Ineffectiveness of Lactobacillus johnsonii LA1 for prophylaxis of postoperative recurrence in Crohn's disease: a randomised, double blind, placebo controlled GETAID trial

[Postoperative recurrence of Crohn's disease, and its prevention]

Crohn's disease is a chronic, progressive disabling condition ultimately leading to stricturing and/or penetrating complications. The need for surgery may be as high as 70% in patients with severe active disease or complications. However, relapse may develop in a significant proportion of the patients after surgery leading to frequent re-operations. Despite emerging data, postoperative prevention is still controversial. After careful evaluation of the individual risk a tailored therapy should be considered. In patients with small risk for relapse mesalazine or in selected cases no-treatment may be an option. In patients with a moderate-to-high risk azathioprine should be considered together with metronidazole in the three months. Follow-up ileocolonoscopy 6-12 months after the surgery is helpful in the determination of endoscopic severity and may assist in the optimization of the therapy. In most severe cases anti-TNF agents may be appropriate for postoperative prevention and therapy.

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.

Meta-analysis: targeting the intestinal microbiota in prophylaxis for post-operative Crohn's disease

BACKGROUND

Enteric bacteria play an important early role in the pathogenesis of Crohn's disease.

AIM

To perform a meta-analysis of trials testing antibiotics or probiotics for prevention of post-operative recurrence of Crohn's disease.

METHODS

Review of all randomized controlled trials comparing antibiotics or probiotics with placebo in prevention of endoscopic or clinical recurrence of Crohn's disease after surgical resection. Fixed-effect meta-analysis was performed with dichotomous data summarized using relative risk with 95% confidence intervals, where appropriate.

RESULTS

Seven studies were identified as suitable for inclusion (two comparing antibiotics with placebo, five comparing probiotics with placebo). The use of nitroimidazole antibiotics (metronidazole, ornidazole) reduced the risk of clinical (RR 0.23; 95% CI 0.09-0.57, NNT = 4) and endoscopic (RR 0.44; 95% CI 0.26-0.74, NNT = 4) recurrence relative to placebo. However, these agents were associated with higher risk of adverse events (RR 2.39, 95% CI 1.5-3.7) and patient withdrawal. Probiotic administration was not associated with any significant difference in risk of recurrence compared with placebo.

CONCLUSIONS

Nitroimidazole antibiotics are effective in the prevention of post-operative Crohn's disease recurrence, but their side-effects limit acceptability. Probiotics have failed to show efficacy for post-operative prophylaxis, but may merit further study.

Guidance for substantiating the evidence for beneficial effects of probiotics: probiotics in chronic inflammatory bowel disease and the functional disorder irritable bowel syndrome

Ulcerative colitis and Crohn's disease, the 2 distinct idiopathic pathologies of inflammatory bowel diseases, are spontaneously relapsing, immunologically mediated disorders of the gastrointestinal tract. Selected probiotics strains have been proven to be clinically effective in maintaining remission in patients with ulcerative colitis. None of the probiotics thus far tested has been shown to be effective in induction of remission or in maintenance of remission in patients with Crohn's disease. The multispecies probiotics mixture of 8 strains seems effective in the maintenance of remission in pouchitis. Irritable bowel syndrome is a functional bowel disorder manifested by chronic, recurring abdominal pain or discomfort associated with disturbed bowel habit in the absence of structural abnormalities likely to account for these symptoms. Recently conducted appropriately powered studies with different (combinations of) probiotics show positive results on reduction of symptoms, although a considerable placebo effect is also found. Mechanistic studies aimed at pathophysiological mechanisms of inflammatory bowel diseases can identify new targets for probiotic bacteria.

Meta-analysis: the effect and adverse events of Lactobacilli versus placebo in maintenance therapy for Crohn disease

BACKGROUND

Lactobacilli are used in an attempt to maintain remission for Crohn disease. The aim of this study was to evaluate the efficacy and adverse events of Lactobacilli compared with placebo in maintenance therapy for Crohn disease.

METHODS

We searched MEDLINE, EMBASE, the Cochrane Controlled Trials Register, OVID and BIOSIS. All randomized trials comparing Lactobacilli with placebo in maintenance therapy for Crohn disease were included.

RESULTS

Six randomized controlled trials with a total of 359 participants met the inclusion criteria. From the meta-analyses, the relative risk (RR) of clinical relapse rate was 1.15 (95% confidence interval (CI) 0.90-1.48) comparing Lactobacilli with placebo and RR of endoscopic relapse rate was 1.31 (95%CI 0.57-3.00). Subgroup analyses showed RR for clinical relapse rates of Lactobacilli versus placebo was 0.99 (95%CI 0.76-1.29) in adults, 1.85 (95%CI 1.00-3.41) in children, 1.68 (95%CI 1.07-2.64) in Lactobacillus rhamnosus strain GG and 0.91 (95%CI 0.68-1.23) in Lactobacillus johnsonii respectively. The pooled RR of adverse events was 0.83 (95%CI 0.61-1.12).

CONCLUSION

Our meta-analysis suggests that compared with placebo, administration of L. rhamnosus strain GG as maintenance therapy may increase the relapse rates of Crohn disease. L. johnsonii is inefficacious in reducing the incidence of relapse.

Current level of consensus on probiotic science--report of an expert meeting--London, 23 November 2009

The present paper summarizes the consensus views of a group of 9 European clinicians and scientists on the current state of scientific knowledge on probiotics, covering those areas where there is substantial evidence for beneficial effects and those where the evidence base is poor or inconsistent. There was general agreement that probiotic effects were species and often strain specific. The experts agreed that some probiotics were effective in reducing the incidence and duration of rotavirus diarrhoea in infants, antibiotic-associated diarrhoea in adults and, for certain probiotics, Clostridium difficile infections. Some probiotics are associated with symptomatic improvements in irritable bowel syndrome and alleviation of digestive discomfort. Probiotics can reduce the frequency and severity of necrotizing enterocolitis in premature infants and have been shown to regulate intestinal immunity. Several other clinical effects of probiotics, including their role in inflammatory bowel disease, atopic dermatitis, respiratory or genito-urinary infections or H.pylori adjuvant treatment were thought promising but inconsistent.

Interventions for prevention of post-operative recurrence of Crohn's disease

BACKGROUND

Recurrence of Crohn's disease is common after intestinal resection. A number of agents have been studied in controlled trials with the goal of reducing the risk of endoscopic or clinical recurrence of Crohn's disease following surgery.

OBJECTIVES

To undertake a systematic review of the use of medical therapies for the prevention of post-operative recurrence of Crohn's disease

SEARCH STRATEGY

MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify relevant studies. References from selected papers and abstracts from Digestive Disease Week were also searched.

SELECTION CRITERIA

Randomised controlled trials that compared medical therapy to placebo or other medical agents for the prevention of recurrence of intestinal Crohn's disease were selected for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors reviewed all abstracts containing search terms, and those meeting inclusion criteria were selected for full data abstraction. Dichotomous data were summarised using relative risk and 95% confidence intervals. A fixed-effects model was used, and sensitivity analysis performed.

MAIN RESULTS

Twenty-three studies were identified for inclusion. Probiotics were not superior to placebo for any outcome measured. The use of nitroimidazole antibiotics appeared to reduce the risk of clinical (RR 0.23; 95%CI 0.09 to 0.57, NNT=4) and endoscopic (RR 0.44; 95%CI 0.26 to 0.74, NNT = 4) recurrence relative to placebo. However, these agents were associated with higher risk of serious adverse events (RR 2.39, 95% CI 1.5 to 3.7). Mesalamine therapy was associated with a significantly reduced risk of clinical recurrence (RR 0.76; 95% CI 0.62 to 0.94, NNT = 12), and severe endoscopic recurrence (RR 0.50; 95% CI 0.29 to 0.84, NNT = 8) when compared to placebo. Azathioprine/6MP was also associated with a significantly reduced risk of clinical recurrence (RR 0.59; 95% CI 0.38 to 0.92, NNT = 7), and severe endoscopic recurrence (RR 0.64; 95% CI 0.44 to 0.92, NNT = 4), when compared to placebo. Neither agent had a higher risk than placebo of serious adverse events. When compared to azathioprine/6MP, mesalamine was associated with a higher risk of any endoscopic recurrence (RR 1.45, 95% CI 1.03 to 2.06), but a lower risk of serious adverse events (RR 0.51; 95% CI 0.30 to 0.89). There was no significant difference between mesalamine and azathioprine/6MP for any other outcome.

AUTHORS' CONCLUSIONS

There are insufficient randomised controlled trials of infliximab, budesonide, tenovil and interleukin-10 to draw conclusions. Nitro-imidazole antibiotics, mesalamine and immunosuppressive therapy with azathioprine/6-MP or infliximab all appear to be superior to placebo for the prevention of post-operative recurrence of Crohn's disease. The cost, toxicity and tolerability of these approaches require careful consideration to determine the optimal approach for post-operative prophylaxis.

Inflammatory bowel disease, gut bacteria and probiotic therapy

Crohn's disease (CD) and ulcerative colitis (UC) are the two major forms of inflammatory bowel disease (IBD) and both diseases lead to high morbidity and health care costs. Complex interactions between the immune system, enteric commensal bacteria and host genotype are thought to underlie the development of IBD although the precise aetiology of this group of diseases is still unknown. The understanding of the composition and complexity of the normal gut microbiota has been greatly aided by the use of molecular methods and is likely to be further increased with the advent of metagenomics and metatranscriptomics approaches, which will allow an increasingly more holistic assessment of the microbiome with respect to both diversity and function of the commensal gut microbiota. Studies thus far have shown that the intestinal microbiota drives the development of the gut immune system and can induce immune homeostasis as well as contribute to the development of IBD. Probiotics which deliver some of the beneficial immunomodulatory effects of the commensal gut microbiota and induce immune homeostasis have been proposed as a suitable treatment for mild to moderate IBD. This review provides an overview over the current understanding of the commensal gut microbiota, its interactions with the mucosal immune system and its capacity to induce both gut homeostasis as well as dysregulation of the immune system. Bacterial-host events, including interactions with pattern recognition receptors (PRRs) expressed on epithelial cells and dendritic cells (DCs) and the resultant impact on immune responses at mucosal surfaces will be discussed.

Preferential promotion of apoptosis of monocytes by Lactobacillus casei rhamnosus soluble factors

BACKGROUND & AIMS

Inflammatory bowel disease (IBD) is characterized by dense infiltrates of and defective apoptosis by mucosal cell populations. Some probiotics inhibit monocytes' expansion, although mechanisms remain unknown. Supernatants of Lactobacillus strains were investigated for inducing apoptosis of monocytes.

METHODS

Secreted factors produced by Lactobacillus strains were tested on human lymphocytes, monocytes and a human monocytic leukemia-cell line (THP-1). Cell death mechanisms were investigated by a variety of methods. Lipopolysaccharide (LPS)-induced proinflammatory cytokines (IL-1beta, IL-6, IL-8, TNF-alpha) and anti-inflammatory TGF-beta1 were determined.

RESULTS

Soluble factor(s) from Lactobacillus casei rhamnosus strain supernatants (LcrS) effectively induced apoptosis of immune cells. These were mainly soluble proteins (MW 5-30 kDa; LcrS(5-30)). For immune cells, but not human colonic epithelial carcinoma cells (HT-29), pretreatment with LcrS(5-30) significantly promoted apoptosis via a mitochondrial pathway. LcrS(5-30) suppressed pro-inflammatory cytokines and induced anti-inflammatory TGF-beta1.

CONCLUSIONS

Probiotic Lcr produced heat-stable molecules (MW range 5-30 kDa) that promoted immune cell apoptosis without affecting intestinal epithelial cells. LcrS(5-30) triggered apoptosis by a mitochondrial pathway, but not via TGF-beta signaling pathway. LcrS(5-30) also inhibited LPS-induced inflammatory cytokines by immune cells. Thus, LcrS(5-30) promotes apoptosis of immune cells, and suggests probiotics-based regimens for prevention of IBD.

Azathioprine and 6-mercaptopurine for the prevention of postoperative recurrence in Crohn's disease: a meta-analysis

OBJECTIVES

To evaluate the efficacy and safety of purine analogs (azathioprine, 6-mercaptopurine (6-MP)) in the prevention of postoperative recurrence in Crohn's disease (CD).

METHODS

We searched MEDLINE, the Cochrane Library, and EMBASE. The primary end points, clinical and endoscopic recurrence at 1 and 2 years, and safety were analyzed by the methods of Peto and Der Simonian and Laird.

RESULTS

Four controlled trials enrolled 433 patients and compared azathioprine (n=3) or (6-MP) (n=1) with control arms (placebo with or without antibiotic induction therapy or mesalamine). In the overall analysis, purine analogs were more effective than control arms in preventing clinical recurrence at 1 year (mean difference, 95% confidence interval (CI): 8, 1-15%, P=0.021, number needed to treat (NNT)=13) and 2 years (mean difference, 95% CI: 13%, 2-24%, P=0.018, NNT=8). In sensitivity analyses, the efficacy of purine analogs was superior to that of placebo for the prevention of clinical and endoscopic recurrence at 1 year (mean differences, 95% CI: 13, 1.8-25%, P=0.025, NNT=7, and 23%, 9-37%, P=0.0016, NNT=4, respectively). At 1 year, in the overall analysis, purine analogs were more effective than control arms were in preventing severe (i2-4) endoscopic recurrence (mean difference, CI 95%: 15, 1.8-29%, P=0.026, NNT=7), but they were not effective in the prevention of very severe (i3-4) recurrence. The rate of adverse events leading to drug withdrawal was higher in thiopurine-treated patients than in control arms (17.2 vs. 9.8%, respectively, P=0.021).

CONCLUSIONS

Purine analogs are more effective than placebo in preventing both clinical and endoscopic postoperative recurrence in CD, but they are associated with a higher rate of adverse events leading to drug withdrawal.

Association between entero-hepatic Helicobacter species and Crohn's disease: a prospective cross-sectional study

BACKGROUND

The pathogenesis of Crohn's disease (CD) involved microbial factors. Some Helicobacter species, the so-called entero-hepatic Helicobacters (EHH), can naturally colonize the intestinal surface and have been detected in humans. Aim To look for an association between CD and the presence of EHH DNA in intestinal biopsies.

METHODS

Two groups of patients were included prospectively in a multicentre cross-sectional study: CD patients with an endoscopic post-operative recurrence within 2 years following a surgical resection and controls screened for colorectal polyps or cancer. Intestinal biopsies were taken for Helicobacter culture and Helicobacter 16S DNA detection. If positive, the EHH species were identified with specific PCRs, sequencing and denaturing gradient gel electrophoresis.

RESULTS

In the 165 included patients (73 CD and 92 controls), Helicobacter cultures were negative. PCR was positive in 44% of CD and 47% of controls. After age-adjustment, CD was significantly associated with EHH in intestinal biopsies (OR = 2.58; 95%CI: 1.04-6.67). All EHH species detected were identified as Helicobacter pullorum and the closely related species Helicobacter canadensis.

CONCLUSION

Crohn's disease is associated with the presence of EHH species DNA in intestinal biopsies after adjustment for age. Whether these species play a role in the pathophysiology of CD remains to be determined.

Prevention and Treatment Options for Postoperative Crohn's Disease: A Clinical Dilemma

The majority of patients with Crohn's disease require surgery for disease-related complications. Postoperative Crohn's disease recurrence is common after intestinal resection. The optimal management strategy for postoperative recurrence of Crohn's disease is controversial. In the absence of universally adopted guidelines, clinicians and patients must discuss and weigh the risks and benefits of postoperative pharmacotherapy. Those patients at low risk of disease recurrence may not require treatment. On the other hand, patients with more aggressive disease and high risk of recurrence may be best treated early in the postoperative period with an immunomodulator or antitumor necrosis factor agents. Ideally, postoperative treatment decisions would be made using predictable, reliable, and reproducible clinical prediction criteria that would guide treatment. This article reviews the data on postoperative Crohn's disease, including predictors of early recurrence, available options for postoperative monitoring, timing of initiation, and choice of postoperative therapy for prevention and management.

A new animal model of postsurgical bowel inflammation and fibrosis: the effect of commensal microflora

OBJECTIVE

Ileocaecal resection (ICR) is common in Crohn's disease. Inflammation and fibrosis frequently recur at the site of anastomosis or in the small intestine (SI). No animal models of postsurgical inflammation and fibrosis exist. A model of ICR was developed in interleukin 10 (IL10) null and wild-type (WT) mice to test the hypothesis that ICR promotes postsurgical inflammation and fibrosis in the SI or anastomosis of genetically susceptible IL10 null, but not WT or germ-free (GF)-IL10 null mice.

METHODS

GF-IL10 null mice were conventionalised (CONV) and 3 weeks later randomised to ICR, transection (T) or no treatment (NoTx). Age-matched conventionally raised (CONV) WT and GF-IL10 null mice received ICR, T or NoTx. Animals were killed 28 days later. Histological scoring, real-time PCR for tumour necrosis factor alpha and collagen, and immunostaining for CD3(+) T cells assessed inflammation and fibrosis.

RESULTS

After ICR, CONV-IL10 null, but not CONV-WT mice, developed significant inflammation and fibrosis in the SI and inflammation in anastomosis compared with NoTx or T controls. Fibrosis occurred in the anastomosis of both CONV-IL10 null and CONV-WT mice following ICR. GF-IL10 null mice developed little or no inflammation or fibrosis in the SI or anastomosis after ICR.

CONCLUSIONS

ICR in CONV-IL10 null mice provides a new animal model of postsurgical inflammation and fibrosis in the SI and anastomosis. Absence of inflammation and fibrosis in the SI of CONV-WT and GF-IL10 null mice following ICR indicates that postsurgical small bowel disease occurs only in genetically susceptible IL10 null mice and is bacteria dependent.

Altering and assessing persistence of genetically modified E. coli MG1655 in the large bowel

One of the primary factors limiting the efficacy of probiotic therapies is short persistence time. Utilizing a novel method for assessment of persistence in the large bowel independent of survival of the organisms in the upper GI tract, we tested whether overexpression of the type 1 pilus, a colonization factor, or the presence of secretory immunoglobulin A (sIgA) might increase the persistence time of a laboratory strain of E. coli in the gut. For this purpose, cecal ostomies were created in mice and bacteria were placed in the ostomies, with or without sIgA. The persistence of the bacteria was assessed by evaluating the length of time after placement in which the bacteria were found in fecal samples. E. coli MG1655 expressing pili with the mannose-specific adhesin persisted in vivo significantly longer [mean (hours) +/- SEM: 91.50 +/- 15.98, n = 12] than bacteria expressing pili without adhesin [43.67 +/- 8.22, n = 12] (P = 0.01) and significantly longer than bacteria expressing neither pili nor adhesin [22.00 +/- 4.22, n = 12] (P = 0.0004). Although the persistence time of bacteria was not significantly affected by the presence of sIgA, the sIgA did cause a relative increase in retention of inert particles. These results, combined with an acute increase in stool production and stool water content in those animals not receiving sIgA following introduction of bacteria, suggest that sIgA might have anti-inflammatory properties in the gut when administered with enteric bacteria. Modifying expression of probiotic colonization factors may provide substantial benefit to patients with digestive tract diseases by virtue of increased persistence of the probiotic and, in the case of sIgA, an anti-inflammatory effect. This novel in vivo model may be useful in evaluating persistence time in a variety of current and future probiotic regimens.

Long-term prevention of post-operative recurrence in Crohn's disease cannot be affected by mesalazine

BACKGROUND

Prevention of post-operative recurrence has a central role in the management of Crohn's Disease (CD). Many drugs have been evaluated in prospective randomised controlled trials (RCTs) but the results are disappointing. Mesalazine, the drug more extensively investigated, has been shown to be effective for preventing recurrence in the short-term; however, the overall benefit is small and no data are available on the long-term effectiveness.

AIM

To compare the long-term occurrence of post-operative recurrence in patients who received regular prophylactic treatment with mesalazine with patients who did not receive prophylaxis after the first radical resection for ileo-caecal CD.

PATIENTS AND METHODS

The records of 216 patients with ileo-caecal CD at their first resection were reviewed: 146 patients (67.6%) received post-operative prophylaxis with mesalazine while 70 patients (32.4%) received no prophylaxis. Allocation of patients in the two groups was determined by patients' preferences and by different policies in the post-operative prophylactic approach. The mean follow-up after surgery was 153.7 months (range 12-544). The co-primary endpoints were post-operative clinical and surgical recurrence.

STATISTICAL ANALYSIS

Kaplan-Meier survival method, Chi-square, Student t-test.

RESULTS

The two groups were comparable with regard to gender, age at surgery, smoking habits, pattern of CD (perforating/not perforating), and disease duration before surgery. One year after surgery, a small, not statistically significant, risk reduction in clinical recurrence was observed in mesalazine treated group (-7.6%; 95% CI -18.0% to 2.8%). Within 10 years after surgery, the cumulative probability of clinical recurrence and surgical recurrence were similar in the two groups (Log Rank test p=0.9 and p=0.1 respectively).

CONCLUSION

Mesalazine prophylaxis is not effective for preventing the long-term post-operative recurrence in ileo-caecal Crohn's disease.

Probiotics in pediatric inflammatory bowel diseases

The intestinal microbiota plays a key role in the initiation and perpetuation of inflammatory bowel diseases (IBD). As such, there is a strong rationale to use agents such as probiotics to modulate the gut microbiome as a treatment strategy for these disorders. Furthermore, the potential toxicities of current IBD therapies make probiotics attractive medications for patients and physicians. However, although much attention is being placed on probiotic therapy, relatively few well-designed trials have evaluated its efficacy in the management of IBD, particularly in the pediatric population. This article examines the currently available published trials studying probiotics for the treatment of IBD, with particular emphasis on their role in pediatric IBD patients.

Postoperative Crohn's disease: prevention and treatment

Crohn's disease is a chronic, relapsing-remitting inflammatory disease of the intestinal tract that commonly requires surgical treatment. Unfortunately, the majority of patients will ultimately develop postoperative disease recurrence and require subsequent surgery. A number of medications have been researched for the maintenance of postoperative remission. Of these, few have demonstrated consistent efficacy. A recently published randomized, controlled trial indicated that infliximab is effective in the maintenance of postoperative remission.

[Probiotics in gastrointestinal disorders]

Probiotics are preparations containing viable microorganisms that confer potential health benefits for the host. Alteration of bacterial flora both in terms of specific content and concentration may be beneficial in many gastrointestinal disorders. Probiotics are widely used for the management of these conditions in many countries. However, mechanisms of probiotics are incompletely understood. Benefits observed clinically with one species or combinations of species can not be generalized. The optimal dose of treatment has to be determined. Although probiotics are generally regarded safe, caution is needed when using these supplements routinely. It has been proved, that severe adverse events can occur as a complication of probiotic treatment. This review summarizes the recent knowledge concerning the use of probiotics in gastrointestinal disorders.

Inflammatory Disease Processes and Interactions with Nutrition

Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain ω-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (ω-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.

Clinical and surgical recurrence of Crohn's disease after ileocolonic resection in a specialist unit

BACKGROUND

Postoperative clinical and endoscopic recurrence is common in Crohn's disease.

AIM

We aimed to assess postoperative recurrence and management in a cross-sectional patient cohort in one specialist unit, before the introduction of a uniform postoperative preventive strategy.

METHODS

Review of patients who had an ileocolonic resection for Crohn's disease between 2002 and 2005 in a secondary and tertiary care specialist centre.

RESULTS

Ninety-nine patients (42 male; 57 female; mean age, 37 years) with a median disease duration of 10 years, were reviewed. Indications for surgery were obstruction (n=61), failed medical therapy (n=31) and internal fistula(e) (n=7). Thirty patients (30%) were active smokers at the time of resection. Fifty patients (51%) had at least one previous Crohn's resection. Clinical and surgical recurrence rates were 28 and 5%, respectively, at 1 year. All five patients had the same indication for their further surgery as for their index operation (four fistulizing or stricturing). Median time to clinical recurrence was 10 months in those with recurrence. Nineteen percent of patients had an ileocolonoscopy at a median of 6 months after surgery, and 60% had been reviewed by a gastroenterologist, after surgery. Clinical recurrence occurred in nine of 28 (32%) without and 19 of 71 with (26%) postoperative medical therapy (P=NS).

CONCLUSION

Postoperative recurrence of Crohn's disease was high in the short term. The indication for repeat surgery stayed true within patients. Prospective treatment strategies, based on recent trial evidence, are needed to diminish postoperative recurrence.

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.

Postoperative therapy for Crohn's disease

Prevention of the postoperative recurrence of Crohn's disease (CD) remains a challenging clinical problem. The majority of patients with CD will need surgery for treatment of the disease, most of these patients will develop recurrent symptoms within 5 years postoperatively, and many patients will need reoperation within 10 years. In patients with an ileocolic anastomosis, endoscopic recurrence precedes clinical recurrence and the severity of endoscopic recurrence correlates with the risk of clinical recurrence. Despite multiple studies, the best postoperative prophylactic therapy remains uncertain. Numerous randomized controlled trials of 5-aminosalicylates have shown only modest effect. Antibiotics, including metronidazole and ornidazole, decrease short-term, but not long-term endoscopic recurrence and are limited by side effects. Immunomodulators have yet to be extensively evaluated, although limited data suggest possible efficacy in preventing postoperative recurrence, particularly in high-risk patients. This review will evaluate the current state of the art therapy for postoperative prophylaxis in CD, with an emphasis on critical analysis of the available randomized controlled trials.

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.

Clinical evidence for immunomodulatory effects of probiotic bacteria

Close, tightly orchestrated interactions between the intestinal epithelium and the mucosa-associated immune system are critical for normal intestinal absorptive and immunological functions. Recent data indicate that commensal intestinal microbiota represents a major modulator of intestinal homeostasis. This review analyzes the process of intestinal colonization and the interaction of microbiota with the intestinal epithelium and mucosal immune system, with special reference to the first years of extrauterine life. Dysregulation of the symbiotic interaction between intestinal microbiota and the mucosa may result in a pathological condition with potential clinical repercussions. Based on the concept that there is a beneficial and symbiotic relation between the host and endogenous microbiota, strategies aimed at directly modulating intestinal microbiota with regard to disease prevention or treatment have been developed. One strategy involves administering viable probiotic bacteria. Clinical evidence for the beneficial effect of probiotics in the prevention and/or treatment of necrotizing enterocolitis, infectious and antibiotic-associated diarrhea, allergic diseases, and inflammatory bowel disorders is reviewed herein.

Managing medical complications and recurrence after surgery for Crohn's disease

Each of the medical and surgical therapies for Crohn's disease has inherent advantages and disadvantages that must be balanced for patients with moderate to severe disease. Most patients with Crohn's disease require surgery at some point during the lifelong illness, but surgical therapy is not curative for most patients, as postoperative recurrence of Crohn's disease is common and can pose diagnostic and therapeutic challenges. Disease monitoring and appropriate prophylaxis are necessary in patients at high risk.

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.

Role of probiotic therapy in IBD

There is mounting evidence that probiotic therapy may alter disease expression in both animal models of IBD and in patients with IBD. The effects appear to be modest at best and may reflect the choice of probiotic organism, the variability in concentrations of organisms administered, and the variability of the diseases being treated. This review examines the data of all fully published articles currently available for the role of probiotics in the treatment of IBD.

Meta-analysis of the placebo rates of clinical relapse and severe endoscopic recurrence in postoperative Crohn's disease

BACKGROUNDS & AIMS

The benefit of therapy for prevention of postoperative recurrence of Crohn's disease (CD) is limited. Clinical relapse and severe endoscopic recurrence are the main outcomes in the evaluation of trials on prevention of recurrence. The aim of this meta-analysis was to focus on knowledge of the placebo rates of relapse and recurrence in postoperative CD and to identify factors influencing these rates.

METHODS

We performed a meta-analysis of placebo-controlled, randomized clinical trials, evaluating therapies for postoperative maintenance of CD identified on MEDLINE from 1990 to 2006. Primary outcomes were clinical relapse and severe endoscopic recurrence.

RESULTS

The pooled estimate of the placebo relapse rate was 23.7% (95% confidence interval [CI], 13-35; range 0-78). There was a statistically significant heterogeneity among studies (P < .0001). Heterogeneity in clinical relapse was present even if the trials were stratified according to the time of outcome. The pooled estimate of the severe endoscopic recurrence rate was 50.2% (95% CI, 28-73; range, 30-79). There was significant heterogeneity among the studies (P = .00038). This heterogeneity was less apparent in studies carried out within 12 months. The logistic analysis identified only duration of follow-up as a variable associated with different placebo relapse rates. No variable was identified as a predictor of a placebo endoscopic recurrence rate.

CONCLUSIONS

There is significant heterogeneity among placebo rates in postoperative CD. No single design variable was identified that explained the heterogeneity in placebo outcomes for clinical or endoscopic recurrence.

Is there any place for alimentary probiotics, prebiotics or synbiotics, for patients with inflammatory bowel disease?

The pathogenesis of inflammatory bowel disease (IBD) involves an interaction between genetically determined host susceptibility, dysregulated immune response, and the enteric microbiota. Ecological treatments including probiotics, prebiotics, and synbiotics are actively studied in Crohn's disease (CD), ulcerative colitis (UC) and pouchitis. We review herein the literature on the rational use of probiotics in IBD considering efficacy (as evaluated in randomized controlled trials), mechanisms of action and safety issues. A probiotic effect is strictly restricted to one defined strain and cannot be generalized from one to another. There is evidence of efficacy of some probiotic drugs in pouchitis (VSL#3), and in the prevention of recurrence of UC (Escherichia coli Nissle 1917). However, the evidence for efficacy of probiotic drugs in CD is still low as well as that of dietary ecological treatments. Despite an ecological (hopefully nutritional) treatment of IBD is promising, many questions remain unanswered and further clinical and fundamental studies are needed.

Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients

A decrease in the abundance and biodiversity of intestinal bacteria within the dominant phylum Firmicutes has been observed repeatedly in Crohn disease (CD) patients. In this study, we determined the composition of the mucosa-associated microbiota of CD patients at the time of surgical resection and 6 months later using FISH analysis. We found that a reduction of a major member of Firmicutes, Faecalibacterium prausnitzii, is associated with a higher risk of postoperative recurrence of ileal CD. A lower proportion of F. prausnitzii on resected ileal Crohn mucosa also was associated with endoscopic recurrence at 6 months. To evaluate the immunomodulatory properties of F. prausnitzii we analyzed the anti-inflammatory effects of F. prausnitzii in both in vitro (cellular models) and in vivo [2,4,6-trinitrobenzenesulphonic acid (TNBS)-induced] colitis in mice. In Caco-2 cells transfected with a reporter gene for NF-kappaB activity, F. prausnitzii had no effect on IL-1beta-induced NF-kappaB activity, whereas the supernatant abolished it. In vitro peripheral blood mononuclear cell stimulation by F. prausnitzii led to significantly lower IL-12 and IFN-gamma production levels and higher secretion of IL-10. Oral administration of either live F. prausnitzii or its supernatant markedly reduced the severity of TNBS colitis and tended to correct the dysbiosis associated with TNBS colitis, as demonstrated by real-time quantitative PCR (qPCR) analysis. F. prausnitzii exhibits anti-inflammatory effects on cellular and TNBS colitis models, partly due to secreted metabolites able to block NF-kappaB activation and IL-8 production. These results suggest that counterbalancing dysbiosis using F. prausnitzii as a probiotic is a promising strategy in CD treatment.

Probiotics, prebiotics, and synbiotics

According to the German definition, probiotics are defined viable microorganisms, sufficient amounts of which reach the intestine in an active state and thus exert positive health effects. Numerous probiotic microorganisms (e.g. Lactobacillus rhamnosus GG, L. reuteri, bifidobacteria and certain strains of L. casei or the L. acidophilus-group) are used in probiotic food, particularly fermented milk products, or have been investigated--as well as Escherichia coli strain Nissle 1917, certain enterococci (Enterococcus faecium SF68) and the probiotic yeast Saccharomyces boulardii--with regard to their medicinal use. Among the numerous purported health benefits attributed to probiotic bacteria, the (transient) modulation of the intestinal microflora of the host and the capacity to interact with the immune system directly or mediated by the autochthonous microflora, are basic mechanisms. They are supported by an increasing number of in vitro and in vivo experiments using conventional and molecular biologic methods. In addition to these, a limited number of randomized, well-controlled human intervention trials have been reported. Well-established probiotic effects are: 1. Prevention and/or reduction of duration and complaints of rotavirus-induced or antibiotic-associated diarrhea as well as alleviation of complaints due to lactose intolerance. 2. Reduction of the concentration of cancer-promoting enzymes and/or putrefactive (bacterial) metabolites in the gut. 3. Prevention and alleviation of unspecific and irregular complaints of the gastrointestinal tracts in healthy people. 4. Beneficial effects on microbial aberrancies, inflammation and other complaints in connection with: inflammatory diseases of the gastrointestinal tract, Helicobacter pylori infection or bacterial overgrowth. 5. Normalization of passing stool and stool consistency in subjects suffering from obstipation or an irritable colon. 6. Prevention or alleviation of allergies and atopic diseases in infants. 7. Prevention of respiratory tract infections (common cold, influenza) and other infectious diseases as well as treatment of urogenital infections. Insufficient or at most preliminary evidence exists with respect to cancer prevention, a so-called hypocholesterolemic effect, improvement of the mouth flora and caries prevention or prevention or therapy of ischemic heart diseases or amelioration of autoimmune diseases (e.g. arthritis). A prebiotic is "a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well being and health", whereas synergistic combinations of pro- and prebiotics are called synbiotics. Today, only bifidogenic, non-digestible oligosaccharides (particularly inulin, its hydrolysis product oligofructose, and (trans)galactooligosaccharides), fulfill all the criteria for prebiotic classification. They are dietary fibers with a well-established positive impact on the intestinal microflora. Other health effects of prebiotics (prevention of diarrhoea or obstipation, modulation of the metabolism of the intestinal flora, cancer prevention, positive effects on lipid metabolism, stimulation of mineral adsorption and immunomodulatory properties) are indirect, i.e. mediated by the intestinal microflora, and therefore less-well proven. In the last years, successful attempts have been reported to make infant formula more breast milk-like by the addition of fructo- and (primarily) galactooligosaccharides.

Eukaryotic-microbiota crosstalk: potential mechanisms for health benefits of prebiotics and probiotics

The ability to link dietary consumption of prebiotic food ingredients and probiotic microorganisms to health benefits rests, in part, on our ability to identify both the extent to which these factors alter human microbiome activity and/or structure and the ability to engage eukaryotic cells necessary to transduce signals originating from the microbiome. The human microbiome consists of bacterial, archaeal, and fungal components that reside in mucosal surfaces of the gut, the airways, and the urogenital tract. Characterization of the symbiotic nature of the relationship between eukaryotic cells and the bacterial and archaeal components of the microbiota has revealed significant contributions in energy balance, bowel function, immunologic function, sensory perception, glycemic control, and blood pressure regulation. Elucidating the complex interactions between the microbiota and their associated epithelial, immune, and neural cells may provide mechanistic insights and a rational basis for our belief that dietary consumption of probiotic microorganisms and prebiotics produces health benefits.

Postoperative Crohn’s disease recurrence: A practical approach

Crohn's disease is a chronic inflammatory condition that may involve any segment of the gastrointestinal tract. Although several drugs have proven efficacy in inducing and maintaining disease in remission, resectional surgery remains as a cornerstone in the management of the disease, mainly for the treatment of its stenosing and penetrating complications. However, the occurrence of new mucosal (endoscopic) lesions in the neoterminal ileum early after surgery is almost constant, it is followed in the mid-term by clinical symptoms and, in a proportion of patients, repeated intestinal resections are required. Pathogenesis of postoperative recurrence (POR) is not fully understood, but luminal factors (commensal microbes, dietary antigens) seem to play an important role, and environmental and genetic factors may also have a relevant influence. Many studies tried to identify clinical predictors for POR with heterogeneous results, and only smoking has repeatedly been associated with a higher risk of POR. Ileocolonoscopy remains as the gold standard for the assessment of appearance and severity of POR, although the real usefulness of the available endoscopic score needs to be revisited and alternative techniques are emerging. Several drugs have been evaluated to prevent POR with limited success. Smoking cessation seems to be one of the more beneficial therapeutic measures. Aminosalicylates have only proved to be of marginal benefit, and they are only used in low-risk patients. Nitroimidazolic antibiotics, although efficient, are associated with a high rate of intolerance and might induce irreversible side effects when used for a long-term. Thiopurines are not widely used after ileocecal resection, maybe because some concerns in giving immunomodulators in asymptomatic patients still remain. In the era of biological agents and genetic testing, a well-established preventive strategy for POR is still lacking, and larger studies to identify good clinical, serological, and genetic predictors of early POR as well as more effective drugs (or drug combinations) are needed.

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

OBJECTIVE

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

DESIGN

A meta-analysis of controlled clinical trials.

METHODS

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

RESULT

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

CONCLUSION

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

The emerging therapeutic role of probiotics in inflammatory bowel disease

Nonpathogenic bacteria in a genetically susceptible individual play a suggestive role in the pathogenesis of inflammatory bowel disease (IBD). Probiotics are living organisms that exert a protective effect on intestinal mucosa. Although evidence supporting their use for inducing or maintaining remission of IBD remains limited, it may be reasonable to use probiotics as an adjunct to standard therapy for mild-to-moderate disease. Genetically modified probiotics may provide novel delivery methods of therapeutic payloads to inflamed intestinal mucosa. This review focuses on the emerging use of probiotics in the treatment of IBD.

Probiotic Lactobacillus reuteri suppress proinflammatory cytokines via c-Jun

BACKGROUND

Differential immunoregulatory capabilities of probiotic Lactobacillus were explored in the context of pediatric Crohn's disease. Experimental strategies addressed molecular mechanisms of tumor necrosis factor (TNF) suppression in activated macrophages by transcriptional regulation.

METHODS

Secreted factors produced by probiotic Lactobacillus reuteri strains were harvested and tested with human monocytes and macrophages. Quantitative immunoassays and real-time reverse-transcriptase polymerase chain reaction (RT-PCR) were used to examine relative quantities of human cytokines and TNF mRNA, respectively, and reporter assays assessed transcriptional regulation of TNF by probiotics. DNA-protein macroarrays interrogated probiotic-mediated effects on transcription factor activation. Finally, enzyme-linked immunosorbent assays (ELISAs) and immunoblots examined the involvement of the specific transcription factor AP-1 and its components.

RESULTS

Probiotic L. reuteri strain ATCC PTA 6475 demonstrated the ability to potently suppress human TNF production by lipopolysaccharide-activated monocytes and primary monocyte-derived macrophages from children with Crohn's disease. Quantities of the chemokine MCP-1/CCL2 were also reduced by probiotic L. reuteri strain ATCC PTA 6475 in macrophages of children in remission. Quantitative real-time RT-PCR and luciferase reporter assays showed that transcriptional regulation of human TNF was a primary mechanism of probiotic-mediated immunomodulation. Probiotic L. reuteri suppressed TNF transcription by inhibiting activation of MAP kinase-regulated c-Jun and the transcription factor, AP-1.

CONCLUSIONS

Human TNF and MCP-1 suppression by probiotic L. reuteri was strain-dependent, and the activation of c-Jun and AP-1 represent primary targets for probiotic-mediated suppression of TNF transcription. This report emphasizes the clonal nature of immunoprobiosis and delineation of a specific immunomodulatory mechanism for probiotic strain selection in future inflammatory bowel disease-oriented clinical trials.

Probiotics for induction of remission in Crohn's disease

BACKGROUND

Crohn's disease has a high morbidity and there is no known cure. Current treatments have multiple side effects and an effective treatment with minimal side effects is desired. Probiotics have been proposed as such a treatment but their efficacy is undetermined. There is some evidence that probiotics are effective in other conditions affecting the gastrointestinal tract and they are popular with patients. They are thought to work through competitive action with commensal and pathogenic flora, influencing the immune response.

OBJECTIVES

To determine if there is any evidence for the efficacy of probiotics for the induction of remission in Crohn's disease.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 1, 2007), MEDLINE (1966 to 2007), Excerpta Medica/EMBASE (1974 to 2007), CINAHL (1982-2007) and the Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders Group Specialised Trial Register were searched. Manufacturers of probiotics were also contacted to identify any unpublished trials. References of trials were also searched for any additional trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compared probiotics against placebo or any other intervention for the induction of remission in Crohn's disease were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of methodological quality of included studies were independently performed by two authors. The main outcome measure was the occurrence of clinical remission. Odds ratios and 95% confidence intervals were calculated for dichotomous outcomes.

MAIN RESULTS

One small study (n = 11) met the inclusion criteria and was included in the review. There were some methodological concerns with this study. Four of 5 patients in the probiotic group achieved remission compared to 5 of 6 in the placebo group (OR 0.80; 95% CI 0.04 to 17.20).

AUTHORS' CONCLUSIONS

There is insufficient evidence to make any conclusions about the efficacy of probiotics for induction of remission in Crohn's disease. There is a lack of well designed RCTs in this area and further research is needed.

Probiotics in the treatment of human inflammatory bowel diseases: update 2008

Probiotic research and clinical trials have been forging ahead over the last decade. Although much has been learnt in relation to probiotic intestinal epithelial-mucosal immune interactions, the evidence for substantial clinical efficacy of probiotics continues to progress much slower. This review outlines the probiotic clinical studies before 2005 that formed the foundation of probiotic clinical trials in inflammatory bowel disease and then examines indepth those inflammatory bowel disease probiotic clinical trials published after 2005 that are leading to new understanding of the role of probiotics in the induction and remission of inflammatory bowel disease in humans.

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.

Microbial host interactions in IBD: implications for pathogenesis and therapy

Crohn's disease (CD), ulcerative colitis (UC), and pouchitis appear to be caused by pathogenic T-cell responses to discrete antigens from the complex luminal microbiota, with susceptibility conferred by genetic polymorphisms that regulate bacterial killing, mucosal barrier function, or immune responses. Environmental triggers initiate or reactivate inflammation and modulate genetic susceptibility. New pathogenesis concepts include defective bacterial killing by innate immune cells in CD, colonization of the ileum in CD with functionally abnormal Escherichia coli that adhere to and invade epithelial cells and resist bacterial killing, and alterations in enteric microbiota composition in CD, UC, and pouchitis detected by molecular probes. The considerable therapeutic potential of manipulating the enteric microbiota in inflammatory bowel disease patients has not been realized, probably due to failure to recognize heterogenic disease mechanisms that require individualized use of antibiotics, probiotics, prebiotics, combination therapies, and genetically engineered bacteria to restore mucosal homeostasis.

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.

Probiotics and prebiotics in dietetics practice

Probiotics and prebiotics share a unique role in human nutrition, largely centering on manipulation of populations or activities of the bacteria that colonize our bodies. Benefits of regular consumption of probiotics or prebiotics include enhanced immune function, improved colonic integrity, decreased incidence and duration of intestinal infections, down-regulated allergic response, and improved digestion and elimination. Research has shown that probiotics and prebiotics may be useful in achieving these and other positive effects, provided that proper strain, product selection, and dosing guidelines of commercial products are followed. There is a need to consolidate the basic and applied research on probiotics and prebiotics into useful tools for food and nutrition professionals. Information on probiotic species, applications for specific strains, dosages and forms, safety, and shelf life is not sufficiently summarized to allow practical and consistent recommendations to be made by most food and nutrition professionals. In addition, prebiotic fibers-although providing nutraceutical and nutritional value-are a group of diverse carbohydrate ingredients that are poorly understood in regard to their origin, fermentation profiles, and dosages required for health effects. The science and practice-based guidelines presented here will enhance clinician and client understanding of probiotics and prebiotics, with the aim of improving appropriate recommendation and informed use of these emerging dietary ingredients and the products containing them.

Probiotics in clinical practice: an overview

The observation that intestinal bacterial microflora might be able to influence immune system surveillance through changed nutritional habits has raised awareness of the role of probiotics. These are live microorganisms that are able to reach the gastrointestinal tract and alter its microfloral composition, producing beneficial health effects when consumed in adequate amounts. Recent clinical trials have evaluated the clinical effectiveness of probiotics in the treatment and prevention of a wide range of acute and chronic gastrointestinal diseases, and also non-gastrointestinal diseases, such as atopy, respiratory infections, vaginitis and hypercholesterolaemia. Probiotic supplements are generally regarded as safe because the microorganisms they contain are identical to those found in human gastrointestinal and vaginal microflora. Guidelines on the use of probiotics in the clinical setting require periodical updates for the latest data to be included in clinical applications. The purpose of this clinical report is to review current evidence on the use of probiotics in a variety of gastrointestinal and non-gastrointestinal conditions.

Impact of azathioprine on the prevention of postoperative Crohn's disease recurrence: results of a prospective, observational, long-term follow-up study

BACKGROUND

Postoperative recurrence (PR) occurs early after intestinal resection in >75% of Crohn's disease (CD) patients. No well-established strategy for long-term PR prevention is available. The aim was to prospectively evaluate the long-term endoscopic and clinical outcomes of postoperative CD on maintenance treatment with azathioprine (AZA), especially in patients who developed endoscopic lesions confined to the ileocolic anastomosis.

METHODS

Long-term AZA therapy (2-2.5 mg/kg/day) was initiated immediately after surgery in 56 consecutive patients who underwent a curative intestinal resection. Clinical and biological assessments every 3 months, as well as yearly endoscopic evaluation, were performed until the end of the study or clinical PR (CPR).

RESULTS

Thirty-seven patients (70%) showed mucosal lesions at endoscopy after a median of 12 months (range 12-60); however, in 15 of these patients lesions were confined to the anastomosis and only 6 showed endoscopic progression, but none of them developed CPR. Among the remaining 22 patients with endoscopic PR (EPR), 23% suffered a CPR during follow-up. Thirty percent of patients remained free of EPR after a median follow-up of 33 months (range 12-84). The cumulative probability of EPR was 44%, 53%, 69%, and 82%, at 1, 2, 3, and 5 years, respectively. No predictive factors of EPR were found.

CONCLUSIONS

Early postoperative use of AZA seems to delay EPR development in comparison to historical series or placebo groups in randomized controlled trials. Although usually considered as endoscopic recurrence, those lesions confined to the ileocolonic anastomosis are not likely to progress or to become symptomatic in the short term.

Management of postoperative Crohn's disease

Three-quarters of the patients with Crohn's disease (CD) require surgery involving a resection in the course of their disease. Even if all macroscopically involved bowel is removed, the disease usually recurs proximal to, and at, the anastomosis. This often leads to the recurrent need for treatment of active disease, complications, and reoperation. Ileocolonoscopy has an important place in the assessment of postoperative Crohn's recurrence. The limited available data regarding drug therapy in the postoperative setting suggest that optimal management should include identification of high-risk patients earlier and more widespread use of immunosuppressive therapy than was previously recommended, and colonoscopic monitoring. Such strategies to prevent recurrence then need to be prospectively evaluated. This article examines the evidence for medical prophylaxis of postoperative CD, and proposes a treatment strategy based on current evidence.

Probiotics: sorting the evidence from the myths

Probiotics consist of yeast or bacteria, especially lactic acid bacteria. They are available as capsules, powder, fermented milks or yoghurts. Probiotics exhibit strain-specific differences in their resistance to acid and bile, ability to colonise the gastrointestinal tract, clinical efficacy, and benefits to the health of the host. There is level I evidence for the use of probiotics in treating acute infectious diarrhoea and preventing antibiotic-associated diarrhoea, with Lactobacillus rhamnosus GG and Saccharomyces boulardii having the most evidence to support their use for these conditions. There is level II evidence that S. boulardii combined with high-dose vancomycin is more effective than the antibiotic alone in preventing recurrent Clostridium difficile diarrhoea. There is level I evidence that probiotics prevent traveller's diarrhoea. There is level I evidence for use of the high-potency probiotic VSL#3 in preventing pouchitis, and level II evidence for this agent in preventing relapse in patients with ulcerative colitis. Probiotics are generally regarded as safe and well tolerated. Some probiotics may be contraindicated in patients who are immunocompromised or have severe underlying illness, as they have been reported to cause fungaemia and bacteraemia.