Mesalazine (5-aminosalicylic acid) alters faecal bacterial profiles, but not mucosal proteolytic activity in diarrhoea-predominant irritable bowel syndrome

The colon targeting efficacies of mesalazine medications and their impacts on the gut microbiome

Successful treatment of ulcerative colitis (UC) is highly dependent on several parameters, including dosing regimen and the ability to deliver drugs to the disease site. In this study two strategies for delivering mesalazine (5-aminosalicylic acid, 5-ASA) to the colon were compared in an advanced in vitro model of the human gastrointestinal (GI) tract, the SHIME® system. Herein, a prodrug strategy employing bacteria-mediated drug release (sulfasalazine, Azulfidine®) was evaluated alongside a formulation strategy that utilised pH and bacteria-mediated release (5-ASA, Octasa® 1600 mg). SHIME® experiments were performed simulating both the GI physiology and colonic microbiota under healthy and inflammatory bowel disease (IBD) conditions, to study the impact of the disease state and ileal pH variability on colonic 5-ASA delivery. In addition, the effects of the products on the colonic microbiome were investigated by monitoring bacterial growth and metabolites. Results demonstrated that both the prodrug and formulation approaches resulted in a similar percentage of 5-ASA recovery under healthy conditions. On the contrary, during experiments simulating the GI physiology and microbiome of IBD patients (the target population) the formulation strategy resulted in a higher proportion of 5-ASA delivery to the colonic region as compared to the prodrug approach (P < 0.0001). Interestingly, the two products had distinct effects on the synthesis of key bacterial metabolites, such as lactate and short chain fatty acids, which varied according to disease state and ileal pH variability. Further, both 5-ASA and sulfasalazine significantly reduced the growth of the faecal microbiota sourced from six healthy humans. The findings support that the approach selected for colonic drug delivery could significantly influence the effectiveness of UC treatment, and highlight that drugs licensed for UC may differentially impact the growth and functioning of the colonic microbiota.

Gut microb-aging and its relevance to frailty aging

This review explores 'microb-aging' in the gut and its potential link to frailty aging. We explore this connection through alterations in microbiota's taxonomy and metabolism, as well as with concepts of ecological resilience, pathobionts emergence, and biogeography. We examine microb-aging in interconnected body organs, emphasizing the bidirectional relationship with 'inflammaging'. Finally, we discuss how targeting microb-aging could improve screening, diagnostic, and therapeutic approaches in geriatrics.

Interplay between inflammatory bowel disease therapeutics and the gut microbiome reveals opportunities for novel treatment approaches

Inflammatory bowel disease (IBD) is a complex heterogeneous disorder defined by recurring chronic inflammation of the gastrointestinal tract, attributed to a combination of factors including genetic susceptibility, altered immune response, a shift in microbial composition/microbial insults (infection/exposure), and environmental influences. Therapeutics generally used to treat IBD mainly focus on the immune response and include non-specific anti-inflammatory and immunosuppressive therapeutics and targeted therapeutics aimed at specific components of the immune system. Other therapies include exclusive enteral nutrition and emerging stem cell therapies. However, in recent years, scientists have begun to examine the interplay between these therapeutics and the gut microbiome, and we present this information here. Many of these therapeutics are associated with alterations to gut microbiome composition and functionality, often driving it toward a "healthier profile" and preclinical studies have revealed that such alterations can play an important role in therapeutic efficacy. The gut microbiome can also improve or hinder IBD therapeutic efficacy or generate undesirable metabolites. For certain IBD therapeutics, the microbiome composition, particularly before treatment, may serve as a biomarker of therapeutic efficacy. Utilising this information and manipulating the interactions between the gut microbiome and IBD therapeutics may enhance treatment outcomes in the future and bring about new opportunities for personalised, precision medicine.

Microbiota-sensitive drug delivery systems based on natural polysaccharides for colon targeting

Colon targeting is an ongoing challenge, particularly for the oral administration of biological drugs or local treatment of inflammatory bowel disease (IBD). In both cases, drugs are known to be sensitive to the harsh conditions of the upper gastrointestinal tract (GIT) and, thus, must be protected. Here, we provide an overview of recently developed colonic site-specific drug delivery systems based on microbiota sensitivity of natural polysaccharides. Polysaccharides act as a substrate for enzymes secreted by the microbiota located in the distal part of GIT. The dosage form is adapted to the pathophysiology of the patient and, thus, a combination of bacteria-sensitive and time-controlled release or pH-dependent systems can be used for delivery.

Current evidence and clinical relevance of drug-microbiota interactions in inflammatory bowel disease

Background

Inflammatory bowel disease (IBD) is a chronic relapsing-remitting disease. An adverse immune reaction toward the intestinal microbiota is involved in the pathophysiology and microbial perturbations are associated with IBD in general and with flares specifically. Although medical drugs are the cornerstone of current treatment, responses vary widely between patients and drugs. The intestinal microbiota can metabolize medical drugs, which may influence IBD drug (non-)response and side effects. Conversely, several drugs can impact the intestinal microbiota and thereby host effects. This review provides a comprehensive overview of current evidence on bidirectional interactions between the microbiota and relevant IBD drugs (pharmacomicrobiomics).

Methods

Electronic literature searches were conducted in PubMed, Web of Science and Cochrane databases to identify relevant publications. Studies reporting on microbiota composition and/or drug metabolism were included.

Results

The intestinal microbiota can both enzymatically activate IBD pro-drugs (e.g., in case of thiopurines), but also inactivate certain drugs (e.g., mesalazine by acetylation via N-acetyltransferase 1 and infliximab via IgG-degrading enzymes). Aminosalicylates, corticosteroids, thiopurines, calcineurin inhibitors, anti-tumor necrosis factor biologicals and tofacitinib were all reported to alter the intestinal microbiota composition, including changes in microbial diversity and/or relative abundances of various microbial taxa.

Conclusion

Various lines of evidence have shown the ability of the intestinal microbiota to interfere with IBD drugs and vice versa. These interactions can influence treatment response, but well-designed clinical studies and combined in vivo and ex vivo models are needed to achieve consistent findings and evaluate clinical relevance.

Progress in research of low-grade inflammation in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common intestinal disease with a prevalence of 10%-15%. However, its pathophysiology is still not completely clear, and it has long been considered as a functional disease. In recent years, it has been found that low-grade inflammation plays a pathogenic role in IBS. Studies have confirmed that there is persistent mucosal inflammation at the microscopic and molecular levels. This review discusses the evidence, role, and clinical relevance of mucosal inflammation in IBS. In addition to mucosal inflammation, neuroinflammation may lead to changes in neuroendocrine pathways and glucocorticoid receptor genes through the "gut-brain" axis, and thus cause IBS through proinflammatory phenotype and hypothalamic pituitary adrenal axis and 5-hydroxytryptamine dysfunction. The observation that IBS patients can benefit from anti-inflammatory therapy also confirms that IBS is associated with inflammation.

Dextran Sulphate Sodium Acute Colitis Rat Model: A Suitable Tool for Advancing Our Understanding of Immune and Microbial Mechanisms in the Pathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a group of disorders causing inflammation in the digestive tract. Recent data suggest that dysbiosis may play a pivotal role in the IBD pathogenesis. As microbiome-based therapeutics that modulate the gut ecology have been proposed as a novel strategy for preventing IBD, the aim of presenting study was to evaluate the dextran sulphate sodium (DSS) rat model mainly in terms of microbial shifts to confirm its suitability for dysbiosis study in IBD. Acute colitis was induced using 5% DSS solution for seven days and rats were euthanized five days after DSS removal. The faecal/caecal microbiota was analyzed by next generation sequencing. Disease activity index (DAI) score was evaluated daily. Blood and colon tissue immunophenotyping was assessed by flow cytometry and histological, haematological, and biochemical parameters were also evaluated. The colitis induction was reflected in a significantly higher DAI score and changes in all parameters measured. This study demonstrated significant shifts in the colitis-related microbial species after colitis induction. The characteristic inflammation-associated microbiota could be detected even after a five day-recovery period. Moreover, the DSS-model might contribute to an understanding of the effect of different treatments on extraintestinal organ impairments. The observation that certain bacterial species in the gut microbiota are associated with colitis raises the question of whether these organisms are contributors to, or a consequence of the disease. Despite some limitations, we confirmed the suitability of DSS-induced colitis model to monitor microbial changes during acute colitis, in order to test attractive new microbiome-based therapies.

Belgian consensus on irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is characterised by recurrent abdominal pain related to defaecation or associated with altered stool frequency or consistency. Despite its prevalence, major uncertainties in the diagnostic and therapeutic management persist in clinical practice.

METHODS

A Delphi consensus was conducted by 20 experts from Belgium, and consisted of literature review and voting process on 78 statements. Grading of recommendations, assessment, development and evaluation criteria were applied to evaluate the quality of evidence. Consensus was defined as > 80 % agreement.

RESULTS

Consensus was reached for 50 statements. The Belgian consensus agreed as to the multifactorial aetiology of IBS. According to the consensus abdominal discomfort also represents a cardinal symptom, while bloating and abdominal distension often coexist. IBS needs subtyping based on stool pattern. The importance of a positive diagnosis, relying on history and clinical examination is underlined, while additional testing should remain limited, except when alarm features are present. Explanation of IBS represents a crucial part of patient management. Lifestyle modification, spasmolytics and water-solube fibres are considered first-line agents. The low FODMAP diet, selected probiotics, cognitive behavioural therapy and specific treatments targeting diarrhoea and constipation are considered appropriate. There is a consensus to restrict faecal microbiota transplantation and gluten-free diet, while other treatments are strongly discouraged.

CONCLUSIONS

A panel of Belgian gastroenterologists summarised the current evidence on the aetiology, symptoms, diagnosis and treatment of IBS with attention for the specificities of the Belgian healthcare system.

Risk factors for Clostridioides difficile infection in children and adolescents with inflammatory bowel disease: a systematic review and meta-analysis

BACKGROUND

Risk factors and consequences associated with Clostridioides difficile infection (CDI) in children and adolescents with inflammatory bowel disease (IBD) are still uncertain. We conduct a systematic review and meta-analysis to assess risk factors and outcomes associated with CDI in children and adolescents with IBD.

METHODS

PubMed, EMBASE and Cochrane Library databases were searched from inception to 24th February, 2021. Studies investigating risk factors, bowel surgery rate in pediatric IBD patients with and without CDI were included. Random-effects model was used for calculating summary estimates. Newcastle-Ottawa scale (NOS) was used for quality assessment.

RESULTS

Fourteen studies, comprising 17,114 patients, were included. There was a significant association between 5-aminosalicylic acid (5-ASA) use and CDI [odds ratio (OR) = 1.95, 95% confidence interval (CI) 1.26-3.03], with minimal heterogeneity (I² = 0.00%). Increased risk of active disease (OR = 4.66, 95% CI 2.16-10.07) were associated with CDI in those studies performed in high quality score (NOS > 6) and significantly higher CDI rates in studies conducted outside USA (OR = 2.94, 95% CI 1.57-5.58). The bowel surgery rate in IBD with CDI was 3.8-57.1%, compared to that in IBD without CDI (0-21.3%). All studies were of moderate to high quality.

CONCLUSIONS

5-ASA use and active disease might be risk factors associated with CDI in children and adolescents with IBD. Bowel surgery rates associated with CDI in IBD patients varied greatly. Large-scale clinical studies on CDI in children and adolescents with IBD are still needed to verify risk factors and outcomes.

A review of the biological and pharmacological activities of mesalazine or 5-aminosalicylic acid (5-ASA): an anti-ulcer and anti-oxidant drug

Mesalazine, also known as 5-aminosalicylic acid (5-ASA), is a synthetic drug from the family of nonsteroidal anti-inflammatory drugs (NSAIDs) used for inflammatory diseases of the gastrointestinal tract. However, 5-ASA has also been used for various other diseases due to its pharmacological effects, but they are usually scattered across various publications, which may limit further research and clinical use of this drug. This review is a summary of published information on the biological and pharmacological effects of 5-ASA with the aim of identifying its anti-oxidant role and medicinal use. 5-ASA data have been collected from 1987 to February 2021 using major databases such as Web of Science, PubMed, Elsevier, Wiley Online Library, Springer, Google Scholar, etc. According to research, the pharmacological and biological effects of 5-ASA include treatment of inflammatory bowel disease, and anti-oxidant, anti-inflammatory, antibacterial, antifungal, anticancer, anti-amyloid, gastric protection (gastroprotective), and antidiverticulosis properties. Numerous pharmacological studies have shown that 5-ASA is an anti-oxidant and anti-ulcer compound with high therapeutic potential that, if the appropriate dose is discovered, its chemical structure changes and its effectiveness is optimized, 5-ASA has been used experimentally for other diseases.

The relationship between gut microbiota and proteolytic activity in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disease that affects 3.8-9.2% of the world population. It affects the physiology and psychology of patients and increases the burden on families, the healthcare system, society, and economic development. Presently, a large number of studies have shown that compared to healthy individuals, the composition and diversity of gut microbiota in IBS patients have changed, and the proteolytic activity (PA) in fecal supernatant and colonic mucosa of IBS patients has also increased. These findings indicate that the imbalance of intestinal microecology and intestinal protein hydrolysis is closely related to IBS. Furthermore, the intestinal flora is a key substance that regulates the PA and is associated with IBS. The current review described the intestinal microecology and intestinal proteolytic activity of patients with IBS and also discussed the effect of intestinal flora on PA. In summary, this study proposed a pivotal role of gut microbiota and PA in IBS, respectively, and provided an in-depth insight into the diagnosis and treatment targets of IBS as well as the formulation of new treatment strategies for other digestive diseases and protease-related diseases.

Colonic Gene Expression and Fecal Microbiota in Diarrhea-predominant Irritable Bowel Syndrome: Increased Toll-like Receptor 4 but Minimal Inflammation and no Response to Mesalazine

Background/Aims

Diarrhea-predominant irritable bowel syndrome (IBS-D) has been previously associated with evidence of immune activation and altered microbiota. Our aim is to assess the effect of the anti-inflammatory agent, mesalazine, on inflammatory gene expression and microbiota composition in IBS-D.

Methods

We studied a subset of patients (n = 43) from a previously published 12-week radomized placebo-controlled trial of mesalazine. Mucosal biopsies were assessed by immunohistochemistry and reverse transcription-polymerase chain reaction for a range of markers of inflammation, altered permeability, and sensory receptors including Toll-like receptors (TLRs) at randomization after treatment. All biopsy data were compared to 21 healthy controls. Patient’s stool microbiota composition was analysed through 16S ribosomal RNA sequencing.

Results

We found no evidence of increased immune activation compared to healthy controls. However, we did find increased expression of receptors in both sensory pathways and innate immune response including TLR4. Higher TLR4 expression was associated with greater urgency. TLR4 expression correlated strongly with the expression of the receptors bradykinin receptor B2, chemerin chemokine-like receptor 1, and transient receptor potential cation channel, subfamily A, member 1 as well as TLR4’s downstream adaptor myeloid differentiation factor 88. Mesalazine had minimal effect on either gene expression or microbiota composition.

Conclusions

Biopsies from a well-characterized IBS-D cohort showed no substantial inflammation. Mesalazine has little effect on gene expression and its previous reported effect on fecal microbiota associated with much greater inflammation found in inflammatory bowel diseases is likely secondary to reduced inflammation. Increased expression of TLR4 and correlated receptors in IBS may mediate a general increase in sensitivity to external stimuli, particularly those that signal via the TLR system.

The Polyphosphate Kinase of Escherichia coli Is Required for Full Production of the Genotoxin Colibactin

Colibactin induces DNA damage in mammalian cells and has been linked to the virulence of Escherichia coli and the promotion of colorectal cancer (CRC). By looking for mutants attenuated in the promoter activity of clbB encoding one of the key enzymes for the production of colibactin, we found that a mutant of the gene coding for the polyphosphate kinase (PPK) produced less colibactin than the parental strain. We observed this phenotype in different strains ranging from pathogens responsible for meningitis, urinary tract infection, or mouse colon carcinogenesis to the probiotic Nissle 1917. We confirmed the role of PPK by using an inhibitor of PPK enzymatic activity, mesalamine (also known as 5-aminosalicylic acid). Interestingly, mesalamine has a local anti-inflammatory effect on the epithelial cells of the colon and is used to treat inflammatory bowel disease (IBD). Upon treatment with mesalamine, a decreased genotoxicity of colibactin-producing E. coli was observed both on epithelial cells and directly on purified DNA. This demonstrates the direct effect of mesalamine on bacteria independently from its anti-inflammatory effect on eukaryotic cells. Our results suggest that the mechanisms of action of mesalamine in treating IBD and preventing CRC could also lie in the inhibition of colibactin production. All in all, we demonstrate that PPK is required for the promoter activity of clbB and the production of colibactin, which suggests that PPK is a promising target for the development of anticolibactin and antivirulence strategies.IMPORTANCE Colibactin-producing E. coli induces DNA damage in eukaryotic cells and promotes tumor formation in mouse models of intestinal inflammation. Recent studies have provided strong evidence supporting the causative role of colibactin in human colorectal cancer (CRC) progression. Therefore, it is important to understand the regulation of the production of this genotoxin. Here, we demonstrate that polyphosphate kinase (PPK) is required for the promoter activity of clbB and the production of colibactin. Interestingly, PPK is a multifunctional player in bacterial virulence and stress responses and has been proposed as a new target for developing antimicrobial medicine. We observed inhibition of colibactin production by using a previously identified PPK inhibitor (i.e., mesalamine, an anti-inflammatory drug commonly prescribed for inflammatory bowel diseases). These data brought us a new perspective on the regulatory network of colibactin production and provided us a clue for the development of anticolibactin strategies for CRC treatment/prophylaxis.

Review article: how the intestinal microbiota may reflect disease activity and influence therapeutic outcome in inflammatory bowel disease

BACKGROUND

Intestinal bacteria produce metabolites and by-products necessary for homeostasis. Imbalance in this equilibrium is linked to multiple pathologies including inflammatory bowel disease (IBD). The role of the gut microbiota in determining treatment response is becoming apparent, and may act as biomarker for efficacy.

AIM

To describe knowledge about the intestinal microbiota on disease severity and treatment outcomes in IBD METHODS: Descriptive review using PubMed to identify literature on the intestinal microbiota in IBD RESULTS: Severe IBD has a less diverse microbiota with fewer commensal microbiota communities and more opportunistic pathogenic bacteria originating from the oral cavity or respiratory tract. IBD treatments can alter gut microbiota composition, but in vitro/in vivo studies are needed to prove causation. A diversification of the microbiota is observed during remission. Patients with a more diverse baseline microbiome and higher microbial diversity show better response to anti-tumour necrosis factor-α, vedolizumab and ustekinumab therapy. Higher abundance of short chain fatty acid-producing bacteria, fewer mucus-colonising bacteria and lower abundance of pro-inflammatory bacteria have also been associated with a favourable outcome. Predictive models, based on a combination of microbiota, clinical data and serological markers, have good accuracy for treatment outcome and disease severity.

CONCLUSION

The intestinal microbiota in IBD carries a set of promising biomarkers of disease activity and prediction of therapeutic outcome. Current insights may also help in designing microbiota modulation strategies to improve outcomes in IBD.

Gut Microbiome Changes in Patients with Active Left-Sided Ulcerative Colitis after Fecal Microbiome Transplantation and Topical 5-aminosalicylic Acid Therapy

Ulcerative colitis (UC) is an inflammatory bowel disease, and intestinal bacteria are implicated in the pathogenesis of this disorder. The administration of aminosalicylates (5-ASA) is a conventional treatment that targets the mucosa, while fecal microbial transplantation (FMT) is a novel treatment that directly targets the gut microbiota. The aim of this study was to identify changes in fecal bacterial composition after both types of treatments and evaluate clinical responses. Sixteen patients with active left-sided UC underwent enema treatment using 5-ASA (n = 8) or FMT (n = 8) with a stool from a single donor. Fecal microbiota were analyzed by 16S rDNA high-throughput sequencing, and clinical indices were used to assess the efficacy of treatments. 5-ASA therapy resulted in clinical remission in 50% (4/8) of patients, but no correlation with changes in fecal bacteria was observed. In FMT, remission was achieved in 37.5% (3/8) of patients and was associated with a significantly increased relative abundance of the families Lachnospiraceae, Ruminococcaceae, and Clostridiaceae of the phylum Firmicutes, and Bifidobacteriaceae and Coriobacteriaceae of the phylum Actinobacteria. At the genus level, Faecalibacterium, Blautia, Coriobacteria, Collinsela, Slackia, and Bifidobacterium were significantly more frequent in patients who reached clinical remission. However, the increased abundance of beneficial taxa was not a sufficient factor to achieve clinical improvement in all UC patients. Nevertheless, our preliminary results indicate that FMT as non-drug-using method is thought to be a promising treatment for UC patients.

Randomised clinical study: oral aspirin 325 mg daily vs placebo alters gut microbial composition and bacterial taxa associated with colorectal cancer risk

BACKGROUND

Aspirin is associated with decreased risk of colorectal cancer (CRC), potentially by modulating the gut microbiome.

AIMS

To evaluate the effect of aspirin on the gut microbiome in a double-blinded, randomised placebo-controlled pilot trial.

METHODS

Healthy volunteers aged 50-75 received a standard dose of aspirin (325 mg, N = 30) or placebo (N = 20) once daily for 6 weeks and provided stool samples every 3 weeks for 12 weeks. Serial measurements of gut microbial community composition and bacterial abundance were derived from 16S rRNA sequences. Linear discriminant analysis of effect size (LEfSe) was tested for between-arm differences in bacterial abundance. Mixed-effect regression with binomial distribution estimated the effect of aspirin use on changes in the relative abundance of individual bacterial taxa via an interaction term (treatment × time).

RESULTS

Over the study period, there were differences in microbial composition in the aspirin vs placebo arm. After treatment, four taxa were differentially abundant across arms: Prevotella, Veillonella, Clostridium XlVa and Clostridium XVIII clusters. Of pre-specified bacteria associated with CRC (n = 8) or aspirin intake (n = 4) in published studies, interactions were significant for four taxa, suggesting relative increases in Akkermansia, Prevotella and Ruminococcaceae and relative decreases in Parabacteroides, Bacteroides and Dorea in the aspirin vs placebo arm.

CONCLUSION

Compared to placebo, aspirin intake influenced several microbial taxa (Ruminococcaceae, Clostridium XlVa, Parabacteroides and Dorea) in a direction consistent with a priori hypothesis based on their association with CRC. This suggests that aspirin may influence CRC development through an effect on the gut microbiome. The findings need replication in a larger trial.

Interactions Between Food and Gut Microbiota: Impact on Human Health

Understanding the relationship between food and the gut microbiota, their interactions, and how each modulates the other is critical for successful promotion of human health. This review seeks to summarize ( a) the current knowledge on the effects of food and food components on gut microbiota and ( b) the association between gut microbiota, consumption of food, and food bioactive components and the resulting beneficial health outcomes. Our goal is to provide state-of-the-art information on food and gut microbiota interactions and to stimulate discussions and research approaches that will move the field forward.

Alteration of Fungal Microbiota After 5-ASA Treatment in UC Patients

The effect of treatment regimens on fungal microbiota is unclear in ulcerative colitis (UC) patients. Here, we aimed to clarify the effect of 5-aminosalicylic acid (5-ASA) treatment on gut fungal microbiota in UC patients. Fifty-seven UC patients, including 20 treatment-naïve and 37 5-ASA-treated, were recruited into an exploration study. We compared the gut fungal profiles of these 2 groups of patients using ITS1-2 rDNA sequencing. Ten out of 20 treatment-naïve UC patients were followed up and enrolled for a validation study and underwent a 5-ASA treatment. We assessed the longitudinal differences of fungal microbiota in these patients before and after 5-ASA treatment. Results acquired from the validation study were accordant to those from the exploration study. Ascomycota was the dominant phylum in both noninflamed and inflamed mucosae. At the phylum level, Ascomycota decreased in inflamed mucosae before 5-ASA treatment. At the genus level, pathogens such as Scytalidium, Morchella, and Paecilomyces increased, and Humicola and Wickerhamomyces decreased in inflamed mucosae. After 5-ASA treatment, Ascomycota and Wickerhamomyces increased and Scytalidium, Fusarium, Morchella, and Paecilomyces decreased in both noninflamed and inflamed mucosae. Additionally, the balanced bacteria-fungi correlation was interrupted in inflamed mucosae, and 5-ASA treatment altered group-specific fungal microbiota and restored bacteria-fungi correlation in UC patients. Our results demonstrated that fungal diversity and composition were altered and the bacteria-fungi correlation was restored in inflamed mucosae after 5-ASA treatment.

5-Aminosalicylic acid for treatment of irritable bowel syndrome: A protocol for a systematic review and meta-analysis

BACKGROUND

The global prevalence of irritable bowel syndrome (IBS) is estimated to be as high as 15%, and it is estimated that IBS has a prevalence of approximately 10% to 20% in Western countries. Some trials showed mesalazine (5-aminosalicylic acid [5-ASA]) might be effective for IBS, but the results still need to be confirmed. Hence, this meta-analysis is designed to assess the efficacy and safety of mesalazine for IBS in adults and children.

METHODS

We conducted a comprehensive database search for randomized trials of mesalazine for IBS in PubMed, EMBASE, and the Cochrane Library. The search strategy was performed from inception to December 31, 2019, without restrictions on publication status and language. The reference lists of the included articles were also checked to identify additional studies for potential inclusion. Two reviewers will independently review all literature for inclusion and assess their risk of bias. Two reviewers will independently extract data from eligible studies based on a pre-designed standardized form. Any disagreements will be resolved by consensus. Stata SE 15.0 software will be used for data synthesis.

RESULTS

This is the first meta-analysis focusing on mesalazine for the treatment of IBS. We predict it will provide high-quality synthesis on existing evidence for IBS and a relatively comprehensive reference for clinical practice and development of clinical guidelines for IBS.

CONCLUSION

This protocol outlined the significance and methodological details of a systematic review of mesalazine for IBS. This ongoing meta-analysis will provide high-quality synthesis on existing evidence for IBS.

REGISTRATION

The meta-analysis has been prospectively registered in PROSPERO (CRD42019147860).

Distinct patterns of short-chain fatty acids during flare in patients with ulcerative colitis under treatment with mesalamine or a herbal combination of myrrh, chamomile flowers, and coffee charcoal: secondary analysis of a randomized controlled trial

OBJECTIVES

Short-chain fatty acids are involved in the regulation of the gut immune system. In ulcerative colitis, short-chain fatty acids are often reduced, especially during flare. This study evaluated exploratively the pattern of butyrate and total short-chain fatty acids in patients with ulcerative colitis during flare treated either with mesalamine or a herbal preparation consisting of myrrh, chamomile flowers, and coffee charcoal which showed promising results in maintaining remission in a randomized double-blind, double-dummy, controlled clinical trial (EudraCT-Number 2007-007928-18).

METHODS

Patients were treated with the herbal preparation or mesalamine. Clinical activity was monitored by Clinical Colitis Activity Index. Using gas chromatography, we analyzed fecal samples of 38 patients who experienced a flare during treatment.

RESULTS

Paired t-test showed a significant decline of total short-chain fatty acids [M before = 66.12, SD = 39.59; M after = 29.83, SD = 15.05; 95% bootstrap confidence interval (20.53-55.30); P = 0.01) and of butyrate [M before 11.35, SD = 7.56; M after = 6.50, SD = 3.55; 95% bootstrap confidence interval (2.06-8.11); P = 0.02] in the event of a flare for patients treated with mesalamine but not for patients treated with the herbal preparation.

CONCLUSION

Patients who received the herbal preparation did not show a significant decline of total short-chain fatty acids in the event of a flare. Since a decline of short-chain fatty acids might lead to unfavorable health impairments, a combination of the two treatments should be further investigated.

Distinct Microbial Populations Exist in the Mucosa-associated Microbiota of Diarrhea Predominant Irritable Bowel Syndrome and Ulcerative Colitis

GOALS

The goal of this study was to observe the bacterial colonization in the intestinal mucosa in the patients with diarrhea predominant irritable bowel syndrome (IBS-D) and ulcerative colitis (UC), and compare the mucosa-associated microbiota among the IBS-D patients, UC patients and the healthy control, and explore the correlation of the mucosa-associated microbiota with clinical manifestations.

STUDY

A total of 20 IBS-D patients, 28 patients with UC (16 active, 12 inactive) and 16 healthy subjects were enrolled in the study. They all underwent colonoscopies in the Gastrointestinal Endoscopy Center in the Second Affiliated Hospital of Xi'an Jiaotong University from June 2016 to October 2016. The mucosa specimens were taken at the junction of rectum and sigmoid colon for fluorescent in situ hybridization (FISH). Then the observed mucosa-associated microbiota was counted and compared.

RESULTS

(1) In the IBS-D patients, the mucosa-associated bacteria were found to colonize in the surface of mucosa and the adjacent mucin layer. And in active UC, Escherichia coli, and Bacteroides were found in the lamina propria, in addition to bacterial colonization in the above-mentioned areas. (2) The total count of mucosa-associated bacteria and the individual counts of E. coli, Clostridium, and Bacteroides were significantly increased, and Bifidobacteria significantly decreased (P<0.05) in the IBS-D patients and UC patients. Counts of Lactobacillus were decreased only in UC patients compared with the healthy control. And a significantly larger variation of the above-mentioned bacterial counts was found in the patients with UC, particularly in those with active UC, compared with those with IBS-D (P<0.05); the counts in the UC group were 1.3 to 5.3 times more or less than those in the IBS-D group. (3) Compared with healthy controls and IBS-D, the total count of bacteria and the individual counts of E. coli and Bacteroides in the lamina propria in active UC were significantly increased (P<0.05). (4) A significant negative correlation of the counts of Lactobacillus and Bifidobacteria with the defecation frequency and fecal characteristics (P<0.05) was found in the IBS-D patients; in those with UC, both the total count of bacteria and the individual counts of E. coli, Clostridium, Bacteroides, Lactobacillus, and Bifidobacteria were significantly correlated, positively or negatively, with the related clinical manifestations and the activity of the disease (P<0.05).

CONCLUSIONS

Compared with the healthy control, intestinal microecology was changed most obviously in UC with much smaller differences though in the same direction in IBS-D. The translocation of some bacteria into the lamina propria was found in UC, particularly in active UC. The changes of mucosa-associated microbiota were related more or less to some clinical manifestations in IBS-D and UC.

Bacterial biofilms in human gastrointestinal tract: An intricate balance between health and inflammatory bowel diseases

Inflammatory bowel disease (IBD) has been a worldwide health problem. It is characterized by severe intestinal inflammation due to immune responses against the gut microbes in genetically susceptible individuals. The understanding of gut microbiota for its composition and complex interaction in normal and diseased conditions has been assisted by the use of molecular, metagenomics and meta transcriptomics studies. The alteration of intestinal microbiota is the key determinant in the degree of inflammation caused and the prolonged course of disease. The relationship between luminal gut bacteria and innate immunity is also of prime significance. Such developments have further led to the search of specific (including bacteria and fungi) as a causative agent of IBD. Although detailed research has been done for the role of gut microbiota in IBD, molecular mechanisms and related gene expression are still not well understood in this disease, which hampers the generation of effective therapeutic agents for IBD. This paper assessed various factors contributing to IBD, genetic dysbiosis and pathogenic influence in the gut microbiota, interactions such as microbiome-host immune system interaction and microbe-microbe interactions involved in IBD, currently available IBD therapies, followed by a detailed review on bacterial infections that might be involved in IBD, globally and specifically in India.

Association of Parkinson's disease and treatment with aminosalicylates in inflammatory bowel disease: a cross-sectional study in a Spain drug dispensation records

OBJECTIVES

To analyse the association between aminosalicylate-treated inflammatory bowel disease (IBD) and Parkinson's disease (PD) at population level.

DESIGN

Cross-sectional study.

SETTING

The study was performed based on electronic drug prescription and dispensation records of the Andalusian Public Health System.

PARTICIPANTS

All individuals aged ≥50 years with at least one drug dispensation during December 2014 were identified from the records.

PRIMARY AND SECONDARY OUTCOME MEASURES

Groups were formed: 'possible PD' group, including all who received an anti-Parkinson agent; 'possible IBD' group, those treated with mesalazine and/or derivatives (5-aminosalicylic acid (5-ASA)); and 'possible PD and IBD', including those receiving both anti-Parkinson agent and 5-ASA. Prevalence of possible PD was determined among those with possible IBD and among those without this condition. The age-adjusted and sex-adjusted OR was calculated.

RESULTS

We recorded 2 020 868 individuals (68±11 years, 56% female), 19 966 were included in possible PD group (75±9 years, 53% female) and 7485 in possible IBD group (64±10 years, 47% female); only 56 were included in both groups (76±8 years, 32% female). The prevalence of possible PD was 0.7% among those with possible IBD and 1% among those without this condition (adjusted OR=0.94; 95% CI 0.72 to 1.23; p=0.657). OR was 0.28 in individuals aged ≤65 years (95% CI 0.10 to 0.74; p=0.01) and 1.17 in older individuals (95% CI 0.89 to 1.54; p=0.257).

CONCLUSIONS

Within the limitations of this study, the results suggest a protective role for IBD and/or 5-ASA against PD development, especially among under 65-year olds. Further studies are warranted to explore this association given its scientific and therapeutic implications.

Mucosal 5-aminosalicylic acid concentration, drug formulation and mucosal microbiome in patients with quiescent ulcerative colitis

BACKGROUND

5-aminosalicylic acid (5-ASA) is the first-line therapy for ulcerative colitis (UC). 5-ASA acts locally in the colonic mucosa by numerous proposed mechanisms, and is metabolised by N-acetyltransferase (NAT). Large variations in mucosal 5-ASA concentrations have been reported, but the underlying mechanisms are not understood.

AIM

To study the relationship between 5-ASA concentration, 5-ASA formulation, NAT genotype and bacterial microbiome in patients with UC.

METHODS

Patients with quiescent UC, using monotherapy of Mezavant (n = 18), Asacol (n = 14) or Pentasa (n = 10), 4.0-4.8 g/day were included. 5-ASA was measured in colonic mucosal biopsies and serum by ultra-high performance liquid chromatography. NAT genotypes were determined by Sanger sequencing. Bacterial microbiome was sequenced from faeces and mucosa by 16S rRNA sequencing using Illumina Miseq.

RESULTS

Mezavant provided the highest mucosal 5-ASA levels (geometric mean 2.39 ng/mg), followed by Asacol (1.60 ng/mg, 33% lower, P = 0.50) and Pentasa (0.57 ng/mg, 76% lower, P = 0.033). Mucosal 5-ASA concentration was not associated with NAT genotype, but serum 5-ASA concentration and NAT1 genotype was associated (P = 0.044). Mucosal 5-ASA concentration was positively associated with mucosal bacterial diversity (P = 0.0005) and bacterial composition. High mucosal 5-ASA concentration was related to reduced abundance of pathogenic bacteria such as Proteobacteria, and increased abundance of several favourable bacteria such as Faecalibacterium.

CONCLUSIONS

Mucosal 5-ASA concentration is positively associated with bacterial diversity and a mucosal bacterial composition that are perceived favourable in UC. Mezavant yielded higher mucosal 5-ASA concentrations than Pentasa. 5-ASA may have beneficial effects on the mucosal microbiome, and high concentrations possibly amend dysbiosis in UC.

Clostridium difficile infection in patients with inflammatory bowel disease: a case control study

OBJECTIVE

Characterization of predisposing factors for Clostridium difficile infection recurrence (rCDI) and outcome in inflammatory bowel disease (IBD) patients.

METHODS

Clinical characteristics of 167 inflammatory bowel disease patients with Clostridium difficile infection (IBD-CDI cohort) treated in Helsinki University Central Hospital were gathered. Medical history of the last three months preceding a toxin positive CDI test was recorded. Parameters, including ribotype of C. difficile, mortality and recurrence were compared with age and gender-matched C. difficile patients (CDI cohort).

RESULTS

No difference was found in rCDI between IBD-CDI and CDI cohorts. As compared with IBD subtypes, rCDI was least common among patients with Crohn's disease. The use of immunosuppressant therapy was higher in IBD patients with two or more CDI episodes. C. difficile ribotype 027 increased the rates for rCDI in IBD patients but not in non-IBD-CDI patients. The prevalence of 027 ribotype and mortality rates did not differ significantly among the cohorts. None of the IBD patients underwent colectomy upon CDI.

CONCLUSION

IBD patients are not more susceptible for rCDI than non-IBD patients. Predisposing factors for rCDI among IBD patients are associated with immunosuppressant treatments, colon affecting IBD and CDI caused by ribotype 027. CDI does not worsen the prognosis of IBD patients.

The Effect of Vitamin D on Intestinal Inflammation and Faecal Microbiota in Patients with Ulcerative Colitis

BACKGROUND AND AIMS

Vitamin D may be immunomodulatory and alter faecal microbiota, but results from clinical studies in humans to date have been inconclusive. This study aimed to assess the effect of vitamin D replacement in vitamin D-deficient patients with and without ulcerative colitis [UC] on inflammation and faecal microbiota.

METHODS

Vitamin D was replaced over 8 weeks in patients with active UC [defined by faecal calprotectin ≥ 100 µg/g], inactive UC [faecal calprotectin < 100 µg/g] and non-inflammatory bowel disease [IBD] controls with baseline serum 25[OH] vitamin D <50 nmol/l, and markers of inflammation and faecal microbiota were analysed.

RESULTS

Eight patients with active UC, nine with inactive UC and eight non-IBD controls received 40000 units cholecalciferol weekly for 8 weeks. Mean baseline 25[OH] vitamin D increased from 34 [range 12-49] to 111 [71-158] nmol/l [p < 0.001], with no difference across the groups [p = 0.32]. In patients with active UC, faecal calprotectin levels decreased from a median 275 to 111 µg/g [p = 0.02], platelet count decreased [mean 375 to 313 × 109/l, p = 0.03] and albumin increased [mean 43 to 45 g/l, p = 0.04]. These parameters did not change in patients with inactive UC or non-IBD controls. No changes in overall faecal bacterial diversity were noted although a significant increase in Enterobacteriaceae abundance was observed in patients with UC [p = 0.03].

CONCLUSIONS

Vitamin D supplementation was associated with reduced intestinal inflammation in patients with active UC, with a concomitant increase in Enterobacteriaceae but no change in overall faecal microbial diversity.

Effects of medicines used to treat gastrointestinal diseases on the pharmacokinetics of coadministered drugs: a PEARRL Review

Objectives

Drugs used to treat gastrointestinal diseases (GI drugs) are widely used either as prescription or over-the-counter (OTC) medications and belong to both the 10 most prescribed and 10 most sold OTC medications worldwide. The objective of this review article is to discuss the most frequent interactions between GI and other drugs, including identification of the mechanisms behind these interactions, where possible.

Key findings

Current clinical practice shows that in many cases, these drugs are administered concomitantly with other drug products. Due to their metabolic properties and mechanisms of action, the drugs used to treat gastrointestinal diseases can change the pharmacokinetics of some coadministered drugs. In certain cases, these interactions can lead to failure of treatment or to the occurrence of serious adverse events. The mechanism of interaction depends highly on drug properties and differs among therapeutic categories. Understanding these interactions is essential to providing recommendations for optimal drug therapy.

Summary

Interactions with GI drugs are numerous and can be highly significant clinically in some cases. While alterations in bioavailability due to changes in solubility, dissolution rate, GI transit and metabolic interactions can be (for the most part) easily identified, interactions that are mediated through other mechanisms, such as permeability or microbiota, are less well-understood. Future work should focus on characterising these aspects.

The evidence for fungus in Crohn's disease pathogenesis

Current evidence suggests the etiology of inflammatory bowel diseases (IBD) involves the confluence of host genetic, environmental, and microbial factors that lead to chronic, and often refractory, disease in susceptible individuals. The involvement of microbial triggers in IBD, including Crohn's disease (CD), is increasingly evident with supporting data provided with advancements in metagenomic sequencing that have identified perturbations in microbial structure and function-broadly termed dysbiosis-in CD patients compared with healthy subjects. This concept is supported by the finding germ-free animals with CD genetic susceptibility fail to develop disease; demonstrating microorganisms are necessary but not sufficient for CD. The vast majority of CD microbiome research has focused on the complex bacterial communities and microbiome dysbiosis in the gut with 16S metagenomic sequencing. However, emerging data capturing eukaryotes suggest fungal opportunistic pathogens are also associated with IBD pathogenesis and chronicity. This hypothesis is further supported by historical observations that CD patient populations display elevated antibodies against fungal targets, even evident before disease diagnosis. This review discusses the current findings in the field, followed by historical and metagenomic evidence for fungal pathogens in the development and recurrence of CD in adult and pediatric populations.

Iron Sequestration in Microbiota Biofilms As A Novel Strategy for Treating Inflammatory Bowel Disease

Significant alterations of intestinal microbiota and anemia are hallmarks of inflammatory bowel disease (IBD). It is widely accepted that iron is a key nutrient for pathogenic bacteria, but little is known about its impact on microbiota associated with IBD. We used a model device to grow human mucosa-associated microbiota in its physiological anaerobic biofilm phenotype. Compared to microbiota from healthy donors, microbiota from IBD patients generate biofilms ex vivo that were larger in size and cell numbers, contained higher intracellular iron concentrations, and exhibited heightened virulence in a model of human intestinal epithelia in vitro and in the nematode Caenorhabditis elegans. We also describe an unexpected iron-scavenging property for an experimental hydrogen sulfide-releasing derivative of mesalamine. The findings demonstrate that this new drug reduces the virulence of IBD microbiota biofilms through a direct reduction of microbial iron intake and without affecting bacteria survival or species composition within the microbiota. Metabolomic analyses indicate that this drug reduces the intake of purine nucleosides (guanosine), increases the secretion of metabolite markers of purine catabolism (urate and hypoxanthine), and reduces the secretion of uracil (a pyrimidine nucleobase) in complex multispecies human biofilms. These findings demonstrate a new pathogenic mechanism for dysbiotic microbiota in IBD and characterize a novel mode of action for a class of mesalamine derivatives. Together, these observations pave the way towards a new therapeutic strategy for treatment of patients with IBD.

5-Aminosalicylic Acid Alters the Gut Bacterial Microbiota in Patients With Ulcerative Colitis

Background: The aim of this study was to clarify the effect of 5-aminosalicylic acid (5-ASA) treatment on gut bacterial microbiota in patients with ulcerative colitis (UC).

Methods: A total of 57 UC patients, including 20 untreated and 37 5-ASA-treated, were recruited into an exploration cohort. We endoscopically collected both non-inflamed and inflamed mucosal samples from all patients, and compared the gut bacterial profiles using 16S rDNA sequencing. Ten untreated UC patients were then treated with 5-ASA and subsequently recruited for an independent validation study to confirm the acquired data.

Results: In untreated UC patients, compared with those in non-inflamed mucosae, Firmicutes (such as Enterococcus) were decreased and Proteobacteria (e.g., Escherichia–Shigella) were increased in the inflamed mucosae. Compared with the inflamed mucosae of untreated UC patients, there was a higher abundance of Firmicutes (e.g., Enterococcus) and lower Proteobacteria (Escherichia–Shigella) in the inflamed mucosae of 5-ASA treated UC patients. In the validation cohort, after administration of 5-ASA, bacterial alteration was consistent with these data. Furthermore, there was a skewed negative correlation between Escherichia–Shigella and bacterial genera of Firmicutes in the inflamed mucosae. 5-ASA treatment decreased the strength of bacterial correlation and weakened the skewed negative correlation pattern.

Conclusion: The microbial dysbiosis (mainly characterized by an increased abundance in the Escherichia–Shigella genus) and the skewed negative correlation between Escherichia–Shigella and bacterial genera of Firmicutes are two characteristics of the inflamed mucosae of UC patients. 5-ASA treatment decreases Escherichia–Shigella and weakens the skewed correlations, which may be related to its treatment efficiency.

Treatment of diverticular disease: an update on latest evidence and clinical implications

BACKGROUND

Diverticular disease (DD) is a common condition, especially in Western countries. In about 80% of patients, colonic diverticula remain asymptomatic (diverticulosis), while approximately 20% of patients may develop abdominal symptoms (symptomatic uncomplicated diverticular disease, SUDD) and, eventually complications as acute diverticulitis (AD). The management of this condition has been improved, and in the last five years European countries and the USA have published guidelines and recommendations.

SCOPE

To summarize the latest evidence and clinical implication in treatment of DD focusing the attention either on the treatment of diverticulosis, SUDD and AD together with the primary and secondary prevention of diverticulitis.

FINDINGS

The present review was based on the latest evidence in the treatment of DD in the last 10 years. In the last 5 years, six countries issued guidelines on DD with differences regarding covered topics and recommendations regarding treatments. At present there is a lack of rationale for drug use in patients with asymptomatic diverticulosis, but there are limited indications to suggest an increase in dietary fibre to reduce risk of DD. To achieve symptomatic relief in SUDD patients, several therapeutic strategies with fibre, probiotics, rifaximin and mesalazine have been proposed even if a standard therapeutic approach remained to be defined. Agreement has been reached for the management of AD, since recent guidelines showed that antibiotics can be used selectively, rather than routinely in uncomplicated AD, although use of antibiotics remained crucial in the management of complicated cases. With regard to treatment for the primary and secondary prevention of AD, the efficacy of rifaximin and mesalazine has been proposed although with discordant recommendations among guidelines.

CONCLUSION

Treatment of DD represented an important challenge in clinical practice, especially concerning management of SUDD and the primary and secondary prevention of AD.

Gut microbiota in the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a chronic and relapsing inflammatory disorder of the intestine. Although its incidence is increasing globally, the precise etiology remains unclear and a cure for IBD has yet to be discovered. The most accepted hypothesis of IBD pathogenesis is that complex interactions between genetics, environmental factors, and the host immune system lead to aberrant immune responses and chronic intestinal inflammation. The human gut harbors a complex and abundant aggregation of microbes, collectively referred to as the gut microbiota. The gut microbiota has physiological functions associated with nutrition, the immune system, and defense of the host. Recent advances in next-generation sequencing technology have identified alteration of the composition and function of the gut microbiota, which is referred to as dysbiosis, in IBD. Clinical and experimental data suggest dysbiosis may play a pivotal role in the pathogenesis of IBD. This review is focused on the physiological function of the gut microbiota and the association between the gut microbiota and pathogenesis in IBD. In addition, we review the therapeutic options for manipulating the altered gut microbiota, such as probiotics and fecal microbiota transplantation.

Pharmacological Efficacy/Toxicity of Drugs: A Comprehensive Update About the Dynamic Interplay of Microbes

Oral ingestion is a common, easy to access, route for therapeutic drugs to be delivered. The conception of the gastrointestinal tract as a passive physiological compartment has evolved toward a dynamic perspective of the same. Thus, microbiota plays an important role in contributing with additional metabolic capacities to its host as well as to its phenotypic heterogeneity. These adaptations in turn influence the efficacy and toxicity of a broad range of drugs. Notwithstanding, xenobiotics and therapeutic drugs affecting the microbiome's activity also significantly impact metabolism affecting different organs and tissues, and thereby drugs' toxicity/efficacy effects. Other physiological interfaces (i.e., gut, lungs, and skin) also represent complex media with features about microbiota's composition. In addition, there have been described key regulatory effects of microbes on immunotherapy, because of its potential harnessing the host immune system, mental disorders by modulating neuroendocrine systems and cancer. These alterations are responsible of physiological variations in the response(s) between individuals and populations. However, the study of population-based differences in intestinal microbial-related drug metabolism has been largely inferential. This review outlines major reciprocal implications between drugs and microbes regulatory capacities in pharmacotherapy.

Post-Infectious Irritable Bowel Syndrome

PURPOSE OF REVIEW

Post-infectious irritable bowel syndrome (PI-IBS) is characterized by persistent abdominal pain and diarrhea, typically following an episode of infectious gastroenteritis. The mechanisms that underlie IBS-D remain elusive, but PI-IBS provides a mechanistic model of this disorder. This review provides an up-to-date appraisal of the pathophysiology, clinical features, and management approaches for PI-IBS.

RECENT FINDINGS

Disordered immune reactions and release of cytokines with resultant gut inflammation and dysfunction appear to be key features of PI-IBS. Disordered brain-gut-microbiota interactions, type of infecting agent, and host-genetic susceptibility are risk factors but also are reasons for the varying spectrum of clinical severity. Although prognosis is generally good, symptoms and inflammation may persist for a long time. Symptomatic relief with antidiarrheals, antispasmodics, 5HT₃ antagonists, mesalamine, probiotics, and low-dose antidepressants remain the primary approaches, but in some difficult cases, a combination of drugs that target the pathophysiology may be helpful. PI-IBS has many overlapping features with IBS-D and shares similar pathophysiology and management approaches.

Systematic review with meta-analysis: rifaximin is effective and safe for the treatment of small intestine bacterial overgrowth

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is a heterogeneous syndrome, characterised by an increased number and/or abnormal type of bacteria in the small bowel. Over the past decades, rifaximin has gained popularity for this indication despite its use is not evidence based.

AIM

To perform a systematic review and meta-analysis to summarise evidence about the efficacy and safety of rifaximin to eradicate SIBO in adult patients.

METHODS

MEDLINE, EMBASE, CCRCT, Scopus and Web of Science were searched from inception to March 16, 2015 for RCTs and observational studies. Furthermore, abstract books of major European, American and Asian gastroenterological meetings were also examined.

RESULTS

Thirty-two studies involving 1331 patients were included. The overall eradication rate according to intention-to-treat analysis was 70.8% (95% CI: 61.4-78.2; I² = 89.4%) and to per protocol analysis 72.9% (95% CI: 65.5-79.8; I² = 87.5%). Meta-regression identified three covariates (drug dose, study design and co-therapy) independently associated with an increased eradication rate. The overall rate of adverse events was 4.6% (95% CI: 2.3-7.5; I² = 63.6%). In the subset of studies (n= 10) allowing the analysis, improvement or resolution of symptoms in patients with eradicated SIBO was found to be 67.7% (95% CI: 44.7-86.9; I² = 91.3%).

CONCLUSIONS

Rifaximin treatment seems to be effective and safe for the treatment of SIBO. However, the quality of the available studies is generally poor. Well-designed RCTs are needed to substantiate these findings and to establish the optimal regimen.

Pharmacological Approach for Managing Pain in Irritable Bowel Syndrome: A Review Article

Context

Visceral pain is a leading symptom for patients with irritable bowel syndrome (IBS) that affects 10% - 20 % of the world population. Conventional pharmacological treatments to manage IBS-related visceral pain is unsatisfactory. Recently, medications have emerged to treat IBS patients by targeting the gastrointestinal (GI) tract and peripheral nerves to alleviate visceral pain while avoiding adverse effects on the central nervous system (CNS). Several investigational drugs for IBS also target the periphery with minimal CNS effects.

Evidence of Acquisition

In this paper, reputable internet databases from 1960 - 2016 were searched including Pubmed and ClinicalTrials.org, and 97 original articles analyzed. Search was performed based on the following keywords and combinations: irritable bowel syndrome, clinical trial, pain, visceral pain, narcotics, opioid, chloride channel, neuropathy, primary afferent, intestine, microbiota, gut barrier, inflammation, diarrhea, constipation, serotonin, visceral hypersensitivity, nociceptor, sensitization, hyperalgesia.

Results

Certain conventional pain managing drugs do not effectively improve IBS symptoms, including NSAIDs, acetaminophen, aspirin, and various narcotics. Anxiolytic and antidepressant drugs (Benzodiazepines, TCAs, SSRI and SNRI) can attenuate pain in IBS patients with relevant comorbidities. Clonidine, gabapentin and pregabalin can moderately improve IBS symptoms. Lubiprostone relieves constipation predominant IBS (IBS-C) while loperamide improves diarrhea predominant IBS (IBS-D). Alosetron, granisetron and ondansetron can generally treat pain in IBS-D patients, of which alosetron needs to be used with caution due to cardiovascular toxicity. The optimal drugs for managing pain in IBS-D and IBS-C appear to be eluxadoline and linaclotide, respectively, both of which target peripheral GI tract.

Conclusions

Conventional pain managing drugs are in general not suitable for treating IBS pain. Medications that target the GI tract and peripheral nerves have better therapeutic profiles by limiting adverse CNS effects.

The anti-inflammatory drug mesalamine targets bacterial polyphosphate accumulation

Mesalamine serves as the gold standard in treating ulcerative colitis. However, its precise mechanism(s) of action remains unclear. Here, we show that mesalamine treatment rapidly decreases polyphosphate levels in diverse bacteria, including members of the human gut microbiome. This decrease sensitizes bacteria towards oxidative stress, reduces colonization and attenuates persister cell and biofilm formation, suggesting that mesalamine aids in diminishing the capacity of bacteria to persist within chronically inflamed environments.

The fecal microbiota as a biomarker for disease activity in Crohn's disease

Monitoring mucosal inflammation is crucial to prevent complications and disease progression in Crohn's disease (CD). Endoscopy is the current standard, but is invasive. Clinical activity scores and non-invasive biochemical markers do not correlate well with mucosal inflammation. Microbial perturbations have been associated with disease activity in CD. Therefore, we aimed to investigate its potential use to differentiate CD patients in remission from those with an exacerbation. From 71 CD patients repeated fecal samples were collected, resulting in 97 active disease and 97 remission samples based on a combination of biochemical and clinical parameters. The microbiota composition was assessed by pyrosequencing of the 16S rRNA V1-V3 region. Random Forest analysis was used to find the most discriminatory panel of operational taxonomic units (OTUs) between active and remission samples. An independent internal validation set was used to validate the model. A combination of 50 OTUs was able to correctly predict 73% of remission and 79% of active samples with an AUC of 0.82 (sensitivity: 0.79, specificity: 0.73). This study demonstrates that fecal microbial profiles can be used to differentiate between active and remission CD and underline the potential of the fecal microbiota as a non-invasive tool to monitor disease activity in CD.

Treatment of Diverticular Disease With Aminosalicylates: The Evidence

Colonic diverticulosis is an increasingly common condition in Western industrialized countries. About 20% of patients develop symptoms, including abdominal pain, bloating, changes in bowel habits, and, eventually, diverticulitis or other complications. The management of symptomatic uncomplicated diverticular disease (SUDD) and the prevention of acute diverticulitis remains a challenge for the clinician. The rationale for the use of aminosalicylates, such as mesalazine, is based on the assumption of low-grade inflammation in SUDD and symptoms generation, whereas an overt inflammation may induce diverticulitis in patients with diverticular disease. Clinical scenarios in which the efficacy and safety of mesalazine have been studied include SUDD, prevention of diverticulitis, and of recurrent diverticulitis. Data from uncontrolled studies suggest a benefit of mesalazine on patients with SUDD, whereas data from randomized controlled trials showed some evidence of improvement of symptoms, although contrasting results are reported. The largest study so far published on the efficacy of mesalamine in the prevention of recurrence of diverticulitis showed that mesalamine was not superior to placebo. At this time, the role of mesalazine in the prevention of acute diverticulitis remains to be defined with many issues open and unresolved.

The intestinal microbiome, barrier function, and immune system in inflammatory bowel disease: a tripartite pathophysiological circuit with implications for new therapeutic directions

We discuss the tripartite pathophysiological circuit of inflammatory bowel disease (IBD), involving the intestinal microbiota, barrier function, and immune system. Dysfunction in each of these physiological components (dysbiosis, leaky gut, and inflammation) contributes in a mutually interdependent manner to IBD onset and exacerbation. Genetic and environmental risk factors lead to disruption of gut homeostasis: genetic risks predominantly affect the immune system, environmental risks predominantly affect the microbiota, and both affect barrier function. Multiple genetic and environmental 'hits' are likely necessary to establish and exacerbate disease. Most conventional IBD therapies currently target only one component of the pathophysiological circuit, inflammation; however, many patients with IBD do not respond to immune-modulating therapies. Hope lies in new classes of therapies that target the microbiota and barrier function.

Pharmacological, Pharmacokinetic, and Pharmacogenomic Aspects of Functional Gastrointestinal Disorders

This article reviews medications commonly used for the treatment of patients with functional gastrointestinal disorders. Specifically, we review the animal models that have been validated for the study of drug effects on sensation and motility; the preclinical pharmacology, pharmacokinetics, and toxicology usually required for introduction of new drugs; the biomarkers that are validated for studies of sensation and motility endpoints with experimental medications in humans; the pharmacogenomics applied to these medications and their relevance to the FGIDs; and the pharmacology of agents that are applied or have potential for the treatment of FGIDs, including psychopharmacologic drugs.

Post-infectious irritable bowel syndrome (PI-IBS) after infection with Shiga-like toxin-producing Escherichia coli (STEC) O104:H4: A cohort study with prospective follow-up

BACKGROUND

In May/June 2011, the new Shiga-like toxin-producing Escherichia coli (STEC) strain O104:H4 caused the severest outbreak ever recorded of hemorrhagic enterocolitis in 3842 patients in Germany.

OBJECTIVES

As bacterial enterocolitis is an established risk factor of subsequent irritable bowel syndrome (IBS), we aimed to estimate prevalence and incidence of post-infectious (PI)-IBS after six and 12 months in a cohort of STEC O104:H4 patients and to prospectively identify associated somatic and psychometric risk factors.

METHODS

A total of 389 patients were studied prospectively at baseline and at six and 12 months after STEC infection using STEC disease-related questionnaires and validated instruments for IBS (Rome III) and psychological factors. Frequencies and logistic regression models using multiple imputations were applied to assess predictor variables.

RESULTS

Prevalence of IBS increased from 9.8% prior to STEC infection to 23.6% at six and 25.3% at 12 months after STEC infection. In patients without IBS symptoms prior to STEC infection, incidence of new IBS was 16.9%. Logistic regression models indicated higher somatization and anxiety scores as risk factors for, and mesalazine treatment during, STEC infection as the only significant protective factor against IBS. No other factor analyzed, including disease severity, showed an association.

CONCLUSIONS

PI-IBS rates following this unusually severe STEC outbreak were similar to what has been observed after other infectious gastroenteritis outbreaks. Our findings suggest that mesalazine may have reduced the risk of subsequent PI-IBS. As altered mucosal immune activity is a pivotal pathogenic factor in PI-IBS, our observation of a potential protective effect of mesalazine might be explained by its known modulatory action on mucosal immunity, and may warrant further investigation.

Mechanisms of Microbe-Host Interaction in Crohn's Disease: Dysbiosis vs. Pathobiont Selection

Crohn’s disease (CD) is a systemic chronic inflammatory condition mainly characterized by discontinuous transmural pathology of the gastrointestinal tract and frequent extraintestinal manifestations with intermittent episodes of remission and relapse. Genome-wide association studies identified a number of risk loci that, catalyzed by environmental triggers, result in the loss of tolerance toward commensal bacteria based on dysregulated innate effector functions and antimicrobial defense, leading to exacerbated adaptive immune responses responsible for chronic immune-mediated tissue damage. In this review, we discuss the inter-related role of changes in the intestinal microbiota, epithelial barrier integrity, and immune cell functions on the pathogenesis of CD, describing the current approaches available to investigate the molecular mechanisms underlying the disease. Substantial effort has been dedicated to define disease-associated changes in the intestinal microbiota (dysbiosis) and to link pathobionts to the etiology of inflammatory bowel diseases. A cogent definition of dysbiosis is lacking, as well as an agreement of whether pathobionts or complex shifts in the microbiota trigger inflammation in the host. Among the rarely available animal models, SAMP/Yit and TNF^deltaARE mice are the best known displaying a transmural CD-like phenotype. New hypothesis-driven mouse models, e.g., epithelial-specific Caspase8^−/−, ATG16L1^−/−, and XBP1^−/− mice, validate pathway-focused function of specific CD-associated risk genes highlighting the role of Paneth cells in antimicrobial defense. To study the causal role of bacteria in initiating inflammation in the host, the use of germ-free mouse models is indispensable. Unraveling the interactions of genes, immune cells and microbes constitute a criterion for the development of safe, reliable, and effective treatment options for CD.

Meta-analysis of mesalazine for irritable bowel syndrome

AIM: To evaluate the efficacy and safety of mesalazine for irritable bowel syndrome.

METHODS: Online databases, including China National Knowledge Infrastructure database (CNKI), VIP database, Wanfang database, PubMed, MEDLINE and Cochrane Library, were searched for randomized controlled trials of mesalazine for irritable bowel syndrome. After assessing the methodological strength, we extracted relevant data from the included studies to conduct a meta-analysis.

RESULTS: Based on the inclusion and exclusion criteria, 13 randomized controlled trails with a total of 1349 patients were included in this study. Clinical remission rate and abdominal pain score were significantly improved in the mesalazine group when compared with the control group. However, there was no significant difference in adverse reactions between the two groups.

CONCLUSION: Mesalazine could significantly improve clinical outcome and relieve abdominal pain of patients with irritable bowel syndrome, without significant adverse reactions.

Meta-analysis of mesalazine for irritable bowel syndrome

AIM: To evaluate the efficacy and safety of mesalazine for irritable bowel syndrome.

METHODS: Online databases, including China National Knowledge Infrastructure database (CNKI), VIP database, Wanfang database, PubMed, MEDLINE and Cochrane Library, were searched for randomized controlled trials of mesalazine for irritable bowel syndrome. After assessing the methodological strength, we extracted relevant data from the included studies to conduct a meta-analysis.

RESULTS: Based on the inclusion and exclusion criteria, 13 randomized controlled trails with a total of 1349 patients were included in this study. Clinical remission rate and abdominal pain score were significantly improved in the mesalazine group when compared with the control group. However, there was no significant difference in adverse reactions between the two groups.

CONCLUSION: Mesalazine could significantly improve clinical outcome and relieve abdominal pain of patients with irritable bowel syndrome, without significant adverse reactions.