Assessing DNA methylation in the developing human intestinal epithelium: potential link to inflammatory bowel disease.

DNA methylation is one of the major epigenetic mechanisms implicated in regulating cellular development and cell-type-specific gene expression. Here we performed simultaneous genome-wide DNA methylation and gene expression analysis on purified intestinal epithelial cells derived from human fetal gut, healthy pediatric biopsies, and children newly diagnosed with inflammatory bowel disease (IBD). Results were validated using pyrosequencing, real-time PCR, and immunostaining. The functional impact of DNA methylation changes on gene expression was assessed by employing in-vitro assays in intestinal cell lines. DNA methylation analyses allowed identification of 214 genes for which expression is regulated via DNA methylation, i.e. regulatory differentially methylated regions (rDMRs). Pathway and functional analysis of rDMRs suggested a critical role for DNA methylation in regulating gene expression and functional development of the human intestinal epithelium. Moreover, analysis performed on intestinal epithelium of children newly diagnosed with IBD revealed alterations in DNA methylation within genomic loci, which were found to overlap significantly with those undergoing methylation changes during intestinal development. Our study provides novel insights into the physiological role of DNA methylation in regulating functional maturation of the human intestinal epithelium. Moreover, we provide data linking developmentally acquired alterations in the DNA methylation profile to changes seen in pediatric IBD.

ESPGHAN position paper on management of percutaneous endoscopic gastrostomy in children and adolescents.

OBJECTIVES: This European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) position statement provides a comprehensive guide for health care providers to manage percutaneous endoscopic gastrostomy tubes in a safe, effective, and appropriate way. METHODS: Relevant literature from searches of PubMed, CINAHL, and recent guidelines was reviewed. In the absence of evidence, recommendations reflect the expert opinion of the authors. Final consensus was obtained by multiple e-mail exchange and during 3 face-to-face meetings of the gastroenterology committee of the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition. RESULTS: Endoscopically placed gastrostomy devices are essential in the management of children with feeding and nutritional problems. The article focuses on practical issues such as indications and contraindications. CONCLUSIONS: The decision to place an endoscopic gastrostomy has to be made by an appropriate multidisciplinary team, which then provides active follow-up and care for the child and the device.

Management guidelines of eosinophilic esophagitis in childhood.

OBJECTIVES: Eosinophilic esophagitis (EoE) represents a chronic, immune/antigen-mediated esophageal disease characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation. With few exceptions, 15 eosinophils per high-power field (peak value) in ≥1 biopsy specimens are considered a minimum threshold for a diagnosis of EoE. The disease is restricted to the esophagus, and other causes of esophageal eosinophilia should be excluded, specifically proton pump inhibitor-responsive esophageal eosinophilia. This position paper aims at providing practical guidelines for the management of children and adolescents with EoE. METHODS: Relevant literature from searches of PubMed, CINAHL, and recent guidelines was reviewed. In the absence of an evidence base, recommendations reflect the expert opinion of the authors. Final consensus was obtained during 3 face-to-face meetings of the Gastroenterology Committee and 1 teleconference. RESULTS: The cornerstone of treatment is an elimination diet (targeted or empiric elimination diet, amino acid-based formula) and/or swallowed, topical corticosteroids. Systemic corticosteroids are reserved for severe symptoms requiring rapid relief or where other treatments have failed. Esophageal dilatation is an option in children with EoE who have esophageal stenosis unresponsive to drug therapy. Maintenance treatment may be required in case of frequent relapse, although an optimal regimen still needs to be determined. CONCLUSIONS: EoE is a chronic, relapsing inflammatory disease with largely unquantified long-term consequences. Investigations and treatment are tailored to the individual and must not create more morbidity for the patient and family than the disease itself. Better maintenance treatment as well as biomarkers for assessing treatment response and predicting long-term complications is urgently needed.

A practical guide for the diagnosis of primary enteric nervous system disorders.

OBJECTIVE: Primary gastrointestinal neuropathies are a heterogeneous group of enteric nervous system (ENS) disorders that continue to cause difficulties in diagnosis and histological interpretation. Recently, an international working group published guidelines for histological techniques and reporting, along with a classification of gastrointestinal neuromuscular pathology. The aim of this article was to review and summarize the key issues for pediatric gastroenterologists on the diagnostic workup of congenital ENS disorders. In addition, we provide further commentary on the continuing controversies in the field. RESULTS: Although the diagnostic criteria for Hirschsprung disease are well established, those for other forms of dysganglionosis remain ill-defined. Appropriate tissue sampling, handling, and expert interpretation are crucial to maximize diagnostic accuracy and reduce interobserver variability. The absence of validated age-related normal values for neuronal density, along with the lack of correlation between clinical and histological findings, result in significant diagnostic uncertainties while diagnosing quantitative aberrations such as hypoganglionosis or ultrashort Hirschsprung disease. Intestinal neuronal dysplasia remains a histological description of unclear significance. CONCLUSIONS: The evaluation of cellular quantitative or qualitative abnormalities of the ENS for clinical diagnosis remains complex. Such analysis should be carried out in laboratories that have the necessary expertise and access to their own validated reference values.

Tissue transglutaminase antibody levels predict IgA deficiency.

OBJECTIVE: Measuring serum tissue transglutaminase immunoglobulin A (tTG IgA) levels is the most widely used screening test for coeliac disease. However, given an increased prevalence of IgA deficiency among coeliac patients there is a risk of false negative results. Hence, in addition to specific serum tTG IgA, screening tests frequently include total IgA levels. The objective of this study was to determine whether tTG IgA antibody levels might be used to predict IgA deficiency and hence avoid unnecessary testing of total IgA levels in all individuals. DESIGN: Retrospective analysis of 9429 serum tTG IgA and corresponding total IgA levels obtained from children and young adults in the East of England between 2007 and 2011. RESULTS: The overall prevalence of IgA deficiency was found to be very low with only 0.9% of individuals affected. Using receiver operating characteristic curve analysis we identified a cut-off value for tTG IgA of ≥0.10 µ/mL to be predictive for the absence of total IgA deficiency (IgA<0.06 g/L). Specifically, using this cut-off value, total IgA deficiency could be excluded with a sensitivity of 0.92 and specificity of 0.84. In our cohort, only 16.4% of our patient sample would have needed total IgA measurement to rule out a false negative result due to IgA deficiency. CONCLUSIONS: Our data provide a simple means of avoiding unnecessary total IgA measurements in the assessment of coeliac disease. By using tTG IgA value quantitatively, only values <0.10 µ/mL require total IgA measurements to rule out IgA deficiency and hence a potentially false negative screening result.

Colitis-associated sclerosing cholangitis in children: a single centre experience.

OBJECTIVE: Sclerosing cholangitis (SC) is an important immune-mediated extra-intestinal manifestation of inflammatory bowel disease (IBD), primarily affecting patients with ulcerative colitis (UC). The reported prevalence of SC in adults and children with UC is low at between 2 and 7%. We present findings from a hepatological work-up in children with inflammatory colitis and elevated liver function tests (LFT) from a tertiary paediatric gastroenterology unit. DESIGN: This study is designed as a retrospective review of the medical records of 17 children and adolescents with inflammatory colitis and abnormal LFTs who presented to our IBD service between April 2004 and April 2012. RESULTS: Over the eight year period a total of 52 patients were diagnosed with inflammatory colitis (ulcerative colitis and unclassified colitis). Seventeen of the 52 patients had abnormal liver function tests and underwent liver biopsy and cholangiography. All 17 patients (32.6%) were diagnosed with hepato-biliary disease. CONCLUSION: This is one of the largest reported series of children with inflammatory colitis and associated hepato-biliary disease. The data from this patient group indicate that the prevalence of IBD-associated hepato-biliary disease in children with abnormal LFTs is much higher than previously reported. As the diagnosis of IBD-associated hepato-biliary disease affects patient management, we recommend liver biopsy and cholangiography in all children with inflammatory colitis and abnormal liver function tests.

Boerhaave's syndrome: a differential diagnosis of acute chest pain following a vomiting illness / Síndrome de Boerhaave: un diagnóstico diferencial de dolor torácico, agudo tras enfermedad acompañada de vómitos

Spontaneous oesophageal rupture (Boerhaave's syndrome) is extremely rare in children. Presentation is usually in middle aged men as a result of vomiting following heavy food or alcohol consumption. We describe an unusual case of a 12-year old boy without significant past medical history presenting with acute chest pain following gastroenteritis.

La ruptura esofágica espontánea (síndrome de Boerhaave) es extremadamente rara en niños. Por lo general se presenta en hombres de mediana edad como resultado vómitos tras la ingestión de alcohol o alimentos pesados. Describimos un caso inusual de un niño de 12 años de edad sin antecedentes clínicos significativos, que acudió con dolor torácico agudo tras una gastroenteritis.

Boerhaave's syndrome: a differential diagnosis of acute chest pain following a vomiting illness.

Spontaneous oesophageal rupture (Boerhaave's syndrome) is extremely rare in children. Presentation is usually in middle aged men as a result of vomiting following heavy food or alcohol consumption. We describe an unusual case of a 12-year old boy without significant past medical history presenting with acute chest pain following gastroenteritis.

Diagnostic approach and management of cow's-milk protein allergy in infants and children: ESPGHAN GI Committee practical guidelines.

OBJECTIVES: This guideline provides recommendations for the diagnosis and management of suspected cow's-milk protein allergy (CMPA) in Europe. It presents a practical approach with a diagnostic algorithm and is based on recently published evidence-based guidelines on CMPA. DIAGNOSIS: If CMPA is suspected by history and examination, then strict allergen avoidance is initiated. In certain circumstances (eg, a clear history of immediate symptoms, a life-threatening reaction with a positive test for CMP-specific IgE), the diagnosis can be made without a milk challenge. In all other circumstances, a controlled oral food challenge (open or blind) under medical supervision is required to confirm or exclude the diagnosis of CMPA. TREATMENT: In breast-fed infants, the mother should start a strict CMP-free diet. Non-breast-fed infants with confirmed CMPA should receive an extensively hydrolyzed protein-based formula with proven efficacy in appropriate clinical trials; amino acids-based formulae are reserved for certain situations. Soy protein formula, if tolerated, is an option beyond 6 months of age. Nutritional counseling and regular monitoring of growth are mandatory in all age groups requiring CMP exclusion. REEVALUATION: Patients should be reevaluated every 6 to 12 months to assess whether they have developed tolerance to CMP. This is achieved in >75% by 3 years of age and >90% by 6 years of age. Inappropriate or overly long dietary eliminations should be avoided. Such restrictions may impair the quality of life of both child and family, induce improper growth, and incur unnecessary health care costs.

Use of small bowel MRI enteroclysis in the management of paediatric IBD.

INTRODUCTION: Children with inflammatory bowel disease (IBD) frequently present with small bowel involvement at some stage of their disease. Hence, reliable assessment of the entire small bowel is required in order to adjust treatment accordingly. Recently, magnetic resonance imaging (MRI) of the small bowel in combination with luminal contrast agent delivered via a naso-jejunal tube (MR enteroclysis) is an emerging technique demonstrating good results in adult patients. However, data on its use and benefits in children is limited. AIMS: In this study we report our experience on performing small bowel MR enteroclysis (MRE) in children with IBD. Specifically, we reviewed indications, MR findings, advantages and disadvantages of the technique in a tertiary unit. METHODS: A total of 34 MRE studies (29 paediatric IBD patients) were retrospectively analysed. All patients underwent upper and lower endoscopy under general anaesthetic (GA) the day before MR imaging was performed. Nasojejunal (NJ)-tube was placed during endoscopy. RESULTS: Frequently detected findings included small and large bowel wall thickening, small bowel strictures and intestinal lymph node enlargement. Importantly, in all our clinical cases, MRE results were key to making a clinical decision in the given scenario regardless of whether MRE findings were positive or negative. CONCLUSIONS: Within our setup, MR enteroclysis is a well-tolerated, sensitive technique for small bowel imaging, providing detailed information at crucial clinical decision points. Moreover, accurate information then allows appropriate clinical decisions to be made.

Intestinal alpha-defensin expression in pediatric inflammatory bowel disease.

BACKGROUND: Reduced alpha-defensin expression has been reported in the terminal ileum (TI) of adult patients with ileal Crohn's disease (CD). However, little is known about alpha-defensin expression in children with chronic inflammatory bowel disease (IBD). METHODS: In all, 283 intestinal biopsies were obtained from children with CD, ulcerative colitis (UC), and healthy controls. Absolute mRNA copy numbers for HD5, HD6, IL-8, Villin 1, and Tcf-4 were analyzed by reverse-transcription polymerase chain reaction (RT-PCR). HD5 immunostaining was performed on biopsy sections and patients genotyped for NOD2 mutations. RESULTS: Equal expression levels of alpha-defensins (HD5 and HD6) were found in TI biopsies of children with ileal CD (L1+L3) compared to patients with colonic disease (L2) and healthy controls. In contrast, we found significantly higher levels of alpha-defensins in the TI of children with UC compared to CD and controls. Reduced expression of Tcf-4 was observed exclusively in the duodenum and TI of CD patients with L1+L3 phenotype. We demonstrate significantly increased expression of HD5 and HD6 in the inflamed colon of IBD children (UC and CD) attributable to the presence of metaplastic Paneth cells. CONCLUSIONS: In this study no difference in alpha-defensin expression was found in the TI of CD children and controls. However, significant reduction of Tcf-4 in L1+L3 phenotype suggests that a possibly impaired PC differentiation may lead to altered HD5 and HD6 expression at some stage of disease. Additionally, substantially increased expression of alpha-defensins in the inflamed colonic mucosa of children with IBD raises the question for their potential involvement in modulating inflammation in these patients.

Aberrant response to commensal Bacteroides thetaiotaomicron in Crohn's disease: an ex vivo human organ culture study.

BACKGROUND: Human ex vivo evidence indicating that an inappropriate immune response(s) to nonpathogenic bacteria contributes to disease pathogenesis in pediatric Crohn's disease (CD) is limited. The aim of the present study was to compare and contrast the early innate immune response of pediatric "healthy" versus CD mucosa to pathogenic, probiotic, and commensal bacteria. METHODS: "Healthy control" and CD pediatric mucosal biopsies (terminal ileum and transverse colon) were cocultured for 8 hours with E. coli O42, Lactobacillus GG (LGG), Bacteroidesthetaiotaomicron (B. theta), or stimulated with interleukin (IL)-1ß (positive control). Matched nonstimulated biopsies served as experimental controls. IL-8 was the immune marker of choice. IL-8 mRNA and protein levels were quantified by quantitative polymerase chain reaction and sandwich enzyme-linked immunosorbent assay, respectively. RESULTS: IL-8 secretion was observed when control, ileal biopsies were exposed to pathogenic O42 and probiotic LGG, with no response noted to commensal B. theta. In comparison, Crohn's ileal biopsies showed impaired ability to induce IL-8 in response to O42 and LGG. Control colonic tissue showed a limited response to O42 or B. theta and LGG significantly reduced IL-8 secretion. Unlike control tissue, however, Crohn's ileal and colonic tissue did respond to B. theta, with more enhanced expression in the colon. CONCLUSIONS: We provide the first ex vivo data to support the notion that aberrant mucosal recognition of commensal bacteria may contribute to pediatric CD. While IL-8 responses to O42 and LGG varied with disease status and anatomical location, B. theta consistently induced significant IL-8 both in ileal and colonic CD tissue, which was not seen in control, healthy tissue.

A British Society of Paediatric Gastroenterology, Hepatology and Nutrition survey of the effectiveness and safety of adalimumab in children with inflammatory bowel disease.

BACKGROUND: Adalimumab is efficacious therapy for adults with Crohn's disease (CD). AIM: To summarise the United Kingdom and Republic of Ireland paediatric adalimumab experience. METHODS: British Society of Paediatric Gastroenterology, Hepatology and Nutrition (BSPGHAN) members with Inflammatory Bowel Disease (IBD) patients <18 years old commencing adalimumab with at least 4 weeks follow-up. Patient demographics and details of treatment were then collected. Response and remission was assessed using the Paediatric Crohn's Disease Activity Index (PCDAI)/Physicians Global Assessment (PGA). RESULTS: Seventy-two patients [70 CD, 1 ulcerative colitis (UC), 1 IBD unclassified (IBDU)] from 19 paediatric-centres received adalimumab at a median age of 14.8 (IQR 3.1, range 6.1-17.8) years; 66/70 CD (94%) had previously received infliximab. A dose of 80 mg then 40 mg was used for induction in 41(59%) and 40 mg fortnightly for maintenance in 61 (90%). Remission rates were 24%, 58% and 41% at 1, 6 and 12 months, respectively. Overall 43 (61%) went into remission at some point, with 24 (35%) requiring escalation of therapy. Remission rates were higher in those on concomitant immunosuppression cf. those not on immunosuppression [34/46 (74%) vs. 9/24 (37%), respectively, (χ(2) 8.8, P=0.003)]. There were 15 adverse events (21%) including four (6%) serious adverse events with two sepsis related deaths in patients who were also on immunosuppression and home parenteral nutrition (3% mortality rate). CONCLUSIONS: Adalimumab is useful in treatment of refractory paediatric patients with a remission rate of 61%. This treatment benefit should be balanced against side effects, including in this study a 3% mortality rate.

Systematic review of the evidence base for the medical treatment of paediatric inflammatory bowel disease.

OBJECTIVE: To systematically review the evidence base for the medical (pharmaceutical and nutritional) treatment of paediatric inflammatory bowel disease. METHODS: Key clinical questions were formulated regarding different treatment modalities used in the treatment of paediatric (not adult-onset) IBD, in particular the induction and maintenance of remission in Crohn disease and ulcerative colitis. Electronic searches were performed from January 1966 to December 2006, using the electronic search strategy of the Cochrane IBD group. Details of papers were entered on a dedicated database, reviewed in abstract form, and disseminated in full for appraisal. Clinical guidelines were appraised using the AGREE instrument and all other relevant papers were appraised using Scottish Intercollegiate Guidelines Network methodology, with evidence levels given to all papers. RESULTS: A total of 6285 papers were identified, of which 1255 involved children; these were entered on the database. After critical appraisal, only 103 publications met our criteria as evidence on medical treatment of paediatric IBD. We identified 3 clinical guidelines, 1 systematic review, and 16 randomised controlled trials; all were of variable quality, with none getting the highest methodological scores. CONCLUSIONS: This is the first comprehensive review of the evidence base for the treatment of paediatric IBD, highlighting the paucity of trials of high methodological quality. As a result, the development of clinical guidelines for managing children and young people with IBD must be consensus based, informed by the best-available evidence from the paediatric literature and high-quality data from the adult IBD literature, together with the clinical expertise and multidisciplinary experience of paediatric IBD experts.

Role of small-bowel endoscopy in the management of patients with inflammatory bowel disease: an international OMED-ECCO consensus.

Crohn's disease and ulcerative colitis are lifelong diseases seen predominantly in the developed countries of the world. Whereas ulcerative colitis is a chronic inflammatory condition causing diffuse and continuous mucosal inflammation of the colon, Crohn's disease is a heterogeneous entity comprised of several different phenotypes, but can affect the entire gastrointestinal tract. A change in diagnosis from Crohn's disease to ulcerative colitis during the first year of illness occurs in about 10 % - 15 % of cases. Inflammatory bowel disease (IBD) restricted to the colon that cannot be characterized as either ulcerative colitis or Crohn's disease is termed IBD-unclassified (IBDU). The advent of capsule and both single- and double-balloon-assisted enteroscopy is revolutionizing small-bowel imaging and has major implications for diagnosis, classification, therapeutic decision making and outcomes in the management of IBD. The role of these investigations in the diagnosis and management of IBD, however, is unclear. This document sets out the current Consensus reached by a group of international experts in the fields of endoscopy and IBD at a meeting held in Brussels, 12-13th December 2008, organised jointly by the European Crohn's and Colitis Organisation (ECCO) and the Organisation Mondiale d'Endoscopie Digestive (OMED). The Consensus is grouped into seven sections: definitions and diagnosis; suspected Crohn's disease; established Crohn's disease; IBDU; ulcerative colitis (including ileal pouch-anal anastomosis [IPAA]); paediatric practice; and complications and unresolved questions. Consensus guideline statements are followed by comments on the evidence and opinion. Statements are intended to be read in context with qualifying comments and not read in isolation.

Infliximab delays but does not avoid the need for surgery in treatment-resistant pediatric Crohn' disease.

The aim of this study was to review the impact of infliximab therapy on children with treatment-resistant Crohn's disease. Treatment resistance was defined as clinically active disease despite >4 months of immunosuppressive therapy. The outcome variables were time to first remission, duration of remission and the need for surgery. 24 children received 90 infusions of infliximab (16 boys; median 10.3y, range 1.0-14.4y); all had three infusions as an induction course. 17 (70.8%) achieved clinical remission, with 14/17 (82.3%) relapsing within 4 months of the third infusion. 6/7 in the non-responding group and 8/17 of the responders required surgery with an insignificant difference in the median time to surgery (p=0.49). Four remain dependent on regular infliximab. Infliximab is well-tolerated and highly effective in achieving clinical remission in children with refractory Crohn's disease but may only delay and not avoid the need for surgery. Failure to achieve clinical remission by the 3rd infusion significantly increases the risk of surgery.

Polyethylene glycol 3350 plus electrolytes for chronic constipation in children: a double blind, placebo controlled, crossover study.

OBJECTIVES: To assess the efficacy and safety of polyethylene glycol 3350 plus electrolytes (PEG+E) for the treatment of chronic constipation in children. DESIGN: Randomised, double blind, placebo controlled crossover trial, with two 2-week treatment periods separated by a 2-week placebo washout. SETTING: Six UK paediatric departments. PARTICIPANTS: 51 children (29 girls, 22 boys) aged 24 months to 11 years with chronic constipation (lasting > or =3 months), defined as < or =2 complete bowel movements per week and one of the following: pain on defaecation on 25% of days; > or =25% of bowel movements with straining; > or =25% of bowel movements with hard/lumpy stools. 47 children completed the double blind treatment. MAIN OUTCOME MEASURES: Number of complete defaecations per week (primary efficacy variable), total number of complete and incomplete defaecations per week, pain on defaecation, straining on defaecation, faecal incontinence, stool consistency, global assessment of treatment, adverse events and physical examination. RESULTS: The mean number of complete defaecations per week was significantly higher for children on PEG+E than on placebo (3.12 (SD 2.05) v 1.45 (SD 1.20), respectively; p<0.001). Further significant differences in favour of PEG+E were observed for total number of defaecations per week (p = 0.003), pain on defaecation (p = 0.041), straining on defaecation (p<0.001), stool consistency (p<0.001) and percentage of hard stools (p = 0.001). Treatment related adverse events (all mild or moderate) occurred in similar numbers of children on PEG+E (41%) and placebo during treatment (45%). CONCLUSIONS: PEG+E is significantly more effective than placebo, and appears to be safe and well tolerated in the treatment of chronic constipation in children.

Limited ileo-caecal resection for localised Crohn's disease in childhood: Clinical outcome and predictors of further surgery.

OBJECTIVES: To investigate the outcome of limited ileo-caecal resection in children with localised Crohn's disease (CD) and determine predictors of further surgery. METHODS: Review of children diagnosed with CD and operated on for ileo-caecal disease from 1995 to 2005. Age at diagnosis, endoscopic disease distribution, indication for surgery, site of recurrence and date of last follow-up were recorded. Surgery required removal of only the ileo-caecal junction and caecal pole with removal of the minimum terminal ileal length. RESULTS: Thirty seven children underwent intestinal resection. Time between primary operation and most recent follow-up was 3.8 years (range 1 month-8.8 years). Indications for surgery were obstruction/stricture (20), treatment-resistant disease (13) and abscess/perforation peritonitis (4). Follow-up was available in 32. Nine (28%) required re-laparotomy. Median time to second laparotomy was 12 months (range 4-58 months). Eighteen children required no endoscopies after surgery (median follow-up 3.4 years). CONCLUSION: Most conservative surgery occurs about 2 years after diagnosis. About 1 in 4 children have a further laparotomy within 12 months. Over half of these require division of adhesions. Limited ileo-caecal resection for localized Crohn's disease is not associated with early peri-anastomotic recurrence. Developments in laparoscopic surgery are likely to further reduce complications from adhesions.

Inflammatory bowel disease.

Twenty five per cent of inflammatory bowel disease presents in childhood. Growth and nutrition are key issues in the management with the aim of treatment being to induce and then maintain disease remission with minimal side effects. Only 25% of Crohn's disease presents with the classic triad of abdominal pain, weight loss, and diarrhoea. Most children with ulcerative colitis have blood in the stool at presentation. Inflammatory markers are usually although not invariably raised at presentation (particularly in Crohn's disease). Full investigation includes upper gastrointestinal endoscopy and ileocolonoscopy. Treatment requires multidisciplinary input as part of a clinical network led by a paediatrician with special expertise in the management of the condition.

Early interactions of Salmonella enterica serovar typhimurium with human small intestinal epithelial explants.

BACKGROUND: Salmonella enterica serovar typhimurium (S typhimurium) causes invasive gastroenteritis in humans, a disease involving significant penetration of the intestinal mucosa. However, few studies have been undertaken to investigate this interaction directly using differentiated human gut tissue. AIMS: To investigate the early interactions of an enteropathogenic strain of S typhimurium with human intestinal mucosa using human intestinal in vitro organ culture (IVOC). METHODS: Wild-type and mutant derivatives of S typhimurium TML were used to compare interactions with cultured human epithelial cells, bovine ligated loops, and human intestinal IVOC. RESULTS: S typhimurium TML was shown to attach to cultured Caco-2 brush border expressing cells and cause tissue damage and fluid accumulation in a ligated bovine loop model.S typhimurium TML bound predominantly to the mucus layer of human IVOC explants during the first four hours of IVOC incubation. From four to eight hours of IVOC incubation, small but characteristic foci of attaching and invading S typhimurium TML were detected as clusters of bacteria interacting with enterocytes, although there was no evidence for large scale invasion of explant tissues. Ruffling of enterocyte membranes associated with adherent Salmonella was visualised using electron microscopy. CONCLUSIONS: Human IVOC can be used as an alternative model for monitoring the interactions between S typhimurium and human intestinal epithelium, thus potentially offering insight into the early stages of human Salmonella induced gastroenteritis.