Probiotic therapy in the prevention of pouchitis onset: decreased interleukin-1beta, interleukin-8, and interferon-gamma gene expression

Postbiotic metabolites produced by Lactobacillus plantarum strains exert selective cytotoxicity effects on cancer cells

Background

Lactobacillus plantarum, a major species of Lactic Acid Bacteria (LAB), are capable of producing postbiotic metabolites (PM) with prominent probiotic effects that have been documented extensively for rats, poultry and pigs. Despite the emerging evidence of anticancer properties of LAB, very limited information is available on cytotoxic and antiproliferative activity of PM produced by L. plantarum. Therefore, the cytotoxicity of PM produced by six strains of L. plantarum on various cancer and normal cells are yet to be evaluated.

Methods

Postbiotic metabolites (PM) produced by six strains of L. plantarum were determined for their antiproliferative and cytotoxic effects on normal human primary cells, breast, colorectal, cervical, liver and leukemia cancer cell lines via MTT assay, trypan blue exclusion method and BrdU assay. The toxicity of PM was determined for human and various animal red blood cells via haemolytic assay. The cytotoxicity mode was subsequently determined for selected UL4 PM on MCF-7 cells due to its pronounced cytotoxic effect by fluorescent microscopic observation using AO/PI dye reagents and flow cytometric analyses.

Results

UL4 PM exhibited the lowest IC₅₀ value on MCF-7, RG14 PM on HT29 and RG11 and RI11 PM on HL60 cell lines, respectively from MTT assay. Moreover, all tested PM did not cause haemolysis of human, dog, rabbit and chicken red blood cells and demonstrated no cytotoxicity on normal breast MCF-10A cells and primary cultured cells including human peripheral blood mononuclear cells, mice splenocytes and thymocytes. Antiproliferation of MCF-7 and HT-29 cells was potently induced by UL4 and RG 14 PM respectively after 72 h of incubation at the concentration of 30% (v/v). Fluorescent microscopic observation and flow cytometric analyses showed that the pronounced cytotoxic effect of UL4 PM on MCF-7 cells was mediated through apoptosis.

Conclusion

In conclusion, PM produced by the six strains of L. plantarum exhibited selective cytotoxic via antiproliferative effect and induction of apoptosis against malignant cancer cells in a strain-specific and cancer cell type-specific manner whilst sparing the normal cells. This reveals the vast potentials of PM from L. plantarum as functional supplement and as an adjunctive treatment for cancer.

Probiotic Modulation of Innate Cell Pathogen Sensing and Signaling Events

There is a growing body of evidence documenting probiotic bacteria to have a beneficial effect to the host through their ability to modulate the mucosal immune system. Many probiotic bacteria can be considered to act as either immune activators or immune suppressors, which have appreciable influence on homeostasis, inflammatory- and suppressive-immunopathology. What is becoming apparent is the ability of these probiotics to modulate innate immune responses via direct or indirect effects on the signaling pathways that drive these activatory or suppressive/tolerogenic mechanisms. This review will focus on the immunomodulatory role of probiotics on signaling pathways in innate immune cells: from positive to negative regulation associated with innate immune cells driving gut mucosal functionality. Research investigations have shown probiotics to modulate innate functionality in many ways including, receptor antagonism, receptor expression, binding to and expression of adaptor proteins, expression of negative regulatory signal molecules, induction of micro-RNAs, endotoxin tolerisation and finally, the secretion of immunomodulatory proteins, lipids and metabolites. The detailed understanding of the immunomodulatory signaling effects of probiotic strains will facilitate strain-specific selective manipulation of innate cell signal mechanisms in the modulation of mucosal adjuvanticity, immune deviation and tolerisation in both healthy subjects and patients with inflammatory and suppressive pathology.

Role of intestinal microbiota in pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by chronic non-specific inflammation of the intestinal tract, and it easily relapses. The pathogenesis of IBD is not fully clear up to now. Intestinal microbiota has been confirmed to play an important role in the development and activation of the intestinal immune system. The changes of intestinal microbiota may induce or aggravate IBD, and regulating intestinal microbiota may have positive effects on the treatment of IBD. This article will discuss the relationship between intestinal microbiota and IBD.

Preserving viability of Lactobacillus rhamnosus GG in vitro and in vivo by a new encapsulation system

Probiotics have shown beneficial effects on health and prevention of diseases in humans. However, a concern for application of probiotics is the loss of viability during storage and gastrointestinal transit. The aim of this study was to develop an encapsulation system to preserve viability of probiotics when they are administrated orally and apply Lactobacillus rhamnosus GG (LGG) as a probiotic model to evaluate the effectiveness of this approach using in vitro and in vivo experiments. LGG was encapsulated in hydrogel beads prepared using pectin, a food grade polysaccharide, glucose, and calcium chloride, and lyophilized by freeze-drying. Encapsulated LGG was cultured in vitro under the condition that mimicked the physiological environment of the human gastrointestinal tract. Compared to non-encapsulated LGG, encapsulation increased tolerance of LGG in the acid condition, protected LGG from protease digestion, and improved shelf time when stored at the ambient condition, in regard of survivability and production of p40, a known LGG-derived protein involved in LGG's beneficial effects on intestinal homeostasis. To evaluate the effects of encapsulation on p40 production in vivo and prevention of intestinal inflammation by LGG, mice were gavaged with LGG containing beads and treated with dextran sulphate sodium (DSS) to induce intestinal injury and colitis. Compared to non-encapsulated LGG, encapsulated LGG enhanced more p40 production in mice, and exerted higher levels of effects on prevention of DSS-induced colonic injury and colitis and suppression of pro-inflammatory cytokine production. These data indicated that the encapsulation system developed in this study preserves viability of LGG in vitro and in vivo, leading to longer shelf time and enhancing the functions of LGG in the gastrointestinal tract. Thus, this encapsulation approach may have the potential application for improving efficacy of probiotics.

Effects of Shewanella putrefaciens on innate immunity and cytokine expression profile upon high stocking density of gilthead seabream specimens

High stocking density increases the number of emerging diseases triggering economic losses worldwide. Probiotics provide an effective and natural solution for preventing some diseases through an improvement of innate immune system among others. In the present work dietary administration of the probiotic Shewanella putrefaciens (known as Pdp11) was evaluated under stress by high stocking density after 2 and 4 weeks of administration to gilthead seabream (Sparus aurata) specimens. Results showed an increase in cellular peroxidase and respiratory burst activity as well as a modulation of cytokine profile when Pdp11 was administered to fish reared at high stocking density. Overall, our results showed how Pdp11 is not only able to improve to some extent the cellular and humoral immunity but also to increase the gene expression profile of pro-inflammatory cytokines such as il1b or il6 in response to high stocking density in gilthead seabream. These findings may support the potential use of this probiotic as functional feed against stress in fish farms.

Role of Probiotics in Crohn's Disease and in Pouchitis

The alterations in the gut microbiota observed in patients with inflammatory bowel disease and in particular in Crohn's disease and in ulcerative colitis patients with pouchitis, provide the rationale for administering probiotic agents in the medical treatment of those conditions. In the maintenance treatment of inactive Crohn's disease probiotics, when administered alone, were found ineffective in preventing clinical and/or endoscopic recurrence. By contrast, a combination of a probiotic agent (eg, Saccharomyces boulardii) with standard pharmacological therapy can promote clinical benefit. In patients with pouchitis, so far only the probiotic mixture VSL #3 proved to effectively prevent relapses after successful antibiotic treatment of active inflammation. Further controlled studies, enrolling higher numbers of patients, are needed to better identify the exact role of probiotics in this area.

Randomized Clinical Trial: Impact of Oral Administration of Saccharomyces boulardii on Gene Expression of Intestinal Cytokines in Patients Undergoing Colon Resection

BACKGROUND

When intestinal microbiota is imbalanced, a patient becomes more vulnerable to infectious complications; intervention with beneficial probiotics may help lower risk for infection. The aim of this study was to measure levels of inflammatory cytokine messenger RNA (mRNA) in surgical samples of intestinal mucosal tissues from patients who were given the probiotic Saccharomyces boulardii before undergoing colon surgery.

METHODS

Thirty-three patients undergoing colon resection were randomly assigned to receive at least 7-day preoperative probiotic treatment (n = 15) or conventional (n = 18) treatment. Probiotic treatment consisted of oral lyophilized S boulardii Cytokine mRNA levels (interleukin [IL]-10, IL-1β, IL-23A, tumor necrosis factor [TNF]-α, IL-12B, interferon-γ [INF-γ], and IL-17A) were measured in samples obtained during the operation. Postoperative infections were also assessed.

RESULTS

Patients who received probiotics had significantly lower mucosal IL-1β, IL-10, and IL-23A mRNA levels than the control group (P = .001, P = .04, and P = .03, respectively). However, mRNA expression of other cytokines did not differ between the 2 groups (P > .05). The incidence of postoperative infectious complications was 13.3% and 38.8% in probiotic and control groups, respectively (P > .05). There was no perioperative mortality in either group. The mean total length of hospital stay was similar between the groups (P > .05).

CONCLUSIONS

Probiotic treatment with S boulardii downregulates both pro- and anti-inflammatory cytokines in the intestinal colonic mucosa with no statistical impact on postoperative infection rates.

Modulation of immunity and inflammatory gene expression in the gut, in inflammatory diseases of the gut and in the liver by probiotics

The potential for the positive manipulation of the gut microbiome through the introduction of beneficial microbes, as also known as probiotics, is currently an active area of investigation. The FAO/WHO define probiotics as live microorganisms that confer a health benefit to the host when administered in adequate amounts. However, dead bacteria and bacterial molecular components may also exhibit probiotic properties. The results of clinical studies have demonstrated the clinical potential of probiotics in many pathologies, such as allergic diseases, diarrhea, inflammatory bowel disease and viral infection. Several mechanisms have been proposed to explain the beneficial effects of probiotics, most of which involve gene expression regulation in specific tissues, particularly the intestine and liver. Therefore, the modulation of gene expression mediated by probiotics is an important issue that warrants further investigation. In the present paper, we performed a systematic review of the probiotic-mediated modulation of gene expression that is associated with the immune system and inflammation. Between January 1990 to February 2014, PubMed was searched for articles that were published in English using the MeSH terms “probiotics" and "gene expression" combined with “intestines", "liver", "enterocytes", "antigen-presenting cells", "dendritic cells", "immune system", and "inflammation". Two hundred and five original articles matching these criteria were initially selected, although only those articles that included specific gene expression results (77) were later considered for this review and separated into three major topics: the regulation of immunity and inflammatory gene expression in the gut, in inflammatory diseases of the gut and in the liver. Particular strains of Bifidobacteria, Lactobacilli, Escherichia coli, Propionibacterium, Bacillus and Saccharomyces influence the gene expression of mucins, Toll-like receptors, caspases, nuclear factor-κB, and interleukins and lead mainly to an anti-inflammatory response in cultured enterocytes. In addition, the interaction of commensal bacteria and probiotics with the surface of antigen-presenting cells in vitro results in the downregulation of pro-inflammatory genes that are linked to inflammatory signaling pathways, whereas other anti-inflammatory genes are upregulated. The effects of probiotics have been extensively investigated in animal models ranging from fish to mice, rats and piglets. These bacteria induce a tolerogenic and hyporesponsive immune response in which many genes that are related to the immune system, in particular those genes expressing anti-inflammatory cytokines, are upregulated. By contrast, information related to gene expression in human intestinal cells mediated by the action of probiotics is scarce. There is a need for further clinical studies that evaluate the mechanism of action of probiotics both in healthy humans and in patients with chronic diseases. These types of clinical studies are necessary for addressing the influence of these microorganisms in gene expression for different pathways, particularly those that are associated with the immune response, and to better understand the role that probiotics might have in the prevention and treatment of disease.

Effects of immunomodulatory supplementation with Lactobacillus rhamnosus on airway inflammation in a mouse asthma model

BACKGROUND

Asthma is a common allergic disease. In previous studies, probiotics improved the balance of intestinal microbes, reduced inflammation, and promoted mucosal tolerance. This study investigated whether oral administrations of Lactobacillus rhamnosus GG (LGG) inhibited allergen (ovalbumin or OVA)-induced airway inflammation in a mouse asthma model.

METHODS

The allergy/asthma animal model in this study was sensitization with OVA. After intranasal challenge with OVA, the airway inflammation and hyper-responsiveness were determined by a Buxco system, bronchoalveolar lavage fluid analysis with Liu stain, and enzyme-linked immunosorbent assay. Histopathologic changes in the lung were detected by hematoxylin and eosin staining and immunohistochemistry staining.

RESULTS

Both pre- and post-treatment with LGG suppressed the airway hyper-responsiveness to methacholine and significantly decreased the number of infiltrating inflammatory cells and Th2 cytokines in bronchoalveolar lavage fluid and serum compared with the OVA-sensitized mice. In addition, LGG reduced OVA-specific IgE levels in serum. Oral LGG decreased matrix metalloproteinase 9 expression in lung tissue and inhibited inflammatory cell infiltration.

CONCLUSION

LGG had an anti-inflammatory effect on OVA-induced airway inflammation and might be an additional or supplementary therapy for allergic airway diseases.

Immunomodulatory activity of two potential probiotic strains in LPS-stimulated HT-29 cells

The relative expression of mucin, pro- and anti-inflammatory genes besides other signaling molecules in HT-29 cells by two test probiotic strains of Lactobacillus plantarum Lp9 and Lp91 and the reference strain L. plantarum 5276 was evaluated by RT-qPCR using Relative Expression Software Tool qBase-Plus under in vitro simulated gut conditions. Ten house keeping genes were evaluated by using geNorm 3.4 excel based application. The most stable genes were RPL27, ACTB and B2M which were subsequently used for calculating the normalization factor. Under pretreatment conditions (4 h probiotic treatment, followed by lipopolysaccharide challenge for 3 h), all the three strains evoked downregulation of IL-8 expression by ~100 %, while in case of TNF-α, the downregulation of the relative gene expression was at the rate of 98.2, 93.8 and 98.0 % with Lp5276, Lp9 and Lp91, respectively, under the same set of conditions. Lp91 evoked maximum downregulation of IL12p35 and IFN-γ with corresponding fold reduction in relative expression of the two genes by 96.5 and 96.7 % during pre-treatment conditions. However, IL-10 and IFN-α were significantly upregulated to the extent of 8.13 ± 0.36 and 2.62 ± 0.14 fold by Lp91 under the same conditions. Lp9 and Lp91 were also quite effective in inducing the expression of Cox-1 and Cox-2 in HT-29 cells as can be reflected from their ratios, i.e., 5.90 and 6.50 (under pretreatment conditions); 3.79 and 4.36 (under co-culture conditions). Thus, the two putative indigenous L. plantarum strains Lp9 and Lp91 demonstrated immunomodulating functions in HT-29 cells at significant levels under different experimental conditions.

Antibodies against glycoprotein 2 are novel markers of intestinal inflammation in patients with an ileal pouch

BACKGROUND AND AIMS

The Crohn's disease (CD)-specific pancreatic auto-antibodies (PAB), have been recently identified to target glycoprotein 2 (GP2). Pouchitis is an inflammation of the small bowel developing in up to 60% of ulcerative colitis patients undergoing proctocolectomy and ileal pouch anal anastomosis. Occurrence of CD-specific antibodies was reported to be a predictor of pouchitis. We aimed to assess the prevalence of anti-GP2 antibodies (anti-GP2) in the serum and feces of pouch patients and to correlate them with clinical parameters. Furthermore, we examined mucosal expression of the GP2 protein in the pouch.

METHODS

Pouch patients were prospectively recruited and checked for clinical, endoscopic, and laboratory markers of inflammation. IgG and IgA anti-GP2 levels in serum and fecal samples were determined using ELISA. GP2 protein was assessed by immunohistochemistry.

RESULTS

Anti-GP2 was elevated in both serum and fecal samples of patients with inflamed compared to those with non-inflamed pouches and patients with familial-adenomatous polyposis after surgery (p<0.05, respectively). Moreover, patients with CD-like complications exhibited significantly higher anti-GP2 titers than those without CD-like complications (p≤0.01). High levels of anti-GP2 correlated with more frequent bowel movements per day and with the presence of at least one anti-glycan antibody (p≤0.05). GP2 itself was more abundant in the mucosa of patients with chronic pouchitis.

CONCLUSIONS

Anti-GP2 exists in the serum and feces of pouch patients and correlates with pouch inflammation, and presence of other serological markers. Thus, anti-GP2 may contribute to better stratification of pouchitis, more-so when the inflammation exhibits CD-like complications.

Microbial ecological agents and inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a chronic non-specific inflammatory condition of the gastrointestinal tract with unknown etiology. During the exploration of the etiology, treatment and other aspects of IBD, it has been gradually realized that microbial ecological agents (MEAs) are helpful in the treatment of IBD. This article reviews the relationship between MEAs and IBD with regard to the intestinal environment in IBD, the therapeutic effect of MEA in IBD and the possible mechanisms involved.

Probiotic bacteria in the prevention and the treatment of inflammatory bowel disease

Definitive curative strategies for inflammatory bowel disease remain challenging for physicians and patients. For decades, probiotic organisms have been used in various gastrointestinal diseases. Only recently has comprehension of the pathophysiology of inflammatory bowel disease developed to the point where the significance of the host gastrointestinal microbial population is seen to have marked influence on the initiation and ongoing inflammatory processes of Crohn disease and ulcerative colitis. Well-designed, large randomized controlled trials using probiotics in patients with inflammatory bowel disease are required for probiotics to become mainstream therapy.

Nutritional and probiotic supplementation in colitis models

In vitro and animals models have long been used to study human diseases and identify novel therapeutic approaches that can be applied to combat these conditions. Ulcerative colitis and Crohn's disease are the two main entities of inflammatory bowel disease (IBD). There is an intricate relationship between IBD features in human patients, in vitro and animal colitis models, mechanisms and possible therapeutic approaches in these models, and strategies that can be extrapolated and applied in humans. Malnutrition, particularly protein-energy malnutrition and vitamin and micronutrient deficiencies, as well as dysregulation of the intestinal microbiota, are common features of IBD. Based on these observations, dietary supplementation with essential nutrients known to be in short supply in the diet in IBD patients and with other molecules believed to provide beneficial anti-inflammatory effects, as well as with probiotic organisms that stimulate immune functions and resistance to infection has been tested in colitis models. Here we review current knowledge on nutritional and probiotic supplementation in in vitro and animal colitis models. While some of these strategies require further fine-tuning before they can be applied in human IBD patients, their intended purpose is to prevent, delay or treat disease symptoms in a non-pharmaceutical manner.

Probiotics in the management of inflammatory bowel disease: a systematic review of intervention studies in adult patients

INTRODUCTION

Mounting evidence suggests an important role for the intestinal microbiota in the chronic mucosal inflammation that occurs in inflammatory bowel disease (IBD), and novel molecular approaches have further identified a dysbiosis in these patients. Several mechanisms of action of probiotic products that may interfere with possible aetiological factors in IBD have been postulated.

OBJECTIVE

Our objective was to discuss the rationale for probiotics in IBD and to systematically review clinical intervention studies with probiotics in the management of IBD in adults.

METHODS

A systematic search was performed in PubMed up to 1 October 2011, using defined keywords. Only full-text papers in the English language addressing clinical outcomes in adult patients were included. The 41 eligible studies were categorized on disease type (ulcerative colitis [UC] with/without an ileo-anal pouch and Crohn's disease [CD]) and disease activity. Pooled odds ratios were only calculated per probiotic for a specific patient group when more than one randomized controlled trial was available.

RESULTS

Well designed randomized controlled trials supporting the application of probiotics in the management of IBD are still limited. Meta-analyses could only be performed for a limited number of studies revealing overall risk ratios of 2.70 (95% CI 0.47, 15.33) for inducing remission in active UC with Bifido-fermented milk versus placebo or no additive treatment (n = 2); 1.88 (95% CI 0.96, 3.67) for inducing remission in active UC with VSL#3 versus placebo (n = 2); 1.08 (95% CI 0.86, 1.37) for preventing relapses in inactive UC with Escherichia coli Nissle 1917 versus standard treatment (n = 3); 0.17 (95% CI 0.09, 0.33) for preventing relapses in inactive UC/ileo-anal pouch anastomosis (IPAA) patients with VSL#3 versus placebo; 1.21 (95% CI 0.57, 2.57) for preventing endoscopic recurrences in inactive CD with Lactobacillus rhamnosus GG versus placebo (n = 2); and 0.93 (95% CI 0.63, 1.38) for preventing endoscopic recurrences in inactive CD with Lactobacillus johnsonii versus placebo (n = 2).

CONCLUSION

Further well designed studies based on intention-to-treat analyses by several independent research groups are still warranted to support the promising results for E. coli Nissle in inactive UC and the multispecies product VSL#3 in active UC and inactive pouch patients. So far, no evidence is available to support the use of probiotics in CD. Future studies should focus on specific disease subtypes and disease location. Further insight into the aetiology of IBD and the mechanisms of probiotic strains will aid in selecting probiotic strains for specific disease entities and disease locations.

Etiology of pouchitis

Restorative proctocolectomy with ileal-pouch anal anastomosis (RPC) is the operation of choice for ulcerative colitis (UC) patients requiring surgery. It is also used for patients with familial adenomatous polyposis (FAP). Pouchitis accounts for 10% of pouch failures. It is an idiopathic inflammatory condition that may occur in up to 50% of patients after RPC for UC. It is rarely seen in FAP patients after RPC. The etiology of pouchitis remains unclear. An overlap with UC is suggested by the frequency with which pouchitis affects patients with UC compared with FAP patients. There is significant clinical evidence implicating bacteria in the pathogenesis of pouchitis. Studies using culture and molecular methods demonstrate a dysbiosis of the pouch microbiota in pouchitis. Risk factors, genetic associations, and serological markers of pouchitis suggest that the interactions between the host immune responses and the pouch microbiota underlie the etiology of this idiopathic inflammatory condition. Here we present a detailed review of the data focusing on the pouch microbiota and the immune responses that support this hypothesis. We also discuss the contribution of luminal metabolic factors and the epithelial membrane in the etiology of this inflammatory process. The ileoanal pouch offers a unique opportunity to study the inter-relationships between the gut microbiota and host immune responses from before the onset of disease. For this reason the study of pouchitis could serve as a human model that significantly enhances our understanding of inflammatory bowel diseases in general.

Microbes, intestinal inflammation and probiotics

Inflammatory bowel disease (IBD) is known for causing disturbed homeostatic balance among the intestinal immune compartment, epithelium and microbiota. Owing to the emergence of IBD as a major cause of morbidity and mortality, great efforts have been put into understanding the sequence of intestinal inflammatory events. Intestinal macrophages and dendritic cells act in a synergistic fashion with intestinal epithelial cells and microbiota to initiate the triad that governs the intestinal immune responses (whether inflammatory or regulatory). In this review, we will discuss the interplay of intestinal epithelial cells, bacteria and the innate immune component. Moreover, whether or not genetic intervention of probiotic bacteria is a valid approach for attenuating/mitigating exaggerated inflammation and IBD will also be discussed.

Anti-inflammatory and immunomodulatory efficacy of indigenous probiotic Lactobacillus plantarum Lp91 in colitis mouse model

Probiotics can affect the immune homeostasis by altering the gut microbial balance and enhancing the immune system of gut, thus benefits in Inflammatory Bowel Disease, including Crohn's disease and Ulcerative colitis. Relative gene expression of pro, anti-inflammatory cytokines and other molecules in 2,4,6-trinitrobenzene sulfonic acid-induced colitis mouse model against Lactobacillus plantarum Lp91 (L. plantarum Lp91) was investigated by reverse transcription-quantitative PCR (RT-qPCR) using relative expression software tool (REST 2008 V2.0.7). L. plantarum Lp91 evoked significant down regulation of TNF-α and COX2 to 0.026 and 0.077 fold in colitis mouse model. No significant difference in expression of IL-12a cytokine in colitis mouse challenged with L. plantarum Lp91 was also observed. IL-10 was significantly up-regulated to 37.813 and 1.327 fold in colitis and non-colitis mouse challenged with L. plantarum Lp91. While, other anti-inflammatory markers i.e. COX1, IL-4 and IL-6 were significantly up regulated in colitis mouse challenged with L. plantarum Lp91. MUC2 gene was significantly up regulated to 2.216 fold in non-colitis group. L. plantarum Lp91, an indigenous probiotic culture, the main subject of this project exhibited strong immunemodulatory properties under in vivo conditions in mouse colitis model.

Iridoid glycosides fraction of Folium syringae leaves modulates NF-κB signal pathway and intestinal epithelial cells apoptosis in experimental colitis

BACKGROUND AND AIMS

Iridoid glycosides (IG), the major active fraction of F. syringae leaves has been demonstrated to have strong anti-inflammatory properties to ulcerative colitis (UC) in our previous study. The aim of this study was to investigate whether IG modulates the inflammatory response in experimental colitis at the level of NF-κB signal pathway and epithelial cell apoptosis.

METHODS

UC in rats was induced by administration with dextran sulfate sodium (DSS) in drinking water. The inflammatory damage was assessed by disease activity index (DAI), macroscopic findings, histology and myeloperoxidase (MPO) activity. The effect of IG on pro-inflammatory cytokines TNF-α, IL-8, COX-2 and regulatory peptide TGF-β1 was measured. Epithelial cell apoptosis and the protein and mRNA expressions of Fas/FasL, Bcl-2/Bax, caspase-3, NF-κB p65, IκBα, p-IκBα and IKKβ were detected by TUNEL method, immunohistochemistry, Western blotting and real-time quantitative PCR, respectively.

RESULTS

IG significantly ameliorated macroscopic damage and histological changes, reduced the activity of MPO, and strongly inhibited epithelial cell apoptosis. Moreover, IG markedly depressed TNF-α, IL-8, COX-2 and TGF-β1 levels in the colon tissues in a dose-dependent manner. Furthermore, IG significantly blocked of NF-κB signaling by inhibiting IκBα phosphorylation/degradation and IKKβ activity, down-regulated the protein and mRNA expressions of Fas/FasL, Bax and caspase-3, and activated Bcl-2 in intestinal epithelial cells.

CONCLUSIONS

These results demonstrated for the first time that IG possessed marked protective effects on experimental colitis through inhibition of epithelial cell apoptosis and blockade of NF-κB signal pathway.

Probiotics and small bowel mucosa: Molecular aspects of their interactions

Probiotics are described as "friendly bacteria" that could improve the intestine defense by interacting with the resident microflora. There is a large body of evidence suggesting that consumption of functional food containing probiotics exerts positive effects on human health. Several clinical trials have highlighted the efficiency of probiotics in the prevention and treatment of different gastrointestinal disorders including the prevention of antibiotic associated diarrhea, the remission in patients with inflammatory bowel disease, beneficial effects against Helicobacter pylori infection, positive effects in patients affected by allergies and atopic diseases. The clinical benefits of probiotics use are mainly attributed to their antimicrobial substances production and their positive interactions with the enterocytes to reinforce the intestinal epithelial barrier. Moreover, there is evidence suggesting that probiotics stimulate both specific and non-specific host immune responses. Recently, have been published some experiments performed with the DNA microarray technology which provided a global gene screening of the complex bacteria-host interplay. Nevertheless, the molecular mechanisms by which probiotics enhance the intestinal host defense are still not completely elucidated. Here, we review the experiments and clinical studies to date on the complex mechanisms regulating the communication between probiotics and their hosts.

Therapeutical use of probiotic formulations in clinical practice

BACKGROUND & AIMS

The spreading of gastrointestinal diseases is growing all over the world. Although for some of them an effective therapeutic approach has been found, palliation rather than cure is very frequent due to a partial knowledge of their aetiology and pathogenesis. This review, analyzing the main clinical studies, aims at being a state of the art update of the use of probiotic formulations in daily practice.

METHODS

In this review we include all the most significant clinical trials involving the use of probiotic formulations for the treatment of several pathologies.

RESULTS

Dysbiosis has been observed in irritable bowel syndrome patients. Probiotics may exert a beneficial effect on Crohn's disease affected patients who have shown gut microbiota antigens and altered wall permeability. Moreover some probiotic formulations seem to enhance the therapy for Helicobacter Pylori reducing its pathogenic potential. Intestinal ecology imbalance has been also linked to cancer induction, allergy, skin and urogenital diseases. In addition probiotics administration seems to be particularly useful to ease post-operative complications.

CONCLUSION

Further future clinical trials, involving large numbers of patients, will be mandatory to achieve definite evidence of the preventive and curative role of probiotics in medical practice.

Activation of signal transducer and activator of transcription-1 (STAT-1) and differential expression of interferon-gamma and anti-inflammatory proteins in pelvic ileal pouches for ulcerative colitis and familial adenomatous polyposis

Pouchitis after total rectocolectomy is the most common complication of ulcerative colitis (UC). The immunological mechanisms involved in the genesis of pouchitis are unclear. Therefore, we evaluated the inflammatory activity in normal ileal pouch mucosa by determining signal transducers and activators of transcription (STAT-1) activation and cytokine expression in patients operated for UC and familial adenomatous polyposis (FAP). Eighteen asymptomatic patients, who underwent total rectocolectomy and J pouch, were evaluated: nine with UC and nine with FAP. The activation of STAT-1 and cytokine expression were determined by immunoblot of total protein extracts from pouch mucosal biopsies. The absence of pouchitis was assessed by clinical, histological and endoscopic parameters, according to the Pouchitis Disease Activity Index. The patients were not receiving any medication. Analysis of variance (anova) and Tukey-Kramer's test were applied. The local ethical committee approved the study and informed consent was signed by all participants. STAT-1 activation was increased in UC when compared to FAP and controls (P < 0.05). Higher levels of interferon (IFN)-gamma expression were observed in UC patients when compared to the control group (P < 0.05), but were similar to FAP. In contrast, cytokine signalling (SOCS-3) and interleukin (IL)-10 expression were similar in all groups (P > 0.05). These findings could explain the higher susceptibility to this inflammatory complication in UC when compared to FAP. A tendency towards increased levels of IFN-gamma and STAT-1 in patients with UC, even without clinical and endoscopic evidence of pouchitis, was observed; studying inflammatory activity in asymptomatic ileal pouches may help understanding of the pathogenesis of pouchitis.

Novel perspectives in probiotic treatment: the efficacy and unveiled mechanisms of the physiological functions

Probiotics are defined as "live microorganisms which confer a health benefit on the host" when administered in adequate amounts, and have potential effects for maintaining intestinal development, nutrition, and treating intestinal inflammations, functional disorders, and other extra-intestinal diseases. Although the benefits of probiotics for human health were first noted over 100 years ago, the analysis of probiotic functions began in earnest only 20 years ago. Probiotics, such as some strains of Lactobacillus, Bifidobacterium, Escherichia coli, and Bacillus subtilis, inhibit the growth of pathogenic bacteria, induce competitive effects for the adherent of pathogenic bacteria and their toxins to intestinal epithelia, induce cytoprotective heat shock proteins, enhance the intestinal barrier function, and modulate the host immune responses. The crosstalk between the host and the probiotics appears to be mediated by bacteria-derived effectors, which can be sensed with multiple systems, including the Toll-like receptors and cell membrane transporters. Future analyses will identify more probiotic-derived effectors, the recognition mechanisms of these effectors, and the subsequent changes of the intestinal epithelia and immune cells for each probiotic treatment. For clinical use, a procedure that objectively evaluates the ability of each probiotic effect will help establish a standard for choosing the most valuable strain and its proper dose for each individual patient.

Detection of epithelial apoptosis in pelvic ileal pouches for ulcerative colitis and familial adenomatous polyposis

Background

Ileal pouch-anal anastomosis (IPAA) is the surgical procedure of choice for patients with refractory ulcerative colitis (UC) and for familial adenomatous polyposis (FAP) with many rectal polyps. Pouchitis is one of the more frequent complications after IPAA in UC patients; however, it is rare in FAP.

Objective

Evaluate pro-apoptotic activity in endoscopically and histological normal mucosa of the ileal pouch in patients with UC and FAP.

Methods

Eighteen patients (nine with UC and nine with FAP) with J pouch after total rectocolectomy were studied. Biopsies were obtained from the mucosa of the pouch and from normal ileum. The specimens were snap-frozen and the expressions of Bax and Bcl-2 were determined by immunoblot of protein extracts and by immunohistochemistry analysis. FADD, Caspase-8, APAF-1 and Caspase-9 were evaluated by immunoprecipitation and immunoblot.

Results

Patients with UC had significantly higher protein levels of Bax and APAF-1, Caspase-9 than patients with FAP, but were similar to controls. The expressions of Bcl-2 and FADD, Caspase-8 were similar in the groups. Immunohistochemistry for Bax showed less intensity of immunoreactions in FAP than in UC and Controls. Bcl-2 immunostaining was similar among the groups.

Conclusion

Patients with FAP present lower levels of pro-apoptotic proteins in all methods applied, even in the absence of clinical and endoscopic pouchitis and dysplasia in the histological analysis. These findings may explain a tendency of up-regulation of apoptosis in UC patients, resulting in higher rates of progression to pouchitis in these patients, which could correlate with mucosal atrophy that occurs in inflamed tissue. However, FAP patients had low pro-apoptotic activity in the mucosa, and it could explain the tendency to low cell turn over and presence of adenomas in this syndrome.

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.

Intestinal bacteria and inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) are the two principal forms of inflammatory bowel disease (IBD). Animal studies show that bacteria are involved in the etiology of IBD, and much is now known about the inflammatory processes associated with CD and UC, as well as the underlying genetic, environmental, and lifestyle issues that can affect an individual's predisposition to these diseases. However, while a number of candidate microorganisms have been put forward as causative factors in IBD, the primary etiologic agents are unknown. This review discusses the potential role of luminal and mucosal microbial communities in the etiology of IBD, and outlines studies that have been made using a variety of biotherapeutic therapies, involving the use of antibiotics, probiotics, prebiotics, and synbiotics.

Mechanisms of probiotic action: Implications for therapeutic applications in inflammatory bowel diseases

Probiotics are defined as nonpathogenic living microorganisms, including some commensal bacterial flora, which have beneficial effects on host health and disease prevention and/or treatment. Clinical trials have shown beneficial effects of probiotics on several human diseases, such as inflammatory bowel diseases (IBDs), which are among the most-studied diseases testing probiotics as a potential therapy. However, a significant question regarding clinical use of probiotics is the mechanism underlying the wide range of actions. Studies discussed in this review suggest 3 distinct cellular and molecular mechanisms for probiotic regulation in IBD therapy: 1) Probiotics block pathogenic bacterial effects by producing bactericidal substances and competing with pathogens and toxins for adherence to the intestinal epithelium; 2) Probiotics regulate immune responses by enhancing the innate immunity and modulating pathogen-induced inflammation via toll-like receptor-regulated signaling pathways; and 3) Probiotics regulate intestinal epithelial homeostasis by promoting intestinal epithelial cell survival, enhancing barrier function, and stimulating protective responses. Probiotics modulate host cell signaling pathways, including Akt, mitogen-activated protein kinases, and nuclear factor-kappaB to mediate these intestinal epithelial functions. It is hoped that developing a mechanistic understanding of probiotic action will provide the rationale to support the development of new hypothesis-driven studies to define the clinical efficacy in preventive, adjunctive, or alternative treatments for IBD.

Development of pouchitis following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis: A role for serological markers and microbial pattern recognition receptor genes

BACKGROUND AND AIMS

Pouchitis, the most common complication after proctocolectomy with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis, has been attributed to altered composition of faecal flora. We investigated the role of antimicrobial and antiglycan antibodies and polymorphisms in microbial pattern recognition receptor genes.

METHODS

Clinical charts of all 184 patients with ulcerative colitis who underwent IPAA between 1990-2004 were reviewed for pre- and post-operative disease course.

RESULTS

Follow-up data were available in 172 patients [67 female, median age at proctocolectomy 39.1 years]. During a median follow-up of 6.7 (interquartile range 3.7-10.5) years, 80 patients (47%) developed at least one episode of pouchitis. Cox proportional-hazard regression identified extra-intestinal manifestations [HR 1.78 (95%CI 1.10-2.88), p=0.020], a GT/TT genotype at Toll-like-receptor-1 S87I [HR 1.64 (1.01-2.66), p=0.047], anti-chitobioside carbohydrate antibodies [HR 2.03 (1.11-3.70), p=0.021] and young age at diagnosis [p=0.003] to be independently associated with pouchitis. Factors associated with chronic pouchitis, diagnosed in 33 patients (19%), were extra-intestinal manifestations [HR 2.45 (1.07-5.62), p=0.034], backwash ileitis [HR 3.15 (1.10-9.00), p=0.032], outer-membrane porin antibodies [HR 2.67 (1.20-5.94), p=0.016] and young age at proctocolectomy [p=0.008].

CONCLUSIONS

: The reported association with antibodies and Toll-like-receptor-1 supports the pathophysiological role of the faecal flora in the development of pouchitis.

Differential expression of pro-inflammatory cytokines and a pro-apoptotic protein in pelvic ileal pouches for ulcerative colitis and familial adenomatous polyposis

BACKGROUND

Pouchitis after total rectocolectomy is among the most common complications of patients with ulcerative colitis (UC). However, its frequency is quite rare in patients with familial adenomatous polyposis (FAP). We evaluated the inflammatory and pro-apoptotic activity in endoscopically normal mucosa of the ileal pouch in patients with UC and FAP.

METHODS

Twenty patients (10 with UC and 10 with FAP) with "J" pouch after total proctocolectomy were studied as were 10 normal controls. Biopsies were obtained from the mucosa of the pouch of UC and FAP patients and from the normal ileum of controls. The expression levels of TNF-alpha, IL-1beta, IL-6, IL-8 and phospho-BAD were determined by immunoblotting. Activated NFkappaB was evaluated by immuno-precipitation and immunoblotting for IkappaB kinase beta.

RESULTS

Patients with UC had higher levels of IL-1beta, IL-6, IL-8 and TNF-alpha than patients with FAP. The level of TNF-alpha was higher in patients with UC than in patients with FAP; both patient groups had TNF-alpha levels higher than controls. Activation of NFkappaB was similar in all three groups. The expression of phospho-BAD was significantly lower in patients with FAP than in patients with UC.

CONCLUSIONS

As compared with patients with FAP, patients with UC presented increased levels of some pro-inflammatory cytokines, even in the absence of clinical or endoscopic signs of pouchitis. Patients with FAP presented lower levels of pro-inflammatory proteins and of phospho-BAD. These findings may explain the higher rates of progression to pouchitis in UC patients, which could correlate with mucosal atrophy that occurs in inflamed tissue.

Probiotic administration in patients with ileal pouch-anal anastomosis for ulcerative colitis is associated with expansion of mucosal regulatory cells

BACKGROUND

Probiotics have anti-inflammatory effects in patients with inflammatory bowel disease and appear to regulate mucosal immune response through reductions in proinflammatory cytokines. The probiotic VSL#3 prevents pouchitis if started within a week of ileostomy closure and maintains remission following antibacterial treatment in patients with refractory or recurrent pouchitis. However, the efficacy of probiotics and their effects on regulatory cells if started at a greater time after surgery in patients undergoing ileal pouch anal anastomosis (IPAA) for ulcerative colitis are unknown.

METHODS

We conducted an open-label study in which 31 patients at different periods from surgery without signs and symptoms of pouchitis were randomized to 2 sachets of VSL#3 once daily or no treatment for 12 months. Pouchitis disease activity index (PDAI) was evaluated at baseline and after 3, 6, and 12 months. The percentage of CD4+ T lymphocytes expressing CD25 and the inactive form of transforming growth factor-beta [latency-associated peptide (LAP)] were evaluated at baseline and after 3 and 6 months in peripheral-blood mononuclear cells and mucosal biopsies. Variation in tissue interleukin-1beta and Foxp3 mRNA expression was also evaluated.

RESULTS

During the study period, VSL#3-treated patients showed a significant reduction in PDAI score and a significant increase in the percentage of mucosal CD4+CD25(high) and CD4+ LAP-positive cells compared with baseline values. Tissue samples at different points showed a significant reduction in IL-1beta mRNA expression, and a significant increase in Foxp3 mRNA expression.

CONCLUSIONS

We conclude that VSL#3 administration in patients with IPAA modulates the PDAI and expands the number of mucosal regulatory T cells.

The probiotic Escherichia coli strain Nissle 1917 induces gammadelta T cell apoptosis via caspase- and FasL-dependent pathways

Human gammadelta T cells play a vital role in the innate and adaptive immune response to microbial antigens by acting as antigen-presenting cells while at the same time being capable of directly activating CD4(+) T cells. Pathogenic microbes or loss of tolerance toward the host's own microflora trigger many diseases including inflammatory bowel diseases. We previously demonstrated that Escherichia coli Nissle 1917 directly interacts with the adaptive immune system by regulating central T cell functions. Here we aimed to investigate whether E. coli Nissle regulates gammadelta T cell function, thereby linking the innate and adaptive immune system. In our study, we demonstrate that, in contrast to the other probiotic strains tested, E. coli Nissle increased activation, cell cycling and expansion of gammadelta, but not alphabeta T cells. In gammadelta T cells, E. coli Nissle reduced tumor necrosis factor-alpha secretion but increased IL-6 and CXCL8 release. However, after activation, only E. coli Nissle induced gammadelta T cell apoptosis, mediated via Toll-like receptor-2 by caspase- and FasLigand-dependent pathways. gammadelta T cells play an important role in the recognition of microbial antigens and the perpetuation of inflammatory processes. The demonstration that E. coli Nissle, but not the other bacteria tested, profoundly regulate gammadelta T cell function contributes to explaining the biological function of this probiotic strain in inflammatory diseases and provides us with a better understanding of the role of gammadelta T cells.

Colifagina, a Novel Preparation of 8 Lysed Bacteria Ameliorates Experimental Colitis

Immune reactivity towards the bacterial intestinal flora plays an important part in the pathogenesis of inflammatory bowel disease. Administration of probiotic bacteria has beneficial effects on infectious and inflammatory diseases, principally in bowel disorders. However, little is known about the administration of soluble bacterial antigens in intestinal inflammation. We investigated the therapeutic effects of colifagina in experimental colitis. To assess this effect, C57BL/6 mice with dextran sulphate sodium-induced colitis were treated with colifagina, or with a placebo, for a period of 10 days. The mice were monitored, and inflammation was assessed by disease activity index (DAI). Analysis of fecal IgA concentration and measurement of IgA and inflammatory chemokine production in organ colonic culture was performed by ELISA. Clinically and histologically, bacterial-lysate-treated mice revealed significantly fewer DAI and a reduction of colonic histological inflammation. Treatment of healthy mice with colifagina significantly increased the fecal concentration of IgA and IgA production in organ culture. Colifagina administration in DSS-treated mice significantly increased the fecal concentration of IgA and IgA production in organ culture. MIP-1, MIP-2 and RANTES concentrations in colonic organ culture were significantly lower in colifagina-treated mice than in the placebo group. The use of colifagina is effective in amelioration of murine colitis.

Probiotics, immunomodulation, and health benefits

Probiotics are defined as live microorganisms that, when administered in adequate amount, confer a health benefit on the host. Amongst the many benefits associated with the consumption of probiotics, modulation of the immune system has received the most attention. Several animal and human studies have provided unequivocal evidence that specific strains of probiotics are able to stimulate as well as regulate several aspects of natural and acquired immune responses. There is also evidence that intake of probiotics is effective in the prevention and/or management of acute gastroenteritis and rotavirus diarrhoea, antibiotic-associated diarrhoea and intestinal inflammatory disorders such as Crohn's disease and pouchitis, and paediatric atopic disorders. The efficacy of probiotics against bacterial infections and immunological disorders such as adult asthma, cancers, diabetes, and arthritis in humans remains to be proven. Also, major gaps exist in our knowledge about the mechanisms by which probiotics modulate immune function. Optimum dose, frequency and duration of treatment required for different conditions in different population groups also remains to be determined. Different probiotic strains vary in their ability to modulate the immune system and therefore efficacy of each strain needs to be carefully demonstrated through rigorously designed (randomised, double-blind, placebo-controlled) studies. This chapter provides an over view of the immunomodulatory effects of probiotics in health and disease, and discusses possible mechanisms through which probiotics mediate their disparate effects.

Commensal bacteria and expression of two major intestinal chemokines, TECK/CCL25 and MEC/CCL28, and their receptors

BACKGROUND

CCL25/TECK and CCL28/MEC are CC chemokines primarily expressed in thymic dendritic cells and mucosal epithelial cells. Their receptors, CCR9 and CCR10, are mainly expressed on T and B lymphocytes. In human, mouse, pig and sheep CCL25 and CCL28 play an important role in the segregation and the compartmentalization of the mucosal immune system. As evidenced by early comparisons of germ-free and conventional animals, the intestinal bacterial microflora has a marked effect on host intestinal immune functions. However, little is known about the impact of bacterial colonization on constitutive and induced chemokine expressions as well as on the generation of anti-inflammatory mechanisms.

METHODOLOGY/PRINCIPAL FINDINGS

Therefore, we decided to focus by qPCR on the mRNA expression of two main gut chemokines, CCL25 and CCL28, their receptors CCR9 and CCR10, the Tregs marker Foxp3 and anti-inflammatory cytokines TGF-beta and IL-10 following colonization with different bacterial species within the small intestine. To accomplish this we used an original germ-free neonatal pig model and monoassociated pigs with a representative Gram-negative (Escherichia coli) or Gram-positive (Lactobacillus fermentum) commensal bacteria commonly isolated from the neonatal pig intestine. Our results show a consistent and marked effect of microbial colonization on the mRNA expression of intestinal chemokines, chemokine receptors, Foxp3 and TGF-beta. Moreover, as evidenced by in vitro experiments using two different cell lines, the pattern of regulation of CCL25 and CCL28 expression in the gut appears complex and suggests an additional role for in vivo factors.

CONCLUSIONS/SIGNIFICANCE

Taken together, the results highlight the key role of bacterial microflora in the development of a functional intestinal immune system in an elegant and relevant model for human immune system development.

A key role of dendritic cells in probiotic functionality

BACKGROUND

Disruption of the intestinal homeostasis and tolerance towards the resident microbiota is a major mechanism involved in the development of inflammatory bowel disease. While some bacteria are inducers of disease, others, known as probiotics, are able to reduce inflammation. Because dendritic cells (DCs) play a central role in regulating immune responses and in inducing tolerance, we investigated their role in the anti-inflammatory potential of probiotic lactic acid bacteria.

METHODOLOGY/PRINCIPAL FINDINGS

Selected LAB strains, while efficiently taken up by DCs in vitro, induced a partial maturation of the cells. Transfer of probiotic-treated DCs conferred protection against 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Protection was associated with a reduction of inflammatory scores and colonic expression of pro-inflammatory genes, while a high local expression of the immunoregulatory enzyme indolamine 2, 3 dioxgenase (IDO) was observed. The preventive effect of probiotic-pulsed DCs required not only MyD88-, TLR2- and NOD2-dependent signaling but also the induction of CD4+ CD25+ regulatory cells in an IL-10-independent pathway.

CONCLUSIONS/SIGNIFICANCE

Altogether, these results suggest that selected probiotics can stimulate DC regulatory functions by targeting specific pattern-recognition receptors and pathways. The results not only emphasize the role of DCs in probiotic immune interactions, but indicate a possible role in immune-intervention therapy for IBD.

Gut microbiota: mining for therapeutic potential

The resident microbiota of the human intestine exerts a conditioning effect on intestinal homeostasis, delivering regulatory signals to the epithelium and instructing mucosal immune responses. Pattern recognition receptors are key mediators of innate host defense, and in healthy individuals, the mucosal immune system exhibits an exquisitely regulated restrained response to the resident microbiota. However, in genetically susceptible hosts, unrestrained mucosal immune activation in response to local bacterial signals can contribute to the pathogenesis of inflammatory bowel disease. Manipulation of the microbiota to enhance its beneficial components thus represents a potential therapeutic strategy for inflammatory bowel disease. Moreover, the microbiota might be a rich repository of metabolites that can be exploited for therapeutic benefit. Modern molecular techniques are facilitating improved understanding of host-microbe dialogue in health and in several disease processes, including inflammatory bowel disease. It follows that elucidating the molecular mechanisms of host-microbial interactions is now a prerequisite for a "bugs to drugs" program of discovery.

VSL#3 probiotic mixture: a review of its use in chronic inflammatory bowel diseases

VSL#3 (VSL#3) is a high-concentration probiotic preparation of eight live freeze-dried bacterial species that are normal components of the human gastrointestinal microflora, including four strains of lactobacilli (Lactobacillus casei, L. plantarum, L. acidophilus and L. delbrueckii subsp. bulgaricus), three strains of bifidobacteria (Bifidobacterium longum, B. breve and B. infantis) and Streptococcus salivarius subsp. thermophilus. Data from noncomparative trials suggest that VSL#3 has clinical potential in the treatment of active mild to moderate ulcerative colitis and as maintenance therapy for patients with ulcerative colitis in remission. In addition, a randomised, open-label, multicentre trial showed that VSL#3 in combination with low-dose balsalazide (a prodrug of mesalazine [mesalamine; 5-aminosalicylic acid]) was more effective than standard doses of basalazide or mesalazine monotherapy in the treatment of acute mild to moderate ulcerative colitis. Randomised, double-blind, placebo-controlled studies have shown VSL#3 is effective in preventing the onset of acute pouchitis in patients with newly formed surgical pouches, and in maintaining remission following antibacterial treatment of acute pouchitis in patients with a history of refractory or recurrent pouchitis. Treatment guidelines from the US and the UK include VSL#3 as a therapeutic option for the prevention of pouchitis relapse in patients with chronic pouchitis. In general, VSL#3 was well tolerated in clinical trials. Large, well designed, controlled confirmatory clinical trials will further determine the place of VSL#3 in the treatment of ulcerative colitis.

Probiotics and prebiotics in chronic inflammatory bowel diseases

The prokaryotic and eukaryotic cells of the colon exist in a highly complex, but harmonious relationship. Disturbances in this remarkable symbiosis can result in the development of inflammatory bowel diseases (IBD). Although the etiology of IBD is not entirely understood, it is known that the chronic inflammation of Crohn’s disease, ulcerative colitis and chronic pouchitis are a result of an overly aggressive immune response to the commensal intestinal flora in genetically susceptible hosts. Recent studies have enhanced our ability to understand the interaction between the host and its intestinal microflora and the role the microflora plays in maintaining intestinal homeostasis. As we begin to understand the benefits conferred to the intestine by the microflora, the notion of modifying the composition of the bacterial load to improve human health has arisen. A significant body of research now exists investigating the role of probiotics and prebiotics in ameliorating chronic intestinal inflammation. This article will begin with an overview of the role of the commensal microflora in maintaining mucosal immune homeostasis, and how a dysregulated immune response to the intestinal microflora results in IBD. This will be followed by a summary of the use of probiotics and prebiotics in experimental and human IBD.

Escherichia coli strain Nissle 1917 ameliorates experimental colitis via toll-like receptor 2- and toll-like receptor 4-dependent pathways

Toll-like receptors (TLRs) are key components of the innate immune system that trigger antimicrobial host defense responses. The aim of the present study was to analyze the effects of probiotic Escherichia coli Nissle strain 1917 in experimental colitis induced in TLR-2 and TLR-4 knockout mice. Colitis was induced in wild-type (wt), TLR-2 knockout, and TLR-4 knockout mice via administration of 5% dextran sodium sulfate (DSS). Mice were treated with either 0.9% NaCl or 10(7) E. coli Nissle 1917 twice daily, followed by the determination of disease activity, mucosal damage, and cytokine secretion. wt and TLR-2 knockout mice exposed to DSS developed acute colitis, whereas TLR-4 knockout mice developed significantly less inflammation. In wt mice, but not TLR-2 or TLR-4 knockout mice, E. coli Nissle 1917 ameliorated colitis and decreased proinflammatory cytokine secretion. In TLR-2 knockout mice a selective reduction of gamma interferon secretion was observed after E. coli Nissle 1917 treatment. In TLR-4 knockout mice, cytokine secretion was almost undetectable and not modulated by E. coli Nissle 1917, indicating that TLR-4 knockout mice do not develop colitis similar to the wt mice. Coculture of E. coli Nissle 1917 and human T cells increased TLR-2 and TLR-4 protein expression in T cells and increased NF-kappaB activity via TLR-2 and TLR-4. In conclusion, our data provide evidence that E. coli Nissle 1917 ameliorates experimental induced colitis in mice via TLR-2- and TLR-4-dependent pathways.

Functional modulation of human intestinal epithelial cell responses by Bifidobacterium infantis and Lactobacillus salivarius

Intestinal epithelial cells (IECs) and dendritic cells (DCs) play a pivotal role in antigen sampling and the maintenance of gut homeostasis. However, the interaction of commensal bacteria with the intestinal surface remains incompletely understood. Here we investigated immune cell responses to commensal and pathogenic bacteria. HT-29 human IECs were incubated with Bifidobacterium infantis 35624, Lactobacillus salivarius UCC118 or Salmonella typhimurium UK1 for varying times, or were pretreated with a probiotic for 2 hr prior to stimulation with S. typhimurium or flagellin. Gene arrays were used to examine inflammatory gene expression. Nuclear factor (NF)-kappaB activation, interleukin (IL)-8 secretion, pathogen adherence to IECs, and mucin-3 (MUC3) and E-cadherin gene expression were assayed by TransAM assay, enzyme-linked immunosorbent assay (ELISA), fluorescence, and real-time reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. IL-10 and tumour necrosis factor (TNF)-alpha secretion by bacteria-treated peripheral blood-derived DCs were measured using ELISA. S. typhimurium increased expression of 36 of the 847 immune-related genes assayed, including NF-kappaB and IL-8. The commensal bacteria did not alter expression levels of any of the 847 genes. However, B. infantis and L. salivarius attenuated both IL-8 secretion at baseline and S. typhimurium-induced pro-inflammatory responses. B. infantis also limited flagellin-induced IL-8 protein secretion. The commensal bacteria did not increase MUC3or E-cadherin expression, or interfere with pathogen binding to HT-29 cells, but they did stimulate IL-10 and TNF-alpha secretion by DCs. The data demonstrate that, although the intestinal epithelium is immunologically quiescent when it encounters B. infantis or L. salivarius, these commensal bacteria exert immunomodulatory effects on intestinal immune cells that mediate host responses to flagellin and enteric pathogens.

Postoperative maintenance therapy for inflammatory bowel disease

PURPOSE OF REVIEW

This review will highlight the knowledge gained from studies published in the year 2005 on maintenance treatment after surgery for inflammatory bowel diseases.

RECENT FINDINGS

In Crohn's disease the role of smoking in increasing the risk of relapse and recurrence after surgery is confirmed. Ornidazole seems effective in reducing endoscopic recurrence and clinical relapse after surgery. Probiotics do not appear to be effective in preventing endoscopic recurrence and clinical relapse: a controlled placebo trial showed that Lactobacillus johnsonii is not effective in preventing endoscopic recurrence. A retrospective study suggested that enteral nutrition after surgery may reduce the clinical relapse. Pathophysiological studies underlined the value of probiotics in pouchitis.

SUMMARY

In Crohn's disease postoperative maintenance treatment is disappointing. Giving up smoking is still the only effective measure. Mesalamine remains the drug that has been widely studied with large trials and meta-analysis. Encouraging results come from small trials on antibiotics. Azathioprine and 6-mercaptopurine must be evaluated in better designed controlled trials. There is no evidence in favour of probiotics as an effective therapy to prevent recurrence. Enteral nutrition after surgery is a candidate new therapy, but further controlled trials are needed. Pathophysiological studies confirm the beneficial role of probiotics in pouchitis.

Role of interleukin (IL-10) in probiotic-mediated immune modulation: an assessment in wild-type and IL-10 knock-out mice

While the impact of Bifidobacterium infantis 35624 and other probiotics on cytokines has been shown in established colitis, the effects of B. infantis consumption in pre-inflammation of interleukin (IL)-10 knock-out (KO) mice and on the wild-type (WT) C57Bl/6 mice have not been well demonstrated. The objective of this study was to examine cytokine responses in mucosal and systemic lymphoid compartments of IL-10 KO mice early in disease and to compare with control WT mice. Mice were fed B. infantis or placebo for 5 weeks and culled prior to the onset of chronic intestinal inflammation (12-14 weeks). The spleen, Peyer's patches and intestinal mucosa were removed and stimulated with various bacterial stimuli. Cytokine levels were measured by enzyme-linked immunosorbent assay. While basal intestinal and systemic cytokine profiles of WT and IL-10 KO mice were similar, transforming growth factor (TGF)-beta was reduced in the spleen of IL-10 KO mice. Following probiotic consumption, interferon (IFN)-gamma was reduced in the Peyer's patch of both WT and IL-10 KO mice. Alterations in IFN-gamma in the Peyer's patches of WT mice (enhancement) versus IL-10 KO (reduction) were observed following in vitro stimulation with salmonella. Differential IL-12p40, CCL2 and CCL5 responses were also observed in IL-10 KO mice and WT mice. The cytokine profile of IL-10 KO mice in early disease was similar to that of WT mice. The most pronounced changes occurred in the Peyer's patch of IL-10 KO mice, suggesting a probiotic mechanism of action independent of IL-10. This study provides a rationale for the use of B. infantis 35624 for the treatment of gastrointestinal inflammation.

An approach to analyze mechanisms of intestinal adaptation following total proctocolectomy

We hypothesized that epithelial cells of the remnant small intestine display "colonic" phenotype after total proctocolectomy. The aims of the present study were to identify preferentially expressed molecules in the colon or in the small intestine and to evaluate mRNA levels of those in the ileal pouch. Differential gene expression was investigated between the small intestine and the colon by using cDNA microarray and was confirmed by Northern blotting. Expression of three colonic mRNAs (3-hydroxy-3-methylglutaryl-coenzyme A synthase 2, deleted malignant brain tumors 1, carcinoembryonic antigen-related cell adhesion molecule 1) and one "small intestinal" (microsomal triglyceride transfer protein) mRNA were compared between the control and the ileal pouch mucosae by quantitative reverse transcriptase-polymerase chain reaction. Seventy-four clones were differentially expressed with more than a threefold difference. Differential expression was confirmed in all mRNAs examined, including 3-hydroxy-3-methylglutaryl-coenzyme A synthase 2 and microsomal triglyceride transfer protein. The mucosal expression of carcinoembryonic antigen-related cell adhesion molecule 1 mRNA in the ileal pouch was enhanced in humans. The remnant ileum develops some, but not all, colonic phenotype after total proctocolectomy. Comparative study of epithelial gene expression between the small intestine and the colon enables us to analyze mechanisms of intestinal adaptation after total proctocolectomy.

Probiotics and irritable bowel syndrome: rationale, putative mechanisms, and evidence of clinical efficacy

The irritable bowel syndrome (IBS) follows an acute, presumably infectious diarrheal illness in approximately 15% of patients. There may be a persistent, mild inflammatory state with changes in mucosal function or structure. Changes in the colonic bacterial flora reported in IBS seem related to predominant bowel. Colonic bacteria normally metabolize nutrients with the formation of gas and short chain fatty acids. The latter may induce propulsive contractions and accelerate colonic transit or they may enhance fluid and sodium absorption in the colon. This review addresses the mechanisms, rationale and current evidence for the efficacy of probiotics, including Lactobacilli, Bifidobacteria, and VSL#3, in the treatment of IBS. The mechanisms influenced by probiotics include immune function, motility, and the intraluminal milieu. Probiotics may suppress the low-grade inflammation associated with IBS or restore normal local immune function. Lactobacilli and Bifidobacteria subspecies are able to deconjugate and absorb bile acids, potentially reducing the colonic mucosal secretion of mucin and fluids that may contribute to functional diarrhea or IBS with diarrhea. Therapeutic trials show the potential benefit of Bifidobacteria or Lactobacilli species alone or in the specific probiotic combination, VSL#3, on symptoms in IBS. Colonic transit was retarded in IBS patients treated with VSL#3 without induction of significant changes in bowel function. In summary, probiotics are promising therapies in IBS.