Probiotics in inflamatory bowel disease

Research on the Mechanism of HRP Relieving IPEC-J2 Cells Immunological Stress Based on Transcriptome Sequencing Analysis

Early weaning increased the economic benefits of piglets. However, early weaning damages the intestinal barrier of piglets and causes immunological stress. The mechanism by which Hippophae rhamnoides polysaccharide (HRP) alleviates lipopolysaccharide (LPS)-induced intestinal porcine epithelial cells (IPEC-J2) inflammatory damage was investigated using proteomics in our previous studies. In this study we employed RNA-sequencing (RNA-seq) to determine the level and function of differentially expressed genes (DEGs) and further explore the mechanism of the HRP anti-inflammatory and immune process. The differential expression analysis indicated that 3622, 1216, and 2100 DEGs in the IPEC-J2 cells were identified in C vs. L, L vs. H6-L, and C vs. H6-L, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis foundsix identified pathways related to the immune system. Additionally, we used the Science, Technology, Engineering, and Math (STEM) program to categorize the 3,134 DEGs that were differentially expressed in H2-L, H4-L and H6-L into eight possible expression profiles, in which 612 were clustered into two profiles. The accuracy and consistency of RNA-seq data were validated by the results of qRT-PCR of the nuclear factor of kappa light polypeptide gene enhancer in B-cells 2 (NFKB2), MAP kinase interacting serine/threonine kinase 2 (MKNK2), mitogen-activated protein kinase kinase 1 (MAP2K1), mitogen-activated protein kinase kinase kinase 8 (MAP3K8), Ras-related protein R-Ras (RRAS), TNF receptor-associated factor 1 (TRAF1), NF-kappa-B inhibitor alpha (NFKBIA), interleukin 8 (IL8), tumor necrosis factor, alpha-induced protein 3 (TNFAIP3), and transforming growth factor beta-1 (TGFB1). Transcriptome sequencing also indicated that HRP reduced the expression levels of related DEGs and inhibited the activation of the mitogen-activated protein kinase (MAPK)/nuclear factor kappa-B (NF-κB) signaling pathway. Our findings indicate that the application of HRP in piglet diets during the early weaning period can improve intestinal epithelial function and integrity, and relieve intestinal damage, and improve piglet health.

Improved functionality of Ligilactobacillus salivarius Li01 in alleviating colonic inflammation by layer-by-layer microencapsulation

The low viability during gastrointestinal transit and poor mucoadhesion considerably limits the effectiveness of Ligilactobacillus salivarius Li01 (Li01) in regulating gut microbiota and alleviating inflammatory bowel disease (IBD). In this study, a delivery system was designed through layer-by-layer (LbL) encapsulating a single Li01cell with chitosan and alginate. The layers were strengthened by cross-linking to form a firm and mucoadhesive shell (~10 nm thickness) covering the bacterial cell. The LbL Li01 displayed improved viability under simulated gastrointestinal conditions and mucoadhesive function. Almost no cells could be detected among the free Li01 after 2 h incubation in digestive fluids, while for LbL Li01, the total reduction was around 3 log CFU/mL and the viable number of cells remained above 6 log CFU/mL. Besides, a 5-fold increase in the value of rupture length and a two-fold increase in the number of peaks were found in the (bacteria-mucin) adhesion curves of LbL Li01, compared to those of free Li01. Oral administration with LbL Li01 on colitis mice facilitated intestinal barrier recovery and restoration of the gut microbiota. The improved functionality of Li01 by LbL encapsulation could increase the potential for the probiotic to be used in clinical applications to treat IBD; this should be explored in future studies.

Compatibility, Cytotoxicity, and Gastrointestinal Tenacity of Bacteriocin-Producing Bacteria Selected for a Consortium Probiotic Formulation to Be Used in Livestock Feed

Bacteriocin-producing Escherichia coli ICVB442, E. coli ICVB443, Enterococcus faecalis ICVB497, E. faecalis ICVB501, and Pediococcus pentosaceus ICVB491 strains were examined for their pathogenic risks and compatibility and hence suitability as consortium probiotic bacteria. Except for E. coli ICVB442, all were inclined to form biofilm. All were gelatinase-negative, sensitive to most of the antibiotics tested and not cytotoxic to porcine intestinal epithelial cells (IPEC-1) when tested at a multiplicity of infection (MOI) of 1. P. pentosaceus ICVB491 stood apart by inhibiting the other four strains. Both E. coli strains and E. faecalis ICVB497 strain were β-hemolytic. Survival in the TIM-1 dynamic model of the human digestive system was 139% for the tested E. coli ICVB443 strain, 46% for P. pentosaceus ICVB491, and 32% for the preferred E. faecalis ICVB501 strain. These three potential probiotics, which are bacteriocin-producing strains, will be considered for simultaneous use as consortium with synergistic interactions in vivo on animal model.

Enhancement of intestinal epithelial barrier function by Weissella confusa F213 and Lactobacillus rhamnosus FBB81 probiotic candidates in an in vitro model of hydrogen peroxide-induced inflammatory bowel disease

OBJECTIVE

Weissella confusa F213 (WCF213) and Lactobacillus rhamnosus FBB81 (LrFBB81) are two probiotic candidates isolated from humans in our previous study. Their functional activity on the mucosal barrier has not yet been adequately investigated. Therefore, the objective of this study was to investigate the effect of these strains on maintaining mucosal integrity in vitro. Caco-2 cell monolayers were pretreated with WCF213 and LrFBB81 before being exposed to hydrogen peroxide. The integrity of mucosal cells was evaluated by measuring the transepithelial resistance (TER), flux of FITC-labelled dextran, and ZO-1 protein distribution with the help of an immunofluorescence method.

RESULTS

WCF213 was found to significantly maintain the TER better than the control hydrogen peroxide-treated cells (p < 0.001), followed by the strain combination, and LrFBB81 alone (p < 0.05). The permeability of mucosa was also successfully maintained by the WCF213 strain. This was illustrated by the significant reduction in the flux of FITC-labelled dextran (p < 0.05), which was larger than that exhibited by the other groups. The ZO-1 distribution of strain-treated cells showed less disruption than hydrogen peroxide-treated cells, consistent with the TER and FITC experimental results. These findings indicate that WCF213 and LrFBB81 plays important roles in the maintenance of mucosal integrity in a strain-dependent manner.

Proteomic analysis reveals the molecular mechanism of Hippophae rhamnoides polysaccharide intervention in LPS-induced inflammation of IPEC-J2 cells in piglets

Early weaning can cause intestinal disorders and dysfunction in piglets, and may induce intestinal diseases. Hippophae rhamnoides polysaccharide (HRP) has anti-inflammatory and immune promotion function. However, few studies have explored the change of differentially protein expression by lipopolysaccharide (LPS)-induced porcine intestinal epithelial cell (IPEC-J2) after HRP pre-treatment. In this study, proteomic analysis was used to explore the essential proteins and immune-related pathways that can be regulated by LPS-induced IPEC-J2 cells after HRP pre-treatment. The results indicate that by searching the Sus scrofa database, a total of 18,768 proteins was identified. Among recognized proteins, there are 2052 (1720 up-regulated and 332 down-regulated), 358 (262 up-regulated and 96 down-regulated) and1532 (314 up-regulated and 1218 down-regulated) proteins expressed differently in C vs. L, C vs. H6-L and L vs. H6-L, respectively. The Cluster of Orthologous Groups (COG) analysis divided the identified proteins into 23 categories. Gene Ontology (GO) enrichment analysis revealed that cellular process, cell, cell part, organelle and binding were the most enriched pathways for differentially expressed proteins. KEGG enrichment analysis indicated that the top 20 pathways in the L-vs-H6-L group related to immunity were the Tight junction, MAPK signaling pathway, PI3K-Akt signaling pathway, rap1 signaling pathway, HIF-1 signaling pathway, Ras signaling pathway and Fc gamma R-mediated phagocytosis. Moreover, we also found 42 key proteins related to these immune pathways in this study. Additionally, western blotting analyses confirmed that LPS reduced the levels of claudin2 (CLDN2), insulin-like growth factor 2 (IGF2) and increased phosphorylated mitogen-activated protein kinase 7 (MAPK7), phosphorylated transcription factor p65 (RELA), phosphorylated nuclear factor NF-kappa-B p105 subunit (NF-κB1) and phosphorylated nuclear factor of kappa light polypeptide gene enhancer in B-cells 2 (NF-κB2). Pre-treatment with HRP increased the levels of CLDN2, IGF2 and reduced the levels of the phosphorylated MAPK7, phosphorylated RELA, phosphorylated NF-κB1 and phosphorylated NF-κB2 in cells. These results also showed that HRP alleviated LPS-induced inflammation in IPEC-J2 cells by inhibiting the MAPK/NF-κB signaling pathway and its related differentially expressed proteins.

Peroxisome Proliferator-Activated Receptors: Experimental Targeting for the Treatment of Inflammatory Bowel Diseases

The peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor proteins that promote ligand-dependent transcription of target genes that regulate energy production, lipid metabolism, and inflammation. The PPAR superfamily comprises three subtypes, PPARα, PPARγ, and PPARβ/δ, with differential tissue distributions. In addition to their different roles in the regulation of energy balance and carbohydrate and lipid metabolism, an emerging function of PPARs includes normal homeostasis of intestinal tissue. PPARα activation represses NF-κB signaling, which decreases the inflammatory cytokine production by different cell types, while PPARγ ligands can inhibit activation of macrophages and the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and Il-1β. In this regard, the anti-inflammatory responses induced by PPAR activation might restore physiopathological imbalances associated with inflammatory bowel diseases (IBD). Thus, PPARs and their ligands have important therapeutic potential. This review briefly discusses the roles of PPARs in the physiopathology and therapies of the most important IBDs, ulcerative colitis (UC), and Crohn's disease (CD), as well some new experimental compounds with PPAR activity as promising drugs for IBD treatment.

Pro-inflammatory potential of Escherichia coli strains K12 and Nissle 1917 in a murine model of acute ileitis

Non-pathogenic Escherichia coli (Ec) strains K12 (EcK12) and Nissle 1917 (EcN) are used for gene technology and probiotic treatment of intestinal inflammation, respectively. We investigated intestinal colonization and potential pro-inflammatory properties of EcK12, EcN, and commensal E. coli (EcCo) strains in Toxoplasma (T.) gondii-induced acute ileitis. Whereas gnotobiotic animals generated by quintuple antibiotic treatment were protected from ileitis, mice replenished with conventional microbiota suffered from small intestinal necrosis 7 days post-T. gondii infection (p.i.). Irrespective of the Ec strain, recolonized mice revealed mild to moderate histopathological changes in their ileal mucosa. Upon stable recolonization with EcK12, EcN, or EcCo, development of inflammation was accompanied by pro-inflammatory responses at day 7 p.i., including increased ileal T lymphocyte and apoptotic cell numbers compared to T. gondii-infected gnotobiotic controls. Strikingly, either Ec strain was capable to translocate to extra-intestinal locations, such as MLN, spleen, and liver. Taken together, Ec strains used in gene technology and probiotic treatment are able to exert inflammatory responses in a murine model of small intestinal inflammation. In conclusion, the therapeutic use of Ec strains in patients with broad-spectrum antibiotic treatment and/or intestinal inflammation should be considered with caution.

Pistacia lentiscus resin regulates intestinal damage and inflammation in trinitrobenzene sulfonic acid-induced colitis

Mastic (Pistacia lentiscus) of the Anacardiaceae family has exhibited anti-inflammatory and antioxidant properties in patients with Crohn's disease. This study was based on the hypothesis that mastic inhibits intestinal damage in inflammatory bowel disease, regulating inflammation and oxidative stress in intestinal epithelium. Four different dosages of P. lentiscus powder in the form of powder were administered orally to trinitrobenzene sulfonic acid-induced colitic rats. Eighty-four male Wistar rats were randomly assigned to seven groups: A, control; B, colitic; C-F, colitic rats daily supplemented with P. lentiscus powder at (C) 50 mg/kg, (D) 100 mg/kg, (E) 200 mg/kg, and (F) 300 mg/kg of body weight; and G, colitic rats treated daily with cortisone (25 μg/kg of body weight). Colonic damage was assessed microscopically. The cytokines tumor necrosis factor-α, intercellular adhesion molecule-1 (ICAM-1), interleukin (IL)-6, IL-8, and IL-10 and malonaldehyde were measured in colonic specimens. Results were expressed as mean ± SE values. Histological amelioration of colitis (P≤.001) and significant differences in colonic indices occurred after 3 days of treatment. Daily administration of 100 mg of P. lentiscus powder/kg of body weight decreased all inflammatory cytokines (P≤.05), whereas 50 mg of P. lentiscus powder/kg of body weight and cortisone treatment reduced only ICAM-1 (P≤.05 and P≤.01, respectively). Malonaldehyde was significantly suppressed in all treated groups (P≤.01). IL-10 remained unchanged. Cytokines and malonaldehyde remained unaltered after 6 days of treatment. Thus P. lentiscus powder could possibly have a therapeutic role in Crohn's disease, regulating oxidant/antioxidant balance and modulating inflammation.

E durans strain M4-5 isolated from human colonic flora attenuates intestinal inflammation

PURPOSE

The aim of this study was to evaluate in vitro and in vivo effects of a unique high-butyrate-producing bacterial strain from human colonic flora, Enterococcus durans, in prevention and treatment of intestinal inflammation.

METHODS

A compartmentalized Caco-2/leukocyte coculture model was used to examine the in vitro effects of E durans and its metabolite butyrate on basal and Escherichia coli-stimulated secretion of proinflammatory immune factors (IL-8, IL-6, and TNF-α) and the anti-inflammatory cytokine IL-10. A murine model of dextran sodium sulfate-induced colitis was used to examine in vivo effects of prevention and therapy with E durans on clinical, biochemical, and histologic parameters of inflammation.

RESULTS

In the coculture model, treatment with E durans and with butyrate reduced basal as well as E coli stimulated secretion of IL-8, IL-6, and TNF-α and increased secretion of IL-10. In the in vivo murine model, preventive administration of E durans significantly ameliorated clinical disease activity index (weight loss, fecal bleeding, and stool consistency), reduced myeloperoxidase concentration in colon tissue extracts, improved histologic scores of colonic inflammation, and inhibited colonic transcription of proinflammatory immune factors. The effect of therapeutic treatment alone on these parameters was more moderate but still significant.

CONCLUSIONS

We conclude that E durans strain M4 to 5 and its metabolic product butyrate induce significant anti-inflammatory effects, mediated by regulation of pro- and anti-inflammatory immune factors as well as preservation of intestine epithelial integrity, suggesting that this novel anti-inflammatory bacterium may be preferentially a useful prophylactic treatment to avoid inflammatory bowel disease.

The role of bacteria in the pathogenesis of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) have features that suggest bacterial involvement, and all genetic models of inflammatory bowel disease (IBD) require the presence of commensal bacteria. CD is associated with innate immune response genes such as NOD2/CARD15 and the autophagy genes ATG16L1 and IRGM. However, IBD responds to immunosuppression, suggesting that any bacteria involved are not acting as conventional pathogens. Molecular techniques are rapidly advancing our knowledge of the gut microbiota. In CD there is reduced diversity, and notably a reduction in the probiotic Faecalibacterium prausnitzii, the presence of which in the terminal ileum is associated with a reduced risk of recurrence following surgery. There is also a consistent increase in mucosa-associated Escherichia coli with an "adherent and invasive" phenotype, which allows them to replicate inside macrophages and induce granulomas. Speculation that CD could be caused by the Mycobacterium avium subspecies paratuberculosis (MAP) continues. The response to antitumor necrosis factor treatments suggests that, if relevant at all, MAP is not acting as a conventional pathogen. However, there is increased colonization by MAP in CD, and there is evidence that it could have an indirect effect mediated by the suppression of macrophage function. UC relapse is frequently associated with infection by pathogens, but there is less evidence for involvement of a specific bacterial species. Poor barrier integrity followed by an inflammatory reaction to bacterial components, with chronicity maintained by an autoimmune process, seems a plausible pathogenic model. Bacterial theories of pathogenesis are now becoming testable by targeted therapeutic interventions.

What is the evidence for the use of probiotics in the treatment of inflammatory bowel disease?

AIMS AND OBJECTIVES

The purpose of this article is to investigate the use of probiotics in the treatment of inflammatory bowel disease.

BACKGROUND

Probiotics have been successfully used to treat various acute illnesses such as Clostridium difficile infection, rotovirus diarrhoea and traveller's diarrhoea. Recently, some studies have reported success with probiotics in the treatment of chronic intestinal diseases such as inflammatory bowel disease.

DESIGN

Literature review.

METHODS

A literature search was performed to include studies on Bifidobacteria-fermented milk, Escherichia coli, Lactobacillus, Saccharomyces boulardii, VSL #3 and probiotic use. Results of the literature are analysed, and a discussion is made regarding evaluation of the literature and implications for care.

RESULTS

The majority of probiotics studied have proven to have beneficial effects in the treatment of inflammatory bowel disease, especially when taken as a dietary adjunctive to standard treatment. All probiotics studied, with the exception of Lactobacillus GG and LA1, demonstrated positive results.

CONCLUSIONS

The increasing use of probiotics combined with the insufficient knowledge regarding the use of probiotics in treating inflammatory bowel disease requires that future multilevel, multicentre large randomised control trials be conducted to understand better the specific measures and effectiveness of such treatment.

RELEVANCE TO CLINICAL PRACTICE

Given that few clinical trials exist to study the potential role of probiotics in the treatment of inflammatory bowel disease, it is imperative that healthcare providers become knowledgeable about the use of probiotics and their effects on inflammatory bowel disease.

Understanding the mechanisms by which probiotics inhibit gastrointestinal pathogens

In recent years, there has been a growing interest in the use of probiotic bacteria for the maintenance of general gastrointestinal health and the prevention or treatment of intestinal infections. Whilst probiotics are documented to reduce or prevent specific infectious diseases of the GI tract, the mechanistic basis of this effect remains unclear. It is likely that diverse modes-of-action contribute to inhibition of pathogens in the gut environment and proposed mechanisms include (i) direct antimicrobial activity through production of bacteriocins or inhibitors of virulence gene expression; (ii) competitive exclusion by competition for binding sites or stimulation of epithelial barrier function; (iii) stimulation of immune responses via increases of sIgA and anti-inflammatory cytokines and regulation of proinflammatory cytokines; and (iv) inhibition of virulence gene or protein expression in gastrointestinal pathogens. In this review, we discuss the modes of action by which probiotic bacteria may reduce gastrointestinal infections, and highlight some recent research which demonstrates the mechanistic basis of probiotic cause and effect.

Interactions of the intestinal epithelium with the pathogen and the indigenous microbiota: a three-way crosstalk

The mucosal surfaces of the gastrointestinal tract harbor a vast number of commensal microbiota that have coevolved with the host, and in addition display one of the most complex relationships with the host. This relationship affects several important aspects of the biology of the host including the synthesis of nutrients, protection against infection, and the development of the immune system. On the other hand, despite the existence of several lines of mucosal defense mechanisms, pathogenic organisms such as Shigella and Salmonella have evolved sophisticated virulence strategies for breaching these barriers. The constant challenge from these pathogens and the attempts by the host to counter them set up a dynamic equilibrium of cellular and molecular crosstalk. Even slight perturbations in this equilibrium may be detrimental to the host leading to severe bacterial infection or even autoimmune diseases like inflammatory bowel disease. Several experimental model systems, including germ-free mice and antibiotic-treated mice, have been used by various researchers to study this complex relationship. Although it is only the beginning, it promises to be an exciting era in the study of these host-microbe relationships.

A meta-analysis on the efficacy of probiotics for maintenance of remission and prevention of clinical and endoscopic relapse in Crohn's disease

OBJECTIVE

To evaluate whether probiotics maintain remission in patients with Crohn's disease (CD).

DESIGN

A meta-analysis of controlled clinical trials.

METHODS

PUBMED and Cochrane Central Register of Controlled Trials were searched for clinical trial studies investigated the efficacy of probiotics for the maintenance of remission in Crohn's disease. Clinical relapse and endoscopic relapse were the key outcomes of interest. Data were searched within the time period of 1966 through May 2007.

RESULT

Eight randomized placebo-controlled clinical trials met our criteria and were included in the analysis. Seven determined clinical relapse and three evaluated endoscopic relapse among patients with CD received probiotics for maintenance of remission. Pooling of seven trials for the outcome of clinical relapse yielded an odds ratio of 0.92 (95% confidence interval of 0.52-1.62, P = 0.8853), a nonsignificant odds ratio. The odds ratio for three studies for the outcome of endoscopic relapse was 0.97 (95% confidence interval of 0.54-1.78, P = 0.93), a nonsignificant odds ratio.

CONCLUSION

This meta-analysis fails to demonstrate the efficacy of probiotics in maintaining remission and preventing clinical and endoscopic recurrence in CD. It is suggested to use probiotic preparations containing a mixture of lactobacillus with E. coli or Saccharomyces.

High-dose probiotics for the treatment of active pouchitis

PURPOSE

Pouchitis is the major long-term complication after ileal-pouch anal anastomosis for ulcerative colitis. Broad-spectrum antibiotics are the mainstay of treatment in this condition. Recently, we have shown the efficacy of a highly concentrated probiotic preparation (VSL#3, 900 billions/sachet lyophilized viable bacteria) in preventing relapses of chronic pouchitis and in preventing pouchitis onset. This study was designed to evaluate the efficacy of high-dose VSL#3 in the treatment of mildly active pouchitis.

METHODS

Twenty-three consecutive patients with mild pouchitis, defined as a score of between 7 and 12 in the Pouchitis Disease Activity Index, which includes clinical, endoscopic, and histological criteria, were treated with VSL#3, 2 sachets b.i.d. (3,600 billion bacteria/day) for four weeks. Symptomatic, endoscopic, and histologic evaluations were undertaken before and after treatment according to Pouchitis Disease Activity Index. Remission was defined as a combination of a Pouchitis Disease Activity Index clinical score of <or=2, endoscopic score of <or=1, and total Pouchitis Disease Activity Index score of <or=4. Patients in remission after treatment were treated with VSL#3, 1 sachet b.i.d. (1,800 billion bacteria), as maintenance treatment for six months. The quality of life was assessed with the Inflammatory Bowel Disease Questionnaire.

RESULTS

Sixteen of 23 patients (69 percent) were in remission after treatment. The median total Pouchitis Disease Activity Index scores before and after therapy were 10 (range, 9-12) and 4 (range, 2-11), respectively (P < 0.01). The median Inflammatory Bowel Disease Questionnaire score also significantly improved from 110 (range, 90-140) to 200 (range, 95-220; P < 0.001). All 16 patients who went into remission maintained remission during maintenance treatment. Only one patient experienced a transient bloating at the beginning of treatment.

CONCLUSIONS

High doses of the probiotic VSL#3 are effective in the treatment of mild pouchitis. Further controlled studies are warranted.

Lactobacillus casei prevents the development of dextran sulphate sodium-induced colitis in Toll-like receptor 4 mutant mice

Probiotics, defined as live or attenuated bacteria or bacterial products, confer a significant health benefit to the host. Recently, they have been shown to be useful in the treatment of chronic inflammatory bowel disease and infectious colitis. In this study, we investigated the effect of probiotics on the development of experimental colitis using Toll-like receptor 4 (TLR-4) mutant (lps-/lps-) mice. TLR-4(lps-/lps-) and wild-type (WT) mice were given 2.5% dextran sulphate sodium (DSS) in drinking water to induce colitis with or without Lactobacillus casei pretreatment. Clinical and histological activity of DSS-colitis was attenuated markedly both in TLR-4(lps-/lps-) and WT mice pretreated with L. casei. Interestingly, histological activity was less severe in TLR-4(lps-/lps-) mice than in WT mice. The levels of myeloperoxidase activity and interleukin (IL)-12p40 were attenuated in pretreated TLR-4(lps-/lps-) mice after DSS administration. By contrast, transforming growth factor (TGF)-beta and IL-10 mRNA and protein expressions were increased markedly in pretreated TLR-4(lps-/lps-) mice. The current results suggest that L. casei has a preventive effect in the development of acute DSS-induced colitis and its action depends largely upon TLR-4 status. L. casei modulates the expression of inflammatory cytokines and down-regulates neutrophilic infiltration in the case of incomplete TLR-4 complex signalling.

Sensitivity to Escherichia coli Nissle 1917 in mice is dependent on environment and genetic background

Escherichia coli Nissle 1917 (EcN) is a well-characterized probiotic bacterium. Although genomic comparisons of EcN with the uropathogenic E. coli strain CFT073 revealed high degrees of similarity, EcN is generally considered a non-pathogenic organism. However, as recent evidence suggests that EcN is capable of inducing inflammatory responses in host intestinal epithelial cells, we aimed to investigate potential pathogenic properties of EcN in an in vivo model using various germ-free (GF) mouse strains. With the exception of C3H/HeJZtm mice, which carry a defective toll-like receptor (TLR)4-allele, no lesions were obvious in mice of different strains orally inoculated with EcN for 1 week, although organ cultures (blood, lung, mesenteric lymph node, pancreas, spleen, liver and kidney) tested positive to various degrees. C3H/HeJZtm mice inoculated with EcN became clinically ill and the majority died or had to be euthanized. Organs of all gnotobiotic C3H/HeJZtm mice were positive for EcN by culture; major histological findings were moderate to severe pyogranulomatous serositis, typhlitis and pancreatitis. Histological findings were corroborated by highly elevated tumour necrosis factor (TNF) serum levels. Lesions were not detected in specified pathogen free maintained C3H/HeJZtm mice, GF C3H/HeJ mice lacking the interleukin-10 gene, or GF C3H/HeJZtm mice that were inoculated with E. coli K12 strain MG1655 as a control. In addition, mild histological lesions were detected in Ztm:NMRI mice 3 months after oral inoculation with EcN. This study shows that EcN is capable of displaying a virulent phenotype in GF C3H/HeJZtm mice. Whether this phenotype is linked to the bacterium's probiotic nature should be the focus of further studies.

[Probiotics and prebiotics in inflammatory bowel disease]

Multiple studies of the immune system in patients with inflammatory bowel disease (IBD) have demonstrated the presence of altered intestinal mucosal immunity, probably genetically determined, giving rise to increased immunoreactivity against elements of the commensal flora. The basic strategy in the treatment of IBD is aimed at suppressing inflammatory responses. With the exception of studies of antibiotic therapy, little attention has been paid to modifying intestinal flora. Modification of intestinal flora through probiotics provides the possibility of acting microbiologically as well as immunologically. From the physiopathological point of view, the use of probiotics in IBD is a good therapeutic alternative. However, at present, studies with probiotics have only yielded positive results in highly specific situations. Secondary physiopathological data from clinical trials suggest a beneficial effect. However, this effect should be confirmed either in studies with a larger number of patients or by applying strategies that more effectively modify the composition of intestinal flora.

Bacterial and fungal microbiota in relation to probiotic therapy (VSL#3) in pouchitis

BACKGROUND

The intestinal microbiota plays a critical role in the pathophysiology of pouchitis, a major complication after ileal pouch anal anastomosis in patients with ulcerative colitis. Recently, controlled trials have demonstrated that probiotics are effective in maintenance of remission in pouchitis patients. However, the mechanism by which therapy with probiotics works remains elusive. This study explores the role of the bacterial and fungal flora in a controlled trial for maintenance of remission in pouchitis patients with the probiotic VSL#3 compound.

METHODS

The mucosa associated pouch microbiota was investigated before and after therapy with VSL#3 by analysis of endoscopic biopsies using ribosomal DNA/RNA based community fingerprint analysis, clone libraries, real time polymerase chain reaction (PCR), and fluorescence in situ hybridisation. Patients were recruited from a placebo controlled remission maintenance trial with VSL#3.

RESULTS

Patients who developed pouchitis while treated with placebo had low bacterial and high fungal diversity. Bacterial diversity was increased and fungal diversity was reduced in patients in remission maintained with VSL#3 (p = 0.001). Real time PCR experiments demonstrated that VSL#3 increased the total number of bacterial cells (p = 0.002) and modified the spectrum of bacteria towards anaerobic species. Taxa specific clone libraries for Lactobacilli and Bifidobacteria showed that the richness and spectrum of these bacteria were altered under probiotic therapy.

CONCLUSIONS

Probiotic therapy with VSL#3 increases the total number of intestinal bacterial cells as well as the richness and diversity of the bacterial microbiota, especially the anaerobic flora. The diversity of the fungal flora is repressed. Restoration of the integrity of a "protective" intestinal mucosa related microbiota could therefore be a potential mechanism of probiotic bacteria in inflammatory barrier diseases of the lower gastrointestinal tract.

Environment as a Critical Factor for the Pathogenesis and Outcome of Gastrointestinal Disease: Experimental and Human Inflammatory Bowel Disease and Helicobacter-Induced Gastritis

Environmental factors play an important role in the manifestation, course, and prognosis of diseases of the gastrointestinal tract such as inflammatory bowel disease (IBD) and Helicobacter pylori-induced gastritis. These two disease complexes were chosen for a discussion of the contribution of environmental factors to the disease outcome in humans and animal models. Dissecting complex diseases like IBD and Helicobacter-induced gastritis has shown that the outcome of disease depends on the allelic constellation of a host and the microbial and physical environments. Host alleles predisposing to a disease in one genomic and/or environmental milieu may not be deleterious in other constellations; on the other hand, microbes can have different effects in different hosts and under different environmental conditions. The impact of the complex interaction between host genetics and environmental factors, particularly microflora, also underlines the importance of a defined genetic background and defined environments in animal studies and is indicative of the difficulties in analyzing complex diseases in humans.

Lactobacillus casei DN-114 001 inhibits the ability of adherent-invasive Escherichia coli isolated from Crohn's disease patients to adhere to and to invade intestinal epithelial cells

Ileal lesions in 36.4% of patients with Crohn's disease are colonized by pathogenic adherent-invasive Escherichia coli. The aim of this study was to determine the in vitro inhibitory effects of the probiotic strain, Lactobacillus casei DN-114 001, on adhesion to and invasion of human intestinal epithelial cells by adherent-invasive E. coli isolated from Crohn's disease patients. The experiments were performed with undifferentiated Intestine-407 cells and with undifferentiated or differentiated Caco-2 intestinal epithelial cells. Bacterial adhesion to and invasion of intestinal epithelial cells were assessed by counting CFU. The inhibitory effects of L. casei were determined after coincubation with adherent-invasive E. coli or after preincubation of intestinal cells with L. casei prior to infection with adherent-invasive E. coli. Inhibitory effects of L. casei on adherent-invasive E. coli adhesion to differentiated and undifferentiated intestinal epithelial cells reached 75% to 84% in coincubation and 43% to 62% in preincubation experiments, according to the cell lines used. Addition of L. casei culture supernatant to the incubation medium increased L. casei adhesion to intestinal epithelial cells and enhanced the inhibitory effects of L. casei. The inhibitory effects on E. coli invasion paralleled those on adhesion. This effect was not due to a bactericidal effect on adherent-invasive E. coli or to a cytotoxic effect on epithelial intestinal cells. As Lactobacillus casei DN-114 001 strongly inhibits interaction of adherent-invasive E. coli with intestinal epithelial cells, this finding suggests that the probiotic strain could be of therapeutic value in Crohn's disease.

A synthetic TLR4 antagonist has anti-inflammatory effects in two murine models of inflammatory bowel disease

Current evidence indicates that the chronic inflammation observed in the intestines of patients with inflammatory bowel disease is due to an aberrant immune response to enteric flora. We have developed a lipid A-mimetic, CRX-526, which has antagonistic activity for TLR4 and can block the interaction of LPS with the immune system. CRX-526 can prevent the expression of proinflammatory genes stimulated by LPS in vitro. This antagonist activity of CRX-526 is directly related to its structure, particularly secondary fatty acyl chain length. In vivo, CRX-526 treatment blocks the ability of LPS to induce TNF-alpha release. Importantly, treatment with CRX-526 inhibits the development of moderate-to-severe disease in two mouse models of colonic inflammation: the dextran sodium sulfate model and multidrug resistance gene 1a-deficient mice. By blocking the interaction between enteric bacteria and the innate immune system, CRX-526 may be an effective therapeutic molecule for inflammatory bowel disease.

Probiotics: do they have a role in oral medicine and dentistry?

This review describes current knowledge on probiotic bacteriotherapy from the oral health perspective. Recent experimental studies and results from randomized controlled trials have shown that certain gut bacteria, in particular species of Lactobacillus and Bifidobacterium, may exert beneficial effects in the oral cavity by inhibiting cariogenic streptococci and Candida sp. Probiotics have been successfully used to control gastro-intestinal diseases. They also appear to alleviate symptoms of allergy and diseases with immunological pathology. The mechanisms of probiotic action appear to link with colonization resistance and immune modulation. Lactic acid bacteria can produce different antimicrobial components such as organic acids, hydrogen peroxide, carbon peroxide, diacetyl, low molecular weight antimicrobial substances, bacteriocins, and adhesion inhibitors, which also affect oral microflora. However, data is still sparse on the probiotic action in the oral cavity. More information is needed on the colonization of probiotics in the mouth and their possible effect on and within oral biofilms. There is every reason to believe that the putative probiotic mechanisms of action are the same in the mouth as they are in other parts of the gastrointestinal tract. Because of the increasing global problem with antimicrobial drug resistance, the concept of probiotic therapy is interesting and pertinent, and merits further research in the fields of oral medicine and dentistry.

Escherichia coli Nissle 1917 distinctively modulates T-cell cycling and expansion via toll-like receptor 2 signaling

Although the probiotic Escherichia coli strain Nissle 1917 has been proven to be efficacious for the treatment of inflammatory bowel diseases, the underlying mechanisms of action still remain elusive. The aim of the present study was to analyze the effects of E. coli Nissle 1917 on cell cycling and apoptosis of peripheral blood and lamina propria T cells (PBT and LPT, respectively). Anti-CD3-stimulated PBT and LPT were treated with E. coli Nissle 1917-conditioned medium (E. coli Nissle 1917-CM) or heat-inactivated E. coli Nissle 1917. Cyclin B1, DNA content, and caspase 3 expression were measured by flow cytometry to assess cell cycle kinetics and apoptosis. Protein levels of several cell cycle and apoptosis modulators were determined by immunoblotting, and cytokine profiles were determined by cytometric bead array. E. coli Nissle 1917-CM inhibits cell cycling and expansion of peripheral blood but not mucosal T cells. Bacterial lipoproteins mimicked the effect of E. coli Nissle 1917-CM; in contrast, heat-inactivated E. coli Nissle 1917, lipopolysaccharide, or CpG DNA did not alter PBT cell cycling. E. coli Nissle 1917-CM decreased cyclin D2, B1, and retinoblastoma protein expression, contributing to the reduction of T-cell proliferation. E. coli Nissle 1917 significantly inhibited the expression of interleukin-2 (IL-2), tumor necrosis factor alpha, and gamma interferon but increased IL-10 production in PBT. Using Toll-like receptor 2 (TLR-2) knockout mice, we further demonstrate that the inhibition of PBT proliferation by E. coli Nissle 1917-CM is TLR-2 dependent. The differential reaction of circulating and tissue-bound T cells towards E. coli Nissle 1917 may explain the beneficial effect of E. coli Nissle 1917 in intestinal inflammation. E. coli Nissle 1917 may downregulate the expansion of newly recruited T cells into the mucosa and limit intestinal inflammation, while already activated tissue-bound T cells may eliminate deleterious antigens in order to maintain immunological homeostasis.

Escherichia coli Nissle 1917 distinctively modulates T-cell cycling and expansion via toll-like receptor 2 signaling

Although the probiotic Escherichia coli strain Nissle 1917 has been proven to be efficacious for the treatment of inflammatory bowel diseases, the underlying mechanisms of action still remain elusive. The aim of the present study was to analyze the effects of E. coli Nissle 1917 on cell cycling and apoptosis of peripheral blood and lamina propria T cells (PBT and LPT, respectively). Anti-CD3-stimulated PBT and LPT were treated with E. coli Nissle 1917-conditioned medium (E. coli Nissle 1917-CM) or heat-inactivated E. coli Nissle 1917. Cyclin B1, DNA content, and caspase 3 expression were measured by flow cytometry to assess cell cycle kinetics and apoptosis. Protein levels of several cell cycle and apoptosis modulators were determined by immunoblotting, and cytokine profiles were determined by cytometric bead array. E. coli Nissle 1917-CM inhibits cell cycling and expansion of peripheral blood but not mucosal T cells. Bacterial lipoproteins mimicked the effect of E. coli Nissle 1917-CM; in contrast, heat-inactivated E. coli Nissle 1917, lipopolysaccharide, or CpG DNA did not alter PBT cell cycling. E. coli Nissle 1917-CM decreased cyclin D2, B1, and retinoblastoma protein expression, contributing to the reduction of T-cell proliferation. E. coli Nissle 1917 significantly inhibited the expression of interleukin-2 (IL-2), tumor necrosis factor alpha, and gamma interferon but increased IL-10 production in PBT. Using Toll-like receptor 2 (TLR-2) knockout mice, we further demonstrate that the inhibition of PBT proliferation by E. coli Nissle 1917-CM is TLR-2 dependent. The differential reaction of circulating and tissue-bound T cells towards E. coli Nissle 1917 may explain the beneficial effect of E. coli Nissle 1917 in intestinal inflammation. E. coli Nissle 1917 may downregulate the expansion of newly recruited T cells into the mucosa and limit intestinal inflammation, while already activated tissue-bound T cells may eliminate deleterious antigens in order to maintain immunological homeostasis.

Transcriptional regulation through RfaH contributes to intestinal colonization byEscherichia coli

The Escherichia coli regulatory protein RfaH contributes to efficient colonization of the mouse gut. Extraintestinal pathogenic (ExPEC) as well as non-pathogenic probiotic E. coli strains rapidly outcompeted their isogenic rfaH mutants following oral mixed infections. LPS-core and O-antigen side-chain as well as capsular polysaccharide synthesis are among the E. coli virulence factors affected by RfaH. In respect of colonization, deep-rough LPS mutants (waaG) but not capsular (kps) mutants were shown to behave similarly to rfaH mutants. Furthermore, alteration in the length of O-antigen side-chains did not modify colonization ability either indicating that it was the regulatory effect of RfaH on LPS-core synthesis, which affected intestinal colonization. Loss of RfaH did not significantly influence adhesion of bacteria to cultured colon epithelial cells. Increased susceptibility of rfaH mutants to bile salts, on the other hand, suggested that impaired in vivo survival could be responsible for the reduced colonization capacity.

Antagonistic activities of lactobacilli and bifidobacteria against microbial pathogens

The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1 x 10(14) colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.

High prevalence of adherent-invasive Escherichia coli associated with ileal mucosa in Crohn's disease

BACKGROUND & AIMS

Adherent-invasive Escherichia coli (AIEC) pathovar has been identified in the intestinal mucosa of patients with Crohn's disease (CD). AIEC reference strain LF82 is able to adhere to intestinal epithelial cells, to invade epithelial cells via a mechanism involving actin polymerization and microtubules, and to survive and replicate within macrophages. This study was performed to assess the prevalence of AIEC associated with intestinal mucosa of patients with CD, ulcerative colitis (UC), and of controls.

METHODS

A search for E. coli strains was performed with ileal specimens of 63 patients with CD and 16 controls without inflammatory bowel disease (IBD), and with colonic specimens of 27 patients with CD, 8 patients with UC, and 102 controls. The abilities of E. coli strains to invade epithelial cells and to survive and replicate within macrophages were assessed using the gentamicin protection assay. Bacterial uptake by epithelial cells was analyzed using cytoskeletal inhibitors. Bacterial adhesion was quantified with Caco-2 and Intestine-407 cells. The presence of known E. coli virulence genes was assessed by polymerase chain reaction and DNA hybridization.

RESULTS

In ileal specimens, AIEC strains were found in 21.7% of CD chronic lesions vs. in 6.2% of controls. In neoterminal ileal specimens, AIEC strains were found in 36.4% of CD early lesions (P = 0.034 vs. controls) and 22.2% of healthy mucosa of CD patients. In colonic specimens, AIEC strains were found in 3.7% of CD patients, 0% of UC patients, and 1.9% of controls.

CONCLUSIONS

AIEC strains are associated specifically with ileal mucosa in CD.

Probiotics and inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterised by a chronic dysregulation of the inflammatory response in the gastrointestinal tract. While the pathogenesis is unclear, studies have demonstrated that the gastrointestinal tracts of patients with IBD are populated with increased levels of adherent and pathogenic bacteria. This evidence, combined with growing data accumulated from genetic studies as well as animal models of IBD, indicates that an aberrant response to altered enteric flora plays a significant role in the disease process. Current therapies for IBD have been directed towards the development of anti-inflammatory agents and immunomodulators to attenuate the inflammatory response in the gastrointestinal tract. Antibiotics are also partially effective in the treatment of IBD, presumably by altering the bowel flora. However, it is clear from clinical trials that immunomodulators and antibiotics are not effective in a large proportion of patients with IBD and other therapeutic alternatives need to be pursued. Probiotics are microbial supplements capable of recolonising the bowel with non-pathogenic strains of bacteria or yeast. Probiotics have long been shown to be beneficial in both infectious and non-infectious digestive disorders. Growing evidence indicates that probiotics may be effective in the treatment of specific clinical IBD conditions. This article addresses the current evidence for the role of enteric flora in the pathogenesis of IBD and the clinical evidence supporting the use of probiotics in specific clinical IBD conditions.

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The effect of Lactobacillus plantarum 299v on the bacterial composition and metabolic activity in faeces of healthy volunteers: a placebo-controlled study on the onset and duration of effects

AIM

To study the onset and duration of a possible effect of a fermented oatmeal drink containing Lactobacillus plantarum 299v on the composition of the faecal flora of healthy volunteers in a placebo-controlled, double-blind study.

METHODS

Twenty-two participants consumed a fermented oatmeal drink with or without L. plantarum 299v for 4 weeks. Faecal samples were collected weekly: two samples before, four during and four after the consumption of the drink. Several bacterial species were counted and enzyme activities, short-chain fatty acid concentrations, endotoxin concentration and pH were determined. L. plantarum 299v was identified using randomly amplified polymorphic DNA.

RESULTS

In contrast with the placebo group, median lactobacilli counts increased significantly from 4.2 (3.4-6.3) to 8.2 (7.3-8.5) log colony-forming units/gram faeces (P = 0.005) after 1 week of consumption of L. plantarum 299v, thereafter remaining stable during the treatment period. One week after cessation, a significant decrease in lactobacilli [to 4.4 (2.2-6.5) log colony-forming units/gram faeces] was observed (P = 0.003). These lactobacilli were identified as L. plantarum 299v. All other bacterial counts, enzyme activities, short-chain fatty acid concentrations, endotoxin concentration and pH remained unchanged.

CONCLUSIONS

L. plantarum 299v significantly increased the number of lactobacilli in the faecal flora within 1 week, and this effect disappeared within 1 week after cessation of intake. No other changes in bacterial counts and metabolic products were observed.

Prophylaxis of pouchitis onset with probiotic therapy: a double-blind, placebo-controlled trial

BACKGROUND & AIMS

We have recently documented the efficacy of a highly concentrated probiotic preparation (VSL#3) in the prevention of flare-up in patients with chronic pouchitis. The aim of this study was to compare probiotic therapy with VSL#3 versus placebo in the ability to prevent the onset of acute pouchitis during the first year after ileal pouch-anal anastomosis.

METHODS

Forty consecutive patients who underwent ileal pouch-anal anastomosis for ulcerative colitis were randomized to receive either VSL#3 (1 packet containing 900 billion bacteria/day) (n = 20) or an identical placebo (n = 20) immediately after ileostomy closure for 1 year. The patients were assessed clinically, endoscopically, and histologically after 1, 3, 6, 9, and 12 months. Health-related quality of life was assessed using the Inflammatory Bowel Disease Questionnaire.

RESULTS

Two of the 20 patients (10%) treated with VSL#3 had an episode of acute pouchitis compared with 8 of the 20 patients (40%) treated with placebo (log-rank test, z = 2.273; P < 0.05). Treatment with VSL#3 determined a significant improvement in Inflammatory Bowel Disease Questionnaire score, whereas this was not the case with placebo.

CONCLUSIONS

Treatment with VSL#3 is effective in the prevention of the onset of acute pouchitis and improves quality of life of patients with ileal pouch-anal anastomosis.

Intestinal microflora as a therapeutic target in inflammatory bowel disease

Although the causes of inflammatory bowel disease (IBD) remain incompletely understood, increasing evidence implicates intestinal microflora in the pathogenesis of these disorders. Alteration of intestinal flora therefore may offer a plausible therapeutic approach. Although recent data support a potential therapeutic role for probiotics and prebiotics in patients with IBD, such treatments need to be further assessed by large, double-blind controlled trials. A better understanding of the intestinal microflora and the mechanisms of their action may help us to develop more effective treatment for IBD.

Effect of different probiotic preparations on anti-helicobacter pylori therapy-related side effects: a parallel group, triple blind, placebo-controlled study

OBJECTIVES

Several studies show that probiotics may prevent side effects during therapy against Helicobacter pylori (H. pylori). Other reports indicate competitive interaction between some probiotics and H. pylori. We compared efficacy of two different probiotics and one probiotic combination with placebo for preventing anti-H. pylori therapy-related side effects and for improving the eradication rate.

METHODS

A total of 85 H. pylori positive, asymptomatic patients were randomized in four groups to receive probiotic or placebo both during and for 7 days after a 1-wk triple therapy scheme (rabeprazole 20 mg b.id., clarithromycin 500 mg b.i.d., and tinidazole 500 mg b.i.d.). Group I (n = 21) received Lactobacillus GG; group II (n = 22), Saccharomyces boulardii; group III (n = 21), a combination of Lactobacillus spp. and biphidobacteria; and group IV (n = 21), placebo. Subjects filled in weekly symptom questionnaires for 4 wk. Blinded investigators collected and analyzed data. H. pylori status was rechecked after 5-7 wk.

RESULTS

Side effects occurred mainly during the eradication week. None of them caused therapy discontinuation. In all probiotic-supplemented groups, there was a significantly lower incidence of diarrhea and taste disturbance during the eradication week with respect to the placebo group. Overall assessment of tolerability was significantly better in the actively treated patients than in the placebo group. No differences in the incidence of side effects between the probiotic groups were observed. The H. pylori eradication rate was almost identical between the probiotic and placebo groups.

CONCLUSIONS

All the probiotics used were superior to placebo for side effect prevention, but were not associated with better compliance with antibiotic therapy. The effect of probiotic supplementation on side effects during anti-H. pylori regimens seemed to be independent of the probiotic species used.

Probiotics, infection and immunity

PURPOSE OF REVIEW

Taking live bacteria by mouth to improve health (probiotics) is not intuitively rational yet it is a practice with a long history. As interest in the effects on health of the intestinal flora has developed, along with major advances in the technology for studying it, so has come a new interest in establishing the true benefits of probiotic therapy. This review summarizes the most recent contributions to this rapidly developing area.

RECENT FINDINGS

Probiotic bacteria, mainly bifidobacteria and lactobacilli for historical reasons, can prevent or ameliorate some diseases. Many empirical studies have been done, but work to develop the ideal characteristics of probiotics lags behind. Current literature covers survival of probiotics in the gut, mucosal adherence, antibacterial/pathogen mechanisms, effects on immune function and clinical studies.

SUMMARY

Probiotic bacteria are effective in preventing and reducing the severity of acute diarrhoea in children. They are also useful in antibiotic associated diarrhoea but not for elimination of Helicobacter pylori. In inflammatory bowel disease, especially ulcerative colitis, probiotics offer a safe alternative to current therapy. Probiotics have been used to prevent urogenital tract infection with benefit and, perhaps more intriguingly, to reduce atopy in children. Probiotics do not invariably work and study of mechanisms is urgently needed.

New therapeutic approach in the management of intestinal disease: probiotics in intestinal disease in paediatric age

Current evidence supports the view that oral administration of probiotics may be of therapeutic usefulness in several clinical disorders by reestablishing normal flora in the gastrointestinal tract. These entities include inflammatory and infectious diseases of the gut as well as extraintestinal disorders (such as atopic eczema) in which a defective intestinal permeability plays a role. The probiotic effects are attributed to restoration to normal of increased intestinal permeability, unbalanced gut microecology, improved immunological gut barrier function, downregulation of the intestinal inflammatory responses with reduced generation of proinflammatory cytokines. Entities for which the impact of probiotic administration can be considered as proven are Rotavirus diarrhoea, Clostridium difficile diarrhoea, post-antibiotic diarrhoea, allergic diseases. On the other hand, entities for which administration of probiotics is considered under investigation are inflammatory bowel disease, necrotizing enterocolitis, cystic fibrosis, small bowel bacterial contamination, functional gastrointestinal disorders. The value of probiotics as therapy for a variety of gastrointestinal disorders in childhood still needs to be investigated in detail, through well controlled and rigorous studies, including a placebo group and strict criteria of randomisation. Much work needs to be done in this area by clearly defining indications, delivery system, costs, safety long-term effects.

Nutritional factors in inflammatory bowel disease

Dietary antigens may act as important stimuli of the mucosal immune system and have led to the study of nutritional therapy for IBD. Patients with active CD respond to bowel rest, along with total enteral nutrition or TPN. Bowel rest and TPN are as effective as corticosteroids at inducing remission for patients with active CD, although benefits are short-lived. Enteral nutrition is consistently less effective than conventional corticosteroids for treatment of active CD. Use of palatable, liquid polymeric diets in active CD is controversial, but these diets are of equal efficacy when compared with elemental diets. UC has not been treated effectively with either elemental diets or TPN. Fish oil contains n-3-PUFA, which inhibits production of proinflammatory cytokines and has some benefit in the treatment of CD. Topical applications of short-chain fatty acids have benefited diversion colitis and distal UC, whereas probiotics hold promise in the treatment of pouchitis.

Probiotics in gastroenterology

Recent evidence has suggested the potential therapeutic role for probiotics in the prevention or treatment of gastrointestinal diseases. Several studies have shown that probiotics are of benefit in gastrointestinal infections, including viral diarrhea, Clostridium difficile-associated diarrhea, traveler's diarrhea, and antibiotic-associated diarrhea. Recent data support the potential beneficial therapeutic effect in inflammatory bowel disease as well. Other possible indications for probiotic treatment include Helicobacter pylori infection, irritable bowel syndrome, and radiotherapy-associated diarrhea. It is important to select well-characterized preparations; in fact, the viability and survival of many available preparations are unproven. More precise information on the mechanisms by which probiotic strains exert their beneficial effects in vivo is needed. This may provide the scientific rationale for the selection of the best probiotic strains to use in the performance of large, double-blind, controlled clinical trials.

Lactobacillus plantarum 299V in the treatment and prevention of spontaneous colitis in interleukin-10-deficient mice

Interleukin (IL)-10-deficient (IL-10-/-) mice develop colitis under specific pathogen-free (SPF) conditions and remain disease free if kept sterile (germ free [GF]). We used four different protocols that varied the time-points of oral administration of Lactobacillus plantarum 299v (L. plantarum) relative to colonization with SPF bacteria to determine whether L. plantarum could prevent and treat colitis induced by SPF bacteria in IL-10-/- mice and evaluated the effect of this probiotic organism on mucosal immune activation. Assessment of colitis included blinded histologic scores, measurements of secreted colonic immunoglobulin isotypes, IL-12 (p40 subunit), and interferon (IFN)-gamma production by anti-CD3-stimulated mesenteric lymph node cells. Treating SPF IL-10-/- mice with L. plantarum attenuated previously established colonic inflammation as manifested by decreased mucosal IL-12, IFN-gamma, and immunoglobulin G2a levels. Colonizing GF animals with L. plantarum and SPF flora simultaneously had no protective effects. Gnotobiotic IL-10-/- mice monoassociated with L. plantarum exhibited mild immune system activation but no colitis. Pretreatment of GF mice by colonization with L. plantarum, then exposure to SPF flora and continued probiotic therapy significantly decreased histologic colitis scores. These results demonstrate that L. plantarum can attenuate immune-mediated colitis and suggest a potential therapeutic role for this agent in clinical inflammatory bowel diseases.