Raymond J. Playford

Newly identified genetic risk variants for celiac disease related to the immune response

Our genome-wide association study of celiac disease previously identified risk variants in the IL2–IL21 region. To identify additional risk variants, we genotyped 1,020 of the most strongly associated non-HLA markers in an additional 1,643 cases and 3,406 controls. Through joint analysis including the genome-wide association study data (767 cases, 1,422 controls), we identified seven previously unknown risk regions (P < 5 × 10−7). Six regions harbor genes controlling immune responses, including CCR3, IL12A, IL18RAP, RGS1, SH2B3 (nsSNP rs3184504) and TAGAP. Whole-blood IL18RAP mRNA expression correlated with IL18RAP genotype. Type 1 diabetes and celiac disease share HLA-DQ, IL2–IL21, CCR3 and SH2B3 risk regions. Thus, this extensive genome-wide association follow-up study has identified additional celiac disease risk variants in relevant biological pathways.

CAMPYLOBACTER PYLORI AND DUODENAL ULCERS: THE GASTRIN LINK

The possibility that Campylobacter pylori (CP) in the gastric antrum stimulates gastrin release in duodenal ulcer (DU) disease was examined in 31 patients. The 25 patients with antral colonisation with CP had higher basal and meal-stimulated plasma gastrin concentrations, and higher peak acid output (PAO), than did the 6 without CP in the autumn.

Muramyl dipeptide and toll-like receptor sensitivity in NOD2-associated Crohn's disease

Both NOD2 (CARD15) alleles are mutated in roughly 15% of patients with Crohns disease, but functional effects are unclear. We analysed the cytokine response of peripheral blood mononuclear cells to muramyl dipeptide (MDP), the ligand for NOD2. MDP induced little TNFalpha or interleukin 1beta, but strong interleukin-8 secretion. MDP also substantially upregulated secretion of TNFalpha and interleukin 1beta induced by toll-like receptor ligands. These effects were abolished by the most common Crohns NOD2 double mutant genotypes at low nanomolar MDP concentrations, and provide the basis to develop a test of NOD2 functional deficiency. In Crohns disease, there are defects in neutrophil recruitment driven by NOD2 and interleukin 8 and in cross talk between the NOD2 and toll-like receptor pathways, which suggests that the immune system fails to receive an early priming signal.

Human spasmolytic polypeptide is a cytoprotective agent that stimulates cell migration

BACKGROUND/AIMS Gastric epithelium is attacked by acid, pepsin, and ingested agents. When a mucosal lesion occurs, the defect is rapidly closed by cell migration. Because spasmolytic polypeptide is rapidly produced at sites of injury, we postulated that human spasmolytic polypeptide (hSP) was important in mucosal repair. Recombinant hSP was used to test this hypothesis. METHODS The ulcer healing effect of various doses of hSP administered orally and subcutaneously was examined using an indomethacin (20 mg/kg) restraint rat model of gastric damage. Stability of hSP in gastrointestinal juice was determined using size-exclusion chromatography. The effect of hSP on migration of human colonic carcinoma cell lines HT29 and SW480 was determined using collagen gel invasion and wounded monolayer assays. Proliferation was assessed using [3H]thymidine incorporation and toluidine blue staining. RESULTS Infusions of hSP at 25 and 50 micrograms.kg-1.h-1 subcutaneously decreased gastric damage by about 50% (P < 0.01) without changing acid secretion. Oral hSP was ineffective. hSP was stable in gastrointestinal juice. hSP stimulated migration of HT29 cells but did not affect proliferation and had no effect on SW480 cells. CONCLUSIONS hSP may play a key role in the early stages of mucosal repair by stimulating the initial re-epithelialization by cell migration.

Characterization and Clinical Application of Human CD34+ Stem/Progenitor Cell Populations Mobilized into the Blood by Granulocyte Colony‐Stimulating Factor

A phase I study was performed to determine the safety and tolerability of injecting autologous CD34+ cells into five patients with liver insufficiency. The study was based on the hypothesis that the CD34+ cell population in granulocyte colony‐stimulating factor (G‐CSF)‐mobilized blood contains a subpopulation of cells with the potential for regenerating damaged tissue. We separated a candidate CD34+ stem cell population from the majority of the CD34+ cells (99%) by adherence to tissue culture plastic. The adherent and nonadherent CD34+ cells were distinct in morphology, immunophenotype, and gene expression profile. Reverse transcription‐polymerase chain reaction‐based gene expression analysis indicated that the adherent CD34+ cells had the potential to express determinants consistent with liver, pancreas, heart, muscle, and nerve cell differentiation as well as hematopoiesis. Overall, the characteristics of the adherent CD34+ cells identify them as a separate putative stem/progenitor cell population. In culture, they produced a population of cells exhibiting diverse morphologies and expressing genes corresponding to multiple tissue types. Encouraged by this evidence that the CD34+ cell population contains cells with the potential to form hepatocyte‐like cells, we gave G‐CSF to five patients with liver insufficiency to mobilize their stem cells for collection by leukapheresis. Between 1 × 106 and 2 × 108 CD34+ cells were injected into the portal vein (three patients) or hepatic artery (two patients). No complications or specific side effects related to the procedure were observed. Three of the five patients showed improvement in serum bilirubin and four of five in serum albumin. These observations warrant further clinical trials.

New British Society of Gastroenterology (BSG) guidelines for the diagnosis and management of Barrett’s oesophagus

The main changes in the recommended guidelines for the management of Barretts oesophagus by the British Society of Gastroenterology are highlighted, together with their value in the context of the numerous other guidelines and manuscripts that are already available

Guidelines for the investigation of chronic diarrhoea, 2nd edition

1.0 PREFACE 1.1 Purpose of guidelines These guidelines were compiled at the request of the Chairman of the British Society of Gastroenterology’s clinical services committee. The guidelines are directed at consultant gastroenterologists, specialist registrars in training, and general practitioners, and refer specifically to adult not paediatric gastroenterology. Their purpose is to provide guidance on the best available methods of investigating symptoms of chronic diarrhoea. Given this broad symptom based focus, the guidelines cover a wide range of gastroenterological conditions and are not intended as a comprehensive review of all aspects of the clinical conditions mentioned herein, but rather an attempt to rationalise the approach to investigation in the context of this common clinical scenario. 1.2 Development of guidelines The guidelines were prepared following a comprehensive literature search by Dr PD Thomas. This involved a review of electronic databases (Medline and PubMed) using keywords such as “diarrhea”, “chronic”, “diagnostic evaluation”, “investigation”, “malabsorption”, and terms related to the specific conditions mentioned in the text (for example, coeliac disease and small bowel bacterial overgrowth). Papers relating to diarrhoea in the context of immunodeficiency syndromes were specifically excluded from this review as this subject was felt to require a different investigative approach. A total of 530 key papers and relevant abstracts in English in peer reviewed journals were identified and read, and relevant work has been cited and referenced. An initial draft document was produced and subsequently reviewed and modified by a multidisciplinary group comprising clinical gastroenterologists, radiologists, and biochemists.

Final results from 10 year cohort of patients undergoing surveillance for Barrett's oesophagus: observational study

Abstract Objectives: To review the benefit of an endoscopic surveillance programme for patients with Barretts oesophagus. Design: Observational study. Setting: University teaching hospital. Participants: 409 patients in whom Barretts oesophagus was identified during 1984-94; 143 were entered into the annual surveillance programme. Main outcome measures: Development of dysplasia and cancer and mortality. Results: The average period of surveillance was 4.4 years; 55 patients were reassessed in 1994 but only eight remained in the programme in 1999, withdrawal being due to death (not from carcinoma of the oesophagus), illness, or frailty. Five of the patients who entered surveillance developed carcinoma of the oesophagus. Only one cancer was identified as a result of a surveillance endoscopy, the others being detected during endoscopy to investigate altered symptoms. Of the 266 patients who were not suitable for surveillance, one died from oesophageal cancer and 103 from other causes. Surveillance has resulted in 745 endoscopies and about 3000 biopsy specimens. Conclusion: The current surveillance strategy has limited value, and it may be appropriate to restrict surveillance to patients with additional risk factors such as stricture, ulcer, or long segment (>80 mm) Barretts oesophagus.

The epidermal growth factor receptor (EGF-R) is present on the basolateral, but not the apical, surface of enterocytes in the human gastrointestinal tract.

BACKGROUND: While it is clear that luminal epidermal growth factor (EGF) stimulates repair of the damaged bowel, its significance in maintaining normal gut growth remains uncertain. If EGF is important in maintaining normal gut growth, the EGF receptor (EGF-R) should be present on the apical (luminal) surface in addition to the basolateral surface. AIMS/SUBJECTS/METHODS: This study examined the distribution of the EGF-R in the epithelium throughout the human gastro-intestinal tract using immunohistochemistry, electron microscopy, and western blotting of brush border preparations. RESULTS: Immunostaining of the oesophagus showed circumferential EGF-R positivity in the cells of the basal portions of the stratified squamous epithelium but surface cells were EGF-R negative. In the normal stomach, small intestine, and colon, immunostaining localised the receptor to the basolateral surface with the apical membranes being consistently negative. EGF-R positivity within the small intestine appeared to be almost entirely restricted to the proliferative (crypt) region. Western blotting demonstrated a 170 kDa protein in whole tissue homogenates but not in the brush border vesicle preparations. CONCLUSIONS: As the EGF-R is located only on the basolateral surfaces in the normal adult gastrointestinal tract, the major role of luminal EGF is probably to stimulate repair rather than to maintain normal gut growth.

Synergistic enhancement of Toll-like receptor responses by NOD1 activation

NOD1 is an intracellular pattern‐recognition receptor specific for Gram‐negative peptidoglycan that is important in host response to infections (e.g. Helicobacter pylori and Shigella flexneri). Genetic variation in NOD1 predisposes to asthma and inflammatory bowel disease. Functional responses have not previously been studied in primary human cells. NOD1 activation by low nanomolar concentrations of the specific muropeptide ligand M‐TriDAP induced minimal human peripheral blood mononuclear cell TNF‐α, IL‐1β or IL‐10 secretion, but synergistically increased Toll‐like receptor (TLR)‐induced responses. Synergistic responses were seen across multiple ligands (to TLR1/2, 2/6, 4, 5, 7/8) and a broad range of cytokine secretion (TNF‐α, IL‐1α, IL‐1β, IL‐4, IL‐6, IL‐10, GM‐CSF). Synergy was also observed in the allogeneic mixed lymphocyte reaction. These responses were similar in cells homozygous for Crohns disease‐associated NOD2 mutations. In contrast to cell lines, primary human peripheral blood mononuclear cells respond to NOD1 muropeptides at ∼ 100‐fold lower concentrations. Cross‐talk between cytosolic NOD1 and membrane‐bound TLR enhances responses to the multiple antigens simultaneously presented by a microbe.