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

Probiotics and prebiotics in inflammatory bowel disease: microflora 'on the scope'

The intestinal microflora is a large bacterial community that colonizes the gut, with a metabolic activity equal to an organ and various functions that affect the physiology and pathology of the host's mucosal immune system. Intestinal bacteria are useful in promotion of human health, but certain components of microflora, in genetically susceptible individuals, contribute to various pathological disorders, including inflammatory bowel disease. Clinical and experimental observations indicate an imbalance in protective and harmful microflora components in these disorders. Manipulation of gut flora to enhance its protective and beneficial role represents a promising field of new therapeutic strategies of inflammatory bowel disease. In this review, we discuss the implication of gut flora in the intestinal inflammation that justifies the role of probiotics and prebiotics in the prevention and treatment of inflammatory bowel disease and we address the evidence for therapeutic benefits from their use in experimental models of colitis and clinical trials.

Probiotics in the management of colonic disorders

Probiotics have been used in humans for almost a century and widely recommended for the treatment of a variety of ills assumed to be of colonic origin, including diarrhea, constipation, bloating, and flatulence. More recently, probiotics have been evaluated in the management of specific colonic disorders such as inflammatory bowel disease, irritable bowel syndrome, and Clostridium difficile colitis. It is evident that no two probiotics are exactly alike; why then should we expect reproducible results from studies that employ different species or strains, variable formulations, and diverse dosing schedules? When probiotics have been studied with the rigor appropriate to a new therapeutic modality, some coherent results have emerged: specific strains are effective in certain diarrheal states, irritable bowel syndrome, ulcerative colitis, and pouchitis, as well as in the prevention of C. difficile-related colitis. Even here, not to mention other colonic disorders, further adequately powered and appropriately designed trials are needed.

Novel therapeutic options in the inflammatory bowel disease world

Advances in the understanding of the pathogenesis of inflammatory bowel disease have encouraged the development of many new therapies targeted at specific and non-specific mediators of the inflammatory bowel disease inflammatory pathway. The role of these therapies, including novel anti-tumour necrosis factor-alpha agents, anti-adhesion molecules, recombinant cytokines, myeloid growth factors, helminths, and probiotics, in the management of paediatric onset inflammatory bowel disease is promising and warrants further investigation.

Crohn's disease

INTRODUCTION

Crohn's disease is a long-term chronic condition of the gastrointestinal tract. It is characterised by transmural, granulomatous inflammation that occurs in a discontinuous pattern, with a tendency to form fistulae. The cause is unknown but may depend on interactions between genetic predisposition, environmental triggers, and mucosal immunity.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of medical treatments in adults to induce remission in Crohn's disease? What are the effects of lifestyle interventions in adults with Crohn's disease to maintain remission? What are the effects of surgical interventions in adults with small-bowel Crohn's disease to induce remission? What are the effects of surgical interventions in adults with colonic Crohn's disease to induce remission? What are the effects of medical interventions to maintain remission in adults with Crohn's disease; and to maintain remission following surgery? We searched: Medline, Embase, The Cochrane Library and other important databases up to March 2006 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 60 systematic reviews, RCTs, or observational studies that met our inclusion criteria.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: aminosalicylates, antibiotics, azathioprine/mercaptopurine, ciclosporin, corticosteroids (oral), enteral nutrition, fish oil, infliximab, methotrexate, probiotics, resection, segmental colectomy, smoking cessation, and strictureplasty.

Evidence for the use of probiotics and prebiotics in inflammatory bowel disease: a review of clinical trials

Human subjects and their enteric microbiota have evolved together to reach a state of mutual tolerance. Mounting evidence from both animal models and human studies suggests that inflammatory bowel disease (IBD) represents a malfunction of this relationship. The enteric microecology therefore represents an attractive therapeutic target with few side effects. Probiotics and prebiotics have been investigated in clinical trials as treatments for IBD, with conflicting results. The evidence for the use of probiotics in the management of pouchitis is persuasive and several studies indicate their effectiveness in ulcerative colitis. Trials of probiotics and prebiotics in Crohn's disease are less convincing. However, methodologies vary widely and a range of probiotic, prebiotic and combination (synbiotic) treatments have been tested in a variety of patient groups with an assortment of end points. Conclusions about any one treatment in a specific patient group can therefore only be drawn on evidence from relatively small numbers of patients. The present article reviews the role of the intestinal microbiota in the pathogenesis of IBD and addresses the clinical evidence for the therapeutic manipulation of bowel microbiota using probiotics, prebiotics and synbiotics in IBD.

Probiotics for preventing relapse or recurrence in Crohn's disease involving the ileum: Are there reasons for failure?

In contrast to ulcerative colitis and pouchitis, benefits of probiotic therapy in preventing recurrence/relapse in Crohn's disease (mostly involving the ileum) are far from being proven. The lack of response in this setting does not seem attributable to a lower relevance of dysbiosis in ileal Crohn's disease, since this - or at least the presence of increased mucosal amounts of potentially pathogen bacteria - has been proven to occur in the ileum of Crohn's disease patients. Available data indicate that whereas in ulcerative colitis (and to a lesser extent in colonic Crohn's disease) the innate immune response is enhanced, it is constitutively depressed in ileal Crohn's disease. Therefore, attempts to modify the composition of intestinal microflora in colonic IBD or pouchitis by means of probiotics do make sense. In contrast, supplying additional bacteria (even being probiotics) to an ileum with decreased antibacterial defence does not seem reasonable. In fact, the presence of intestinal contents has been reported to be related to postoperative recurrence in ileo-caecal Crohn's disease, and antibiotic treatment in effective to prevent its development.

Operative management of small bowel Crohn's disease

Despite advances in medical treatment, most patients who have Crohn's disease of the small intestine need surgery at some point during the course of their disease. Surgery is currently indicated for intractable disease and complications of the disease (strictures, abscesses, fistulas, hemorrhage). There is increasing interest in nonsurgical and minimal access strategies of dealing with complicated disease, however. These new approaches may enable postponement of surgery to a more favorable time, or conversion of a two-stage procedure involving a stoma to a one-stage resection with anastomosis. A continuing challenge is prevention of disease recurrence postoperatively.

[Probiotics and prebiotics in inflammatory bowel disease]

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

Patchy distribution of mucosal lesions in ileal Crohn's disease is not linked to differences in the dominant mucosa-associated bacteria: a study using fluorescence in situ hybridization and temporal temperature gradient gel electrophoresis

BACKGROUND

The mucosa-associated bacteria (MAB) are suspected of being involved in the pathogenesis of Crohn's disease. We analyzed and compared the MAB in noninflamed and inflamed ileal mucosa of Crohn's disease patients (n = 22).

METHODS

Tissue samples from the inflamed ileal mucosa and from the adjacent noninflamed ileal mucosa were taken from surgical resection specimens. The MAB were investigated using fluorescence in situ hybridization with 7 group-specific probes and temporal temperature gradient gel electrophoresis (TTGE).

RESULTS

Samples from both noninflamed and inflamed mucosa were obtained from 15 patients. The distribution of the bacterial populations was not different between noninflamed and inflamed mucosa. The Bacteroidetes phylum was dominant and accounted for 29% of MAB (0%-74%) in noninflamed tissues and 32% (0%-70%) in inflamed areas. The gamma Proteobacteria represented 12% (0%-70%) of MAB both in noninflamed and inflamed areas. The Clostridium coccoides group (Firmicutes phylum) represented 15% of MAB in noninflamed tissues versus 7% in inflamed areas. For most of the patients the similarity index between TTGE paired profiles was very high.

CONCLUSION

The dominant MAB do not differ between noninflamed and inflamed ileal mucosa in Crohn's disease. This argues against a localized dysbiosis to explain the patchy distribution of mucosal lesions.

Therapeutic effect and mechanism of probiotics on inflammatory bowel disease

Inflammatory bowel disease (IBD) includes ulcerative colitis (UC) and Crohn's disease (CD). Many studies demonstrate an involvement of intestinal microflora in the pathogenesis of IBD. Tissue damages can result from dysregulated immune response to intestinal bacteria in genetically susceptible individuals. Therefore, alteration of the intestinal microflora may represent a feasible therapeutic approach for IBD. Probiotics can change the proportion of intestinal microflora, improve the function of intestinal epithelial barrier, prevent intestinal bacterial translocation and alleviate the inflammation degree. In this article, we reviewed the effect of probiotics in the treatments of IBD and its mechanism.

Prebiotics, probiotics, and dietary fiber in gastrointestinal disease

Microecology of the gastrointestinal tract is the physiologic basis for the effect of dietary fiber, prebiotics and probiotics on the host. The ecology consists of the gastrointestinal tract, primarily the intestines, the foods that are fed into the tract, and the flora living within. Within this ecology, normal flora and probiotics, ferment dietary fiber and prebiotics to produce short chain fatty acids and substances that are absorbed and effect the host at the intestinal level and systemically. In this review, we will discuss the effects of prebiotics, probiotics and dietary fiber in gastrointestinal disorders and diseases.

Gut microbiota: mining for therapeutic potential

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

Fibrogenesis in Crohn's disease

INTRODUCTION

Over one-third of patients with Crohn's disease (CD) will develop an intestinal stricture and the great majority of these will require at least one surgical procedure. While the pathogenesis of inflammation in CD has been extensively investigated, knowledge of stricture pathogenesis remains limited. The aim of this review is to discuss the current understanding of fibrogenesis in CD and to outline potential directions in research and therapeutics.

METHODS

The electronic literature (January 1966 to May 2006) on CD-associated fibrosis was reviewed. Further references were obtained by cross-referencing from key articles.

RESULTS

CD-associated fibrosis results from chronic transmural inflammation and a complex interplay among intestinal mesenchymal cells, cytokines, and local inflammatory cells. The fibroblast is the key cell type mediating stricture formation. The cytoarchitecure of the bowel wall is altered with disruption of the muscularis mucosa, thickening of the muscularis propria, and deposition of collagen throughout. The cytokine TGF-beta appears critical in this process, acting to increase growth factor and extracellular matrix (ECM) production and dysregulate ECM turnover. Potential therapeutic interventions are likely to concentrate on modulating down-stream targets of TGF-beta.

CONCLUSIONS

Greater understanding of the biology of fibrostenosis is likely to yield significant advances in our ability to care for patients with stricturing CD. Potential dividends of this approach include identification of novel therapeutic targets and biomarkers useful for prognostication and therapeutic monitoring.

Failure of Synbiotic 2000 to prevent postoperative recurrence of Crohn's disease

Complications of Crohn's disease (CD) lead to surgery in about 70-90% of patients. The majority of patients suffer from relapse of the disease. Colonic bacteria are essential to the development of CD. Therefore, a rationale exists in trying to prevent relapse by manipulation of gut microflora. This is feasible by treatment with probiotics or antibiotics. Synbiotic 2000 is a cocktail containing 4 probiotic species and 4 prebiotics. It is rational to pursue that it could be effective in preventing postoperative disease. We sought to check weather treatment with Synbiotic 2000 could prevent postoperative recurrence in patients with CD. This was a prospective multicenter, randomized study. Patients were randomized to active treatment or placebo in a 2:1 ratio. Follow-up consisted of endoscopic, clinical, and laboratory parameters. Thirty patients were enrolled. No differences were found between the 2 treatment groups regarding gender, age at diagnosis, age at surgery, weight, smoking status, type of disease, length of the resected segment, or medical treatment prior to surgery. No difference in either endoscopic or clinical relapse rate was found between patients treated with once daily dose of Synbiotic 2000 or placebo. In our small study, Synbiotic 2000 had no effect on postoperative recurrence of patients with CD. Larger studies in patients with the inflammatory type of CD undergoing surgery, using higher doses of probiotics cocktail might prove effective.

The role of antibiotic and probiotic therapies in current and future management of inflammatory bowel disease

Abundant evidence indicates that the intestinal microflora have a role in the pathogenesis of inflammatory bowel disease (IBD). The composition of the gut microflora is altered in IBD patients with increased "pathogenic" bacteria and decreased bifidobacteria and lactobacilli. In light of this dysbiosis, various methods have been examined to alter the composition of the intestinal microflora, including the administration of antibiotics and introduction of probiotic species. This article summarizes studies evaluating the efficacy of antibiotics and probiotics in the induction and maintenance of remission of ulcerative colitis, Crohn's disease, and pouchitis.

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.

Review article: can post-operative recurrence in Crohn's disease be prevented?

The decision regarding prophylactic treatment after surgery in Crohn's disease (CD) requires a good estimation of the risk of recurrence. It is also important to consider the consequences of recurrence for the patient, and the risks and benefits of treatment, bearing in mind that it will be given over a long period. Several drugs have been tried to decrease the risk of recurrence. Corticosteroids and budesonide have proved to be ineffective. Mesalazine has significant efficacy in some, but not all trials, and a meta-analysis has established that it decreases the absolute risk by 10-15% after 1-2 years. Mercaptopurine seemed to be effective in a recent study. Metronidazole and ornidazole have significant efficacy, but cannot be tolerated for long periods. Probiotics represent a new approach, but evidence for their efficacy in CD is still lacking. In the past, the strategy was to give no treatment until clinical recurrence. Another approach is to give no treatment, and then to treat the patient according to severity of endoscopic recurrence. Alternative strategies include treating all patients with mesalazine until either severe endoscopic or clinical recurrence occurs, and then to use azathioprine/mercaptopurine, or to give azathioprine/mercaptopurine immediately, especially in high-risk patients.

Review article: the intestinal lumen as a therapeutic target in inflammatory bowel disease

Undigested carbohydrates reaching the colon can act as competitors for epithelial bacterial receptors, making it difficult for noncommensal bacteria to adhere to them. On the contrary, fermentation of these carbohydrates by anaerobic flora produces - among other substrates - butyrate that is involved in numerous important metabolic processes. These include the provision of energy to the colonocytes, the enhancement of sodium and water absorption and the synthesis of mucus and cell membranes. In addition, butyrate inhibits the nuclear translocation of the transcription factor NFkappaB, which exerts a potent anti-inflammatory activity. Clinical experience with probiotics in inflammatory bowel disease (IBD) is controversial. Whereas some probiotic preparations appear to be useful in ulcerative colitis (UC) and pouchitis, most attempts to use probiotics for treating or preventing recurrence in Crohn's disease have failed. It should be pointed out that - unlike in the small bowel - the colon and ileal pouches are well-established microbiological ecosystems with increasing amounts of a wide variety of bacterial strains. These bacterial strains have a high degree of metabolic interaction with luminal nutrients and a greater probability of developing dysbiosis. With this in mind, the rationale for using pre- and probiotics appears to be stronger for colonic IBD (UC or Crohn's colitis) and pouchitis than for IBD mostly involving the small bowel.

Review article: the role of bacteria in onset and perpetuation of inflammatory bowel disease

We review the evidence that strongly suggests a role of the intestinal microbiota in the onset and perpetuation of inflammatory bowel disease (IBD). Experimental studies consisted of suppressing micro-organisms from the microbiota (using germ-free or gnotoxenic animals or antibiotics), introducing new micro-organisms or microbial components (e.g. probiotics, CpG-DNA) or selectively increasing some endogenous bacteria (e.g. using prebiotics). Intervention studies were performed in patients or animal models of spontaneous or chemically-induced colitis. Information was also obtained from observational studies that described the composition of the faecal and mucosal microbiota at various stages of the disease process and in controls. Many have used culture-independent techniques that identify bacteria based on the nucleic acid sequence of ribosomal RNA molecules. Microbiota in patients with IBD seem to be characterized by high concentrations of bacteria in contact with the mucosa, instability, the presence of high numbers of unusual bacteria and sometimes a reduction in the biodiversity. Studies searching for a generalized or localized dysbiosis in IBD are discussed, as well as those trying to identify bacterial molecules and receptors, which may be implicated in triggering the inflammatory process.

Inflammatory Bowel Disease: Pandora's Box, Present and Future

Current treatment of inflammatory bowel disease is rather effective through it is only working in symptomatic fashion. Most recombinant "biologicals" have not been an overwhelming success. Infliximab has shown clinically relevant efficacy and is used in patients not responding to the standards. Alternatives such as modulating the bacterial-epithelial interaction, tightening of the mucosal barrier and maybe even immunostimulation should be studied since most recent finding on etiology and pathophysiology point to a disturbed barrier with consequent abnormal bacterial epithelial interaction as the main problem in the IBD syndrome. We still need to learn much but we should not focus only on immunosuppressive systems.

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.

Probiotics for Crohn's disease: what have we learned?

Probiotics do not seem to be a therapeutic option for patients with Crohn's disease, either in the acute phase or for maintenance