We characterized the pharmacological profile of mAChRs on mouse colonic crypts, employing [(3)H]-N-methyl scopolamine chloride as a radioligand and several subtype-selective chemicals, and the functional aspect by measuring short-circuit current (I sc) in Ussing chambers and by evaluating MAP kinase phosphorylation in mouse colonic mucosal sheets.

RESULTS

The mAChRs were detected on the crypts (K d = 163.2 ± 32.3 pM, B max = 47.3 ± 2.6 fmol/mg of total cell protein). Muscarinic toxin 7 (MT-7, M1 subtype selective) gave a displacement curve with high affinity, but there was a part insensitive to MT-7 (18.8 ± 0.4 % of the total specific binding). The MT-7-insensitive component was displaced completely by darifenacin (M3 selective) with high affinity. ACh induced an increase in I sc, which was significantly enhanced by MT-7 but was completely inhibited by darifenacin or atropine. Colitis induction resulted in a significant decrease in the density of mAChRs, which occurred mainly in the MT-7-sensitive component (M1 subtype). Immunological experiments exhibited a reduction of M1 but not of M3 signal after colitis induction. Muscarinic stimulation induced an increase in MAP kinase phosphorylation, which was completely suppressed by MT-7 and was attenuated by inflammation, in mouse colonic epithelium.

CONCLUSIONS

These results suggest that mAChRs in mouse colonic epithelial cells consist of two subtypes, M1 (80 %) and M3 (20 %). The major M1 subtype was likely to regulate epithelial chloride secretion negatively and was susceptible to inflammation and may be relevant to inflammatory gut dysfunction.

Probiotics can generate FoxP3 T-cell responses in the small intestine and simultaneously inducing CD4 and CD8 T cell activation in the large intestine

Most studies on probiotics aim to restore intestinal homeostasis to reduce immune-pathology in disease. Of equal importance are studies on how probiotics might prevent or delay disease in healthy individuals. However, knowledge on mechanisms of probiotic actions in healthy individuals is scarce. To gain more insight in how different bacterial strains may modulate the healthy intestinal immune system, we investigated the effect of the food derived bacterial strains L. plantarum WCFS1, L. salivarius UCC118, and L. lactis MG1363, on the intestinal regulatory immune phenotype in healthy mice. All three bacterial strains induced an upregulation of activity and numbers of CD11c⁺ MHCII⁺ DCs in the immune-sampling Peyer’s Patches. Only L. salivarius UCC118 skewed towards an immune regulatory phenotype in the small intestinal lamina propria (SILP). The effects were different in the large intestine lamina propria. L. salivarius UCC118 induced activation in both CD4 and CD8 positive T-cells while L. plantarum WCFS1 induced a more regulatory phenotype. Moreover, L. plantarum WCFS1 decreased the Th1/Th2 ratio in the SILP. Also L. lactis MG1363 had immunomodulatory effects. L. lactis MG1363 decreased the expression of the GATA-3 and T-bet in the SILP. As our data show that contradictory effects may occur in different parts of the gut, it is recommended to study effects of probiotic in different sites in the intestine. Our strain-specific results suggest that unspecified application of probiotics may not be very effective. Our data also indicate that selection of specific probiotic strain activities on the basis of responses in healthy mice may be a promising strategy to specifically stimulate or suppress immunity in specific parts of the intestine.

The impact of Lactobacillus plantarum WCFS1 teichoic acid D-alanylation on the generation of effector and regulatory T-cells in healthy mice

To date it remains unclear how probiotics affect the immune system. Bacterial envelope components may play an essential role, as these are the first to establish bacterial-host cell interactions. Teichoic acids (TAs), and especially lipoteichoic acids, are the most pro-inflammatory components of the gram-positive bacterial envelope. This effect is dependent on D-alanyl substitution of the TA backbone and interactions with TLR2 on host cells. Although the pro-inflammatory properties of TAs have been established in vitro, it remains unclear how TAs affect immunomodulation in vivo. In this study, we investigated the role of TA D-alanylation on L. plantarum–induced intestinal and systemic immunomodulation in vivo. For this, we compared the effect of L. plantarum WCFS1 and its TA D-Alanylation negative derivative (dltX-D) on the distribution of dendritic cell and T cell populations and responses in healthy mice. We demonstrated that the majority of the L. plantarum-induced in vivo immunomodulatory effects were dependent on D-alanylation (D-Ala), as some L. plantarum WCFS1-induced immune changes were not observed in the dltX-D-treated group and some were only observed after treatment with dltX-D. Strikingly, not only pro-inflammatory immune responses were abolished in the absence of D-Ala substitution, but also anti-inflammatory responses, such as the L. plantarum-induced generation of regulatory T cells in the spleen. With this study we provide insight in host-microbe interactions, by demonstrating the involvement of D-alanylation of TAs on the bacterial membrane in intestinal and systemic immunomodulation in healthy mice.

Anti-inflammatory Lactobacillus rhamnosus CNCM I-3690 strain protects against oxidative stress and increases lifespan in Caenorhabditis elegans

Numerous studies have shown that resistance to oxidative stress is crucial to stay healthy and to reduce the adverse effects of aging. Accordingly, nutritional interventions using antioxidant food-grade compounds or food products are currently an interesting option to help improve health and quality of life in the elderly. Live lactic acid bacteria (LAB) administered in food, such as probiotics, may be good antioxidant candidates. Nevertheless, information about LAB-induced oxidative stress protection is scarce. To identify and characterize new potential antioxidant probiotic strains, we have developed a new functional screening method using the nematode Caenorhabditis elegans as host. C. elegans were fed on different LAB strains (78 in total) and nematode viability was assessed after oxidative stress (3 mM and 5 mM H(2)O(2)). One strain, identified as Lactobacillus rhamnosus CNCM I-3690, protected worms by increasing their viability by 30% and, also, increased average worm lifespan by 20%. Moreover, transcriptomic analysis of C. elegans fed with this strain showed that increased lifespan is correlated with differential expression of the DAF-16/insulin-like pathway, which is highly conserved in humans. This strain also had a clear anti-inflammatory profile when co-cultured with HT-29 cells, stimulated by pro-inflammatory cytokines, and co-culture systems with HT-29 cells and DC in the presence of LPS. Finally, this Lactobacillus strain reduced inflammation in a murine model of colitis. This work suggests that C. elegans is a fast, predictive and convenient screening tool to identify new potential antioxidant probiotic strains for subsequent use in humans.

Effectiveness of Saccharomyces boulardii in a rat model of colitis

AIM: To investigate the effects of Saccharomyces boulardii (S. boulardii) in an experimental rat model of trinitrobenzene sulfonic acid (TNBS)-induced colitis.

METHODS: Thirty-two Wistar albino female rats were categorized into five groups. On the first day of the study, 50 mg TNBS was administered via a rectal catheter in order to induce colitis in all rats, except those in the control group. For 14 d, the rats were fed a standard diet, without the administration of any additional supplements to either the control or TNBS groups, in addition to 1 mg/kg per day S. boulardii to the S. boulardii group, 1 mg/kg per day methyl prednisolone (MP) to the MP group. The animals in the S. boulardii + MP group were coadministered these doses of S. boulardii and MP. During the study, weight loss, stool consistency, and the presence of obvious blood in the stool were evaluated, and the disease activity index (DAI) for colitis was recorded. The intestines were examined and colitis was macro- and microscopically scored. The serum and tissue levels of tumor necrosis factor-α (TNF-α) and nitric oxide (NO) were determined, and fungemia was evaluated in the blood samples.

RESULTS: The mean DAI scores for the MP and S. boulardii + MP groups was significantly lower than the TNBS group (3.69 ± 0.61 vs 4.46 ± 0.34, P = 0.018 and 3.77 ± 0.73 vs 4.46 ± 0.34, P = 0.025, respectively). While no significant differences between the TNBS and the S. boulardii or MP groups could be determined in terms of serum NO levels, the level of serum NO in the S. boulardii + MP group was significantly higher than in the TNBS and S. boulardii groups (8.12 ± 4.25 μmol/L vs 3.18 ± 1.19 μmol/L, P = 0.013; 8.12 ± 4.25 μmol/L vs 3.47 ± 1.66 μmol/L, P = 0.012, respectively). The tissue NO levels in the S. boulardii, MP and S. boulardii + MP groups were significantly lower than the TNBS group (16.62 ± 2.27 μmol/L vs 29.72 ± 6.10 μmol/L, P = 0.002; 14.66 ± 5.18 μmol/L vs 29.72 ± 6.10 μmol/L, P = 0.003; 11.95 ± 2.34 μmol/L vs 29.72 ± 6.10 μmol/L, P = 0.002, respectively). The tissue NO levels in the S. boulardii, MP and S. boulardii + MP groups were similar. The mean serum and tissue TNF-α levels were determined to be 12.97 ± 18.90 pg/mL and 21.75 ± 15.04 pg/mL in the control group, 18.25 ± 15.44 pg/mL and 25.27 ± 11.95 pg/mL in the TNBS group, 20.59 ± 16.15 pg/mL and 24.39 ± 13.06 pg/mL in the S. boulardii group, 9.05 ± 5.13 pg/mL and 24.46 ± 10.85 pg/mL in the MP group, and 13.95 ± 10.17 pg/mL and 24.26 ± 10.37 pg/mL in the S. boulardii + MP group. Significant differences in terms of the levels of serum and tissue TNF-α and the macroscopic and microscopic scores were not found between the groups. S. boulardii fungemia was not observed in any of the rats. However, Candida fungemia was detected in one rat (14%) in the TNBS group, two rats (28%) in the S. boulardii group, three rats (50%) in the MP group, and three rats (42%) in S. boulardii + MP group.

CONCLUSION: S. boulardii does not demonstrate considerable effects on the DAI, pathological scores, or cytokine levels but does decrease the tissue NO levels.

L. plantarum, L. salivarius, and L. lactis attenuate Th2 responses and increase Treg frequencies in healthy mice in a strain dependent manner

Many studies on probiotics are aimed at restoring immune homeostasis in patients to prevent disease recurrence or reduce immune-mediated pathology. Of equal interest is the use of probiotics in sub-clinical situations, which are characterized by reduced immune function or low-grade inflammation, with an increased risk of infection or disease as a consequence. Most mechanistic studies focus on the use of probiotics in experimental disease models, which may not be informative for these sub-clinical conditions. To gain better understanding of the effects in the healthy situation, we investigated the immunomodulatory effects of two Lactobacillus probiotic strains, i.e. L. plantarum WCFS1 and L. salivarius UCC118, and a non-probiotic lactococcus strain, i.e. L. lactis MG1363, in healthy mice. We studied the effect of these bacteria on the systemic adaptive immune system after 5 days of administration. Only L. plantarum induced an increase in regulatory CD103⁺ DC and regulatory T cell frequencies in the spleen. However, all three bacterial strains, including L. lactis, reduced specific splenic T helper cell cytokine responses after ex vivo restimulation. The effect on IFN-γ, IL5, IL10, and IL17 production by CD4⁺ and CD8⁺ T cells was dependent on the strain administered. A shared observation was that all three bacterial strains reduced T helper 2 cell frequencies. We demonstrate that systemic immunomodulation is not only observed after treatment with probiotic organisms, but also after treatment with non-probiotic bacteria. Our data demonstrate that in healthy mice, lactobacilli can balance T cell immunity in favor of a more regulatory status, via both regulatory T cell dependent and independent mechanisms in a strain dependent manner.

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents

AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice.

METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe²⁺) iron salt or ferric (Fe³⁺) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated using quantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria.

RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg protein vs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.

CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.

Methods of inducing inflammatory bowel disease in mice

Animal models of experimentally induced inflammatory bowel disease (IBD) are useful for understanding more about the mechanistic basis of disease, identifying new targets for therapeutic intervention, and testing novel therapeutic agents. This unit provides detailed protocols for four of the most commonly used mouse models of experimentally induced intestinal inflammation: chemical induction of colitis by dextran sodium sulfate (DSS), hapten-induced colitis via 2,4,6-trinitrobenzene sulfonic acid (TNBS), Helicobacter-induced colitis in mdr1a(-/-) mice, and the CD4(+) CD45RB(hi) SCID transfer colitis model.

Protective effect of Lactobacillus acidophilus on intestinal mucosa of neonatal mice infected with a human rotavirus

AIM: To investigate the possible protective effect of Lactobacillus acidophilus (L.acidophilus) on intestinal mucosa of neonatal mice infected with a human rotavirus (HRV).

METHODS: Sixty 4-day-old Kunming mice were randomly and equally divided into control group, HRV-infected group, L.acidophilus-pretreated group (treated before HRV infection) and L.acidophilus-treated group (treated after HRV infection). The symptoms in these mice were observed each day for 8 d. On day 8, nine mice of each group were sacrificed by cervical dislocation. Caecum samples were taken for bacterial isolation and culture to count bacterial colonies. Secretory IgA (sIgA) from the intestinal mucosa and serum interferon-γ (IFN-γ) and tumor necrosis factors-α (TNF-α) were detected by ELISA. The thickness of intestinal mucosa, height of villus and depth of crypt were measured using Image-Pro Plus 5.1 software.

RESULTS: The mice in the normal control group did not suffer from diarrhea, whereas the HRV-infected group showed altered intestinal flora, decreased level of intestinal sIgA, increased serum IFN-γ and TNF-α levels, and damaged intestinal mucosal barrier. Compared to the HRV-infected group, mice of the L.acidophilus-pretreated and -treated groups showed some amelioration in intestinal flora, intestinal sIgA, serum IFN-γ and TNF-α, and intestinal mucosal barrier. More obvious protective effect on intestinal mucosa was observed in the pretreatment group than in the treatment group.

CONCLUSION: L.acidophilus possesses protective effect on intestinal mucosa of HRV-infected neonatal mice. Pretreatment with L.acidophilus has better protective effect than L.acidophilus treatment.

BTZO-15, an ARE-activator, ameliorates DSS- and TNBS-induced colitis in rats

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that are primarily represented by ulcerative colitis and Crohn's disease. The etiology of IBD is not well understood; however, oxidative stress is considered a potential etiological and/or triggering factor for IBD. We have recently reported the identification of BTZO-1, an activator of antioxidant response element (ARE)-mediated gene expression, which protects cardiomyocytes from oxidative stress-induced insults. Here we describe the potential of BTZO-15, an active BTZO-1 derivative for ARE-activation with a favorable ADME-Tox profile, for the treatment of IBD. BTZO-15 induced expression of heme oxygenase-1 (HO-1), an ARE-regulated cytoprotective protein, and inhibited NO-induced cell death in IEC-18 cells. Large intestine shortening, rectum weight gain, diarrhea, intestinal bleeding, and an increase in rectal myeloperoxidase (MPO) activity were observed in a dextran sulfate sodium (DSS)-induced colitis rat model. Oral administration of BTZO-15 induced HO-1 expression in the rectum and attenuated DSS-induced changes. Furthermore BTZO-15 reduced the ulcerated area and rectal MPO activity in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis rats without affecting rectal TNF-α levels. These results suggest that BTZO-15 is a promising compound for a novel IBD therapeutic drug with ARE activation properties.

Lessons from probiotic-host interaction studies in murine models of experimental colitis

In inflammatory bowel diseases (IBD), it is known that besides genetic and environmental factors (e.g. diet, drugs, stress), the microbiota play an important role in the pathogenesis. Patients with IBD have an altered microbiota (dysbiosis) and therefore, probiotics, defined as 'live micro-organisms that when administered in adequate amounts can confer a health benefit on the host', have been suggested as nutritional supplements to restore these imbalances. The best response on probiotics among the different types of IBD appears to be in the case of ulcerative colitis. Although probiotics show promise in IBD in both clinical and animal studies, further mechanistic studies are necessary to optimize the use of probiotics as supporting therapy in IBD. Murine models of experimental colitis have been used for decades to study this pathology, and these models have been proven useful to search for new therapeutic approaches. The purpose of this review is to summarize probiotic-host interaction studies in murine models of experimental colitis and to evaluate how these models can further help in understanding these complex interactions. Unraveling the molecular mechanisms behind the beneficial effects will assist in better and possibly more efficient probiotic formulations.

Role of probiotics in the management of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a disorder characterized by chronic recurrent colitis. Probiotics have emerged as a new therapy for IBD over the last decade. The efficacy of probiotics in attenuating experimental colitis and preventing clinical relapse had been proved in some animal and human studies but data are still inconsistent. There are many problems to be solved in future studies. This review focuses on recent advances in understanding the role of probiotics in the management of IBD.

Proinflammatory and anti-inflammatory cytokines present in the acute phase of experimental colitis treated with Saccharomyces boulardii

PURPOSE

To study the proinflammatory and anti-inflammatory cytokines present in the acute phase of trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis treated with Saccharomyces boulardii.

METHODS

Thirty male Wistar rats were divided into three groups: (1) treated group--received Saccharomyces boulardii for 14 days; (2) non-treated group--received sodium chloride solution for 14 days; (3) control group. Colitis was induced on the seventh day of the study in the treated and the non-treated groups using TNBS (10 mg) dissolved in 50% ethanol. Quantification of cytokines, including interleukin (IL)-1beta (IL-1beta), IL-6, transforming growth factor-beta (TGF-beta), IL-10 and tumor necrosis factor-alpha (TNF-alpha), in the serum and colonic tissue collected on day 14 were carried out using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

The mean concentrations of TGF-beta in both the serum and the colonic tissue of the treated group were statistically higher than that of the control group. The mean concentration of TGF-beta in the colonic tissue of the non-treated group was also statistically higher than the control group.

CONCLUSION

The group treated with Saccharomyces boulardii showed increased amounts of TGF-beta, an anti-inflammatory cytokine, during the acute phase of colitis. There were no differences in the amount of TNF-alpha, IL-1beta, IL-6, and IL-10 between the treated and the non-treated or the control groups during the acute phase of experimental colitis induced by TNBS.

Probiotic yeasts: Anti-inflammatory potential of various non-pathogenic strains in experimental colitis in mice

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 model of acute 2-4-6-trinitrobenzene sulfonic acid (TNBS)-colitis was next used to evaluate the distinct prophylactic protective capacities of three yeast strains compared with the performance of prednisolone treatment.

RESULTS: The six yeast strains all showed similar non-discriminating anti-inflammatory potential when tested on immunocompetent cells in vitro. However, although they exhibited similar colonization patterns in vivo, some yeast strains showed significant anti-inflammatory activities in the TNBS-induced colitis model, whereas others had weaker or no preventive effect at all, as evidenced by colitis markers (body-weight loss, macroscopic and histological scores, myeloperoxidase activities and blood inflammatory markers).

CONCLUSION: A careful selection of strains is required among the biodiversity of yeasts for specific clinical studies, including applications in inflammatory bowel disease and other therapeutic uses.

Rotavirus-like particles: a novel nanocarrier for the gut

The delivery of bioactive molecules directly to damaged tissues represents a technological challenge. We propose here a new system based on virus-like particles (VLP) from rotavirus, with a marked tropism for the gut to deliver bio-active molecules to intestinal cells. For this, nonreplicative VLP nanoparticles were constructed using a baculovirus expression system and used to deliver an exogenous biomolecule, the green fluorescent protein (GFP), into either MA104 cells or intestinal cells from healthy and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-treated mice. Our results show that expression of rotavirus capsid proteins in baculovirus led to the auto assembly of VLP that display similar properties to rotavirus. In vitro experiments showed that VLP were able to enter into MA104 cells and deliver the reporter protein. Intragastric administration of fluorescent VLP in healthy and TNBS-treated mice resulted in the detection of GFP and viral proteins in intestinal samples. Our results demonstrate an efficient entry of non-replicative rotavirus VLP into the epithelial cell line MA104 and provide the first in vivo evidence of the potential of these nanoparticles as a promising safe candidate for drug delivery to intestinal cells.

Probiotic properties of non-conventional lactic acid bacteria: immunomodulation by Oenococcus oeni

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.