Oral administration of probiotic bacteria (E. coli Nissle, E. coli O83, Lactobacillus casei) influences the severity of dextran sodium sulfate-induced colitis in BALB/c mice

Orange juice containing Pediococcus acidilactici CE51 modulates the intestinal microbiota and reduces induced inflammation in a murine model of colitis

The management of inflammatory bowel diseases has been widely investigated, especially ulcerative colitis. Thus, studies with the application of new probiotic products are needed in the prevention/treatment of these clinical conditions. The objective of this work was to evaluate the effects of probiotic orange juice containing Pediococcus acidilactici CE51 in a murine model of colitis. 45 male Swiss lineage mice were used, divided into five groups (n = 9): control, colitis, colitis + probiotic (probiotic orange juice containing CE51), colitis + placebo (orange juice) and colitis + sulfasalazine (10 mg/kg/Weight). The induction of colitis was performed with dextran sodium sulfate (3%). The treatment time was 5 and 15 days after induction. Histopathological analysis, serum measurements of TNF-α and C-reactive protein and metagenomic analysis of feces were performed after euthanasia. Probiotic treatment reduced inflammation in the small intestine, large intestine and spleen. The probiotic did not alter the serum dosages of TNF-α and C-reactive protein. Their use maintained the quantitative ratio of the phylum Firmicutes/Bacteroidetes and increased Lactobacillus helveticus with 15 days of treatment (p < 0.05). The probiotic orange juice containing P. acidilactici CE51 positively modulated the gut microbiota composition and attenuated the inflammation induced in colitis.

Prevention of DSS-induced colitis in mice with water kefir microbiota via anti-inflammatory and microbiota-balancing activity

Water kefir, a natural and stable functional microbiota system consisting of a symbiotic mixture of probiotics, shows multiple bioactivities but little is known about the effect of water kefir microbiota on the prevention of inflammatory bowel disease (IBD), which is one of the most common intestinal problems and has become a worldwide public health concern. Here, the main objectives of the present study were to investigate the preventative effects of water kefir microbiota, a probiotic consortium mainly consisting of bacteria belonging to Acetobacter, Lactobacillus, and Komagataeibacter and fungi belonging to Saccharomyces and Talaromyces, in a dextran sodium sulfate (DSS)-induced colitis mouse model and unveil the underlying mechanism of the action. Water kefir microbiota effectively improved the disease severity of DSS-induced colitis, including decreased body weight and colon length, increased spleen index and DAI score, and colonic tissue damage. Moreover, water kefir microbiota restored the abnormal expression of tight junction proteins (such as occludin, ZO-1, and claudin-1) and pro-inflammatory and anti-inflammatory cytokines (such as IL-1β, IL-6, TNF-α, COX-2, iNOS, and IL-10) and inactivated TLR4-MyD88-NF-κB pathway induced by DSS. Water kefir microbiota also improved the composition and metabolism of intestinal microbiota. These findings demonstrated that water kefir microbiota could exert protective roles in the DSS-induced colitis mouse model by reducing inflammation and regulating microbial dysbiosis, which will be helpful for the development of water kefir microbiota-based microbial products as an alternative preventative strategy for IBD.

Evaluation of microbial and vancomycin treatments in ulcerative colitis in murine models

BACKGROUND

Despite the number of available therapies for ulcerative colitis (UC), severe side effects and high cost has limited their clinical application. Thus, finding new alternative strategies with minimal side effects is inevitable. Therefore, this study aimed to compare the effectiveness of different therapeutic approaches in DSS-induced colitis.

METHODS

Firstly, we designed oral bio-therapeutic products, Live Bacterial Products (LBP), which include a mixture of fecal bacteria strains isolated from healthy mice and prepared by microencapsulation and freeze-dried techniques. Then we investigated the efficiency of 7 days of freeze-dried FMT, LBP, and vancomycin treatments in DSS-induced colitis. Secondly, we compared the effect of 15 days of microbial therapies (freeze-dried powder of FMT and LBP microcapsules) and seven days of oral vancomycin on the severity of colitis in mice. Furthermore, the levels of IL-1β and TNF-α were measured in serum by ELISA, and the fecal microbiota diversity was analyzed by high-throughput sequencing for all mice groups.

RESULTS

After seven days of treatments, our results indicated that oral vancomycin reduced the severity of DSS-induced colitis in mice, where weight gain and a decrease in IL-1 β and TNF-α levels were observed in the vancomycin group compared with other treatment groups. While after two weeks of treatment, the LBP microcapsules were able to reduce the severity of colitis. And at the end of the treatment period, weight gain and a decrease in the DAI scores and the levels of IL-1β and TNF-α were noted in the LBP treatment group compared to other treatment groups. By high-throughput sequencing of the 16S rRNA gene, our results showed that while the microcapsules LBP treatment increased the fecal microbial diversity, after vancomycin therapy, most of the fecal microbiota genera and operational taxonomic units (OTUs) were depleted.

CONCLUSION

Our results concluded that treatment duration and preparation methods affect the microbial therapies' efficiency in UC. Furthermore, this study highlighted the negative consequences of oral vancomycin administration on gut health that should be known before using this medication.

The Impact of Escherichia coli Probiotic Strain O83:K24:H31 on the Maturation of Dendritic Cells and Immunoregulatory Functions In Vitro and In Vivo

Early postnatal events are important for the development of the neonatal immune system. Harboring the pioneering microorganisms forming the microbiota of the neonatal gastrointestinal tract is important for priming the immune system, as well as inducing appropriate tolerance to the relatively innocuous environmental antigens and compounds of normal healthy microbiota. Early postnatal supplementation of suitable, safe probiotics could accelerate this process. In the current study, the immunomodulatory capacity of the probiotic strain of Escherichia coli O83:K24:H31 (EcO83) was characterized in vitro and in vivo. We compared the capacity of EcO83 with and without hemolytic activity on selected immune characteristics in vitro as determined by flow cytometry and quantitative real-time PCR. Both strains with and without hemolytic activity exerted comparable capacity on the maturation of dendritic cells while preserving the induction of interleukin 10 (Il10) expression in dendritic cells and T cells cocultured with EcO83 primed dendritic cells. Early postnatal supplementation with EcO83 led to massive but transient colonization of the neonatal gastrointestinal tract, as detected by in vivo bioimaging. Early postnatal EcO83 administration promoted gut barrier function by increasing the expression of claudin and occludin and the expression of Il10. Early postnatal EcO83 application promotes maturation of the neonatal immune system and promotes immunoregulatory and gut barrier functions.

Fluorescent sensors of siderophores produced by bacterial pathogens

Siderophores are iron-chelating molecules that solubilize Fe³⁺ for microbial utilization and facilitate colonization or infection of eukaryotes by liberating host iron for bacterial uptake. By fluorescently labeling membrane receptors and binding proteins, we created 20 sensors that detect, discriminate, and quantify apo- and ferric siderophores. The sensor proteins originated from TonB-dependent ligand-gated porins (LGPs) of Escherichia coli (Fiu, FepA, Cir, FhuA, IutA, BtuB), Klebsiella pneumoniae (IroN, FepA, FyuA), Acinetobacter baumannii (PiuA, FepA, PirA, BauA), Pseudomonas aeruginosa (FepA, FpvA), and Caulobacter crescentus (HutA) from a periplasmic E. coli binding protein (FepB) and from a human serum binding protein (siderocalin). They detected ferric catecholates (enterobactin, degraded enterobactin, glucosylated enterobactin, dihydroxybenzoate, dihydroxybenzoyl serine, cefidericol, MB-1), ferric hydroxamates (ferrichromes, aerobactin), mixed iron complexes (yersiniabactin, acinetobactin, pyoverdine), and porphyrins (hemin, vitamin B12). The sensors defined the specificities and corresponding affinities of the LGPs and binding proteins and monitored ferric siderophore and porphyrin transport by microbial pathogens. We also quantified, for the first time, broad recognition of diverse ferric complexes by some LGPs, as well as monospecificity for a single metal chelate by others. In addition to their primary ferric siderophore ligands, most LGPs bound the corresponding aposiderophore with ∼100-fold lower affinity. These sensors provide insights into ferric siderophore biosynthesis and uptake pathways in free-living, commensal, and pathogenic Gram-negative bacteria.

MICROBIOME AND UVEITIDES. A REVIEW

Microorganisms inhabiting all surfaces of mucous membranes and skin and forming a complex ecosystem with the host is called microbiota. The term microbiome is used for the aggregate genome of microbiota. The microbiota plays important role in the mechanisms of number of physiological and pathological processes, especially of the hosts immune system. The origin and course of autoimmune diseases not only of the digestive tract, but also of the distant organs, including the eye, are significantly influenced by intestinal microbiota. The role of microbiota and its changes (dysbiosis) in the etiopathogenesis of uveitis has so far been studied mainly in experimental models. Reduction of severity of non-infectious intraocular inflammation in germ-free mice or in conventional mice treated with broad-spectrum antibiotics was observed in both the induced experimental autoimmune uveitis model (EAU) and the spontaneous R161H model. Studies have confirmed that autoreactive T cell activation occurs in the intestinal wall in the absence of retinal antigen. Recent experiments focused on the effect of probiotic administration on the composition of intestinal microbiota and on the course of autoimmune uveitis. Our study group demonstrated significant prophylactic effect of the administration of the probiotic Escherichia coli Nissle 1917 on the intensity of inflammation in EAU. To date, only a few studies have been published investigating intestinal dysbiosis in patients with uveitis (e.g., in Behcets disease or Vogt-Koyanagi-Harada syndrome). The results of preclinical studies will be presumably used in clinical practice, mainly in the sense of prophylaxis and therapy, such as change in the lifestyle, diet and especially the therapeutic use of probiotics or the transfer of faecal microbiota.

The Effect of Lactobacillus casei on Experimental Porcine Inflammatory Bowel Disease Induced by Dextran Sodium Sulphate

BACKGROUND

Gastrointestinal injury caused by dextran sodium sulphate (DSS) is a reliable porcine experimental model of inflammatory bowel disease (IBD). The purpose of this study was to evaluate the effect of probiotic Lactobacillus casei DN 114001 (LC) on DSS-induced experimental IBD.

RESULTS

Eighteen female pigs (Sus scrofa f. domestica, weight 33-36 kg, age 4-5 months) were divided into 3 groups (6 animals per group): controls with no treatment, DSS, and DSS + LC. LC was administered to overnight fasting animals in a dietary bolus in the morning on days 1-7 (4.5 × 1010 live bacteria/day). DSS was applied simultaneously on days 3-7 (0.25 g/kg/day). On day 8, the pigs were sacrificed. Histopathological score and length of crypts/glands (stomach, jejunum, ileum, transverse colon), length and width of villi (jejunum, ileum), and mitotic and apoptotic indices (jejunum, ileum, transverse colon) were assessed. DSS increased the length of glands in the stomach, length of crypts and villi in the jejunum and ileum, and the histopathological score of gastrointestinal damage, length of crypts and mitotic activity in the transverse colon. Other changes did not achieve any statistical significance. Administration of LC reduced the length of villi in the jejunum and ileum to control levels and decreased the length of crypts in the jejunum.

CONCLUSIONS

Treatment with a probiotic strain of LC significantly accelerated regeneration of the small intestine in a DSS-induced experimental porcine model of IBD.

Tryptophan metabolites modulate inflammatory bowel disease and colorectal cancer by affecting immune system

Tryptophan is an essential amino acid, going through three different metabolic pathways in the intestines. Indole pathway in the gut microbiota, serotonin system in the enterochromaffin cells and kynurenine pathway in the immune cells and intestinal lining are the three arms of tryptophan metabolism in the intestines. Clinical, in vivo and in vitro studies showed that each one of these arms has a significant impact on IBD. This review explains how different metabolites of tryptophan are involved in the pathophysiology of IBD and colorectal cancer, as a major complication of IBD. Indole metabolites alleviate colitis and protect against colorectal cancer while serotonin arm follows a more complicated and receptor-specific pattern. Indole metabolites and kynurenine interact with aryl hydrocarbon receptor (AHR) to induce T regulatory cells differentiation, confine Th17 and Th1 response and produce anti-inflammatory mediators. Kynurenine decreases tumor-infiltrating CD8+ cells and mediates tumor cells immune evasion. Serotonin system also increases colorectal cancer cells proliferation and metastasis while, indole metabolites can profoundly decrease colorectal cancer growth. Targeted therapy for tryptophan metabolites may improve the management of IBD and colorectal cancer, e.g. supplementation of indole metabolites such as indole-3-carbinol (I3C), inhibition of kynurenine monooxygenase (KMO) and selective stimulation or inhibition of specific serotonergic receptors can mitigate colitis. Furthermore, it will be explained how indole metabolites supplementation, inhibition of indoleamine 2,3-dioxygenase 1 (IDO1), KMO and serotonin receptors can protect against colorectal cancer. Additionally, extensive molecular interactions between tryptophan metabolites and intracellular signaling pathways will be thoroughly discussed.

Iron Acquisition Systems of Gram-negative Bacterial Pathogens Define TonB-Dependent Pathways to Novel Antibiotics

Iron is an indispensable metabolic cofactor in both pro- and eukaryotes, which engenders a natural competition for the metal between bacterial pathogens and their human or animal hosts. Bacteria secrete siderophores that extract Fe3+ from tissues, fluids, cells, and proteins; the ligand gated porins of the Gram-negative bacterial outer membrane actively acquire the resulting ferric siderophores, as well as other iron-containing molecules like heme. Conversely, eukaryotic hosts combat bacterial iron scavenging by sequestering Fe3+ in binding proteins and ferritin. The variety of iron uptake systems in Gram-negative bacterial pathogens illustrates a range of chemical and biochemical mechanisms that facilitate microbial pathogenesis. This document attempts to summarize and understand these processes, to guide discovery of immunological or chemical interventions that may thwart infectious disease.

Severity of Experimental Autoimmune Uveitis Is Reduced by Pretreatment with Live Probiotic Escherichia coli Nissle 1917

Non-infectious uveitis is considered an autoimmune disease responsible for a significant burden of blindness in developed countries and recent studies have linked its pathogenesis to dysregulation of the gut microbiota. We tested the immunomodulatory properties of two probiotics, Escherichia coli Nissle 1917 (EcN) and E. coli O83:K24:H31 (EcO), in a model of experimental autoimmune uveitis (EAU). To determine the importance of bacterial viability and treatment timing, mice were orally treated with live or autoclaved bacteria in both preventive and therapeutic schedules. Disease severity was assessed by ophthalmoscopy and histology, immune phenotypes in mesenteric and cervical lymph nodes were analyzed by flow cytometry and the gut immune environment was analyzed by RT-PCR and/or gut tissue culture. EcN, but not EcO, protected against EAU but only as a live organism and only when administered before or at the time of disease induction. Successful prevention of EAU was accompanied by a decrease in IRBP-specific T cell response in the lymph nodes draining the site of immunization as early as 7 days after the immunization and eye-draining cervical lymph nodes when the eye inflammation became apparent. Furthermore, EcN promoted an anti-inflammatory response in Peyer’s patches, increased gut antimicrobial peptide expression and decreased production of inducible nitric oxide synthase in macrophages. In summary, we show here that EcN controls inflammation in EAU and suggest that probiotics may have a role in regulating the gut–eye axis.

The effect of selected Lactobacillus strains on dextran sulfate sodium-induced mouse colitis model

Inflammatory bowel disease (IBD) comprises two major illnesses: Crohn's disease (CD) and ulcerative colitis (UC). Dextran sulfate sodium (DSS) mouse colitis model has been used in understanding the mechanism of IBD. This study was conducted to examine selected Lactobacillus spp. as potential IBD treatment in the DSS-induced animal model. Balb/c mice were used and colitis was induced by adding 5% dextran sodium sulfate into the drinking water for 8 days. Colon length, disease activity index (DAI) and histological analysis were measured as markers of inflammation in DSS colitis mice. The majority of the Lactobacillus species significantly prevented the shortening of the colon length compared with the DSS group. The DAI scores of mice were significantly reduced following usage of four Lactobacillus strains included: Lactobacillus plantarum 03 and 06, Lactobacillus brevis 02 and Lactobacillus rhamnosus 01. The histological analysis exhibited that oral administration of Lactobacillus strains had therapeutic effects on mice colitis. L. plantarum and L. brevis showed better therapeutic effect against DSS-induced acute colitis mice. The probiotic activities of these three isolates indicated that the probiotic effects were strain specific and none of these useful bacteria could exhibit all of the valued probiotic properties simultaneously.

Lactobacillus casei LH23 modulates the immune response and ameliorates DSS-induced colitis via suppressing JNK/p-38 signal pathways and enhancing histone H3K9 acetylation

Probiotics are thought to have immunomodulatory functions, improve inflammatory disorders and treat inflammatory bowel disease (IBD).

Lysates of Lactobacillus acidophilus combined with CTLA-4-blocking antibodies enhance antitumor immunity in a mouse colon cancer model

Previous reports have suggested that many gut microbiomes were associated with the development of colorectal cancer (CRC), and could modulate response to numerous forms of cancer therapy, including checkpoint blockade immunotherapy. Here we evaluated the protective efficacy of Lactobacillus acidophilus (L. acidophilus) cell lysates combined with an anti-CTL antigen-4 blocking antibody (CTLA-4 mAb) in syngeneic BALB/c mice CRC models induce by a single intraperitoneal injection of 10 mg/kg azoxymethane (AOM), followed by three cycles of 2% dextran sulfate sodium (DSS) in drinking water. In contrast to CTLA-4 mAb monotherapy, L. acidophilus lysates could attenuate the loss of body weight and the combined administration significantly protected mice against CRC development, which suggested that the lysates enhanced antitumor activity of CTLA-4 mAb in model mice. The enhanced efficacy was associated with the increased CD8 + T cell, increased effector memory T cells (CD44 + CD8 + CD62L+), decreased Treg (CD4 + CD25 + Foxp3+) and M2 macrophages (F4/80 + CD206+) in the tumor microenvironment. In addition, our results revealed that L. acidophilus lysates had an immunomodulatory effect through inhibition the M2 polarization and the IL-10 expressed levels of LPS-activated Raw264.7 macrophages. Finally, the 16S rRNA gene sequencing of fecal microbiota demonstrated that the combined administration significantly inhibited the abnormal increase in the relative abundance of proteobacteria and partly counterbalance CRC-induced dysbiosis in model mice. Overall, these data support promising clinical possibilities of L. acidophilus lysates with CTLA-4 mAb in cancer patients and the hypothesis that probiotics help shape the anticancer immune response.

Effect of dietary probiotics on colon length in an inflammatory bowel disease-induced murine model: A meta-analysis

We investigated the effect of probiotic supplementation on inflammatory bowel disease (IBD) by meta-analysis. We included 30 studies to assess the effect of probiotic administration. We estimated the effect size using standardized mean difference, and we evaluated the statistical heterogeneity of the effect size using Cochran's Q test, followed by meta-ANOVA and meta-regression analysis to explain the heterogeneity of the effect size using a mixed-effects model. We conducted Egger's linear regression test to evaluate publication bias. Among the factors evaluated, colon length and myeloperoxidase showed the greatest Q statistic and I² index, respectively. Colon length, transforming growth factor-β, IL-10, superoxide dismutase, and glutathione showed positive effect sizes in the fixed- and random-effects models. The others (spleen weight, tumor necrosis factor α, IL-1β, IL-6, IL-12, IL-17, IFN-γ, disease activity index, thiobarbituric acid reactive substances, nitric oxide, myeloperoxidase, malondialdehyde, histological score, and macroscopic inflammatory score) showed negative effect sizes in the fixed- and random-effects models. Probiotics showed a significant effect on all investigated factors, except IL-10. In meta-ANOVA and meta-regression analysis, Lactobacillus paracasei was the most effective probiotic for colon length. Lactobacillus paracasei, Lactobacillus reuteri, Lactobacillus fermentum, and a mixture of Lactobacillus bulgaricus and Saccharomyces boulardii (LC + SB) were effective for colon length, tumor necrosis factor α, IL-6, IL-10, IFN-γ, and disease activity index. Lactobacillus rhamnosus was most effective for IL-10 and IFN-γ. Dietary probiotics are effective in improving the symptoms of IBD. Although the results of this meta-analysis had some limitations due to a lack of animal experiments, they will be meaningful to people with IBD.

The immunomodulatory role of probiotics in allergy therapy

The increased incidence of allergic disorders may be the result of a relative fall in microbial induction in the intestinal immune system during infancy and early childhood. Probiotics have recently been proposed as viable microorganisms for the prevention and treatment of specific allergic diseases. Different mechanisms have been considered for this probiotic property, such as generation of cytokines from activated pro-T-helper type 1 after bacterial contact. However, the effects of its immunomodulatory potential require validation for clinical applications. This review will focus on the currently available data on the benefits of probiotics in allergy disease.

Using murine colitis models to analyze probiotics-host interactions

Probiotics are defined as 'live microorganisms which when administered in adequate amounts confer a health benefit on the host'. So, to consider a microorganism as a probiotic, a demonstrable beneficial effect on the health host should be shown as well as an adequate defined safety status and the capacity to survive transit through the gastrointestinal tract and to storage conditions. In this review, we present an overview of the murine colitis models currently employed to test the beneficial effect of the probiotic strains as well as an overview of the probiotics already tested. Our aim is to highlight both the importance of the adequate selection of the animal model to test the potential probiotic strains and of the value of the knowledge generated by these in vivo tests.

Role and mechanisms of action of Escherichia coli Nissle 1917 in the maintenance of remission in ulcerative colitis patients: An update

Ulcerative colitis (UC) is a chronic inflammatory disease, whose etiology is still unclear. Its pathogenesis involves an interaction between genetic factors, immune response and the “forgotten organ”, Gut Microbiota. Several studies have been conducted to assess the role of antibiotics and probiotics as additional or alternative therapies for Ulcerative Colitis. Escherichia coli Nissle (EcN) is a nonpathogenic Gram-negative strain isolated in 1917 by Alfred Nissle and it is the active component of microbial drug Mutaflor^® (Ardeypharm GmbH, Herdecke, Germany and EcN, Cadigroup, In Italy) used in many gastrointestinal disorder including diarrhea, uncomplicated diverticular disease and UC. It is the only probiotic recommended in ECCO guidelines as effective alternative to mesalazine in maintenance of remission in UC patients. In this review we propose an update on the role of EcN 1917 in maintenance of remission in UC patients, including data about efficacy and safety. Further studies may be helpful for this subject to further the full use of potential of EcN.

Different Effects of Three Selected Lactobacillus Strains in Dextran Sulfate Sodium-Induced Colitis in BALB/c Mice

Aim

To analyze the changes of different Lactobacillus species in ulcerative colitis patients and to further assess the therapeutic effects of selected Lactobacillus strains on dextran sulfate sodium (DSS)-induced experimental colitis in BALB/c mice.

Methods

Forty-five active ulcerative colitis (UC) patients and 45 population-based healthy controls were enrolled. Polymerase chain reaction (PCR) amplification and real-time PCR were performed for qualitative and quantitative analyses, respectively, of the Lactobacillus species in UC patients. Three Lactobacillus strains from three species were selected to assess the therapeutic effects on experimental colitis. Sixty 8-week-old BALB/c mice were divided into six groups. The five groups that had received DSS were administered normal saline, mesalazine, L. fermentum CCTCC M206110 strain, L. crispatus CCTCC M206119 strain, or L. plantarum NCIMB8826 strain. We assessed the severity of colitis based on disease activity index (DAI), body weight loss, colon length, and histologic damage.

Results

The detection rate of four of the 11 Lactobacillus species decreased significantly (P < 0.05), and the detection rate of two of the 11 Lactobacillus species increased significantly (P < 0.05) in UC patients. Relative quantitative analysis revealed that eight Lactobacillus species declined significantly in UC patients (P < 0.05), while three Lactobacillus species increased significantly (P < 0.05). The CCTCC M206110 treatment group had less weight loss and colon length shortening, lower DAI scores, and lower histologic scores (P < 0.05), while the CCTCC M206119 treatment group had greater weight loss and colon length shortening, higher histologic scores, and more severe inflammatory infiltration (P < 0.05). NCIMB8826 improved weight loss and colon length shortening (P < 0.05) with no significant influence on DAI and histologic damage in the colitis model.

Conclusions

Administration of an L. crispatus CCTCC M206119 supplement aggravated DSS-induced colitis. L. fermentum CCTCC M206110 proved to be effective at attenuating DSS-induced colitis. The potential probiotic effect of L. plantarum NCIMB8826 on UC has yet to be assessed.

Immunoprotective Effect of Probiotic Dahi Containing Lactobacillus acidophilus and Bifidobacterium bifidum on Dextran Sodium Sulfate-Induced Ulcerative Colitis in Mice

In the present study, probiotic Dahi (LaBb Dahi) containing Lactobacillus acidophilus LaVK2 and Bifidobacterium bifidum BbVK3 was selected as a probiotic therapy to investigate its protective effect on dextran sodium sulfate (DSS)-induced ulcerative colitis model in mice that mimics the picture in human. LaBb Dahi was prepared by co-culturing Dahi bacteria (Lactococcus lactis ssp. cremoris NCDC-86 and Lactococcus lactis ssp. lactis biovar diacetylactis NCDC-60) along with selected strain of L. acidophilus LaVK2 and B. bifidum BbVK3 in buffalo milk (3% fat). Four groups of swiss albino male mice (12 each) were fed buffalo milk (3% fat), buffalo milk (3% fat) plus DSS, Dahi plus DSS, and LaBb Dahi plus DSS, respectively, for 17 days with basal diet. The myeloperoxidase (MPO) activity, levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interferon (IFN-γ) were assessed as inflammatory markers, and the histopathological picture of the colon of mice was studied. DSS-induced colitis appeared to induce significant increase in MPO activity, levels of TNF-α, IL-6 and IFN-γ. Feeding with LaBb Dahi offered significant reduction in MPO activity, levels of TNF-α, IL-6 and IFN-γ when compared to either buffalo milk group or group III (Dahi). The present study suggests that LaBb probiotic Dahi can be used to combat DSS-induced biochemical and histological changes and to achieve more effective treatment for ulcerative colitis.

Attenuation of Colitis by Lactobacillus casei BL23 Is Dependent on the Dairy Delivery Matrix

The role of the food delivery matrix in probiotic performance in the intestine is not well understood. Because probiotics are often provided to consumers in dairy products, we investigated the contributions of milk to the health-benefiting performance of Lactobacillus casei BL23 in a dextran sulfate sodium (DSS)-induced murine model of ulcerative colitis. L. casei BL23 protected against the development of colitis when ingested in milk but not in a nutrient-free buffer simulating consumption as a nutritional supplement. Consumption of (acidified) milk alone also provided some protection against weight loss and intestinal inflammation but was not as effective as L. casei and milk in combination. In contrast, L. casei mutants deficient in DltD (lipoteichoic acid d-alanine transfer protein) or RecA (recombinase A) were unable to protect against DSS-induced colitis, even when consumed in the presence of milk. Mice fed either L. casei or milk contained reduced quantities of colonic proinflammatory cytokines, indicating that the L. casei DltD(-) and RecA(-) mutants as well as L. casei BL23 in nutrient-free buffer were effective at modulating immune responses. However, there was not a direct correlation between colitis and quantities of these cytokines at the time of sacrifice. Identification of the cecal microbiota by 16S rRNA gene sequencing showed that L. casei in milk enriched for Comamonadaceae and Bifidobacteriaceae; however, the consumption of neither L. casei nor milk resulted in the restoration of the microbiota to resemble that of healthy animals. These findings strongly indicate that probiotic strain efficacy can be influenced by the food/supplement delivery matrix.

Monocolonization of germ-free mice with Bacteroides fragilis protects against dextran sulfate sodium-induced acute colitis

Ulcerative colitis is inflammatory conditions of the colon caused by interplay of genetic and environmental factors. Previous studies indicated that the gut microflora may be involved in the colonic inflammation. Bacteroides fragilis (BF) is a Gram-negative anaerobe belonging to the colonic symbiotic. We aimed to investigate the protective role of BF in a colitis model induced in germ-free (GF) mice by dextran sulfate sodium (DSS). GF C57BL/6JNarl mice were colonized with BF for 28 days before acute colitis was induced by DSS. BF colonization significantly increased animal survival by 40%, with less reduction in colon length, and decreased infiltration of inflammatory cells (macrophages and neutrophils) in colon mucosa following challenge with DSS. In addition, BF could enhance the mRNA expression of anti-inflammatory-related cytokine such as interleukin 10 (IL-10) with polymorphism cytokine IL-17 and diminish that of proinflammatory-related tumor necrosis factor α with inducible nitric oxide synthase in the ulcerated colon. Myeloperoxidase activity was also decreased in BF-DSS mice. Taking these together, the BF colonization significantly ameliorated DSS-induced colitis by suppressing the activity of inflammatory-related molecules and inducing the production of anti-inflammatory cytokines. BF may play an important role in maintaining intestinal immune system homeostasis and regulate inflammatory responses.

Transport proteins promoting Escherichia coli pathogenesis

Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies.

Efficacy profiles for different concentrations of Lactobacillus acidophilus in experimental colitis

AIM: To determine the efficacy profiles of different concentrations of Lactobacillus acidophilus (L. acidophilus) for treating colitis using an experimental murine model.

METHODS: Colitis was established in 64 BALB/c mice by adding 5% dextran sodium sulfate (DSS) to the drinking water and allowing ad libitum access for 7 d. The mice were then randomly divided into the following control and experimental model groups (n = 8 each; day 0): untreated model control; negative-treatment model control (administered gavage of 1 mL/10 g normal saline); experimental-treatment models C4-C8 (administered gavage of 10⁴, 10⁵, 10⁶, 10⁷, or 10⁸ CFU/10 g L. acidophilus, respectively); positive-treatment model control (administration of the anti-inflammatory agent prednisone acetate at 45 μg/10 g). Eight mice given regular water (no DSS) and no subsequent treatments served as the normal control group. Body weight, fecal traits, and presence of fecal occult blood were assessed daily. All animals were sacrificed on post-treatment day 7 to measure colonic length, perform histological scoring, and quantify the major bacteria in the proximal and distal colon. Intergroup differences were determined by one-way ANOVA and post-hoc Student-Newman-Keuls comparison.

RESULTS: All treatments (L. acidophilus and prednisone acetate) protected against colitis-induced weight loss (P < 0.05 vs model and normal control groups). The extent of colitis-induced colonic shortening was significantly reduced by all treatments (prednisone acetate > C4 > C5 > C7 > C8 > C6; P < 0.05 vs untreated model group), and the C6 group showed colonic length similar to that of the normal control group (P > 0.05). The C6 group also had the lowest disease activity index scores among the model groups. The bacterial profiles in the proximal colon were similar between all of the experimental-treatment model groups (all P > 0.05). In contrast, the bacterial profile in the distal colon of the C6 group showed the distinctive features (P < 0.05 vs all other experimental-treatment model groups) of Lactobacillus sp. and Bifidobacterium sp. being the most abundant bacteria and Staphylococcus aureus being the least abundant bacteria.

CONCLUSION: The most therapeutically efficacious concentration of L. acidophilus (10⁶ CFU/10 g) may exert its effects by modulating the bacterial profile in the distal colon.

Exploring the ameliorative potential of probiotic Dahi containing Lactobacillus acidophilus and Bifidobacterium bifidum on dextran sodium sulphate induced colitis in mice

Conventional medical therapies for ulcerative colitis (UC) are still limited due to the adverse side effects like dose-dependent diarrhoea and insufficient potency to keep in remission for long-term periods. So, new alternatives that provide more effective and safe therapies for ulcerative colitis are constantly being sought. In the present study, probiotic LaBb Dahi was selected for investigation of its therapeutic effect on DSS-induced colitis model in mice. LaBb Dahi was prepared by co-culturing Dahi culture of Lactococci along with selected strain of Lactobacillus acidophilus LaVK2 and Bifidobacterium bifidum BbVK3 in buffalo milk. Four groups of mice (12 each) were fed for 17 d with buffalo milk (normal control), buffalo milk plus DSS (Colitis control), Dahi plus DSS, and LaBb Dahi plus DSS, respectively, with basal diet. The disease activity scores, weight loss, organ weight, colon length, myeloperoxidase (MPO) and β-glucoronidase activity was assessed, and the histopathological picture of the colon of mice was studied. All colitis control mice evidenced significant increase in MPO, β-glucoronidase activity and showed high disease activity scores along with histological damage to colonic tissue. Feeding with LaBb Dahi offered significant reduction in MPO activity, β-glucoronidase activity and improved disease activity scores. We found significant decline in length of colon, organ weight and body weight in colitis induced controls which were improved significantly by feeding LaBb Dahi. The present study suggests that LaBb Dahi can be used as a potential nutraceutical intervention to combat UC related changes and may offer effective adjunctive treatment for management of UC.

Factors influencing the development of animal models of dextran sulphate sodium-induced colitis

The animal models of dextran sulphate sodium (DSS)-induced colitis have demonstrated several correlations with human ulcerative colitis (UC) since the first report of DSS-induced colitis in hamsters in 1985. These animal models have similarities to human UC in etiology, pathology, pathogenesis and therapeutic response, and are deemed suitable for investigating the pathogenesis and therapeutic options of UC and UC-related dysplasia-adenocarcinoma sequence. Although induction of colitis with DSS is relatively cheap and simple, the development of this model is influenced by many factors, such as DSS concentration, administration duration, DSS molecular weight and animal species. These factors are important for successful development of DSS-induced colitis. In this paper we summarize factors influencing the development of animal models of DSS-induced colitis.

Lysate of probiotic Lactobacillus casei DN-114 001 ameliorates colitis by strengthening the gut barrier function and changing the gut microenvironment

Background

Probiotic bacteria can be used for the prevention and treatment of human inflammatory diseases including inflammatory bowel diseases (IBD). However, the nature of active components and exact mechanisms of this beneficial effects have not been fully elucidated. Our aim was to investigate if lysate of probiotic bacterium L. casei DN-114 001 (Lc) could decrease the severity of intestinal inflammation in a murine model of IBD.

Methodology/Principal Findings

The preventive effect of oral administration of Lc significantly reduces the severity of acute dextran sulfate sodium (DSS) colitis in BALB/c but not in SCID mice. In order to analyze how this beneficial effect interferes with well-known phases of intestinal inflammation pathogenesis in vivo and in vitro, we evaluated intestinal permeability using the FITC-labeled dextran method and analysed tight junction proteins expression by immunofluorescence and PCR. We also measured CD4⁺FoxP3⁺ regulatory T cells proportion by FACS analysis, microbiota composition by pyrosequencing, and local cytokine production by ELISA. Lc leads to a significant protection against increased intestinal permeability and barrier dysfunction shown by preserved ZO-1 expression. We found that the Lc treatment increases the numbers of CD4⁺FoxP3⁺ regulatory T cells in mesenteric lymph nodes (MLN), decreases production of pro-inflammatory cytokines TNF-α and IFN-γ, and anti-inflammatory IL-10 in Peyer's patches and large intestine, and changes the gut microbiota composition. Moreover, Lc treatment prevents lipopolysaccharide-induced TNF-α expression in RAW 264.7 cell line by down-regulating the NF-κB signaling pathway.

Conclusion/Significance

Our study provided evidence that even non-living probiotic bacteria can prevent the development of severe forms of intestinal inflammation by strengthening the integrity of intestinal barrier and modulation of gut microenvironment.

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.

Salmonella-mediated gene therapy in experimental colitis in mice

Bacterial gene therapy - bactofection is a simple and effective method to deliver plasmid DNA into target tissue. We hypothesize that oral in vivo bactofection can be an interesting approach to influence the course of inflammatory bowel diseases. The aim of this study was to prove the effects of antioxidative and anti-inflammatory bactofection in dextran sulfate sodium (DSS)-treated mice. Attenuated bacteria Salmonella Typhimurium SL7207 carrying plasmids with genes encoding Cu-Zn superoxide dismutase and an N-terminal deletion mutant of monocyte chemoattractant protein-1 were prepared. Male Balb/c mice had ad libitum access to 1% DSS solution in drinking water during 10 days (mild model of colitis). The animals were daily fed with 200 Mio bacteria via gastric gavage during the experiment. Fecal consistency, clinical status, food and water intake were monitored. After 10 days samples were taken and markers of oxidative stress and inflammatory cytokine levels were measured. Colonic tissue was scored histologically by a blinded investigator. DSS treatment significantly increased the levels of inflammatory cytokines and malondialdehyde as a marker of lipoperoxidation in the colon. Anti-inflammatory gene therapy improved the total antioxidative capacity. In comparison with the untreated group, bacterial gene therapy lowered the histological colitis score. Salmonella-mediated antioxidative and anti-inflammatory gene therapy alleviated colitis in mice. The effect seems to be mediated by increased antioxidative status. Further studies will show whether recombinant probiotics expressing therapeutic gene might be used for the therapy of inflammatory bowel diseases.

Oral administration of Parabacteroides distasonis antigens attenuates experimental murine colitis through modulation of immunity and microbiota composition

Commensal bacteria have been shown to modulate the host mucosal immune system. Here, we report that oral treatment of BALB/c mice with components from the commensal, Parabacteroides distasonis, significantly reduces the severity of intestinal inflammation in murine models of acute and chronic colitis induced by dextran sulphate sodium (DSS). The membranous fraction of P. distasonis (mPd) prevented DSS-induced increases in several proinflammatory cytokines, increased mPd-specific serum antibodies and stabilized the intestinal microbial ecology. The anti-colitic effect of oral mPd was not observed in severe combined immunodeficient mice and probably involved induction of specific antibody responses and stabilization of the intestinal microbiota. Our results suggest that specific bacterial components derived from the commensal bacterium, P. distasonis, may be useful in the development of new therapeutic strategies for chronic inflammatory disorders such as inflammatory bowel disease.

Guide to designing, conducting, publishing and communicating results of clinical studies involving probiotic applications in human participants

The heterogeneity of human clinical trials to assess the effectiveness of probiotics presents challenges regarding interpretation and comparison. Evidence obtained from clinical trials among a population with a disease or specific risk factors may not be generalizable to healthy individuals. The evaluation of interventions in healthy persons requires careful selection of outcomes due to the absence of health indicators and the low incidence of preventable conditions. Given the tremendous resources invested in such trials, development of consistent approaches to assessing the effectiveness of probiotics would be beneficial. Furthermore, the reporting, presentation and communication of results may also affect the validity of the scientific evidence obtained from a trial. This review outlines the challenges associated with the design, implementation, data analysis and interpretation of clinical trials in humans involving probiotics. Best practices related to their design are offered along with recommendations for enhanced collaboration to advance research in this emerging field.

Factors for bile tolerance in Lactococcus lactis: analysis by using plasmid variants

The factors of bile tolerance (as one among the fundamental characteristics of probiotic bacteria) were determined in lactococci by using plasmid variants. Bile tolerance of Lactococcus lactis wild-type (WT) strains 527 and N7 (determined by viability counts on bile-containing agar) was equivalent to the corresponding plasmid-free derivatives. In contrast, L. lactis WT strain DRC1 had lower bile tolerance than its plasmid-free derivative DRC1021. Plasmid pDR1-1B, extracted from strain DRC1, was introduced into strain DRC1021 by co-transformation with the vector plasmid pGKV21 as an indicator. Strain DRC121 (DRC1021 harboring pGKV21) had good bile tolerance as did strain DRC1021, while strain DRC13 (DRC1021 harboring both pDR1-1B and pGKV21) did not. Fatty acid (FA) composition was different between strains DRC121 and DRC13. The plasmid pDR1-1B or plasmid profile and FA composition are key factors for bile tolerance of strain DRC1, and therefore changing the plasmid profile might be a way of modulating bile tolerance in lactococci.

Molecular crosstalk of probiotic bacteria with the intestinal immune system: clinical relevance in the context of inflammatory bowel disease

It is current knowledge that the intestinal microbiota plays a major role in the development and maintenance of intestinal health. Intestinal epithelial cells (IEC) constitute the interface between the gut lumen and the innate and adaptive immune system. To maintain intestinal homeostasis, the organized and diffuse compartments of the gut-associated lymphoid tissue have to process the continuously varying information at the interface between the luminal side and the host. Dysregulated intestinal immune responses towards commensal bacteria are an important factor in the pathogenesis of inflammatory bowel diseases (IBD). In contrast to the colitogenic effects of enteric bacteria, clinical and experimental studies showed that specific probiotic strains are protective in the context of chronic intestinal inflammation. Although the molecular understanding of bacteria-host interaction is improving, the anti-inflammatory mechanisms induced by these probiotic bacteria are just starting to be unraveled. The present review is meant to summarize and discuss the clinical relevance of probiotics, but it also seeks to give an overview about currently known probiotic mechanisms in the context of chronic intestinal inflammation with a focus on IEC.

Estimation of the potential antitumor activity of microencapsulated Lactobacillus acidophilus yogurt formulation in the attenuation of tumorigenesis in Apc(Min/+) mice

There is a strong correlation between orally administered probiotics and suppression of the low-grade inflammation that can lead to restoration of normal local immune functions. We studied the potential immunomodulatory and antitumorigenic properties of microencapsulated probiotic bacterial cells in a yogurt formulation in Min mice carrying a germline APC mutation. Daily oral administration of microencapsulated Lactobacillus acidophilus bacterial cells in the yogurt formulation mice resulted in significant suppression of colon tumor incidence, tumor multiplicity, and reduced tumor size. Results show that oral administration of microencapsulated L. acidophilus contributed to the stabilization of animal body weight and decreased the release of bile acids. Histopathological analyses revealed fewer adenomas in treated versus untreated animals. Furthermore, treated animals exhibited fewer gastrointestinal intra-epithelial neoplasias with a lower grade of dysplasia in detected tumors. Results suggest that oral administration of microencapsulated probiotic L. acidophilus exerts anti-tumorous activity, which consequently leads to reduced tumor outcome.

Therapeutic effects of four strains of probiotics on experimental colitis in mice

AIM: To investigate the therapeutic effects of four strains of probiotics (E. feacalis, L. acidophilus, C. butyricum and B. adolescentis) on dextran sulphate sodium (DSS)-induced experimental colitis in Balb/c mice.

METHODS: Eighty Balb/c mice were randomly divided into 8 groups. Weight-loss, fecal character, fecal occult blood and hematochezia were recorded daily. Disease activity index (DAI) scores were also evaluated everyday. Length of colon was measured and histological scores were evaluated on the 13th day. Myeloperoxidase (MPO) activity was detected. Interleukin-1 (IL-1) and IL-4 expression was detected by ELISA and RT-PCR.

RESULTS: The four strains of probiotics relieved the inflammatory condition of DSS-induced experimental colitis in mice. Weight loss was slowed down in all probiotics-treated mice. Even weight gain was observed by the end of probiotics treatment. The DAI and histological scores of probiotics-treated mice were lower than those of mice in the control group (1.9 ± 0.2 vs 8.6 ± 0.4, P < 0.05 for E. faecalis). The length of colon of probiotics-treated mice was longer than that of mice in the control group (10.3 ± 0.34 vs 8.65 ± 0.77, P < 0.05 for E. faecalis). The four strains of probiotics decreased the MP activity and the IL-1 expression, but increased the IL-4 expression. E. faecalis had a better effect on DSS-induced experimental colitis in mice than the other three strains.

CONCLUSION: The four strains of probiotics have beneficial effects on experimental colitis in mice. E. faecalis has a better effect on DSS-induced experimental colitis in mice than the other three strains. Supplement of probiotics provides a new therapy for UC.

The innate immune receptor Nod1 protects the intestine from inflammation-induced tumorigenesis

There is growing evidence that the host innate immune system has a critical role in regulating carcinogenesis, but the specific receptors involved and the importance of their interaction with commensal bacteria need to be elucidated. Two major classes of innate immune receptors, the Toll-like receptors and Nod-like receptors, many of which are upstream of nuclear factor-kappaB, are involved in the detection of intestinal bacteria. The Toll-like receptors have been implicated in promoting colon tumorigenesis, but the role of Nod-like receptors in regulating tumorigenesis remains unclear. Using an established mouse model system of colitis-associated colon tumorigenesis, we show that Nod1 deficiency results in the increased development of both colitis-associated and Apc tumor suppressor-related colon tumors. In the absence of Nod1 signaling, there is a greater disruption of the intestinal epithelial cell barrier due to chemically induced injury as manifested by increased surface epithelial apoptosis early on during chemically induced colitis and increased intestinal permeability. The increased intestinal permeability is associated with enhanced inflammatory cytokine production and epithelial cell proliferation in Nod1-deficient mice as compared with wild-type mice. Depletion of the gut microbiota suppressed tumor development in Nod1-deficient mice, thus highlighting a link between the commensal bacteria within the intestine and the host innate immune Nod1 signaling pathway in the regulation inflammation-mediated colon cancer development.

Crohn's disease-associated Escherichia coli LF82 aggravates colitis in injured mouse colon via signaling by flagellin

BACKGROUND

Ileal lesions in Crohn's disease patients are colonized by pathogenic adherent-invasive Escherichia coli (AIEC) that harbor various virulence factors involved in adhesion to and invasion of intestinal epithelial cultured cells. We investigated in a mouse model of colonic inflammation the behavior of virulent AIEC reference bacteria LF82 compared to that of nonflagellated LF82 mutants.

METHODS

BALBc/J mice with intact or dextran sulfate sodium (DSS)-injured colon were orally challenged daily with 10(8) bacteria. The severity of colitis was assessed by determining disease activity index, colonic histological score, and myeoloperoxidase activity. Flagellin receptor and cytokine expression was measured by reverse-transcriptase polymerase chain reaction (RT-PCR) in colonic tissue.

RESULTS

In contrast to nonpathogenic E. coli, virulent LF82 bacteria exacerbated colitis in DSS-treated mice, substantially reducing survival rate, greatly lowering stool consistency, inducing marked weight loss and increased rectal bleeding, and significantly increasing erosive lesions and mucosal inflammation. Nonflagellated LF82 mutants behaved like nonpathogenic E. coli K-12. Interestingly, oral infection with LF82 virulent bacteria, but not with a nonvirulent LF82 mutant, induced a 7.0-fold increase in the levels of TLR5 and a 3.1-fold increase in those of ipaf mRNA, which encode respectively membrane and cytosolic receptors involved in the recognition of flagellin. Hence, a 5.6-fold increase in IL-1beta and a 5.3-fold increase in mRNA of IL-6 were observed in mice challenged with AIEC LF82 bacteria.

CONCLUSIONS

Crohn's disease-associated virulent AIEC LF82 bacteria, via expression of flagella, are able to potentiate an inflammatory mucosal immune response involving increased expression of TLR5 and IPAF flagellin receptors.

Clinical use of E. coli Nissle 1917 in inflammatory bowel disease

The probiotic Escherichia coli strain Nissle 1917 is in addition to some Lactobacilli sp. one of the best-studied probiotic strains. This particular E. coli strain was isolated in 1917 based on its potential to protect from presumably infectious gastroenteritis. Initial therapeutic success was noted in the management of gastrointestinal infectious disorders and infections affecting the urinary tract; the focus shifted later to chronic inflammatory conditions. The unique combination of fitness and survival factors to support intestinal survival, the lack of virulence, and obvious probiotic properties make this microorganism a safe and effective candidate in the treatment of chronic inflammatory bowel diseases. Three large clinical trials have assessed the potential in the maintenance of remission of ulcerative colitis and equivalence to standard 5-ASA medication was documented. This review aims to discuss important mechanisms of E. coli Nissle 1917 and will review the available literature regarding treatment of inflammatory bowel diseases.

Rationale for probiotic treatment strategies in inflammatory bowel disease

Chronic inflammatory bowel diseases (IBD), such as Crohn's disease and ulcerative colitis, are recurrent and aggressive inflammatory disorders that are most likely the result of an overly aggressive immune response to ubiquitous intestinal antigens in a genetically susceptible host. Despite decades of intense research, our knowledge of factors causing IBD remains incomplete and, therefore, conventional therapy to induce and maintain remission works in a symptomatic fashion, merely suppressing the immune response. Probiotic bacteria have long been known to confer health benefits, especially with regard to intestinal disorders. Although there is mounting evidence from in vitro and animal experiments supporting the use of probiotics in IBD, clinical trials have not provided definite evidence for the therapeutic effect of probiotic therapy in IBD to date. This is with the notable exception of pouchitis and the maintenance of remission in ulcerative colitis, whereas Crohn's disease and active ulcerative colitis do not seem amenable to probiotic intervention. The next 5 years will see more trials targeting specific clinical settings using tailor-made probiotic combinations, taking into account our increasing knowledge of individual probiotic properties and the diversity of these microorganisms.

Effects of monocolonization with Escherichia coli strains O6K13 and Nissle 1917 on the development of experimentally induced acute and chronic intestinal inflammation in germ-free immunocompetent and immunodeficient mice

Germ-free immunocompetent (BALB/c) and immunodeficient (SCID) mice were colonized either by E. coli O6K13 or by E. coli strain Nissle 1917 and intestinal inflammation was induced by administering 2.5% dextran sulfate sodium (DSS) in drinking water. Controls were germ-free mice which demonstrated only mild inflammatory changes after induction of an acute intestinal inflammation with DSS as compared with conventional mice in which acute colitis of the colon mucosa similar to human ulcerative colitis is elicited. In mice monocolonized with the nonpathogenic E. coli Nissle 1917 the inflammatory disease did not develop (damage grade 0) while animals monocolonized with uropathogenic E. coli O6K13 exhibited inflammatory changes similar to those elicited in conventionally reared mice (damage grade 3). In the chronic inflammation model, immunocompetent BALB/c mice monocolonized with E. coli Nissle 1917 showed no conspicuous inflammatory changes of the colon mucosa whereas those monocolonized with E. coli O6K13 developed colon inflammation associated with marked infiltration of inflammatory cells. In contrast to germ-free immunodeficient SCID mice that died after application of DSS, the colon mucosa of SCID mice monoassociated with E. coli Nissle 1917 exhibited only moderate inflammatory changes which were less pronounced than changes of colon mucosa of SCID mice monoassociated with E. coli O6K13.

Skin microbiota: a source of disease or defence?

Microbes found on the skin are usually regarded as pathogens, potential pathogens or innocuous symbiotic organisms. Advances in microbiology and immunology are revising our understanding of the molecular mechanisms of microbial virulence and the specific events involved in the host-microbe interaction. Current data contradict some historical classifications of cutaneous microbiota and suggest that these organisms may protect the host, defining them not as simple symbiotic microbes but rather as mutualistic. This review will summarize current information on bacterial skin flora including Staphylococcus, Corynebacterium, Propionibacterium, Streptococcus and Pseudomonas. Specifically, the review will discuss our current understanding of the cutaneous microbiota as well as shifting paradigms in the interpretation of the roles microbes play in skin health and disease.

Effect of oral application of a probioticE. coli strain on the intestinal microflora of children of allergic mothers during the first year of life

Influence of intestinal colonization by a probiotic E. coli strain on the incidence of bacterial pathogens in stool and allergic symptoms during the 1st year of life was monitored in 3 groups: colonized children of allergic mothers (AC; n = 52), noncolonized children of allergic mothers (AN; n = 50), children of nonallergic mothers (NC; n = 42). Colinfant vaccine was administered within 2 d after birth, 3 x a week over a period of 4 weeks. Stool samples were examined after 2 d and at the age of 3, 6 and 12 months. At 3 months E. coli was present in 90 %, at 12 months in 73 % of AC. Pathogens were significantly less frequent on day 3 and at 3 months in AC vs. AN (15 vs. 61 %, p < 0.001; 15 vs. 38 %, p < 0.01) and vs. NC (15 vs. 63 %, p < 0.001; 15 vs. 53 %, p < 0.001). AC exhibited lower incidence of Staphylococcus epidermidis than AN on day 3 (6 vs. 31 %, p < 0.001) and of Klebsiella strains on day 3 and at 3 months (4 vs. 20 %, p < 0.05; 5 vs. 24 %, p < 0.01). AC showed a lower incidence of Pseudomonas aeruginosa than NC on day 3 (6 vs. 31 %, p < 0.01) and Klebsiella spp. on day 3 and at 3 months (4 vs. 22 %, p < 0.05; 5 vs. 45 %, p < 0.001). No significant differences were recorded after 6 and 12 months. The incidence of allergies was 3 % in AC, 26 % in AN (p < 0.01), and 10 % in NC.