Changes of faecal microbiota in patients with Crohn's disease treated with an elemental diet and total parenteral nutrition

Gut Microbiota Serves as a Crucial Independent Biomarker in Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD), ulcerative colitis (UC), and IBD unclassified (IBD-U), is a complex intestinal disorder influenced by genetic, environmental, and microbial factors. Recent evidence highlights the gut microbiota as a pivotal biomarker and modulator in IBD pathogenesis. Dysbiosis, characterized by reduced microbial diversity and altered composition, is a hallmark of IBD. A consistent decrease in anti-inflammatory bacteria, such as Faecalibacterium prausnitzii, and an increase in pro-inflammatory species, including Escherichia coli, have been observed. Metabolomic studies reveal decreased short-chain fatty acids (SCFAs) and secondary bile acids, critical for gut homeostasis, alongside elevated pro-inflammatory metabolites. The gut microbiota interacts with host immune pathways, influencing morphogens, glycosylation, and podoplanin (PDPN) expression. The disruption of glycosylation impairs mucosal barriers, while aberrant PDPN activity exacerbates inflammation. Additionally, microbial alterations contribute to oxidative stress, further destabilizing intestinal barriers. These molecular and cellular disruptions underscore the role of the microbiome in IBD pathophysiology. Emerging therapeutic strategies, including probiotics, prebiotics, and dietary interventions, aim to restore microbial balance and mitigate inflammation. Advanced studies on microbiota-targeted therapies reveal their potential to reduce disease severity and improve patient outcomes. Nevertheless, further research is needed to elucidate the bidirectional interactions between the gut microbiome and host immune responses and to translate these insights into clinical applications. This review consolidates current findings on the gut microbiota's role in IBD, emphasizing its diagnostic and therapeutic implications, and advocates for the continued exploration of microbiome-based interventions to combat this debilitating disease.

Factors Affecting the Gut Microbiome in Pediatric Intestinal Failure

BACKGROUND

There is little data on gut microbiome and various factors that lead to dysbiosis in pediatric intestinal failure (PIF). This study aimed to characterize gut microbiome in PIF and determine factors that may affect microbial composition in these patients.

METHODS

This is a single-center, prospective cohort study of children with PIF followed at our intestinal rehabilitation program. Stool samples were collected longitudinally at regular intervals over a 1-year period. Medical records were reviewed, and demographic and clinical data were collected. Medication history including the use of acid blockers, scheduled prophylactic antibiotics, and bile acid sequestrants was obtained. Gut microbial diversity among patients was assessed and compared according to various host characteristics of interest.

RESULTS

The final analysis included 74 specimens from 12 subjects. Scheduled prophylactic antibiotics, presence of central line associated bloodstream infection (CLABSI) at the time of specimen collection, use of acid blockers, and ≥50% calories delivered via parenteral nutrition (PN) was associated with reduced alpha diversity, whereas increasing age was associated with improved alpha diversity at various microbial levels ( P value <0.05). Beta diversity differed with age, presence of CLABSI, use of scheduled antibiotics, acid blockers, percent calories via PN, and presence of oral feeds at various microbial levels ( P value <0.05). Single taxon analysis identified several taxa at several microbial levels, which were significantly associated with various host characteristics.

CONCLUSION

Gut microbial diversity in PIF subjects is influenced by various factors involved in the rehabilitation process including medications, percent calories received parenterally, CLABSI events, the degree of oral feeding, and age. Additional investigation performed across multiple centers is needed to further understand the impact of these findings on important clinical outcomes in PIF.

Association between Taxonomic Composition of Gut Microbiota and Host Single Nucleotide Polymorphisms in Crohn's Disease Patients from Russia

Crohn's disease (CD) is a chronic relapsing inflammatory bowel disease of unknown etiology. Genetic predisposition and dysbiotic gut microbiota are important factors in the pathogenesis of CD. In this study, we analyzed the taxonomic composition of the gut microbiota and genotypes of 24 single nucleotide polymorphisms (SNP) associated with the risk of CD. The studied cohorts included 96 CD patients and 24 healthy volunteers from Russia. Statistically significant differences were found in the allele frequencies for 8 SNPs and taxonomic composition of the gut microbiota in CD patients compared with controls. In addition, two types of gut microbiota communities were identified in CD patients. The main distinguishing driver of bacterial families for the first community type are Bacteroidaceae and unclassified members of the Clostridiales order, and the second type is characterized by increased abundance of Streptococcaceae and Enterobacteriaceae. Differences in the allele frequencies of the rs9858542 (BSN), rs3816769 (STAT3), and rs1793004 (NELL1) were also found between groups of CD patients with different types of microbiota communities. These findings confirm the complex multifactorial nature of CD.

Multi-drug resistant ESKAPE pathogens and the uses of plants as their antimicrobial agents

Infections by ESKAPE (Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens cause major concern due to their multi-drug resistance (MDR). The ESKAPE pathogens are frequently linked to greater mortality, diseases, and economic burden in healthcare worldwide. Therefore, the use of plants as a natural source of antimicrobial agents provide a solution as they are easily available and safe to use. These natural drugs can also be enhanced by incorporating silver nanoparticles and combining them with existing antibiotics. By focussing the attention on the ESKAPE organisms, the MDR issue can be addressed much better.

Gut Microbiota Composition Changes following Discontinuation of Exclusive Enteral Nutrition in Children with Crohn's Disease

This study aims to determine changes in the intestinal microbiota of children with Crohn's disease (CD) before and during exclusive enteral nutrition (EEN) and after its discontinuation. A total of 14 newly diagnosed children with CD (median age 16.0 years; 43% female) were included in this study. Patients were initially treated with EEN and were followed for one year after EEN discontinuation. Stool samples were taken at the time of diagnosis (before EEN introduction), the second day of EEN, the last day of EEN, and every two months for one year after the discontinuation of EEN. A molecular approach targeting 16S ribosomal RNA was used for analysing the gut microbiota. No change was found in the Shannon diversity index before, during, and after EEN cessation (HhaI-digestion p = 0.82; MspI-digestion p = 0.87). According to the PCO, on the basis of the dissimilarity matrices of OTUs, a clear separation of patients at different time points, forming two clusters (before and during EEN as opposed to after EEN), was evident. No clear separation was noted between patients who achieved sustained remission as opposed to those who did not achieve sustained remission during EEN and at the follow-up. In conclusion, a distinct change in the microbiota composition already occurred after two months of EEN discontinuation and remained mostly unchanged over a year of follow-up.

Metabolic changes during exclusive enteral nutrition in pediatric Crohn's disease patients

BACKGROUND AND AIMS

Exclusive enteral nutrition is recommended as a first-line treatment in active pediatric Crohn's Disease, but its mechanism of action is still not clear. We aimed to assess alterations in the metabolic profile of newly diagnosed pediatric Crohn's Disease patients before and during exclusive enteral nutrition therapy.

METHODS

Plasma samples from 14 pediatric Crohn's Disease patients before and after 3-4 weeks on exclusive enteral nutrition were analyzed using mass spectrometry. T-test, fold change and orthogonal partial least squares discriminant analysis were used for mining significant features. Correlation analysis was performed between the annotated features and the weighted pediatric Crohn's disease activity index using Pearson r distance.

RESULTS

Among the 13 compounds which decreased during exclusive enteral nutrition, most are related to diet, while one is a bacterial metabolite, Bacteriohopane-32,33,34,35-tetrol. The phosphatidic acid metabolite PA(15:1/18:0) was significantly reduced and correlated with the weighted pediatric Crohn's disease activity index. Lipids increased during exclusive enteral nutrition therapy included phosphatidylethanolamines; PE(24:1/24:1), PE(17:2/20:2) and one lactosylceramide; LacCer(d18:1/14:0).

CONCLUSION

Food additives and other phytochemicals were the major metabolites, which decreased following the exclusion of a regular diet during exclusive enteral nutrition. An alteration in bacterial biomarkers may reflect changes in intestinal microbiota composition and metabolism. Thus, metabolomics provides an opportunity to characterize the molecular mechanisms of dietary factors triggering Crohn's Disease activity, and the mechanisms of action of exclusive enteral nutrition, thereby providing the basis for the development and evaluation of improved intervention strategies for prevention and treatment.

Therapeutic Advances in Gut Microbiome Modulation in Patients with Inflammatory Bowel Disease from Pediatrics to Adulthood

There is mounting evidence that the gut microbiota plays an important role in the pathogenesis of inflammatory bowel disease (IBD). For the past decade, high throughput sequencing-based gut microbiome research has identified characteristic shifts in the composition of the intestinal microbiota in patients with IBD, suggesting that IBD results from alterations in the interactions between intestinal microbes and the host’s mucosal immune system. These studies have been the impetus for the development of new therapeutic approaches targeting the gut microbiome, such as nutritional therapies, probiotics, fecal microbiota transplant and beneficial metabolic derivatives. Innovative technologies can further our understanding of the role the microbiome plays as well as help to evaluate how the different approaches in microbiome modulation impact clinical responses in adult and pediatric patients. In this review, we highlight important microbiome studies in patients with IBD and their response to different microbiome modulation therapies, and describe the differences in therapeutic response between pediatric and adult patient cohorts.

Diet and gut microbiota manipulation for the management of Crohn's disease and ulcerative colitis

The aetiology of inflammatory bowel disease (IBD) is multifactorial, with diet and gut microbiota playing an important role. Nonetheless, there are very few studies, particularly clinical research, which have explored the interaction between diet and gut microbiota. In the current review, we summarise the evidence from clinical trials exploring the interactions between the gut microbiota and diet in the management of IBD. Data from the effect of exclusive enteral nutrition (EEN) on the gut microbiota of children with active Crohn's disease (CD), receiving induction treatment, offer opportunities to understand the role of gut microbiota in underlying disease pathogenesis and develop novel dietary and pharmacological microbial therapeutics. In contrast, the evidence which links the effectiveness of food-based dietary therapies for IBD with mechanisms involving the gut microbiota is far less convincing. The microbial signals arising from these dietary therapies are inconsistent and vary compared to the effects of effective treatment with EEN in CD.

Sustained Crohn’s Disease Remission with an Exclusive Elemental and Exclusion Diet: A Case Report

The incidence of inflammatory bowel diseases, such as Crohn’s disease (CD), is increasing worldwide. Despite several new therapeutics to treat CD, many patients fail to respond to their medications and inevitably face surgical resection. While genetics plays a role in CD, environmental factors are potential triggers. Recent research from the past few years suggest that pro-inflammatory foods are associated with an increased risk of CD. Some studies have shown the benefit of including exclusion diets, such as the specific carbohydrate diet (SCD) and exclusive elemental diets, to induce CD remission, but published data is limited. This case study explores how an exclusive elemental and exclusion diet helped induce clinical and biochemical remission and radiologic healing in a young adult male who had failed to achieve remission using standard medical treatment. C-reactive protein (CRP), fecal calprotectin, and magnetic resonance enterography (MRE) served as objective markers of inflammation in this study.

The role of precision nutrition in the modulation of microbial composition and function in people with inflammatory bowel disease

Inflammatory bowel diseases, principally Crohn's disease and ulcerative colitis, are multifactorial chronic conditions. Alterations in gut microbial patterns partly affect disease onset and severity. Moreover, the evolution of dietary patterns, and their effect on gut microbial behaviour, have been shown to play a crucial role in disease processes. This Viewpoint reviews the role of dietary patterns, their influence on the structure and function of the gut microbiome, and their effects on inflammation and immunity in individuals with inflammatory bowel disease. We also discuss innovative dietary intervention strategies, summarise findings that have been used to develop recommendations for clinical practice, and provide suggestions for the design of future studies for development of precision nutrition in patients with inflammatory bowel disease.

Restoration of dysbiotic human gut microbiome for homeostasis

The human microbiome is a complex and dynamic ecosystem, and the imbalance of its microbial community structure from the normal state is termed dysbiosis. The dysbiotic gut microbiome has been proved to be related to several pathological conditions like Inflammatory Bowel Disease (IBD), Irritable Bowel Syndrome (IBS), Colorectal Cancer (CRC), etc., and several other extra-intestinal conditions like Type 1 & 2 diabetes, obesity, etc. The complex gut microbial ecosystem starts to build before the birth of an individual. It is known to get affected by several factors such as birth mode, individual lifestyle, dietary practices, medications, and antibiotics. A dysbiotic microbiome can potentially hamper host homeostasis due to its role in immune modulation, metabolism, nutrient synthesis, etc. Restoration of the dysbiotic gut microbiome has emerged as a promising aid and a better therapeutic approach. Several approaches have been investigated to achieve this goal, including prebiotics and probiotics, Fecal Microbiota Transplantation (FMT), extracellular vesicles, immune modulation, microbial metabolites, dietary interventions, and phages. This review discusses the various factors that influence the human microbiome with respect to their cause-effect relationship and the effect of gut microbiome compositional changes on the brain through the gut-brain axis. We also discuss the practices used globally for gut microbiome restoration purposes, along with their effectiveness.

Dietary Therapies Induce Rapid Response and Remission in Pediatric Patients With Active Crohn's Disease

BACKGROUND & AIMS

Dietary therapies based on exclusion of usual dietary elements induce remission in children with Crohn's disease (CD), whereas re-exposure induces rebound inflammation. We investigated whether a short trial of dietary therapy, to identify patients with and without a rapid response or remission on the diet (DiRe), can be used to predict success or failure of long-term dietary therapy.

METHODS

We collected data from the multicenter randomized trial of the CD exclusion diet (CDED). We analyzed data from 73 children with mild to moderate CD (mean age, 14.2 ± 2.7 y) randomly assigned to groups given either exclusive enteral nutrition (EEN, n = 34) or the CDED with 50% (partial) enteral nutrition (n = 39). Patients were examined at baseline and at weeks 3 and 6 of the diet. Remission was defined as CD activity index scores below 10 and response was defined as a decrease in score of 12.5 points or clinical remission. Inflammation was assessed by measurement of C-reactive protein.

RESULTS

At week 3 of the diet, 82% of patients in the CDED group and 85% of patients in the EEN group had a DiRe. Median serum levels of C-reactive protein had decreased from 24 mg/L at baseline to 5.0 mg/L at week 3 (P < .001). Among the 49 patients in remission at week 6, 46 patients (94%) had a DiRe and 81% were in clinical remission by week 3. In multivariable analysis, remission at week 3 increased odds of remission by week 6 (odds ratio, 6.37; 95% CI, 1.6-25; P = .008) whereas poor compliance reduced odds of remission at week 6 (odds ratio, 0.75; 95% CI, 0.012-0.46; P = .006).

CONCLUSIONS

For pediatric patients with active CD, dietary therapies (CDED and EEN) induce a rapid clinical response (by week 3). Identification of patients with and without a rapid response to diet might help identify those who, with compliance, will be in clinical remission by week 6 of the diet. ClinicalTrials.gov no: NCT01728870.

Nutrition and the gut microbiome during critical illness: A new insight of nutritional therapy

Changes in the microbiome in response to environmental influences can affect the overall health. Critical illness is considered one of the major environmental factors that can potentially influence the normal gut homeostasis. It is associated with pathophysiological effects causing damage to the intestinal microbiome. Alteration of intestinal microbial composition during critical illness may subsequently compromise the integrity of the intestinal epithelial barrier and intestinal mucosa absorptive function. Many factors can impact the microbiome of critically ill patients including ischemia, hypoxia and hypotension along with the iatrogenic effects of therapeutic agents and the lack of enteral feeds. Factors related to disease state and medication are inevitable and they are part of the intensive care unit (ICU) exposure. However, a nutritional intervention targeting gut microbiota might have the potential to improve clinical outcomes in the critically ill population given the extensive vascular and lymphatic links between the intestines and other organs. Although nutrition is considered an integral part of the treatment plan of critically ill patients, still the role of nutritional intervention is restricted to improve nitrogen balance. What is dismissed is whether the nutrients we provide are adequate and how they are processed and utilised by the host and the microbiota. Therefore, the goal of nutrition therapy during critical illness should be extended to provide good quality feeds with balanced macronutrient content to feed up the entire body including the microbiota and host cells. The main aim of this review is to examine the current literature on the effect of critical illness on the gut microbiome and to highlight the role of nutrition as a factor affecting the intestinal microbiome-host relationship during critical illness.

Healthy Siblings of Children With Crohn's Disease Exhibit More Rapid Changes in Microbiota Composition as a Response to Exclusive Enteral Nutrition

BACKGROUND

The aim of this study was to determine the impact of exclusive enteral nutrition (EEN) on the microbiota composition of the newly diagnosed Crohn's disease (CD) patients and to determine the effect of EEN received for 2 days in siblings of patients with CD.

METHODS

Newly diagnosed pediatric CD patients (n = 17) and unaffected healthy siblings (n = 10) participated in the study. In CD patients, stool samples were collected at 3 time points: prior to therapy introduction, the second day of EEN therapy, and the last day of EEN therapy. In healthy siblings, stool samples were collected before the introduction of EEN and the second day of EEN. Molecular approach targeting 16S ribosomal RNA was used for analyzing the gut microbiota of participants' stool samples.

RESULTS

There was no significant difference in microbial diversity between children with CD and healthy siblings before EEN (P = .127 for HhaI digestion; P = .604 for MspI digestion) as opposed to the second day of EEN (P = .006 HhaI digestion; P = .023 MspI digestion). In healthy controls, significant changes in microbiota composition were apparent by the second day of EEN, contrary to children with CD, in whom similar changes in microbiota composition were apparent on the last day of EEN.

CONCLUSION

EEN leads to significant microbiota changes in both healthy children and children with CD. Changes in microbiota composition occur more rapidly in healthy children, whereas in children with CD, significant changes were detected at the end of EEN.

Influence of Enteral Nutrition on Gut Microbiota Composition in Patients with Crohn's Disease: A Systematic Review

The aim of the study was to systematically and comprehensively evaluate whether exclusive enteral nutrition (EEN) has impact on gut microbiota in patients with Crohn's disease (CD). The databases PUBMED (MEDLINE), SCOPUS and WEB OF SCIENCE were searched. Out of 232 studies, 9 met inclusion criteria. The combined analyzed population consists of 118 patients with CD and treated with EEN with a time of intervention of 2-12 weeks. Studies were conducted in children, with the exception of one study. All applied feeding formulas had similar energy value and composition. The microbiome analysis was based on 16S rRNA gene sequencing of faecal samples. In all studies, EEN treatment decreases inflammatory markers (i.e., hs-CRP and FCP). A change in abundance of numerous bacterial families (Clostridiaceae, Eubacteriaceae, Bacteroidaceae) was noticed, especially in Bacteroidaceae. An increase in families connected to the more severe clinical course (Fusobacteria, Prevotella, Lachnospiraceae) was observed in only 2.5% of CD patients. Our analyses suggest EEN has a beneficial influence on gut microbiome in patients with CD, which is interrelated with clinical patient's improvement and time of disease remission.

Nutrition Support and the Gastrointestinal Microbiota: A Systematic Review

BACKGROUND

Low microbial diversity or altered microbiota composition is associated with many disease states. In the treatment of many conditions, enteral (EN) or parenteral (PN) nutrition is frequently required.

OBJECTIVE

This systematic review aimed to identify and evaluate the evidence of the effect of EN vs PN on the gastrointestinal microbiota.

METHOD

A comprehensive systematic literature search of 5 databases was completed to review studies published until February 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized in completion of the review with the Academy of Nutrition and Dietetics quality criteria checklist and Grading of Recommendations Assessment, Development and Evaluation to evaluate the included studies. The review was registered on PROSPERO (CRD42018091328). Studies were eligible for inclusion if participants were older than 3 years, patients received either EN, PN or both, with some patients receiving each mode of nutrition support. The main outcome was any assessment of the gastrointestinal microbiota, including diversity or taxa abundance.

RESULTS

Eleven articles (n = 367 patients) met the inclusion criteria and were evaluated. Seven studies (n = 237) reported greater abundance of Proteobacteria with the provision of PN compared to EN; 6 studies (n = 172) reported lower Firmicutes and 5 studies (n = 155) lower Bacteroidetes. In 7 studies (n = 282), microbial diversity was lower with provision of PN than EN. The Grading of Recommendations Assessment, Development and Evaluation certainty of evidence was very low.

CONCLUSIONS

Provision of PN may lead to greater abundance of Proteobacteria and reduced microbial diversity; however, there is limited literature on this topic and additional research is warranted to improve understanding of the impact of EN vs PN on the microbiota.

Effect of Exclusive Enteral Nutrition on the Disease Process, Nutrition Status, and Gastrointestinal Microbiota for Chinese Children With Crohn's Disease

BACKGROUND

The aim of this study was to prospectively study the effect of exclusive enteral nutrition (EEN) treatment on Chinese pediatric Crohn's disease (CD) patients.

METHODS

Thirty-one newly diagnosed CD patients were enrolled in this study and treated with EEN for 8 weeks. Twelve healthy controls (HCs) donated their fecal samples. Statistical methods were used to compare the differences.

RESULTS

According to the Simple Endoscopic Score for CD (SES-CD) at the end of the EEN treatment, 21 patients with SES-CD ≤4 were classified into the remission group (CD-RE), and 10 patients with SES-CD >4 were classified into the nonremission group (CD-NRE). After EEN therapy, there was a significant decrease in the SES-CD, the weighted Pediatric Crohn's Disease Activity Index (wPCDAI), and fecal calprotectin (FCP) in the CD-RE group (all P < .001). The wPCDAI and FCP also decreased in the CD-NRE group (both P < .05). In terms of nutrition improvement, the CD-RE group patients showed more improvement in weight gain, hemoglobin, and serum albumin level than the CD-NRE group patients (all P < .05). For the microbiota, the CD patients had a lower bacterial diversity and different bacterial community compared with HCs. EEN increased overall diversity and was able to shift the dysbiosis in CD patients toward a healthier state. Absence of improvement in wPCDAI and Shannon index at 2 weeks predicts poor response at the end of EEN.

CONCLUSION

EEN can be used in most Chinese pediatric CD patients to induce remission and improve nutrition.

Preoperative enteral nutrition in adults with complicated Crohn's disease: Effect on disease outcomes and gut microbiota

OBJECTIVES

The use of exclusive enteral nutrition (EEN) in patients with Crohn's disease (CD) before surgical resection can reduce disease activity and improve nutritional status. The mechanism of EEN action is unclear, but it might involve modulation of the intestinal microbiota. The aim of this study was to evaluate the effects (namely changes in gut microbiota) of preoperative EEN in adults with complicated CD referred to surgery.

METHODS

This was a prospective study of adult patients with CD referred to surgery. Patients with body mass index <18.5 kg/m², weight loss >10 %, serum albumin <3 g/dL, or a combination of some or all three, received EEN for ≥2 wk. The effects of EEN on clinical (Harvey-Bradshaw Index [HBI]) and laboratory markers (C-reactive protein [CRP], serum albumin, and fecal calprotectin) and fecal microbiota were analyzed after EEN (before surgery) and 6 mo later. We used 16 S rRNA gene sequencing to determine changes in the fecal microbiota.

RESULTS

Fifteen patients were included, of whom 60% were men with a mean age of 45.4 ± 19.1 y. Of those, 10 received EEN. The median duration of preoperative EEN was 41.5 d (15-70 d). During EEN, there was a significant reduction in mean HBI (8.7 ± 1.9 versus 4.1 ± 2.4; P = 0.001) and CRP (11.7 ± 10.3 versus 0.8 ± 0.8 mg/dL; P = 0.008) and an increase in serum albumin (3.1 ± 0.6 versus 4 ± 0.6 g/dL; P = 0.022). Two patients did not require surgery after EEN. The overall microbial composition changed after EEN (Permutational analysis of variance test, P = 0.046) and there was a significant reduction in α diversity (8 ± 2.3 versus 5.2 ± 1.5; P = 0.023). EEN significantly changed the relative abundance of 11 taxonomic operational units (OTUs). At the family level, we found this was mainly due to the decrease in the Enterobacteriaceae family (7 OTUs). Six months after surgery, α diversity was not different from that before or after EEN; at this time point 6 OTUs were significantly different, mainly due to the decrease of Clostridiales order (3 OTUs). The incidence of postoperative complications and hospital length of stay were similar in EEN and immediate surgery groups, as well as clinical and endoscopic recurrence rates 6 mo after surgery.

CONCLUSIONS

Preoperative EEN improved disease activity and nutritional status in patients with CD referred to surgery. Despite being malnourished, patients given EEN did not have increased postoperative complications compared with well-nourished patients. During EEN, overall microbiota composition changed and α diversity decreased. EEN did not influence postoperative recurrence and gut microbiota 6 mo after surgery.

Differences in Gut Microbiota in Patients With vs Without Inflammatory Bowel Diseases: A Systematic Review

BACKGROUND & AIMS

Altering the intestinal microbiota has been proposed as a treatment for inflammatory bowel diseases (IBDs), but there are no established associations between specific microbes and IBD. We performed a systematic review to identify frequent associations.

METHODS

We searched the MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials databases, through April 2, 2018 for studies that compared intestinal microbiota (from fecal or colonic or ileal tissue samples) among patients (adult or pediatric) with IBD vs healthy individuals (controls). The primary outcome was difference in specific taxa in fecal or intestinal tissue samples from patients with IBD vs controls. We used the Newcastle-Ottawa scale to assess the quality of studies included in the review.

RESULTS

We identified 2631 citations; 48 studies from 45 articles were included in the analysis. Most studies evaluated adults with Crohn's disease or ulcerative colitis. All 3 studies of Christensenellaceae and Coriobacteriaceae and 6 of 11 studies of Faecalibacterium prausnitzii reported a decreased amount of those organisms compared with controls, whereas 2 studies each of Actinomyces, Veillonella, and Escherichia coli revealed an increased amount in patients with Crohn's disease. For patients with ulcerative colitis, Eubacterium rectale and Akkermansia were decreased in all 3 studies, whereas E coli was increased in 4 of 9 studies. The microbiota diversity was either decreased or not different in patients with IBD vs controls. Fewer than 50% of the studies stated comparable sexes and ages of cases and controls.

CONCLUSIONS

In a systematic review, we found evidence for differences in abundances of some bacteria in patients with IBD vs controls, but we cannot make conclusions due to inconsistent results and methods among studies. Further large-scale studies, with better methods of assessing microbe populations, are needed.

Pilot study investigating the effect of enteral and parenteral nutrition on the gastrointestinal microbiome post-allogeneic transplantation

Nutrition support is frequently required post-allogeneic haematopoietic progenitor cell transplantation (HPCT); however, the impact of mode of feeding on the gastrointestinal microbiome has not been explored. This study aimed to determine if there is a difference in the microbiome between patients receiving enteral nutrition (EN) and parenteral nutrition (PN) post-allogeneic HPCT. Twenty-three patients received either early EN or PN when required. Stool samples were collected at 30 days post-transplant and analysed with shotgun metagenomic sequencing. There was no difference in microbial diversity between patients who received predominantly EN (n = 13) vs. PN (n = 10) however patients who received predominantly EN had greater abundance of Faecalibacterium (P < 0·001) and ruminococcus E bromii (P = 0·026). Patients who had minimal oral intake for a longer duration during provision of nutrition support had a different overall microbial profile (P = 0·044), lower microbial diversity (P = 0·004) and lower abundance of faecalibacterium prausnitzii_C (P = 0·030) and Blautia (P = 0·007) compared to patients with greater oral intake. Lower microbial diversity was found in patients who received additional beta lactam antibiotics (P = 0·042) or had a longer length of hospital stay (P = 0·019). Post-HPCT oral intake should be encouraged to maintain microbiota diversity and, if nutrition support is required, EN may promote a more optimal microbiota profile.

Enteral Nutrition as a Growth Medium for Cultivable Commensal Bacteria and Its Effect on Their Quantity in the Stool of Children with Crohn's Disease

Current studies indicate a link between the intake of exclusive enteral nutrition (EEN) and the induction of complex changes in the intestinal microbiota, as well as the clinical improvement of Crohn's disease (CD). The first aim of this study was to test the ability of various commensal bacterial strains (n = 19) such as bifidobacteria, lactobacilli, and Escherichia coli to grow on three different polymeric EN in vitro. Tested EN formulas were found to be suitable growth media for tested commensals. Furthermore, the counts of these bacteria and total counts of anaerobic bacteria in the fecal samples of children with CD (n = 15) before and after 6 weeks of EEN diet administration were determined using cultivation on selective media. The counts of cultivable commensal bacteria in the fecal samples of CD children were not significantly affected by EEN. However, tested bacteria showed some individual shifts in counts before and after EEN therapy. Moreover, cultured bifidobacteria were found to be in reduced counts in CD children. Therefore, the application of bifidogenic prebiotic compounds to EN for CD patients might be considered.

Pathogenicity of Enterococci

Enterococci are unusually well adapted for survival and persistence in a variety of adverse environments, including on inanimate surfaces in the hospital environment and at sites of infection. This intrinsic ruggedness undoubtedly played a role in providing opportunities for enterococci to interact with other overtly drug-resistant microbes and acquire additional resistances on mobile elements. The rapid rise of antimicrobial resistance among hospital-adapted enterococci has rendered hospital-acquired infections a leading therapeutic challenge. With about a quarter of a genome of additional DNA conveyed by mobile elements, there are undoubtedly many more properties that have been acquired that help enterococci persist and spread in the hospital setting and cause diseases that have yet to be defined. Much remains to be learned about these ancient and rugged microbes, particularly in the area of pathogenic mechanisms involved with human diseases.

Longitudinal changes in the gut microbiome of infants on total parenteral nutrition

BACKGROUND

Animal studies suggest that total parenteral nutrition (TPN) may alter bacterial colonization of the intestinal tract and contribute to complications. Progressive changes in gut microbiome of infants receiving TPN are not well understood.

METHODS

Infants with and without TPN/soy lipid were enrolled in a prospective, longitudinal study. Weekly fecal samples were obtained for the first 4 weeks of life. High throughput pyrosequencing of 16S rDNA was used for compositional analysis of the gut microbiome.

RESULTS

47 infants were eligible for analyses, 25 infants received TPN, and 22 infants did not (control). Although similar between TPN and control groups in the first week, fecal bacterial alpha diversity was significantly lower in the TPN group compared to controls at week 4 (Shannon index 1.0 vs 1.5, P-value = 0.03). The TPN group had significantly lower Bacteroidetes and higher Verrucomicrobia abundance compared to controls (P-values < 0.05), and these differences became more pronounced over time. At the genus level, TPN was associated with lower abundance of Bacteroides and Bifidobacterium in all weeks.

CONCLUSIONS

TPN is associated with significant loss of biodiversity and alterations in the pattern of gut microbial colonization of infants over time. TPN-associated dysbiosis may predispose infants to adverse NICU outcomes.

Complex Bacterial Consortia Reprogram the Colitogenic Activity of Enterococcus faecalis in a Gnotobiotic Mouse Model of Chronic, Immune-Mediated Colitis

Inflammatory bowel diseases (IBD) are associated with compositional and functional changes of the intestinal microbiota, but specific contributions of individual bacteria to chronic intestinal inflammation remain unclear. Enterococcus faecalis is a resident member of the human intestinal core microbiota that has been linked to the pathogenesis of IBD and induces chronic colitis in susceptible monoassociated IL-10-deficient (IL-10^−/−) mice. In this study, we characterized the colitogenic activity of E. faecalis as part of a simplified human microbial consortium based on seven enteric bacterial strains (SIHUMI). RNA sequencing analysis of E. faecalis isolated from monoassociated wild type and IL-10^−/− mice identified 408 genes including 14 genes of the ethanolamine utilization (eut) locus that were significantly up-regulated in response to inflammation. Despite considerable up-regulation of eut genes, deletion of ethanolamine utilization (ΔeutVW) had no impact on E. faecalis colitogenic activity in monoassociated IL-10^−/− mice. However, replacement of the E. faecalis wild type bacteria by a ΔeutVW mutant in SIHUMI-colonized IL-10^−/− mice resulted in exacerbated colitis, suggesting protective functions of E. faecalis ethanolamine utilization in complex bacterial communities. To better understand E. faecalis gene response in the presence of other microbes, we purified wild type E. faecalis cells from the colon content of SIHUMI-colonized wild type and IL-10^−/− mice using immuno-magnetic separation and performed RNA sequencing. Transcriptional profiling revealed that the bacterial environment reprograms E. faecalis gene expression in response to inflammation, with the majority of differentially expressed genes not being shared between monocolonized and SIHUMI conditions. While in E. faecalis monoassociation a general bacterial stress response could be observed, expression of E. faecalis genes in SIHUMI-colonized mice was characterized by up-regulation of genes involved in growth and replication. Interestingly, in mice colonized with SIHUMI lacking E. faecalis enhanced inflammation was observed in comparison to SIHUMI-colonized mice, supporting the hypothesis that E. faecalis ethanolamine metabolism protects against colitis in complex consortia. In conclusion, this study demonstrates that complex bacterial consortia interactions reprogram the gene expression profile and colitogenic activity of the opportunistic pathogen E. faecalis toward a protective function.

Gut dysbiosis and paediatric Crohn's disease

OBJECTIVES

The main objective of this manuscript is to discuss our present knowledge of the relationships between dysbiosis and paediatric Crohn's disease (CD). The therapeutic role of the methods currently used to re-establish normal gut microbiota composition is also analysed.

METHODS

PubMed was used to search for all of the studies published from January 2008 to June 2018 using the key words: "Crohn's disease" and "gut dysbiosis" or "microbiota" or "microbioma" or "probiotic" and "children" or "paediatric". More than 100 articles were found, but only those published in English or providing evidence-based data were included in the evaluation.

RESULTS

Gut microbiota are primary actors in CD's pathogenesis. The new techniques developed in metagenomics allow us to reveal new details of microbiota composition in healthy subjects and CD patients, and to elucidate the link between microbiota and numerous pathologies, such as obesity, allergies and type 1 diabetes mellitus.

CONCLUSION

Discoveries on the role of gut microbiota could potentially disclose new therapeutic options for CD treatment and improve the existing therapies. Further studies are needed to facilitate the diagnosis and tailor the therapy of a pathology that is an increasing burden on public health.

Dietary Interventions to Modulate the Gut Microbiome-How Far Away Are We From Precision Medicine

The importance of the gut microbiome in human health and disease is fully acknowledged. A perturbation in the equilibrium among the different microbial populations living in the gut (dysbiosis) has been associated with the development of several types of diseases. Modulation of the gut microbiome through dietary intervention is an emerging therapeutic and preventive strategy for many conditions. Nevertheless, interpersonal differences in response to therapeutic treatments or dietary regimens are often observed during clinical trials, and recent research has suggested that subject-specific features of the gut microbiota may be responsible. In this review, we summarize recent findings in personalized nutrition, highlighting how individualized characterization of the microbiome may assist in designing ad hoc tailored dietary intervention for disease treatment and prevention. Moreover, we discuss the limitations and challenges encountered in integrating patient-specific microbial data into clinical practice.

The impact of exclusive enteral nutrition on the intestinal microbiota in inflammatory bowel disease

It is increasingly clear that the intestinal microbiota plays key roles in the pathogenesis of the conditions known as Crohn disease and ulcerative colitis (jointly known as the inflammatory bowel diseases). Perturbations of the microbiota, termed dysbiosis, are present at diagnosis and likely reflect earlier environmental influences along with interactions with intestinal immune responses. Over the last two decades, there has been increasing interest in the use of a nutritional therapy to induce remission of active Crohn disease. Amongst a number of recent studies focusing on the putative mechanisms of action of enteral nutrition in Crohn disease, there have been several reports illustrating profound interactions between this nutritional therapy and the intestinal microbiota. Although at present it is still not clear how these changes relate to concurrent improvements in inflammation, it has become an area of increasing interest. This review article focuses on the impacts of nutritional therapy in individuals with active Crohn disease and overviews the most recent data arising from international studies.

Reasoning Beyond the Potential Use of Exclusive Enteral Nutrition and Other Specified Diets in Children With Ulcerative Colitis

The incidence of inflammatory bowel disease (IBD) is steadily on the rise in Western and in developing countries paralleling the increase of westernized diets, characterized by high protein and fat as well as excessive sugar intake, with less vegetables and fiber. Furthermore, nutrition is involved in several aspects of pediatric IBD, ranging from disease etiology to induction and maintenance of remission of disease. Exclusive enteral nutrition (EEN) has been shown to induce remission, including in patients with isolated colonic disease, and leads to mucosal healing in Crohn disease. One hypothesis for the beneficial effect of this modality is exclusion of dietary components thought to cause dysbiosis or impair innate immune mechanisms such as the mucous layer, intestinal permeability or colonization and adherence with adherent-invasive Escherichia coli. Although there is not yet definitive data illustrating a role for EEN in the management of active ulcerative colitis (UC), there are several lines of evidence that illustrate that dietary interventions may be helpful. In particular, the key mechanisms of the activity of EEN (namely, changes in the intestinal microflora in Crohn disease) are likely also relevant to UC. Furthermore, the use of EEN in pediatric UC patients may add to a better bone health. Prospective studies are now required to evaluate the role of EEN in UC in children.

Research Gaps in Diet and Nutrition in Inflammatory Bowel Disease. A Topical Review by D-ECCO Working Group [Dietitians of ECCO]

Although the current doctrine of IBD pathogenesis proposes an interaction between environmental factors and gut microbiota in genetically susceptible individuals, dietary exposures have attracted recent interest and are, at least in part, likely to explain the rapid rise in disease incidence and prevalence. The D-ECCO working group along with other ECCO experts with expertise in nutrition, microbiology, physiology, and medicine reviewed the evidence investigating the role of diet and nutritional therapy in the onset, perpetuation, and management of IBD. A narrative topical review is presented where evidence pertinent to the topic is summarised collectively under three main thematic domains: i] the role of diet as an environmental factor in IBD aetiology; ii] the role of diet as induction and maintenance therapy in IBD; and iii] assessment of nutritional status and supportive nutritional therapy in IBD. A summary of research gaps for each of these thematic domains is proposed, which is anticipated to be agenda-setting for future research in the area of diet and nutrition in IBD.

Complementary and Alternative Medicine Strategies for Therapeutic Gut Microbiota Modulation in Inflammatory Bowel Disease and their Next-Generation Approaches

The human gut microbiome exerts a major impact on human health and disease, and therapeutic gut microbiota modulation is now a well-advocated strategy in the management of many diseases, including inflammatory bowel disease (IBD). Scientific and clinical evidence in support of complementary and alternative medicine, in targeting intestinal dysbiosis among patients with IBD, or other disorders, has increased dramatically over the past years. Delivery of "artificial" stool replacements for fecal microbiota transplantation (FMT) could provide an effective, safer alternative to that of human donor stool. Nevertheless, optimum timing of FMT administration in IBD remains unexplored, and future investigations are essential.

Exclusive Enteral Nutrition Induces Remission in Pediatric Crohn's Disease via Modulation of the Gut Microbiota

Exclusive enteral nutrition (EEN) has been proven to be effective and safe in treating pediatric Crohn's disease (CD). EEN induces pediatric CD remission possibly through three pathways: (1) direct anti-inflammatory effects, (2) improved epithelial barrier function, and (3) modulation of the gut microbiota. Recent studies have demonstrated that modulation of the gut microbiota plays a major role in EEN-induced remission. Variations of microbial components, which directly influence the diversity and metabolic functions of the gut microbiota, are closely associated with the immunological conditions of the gut and the susceptibility to diseases. The reduction of proinflammatory microbial components and harmful microbial metabolites after EEN treatment greatly decreases the inflammatory injuries of the gut.

Effects of the Exclusive Enteral Nutrition on the Microbiota Profile of Patients with Crohn's Disease: A Systematic Review

The mechanisms behind the efficacy of exclusive enteral nutrition (EEN) in Crohn's disease (CD) remain poorly understood, despite the high rate of treatment response. Evidence accumulated in the last 20 years suggests that a positive shift of the disrupted microbiota is one of the treatment effects. The purpose of this study was to critically review and summarize data reporting the microbiological effects of EEN in patients with CD. Fourteen studies were considered in the review, overall involving 216 CD patients on EEN. The studies were heterogeneous in methods of microbiota analysis and exclusion criteria. The most frequently reported effect of EEN was a reduction in microbiota diversity, reversible when patients returned to a normal diet. The effect of EEN on specific bacteria was very variable in the different studies, partially due to methodological limitations of the mentioned studies. The EEN seem to induce some metabolomic changes, which are different in long-term responder patients compared to patients that relapse earlier. Bacterial changes can be relevant to explaining the efficacy of EEN; however, microbiological data obtained from rigorously performed studies and derived from last generation techniques are largely inconsistent.

The Impact of Exclusive Enteral Nutrition (EEN) on the Gut Microbiome in Crohn's Disease: A Review

Crohn’s disease (CD), a form of inflammatory bowel disease (IBD), is thought to arise from a complex interaction of genetics, the gut microbiome, and environmental factors, such as diet. There is clear evidence that dietary intervention is successful in the treatment of CD—exclusive enteral nutrition (EEN) is able to induce remission in up to 80% of CD patients. While the mechanism of action of EEN is not clear, EEN is known to cause profound changes in the gut microbiome. Understanding how EEN modifies the gut microbiome to induce remission could provide insight into CD etiopathogenesis and aid the development of microbiome-targeted interventions to guide ongoing dietary therapy to sustain remission. This review includes current literature on changes in composition and function of the gut microbiome associated with EEN treatment in CD patients.

Towards an integrated understanding of the therapeutic utility of exclusive enteral nutrition in the treatment of Crohn's disease

Crohn's disease (CD) is a chronic disease characterized by episodic and disabling inflammation of the gastrointestinal tract in genetically susceptible individuals. The incidence and prevalence of CD is rising rapidly across the world emphasising that disease risk is also influenced by environmental and lifestyle factors, as well as the microbial community resident in the gut. Childhood-onset CD is associated with an aggressive disease course that can adversely impact patient growth and development. There is no cure for CD however new onset and recurrent cases of paediatric CD are often responsive to exclusive enteral nutrition (EEN) treatment. EEN treatment involves the exclusive consumption of an elemental or polymeric formula for several weeks and it is well established as a primary intervention strategy. EEN treatments typically achieve remission rates of over 80% and importantly they are associated with a high rate of mucosal healing, far superior to steroids, which is prognostic of improved long-term health outcomes. Furthermore, they are safe, have few side effects, and improve nutritional status and linear growth. Surprisingly, despite the utility of EEN our understanding of the host-microbe-diet interactions that underpin clinical remission and mucosal healing are limited. Here, we review the current state of knowledge and propose that the induction of autophagy, in addition to modulation of the microbiota and coordinated effects on inflammation and epithelial cell biology, may be critical for the therapeutic effects associated with EEN. A better understanding of EEN treatment will provide new opportunities to restore gut homeostasis and prolong periods of remission, as well as provide new insights into the factors that trigger and perhaps prevent CD.

Early Changes in Microbial Community Structure Are Associated with Sustained Remission After Nutritional Treatment of Pediatric Crohn's Disease

BACKGROUND

Clinical remission achieved by exclusive enteral nutrition (EEN) is associated with marked microbiome changes. In this prospective study of exclusive enteral nutrition, we employ a hierarchical model of microbial community structure to distinguish between pediatric Crohn's disease patients who achieved sustained remission (SR) and those who relapsed early (non-SR), after restarting a normal diet.

METHODS

Fecal samples were obtained from 10 patients (age 10-16) and from 5 healthy controls (age 9-14). The microbiota was assessed via 16S rRNA sequencing. In addition to standard measures of microbial biodiversity, we employed Bayesian methods to characterize the hierarchical community structure. Community structure between patients who sustained remission (wPCDAI <12.5) up to their 24-week follow-up (SR) was compared with patients that had not sustained remission (non-SR).

RESULTS

Microbial diversity was lower in Crohn's disease patients relative to controls and lowest in patients who did not achieve SR. SR patients differed from non-SR patients in terms of the structure and prevalence of their microbial communities. The SR prevalent community contained a number of strains of Akkermansia muciniphila and Bacteroides and was limited in Proteobacteria, whereas the non-SR prevalent community had a large Proteobacteria component. Their communities were so different that a model trained to discriminate SR and non-SR had 80% classification accuracy, already at baseline sampling.

CONCLUSIONS

Microbial community structure differs between healthy controls, patients who have an enduring response to exclusive enteral nutrition, and those who relapse early on introduction of normal diet. Our novel Bayesian approach to these differences is able to predict sustained remission after exclusive enteral nutrition.

The Gut Microbiome of Pediatric Crohn's Disease Patients Differs from Healthy Controls in Genes That Can Influence the Balance Between a Healthy and Dysregulated Immune Response

BACKGROUND

Exclusive enteral nutrition (EEN) is a first-line therapy in pediatric Crohn's disease (CD) thought to induce remission through changes in the gut microbiome. With microbiome assessment largely focused on microbial taxonomy and diversity, it remains unclear to what extent EEN induces functional changes that thereby contribute to its therapeutic effect.

METHODS

Fecal samples were collected from 15 pediatric CD patients prior to and after EEN treatment, as well as from 5 healthy controls. Metagenomic data were obtained via next-generation sequencing, and nonhuman reads were mapped to KEGG pathways, where possible. Pathway abundance was compared between CD patients and controls, and between CD patients that sustained remission (SR) and those that did not sustain remission (NSR).

RESULTS

Of 132 KEGG pathways identified, 8 pathways differed significantly between baseline CD patients and controls. Examination of these eight pathways showed SR patients had greater similarity to controls than NSR patients in all cases. Pathways fell into one of three groups: 1) no prior connection to IBD, 2) previously reported connection to IBD, and 3) known roles in innate immunity and immunoregulation.

CONCLUSIONS

The microbiota of CD patients and controls represent alternative ecological states that have broad differences in functional capabilities, including xenobiotic and environmental pollutant degradation, succinate metavolism, and bacterial HtpG, all of which can affect barrier integrity and immune regulation. Moreover, our finding that SR patients were more similar to healthy controls suggests that community microbial function, as inferred from fecal microbiomes, could serve as a valuable diagnostic tool.

Bacterial nutrient foraging in a mouse model of enteral nutrient deprivation: insight into the gut origin of sepsis

Total parenteral nutrition (TPN) leads to a shift in small intestinal microbiota with a characteristic dominance of Proteobacteria This study examined how metabolomic changes within the small bowel support an altered microbial community in enterally deprived mice. C57BL/6 mice were given TPN or enteral chow. Metabolomic analysis of jejunal contents was performed by liquid chromatography/mass spectrometry (LC/MS). In some experiments, leucine in TPN was partly substituted with [¹³C]leucine. Additionally, jejunal contents from TPN-dependent and enterally fed mice were gavaged into germ-free mice to reveal whether the TPN phenotype was transferrable. Small bowel contents of TPN mice maintained an amino acid composition similar to that of the TPN solution. Mass spectrometry analysis of small bowel contents of TPN-dependent mice showed increased concentration of ¹³C compared with fed mice receiving saline enriched with [¹³C]leucine. [¹³C]leucine added to the serosal side of Ussing chambers showed rapid permeation across TPN-dependent jejunum, suggesting increased transmucosal passage. Single-cell analysis by fluorescence in situ hybridization (FISH)-NanoSIMS demonstrated uptake of [¹³C]leucine by TPN-associated bacteria, with preferential uptake by Enterobacteriaceae Gavage of small bowel effluent from TPN mice into germ-free, fed mice resulted in a trend toward the proinflammatory TPN phenotype with loss of epithelial barrier function. TPN dependence leads to increased permeation of TPN-derived nutrients into the small intestinal lumen, where they are predominately utilized by Enterobacteriaceae The altered metabolomic composition of the intestinal lumen during TPN promotes dysbiosis.

Enteral feeding reduces metabolic activity of the intestinal microbiome in Crohn's disease: an observational study

BACKGROUND/OBJECTIVES

Enteral feeding will induce remission in as many as 80-90% of compliant patients with active Crohn's disease (CD), but its method of action remains uncertain. This study was designed to examine its effects on the colonic microbiome.

METHODS/SUBJECTS

Healthy volunteers and patients with CD followed a regimen confined to enteral feeds alone for 1 or 2 weeks, respectively. Chemicals excreted on breath or in faeces were characterised at the start and at the end of the feeding period by gas chromatography/mass spectrometry.

RESULTS

One week of feeding in healthy volunteers caused significant changes in stool colour and deterioration in breath odour, together with increased excretion of phenol and indoles on the breath. Feeding for 2 weeks in patients with CD produced significant improvements in symptoms and a decrease in the concentration of C-reactive protein. The faecal concentrations of microbial products, including short-chain fatty acids (SCFAs), and potentially toxic substances, including 1-propanol, 1-butanol and the methyl and ethyl esters of SCFAs, showed significant falls.

CONCLUSIONS

A significant change occurs in the production of microbial metabolites after enteral feeding in both healthy volunteers and patients with CD. Many of those detected in CD are toxic and may feasibly lead to the immunological attack on the gut microbiota, which is characteristic of inflammatory bowel disease. The reduction in the production of such metabolites after enteral feeding may be the reason for its effectiveness in CD.

Membrane filter method to study the effects of Lactobacillus acidophilus and Bifidobacterium longum on fecal microbiota

A large number of commensal bacteria inhabit the intestinal tract, and interbacterial communication among gut microbiota is thought to occur. In order to analyze symbiotic relationships between probiotic strains and the gut microbiota, a ring with a membrane filter fitted to the bottom was used for in vitro investigations. Test strains comprising probiotic nitto strains (Lactobacillus acidophilus NT and Bifidobacterium longum NT) and type strains (L. acidophilus JCM1132^T and B. longum JCM1217^T) were obtained from diluted fecal samples using the membrane filter to simulate interbacterial communication. Bifidobacterium spp., Streptococcus pasteurianus, Collinsella aerofaciens, and Clostridium spp. were the most abundant gut bacteria detected before coculture with the test strains. Results of the coculture experiments indicated that the test strains significantly promote the growth of Ruminococcus gnavus, Ruminococcus torques, and Veillonella spp. and inhibit the growth of Sutterella wadsworthensis. Differences in the relative abundances of gut bacterial strains were furthermore observed after coculture of the fecal samples with each test strain. Bifidobacterium spp., which was detected as the dominant strain in the fecal samples, was found to be unaffected by coculture with the test strains. In the present study, interbacterial communication using bacterial metabolites between the test strains and the gut microbiota was demonstrated by the coculture technique. The detailed mechanisms and effects of the complex interbacterial communications that occur among the gut microbiota are, however, still unclear. Further investigation of these relationships by coculture of several fecal samples with probiotic strains is urgently required.

The Efficacy of an Oral Elemental Diet in Patients Undergoing Hematopoietic Stem Cell Transplantation

Objective Conditioning regimens for hematopoietic stem cell transplantation (HSCT) are well known to cause severe gastrointestinal toxicities that often disturb the oral intake of the patients followed by poor nutrition and life-threatening infection. An oral elemental diet (ED) is an easily consumed and assimilated form of liquid nutrients mainly composed of amino acids. It alleviates the digestive loading from the intestine and is mainly used for enteral nutritional support in patients with Crohn's disease. We herein report, for the first time, the efficacy of ED for patients undergoing HSCT. Methods We evaluated the efficacy of ED in a prospective cohort study. The primary endpoint for this study was the hospitalization period. The secondary endpoint was the occurrence of oral mucositis, nausea, diarrhea and fever. Patients A total of 73 patients were consecutively enrolled between March 2011 and March 2013. Twenty-three patients underwent autologous HSCT and 50 patients underwent allogeneic HSCT. The first 21 patients did not receive ED (non-ED group; NEG) while in the successive 52 patients (ED group; EG), oral ED was started before conditioning and was continued until 28 days after transplantation. Results The patient characteristics were similar between the two groups. The mean duration of ED administration for EG was 28.7 days (range, 3-37 days), and the mean total-dose of ED administration was 1904 g (range, 240-2,960 g). The median hospitalization period was significantly shorter in EG compared to NEG, (34 days vs. 50 days; p=0.007). Grade 3-4 oral mucositis occurred less in EG than NEG (25% vs. 48%; p=0.06). Conclusion Oral ED may promote an early mucosal recovery and thereby shorten the duration of hospitalization.

Changes to the Intestinal Microbiome With Parenteral Nutrition: Review of a Murine Model and Potential Clinical Implications

Parenteral nutrition (PN) dependence, while life sustaining, carries a significant risk of septic complications associated with epithelial barrier dysfunction and translocation of gut-derived microbiota. Increasing evidence suggests that PN-associated changes in the intestinal microbiota play a central role in the breakdown of the intestinal epithelial barrier. This review outlines the clinical and experimental evidence of epithelial barrier dysfunction with PN, the role of gut inflammatory dysregulation in driving this process, and the role of the intestinal microbiome in modulating inflammation in the gut and systemically. The article summarizes the most current work of our laboratory and others and describes many of the laboratory findings behind our current understanding of the PN enteral environment. Understanding the interaction between nutrient delivery, the intestinal microbiome, and PN-associated complications may lead to the development of novel therapies to enhance safety and quality of life for patients requiring PN.

Surface-Associated Lipoproteins Link Enterococcus faecalis Virulence to Colitogenic Activity in IL-10-Deficient Mice Independent of Their Expression Levels

The commensal Enterococcus faecalis is among the most common causes of nosocomial infections. Recent findings regarding increased abundance of enterococci in the intestinal microbiota of patients with inflammatory bowel diseases and induction of colitis in IL-10-deficient (IL-10-/-) mice put a new perspective on the contribution of E. faecalis to chronic intestinal inflammation. Based on the expression of virulence-related genes in the inflammatory milieu of IL-10-/- mice using RNA-sequencing analysis, we characterized the colitogenic role of two bacterial structures that substantially impact on E. faecalis virulence by different mechanisms: the enterococcal polysaccharide antigen and cell surface-associated lipoproteins. Germ-free wild type and IL-10-/- mice were monoassociated with E. faecalis wild type OG1RF or the respective isogenic mutants for 16 weeks. Intestinal tissue and mesenteric lymph nodes (MLN) were collected to characterize tissue pathology, loss of intestinal barrier function, bacterial adhesion to intestinal epithelium and immune cell activation. Bone marrow-derived dendritic cells (BMDC) were stimulated with bacterial lysates and E. faecalis virulence was additionally investigated in three invertebrate models. Colitogenic activity of wild type E. faecalis (OG1RF score: 7.2±1.2) in monoassociated IL-10-/- mice was partially impaired in E. faecalis lacking enterococcal polysaccharide antigen (ΔepaB score: 4.7±2.3; p<0.05) and was almost completely abrogated in E. faecalis deficient for lipoproteins (Δlgt score: 2.3±2.3; p<0.0001). Consistently both E. faecalis mutants showed significantly impaired virulence in Galleria mellonella and Caenorhabditis elegans. Loss of E-cadherin in the epithelium was shown for all bacterial strains in inflamed IL-10-/- but not wild type mice. Inactivation of epaB in E. faecalis reduced microcolony and biofilm formation in vitro, altered bacterial adhesion to intestinal epithelium of germ-free Manduca sexta larvae and impaired penetration into the colonic mucus layer of IL-10-/- mice. Lipoprotein-deficient E. faecalis exhibited an impaired TLR2-mediated activation of BMDCs in vitro despite their ability to fully reactivate MLN cells as well as MLN-derived colitogenic T cells ex vivo. E. faecalis virulence factors accounting for bacterial adhesion to mucosal surfaces as well as intestinal barrier disruption partially contribute to colitogenic activity of E. faecalis. Beyond their well-known role in infections, cell surface-associated lipoproteins are essential structures for colitogenic activity of E. faecalis by mediating innate immune cell activation.

Enterococcus faecalis is a commensal of the human intestinal core microbiota harboring several putative virulence factors, which highlight its role as opportunistic pathogen. This dualistic character is supported by recent evidence linking Enterococcus spp. to the pathogenesis of inflammatory bowel diseases (IBD). Although several studies suggest a crucial role for opportunistic pathogens in IBD pathogenesis targeting genetically susceptible individuals, the dynamic relationship between disease-relevant host compartments and specific bacterial structures able to trigger intestinal inflammation remain unclear. Here, we report that cell surface-associated lipoproteins and the enterococcal polysaccharide antigen, which are relevant for E. faecalis virulence in invertebrate infection models, but whose expression is minimally affected by the intestinal inflammatory milieu, exhibit colitogenic activity in a mouse model susceptible for chronic colitis. Bacterial lipoproteins trigger innate immune cell activation and are a critical prerequisite for E. faecalis-induced colitis. The enterococcal polysaccharide antigen mediates bacterial mucus penetration and adhesion to mucosal surfaces, promotes the formation of biofilm and contributes to E. faecalis colitogenic activity. Using E. faecalis as a model organism, we demonstrate that colitogenic activity of opportunistic pathogens can be assigned to specific bacterial structures, a finding that may help to identify the most essential steps in IBD-related microbe-host interactions.

Can inflammatory bowel disease be permanently treated with short-term interventions on the microbiome?

Inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis, is a chronic, relapsing and remitting set of conditions characterized by an excessive inflammatory response leading to the destruction of the gastrointestinal tract. While the exact etiology of inflammatory bowel disease remains unclear, increasing evidence suggests that the human gastrointestinal microbiome plays a critical role in disease pathogenesis. Manipulation of the gut microbiome has therefore emerged as an attractive alternative for both prophylactic and therapeutic intervention against inflammation. Despite its growing popularity among patients, review of the current literature suggests that the adult microbiome is a highly stable structure resilient to short-term interventions. In fact, most evidence to date demonstrates that therapeutic agents targeting the microflora trigger rapid changes in the microbiome, which then reverts to its pre-treatment state once the therapy is completed. Based on these findings, our ability to treat inflammatory bowel disease through short-term manipulations of the human microbiome may only have a transient effect. Thus, this review is intended to highlight the use of various therapeutic options, including diet, pre- and probiotics, antibiotics and fecal microbiota transplant, to manipulate the microbiome, with specific attention to the alterations made to the microflora along with the duration of impact.

An integrative view of microbiome-host interactions in inflammatory bowel diseases

The intestinal microbiota, which is composed of bacteria, viruses, and micro-eukaryotes, acts as an accessory organ system with distinct functions along the intestinal tract that are critical for health. This review focuses on how the microbiota drives intestinal disease through alterations in microbial community architecture, disruption of the mucosal barrier, modulation of innate and adaptive immunity, and dysfunction of the enteric nervous system. Inflammatory bowel disease is used as a model system to understand these microbial-driven pathologies, but the knowledge gained in this space is extended to less-well-studied intestinal diseases that may also have an important microbial component, including environmental enteropathy and chronic colitis-associated colorectal cancer.

Effect of exclusive enteral nutrition on the microbiota of children with newly diagnosed Crohn's disease

OBJECTIVES

Exclusive enteral nutrition (EEN) is commonly used to treat pediatric Crohn's disease (CD). Meta-analysis of pediatric studies that have compared the effect of EEN with other treatments have shown that EEN induces remission in up to 80-85% of patients. We aimed to gain a comprehensive understanding of the effect of EEN on the microbiota of CD patients.

METHODS

We used 16S rRNA gene and whole-genome high throughout sequencing to determine changes in the fecal microbiota of five CD children, before, during, and after EEN therapy and compared this with five healthy controls.

RESULTS

The microbial diversity observed in CD patients tended to be lower than that in controls (CD: 2.25±0.24, controls: 2.75±0.14, P=0.11). In all CD patients, dysbiosis was observed prior to therapy. EEN therapy had a positive effect in all patients, with 80% going into remission. In some patients, the positive effect diminished following the conclusion of EEN therapy. Significantly, the number of operational taxonomic units (OTU) decreased dramatically upon starting EEN and this corresponded with CD remission. Recurrence of CD corresponded with an increase in OTUs. Six families within the Firmicutes were found to correlate with disease activity during and following EEN therapy, a finding that was confirmed by whole-genome high throughput sequencing.

CONCLUSIONS

Our results demonstrate that EEN leads to common and patient-specific alterations in the microbiota of CD patients, a number of which correlate with disease activity.

Clinical and mucosal improvement with specific carbohydrate diet in pediatric Crohn disease

OBJECTIVE

The aim of the study was to prospectively evaluate clinical and mucosal responses to the specific carbohydrate diet (SCD) in children with Crohn disease (CD).

METHODS

Eligible patients with active CD (Pediatric Crohn's Disease Activity Index [PCDAI] ≥ 15) underwent a patency capsule and, if passed intact, capsule endoscopy (CE) was performed. Patients taking SCD were monitored for 52 weeks while maintaining all prescribed medications. Demographic, dietary, and clinical information, PCDAI, Harvey-Bradshaw Index (HBI), and Lewis score (LS) were collected at 0, 12, and 52 weeks. CEs were evaluated by an experienced reader blinded to patient clinical information and timing.

RESULTS

Sixteen patients were screened; 10 enrolled; and 9 completed the initial 12-week trial-receiving 85% of estimated caloric needs before, and 101% on the SCD. HB significantly decreased from 3.3 ± 2.0 to 0.6 ± 1.3 (P = 0.007) as did PCDAI (21.1 ± 5.9 to 7.8 ± 7.1, P = 0.011). LS declined significantly from 2153 ± 732 to 960  ± 433 (P = 0.012). Seven patients continued the SCD up to 52 weeks; HB (0.1 ± 0.4) and PCDAI (5.4 ± 5.5) remained improved (P = 0.016 and 0.027 compared to baseline), with mean LS at 1046 ± 372 and 2 patients showed sustained mucosal healing.

CONCLUSIONS

Clinical and mucosal improvements were seen in children with CD, who used SCD for 12 and 52 weeks. In addition, CE can monitor mucosal improvement in treatment trials for pediatric CD. Further studies are critically needed to understand the mechanisms underlying SCD's effectiveness in children with CD.

Decline in presumptively protective gut bacterial species and metabolites are paradoxically associated with disease improvement in pediatric Crohn's disease during enteral nutrition

BACKGROUND

The gut microbiota is implicated in the pathogenesis of Crohn's disease (CD). Exclusive enteral nutrition (EEN) is a successful treatment, but its mode of action remains unknown. This study assessed serial changes in the fecal microbiota milieu during EEN.

METHODS

Five fecal samples were collected from CD children: 4 during EEN (start, 15, 30, end EEN approximately 60 days) and the fifth on habitual diet. Two samples were collected from healthy control subjects. Fecal pH, bacterial metabolites, global microbial diversity abundance, composition stability, and quantitative changes of total and 7 major bacterial groups previously implicated in CD were measured.

RESULTS

Overall, 68 samples were from 15 CD children and 40 from 21 control subjects. Fecal pH and total sulfide increased and butyric acid decreased during EEN (all P < 0.05). Global bacterial diversity abundance decreased (P < 0.05); a higher degree of microbiota composition stability was seen in control subjects than in CD children during EEN (at P ≤ 0.008). Faecalibacterium prausnitzii spp concentration significantly decreased after 30 days on EEN (P < 0.05). In patients who responded to EEN, the magnitude of the observed changes was greater and the concentration of Bacteroides/Prevotella group decreased (P < 0.05). All these changes reverted to pretreatment levels on free diet, and EEN microbiota diversity increased when the children returned to their free diet.

CONCLUSIONS

EEN impacts on gut microbiota composition and changes fecal metabolic activity. It is difficult to infer a causative association between such changes and disease improvement, but the results do challenge the current perception of a protective role for F. prausnitzii in CD.