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Prebiotics and human milk oligosaccharides modulate the gut microbiota, decrease bacterial adherence and may directly alter the host immune system to confer health benefits on the host. In particular, human milk oligosaccharides have received significant interest as they reduce inflammation in models of infectious colitis and necrotizing enterocolitis. Yet, their mechanisms of action remain largely unknown. There are more than 150 oligosaccharide structures identified thus far, but the specific structures and function relevant in specific disease states are still unclear. This article reviews current understanding of prebiotics and human milk oligosaccharides.

Objective: Despite a substantial consistency in recommendations for the management of children with acute gastroenteritis (AGE), a high variability in clinical practice and a high rate of inappropriate medical interventions persist in both developing and developed countries. The aim of this study was to develop a set of clinical recommendations for the management of nonseverely malnourished children with AGE to be applied worldwide. Methods: The Federation of International Societies of Pediatric Gastroenterology, Hepatology, and Nutrition (FISPGHAN) Working Group (WG) selected care protocols on the management of acute diarrhea in infants and children aged between 1 month and 18 years. The WG used a 3-step approach consisting of: systematic review and comparison of published guidelines, agreement on draft recommendations using Delphi methodology, and external peer-review and validation of recommendations. Results: A core of recommendations including definition, diagnosis, nutritional management, and active treatment of AGE was developed with an overall agreement of 91% (range 80%–96%). A total of 28 world experts in pediatric gastroenterology and emergency medicine successively validated the set of 23 recommendations with an agreement of 87% (range 83%–95%). Recommendations on the use of antidiarrheal drugs and antiemetics received the lowest level of agreement and need to be tailored at local level. Oral rehydration and probiotics were the only treatments recommended. Conclusions: Universal recommendations to assist health care practitioners in managing children with AGE may improve practitioners’ compliance with guidelines, reduce inappropriate interventions, and significantly impact clinical outcome and health care-associated costs.

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency affecting preterm infants. Breastmilk protects against NEC, partly due to human milk oligosaccharides (HMOs). HMO compositions are highly diverse, and it is unclear if anti-NEC properties are specific to carbohydrate motifs. Here, this study compares intestinal epithelial transcriptomes of five synthetic HMOs (sHMOs) and examines structure-function relationships of HMOs on intestinal signaling.This study interrogates the transcriptome of Caco-2Bbe1 cells in response to five synthetic HMOs (sHMOs) using RNA sequencing: 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3FL), 6'-siallyllactose (6'-SL), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT). Protection against intestinal barrier dysfunction and inflammation occurred in an HMO-dependent manner. Each sHMO exerts a unique set of host transcriptome changes and modulated unique signaling pathways. There is clustering between HMOs bearing similar side chains, with little overlap in gene regulation which is shared by all sHMOs. Interestingly, most sHMOs protect pups against NEC, exerting divergent mechanisms on intestinal cell morphology and inflammation.These results demonstrate that while structurally distinct HMOs impact intestinal physiology, their mechanisms of action differ. This finding establishes the first structure-function relationship of HMOs in the context of intestinal cell signaling responses and offers a functional framework by which to screen and design HMO-like compounds.

Background Colorectal cancer (CRC) is the third leading cause of cancer death, with a major risk factor being chronic inflammation. Thus, patients with inflammatory bowel disease (IBD) are at an increased risk of CRC. Despite the clear association between inflammation and cancer, the mechanism by which colitis leads to CRC is still not well understood. Aims In this study, we aim to explore the mechanism by which inflammation contributes to the initiation of colitis-associated cancer (CAC). We hypothesize that dextran sodium sulfate (DSS)-induced colitis leads to the infiltration of a specific immune cell type associated with tumorigenesis. Methods Following an injection of azoxymethane (AOM), mice were treated with the colitis-inducing agents DSS, trinitrobenzene sulfonic acid (TNBS), oxazolone (oxa), Citrobacter rodentium, or Doxorubicin (Doxo). The tumor studies were repeated using our published Cre-dependent murine model of CAC. To generate tamoxifen-inducible Cre transgenic mice that allow for Dclk1+ cell lineage tracing and cell-specific knock-out of the tumor suppressor adenomatous polyposis coli (APC), we crossed our Dclk1CreERT2 mice to both ROSA26tdTomato and APCfl/fl mice (Dclk1/APCfl/fl). Results Treatment with DSS, TNBS, oxa, C. rodentium, or Doxo induced colonic inflammation as detected by increased myeloperoxidase (MPO) activity and histologic analysis. DSS administration led to colonic tumors, whereas TNBS, oxa, C. rodentium, or Doxo did not lead to tumorigenesis up to 52 weeks following colitis induction. Upon flow cytometric analysis of several types of immune cells in the colonic tissue, we observed no difference in the number of T and B cells between mice treated with various colitis inducing agents. We did, however, detect significantly increased levels of Ly6G+ neutrophils and F4/80+Ly6Chi macrophages in the DSS-treated mice when compared to mice in the other models of colitis. mRNA and protein array analyses of the colonic tissue, as well as analysis of the RNA-seq data from 206 UC patients (GSE109142), revealed upregulated expression of genes associated with macrophages and neutrophils. Addition of macrophage-produced cytokines, such as IL-1β, TNF-α, or IL-6, induced lineage tracing of Dclk1+ tuft cells in intestinal organoids. Clodronate liposome-mediated depletion of F4/80+Ly6Chi macrophages significantly reduced the number of colonic tumors but did not affect tumor size in Dclk1/APCfl/fl mice. Conclusions Our data suggest that infiltration of F4/80+Ly6Chi macrophages, unique to DSS-induced colitis, leads to colonic tumor formation. This demonstrates that specific immune cell types, rather than the presence of colonic inflammation, plays an important role in the initiation of CAC. Funding Agencies CAG, CIHR

Background Necrotizing enterocolitis (NEC) causes severe gastrointestinal disease in premature infants. A precise etiology is not yet known, but it is generally agreed that intestinal immaturity & alterations in the gut microbiota play key roles in NEC progression. There is growing interest in the clinical use of probiotics for the prevention of NEC in at-risk infants. Some probiotics, which are defined as beneficial bioactive microbes that provide a health benefit when administered in sufficient amounts, may influence disease outcome in premature infants with NEC. Aims To investigate the efficacy of two commercially available probiotic formulations, Lacidofil® and ProBiokid®, in the prevention of experimentally-induced NEC. Methods At gestational day 12.5, treated dams were administered probiotics (109 cfu/mL) in drinking water (Table 1). NEC was induced at postnatal day 5 or when pups were ≥ 3.0 g by the administration of hyperosmolar formula, hypoxia, and lipopolysaccharide (4 mg/kg). NEC pups receiving probiotics were administered 108cfu in hyperosmolar formula once daily during the morning feeding. Body weight, survival and disease severity were scored. Results Neither probiotic intervention affected overall survival of NEC-induced pups. Control dam-fed pups (NN) continued to gain weight as expected over time, while untreated NEC pups (NNNEC) exhibited a significant delay in weight gain. LLNEC pups exhibited the greatest percent body weight increase over time, possibly due to a lower birth weight. Lacidofil administration did not improve NEC-induced tissue damage irrespective of the timing of intervention. In contrast, Probiokid provided to both dam and pups (PPNEC) resulted in less severe tissue damage compared to their control counterparts. Conclusions These finding demonstrate strain-specific differences in two different commercial probiotic formulations in the prevention of NEC in newborn mice. Future studies seek to provide insight into how Lacidofil and Probiokid engage intestinal stem cells (Lgr5-GFP mice), cell proliferation (Ki67 positivity) and differentiation (MUC2 & Chromogranin A positivity) in the NEC-damaged intestine. Funding Agencies CIHRMITACS Accelerate Postdoctoral Award

Introduction Necrotizing enterocolitis (NEC) is a devastating intestinal illness in premature infants characterized by severe intestinal inflammation. Despite medical interventions, NEC mortality remains alarmingly high, which necessitates improved therapies. Lactoferrin is among the most abundant proteins in human milk and has important immunomodulatory functions. While previous studies have indicated protective effects of lactoferrin against neonatal sepsis and NEC, the underlying mechanism remains unclear. We hypothesize that lactoferrin downregulates inflammation and upregulates proliferation in intestinal epithelium during NEC injury. Materials and Methods NEC was induced by hypoxia, gavage feeding of hyperosmolar formula and lipopolysaccharide between postnatal day P5 and P9 (n = 8). Breastfed mice were used as control (n = 7). Lactoferrin (0.3 g/kg/day) was administered once daily by gavage from P6 to P8 in both NEC (NEC + Lac; n = 9) and control mice (Cont + Lac; n = 5). Distal ileum was harvested on P9 and analyzed for disease severity, inflammation, and proliferation. Groups were compared using one-way ANOVA and t-test appropriately; p Results Compared to NEC group, lactoferrin-treated NEC mice had reduced disease severity, reduced inflammation markers IL-6 and TNF-α expression and increased intestinal stem cell marker Lgr5 + expression. Lactoferrin-treated NEC mice exhibited increased nuclear β-catenin, indicating upregulated Wnt pathway, and increased Ki67 positivity, suggesting enhanced proliferation. Furthermore, lactoferrin administration to control mice did not affect intestinal inflammation as well as Lgr5 + stem cell expression and epithelial proliferation. This supports the safety of lactoferrin administration and indicates that the beneficial effects of lactoferrin are present when intestinal injury such as NEC is present. Conclusion Lactoferrin administration reduces the intestinal injury in experimental NEC by downregulating inflammation and upregulating cell proliferation. This beneficial effect of lactoferrin in stimulating cell proliferation is mediated by the Wnt pathway. This experimental study provides insights on the mechanism of action of lactoferrin in NEC and the role of lactoferrin in enteral feeding.

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer death in Canada, with the major risk factor being chronic inflammation. As such, patients with inflammatory bowel disease (IBD) are at an increased risk of CRC. Despite the clear association between inflammation and cancer, the mechanism by which colitis leads to CRC is still not well understood. Our recent work has focused on a colonic epithelial cell known as the tuft cell that uniquely expresses the protein doublecortin-like kinase 1 (Dclk1). Using Cre-dependent lineage tracing of Dclk1-expressing cells, we showed that Dclk1 labels long-lived quiescent cells in the colon that serve as a cellular origin of CRC upon colonic inflammation. AIMS: In this study, we aim to explore the mechanism by which inflammation contributes to tuft cell cancer initiation. We hypothesized that colonic inflammatory insult leads to dedifferentiation of Dclk1+ tuft cells to a stem cell state susceptible to tumor initiation. METHODS: To generate tamoxifen-inducible Cre transgenic mice that allow for Dclk1(+) cell lineage tracing and cell-specific knock-out of the tumor suppressor adenomatous polyposis coli (APC), we first crossed our transgenic Dclk1-CreER(T2) mice to both ROSA26-tdTomato and APC(fl/fl) mice (Dclk1/APC(fl/fl)). To examine the role of dedifferentiation in colonic tumor initiation, these mice were further crossed to Lgr5-DTR-eGFP mice (Lgr5(DTR);Dclk1/APC(fl/fl)). These mice were given tamoxifen and DSS in order to induce tumorigenesis. Mice were administered diphtheria toxin (DT) for six weeks post DSS injury to ablate Lgr5-expressing cells and were compared to Lgr5(DTR)-negative control mice (Dclk1/APC(fl/fl)). RESULTS: Reverse transcription polymerase chain reaction (RT-PCR) analysis of mRNA levels revealed significantly reduced Lgr5, and increased RSPO1 and RSPO3 levels in colonic tissues of DSS-administered mice. Ablation of Lgr5(+) cells post DSS-colitis significantly reduced the number of colonic tumors in our Dclk1/APC(fl/fl) mouse model, with no significant difference in tumor size. Lgr5-expressing cells were readily seen throughout colonic tumors arising from Dclk1(+) cells. Interestingly, two weeks post DSS-induced colitis, rare Dclk1(+) cells that co-expressed Lgr5 were also detected. CONCLUSIONS: Our data prove that upon DSS-induced colonic injury, Dclk1(+) tuft cells express the stem cell marker Lgr5 prior to initiation of colonic tumorigenesis. These data suggest that dedifferentiation of Dclk1(+) cells plays an important role in colitis-associated CRC and provide insight into the molecular mechanism by which Dclk1-derived colonic tumors arise. FUNDING AGENCIES: CAG, CIHRCRS

Necrotizing enterocolitis (NEC) is characterized by intestinal injury and impaired mucin synthesis. We recently showed that breast milk exosomes from rodents promote intestinal cell viability, epithelial proliferation, and stem cell activity, but whether they also affect mucus production is unknown. Therefore, the aim of this study was to investigate the effects of bovine milk-derived exosomes on goblet cell expression in experimental NEC and delineate potential underlying mechanisms of action. Exosomes were isolated from bovine milk by ultracentrifugation and confirmed by Nanoparticle Tracking Analysis and through the detection of exosome membrane markers. To study the effect on mucin production, human colonic LS174T cells were cultured and exposed to exosomes. Compared to control, exosomes promoted goblet cell expression, as demonstrated by increased mucin production and relative expression levels of goblet cell expression markers trefoil factor 3 (TFF3) and mucin 2 (MUC2). In addition, exosome treatment enhanced the expression of glucose-regulated protein 94 (GRP94), the most abundant intraluminal endoplasmic reticulum (ER) chaperone protein that aids in protein synthesis. Furthermore, experimental NEC was induced in mouse pups by hyperosmolar formula feeding, lipopolysaccharide administration and hypoxia exposure on postnatal days 5-9. Milk exosomes were given with each gavage feed. NEC was associated with ileal morphological injury and reduction in MUC2+ goblet cells and GRP94+ cells per villus. Exosome administration to NEC pups prevented these changes. This research highlights the potential novel application of milk-derived exosomes in preventing the development of NEC in high-risk infants when breast milk is not available.

Background: Bacteriotherapy and modulation of intestinal microbiome by administering probiotics, prebiotics, or both have long been suggested to prevent morbidity and mortality in premature infants. Our objective was to assess the comparative effectiveness of different prophylactic strategies in a network meta-analysis (NMA) of randomized trials. Methods: We searched MEDLINE, EMBASE, Science Citation Index Expanded, CINAHL, Scopus, Cochrane Central, BIOSIS Previews, and Google Scholar from inception up until December 1, 2018· All-cause mortality, severe necrotizing enterocolitis (NEC - Bell stage II or more), and culture proven sepsis were our a priori primary outcomes. We used a frequentist approach for NMA and assessed the certainty of evidence using the GRADE approach. Findings: We included 79 trials involving 17,655 preterm infants. Multiple-strain probiotics alone proved the only intervention with moderate- or high-quality evidence of reduced all-cause mortality relative to placebo (OR = 0·67; 95% CI: 0·52, 0·87; high certainty; absolute risk reduction = 1·5%). Compared to placebo, multiple-strain probiotics (OR = 0·35; 95% CI: 0·26, 0·47; moderate certainty; absolute risk reduction = 4·1%), and single-strain probiotics alone (OR = 0·63; 95% CI: 0·46, 0·86; moderate certainty; absolute risk reduction = 2·3%) or in combination with lactoferrin (OR = 0·04; 95% CI: 0·01, 0·62; moderate certainty; absolute risk reduction = 6·2%) were among the interventions with moderate- or high-quality evidence that significantly reduced severe NEC. Among the intervention with moderate- or high-quality evidence relative to placebo, single-strain probiotics combined with lactoferrin (OR = 0·27; 95% CI: 0·10, 0·72; moderate certainty; absolute risk reduction = 11·00%) or alone (OR = 0·80; 95% CI: 0·65, 0·99; moderate certainty; absolute risk reduction = 2·6%) and lactoferrin alone (OR = 0·44; 95% CI: 0·27, 0·74; moderate certainty; absolute risk reduction = 5·1%) demonstrated statistically significant reduction in culture proven late-onset sepsis. Interpretation: Moderate-to-high certainty evidence demonstrates the superiority of single and multi-strain probiotics over alternative preventive treatments. Synbiotics (multiple-strain probiotics in combination with prebiotics) provide the largest reduction in morbidity and mortality in preterm infants but this is supported by only low-to-very low certainty evidence; thus, prioritizing synbiotics in future trials may provide important insights. Funding: Mitacs in partnership with Nestle Canada. Declaration of Interest: PMS is the recipient of research support provided by Lallemand Human Nutrition Inc. (Montreal, Quebec, Canada) through a Mitacs Accelerates Internship awarded to Shaiya Robinson, PhD. PMS has received honoraria for CME activities from Nestle Nutrition, Abbott Nutrition, and Mead Johnson Nutrition.

Necrotizing enterocolitis (NEC) is a devastating intestinal disease in preterm infants characterized by barrier disruption, intestinal microbial dysbiosis, and persistent inflammation of the colon, which results in high mortality rates. Current strategies used to manage this disease are not sufficient, although the use of human breast milk reduces the risk of NEC. Mother's milk is regarded as a fundamental nutritional source for neonates, but pasteurization of donor breast milk affects the composition of bioactive compounds. Current research is evaluating the benefits and potential pitfalls of adding probiotics and prebiotics to pasteurized milk so as to improve the functionality of the milk and thereby reduce the burden of illness caused by NEC. Probiotics (live micro-organisms that confer health to the host) and prebiotics (nondigestible oligosaccharides that stimulate the growth of healthy bacteria) are functional foods known to mediate immune responses and modulate microbial populations in the gut. Clinical research shows strain- and compound-specific responses when probiotics or prebiotics are administered in conjunction with donor breast milk for the prevention of NEC. Despite ongoing controversy surrounding optimal treatment strategies, randomized controlled studies are now investigating the use of synbiotics to reduce the incidence and severity of NEC. Synbiotics, a combination of probiotics and prebiotics, have been proposed to enhance beneficial health effects in the intestinal tract more than either agent administered alone. This review considers the implications of using probiotic-, prebiotic-, and synbiotic-supplemented breast milk as a strategy to prevent NEC and issues that could be encountered with the preparations.

Background Antibiotic-associated disruption of the gut microbiota is a known risk factor for Crohn's disease. This chronic inflammatory disorder results from aberrant host immune responses to subsets of the gut microbiota, and is characterized by intense neutrophil recruitment to the lamina propria, surface and crypt epithelium. Importantly, adherent-invasive Escherichia coli (AIEC) is abundant in ileal biopsies, highlighting a possible etiological role. In this study, we investigated the impact of antibiotics and AIEC challenge on murine intestinal dysbiosis and neutrophil extracellular trap activation, which is a critical component of the neutrophil antimicrobial repertoire. Methods Male C57BL/6 mice were administered vancomycin and gentamicin (once daily, 3 days), and subsequently challenged with AIEC strain LF82 (once daily, 2 days). Perturbation of the gut microbiota was monitored using a combination of molecular and phylogenetic analyses. The impact of commensal and dysbiotic gut bacterial communities on neutrophil extracellular trap mobilization and intestinal redox balance was also quantified. Results Exposure of neutrophils to murine commensal gut microbial communities activated neutrophil extracellular trap formation. The capacity of neutrophils to cast these web-like structures was exacerbated following antibiotic and AIEC-associated intestinal dysbiosis, highlighting the possible overgrowth of immune-activating intestinal pathobionts. Intestinal dysbiosis was associated with an elevated capacity of the cultivated gut bacteria to produce reactive oxygen species in vitro, and increased colonic oxidative stress in vivo. Conclusions Together, these data provide new insights into the detrimental effects of antibiotics on the gut microbiota, with clinically relevant implications for intestinal dysbiosis on neutrophil function and intestinal redox balance.

Background Health research in Canada is funded by government, health charities, foundations and industry. We investigated levels of IBD research funding and the scientific impact of this research in Canada between 2013 and 2017. Methods An analysis of global and Canadian funding in IBD research was conducted using the Canadian Institutes of Health Research (CIHR) Funded Research Database and UberResearch’s Dimensions platform. Examples of priority-driven and investigator-initiated IBD research in Canada are provided. Bibliometric analysis was used to assess the quality of IBD research output in Canada. Results Total funding for IBD research Canada between 2013 and 2017 was over $119 million Canadian dollars (CAD), with CIHR, the largest funder, contributing almost $66 million CAD, and Crohn’s and Colitis Canada, investing more than $32 million CAD. This ranks Canada fourth internationally. A comparative analysis indicates that publications by Canadian IBD researchers have a greater impact than other Canadian and international comparators. When productivity and impact in IBD research are combined, Canada is among the top three in the world. Conclusions Investment in IBD research in Canada has resulted in the development of a strong collaborative group of researchers producing impactful, world-class research. On all measures of academic productivity and influence, Canada ranks in the top two or three internationally. The challenges ahead are to continue to fund innovative IBD research and grow the next generation of IBD researchers while moving research findings into changes in health policy and practice in order to benefit affected patients and their families—and ultimately, to find the cause(s) and identify the cure(s).

Flaxseed is high in ω-3 polyunsaturated fatty acids, fiber, and lignans known to lower cholesterol levels. However, its use for prevention or treatment of inflammatory bowel diseases has yielded mixed results, perhaps related to dietary interactions. In this study, we evaluated the impact of ground flaxseed supplementation on the severity of Citrobacter rodentium-induced colitis in the setting of either a high-fat (HF, ~36%kcal) or reduced-fat (RF, ~12%kcal) diet. After weaning, C57BL/6 mice ( n = 8–15/treatment) were fed ground flaxseed (7 g/100 g diet) with either HF (HF Flx) or RF (RF Flx) diets for 4 wk before infection with C. rodentium or sham gavage. Weight changes, mucosal inflammation, pathogen burden, gut microbiota composition, tissue polyunsaturated fatty acids, and cecal short-chain fatty acids were compared over a 14-day infection period. The RF diet protected against C. rodentium-induced colitis, whereas the RF Flx diet increased pathogen burden, exacerbated gut inflammation, and promoted gut dysbiosis. When compared with the RF diet, both HF and HF Flx diets resulted in more severe pathology in response to C. rodentium infection. Our findings demonstrate that although an RF diet protected against C. rodentium-induced colitis and associated gut dysbiosis in mice, beneficial effects were diminished with ground flaxseed supplementation. NEW & NOTEWORTHY Our results demonstrate a strong protective effect of a reduced-fat diet against intestinal inflammation, dysbiosis, and pathogen burden during Citrobacter rodentium-induced colitis. However, ground flaxseed supplementation in the setting of a reduced-fat diet exacerbated colitis despite higher levels of intestinal n-3 polyunsaturated fatty acids and cecal short-chain fatty acids.

Symbiont organisms are composed of a combination of commensal and probiotic organisms thought to be decreased in disease states at the expense of increased colonization by pathobionts. The location of the epithelium between the microbiota and the underlying lamina propria, which contains nerves, blood vessels, lymphatics, stroma and immune cells, allows for bi-directional host-microbe communication to be established and regulated. The microbiota-gut-brain axis is composed of a bi-directional communication system involving the nervous system, the humoral system and the hypothalamic- pituitary-adrenal-axis. Changes to the intestinal microbiota resulting from an enteric pathogen infection are also associated with the development of changes in normal behavior. Patients with inflammatory bowel diseases and irritable bowel syndrome are prone to develop concurrent mood disorders, including anxiety and depression, which are more prevalent under conditions of perceived stress. In human studies, psychological effects of administration of a Lactobacillus/ Bifidobacteria-containing mixture to healthy volunteers were determined.

The intestinal microbiota plays a key role in shaping the host immune system. Perturbation of gut microbial composition, termed dysbiosis, is associated with an increased susceptibility to intestinal pathogens and is a hallmark of a number of inflammatory, metabolic, and infectious diseases. The prospect of mining the commensal gut microbiota for bacterial strains that can impact immune function represents an attractive strategy to counteract dysbiosis and resulting disease. In this study, we show that selective enrichment of commensal gut lactobacilli protects against the murine pathogen Citrobacter rodentium, a well-characterized model of enteropathogenic and enterohemorrhagic Escherichia coli infection. The lactobacilli-enriched bacterial culture prevented the expansion of Gammaproteobacteria and Actinobacteria and was associated with improved indexes of epithelial barrier function (dextran flux), transmissible crypt hyperplasia, and tissue inflammatory cytokine levels. Moreover, cultivation of gut bacteria from Citrobacter rodentium-infected mice reveals the differential capacity of bacterial subsets to mobilize neutrophil oxidative burst and initiate the formation of weblike neutrophil extracellular traps. Our findings highlight the beneficial effects of a lactobacilli -enriched commensal gut microenvironment and, in the context of an intestinal barrier breach, the ability of neutrophils to immobilize both commensal and pathogenic bacteria.

Background and Objective The relative contribution of genetic and environmental factors to the onset and progression of periodontitis is inconclusive. Despite the high prevalence, phenotypic heterogeneity and significant local and systemic implications of this disease, early detection and individualized therapy are problematic. Using a murine model of periodontitis in a panel of 17 recombinant inbred mice, the current study addressed the heritability of, and oral dysbiosis associated with, inflammation-mediated alveolar bone loss (iABL), the hallmark of periodontitis. Material and Methods Quantitative trait locus (QTL) genomics and quantitative PCR for over 99% of known murine oral microbiota were used. Results It was found that iABL is a polygenic trait with 32.7% heritability. One suggestive QTL, nicknamed inflammation-mediated alveolar bone loss locus (iABLL), was identified on chromosome 2. Eleven genes involved in innate immune responses and bone metabolism, particularly related to macrophage and osteoblast function, namely Etl4, Pdss1, Cobll1, 9330158F14Rik, Xirp2, Stk39, Mettl5, Metapl1, Itga6, Pdk1 and Sp3, were found in the iABLL using cis expression QTL and nonsynonymous single nucleotide polymorphism analyses. Specific oral microbiome shifts in saliva and tongue mucosa are associated with disease in this model. Conclusion Our results indicate that complex host–biofilm interactions generate pathogenic states that extend beyond subgingival biofilms and periodontal tissues. Although no temporal relationship between the onset of iABL and microbiome changes were established, our findings suggest that host factors may be responsible for pathogenic shifts in subgingival biofilms when persistent and undisturbed.

Intestinal epithelia regulate barrier integrity when challenged by inflammation, oxidative stress, and microbes. Transforming growth factor-β1 (TGF-β1) is a cytokine with known beneficial effects on intestinal epithelia, including barrier enhancement, after exposure to proinflammatory cytokines and infectious agents. The aim of this study was to determine whether TGF-β1 directly protects intestinal epithelia during hypoxia-reoxygenation (HR). Intestinal epithelial monolayers (T84, Caco-2) were exposed to either hypoxia (1% O2, 1 h) or oxidative stress (hydrogen peroxide, 1 mM), followed by normoxic atmosphere for different time points in the absence and presence of varying concentrations of TGF-β1. Transepithelial electrical resistance (TER) assessed barrier function, with RNA extracted for reverse transcription polymerase chain reaction analysis of GPx-1, HIF-1, heme-oxygenase-1 (HO-1), and NOX-1. In some experiments, intestinal epithelia were exposed to enterohemorrhagic Escherichia coli (EHEC) O157:H7 during the reoxygenation period and TER recorded 7 h after the infectious challenge. Hypoxia-reoxygenation significantly decreased TER in intestinal epithelia compared with normoxic controls. Transforming growth factor-β1 pretreatment ameliorated HR-induced epithelial barrier dysfunction in T84 (at 1 - 3 h) and Caco-2 (1 h) monolayers. Transforming growth factor-β1 preserved barrier integrity for up to 16 h after challenge with hydrogen peroxide. In TGF-β1-treated epithelial monolayers, only HO-1 mRNA significantly increased after HR (P < 0.05 vs. normoxic controls). The EHEC-induced epithelial barrier dysfunction was significantly worsened by intestinal HR (P < 0.05 vs. normoxia-EHEC-infected cells), but this was not protected by TGF-β1 pretreatment. Transforming growth factor-β1 preserves loss of epithelial barrier integrity caused by the stress of HR via a mechanism that may involve the upregulation of HO-1 transcription. Targeted treatment with TGF-β could lead to novel therapies in enteric diseases characterized by HR injury.

Lynch syndrome, the most common inherited colorectal cancer syndrome in adults, is an autosomal dominant condition caused by heterozygous germ-line mutations in DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2. Inheriting biallelic (homozygous) mutations in any of the MMR genes results in a different clinical syndrome termed biallelic mismatch repair deficiency (BMMR-D) that is characterised by gastrointestinal tumours, skin lesions, brain tumours and haematologic malignancies. This recently described and under-recognised syndrome can present with adenomatous polyps leading to early-onset small bowel and colorectal adenocarcinoma. An important clue in the family history that suggests underling BMMR-D is consanguinity. Interestingly, pedigrees of BMMR-D patients typically show a paucity of Lynch syndrome cancers and most parents are unaffected. Therefore, a family history of cancers is often non-contributory. Detection of BMMR-D can lead to more appropriate genetic counselling and the implementation of targeted surveillance protocols to achieve earlier tumour detection that will allow surgical resection. This review describes an approach for diagnosis and management of these patients and their families.

Obesity and diabetes are characterized by increased inflammation reflecting disordered control of innate immunity. We reveal a local intestinal intraepithelial lymphocyte (IEL)-GLP-1 receptor (GLP-1R) signaling network that controls mucosal immune responses. Glp1r expression was enriched in intestinal IEL preparations and copurified with markers of Tαβ and Tγδ IELs, the two main subsets of intestinal IELs. Exendin-4 increased cAMP accumulation in purified IELs and reduced the production of cytokines from activated IELs but not from splenocytes ex vivo. These actions were mimicked by forskolin, absent in IELs from Glp1r−/− mice, and attenuated by the GLP-1R agonist exendin (9-39) consistent with a GLP-1R–dependent mechanism of action. Furthermore, Glp1r−/− mice exhibited dysregulated intestinal gene expression, an abnormal representation of microbial species in feces, and enhanced sensitivity to intestinal injury following administration of dextran sodium sulfate. Bone marrow transplantation using wild-type C57BL/6 donors normalized expression of multiple genes regulating immune function and epithelial integrity in Glp1r−/− recipient mice, whereas acute exendin-4 administration robustly induced the expression of genes encoding cytokines and chemokines in normal and injured intestine. Taken together, these findings define a local enteroendocrine-IEL axis linking energy availability, host microbial responses, and mucosal integrity to the control of innate immunity.

Background and Aim Oral mucosal pathologies are frequent in inflammatory bowel disease (IBD). Since host–microbiome interactions are implicated in the pathogenesis of IBD, in this study the potential for changes affecting the oral microbiome was evaluated using two complementary mouse models of colitis: either chemically (dextran sulfate sodium) or with Citrobacter rodentium infection. Methods After sacrifice, the tongue, buccal mucosa, saliva, colon, and stool samples were collected for analyses. Denaturing gradient gel electrophoresis was performed to assess bacterial 16S rRNA gene profiles. Relative changes were determined using quantitative polymerase chain reaction analysis for the phyla Bacteroidetes, Firmicutes, Spirochetes, and Actinobacteria, classes Gammaproteobacteria and Betaproteobacteria, and the genera Bacillus and Lactobacillus. These groups represent over 99% of the oral microbiota of healthy C57BL/6 mice. Results Both models of colitis changed the oral microbiome, with the buccal microbiome being the most resistant to alterations in composition (maximum 1.8% change, vs tongue maximum 2.5% change, and saliva which demonstrated up to 7.2% total changes in microbiota composition). Changes in the oral microbiota were greater after dextran sulfate sodium challenge, compared with C. rodentium-induced colitis. Using cluster analysis, tongue and buccal mucosal microbiota composition changed ∼ 5%, saliva ∼ 35%, while stool changed ∼ 10%. Conclusion These findings indicate that dysbiosis observed in murine models of colitis is associated with changes in the composition of bacteria present in the oral cavity and in saliva. Such changes in the oral microbiota could be relevant to the etiology and management of oral mucosal pathologies observed in IBD patients.

Background Adherent-invasive Escherichia coli (AIEC) colonization has been strongly implicated in the pathogenesis of Crohn's disease. Environmental triggers such as vitamin D deficiency have emerged as key factors in the pathogenesis of inflammatory bowel diseases. The aim of this study was to investigate the effects of 1,25(OH)2D3 on AIEC infection-induced changes in vivo and in vitro. Methods Barrier function was assessed in polarized epithelial Caco-2-bbe cells grown in medium with or without vitamin D and challenged with AIEC strain LF82. Weaned C57BL/6 mice were fed either a vitamin D-sufficient or -deficient diet for 5 weeks and then infected with AIEC, in the absence and presence of low-dose dextran sodium sulphate. Disease severity was assessed by histological analysis and in vivo intestinal permeability assay. Presence of invasive bacteria was assessed by transmission electron microscopy. Results Caco-2-bbe cells incubated with 1,25(OH)2D3 were protected against AIEC-induced disruption of transepithelial electrical resistance and tight-junction protein redistribution. Vitamin D-deficient C57BL/6 mice given a course of 2% dextran sodium sulphate exhibited pronounced epithelial barrier dysfunction, were more susceptible to AIEC colonization, and showed exacerbated colonic injury. Transmission electron microscopy of colonic tissue from infected mice demonstrated invasion of AIEC and fecal microbiome analysis revealed shifts in microbial communities. Conclusions These data show that vitamin D is able to mitigate the deleterious effects of AIEC on the intestinal mucosa, by maintaining intestinal epithelial barrier homeostasis and preserving tight-junction architecture. This study highlights the association between vitamin D status, dysbiosis, and Crohn's disease.

Background Prebiotics are non-digestible food ingredients that enhance the growth of certain microbes within the gut microbiota. Prebiotic consumption generates immune-modulatory effects that are traditionally thought to reflect microbial interactions within the gut. However, recent evidence suggests they may also impart direct microbe-independent effects on the host, though the mechanisms of which are currently unclear. Methods Kinome arrays were used to profile the host intestinal signaling responses to prebiotic exposures in the absence of microbes. Identified pathways were functionally validated in Caco-2Bbe1 intestinal cell line and in vivo model of murine endotoxemia. Results We found that prebiotics directly regulate host mucosal signaling to alter response to bacterial infection. Intestinal epithelial cells (IECs) exposed to prebiotics are hyporesponsive to pathogen-induced mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) activations, and have a kinome profile distinct from non-treated cells pertaining to multiple innate immune signaling pathways. Consistent with this finding, mice orally gavaged with prebiotics showed dampened inflammatory response to lipopolysaccharide (LPS) without alterations in the gut microbiota. Conclusions These findings provide molecular mechanisms of direct host-prebiotic interactions to support prebiotics as potent modulators of host inflammation. Electronic supplementary material The online version of this article (10.1186/s40168-017-0357-4) contains supplementary material, which is available to authorized users.

Maternal separation (MS) in neonates can lead to intestinal injury. MS in neonatal mice disrupts mucosal morphology, induces colonic inflammation and increases trans-cellular permeability. Several studies indicate that intestinal epithelial stem cells are capable of initiating gut repair in a variety of injury models but have not been reported in MS. The pathophysiology of MS-induced gut injury and subsequent repair remains unclear, but communication between the brain and gut contribute to MS-induced colonic injury. Corticotropin-releasing hormone (CRH) is one of the mediators involved in the brain–gut axis response to MS-induced damage. We investigated the roles of the CRH receptors, CRHR1 and CRHR2, in MS-induced intestinal injury and subsequent repair. To distinguish their specific roles in mucosal injury, we selectively blocked CRHR1 and CRHR2 with pharmacological antagonists. Our results show that in response to MS, CRHR1 mediates gut injury by promoting intestinal inflammation, increasing gut permeability, altering intestinal morphology, and modulating the intestinal microbiota. In contrast, CRHR2 activates intestinal stem cells and is important for gut repair. Thus, selectively blocking CRHR1 and promoting CRHR2 activity could prevent the development of intestinal injuries and enhance repair in the neonatal period when there is increased risk of intestinal injury such as necrotizing enterocolitis.

The complex and diverse intestinal microbiome is recognized as important in promoting human health. An altered gut microflora, referred to as dysbiosis, is increasingly recognized as having an etiologic role in a variety of conditions, including functional gastrointestinal disorders: colic in infants and irritable bowel syndrome in older children. Probiotics are defined as live microorganisms that, if ingested in sufficient amounts, restore microbial homeostasis and have a benefit on health. Randomized controlled trials indicate that probiotics can be effective in a variety of intestinal conditions, including colic and irritable bowel syndrome. Probiotics may promote gut microbial diversity, but timing of the intervention appears crucial. Strain-specific effects on colonization resistance, epithelial barrier integrity, modulation of signal transduction, impacts on innate and adaptive immune responses, and effects on visceral hyperalgesia likely explain the observed variability in various probiotic strains. In the future, probiotics are likely to be chosen for use in a defined clinical setting based on underlying mechanism(s) of action. The precise component of the probiotic agent mediating observed effects is the subject of current research. Unresolved issues relate to optimal dosages, timing of ingestion, single versus combination formulations, maintenance of viability in storage, and the merits of employing probiotic-derived products.

Background: The Kidney Research Scientist Core Education and National Training (KRESCENT) Program was launched in 2005 to enhance kidney research capacity in Canada and foster knowledge translation across the 4 themes of health research. Objective: To evaluate the impact of KRESCENT on its major objectives and on the careers of trainees after its first 10 years. Methods: An online survey of trainees (n = 53) who had completed or were enrolled in KRESCENT was conducted in 2015. Information was also obtained from curriculum vitae (CVs). A bibliometric analysis assessed scientific productivity, collaboration, and impact in comparison with unsuccessful applicants to KRESCENT over the same period. The analysis included a comparison of Canadian with international kidney research metrics from 2000 to 2014. Results: Thirty-nine KRESCENT trainees completed the survey (74%), and 44 trainees (83%) submitted CVs. KRESCENT trainees had a high success rate at obtaining grant funding from the Canadian Institutes of Health Research (CIHR; 79%), and 76% of Post-Doctoral Fellows received academic appointments at the Assistant Professor level within 8 months of completing training. The majority of trainees reported that KRESCENT had contributed significantly to their success in securing CIHR funding (90%), and to the creation of knowledge (93%) and development of new methodologies (50%). Bibliometric analysis revealed a small but steady decline in total international kidney research output from 2000 to 2014, as a percentage of all health research, although overall impact of kidney research in Canada increased from 2000-2005 to 2009-2014 compared with other countries. KRESCENT trainees demonstrated increased productivity, multiauthored papers, impact, and international collaborations after their training, compared with nonfunded applicants. Conclusions: The KRESCENT Program has fostered kidney research career development and contributed to increased capacity, productivity, and collaboration. To further enhance knowledge creation and translation in kidney research in Canada, programs such as KRESCENT should be sustained via long-term funding partnerships.

Prebiotics are non-digestible oligosaccharides that promote the growth of beneficial gut microbes, but it is unclear whether they also have direct effects on the intestinal mucosal barrier. Here we demonstrate two commercial prebiotics, inulin and short-chain fructo-oligosaccharide (scFOS), when applied onto intestinal epithelia in the absence of microbes, directly promote barrier integrity to prevent pathogen-induced barrier disruptions. We further show that these effects involve the induction of select tight junction (TJ) proteins through a protein kinase C (PKC) δ-dependent mechanism. These results suggest that in the absence of microbiota, prebiotics can directly exert barrier protective effects by activating host cell signaling in the intestinal epithelium, which represents a novel alternative mechanism of action of prebiotics.

The complex and diverse intestinal microbiome is recognized as important in promoting human health. An altered gut microflora, referred to as dysbiosis, is increasingly recognized as having an etiologic role in a variety of conditions, including functional gastrointestinal disorders: colic in infants and irritable bowel syndrome in older children. Probiotics are defined as live microorganisms that, if ingested in sufficient amounts, restore microbial homeostasis and have a benefit on health. Randomized controlled trials indicate that probiotics can be effective in a variety of intestinal conditions, including colic and irritable bowel syndrome. Probiotics may promote gut microbial diversity, but timing of the intervention appears crucial. Strain-specific effects on colonization resistance, epithelial barrier integrity, modulation of signal transduction, impacts on innate and adaptive immune responses, and effects on visceral hyperalgesia likely explain the observed variability in various probiotic strains. In the future, probiotics are likely to be chosen for use in a defined clinical setting based on underlying mechanism(s) of action. The precise component of the probiotic agent mediating observed effects is the subject of current research. Unresolved issues relate to optimal dosages, timing of ingestion, single versus combination formulations, maintenance of viability in storage, and the merits of employing probiotic-derived products.

The gut-brain-microbiota axis is increasingly recognized as an important regulator of intestinal physiology. Exposure to psychological stress causes activation of the hypothalamic-pituitary-adrenal (HPA) axis and causes altered intestinal barrier function, intestinal dysbiosis, and behavioral changes. The primary aim of this study was to determine whether the effects of psychological stress on intestinal physiology and behavior, including anxiety and memory, are mediated by the adaptive immune system. Furthermore, we wanted to determine whether treatment with probiotics would normalize these effects. Here we demonstrate that B and T cell-deficient Rag1 −/− mice displayed altered baseline behaviors, including memory and anxiety, accompanied by an overactive HPA axis, increased intestinal secretory state, dysbiosis, and decreased hippocampal c-Fos expression. Both local (intestinal physiology and microbiota) and central (behavioral and hippocampal c-Fos) changes were normalized by pretreatment with probiotics, indicating an overall benefit on health conferred by changes in the microbiota, independent of lymphocytes. Taken together, these findings indicate a role for adaptive immune cells in maintaining normal intestinal and brain health in mice and show that probiotics can overcome this immune-mediated deficit in the gut-brain-microbiota axis.

BACKGROUND Vitamin D, an important modulator of the immune system, has been shown to protect mucosal barrier homeostasis. This study investigates the effects of vitamin D deficiency on infection-induced changes in intestinal epithelial barrier function in vitro and on Citrobacter rodentium-induced colitis in mice. METHODS Polarized epithelial Caco2-bbe cells were grown in medium with or without vitamin D and challenged with enterohemorrhagic Escherichia coli O157:H7. Barrier function and tight junction protein expression were assessed. Weaned C57BL/6 mice were fed either a vitamin D-sufficient or vitamin D-deficient diet and then infected with C. rodentium. Disease severity was assessed by histological analysis, intestinal permeability assay, measurement of inflammatory cytokine levels, and microbiome analysis. RESULTS 1,25(OH)2D3 altered E. coli O157:H7-induced reductions in transepithelial electrical resistance (P < .01), decreased permeability (P < .05), and preserved barrier integrity. Vitamin D-deficient mice challenged with C. rodentium demonstrated increased colonic hyperplasia and epithelial barrier dysfunction (P < .0001 and P < .05, respectively). Vitamin D deficiency resulted in an altered composition of the fecal microbiome both in the absence and presence of C. rodentium infection. CONCLUSIONS This study demonstrates that vitamin D is an important mediator of intestinal epithelial defenses against infectious agents. Vitamin D deficiency predisposes to more-severe intestinal injury in an infectious model of colitis.

Neutrophil extracellular traps (NETs) are an essential component of the antimicrobial repertoire and represent an effective means by which neutrophils capture, contain, and kill microorganisms. However, the uncontrolled or excessive liberation of NETs also damages surrounding cells and can contribute to disease pathophysiology. Alterations in the gut microbiota, as well as the presence of local and systemic markers of inflammation, are strongly associated with the manifestation of a spectrum of intestinal disorders, including chronic inflammatory bowel disease. Although probiotics exert beneficial effects on gut homeostasis, their direct effect on neutrophils, which are abundant in the setting of intestinal inflammation, remains unclear. In this study, we investigated the effects of nonpathogenic, enteropathogenic, and probiotic bacteria on the dynamics of NET formation. Using murine bone marrow–derived neutrophils and the neutrophil-differentiated human myeloid cell line d.HL-60, we demonstrate for the first time, to our knowledge, that probiotic Lactobacillus rhamnosus strain GG inhibits both PMA- and Staphylococcus aureus–induced formation of NETs. Moreover, probiotic L. rhamnosus strain GG had potent antioxidative activity: dampening reactive oxygen species production and phagocytic capacity of the neutrophils while protecting against cell cytotoxicity. Within the milieu of the gut, this represents a novel mechanism by which probiotics can locally dampen innate immune responses and confer desensitization toward luminal Ags.

Enterohaemorrhagic Escherichia coli O157:H7 and adherent-invasive Escherichia coli are two groups of enteric bacterial pathogens associated with haemorrhagic colitis and Crohn's Disease, respectively. Bacterial contact with host epithelial cells stimulates an immediate innate immune response designed to combat infection. In this study, immune responses of human epithelial cells to pathogens, either alone or in combination with probiotic bacteria were studied. Industrially prepared Lactobacillus helveticus strain R0052 was first examined by microarray analysis and then compared to broth-grown strains of R0052 and Lactobacillus rhamnosus strain GG using quantitative realt-time polymerase chain reaction. Results showed host immune activation responses increased following pathogen exposure, which were differentially ameliorated using probiotics depending on both the preparation of probiotics employed and conditions of exposure. These findings provide additional support for the concept that specific probiotic strains serve as a promising option for use in preventing the risk of enteric bacterial infections.

EnterohemorrhagicEscherichia coliserotype O157:H7 is a food- and waterborne pathogen that causes significant morbidity and mortality in both developing and industrialized nations. The present review focuses on the history, epidemiology and evolution of the pathogen; provides a mechanistic overview of major virulence factors (including Shiga toxins, locus of enterocyte effacement pathogenicity island and pO157 plasmid); discusses host immune responses to infection; considers available animal models; and provides an overview of current and potential future management considerations.

BACKGROUND: Funders of health research in Canada seek to determine how their funding programs impact research capacity and knowledge creation.OBJECTIVE: To evaluate the impact of a focused grants and award program that was cofunded by the Canadian Institutes of Health Research Institute of Nutrition, Metabolism and Diabetes, and the Canadian Association of Gastroenterology; and to measure the impact of the Program on the career paths of funded researchers and assess the outcomes of research supported through the Program.METHODS: A survey of the recipients of grants and awards from 2000 to 2008 was conducted in 2012. The CIHR Funding Decisions database was searched to determine subsequent funding; a bibliometric citation analysis of publications arising from the Program was performed.RESULTS: Of 160 grant and award recipients, 147 (92%) completed the survey. With >$17.4 million in research funding, support was provided for 131 fellowship awards, seven career transition awards, and 22 operating grants. More than three-quarters of grant and award recipients continue to work or train in a research-related position. Combined research outputs included 545 research articles, 130 review articles, 33 book chapters and 11 patents. Comparative analyses indicate that publications supported by the funding program had a greater impact than other Canadian and international comparators.CONCLUSIONS: Continuity in support of a long-term health research funding partnership strengthened the career development of gastroenterology researchers in Canada, and enhanced the creation and dissemination of new knowledge in the discipline.

Increasing evidence indicates that gut microorganisms impact multiple aspects of the innate and adaptive mucosal immune system. Current research focuses on the potential of prebiotics (non-digestible fibres that nourish beneficial bacteria) and probiotics (beneficial live bacteria) to promote health, prevent disease, and for use as a treatment strategy for a variety of immune-mediated conditions. The immune modulatory effects of probiotics and prebiotics are strain- or structure-specific and vary with disease state, age, and sex. Prebiotics and live beneficial bacteria, including their metabolic products or soluble mediators, have the ability to affect the composition of the intestinal microbiota. As well, they influence the integrity and functions of intestinal epithelial cells and antigen presenting cells, including dendritic cells and macrophages, by both direct and indirect mechanisms of action.Statement of novelty: This review serves to highlight select advances related to the impact of prebiotics, p...

Background: The Kidney Research Scientist Core Education and National Training (KRESCENT) Program was launched in 2005 to enhance kidney research capacity in Canada and foster knowledge translation across the 4 themes of health research. Objective: To evaluate the impact of KRESCENT on its major objectives and on the careers of trainees after its first 10 years. Methods: An online survey of trainees (n = 53) who had completed or were enrolled in KRESCENT was conducted in 2015. Information was also obtained from curriculum vitae (CVs). A bibliometric analysis assessed scientific productivity, collaboration, and impact in comparison with unsuccessful applicants to KRESCENT over the same period. The analysis included a comparison of Canadian with international kidney research metrics from 2000 to 2014. Results: Thirty-nine KRESCENT trainees completed the survey (74%), and 44 trainees (83%) submitted CVs. KRESCENT trainees had a high success rate at obtaining grant funding from the Canadian Institutes of Health Research (CIHR; 79%), and 76% of Post-Doctoral Fellows received academic appointments at the Assistant Professor level within 8 months of completing training. The majority of trainees reported that KRESCENT had contributed significantly to their success in securing CIHR funding (90%), and to the creation of knowledge (93%) and development of new methodologies (50%). Bibliometric analysis revealed a small but steady decline in total international kidney research output from 2000 to 2014, as a percentage of all health research, although overall impact of kidney research in Canada increased from 2000-2005 to 2009- 2014 compared with other countries. KRESCENT trainees demonstrated increased productivity, multiauthored papers, impact, and international collaborations after their training, compared with nonfunded applicants. Conclusions: The KRESCENT Program has fostered kidney research career development and contributed to increased capacity, productivity, and collaboration. To further enhance knowledge creation and translation in kidney research in Canada, programs such as KRESCENT should be sustained via long-term funding partnerships., Mise en contexte: Le programme KRESCENT (Kidney Research Scientist Core Education and National Training) a été lancé en 2005 pour augmenter la capacité de la recherche sur les maladies du rein à travers le Canada, et pour encourager la transmission des connaissances au sein des quatre axes de recherche en santé. Objectifs de l’étude: Cette étude avait pour but d’évaluer les répercussions du programme KRESCENT sur ses principaux objectifs ainsi que des retombées sur la carrière des stagiaires participants, dix ans après sa création. Méthodologie: Un sondage en ligne a été mené en 2015 auprès des stagiaires (n = 53) ayant été admis ou ayant complété le programme KRESCENT. Des renseignements ont également été obtenus par la consultation de curriculum vitae (CV). Une analyse bibliométrique a évalué la productivité scientifique et la collaboration des participants ainsi que les répercussions de leur participation à KRESCENT sur leur carrière. Les données de cette analyse ont été comparées à celles des candidats n’ayant pas été retenus au cours de la même période. L’analyse comprenait également une comparaison des données canadiennes avec celles obtenues en recherche sur les maladies du rein ailleurs dans le monde.

Objective: Acute gastroenteritis (AGE) is a major cause of child mortality and morbidity. This study aimed at systematically reviewing clinical practice guidelines (CPGs) on AGE to compare recommendations and provide the basis for developing single universal guidelines.Methods: CPGs were identified by searching MEDLINE, Cochrane-Library, National Guideline Clearinghouse and Web sites of relevant societies/organizations producing and/or endorsing CPGs.Results: The definition of AGE varies among the 15 CPGs identified. The parameters most frequently recommended to assess dehydration are skin turgor and sunken eyes (11/15, 73.3%), general appearance (11/15, 66.6%), capillary refill time, and mucous membranes appearance (9/15, 60%). Oral rehydration solution is universally recognized as first-line treatment. The majority of CPGs recommend hypo-osmolar (Na+ 45–60 mmol/L, 11/15, 66.6 %) or low-osmolality (Na+ 75 mmol/L, 9/15, 60%) solutions. In children who fail oral rehydration, most CPGs suggest intravenous rehydration (66.6%). However, nasogastric tube insertion for fluid administration is preferred according by 5/15 CPGs (33.3%). Changes in diet and withdrawal of food are discouraged by all CPGs, and early refeeding is strongly recommended in 13 of 15 (86.7%). Zinc is recommended as an adjunct to ORS by 10 of 15 (66.6%) CPGs, most of them from low-income countries. Probiotics are considered by 9 of 15 (60%) CPGs, 5 from high-income countries. Antiemetics are not recommended in 9 of 15 (60%) CPGs. Routine use of antibiotics is discouraged.Conclusions: Key recommendations for the management of AGE in children are similar in CPGs. Together with accurate review of evidence-base this may represent a starting point for developing universal recommendations for the management of children with AGE worldwide.

Background The composition of the intestinal microbiome seems relevant to the pathogenesis of Crohn's disease (CD), with differences in both diversity and composition of the gut microbiota in patients with CD compared with healthy individuals. However, there are still conflicting reports on the importance of various bacterial taxa in the pathogenesis of CD. The aim of this study was to characterize the composition of mucosa-associated intestinal microbiota in newly diagnosed pediatric patients with CD. Methods Mucosa-associated bacteria were identified from ileal biopsy specimens obtained at colonoscopy of 10 patients with either ileal or ileocolonic new-onset CD and 15 controls without mucosal inflammation. Microbial composition was performed by profiling the 16S rDNA V6 region using Illumina sequencing. Samples were analyzed for differences in alpha/beta diversity and also for differentially abundant taxa. Results Alpha diversity did not differ between the controls and CD cases or between CD subjects with localized ileal disease compared with those with more extensive disease. Controls also did not clearly separate from patients with CD by principal coordinate analyses; however, 117 operational taxonomic units were found to be differentially abundant between the two groups. In particular, numerous operational taxonomic units associated with Faecalibacterium prausnitzii species were increased in children with CD. Conclusions These findings contribute to emerging evidence regarding dysbiosis in pediatric CD, and provide additional evidence challenging the protective role of F. prausnitzii in CD.

Adherent-invasive Escherichia coli (AIEC) is a pathogen isolated from the ileum of patients with Crohn disease. IFNγ is a key mediator of immunity, which regulates inflammatory responses to microbial infections. Previously, we showed enterohemorrhagic E. coli prevents STAT1 activation. The aim of this study was to determine whether activation of STAT1 by IFNγ was prevented by AIEC infection, and to define the mechanisms used. Human epithelial cells were infected with three different AIEC strains or other pathogenic and commensal E. coli strains. Following infection, cells were stimulated with IFNγ, and STAT1 activation was monitored by immunoblotting. Our data show that live AIEC with active protein synthesis machinery is able to prevent IFNγ-mediated STAT1 phosphorylation, and that a secreted factor may be involved. We conclude that the suppression of epithelial cell STAT1 signal transduction by AIEC strains isolated from patients with Crohn disease represents a novel mechanism by which the pathogen evades host immune responses to the infection.

The purpose of the workshop was to receive input from the Canadian pediatric inflammatory bowel diseases research community to develop a research funding opportunity for a Canadian pediatric inflammatory bowel diseases network and data platform supported by the Canadian Institutes for Health Research, in partnership with the Foundation for Children with Intestinal and Liver Disorders. Leaders from across the country came together, with the objectives of identifying the scientific goals for a Canadian pediatric inflammatory bowel disease network, the required infrastructure, and an appropriate governance structure needed to achieve such a network and data platform, as well as other elements needed to ensure the successful implementation of a network.

Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a food-borne pathogen that causes significant morbidity and mortality in developing and industrialized nations. EHEC infection of host epithelial cells is capable of inhibiting the gamma interferon (IFN-γ) proinflammatory pathway through the inhibition of Stat-1 phosphorylation, which is important for host defense against microbial pathogens. The aim of this study was to determine the bacterial factors involved in the inhibition of Stat-1 tyrosine phosphorylation. Human HEp-2 and Caco-2 epithelial cells were challenged directly with either EHEC or bacterial culture supernatants and stimulated with IFN-γ, and then the protein extracts were analyzed by immunoblotting. The data showed that IFN-γ-mediated Stat-1 tyrosine phosphorylation was inhibited by EHEC secreted proteins. Using two-dimensional difference gel electrophoresis, EHEC Shiga toxins were identified as candidate inhibitory factors. EHEC Shiga toxin mutants were then generated and complemented in trans , and mutant culture supernatant was supplemented with purified Stx to confirm their ability to subvert IFN-γ-mediated cell activation. We conclude that while other factors are likely involved in the suppression of IFN-γ-mediated Stat-1 tyrosine phosphorylation, E. coli -derived Shiga toxins represent a novel mechanism by which EHEC evades the host immune system.

Background & AimsRAC1 is a guanosine triphosphatase that has an evolutionarily conserved role in coordinating immune defenses, from plants to mammals. Chronic inflammatory bowel diseases are associated with dysregulation of immune defenses. We studied the role of RAC1 in inflammatory bowel diseases using human genetic and functional studies and animal models of colitis.MethodsWe used a candidate gene approach to HapMap-Tag single nucleotide polymorphisms in a discovery cohort; findings were confirmed in 2 additional cohorts. RAC1 messenger RNA expression was examined from peripheral blood cells of patients. Colitis was induced in mice with conditional disruption of Rac1 in phagocytes by administration of dextran sulfate sodium.ResultsWe observed a genetic association between RAC1 with ulcerative colitis in a discovery cohort, 2 independent replication cohorts, and in combined analysis for the single nucleotide polymorphisms rs10951982 (Pcombined UC = 3.3 × 10−8, odds ratio = 1.43 [95% confidence interval: 1.26–1.63]) and rs4720672 (Pcombined UC = 4.7 × 10−6, odds ratio = 1.36 [95% confidence interval: 1.19–1.58]). Patients with inflammatory bowel disease who had the rs10951982 risk allele had increased expression of RAC1 compared to those without this allele. Conditional disruption of Rac1 in macrophage and neutrophils of mice protected against dextran sulfate sodium–induced colitis.ConclusionsHuman studies and knockout mice demonstrated a role for the guanosine triphosphatase RAC1 in the development of ulcerative colitis; increased expression of RAC1 was associated with susceptibility to colitis.

Diet has been associated with many chronic conditions that fall within the mandate of the Institute of Nutrition, Metabolism, and Diabetes (INMD) of the Canadian Institutes of Health Research. These chronic conditions represent a significant proportion of the economic and societal impact of disease in Canada. The INMD’s vision is to position Canada as a leader in knowledge creation through health research that benefits all Canadians and the global community. This document outlines the strategic priorities of the INMD and will be used to guide the use of its resources for the near future.

The Sodium Reduction Strategy for Canada includes an identification of priority areas for future research, based on a workshop convened by the Canadian Institutes of Health Research (CIHR) and partners. A strong portfolio of research is essential to addressing current developments and controversies raised in relation to the health outcomes associated with dietary sodium. CIHR aims to provide leadership in working together with other funders and partners to catalyze a broad range of sodium research.

Scope Necrotizing enterocolitis (NEC) is a leading cause of morbidity and death in preterm infants, occurring more often in formula-fed than breastfed infants. Studies in both rats and humans show that human milk oligosaccharides (HMOs) lower the incidence of NEC, but the mechanism underlying such protection is currently unclear. Methods and results By extracting HMOs from pooled human breastmilk, the impact of HMOs on the intestinal mucin levels in a murine model of NEC are investigated. To confirm the results, the findings are validated by exposing human intestinal epithelial cells and intestinal organoids to HMOs and evaluated for mucin expression. HMO-gavage to pups increases Muc2 levels and decreases intestinal permeability to macromolecular dextran. HMO-treated cells have increased Muc2 expression, decreased bacterial attachment and dextran permeability during challenge by enteric pathogens. To identify the mediators involved in HMO induction of mucins, it is demonstrated that HMOs directly induce the expression of chaperone proteins including protein disulfide isomerase (PDI). Suppression of PDI activity removes the protective effects of HMOs on barrier function in vitro as well as NEC protection in vivo. Conclusions Taken together, the results provide insights to the possible mechanisms by which HMOs protect the neonatal intestine through upregulation of mucins.