Expression of cytokines, inducible nitric oxide synthase, and matrix metalloproteinases in pouchitis: effects of probiotic treatment

Pouchitis: lessons for inflammatory bowel disease

PURPOSE OF REVIEW

One of the significant limitations to the investigation of inflammatory bowel disease (IBD) in humans is the impossibility of studying this condition from the beginning of the disease process to understand the individual contribution of the various microbiological and immunological components to its pathogenesis. Pouchitis can serve as a human model for IBD, as the time of the pouch creation is known, which allows to prospectively study the events that might eventually lead to the development of a form of intestinal inflammation (i.e., pouchitis) that mimics IBD.

RECENT FINDINGS

A considerable amount of progress has been made in the last few years on the mechanisms underlying the pathogenesis of pouchitis. Recent literature suggests that pouchitis may present a spectrum of disease processes, with a wide range of causes, risk factors, clinical phenotypes, disease courses, and prognoses. Genetic, microbiological, and immunological profiles in pouchitis were evaluated.

SUMMARY

Ileal pouch and pouchitis represent a valuable human model to study the evolution of bacterial communities and host-bacteria interactions in IBD by sequentially monitoring microbiological and immunological profile before, during, and after pouch construction and before and after development and treatment of pouchitis.

Probiotics reduce the inflammatory response induced by a high-fat diet in the liver of young rats

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease in the pediatric population. Preliminary evidence suggests a potential therapeutic utility of probiotics for this condition. Here, we tested the potential effect of the probiotic VSL#3 (a multistrain preparation composed of Streptococcus thermophilus and several species of Lactobacillus and Bifidobacteria) on oxidative and inflammatory damage induced by a high-fat diet in the liver of young rats. At weaning, young male Sprague-Dawley rats were randomly divided into 3 groups (n = 6) fed a standard, nonpurified diet (Std; 5.5% of energy from fat) or a high-fat liquid diet (HFD; 71% of energy from fat). One of the HFD groups received by gavage VSL#3 (13 x 10(9) bacteria x kg(-1) x d(-1)). After 4 wk, the HFD rats had greater body weight gain, fat mass, serum aminotransferase, and liver weight than rats fed the Std diet. The HFD induced liver lipid peroxidation, tumor necrosis factor (TNFalpha) production, protein S-nitrosylation, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 expression, and metalloproteinase (MMP) activity. Moreover, in the HFD group, PPARalpha expression was less than in rats fed the Std diet. In rats fed the HFD diet and treated with VSL#3, liver TNFalpha levels, MMP-2 and MMP-9 activities, and expression of iNOS and COX-2 were significantly lower than in the HFD group. In VSL#3-treated rats, PPARalpha expression was greater than in the HFD group. A modulation of the nuclear factor-kappaB pathway by VSL#3 was also demonstrated. Our data suggest that VSL#3 administration could limit oxidative and inflammatory liver damage in patients with NAFLD.

Effects of Lactobacillus plant arum on genes expression pattern in mice jejunal Peyer's patches

Jejunal Peyer's patches contain specialized epithelial M cells that take up ingested microorganisms from the lumen of the gut by transcytosis. Using DNA-micro array, we analyzed the gene expression patterns of jejunal Peyer's patches in order to gain insight into the molecular mechanism by which Lp6 interacted with the host organism in a gnotobiotic environment v. in the gut normal microflora. The micro array data revealed that, among approximately 14,000 genes, 420 were expressed in Lp6 administration group at twofold or higher levels compared to the control group. These included genes involved in immune response, and cell differentiation, cell-cell signaling, cell adhesion, signal transcription, and transduction. Real-time PCR confirmed the reliability of the analysis. These data indicated that administration of Lactobacillus Lp6 was associated with a complex genetic response in the jejunal Peyer's patches.

Probiotics and immunity

Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, including the gastrointestinal tract. While this beneficial effect was originally thought to stem from improvements in the intestinal microbial balance, there is now substantial evidence that probiotics can also provide benefits by modulating immune functions. In animal models, probiotic supplementation is able to provide protection from spontaneous and chemically induced colitis by downregulating inflammatory cytokines or inducing regulatory mechanisms in a strain-specific manner. In animal models of allergen sensitization and murine models of asthma and allergic rhinitis, orally administered probiotics can strain-dependently decrease allergen-specific IgE production, in part by modulating systemic cytokine production. Certain probiotics have been shown to decrease airway hyperresponsiveness and inflammation by inducing regulatory mechanisms. Promising results have been obtained with probiotics in the treatment of human inflammatory diseases of the intestine and in the prevention and treatment of atopic eczema in neonates and infants. However, the findings are too variable to allow firm conclusions as to the effectiveness of specific probiotics in these conditions.

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 action of probiotics: recent advances

The intestinal microbiota plays a fundamental role in maintaining immune homeostasis. In controlled clinical trials probiotic bacteria have demonstrated a benefit in treating gastrointestinal diseases, including infectious diarrhea in children, recurrent Clostridium difficile-induced infection, and some inflammatory bowel diseases. This evidence has led to the proof of principle that probiotic bacteria can be used as a therapeutic strategy to ameliorate human diseases. The precise mechanisms influencing the crosstalk between the microbe and the host remain unclear but there is growing evidence to suggest that the functioning of the immune system at both a systemic and a mucosal level can be modulated by bacteria in the gut. Recent compelling evidence has demonstrated that manipulating the microbiota can influence the host. Several new mechanisms by which probiotics exert their beneficial effects have been identified and it is now clear that significant differences exist between different probiotic bacterial species and strains; organisms need to be selected in a more rational manner to treat disease. Mechanisms contributing to altered immune function in vivo induced by probiotic bacteria may include modulation of the microbiota itself, improved barrier function with consequent reduction in immune exposure to microbiota, and direct effects of bacteria on different epithelial and immune cell types. These effects are discussed with an emphasis on those organisms that have been used to treat human inflammatory bowel diseases in controlled clinical trials.

Pouchitis: an evolving clinical enigma--a review

While the overall incidence of pouchitis is low, extensive research continues at clinical and experimental levels in attempts to unravel its etiology. The ileal pouch and pouchitis together represent a unique in vivo opportunity to study mucosal adaptation and inflammation in depth. In the recent past, molecular data relating to pouchitis has significantly expanded. These data provide invaluable insight into intracellular and extracellular events that underpin mucosal adaptation and inflammation. Advances in classification, risk factor evaluation, and prevention have meant that a review of this data, as well as its relationship to our current understanding of pouchitis, is both timely and warranted. Therefore, the aim of this review is to summarize recent data in the context of the established literature.

Rationale for probiotic treatment strategies in inflammatory bowel disease

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

On the benefit of probiotics in the management of pouchitis in patients underwent ileal pouch anal anastomosis: a meta-analysis of controlled clinical trials

The objective of this study was to evaluate and collect current evidence on the effect of probiotics in preventing pouchitis after restorative ileal pouch anal anastomosis (IPAA). The Pubmed, Medline, EMbase, CINAHL, Web of Science, and Scopus bibliographic, and Google Scholar databases were searched between 1966 and May 2007, and relevant controlled clinical trials were extracted, reviewed, and validated according to the study protocol. The outcome of interest was for pouchitis defined by a pouchitis disease activity index (PDAI) > or =7. Five randomized, placebo-controlled clinical trials were included in the meta-analysis. Pooling of the results from these trials yielded an odds ratio (OR) of 0.04 with a 95% CI of 0.01-0.14 (P < 0.0001) in the treatment group in comparison with the placebo group. In conclusion, the benefit of probiotics in the management of pouchitis after IPAA operation was confirmed by the meta-analysis.

Probiotic lactobacilli and VSL#3 induce enterocyte beta-defensin 2

Recent evidence suggests that probiotic bacteria may stabilize gut barrier function via induction of anti-microbial peptides such as defensins. This study aimed to elucidate the induction mechanism of the human beta defensin-2 (hBD-2) gene by different probiotic lactobacillus strains. The expression of hBD-2 mRNA peaked at 6 h of incubation upon treatment of Caco-2 cells and increased with higher dosage of various probiotic bacteria. Deletion of nuclear factor (NF)-kappaB and activator protein-1 (AP-1) binding sites on the hBD-2 promoter resulted in a complete abrogation of promoter activation by probiotics. As revealed by the use of specific mitogen-activated protein kinase (MAPK) inhibitors the hBD-2 induction was dependent on the MAPK extracellular regulated kinase (ERK 1/2), p38 and c-Jun N-terminal kinase (JNK), although to varying degrees. Several Lactobacillus strains and VSL#3, a probiotic cocktail of four lactobacilli, three bifidum and one streptococcus species, induced the secretion of the hBD-2 peptide into the culture media as shown by enzyme-linked immunosorbent assay (ELISA). Thus, the present study suggests that lactobacilli and the VSL#3 bacterial mixture strengthen intestinal barrier functions through the up-regulation of hBD-2 via induction of proinflammatory pathways including NF-kappaB and AP-1 as well as MAPKs.

The novel porcine Lactobacillus sobrius strain protects intestinal cells from enterotoxigenic Escherichia coli K88 infection and prevents membrane barrier damage

Lactobacilli have a potential to overcome intestinal disorders; however, the exact mode of action is still largely unknown. In this study, we have used the intestinal porcine intestinal IPEC-1 epithelial cells as a model to investigate a possible protective activity of a new Lactobacillus species, the L. sobrius DSM 16698(T), against intestinal injury induced by enterotoxigenic Escherichia coli (ETEC) K88 infection and the underlying mechanisms. Treatment of infected cells with L. sobrius strongly reduced the pathogen adhesion. L. sobrius was also able to prevent the ETEC-induced membrane damage by inhibiting delocalization of zonula occludens (ZO)-1, reduction of occludin amount, rearrangement of F-actin, and dephosphorylation of occludin caused by ETEC. RT-PCR and ELISA experiments showed that L. sobrius counteracted the ETEC-induced increase of IL-8 and upregulated the IL-10 expression. The involvement of IL-8 in the deleterious effects of ETEC was proven by neutralization of IL-8 with a specific antibody. A crucial role of IL-10 was indicated by blockage of IL-10 production with neutralizing anti-IL-10 antibody that fully abrogated the L. sobrius protection. L. sobrius was also able to inhibit the internalization of ETEC, which was likely favored by the leaking barrier. The protective effects were not found with L. amylovorus DSM 20531(T) treatment, a strain derived from cattle waste but phylogenetically closely related to L. sobrius. Together, the data indicate that L. sobrius exerts protection against the harmful effects of ETEC by different mechanisms, including pathogen adhesion inhibition and maintenance of membrane barrier integrity through IL-10 regulation.

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.

Identification of a signalling molecule involved in bacterial intergeneric communication

The development of complex multispecies communities such as biofilms is controlled by interbacterial communication systems. We have previously reported an intergeneric communication between two oral bacteria, Streptococcus cristatus and Porphyromonas gingivalis, that results in inhibition of fimA expression. Here, we demonstrate that a surface protein, arginine deiminase (ArcA), of S. cristatus serves as a signal that initiates intergeneric communication. An ArcA-deficient mutant of S. cristatus is unable to communicate with P. gingivalis. Furthermore, arginase activity is not essential for the communication, and ArcA retains the ability to repress expression of fimA in the presence of arginine deiminase inhibitors. These results present a novel mechanism by which intergeneric communication in dental biofilms is accomplished.

Pouchitis

While restorative proctocolectomy with ileal pouch-anal anastomosis has significantly improved the quality of life in patients with underlying ulcerative colitis who require surgery, complications can occur. Pouchitis as the most common long-term complication represents a spectrum of disease processes ranging from acute, antibiotic-responsive type to chronic antibiotic-refractory entity. Accurate diagnosis using a combined assessment of symptoms, endoscopy and histology and the stratification of clinical phenotypes is important for treatment and prognosis the disease. The majority of patients respond favorably to antibiotic therapy. However, management of chronic antibiotic-refractory pouchitis remains a challenge.

Balsalazide and/or high-potency probiotic mixture (VSL#3) in maintaining remission after attack of acute, uncomplicated diverticulitis of the colon

BACKGROUND AND AIMS

The role of probiotics in the treatment of diverticulitis is still not known. The aim of our study was to investigate whether balsalazide and/or VSL#3 is effective in preventing diverticulitis recurrence.

MATERIALS AND METHODS

In this pilot study, 30 consecutive patients (19 males, 11 females, mean age 60.1 years, range 47-75 years) affected by uncomplicated diverticulitis of the colon were monitored. After obtaining remission, the patients were randomly assigned to one of the following groups as follows: group A, balsalazide 2.25 g daily for 10 days every month plus VSL#3 450 billions/day for 15 days every month and group B, VSL#3 alone 450 billions/day for 15 days every month. Primary end-point was considered the maintaining of remission throughout a 12-month follow-up. Secondary end-points considered were (1) the assessment of the overall scores at the end of the follow-up and (2) the effects of the two different treatments with regards to every symptom assessed.

RESULTS/FINDINGS

One group A patient was withdrawn from the study at the 6th month and one group B patient was lost at the 6th month of follow-up. One group A patient (6.66%) showed relapse of symptoms at the 10th month of follow-up. At the end of follow-up, 11 patients were completely symptom-free (73.33%), whilst 2 patients complained of only mild, recurrent symptoms (13%). Two group B patients (13.33%) showed relapse of the disease at the 5th and 8th month of follow-up, respectively. At the end of follow-up, 8 patients were completely symptom-free (60%), 2 patients complained of mild, recurrent symptoms (13.33%), 1 patient (6.66%) complained of mild but continuous symptoms. No side effects were recorded throughout the follow-up in both groups.

INTERPRETATION/CONCLUSIONS

Combination probiotic/anti-inflammatory drug was found better than probiotic treatment in preventing relapse of uncomplicated diverticulitis of the colon, even if without statistical significance.

Ileal pelvic pouch microbiota from two former ulcerative colitis patients, analysed by DNA-based methods, were unstable over time and showed the presence of Clostridium perfringens

OBJECTIVE

Ileal pouch anal anastomosis (IPAA) is the preferred method for restorative surgery in patients with ulcerative colitis who have to undergo proctocolectomy. The most common complication is pouchitis and several studies have pointed to the microbiota of the pouch as being a risk factor. The aim of this study was to follow the development of the bacterial microbiota in pouches during the first year.

MATERIAL AND METHODS

Terminal restriction fragment length polymorphism (T-RFLP) combined with cloning and sequencing was used to identify the most predominant bacteria on the different sampling occasions. A total of 274 clones were grouped by T-RFLP and clones from each group were selected for sequencing and identified by comparison with known sequences.

RESULTS

Differences in T-RFLP profiles and clone libraries were found between the patients, and also in changes apparent in each patient at different time-points. The main bacterial groups in the pouches resembled those of the normal colonic microbiota, with a predominance of the clostridia clusters XIVa and IV, Bacteroides and Enterobacteriaceae. Exceptions were clones with sequences resembling those of the Clostridium perfringens group, in both patients and on all sampling occasions, and the dominance of clones resembling Turicibacter in one of the patients at the time of pouch construction.

CONCLUSIONS

The pouch microbiota showed similarities to the normal colon microbiota except for the presence of clones with sequences resembling those of the C. perfringens group and Turicibacter. The bacterial composition differed between the two patients and the microbiota changed with time, suggesting that the composition is not stable during the first year.

Design of a multispecies probiotic mixture to prevent infectious complications in critically ill patients

BACKGROUND & AIMS

Although the potential for probiotics is investigated in an increasing variety of diseases, there is little or no consensus regarding the desired probiotic properties for a particular disease in question, nor about the final design of the probiotic. Specific strain selection procedures were undertaken to design a disease-specific multispecies probiotic.

METHODS

From a strain collection of 69 different lactic acid bacteria a primary selection was made of 14 strains belonging to different species showing superior survival in a simulated gastrointestinal environment. Functional tests like antimicrobial activity against a range of clinical isolates and cytokine inducing capacity in cultured human peripheral blood mononuclear cells were used to further identify potential strains.

RESULTS

Specific strains inhibited growth of clinical isolates whereas others superiorly induced the anti-inflammatory cytokine IL-10. Based on functional tests and general criteria regarding probiotic design and safety, a selection of the following six strains was made (Ecologic 641); Bifidobacterium bifidum, Bifidobacterium infantis, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus salivarius and Lactococcus lactis. Combination of these strains resulted in a wider antimicrobial spectrum, superior induction of IL-10 and silencing of pro-inflammatory cytokines as compared to the individual components.

CONCLUSIONS

Application of strict criteria during the design of a disease-specific probiotic prior to implementation in clinical trials may provide a rational basis for use of probiotics.

Dysbiosis in pouchitis: evidence of unique microfloral patterns in pouch inflammation

BACKGROUND & AIMS

Pouch inflammation after surgery for ulcerative colitis can significantly alter quality of life and thus ideally should be prevented. Dysbiosis or altered microflora is suspected to be the key pathogenic factor for pouchitis. However, dysbiosis in pouchitis has not been characterized carefully because of a lack of available sensitive microbiological technology suitable for in vivo studies in human beings. Thus, the aims of our study were as follows: (1) to show the use of the length heterogeneity polymerase chain reaction (LH-PCR) technique for studying microflora in human beings, and (2) to use the technique to characterize the microfloral patterns in the ileal pouch of patients with pouchitis.

METHODS

Microfloral patterns initially were assessed using a 16S ribosomal RNA technique (LH-PCR) to determine the qualitative changes in the luminal and mucosal intestinal flora. We subsequently cloned and sequenced the LH-PCR amplification products from the community 16S ribosomal RNA found in patients with pouchitis and in control pouch to identify the microbial species involved in pouchitis.

RESULTS

We have shown unique microfloral patterns in pouchitis. Through cloning and sequencing of the LH-PCR amplicons, we have shown the persistence of Fusobacter and Enteric species associated with the disease state and the absence of specific bacteria such as Streptococcus species in the inflamed pouch.

CONCLUSIONS

We have shown that the LH-PCR technique is suitable for studying microflora in human beings. By using this technique and the clone sequences, we have shown dysbiosis in the microbial biofilm adherent to the mucosa in pouchitis. Our data provide direct evidence of the role of bacteria in the pathogenesis of pouchitis.

Saccharomyces boulardii inhibits inflammatory bowel disease by trapping T cells in mesenteric lymph nodes

BACKGROUND & AIMS

Saccharomyces boulardii is a nonpathogenic yeast used for treatment of diarrhea. We used a mice model of inflammatory bowel disease (IBD) to analyze the effects of S boulardii on inflammation.

METHODS

Lymphocyte-transferred SCID mice, displaying IBD, were fed daily with S boulardii. Weight loss and inflammatory status of the colon were monitored. Nuclear factor-kappaB activity was assessed in the colon. The CD4(+) T-cell production of interferon (IFN) gamma was evaluated by enzyme-linked immunosorbent assay, and a comprehensive reverse-transcription polymerase chain reaction (RT-PCR) analysis for both colon and mesenteric lymph nodes was performed. Finally, we analyzed cell migration mechanisms in vitro and in vivo.

RESULTS

S boulardii treatment inhibits IBD. S boulardii induces an accumulation of IFN-gamma-producing T-helper 1 cells within the mesenteric lymph nodes correlated with a diminution of CD4(+) T-cell number and IFN-gamma production by CD4+ T cells within the colon. The influence of S boulardii treatment on cell accumulation in mesenteric lymph nodes was also observed in normal BALB/c mice and involves modifications of lymph node endothelial cell adhesiveness by a yeast secretion product.

CONCLUSIONS

S boulardii has a unique action on inflammation by a specific alteration of the migratory behavior of T cells, which accumulate in mesenteric lymph nodes. Therefore, S boulardii treatment limits the infiltration of T-helper 1 cells in the inflammed colon and the amplification of inflammation induced by proinflammatory cytokines production. These results suggest that S boulardii administration may have a beneficial effect in the treatment of IBD.

Lactobacillus fermentum, a probiotic capable to release glutathione, prevents colonic inflammation in the TNBS model of rat colitis

BACKGROUND AND AIMS

Inflammatory bowel disease is associated with intestinal oxidative stress. In the present study we test the preventative effect of Lactobacillus fermentum, a probiotic that produces per se glutathione, in the trinitrobenzenesulphonic acid (TNBS) model of rat colitis.

METHODS

Colitis was induced in rats by intracolonic administration of 10 mg of TNBS dissolved in 0.25 ml of 50% ethanol. L. fermentum was administered orally (5x10(8) CFU suspended in 0.5 ml of skim milk) to a group of rats for 3 weeks, starting 2 weeks before colitis induction. Colonic damage was evaluated both histologically and biochemically, and the colonic luminal contents were used for bacterial studies as well as for short chain fatty acid (SCFA) production.

RESULTS

L. fermentum treatment resulted in an amelioration of the inflammatory response in colitic rats as evidenced histologically and by a significant reduction of colonic MPO activity (P<0.05). The probiotic partially counteracted the colonic glutathione depletion induced by the inflammatory process. In addition, probiotic-treated colitic rats showed significant lower colonic tumour necrosis factor (TNF)alpha levels (P<0.01) and inducible nitric oxide synthase (iNOS) expression when compared to non-treated rats. Finally, the probiotic induced growth of Lactobacilli species and production of SCFA in colonic contents in comparison with control colitic rats.

CONCLUSION

Administration of the probiotic L. fermentum facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an effect associated with increased levels of glutathione as well as with amelioration of the production of some of the mediators involved in the inflammatory response of the intestine, such as TNFalpha and NO.

Probiotics and inflammatory bowel diseases

Enteric microflora profiles vary considerably between active inflammatory bowel diseases (IBD) and healthy conditions. Intestinal microflora may partake in the pathogenesis of IBD by one or some ways: specific pathogenic infection induces abnormal intestinal mucosal inflammation; aberrant microflora components trigger the onset of IBD; abnormal host immune response loses normal immune tolerance to luminal components; luminal antigens permeate through the defective mucosal barrier into mucosal lamina propria and induce abnormal inflammatory response. Preliminary studies suggest that administration of probiotics may be benefit for experimental colitis and clinical trials for IBD. Researches have been studying the function of probiotics. Introduction of probiotics can balance the aberrant enteric microflora in IBD patients, and reinforce the various lines of intestinal defence by inhibiting microbial pathogens growth, increasing intestinal epithelial tight junction and permeability, modulating immune response of intestinal epithelia and mucosal immune cells, secreting antimicrobial products, decomposing luminal pathogenic antigens.

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.

Lactobacilli, bifidobacteria and E. coli nissle induce pro- and anti-inflammatory cytokines in peripheral blood mononuclear cells

AIM: To investigate whether the stimulation of peripheral blood mononuclear cells (PBMNC) with the cell debris and cell extraction of different probiotic strains is similar or species specific.

METHODS: Three strains of bifidobacteria, 4 strains of lactobacilli, and E. coli nissle were sonicated and centrifuged in order to divide them into cell extract and cell debris. PBMNC were separated by density gradient and incubated for 36 h with either the cell debris or the cell extract of single strains of probiotic bacteria in doses from 10² to 10⁸ CFU/mL. Cell supernatants were taken and interleukin (IL)-10, IL-1β, and tumor necosis factor (TNF)-α were determined by ELISA.

RESULTS: Depending on the species super-family, the strains had different stimulation patterns. Except for both L. casei strains, the cell extract of bifidobacteria and lactobacilli had less stimulating capacity than cell debris, whereas the cell extract of E. coli nissle had similar stimulating properties to that of the cell debris of the strain and significantly more stimulating capacity than that of bifidobacteria and lactobacilli. The cell debris of bifidobacteria stimulated more cytokine release than the cell debris of lactobacilli. The cell debris of lactobacilli did not have a stimulating capacity when lower concentrations were used. Neither cell extraction nor cell debris had an inhibitory effect on the production of the tested cytokines by stimulated PBMNC.

CONCLUSION: The incubation of probiotic strains, which have been used in clinical trials for inflammatory diseases, with immunocompetent cells leads to different species specific reactions. High IL-10 response to cell debris of bifidobacteria and E. coli nissle can be found. This corresponds to positive effects of bifidobacteria and E. coli nissle in clinical trials for inflammatory bowel disease compared to negative outcomes obtained with lactobacilli.

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.

Effects of probiotics on radiation-induced intestinal injury in rats

OBJECTIVE

Radiotherapy is an important aspect of multimodal cancer therapy, but radiation-induced acute intestinal injury is a common and serious problem. Disruption of morphologic mucosal integrity and normal bacterial microflora after abdominal radiation leads to malabsorption and bacterial translocation.

METHODS

Lactobacillus bulgaricus strain isolated from yogurt was given as a probiotic to rats subjected to radiotherapy. On postradiation day 8 rats were killed. Mesenteric lymph nodes, liver, and spleen were excised for microbiologic examinations. Segments of jejunum, ileum, and colon were evaluated for the presence of inflammation, vascularity, and mucus cells.

RESULTS

The results of this study suggest that probiotics may have a protective effect on intestinal mucosa.

CONCLUSION

Probiotics added as substrates can be given by an oral or enteral route to patients who undergo radiotherapy to prevent radiation-induced enteritis and related malnutrition.

Antibiotics and probiotics in treatment of inflammatory bowel disease

Many experimental and clinical observations suggest that intestinal microflora plays a potential role in the pathogenesis of inflammatory bowel disease (IBD). Manipulation of the luminal content using antibiotics or probiotics represents a potentially effective therapeutic option. The available studies do not support the use of antibiotics in ulcerative colitis (UC). Antibiotics are effective in treating septic complications of Crohn’s disease (CD) but their use as a primary therapy is more controversial, although this approach is frequently and successfully adopted in clinical practice.

There is evidence that probiotic therapy may be effective in the prevention and treatment of mild to moderate UC. In contrast, a lack of successful study data at present precludes the widespread use of probiotics in the treatment of CD.

Both antibiotics and probiotics appear to play a beneficial role in the treatment and prevention of pouchitis and further trials are warranted to fully quantify their clinical efficacy.

The VSL# 3 probiotic mixture modifies microflora but does not heal chronic dextran-sodium sulfate-induced colitis or reinforce the mucus barrier in mice

The mucus layer covering the epithelium is one of the main lines of defense of the colonic barrier. Both mucus gel and mucin expressions are altered during colonic inflammation and could be involved in epithelial repair. We postulated that modulating colonic mucus and mucins by probiotic supplementation could contribute to healing inflammatory mucosa. Our aim in this study was to determine whether probiotics could repair dextran-sodium sulfate (DSS)-induced chronic colitis in mice, and whether modifications of the colonic mucins could be involved. For that purpose, the VSL#3 probiotic mixture of 8 lactic acid bacteria probiotic strains was administered daily for 2 wk to mice with a mucosa impaired by a mild DSS treatment, and to mice with a normal mucosa. Probiotic strains survived in the gastrointestinal tract, increased the cecal concentrations of bifidobacteria, and modified cecal microflora metabolic activity in both DSS-treated and healthy mice. However, probiotic supplementation did not reverse the inflammation induced by DSS at either the macroscopic or histological level. Concurrently, probiotics did not modify the colonic mucus barrier, in terms of either mucin gene expression or adherent mucus layer thickness. In conclusion, the modification of microflora by supplementation with the VSL#3 probiotic mixture did not help to repair the colonic barrier breakdown caused by DSS treatment. The potential healing roles of mucins were neither confirmed nor invalidated by this study.

Cytokine expression in an ex vivo culture system of duodenal samples from dogs with chronic enteropathies: modulation by probiotic bacteria

There is evidence that probiotics have immune-modulating effects on intestinal inflammation during chronic enteropathies (CE). In an ex vivo culture system we investigated the influence of probiotics on mRNA and protein expression levels of cytokines in intestinal samples from dogs suffering from CE. Duodenal samples of client-owned dogs with CE (group CE; n = 12) were collected during diagnostic endoscopy. Additional duodenal samples of gastrointestinally healthy dogs (group C; n = 4) from an unrelated study were available. Based on histopathological analyses, no pathological changes or only mild to moderate eosinophilic and/or lymphoplasmacytic duodenitis were diagnosed. Tissue samples were cultured: (1) with cell culture medium alone (negative control), (2) with a probiotic cocktail (PC), constituted of three Lactobacilli spp. from healthy canine fecal isolates, (3) with the individual strains of PC, and (4) with a placebo powder. Viability of intestinal tissue and probiotic bacteria before and after culture was evaluated. The mRNA abundance of interleukin (IL)-10, IL-12p40, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta1 was analyzed by real-time polymerase chain reaction (RT-PCR). Protein concentrations of IFN-gamma and IL-10 were measured in culture supernatant by ELISA. Results of RT-PCR were expressed as 2(-2DeltaCrossing Point) x 100 after normalization with beta-actin. There was a loss of about 1 log CFU/mL of probiotic bacteria during the incubation period. Viability of tissue was maintained as confirmed by non-significant release of lactate dehydrogenase. In C, addition of PC increased IL-10 mRNA levels (P < 0.1). In CE, PC increased mRNA and protein levels of IL-10 (P < 0.05). On the mRNA level, the ratio of TNFalpha-/IL-10, IFN-gamma/IL-10, and IL-12p40/IL-10 decreased after addition of PC (P < 0.05). The results demonstrate favorable effects of PC on regulatory cytokines relative to inflammatory cytokines that might contribute to reduction of intestinal inflammation.

Preventative effects of a probiotic, Lactobacillus salivarius ssp. salivarius, in the TNBS model of rat colitis

AIM: To investigate the intestinal anti-inflammatory effect and mechanism of a probiotic Lactobacillus salivarius ssp. salivarius CECT5713 in the TNBS model of rat colitis.

METHODS: Female Wistar rats (180-200 g) were used in this study. A group of rats were administered orally the probiotic L. salivarius ssp. salivarius (5×10⁸ CFU suspended in 0.5 mL of skimmed milk) daily for 3 wk. Two additional groups were used for reference, a non-colitic and a control colitic without probiotic treatment, which received orally the vehicle used to administer the probiotic. Two weeks after starting the experiment, the rats were rendered colitic by intracolonic administration of 10 mg of TNBS dissolved in 0.25 mL of 500 mL/L ethanol. One week after colitis induction, all animals were killed and colonic damage was evaluated both histologically and biochemically. The biochemical studies performed in colonic homogenates include determination of myeloperoxidase (MPO) activity, glutathione (GSH) content, leukotriene B₄ (LTB₄) and tumor necrosis factor α (TNF-α) levels, as well as inducible nitric oxide synthase (iNOS) expression. In addition, the luminal contents obtained from colonic samples were used for microbiological studies, in order to determine Lactobacilli and Bifidobacteria counts.

RESULTS: Treatment of colitic rats with L. salivarius ssp. salivarius resulted in amelioration of the inflammatory response in colitic rats, when compared with the corresponding control group without probiotic treatment. This anti-inflammatory effect was evidenced macroscopically by a significant reduction in the extent of colonic necrosis and/or inflammation induced by the administration of TNBS/ethanol (2.3±0.4 cm vs 3.4±0.3 cm in control group, P<0.01) and histologically by improvement of the colonic architecture associated with a reduction in the neutrophil infiltrate in comparison with non-treated colitic rats. The latter was confirmed biochemically by a significant reduction of colonic MPO activity (105.3±26.0 U/g vs 180.6±21.9 U/g, P<0.05), a marker of neutrophil infiltration. The beneficial effect was associated with an increase of the colonic GSH content (1 252±42 nmol/g vs 1 087±51 nmol/g, P<0.05), which is depleted in colitic rats, as a consequence of the oxidative stress induced by the inflammatory process. In addition, the treatment of colitic rats with L. salivarius resulted in a significant reduction of colonic TNF-α levels (509.4±68.2 pg/g vs 782.9±60.1 pg/g, P<0.01) and in a lower colonic iNOS expression, when compared to TNBS control animals without probiotic administration. Finally, treated colitic rats showed higher counts of Lactobacilli species in colonic contents than control colitic rats, whereas no differences were observed in Bifidobacteria counts.

CONCLUSION: Administration of the probiotic L. salivarius ssp. salivarius CECT5713 facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an effect associated with amelioration of the production of some of the mediators involved in the inflammatory response in the intestine, such as cytokines, including TNF-α and NO. This beneficial effect could be ascribed to its effect on the altered immune response that occurs in this inflammatory condition.

Oral probiotic administration induces interleukin-10 production and prevents spontaneous autoimmune diabetes in the non-obese diabetic mouse

AIMS/HYPOTHESIS

Recent observations suggest the involvement of the gastrointestinal tract in the pathogenesis of islet autoimmunity. Thus, the modulation of gut-associated lymphoid tissue may represent a means to affect the natural history of the disease. Oral administration of probiotic bacteria can modulate local and systemic immune responses; consequently, we investigated the effects of oral administration of the probiotic compound VSL#3 on the occurrence of diabetes in non-obese diabetic (NOD) mice.

METHODS

VSL#3 was administered to female NOD mice three times a week starting from 4 weeks of age. A control group received PBS. Whole blood glucose was measured twice a week. IFN-gamma and IL-10 production/expression was evaluated by ELISA in culture supernatants of mononuclear cells isolated from Peyer's patches and the spleen, and by real-time PCR in the pancreas. Insulitis was characterised by immunohistochemistry and histomorphometric studies.

RESULTS

Early oral administration of VSL#3 prevented diabetes development in NOD mice. Protected mice showed reduced insulitis and a decreased rate of beta cell destruction. Prevention was associated with an increased production of IL-10 from Peyer's patches and the spleen and with increased IL-10 expression in the pancreas, where IL-10-positive islet-infiltrating mononuclear cells were detected. The protective effect of VSL#3 was transferable to irradiated mice receiving diabetogenic cells and splenocytes from VSL#3-treated mice.

CONCLUSIONS/INTERPRETATION

Orally administered VSL#3 prevents autoimmune diabetes and induces immunomodulation by a reduction in insulitis severity. Our results provide a sound rationale for future clinical trials of the primary prevention of type 1 diabetes by oral VSL#3 administration.

Inducible nitric oxide synthase involvement in the mechanism of action of Saccharomyces boulardii in castor oil-induced diarrhoea in rats

The biotherapeutic agent Saccharomyces boulardii has been shown to inhibit castor oil-induced diarrhoea in rats in a dose-response fashion, and one of the suggested mechanisms of action included involvement of the nitric oxide pathway. The present study was designed to address this mechanism of action by firstly measuring the effects of S. boulardii on the inducible nitric oxide synthase (iNOS) isoform activity in vitro. Second, the effects of S. boulardii on the increase in colonic citrulline level associated with castor oil treatment were examined. In vitro, S. boulardii showed a dose-dependent inhibition of iNOS activity with an IC50 of 0.89 mg/ml. In the rat diarrhoea model, the antidiarrhoeal effect of S. boulardii was confirmed using a single oral dose of 12 x 10(10) CFU/kg (viable cells). In this model, castor oil significantly elevated citrulline level from 2526+/-164 to 3501+/-193 nmol/g in the colon. When the rats were treated with the same antidiarrhoeal single dose of S. boulardii, no increase in citrulline level was observed. Moreover, the iNOS inhibitor 1400 W at 10 mg/kg and the inhibitor of iNOS expression dexamethasone at 1 mg/kg, administered subcutaneously, blocked the citrulline production induced by the laxative. Taken together, these findings confirm the involvement of inhibition of the inducible isoform of nitric oxide synthase in the mechanism of action of S. boulardii in diarrhoea.

VSL#3 probiotic-mixture induces remission in patients with active ulcerative colitis

BACKGROUND AND AIMS

Intestinal bacteria have been implicated in the initiation and perpetuation of IBD; in contrast, "probiotic bacteria" have properties possibly effective in treating and preventing relapse of IBD. We evaluated the safety and efficacy of VSL#3 and the components, and the composition of the biopsy-associated microbiota in patients with active mild to moderate ulcerative colitis (UC).

METHODS

Thirty-four ambulatory patients with active UC received open label VSL#3, 3,600 billion bacteria daily in two divided doses for 6 wk. The presence of biopsy-associated bacteria was detected using a nucleic acid-based method and the presence of VSL#3 species confirmed by DNA sequencing of 16S rRNA.

RESULTS

Thirty-two patients completed 6 wk of VSL#3 treatment and 2 patients did not have the final endoscopic assessment. Intent to treat analysis demonstrated remission (UCDAI < or = 2) in 53% (n = 18); response (decrease in UCDAI > or = 3, but final score > or =3) in 24% (n = 8); no response in 9% (n = 3); worsening in 9% (n = 3); and failure to complete the final sigmoidoscopy assessment in 5% (n = 2). There were no biochemical or clinical adverse events related to VSL#3. Two of the components of VSL#3 were detected by PCR/DGGE in biopsies collected from 3 patients in remission.

CONCLUSION

Treatment of patients with mild to moderate UC, not responding to conventional therapy, with VSL#3 resulted in a combined induction of remission/response rate of 77% with no adverse events. At least some of the bacterial species incorporated in the probiotic product reached the target site in amounts that could be detected.

Green fluorescent protein for detection of the probiotic microorganism Escherichia coli strain Nissle 1917 (EcN) in vivo

Probiotic microorganisms are defined as viable nutritional agents conferring benefit to the health of the human host. Especially, Escherichia coli strain Nissle 1917 (EcN) was shown to be equally effective as mesalazine in the maintenance of remission in ulcerative colitis (UC). Presumably, the therapeutic effect of EcN is linked to the presence of the strain in the region of interest; however, it remains difficult to follow the orally administered strain on its passage through the complex microbial environment of the intestine in vivo, inhabited dominantly by various E. coli strains, using traditional culturing methods. In this study we transformed EcN and a wild-type E. coli from a laboratory rat (EcR) with a plasmid carrying a gfp gene (pUC-gfp) to obtain EcN- and EcR-GFP to allow in vivo detection without alteration of strain-specific characteristics. Analysis of different strain-specific characteristics included the measurement of stimulation of IL-8 secretion and adhesion in vitro using the epithelial cell line HT-29. The kinetics of intestinal distribution in mice and colonization properties in rats following oral administration was studied in vivo. Detectability of the strain in histologic specimens was analysed using fluorescence microscopy and immunohistochemistry. The identity of fluorescent E. coli strains isolated from stool samples, Peyer's patches (PP) and mesenteric lymph nodes (MLN) was determined by REP-PCR. We were able to demonstrate that EcN and EcN-GFP do not differ in stimulation of IL-8 secretion or adhesion to HT-29 cells. In vivo, EcN-GFP colonies were readily detectable by fluorescence microscopy in luminal samples and also by immunohistochemistry in histological sections allowing analysis of the kinetics of the intestinal passage following oral administration. Translocation of fluorescent and non-fluorescent bacteria into PP and MLN was noted at 6 h post oral administration. EcN-GFP was detectable initially for 14 days in faecal samples of rats, while EcR-GFP was detectable throughout the whole experiment (45 days). Challenge with ampicillin at day 45 demonstrated continuing presence of EcN-GFP in small numbers by reappearing fluorescent colonies. The plasmid was not stable in vivo since non-fluorescent EcN colonies were detected also in faecal samples by REP-PCR. In summary, transformation of EcN to obtain EcN-GFP in our study had no detectable influence on the probiotic microorganism regarding adhesion on and induction of IL-8 secretion of HT-29 cells and allows the detection in mixed microbial environments in vivo but the stability of EcN-GFP in vivo is limited.

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

BACKGROUND

Probiotic therapy has been shown to prevent the onset of pouchitis and to improve the quality of life in ulcerative colitis patients who required ileal pouch anal anastomosis. Pouchitis has been associated with elevated levels of proinflammatory cytokines and chemokines.

METHODS

In this retrospective analysis of archived endoscopic samples from responding patients enrolled in the above-mentioned trial, we were interested in studying mucosal gene expression of the pleiotropic proinflammatory cytokines (interleukin-1beta, interleukin-6), TH1 cytokines (interferon-gamma, tumor necrosis factor-alpha, interleukin-12), regulatory cytokines (interleukin-10, transforming growth factor-beta), and the chemokine interleukin-8. In addition to assessment of cytokine gene expression, the presence of polymorphonuclear cells in the mucosal tissue was evaluated.

RESULTS

Data show that patients who were treated with probiotics had significant lower mucosal mRNA expression levels of interleukin-1beta, interleukin-8, and interferon-gamma compared with placebo-treated patients. In addition, a lower number of polymorphonuclear cells was present in the tissue of patients within the probiotic group compared with the number of polymorphonuclear cells in the tissue of patients receiving placebo and patients having an episode of pouchitis.

CONCLUSIONS

These data suggest that probiotic treatment regulates the mucosal immune response by reducing mucosal levels of neutrophil-chemoattractant IL-8 and tissue influx of polymorphonuclear cells, and may further act by inhibition of T-cell activation, by reinforcement of barrier function and by a tight control of the potent pro-inflammatory cytokine IL-1beta.

Potential role of interleukin-10-secreting regulatory T cells in allergy and asthma

Allergic diseases are caused by aberrant T-helper-2 immune responses in susceptible individuals. Both naturally occurring CD4(+)CD25(+) regulatory T cells and inducible populations of antigen-specific interleukin-10-secreting regulatory T cells inhibit these inappropriate immune responses in experimental models. This article discusses the evidence that regulatory T-cell function might be impaired in allergic and asthmatic disease and that certain therapeutic regimens might function, at least in part, to promote regulatory T-cell generation. Current research strategies seek to exploit these observations to improve the generation of allergen-specific regulatory T-cell populations with the potential to provide the safe and long-term alleviation of disease symptoms.

Monostrain, multistrain and multispecies probiotics--A comparison of functionality and efficacy

This literature review was carried out to make a comparison of functionality and efficacy between monostrain, multistrain and multispecies probiotics. A monostrain probiotic is defined as containing one strain of a certain species and consequently multistrain probiotics contain more than one strain of the same species or, at least of the same genus. Arbitrarily, the term multispecies probiotics is used for preparations containing strains that belong to one or preferentially more genera. Multispecies probiotics were superior in treating antibiotic-associated diarrhea in children. Growth performance and particularly mortality in broilers could be improved with multistrain probiotics. Mice were better protected against S. Typhimurium infection with a multistrain probiotic. A multispecies probiotic provided the best clearance of E. coli O157:H7 from lambs. Rats challenged with S. Enteritidis showed best post-challenge weight gains when treated with a multispecies probiotic. Possible mechanisms underlying the enhanced effects of probiotic mixtures are discussed. It is also emphasized that strains used in multistrain and multispecies probiotics should be compatible or, preferably, synergistic. The design and use of multistrain and multispecies probiotics should be encouraged.

Probiotics inhibit nuclear factor-kappaB and induce heat shock proteins in colonic epithelial cells through proteasome inhibition

BACKGROUND AND AIMS

The extent and severity of mucosal injury in inflammatory bowel diseases are determined by the disequilibrium between 2 opposing processes: reparative and cytoprotective mechanisms vs. inflammation-induced injury. Probiotics may provide clinical benefit by ameliorating colitis; however, their mechanisms of action remain largely unknown. Our objective was to investigate microbial-epithelial interactions that could explain the beneficial therapeutic effects of probiotics.

METHODS

The effect of VSL#3-conditioned media on the nuclear factor-kappaB pathway in young adult mouse colonic epithelial cells was assessed by using monocyte chemoattractant protein-1 enzyme-linked immunosorbent assays; IkappaBalpha, IkappaBbeta, and p105 immunoblot analysis; and nuclear factor-kappaB luciferase reporter gene and proteasome assays. Effects on heat shock proteins were determined by electrophoretic mobility shift assay and immunoblot for heat shock proteins 25 and 72 in young adult mouse colonic cells. Cytoprotection against oxidant injury was determined by chromium 51 release and filamentous and globular actin assays.

RESULTS

VSL#3 produces soluble factors that inhibit the chymotrypsin-like activity of the proteasome in gut epithelial cells. Proteasome inhibition is an early event that begins almost immediately after exposure of the epithelial cells to the probiotic-conditioned media. In addition, these bacteria inhibit the proinflammatory nuclear factor-kappaB pathway through a mechanism different from the type III secretory mechanisms described for other nonpathogenic enteric flora. They also induce the expression of cytoprotective heat shock proteins in intestinal epithelial cells.

CONCLUSIONS

The resulting inhibition of nuclear factor-kappaB and increased expression of heat shock proteins may account for the anti-inflammatory and cytoprotective effects reported for probiotics and may be a novel mechanism of microbial-epithelial interaction. These effects seem to be mediated through the common unifying mechanism of proteasome inhibition.

Preventive effects of Escherichia coli strain Nissle 1917 on acute and chronic intestinal inflammation in two different murine models of colitis

Escherichia coli strain Nissle 1917 (EcN) is as effective in maintaining remission in ulcerative colitis as is treatment with mesalazine. This study aims to evaluate murine models of acute and chronic intestinal inflammation to study the antiinflammatory effect of EcN in vivo. Acute colitis was induced in mice with 2% dextran-sodium sulfate (DSS) in drinking water. EcN was administered from day -2 to day +7. Chronic colitis was induced by transfer of CD4(+) CD62L(+) T lymphocytes from BALB/c mice in SCID mice. EcN was administered three times/week from week 1 to week 8 after cell transfer. Mesenteric lymph node (MLN) cytokine secretion (of gamma interferon [IFN-gamma], interleukin 5 [IL-5], IL-6, and IL-10) was measured by enzyme-linked immunosorbent assay. Histologic sections of the colon were analyzed by using a score system ranging from 0 to 4. Intestinal contents and homogenized MLN were cultured, and the number of E. coli-like colonies was determined. EcN was identified by repetitive extragenic palindromic (REP) PCR. EcN administration to DSS-treated mice reduced the secretion of proinflammatory cytokines (IFN-gamma, 32,477 +/- 6,377 versus 9,734 +/- 1,717 [P = 0.004]; IL-6, 231 +/- 35 versus 121 +/- 17 [P = 0.02]) but had no effect on the mucosal inflammation. In the chronic experimental colitis of the transfer model, EcN ameliorated the intestinal inflammation (histology score, 2.7 +/- 0.2 versus 1.9 +/- 0.3 [P = 0.02]) and reduced the secretion of proinflammatory cytokines. Translocation of EcN and resident E. coli into MLN was observed in the chronic colitis model but not in healthy controls. Administration of EcN ameliorated acute and chronic experimental colitis by modifying proinflammatory cytokine secretion but had no influence on the acute DSS-induced colitis. In this model, preexisting colitis was necessary for translocation of EcN and resident E. coli into MLN.

Therapy of ulcerative colitis

PURPOSE OF REVIEW

The past year has brought forth several controversies regarding the treatment of ulcerative colitis along with several potentially important clinical advances. The aim of this review is to provide the practicing gastroenterologist with a summation of these recent developments, with particular emphasis on advances that have already moved toward acceptance into clinical practice.

RECENT FINDINGS

Controversies remain regarding the optimal formulations and doses of aminosalicylates. At the same time, the potential for chemoprotective effects in patients using maintenance therapy with mesalamine derivatives has been expanded. In addition, advances in biologic therapy for Crohn disease are beginning to be formally evaluated in ulcerative colitis, although the benefits of anti-tumor necrosis factor therapy in this condition remain to be established. Biologic therapies are beginning to be explored as adjunctive therapy for steroid-refractory ulcerative colitis, where trials of calcineurin inhibitors are also advancing clinical practice for this poor prognostic subgroup of patients. Finally, after surgery for ulcerative colitis, the treatment and prevention of pouchitis has become the one established indication for probiotic therapy.

SUMMARY

Despite some inroads into the medical therapy of ulcerative colitis, controversies remain regarding the optimal dosing and delivery systems of the most fundamental therapies, and how to optimize therapy for severe ulcerative colitis. Clinical research will continue to investigate new biologic agents that inhibit tumor necrosis factor and other pro-inflammatory cytokines, and ongoing trials with leukocyte apheresis are currently under way.

Bacterial probiotic modulation of dendritic cells

Intestinal dendritic cells are continually exposed to ingested microorganisms and high concentrations of endogenous bacterial flora. These cells can be activated by infectious agents and other stimuli to induce T-cell responses and to produce chemokines which recruit other cells to the local environment. Bacterial probiotics are of increasing use against intestinal disorders such as inflammatory bowel disease. They act as nonpathogenic stimuli within the gut to regain immunologic quiescence. This study was designed to determine the ability of a bacterial probiotic cocktail VSL#3 to alter cell surface antigen expression and cytokine production in bone marrow-derived dendritic cell-enriched populations. Cell surface phenotype was monitored by monoclonal fluorescent antibody staining, and cytokine levels were quantitated by enzyme-linked immunosorbent assay. High-dose probiotic upregulated the expression of C80, CD86, CD40, and major histocompatibility complex class II I-Ad. Neither B7-DC or B7RP-1 was augmented after low-dose probiotic or Lactobacillus casei treatment, but B7RP-1 showed increased expression on dendritic cells stimulated with the gram-negative bacterium Escherichia coli. Functional studies showed that probiotic did not enhance the ability of dendritic cells to induce allogeneic T-cell proliferation, as was observed for E. coli. Substantial enhancement of interleukin-10 release was observed in dendritic cell-enriched culture supernatants after 3 days of probiotic stimulation. These results demonstrate that probiotics possess the ability to modulate dendritic cell surface phenotype and cytokine release in granulocyte-macrophage colony-stimulating factor-stimulated bone marrow-derived dendritic cells. Regulation of dendritic cell cytokines by probiotics may contribute to the benefit of these molecules in treatment of intestinal diseases.

Therapeutic manipulation of the enteric microflora in inflammatory bowel diseases: antibiotics, probiotics, and prebiotics

Crohn's disease, ulcerative colitis, and pouchitis are caused by overly aggressive immune responses to a subset of commensal (nonpathogenic) enteric bacteria in genetically predisposed individuals. Clinical and experimental studies suggest that the relative balance of aggressive and protective bacterial species is altered in these disorders. Antibiotics can selectively decrease tissue invasion and eliminate aggressive bacterial species or globally decrease luminal and mucosal bacterial concentrations, depending on their spectrum of activity. Alternatively, administration of beneficial bacterial species (probiotics), poorly absorbed dietary oligosaccharides (prebiotics), or combined probiotics and prebiotics (synbiotics) can restore a predominance of beneficial Lactobacillus and Bifidobacterium species. Current clinical trials do not fulfill evidence-based criteria for using these agents in inflammatory bowel diseases (IBD), but multiple nonrigorous studies and widespread clinical experience suggest that metronidazole and/or ciprofloxacin can treat Crohn's colitis and ileocolitis (but not isolated ileal disease), perianal fistulae and pouchitis, whereas selected probiotic preparations prevent relapse of quiescent ulcerative colitis and relapsing pouchitis. These physiologic approaches offer considerable promise for treating IBD, but must be supported by rigorous controlled therapeutic trials that consider clinical disease before their widespread clinical acceptance. These agents likely will become an integral component of treating IBD in combination with traditional anti-inflammatory and immunosuppressive agents.

Lactobacillus GG in inducing and maintaining remission of Crohn's disease

Background

Experimental studies have shown that luminal antigens are involved in chronic intestinal inflammatory disorders such as Crohn's disease and ulcerative colitis. Alteration of the intestinal microflora by antibiotic or probiotic therapy may induce and maintain remission. The aim of this randomized, placebo-controlled trial was to determine the effect of oral Lactobacillus GG (L. GG) to induce or maintain medically induced remission.

Methods

Eleven patients with moderate to active Crohn's disease were enrolled in this trial to receive either L. GG (2 × 10⁹ CFU/day) or placebo for six months. All patients were started on a tapering steroid regime and received antibiotics for the week before the probiotic/placebo medication was initiated. The primary end point was sustained remission, defined as freedom from relapse at the 6 months follow-up visit. Relapse was defined as an increase in CDAI of >100 points.

Results

5/11 patients finished the study, with 2 patients in each group in sustained remission. The median time to relapse was 16 ± 4 weeks in the L. GG group and 12 ± 4.3 weeks in the placebo group (p = 0.5).

Conclusion

In this study we could not demonstrate a benefit of L. GG in inducing or maintaining medically induced remission in CD.

Probiotic effects on experimental graft-versus-host disease: let them eat yogurt

Acute graft-versus-host disease (aGVHD) often limits feasibility and outcome of allogeneic bone marrow transplantation. Current pathophysiologic concepts of aGVHD involve conditioning regimens, donor-derived T cells, proinflammatory cytokines, and bacterial lipopolysaccharide (LPS) as a major trigger for aGVHD. LPS derives mostly from gram-negative bacteria and can enter circulation through the impaired mucosal barrier after the conditioning regimen. Probiotic microorganisms have been shown to alter the composition of the intestinal microflora and thereby mediate anti-inflammatory effects. We hypothesized that modifying the enteric flora using the probiotic microorganism Lactobacillus rhamnosus GG, would ameliorate aGVHD. Here we show that oral administration of Lactobacillus rhamnosus GG before and after transplantation results in improved survival and reduced aGVHD. Furthermore, subculturing of mesenteric lymph node tissue revealed a reduced translocation of enteric bacteria. Our findings suggest that alteration of the intestinal microflora plays an important role in the initiation of experimental aGVHD.

Lactobacillus plantarum 299: beneficial in vitro immunomodulation in cells extracted from inflamed human colon

BACKGROUND AND AIM

The present study determined the pattern of cytokine secretion (interleukin [IL]-1beta, tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma and IL-10) and their cellular sources in mononuclear cells isolated from colonic mucosa from normal and ulcerative colitis (UC) in response to probiotic and pathogenic bacteria.

METHODS

Mononuclear cells were extracted from normal and active UC colonic mucosa and incubated with pure sonicates of probiotic, commensal, and pathogenic bacteria. Cytokine secretion was measured in culture supernatant and intracellular cytokine staining measured using fluorescent-activated cytometry.

RESULTS

In mononuclear cells isolated from normal mucosa, significant increases in mean IL-1beta were observed with enteropathogenic Escherichia coli (286.3 +/- 138.7 pg/mL P < 0.05) and E. coli (440.5 +/- 194.0 pg/mL P < 0.01) compared with unstimulated control cells (16.7 +/- 4.8 pg/mL). In contrast, mononuclear cells isolated from active UC mucosa produced significant increases in mean IL-1beta in response to stimulation with Salmonella dublin (230.5 +/- 38.8 pg/mL P < 0.05), enteropathogenic E. coli (231.7 +/- 45.3 pg/mL P < 0.05) and E. coli (465.4 +/- 60.2 pg/mL P < 0.001) compared with unstimulated control cells (60.7 +/- 17.1 pg/mL). Escherichia coli also produced significant mean increases of TNF-alpha and IFN-gamma compared with unstimulated control cells. No significant increases in IL-1beta, TNF-alpha or IFN-gamma were observed with Lactobacillus plantarum in cells derived from normal or inflamed mucosa. Strikingly, incubation of L. plantarum with mononuclear cells isolated from active UC mucosa resulted in significant increases of mean IL-10 (327 +/- 53.5 pg/mL, P < 0.05) compared with unstimulated control cells (29.7 +/- 13.2 pg/mL). Intracellular cytokine staining confirmed T-cell and macrophage IL-10 production after L. plantarum stimulation.

CONCLUSIONS

Lactobacillus plantarum demonstrates beneficial immunomodulatory activity by increasing IL-10 synthesis and secretion in macrophages and T-cells derived from the inflamed colon. This may provide a mechanism through which probiotic bacteria ameliorate inappropriate inflammation and induce tolerance.

The potential for probiotics to prevent bacterial vaginosis and preterm labor

Infections of the urogenital tract in women represent a major burden on the quality of life of women and on the health care system of Canada and other countries. Complications arising from bacterial vaginosis (BV) include increased risk of sexually transmitted diseases including human immunodeficiency virus and elevated risk of preterm birth (PTB). Pharmaceutical interventions, such as antibiotics, have been suboptimally effective and have failed to reduce the incidence of PTB. The absence of lactobacilli in the vagina, a specific feature of BV, raises the question as to whether restoration of lactobacilli, by probiotic therapy, can restore the normal flora and improve the chances of having a healthy term pregnancy. The rationale for probiotic use in pregnant women is quite strong. Certain lactobacilli strains can safely colonize the vagina after oral and vaginal administration, displace and kill pathogens including Gardnerella vaginalis and Escherichia coli, and modulate the immune response to interfere with the inflammatory cascade that leads to PTB. Additional attributes of probiotics include their potential to degrade lipids and enhance cytokine levels, which promote embryo development. In a society that focuses on disease rather than health and drug therapy rather than natural preventive measures, it will take some effort to get remedies such as probiotics into mainstream care. Perhaps the escalating health care budgets and emergence of "superbugs" will provide the incentives to put in place clinical trials designed to evaluate how best to use the commensal organisms that, after all, make up more of our body than human cells, and without which none of us would survive.