Intestinal permeability and antigliadin antibody test for monitoring adult patients with celiac disease

Diploid Wheats: Are They Less Immunogenic for Non-Celiac Wheat Sensitive Consumers?

Non-celiac wheat sensitivity (NCWS) is a clinical entity induced by the ingestion of gluten that leads to intestinal and/or extraintestinal symptoms, and is diagnosed when celiac disease and wheat allergy have been ruled out. In addition to gluten, other grains’ components, including amylase trypsin inhibitors (ATIs) and fermentable short-chain carbohydrates (FODMAPs), may trigger symptoms in NCWS subjects. Several studies suggest that, compared with tetraploid and hexaploid modern wheats, ancient diploid wheats species could possess a lower immunogenicity for subjects suffering from NCWS. This review aims to discuss available evidence related to the immunological features of diploid wheats compared to common wheats, and at outlining new dietary opportunities for NCWS subjects.

Diagnosis of acute graft-versus-host disease in the gastrointestinal tract of patients undergoing allogeneic hematopoietic stem cell transplantation. A descriptive and critical study of diagnostic tests

Introduction

Acute graft-versus-host disease (GVHD) is one of the major causes of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT) and has become the subject of several studies to understand and treat it.

Objective

This study does a descriptive analysis of the apoptotic index (AI) evaluation and intestinal permeability (IP) alterations in association with the clinical, endoscopic and histopathological data on patients undergoing AHSCT, with emphasis on acute intestinal graft-versus-host disease (GVHD) diagnosis.

Methods

Thirty-one patients were divided into two groups—one of patients with a clinical GVHD diagnosis and one of those without GVHD diagnosis.

Results

Thirteen deaths (41.9%) occurred during the study period, thereby reaffirming the severity of the alterations found in the patients. Fifteen patients subjected to 21 esophagogastroduodenoscopy procedures prior to D + 90 post-transplant had visible endoscopic alterations and 19 biopsies revealed histological alterations to the stomach and duodenum. Higher apoptotic indices, not reaching statistical significance, were observed in patients who died of graft versus host disease (GVHD), in the more acute forms of GVHD and where clinical GVHD was present. The intestinal permeability evaluation was performed on nine patients able to undergo it in the three proposed study periods, which showed alterations, some of which were pronounced even during pre-transplant and, therefore, the pre-conditioning phase.

Conclusion

Clinical judgment remains a fundamental tool in the diagnosis of GVHD. This study points to the known limitations of traditional diagnostic aids (endoscopy and histology) and points to new methods not usually employed in clinical practice.

Non-Celiac Gluten Sensitivity: How Its Gut Immune Activation and Potential Dietary Management Differ from Celiac Disease

Non-celiac gluten sensitivity (NCGS) is a clinical entity triggered by the ingestion of gluten-containing grains leading to intestinal and/or extraintestinal symptoms that resolve once the gluten-containing foodstuff is eliminated from the diet, and it is diagnosed when celiac disease (CD) and wheat allergy (WA) have been ruled out. The limited knowledge about the pathophysiology of NCGS and the lack of validated biomarkers are still major limitations for clinical studies, making it difficult to differentiate NCGS from other gluten-related disorders (GRD). In the absence of clear-cut diagnostic criteria, NCGS is still mainly a diagnosis of exclusion. Several studies suggest that NCGS is an immune-mediated disease that likely activates an innate immune response. Moreover, it has recently been hypothesized that in addition to gluten, other components of wheat may be responsible for the symptoms observed in individuals without CD. This review aims at discussing available evidence related to the histological and immunological features in the gut mucosa of patients with NCGS and at outlining new dietary opportunities for these patients.

Safety of Oats in Children with Celiac Disease: A Double-Blind, Randomized, Placebo-Controlled Trial

OBJECTIVE

To evaluate the long-term validity and safety of pure oats in the treatment of children with celiac disease.

STUDY DESIGN

This noninferiority clinical trial used a double-blind, placebo-controlled, crossover design extended over 15 months. Three hundred six children with a biopsy-proven diagnosis of celiac disease on a gluten-free diet for ≥2 years were randomly assigned to eat specifically prepared gluten-free food containing an age-dependent amount (15-40 g) of either placebo or purified nonreactive varieties of oats for 2 consecutive 6-month periods separated by washout standard gluten-free diet for 3 months. Clinical (body mass index, Gastrointestinal Symptoms Rating Scale score), serologic (IgA antitransglutaminase antibodies, and IgA anti-avenin antibodies), and intestinal permeability data were measured at baseline, and after 6, 9, and 15 months. Direct treatment effect was evaluated by a nonparametric approach using medians (95% CI) as summary statistic.

RESULTS

After the exclusion of 129 patients who dropped out, the cohort included 177 children (79 in the oats-placebo and 98 in the placebo-oats group; median, 0.004; 95% CI, -0.0002 to 0.0089). Direct treatment effect was not statistically significant for clinical, serologic, and intestinal permeability variables (body mass index: median, -0.5; 95% CI, -0.12 to 0.00; Gastrointestinal Symptoms Rating Scale score: median, 0; 95% CI, -2.5 to 0.00; IgA antitransglutaminase antibodies: median, -0.02; 95% CI, -0.25 to 0.23; IgA anti-avenin antibodies: median, -0.0002; 95% CI, -0.0007 to 0.0003; intestinal permeability test: median, 0.004; 95% CI, -0.0002 to 0.0089).

CONCLUSIONS

Pure nonreactive oat products are a safe dietary choice in the treatment of children with celiac disease.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00808301.

The Role of an IgA/IgG-Deamidated Gliadin Peptide Point-of-Care Test in Predicting Persistent Villous Atrophy in Patients With Celiac Disease on a Gluten-Free Diet

OBJECTIVES

Mucosal healing is important in celiac disease (CD) for the prevention of complications. However, obtaining duodenal biopsies is invasive, and there is currently no reliable surrogate marker for histological remission in clinical practice. We aimed to assess the role of a point-of-care test (POCT) based on IgA/IgG-deamidated gliadin peptide, in detecting persistent villous atrophy (VA) in CD.

METHODS

We prospectively recruited patients with CD attending endoscopy for the assessment of histological remission. All patients had IgA-endomysial (EMA) antibodies, IgA-tissue transglutaminase (TTG) antibodies, and the POCT performed, and completed a validated dietary adherence questionnaire. A gastroscopy was performed in all patients, with four biopsies taken from the second part of the duodenum and one from the duodenal bulb. We compared the diagnostic performance of the surrogate markers against duodenal histology as the reference standard.

RESULTS

A total of 217 patients with CD (70% female, age range 16-83 years, median age 53 years) on a gluten-free diet (median duration 6 years) were recruited from 2013 to 2017. Eighty-five (39.2%) patients had persistent VA. The sensitivities of the POCT, TTG, EMA, and the adherence score in detecting VA were 67.1%, 44.7%, 37.7%, and 24.7% respectively (P=0.0005). The combination of the POCT and adherence score only marginally increased the sensitivity to 70.6% (59.7-80.0%).

CONCLUSIONS

The sensitivity of the POCT was higher than the other surrogate markers in predicting VA. A POCT may provide the additional advantage of an immediate objective assessment of mucosal healing at the time of an office-based follow-up consultation.

Tests for Serum Transglutaminase and Endomysial Antibodies Do Not Detect Most Patients With Celiac Disease and Persistent Villous Atrophy on Gluten-free Diets: a Meta-analysis

BACKGROUND & AIMS

Tests to measure serum endomysial antibodies (EMA) and antibodies to tissue transglutaminase (tTG) were developed to screen for celiac disease in patients consuming gluten. However, they are commonly used to monitor patients on a gluten-free diet (GFD). We conducted a meta-analysis to assess the sensitivity and specificity of tTG IgA and EMA IgA assays in identifying patients with celiac disease who have persistent villous atrophy despite a GFD.

METHODS

We searched PUBMED, EMBASE, BIOSIS, SCOPUS, clinicaltrials.gov, Science Citation Index, and Cochrane Library databases through November 2016. Inclusion criteria were studies of subjects with biopsy-confirmed celiac disease, follow-up biopsies, and measurement of serum antibodies on a GFD, biopsy performed on subjects regardless of symptoms, or antibody test results. Our analysis excluded subjects with refractory celiac disease, undergoing gluten challenge, or consuming a prescribed oats-containing GFD. Tests were considered to have positive or negative findings based on manufacturer cut-off values. Villous atrophy was defined as a Marsh 3 lesion or villous height:crypt depth ratio below 3.0. We constructed forest plots to determine the sensitivity and specificity of detection for individual studies. For the meta-analysis, a bivariate random effects model was used to jointly model sensitivity and specificity.

RESULTS

Our search identified 5408 unique citations. Following review of abstracts, 442 articles were reviewed in detail. Only 26 studies (6 of tTG assays, 15 of EMA assays, and 5 of tTG and EMA assays) met our inclusion criteria. The most common reason studies were excluded from our analysis was inability to cross-tabulate histologic and serologic findings. The serum assays identified patients with persistent villous atrophy with high levels of specificity: 0.83 for the tTG IgA assay (95% CI, 0.79-0.87) and 0.91 for the EMA IgA assay (95% CI, 0.87-0.94). However, they detected villous atrophy with low levels of sensitivity: 0.50 for the tTG IgA assay (95% CI, 0.41-0.60) and 0.45 for the EMA IgA assay (95% CI, 0.34-0.57). The tests had similar levels of performance in pediatric and adult patients.

CONCLUSIONS

In a meta-analysis of patients with biopsy-confirmed celiac disease undergoing follow-up biopsy on a GFD, we found that tests for serum tTG IgA and EMA IgA levels had low sensitivity (below 50%) in detection of persistent villous atrophy. We need more-accurate non-invasive markers of mucosal damage in children and adults with celiac disease who are following a GFD.

Increased Intestinal Permeability in Relatives of Patients With Crohn's Disease Is Not Associated With Small Bowel Ulcerations

BACKGROUND & AIMS

Many first-degree relatives of patients with Crohn's disease (CD) have increased intestinal permeability. Video capsule endoscopy (VCE) is the most sensitive imaging test to identify small bowel mucosal lesions that could indicate subclinical CD. We aimed to estimate the association of increased intestinal permeability with small bowel ulcerations detectable by VCE in healthy first-degree relatives of patients with CD.

METHODS

We conducted a cross-sectional study of 223 healthy, asymptomatic first-degree relatives of patients with CD (parents, siblings, and children; 9-45 years old) enrolled at the University of Alberta between 2009 and 2012. Patients were given the lactulose and mannitol test to measure small bowel permeability; we used high-performance liquid chromatography to measure concentrations of lactulose and mannitol in urine samples (increased permeability defined as a ratio of lactulose/mannitol 0.025 or greater). Patients with increased permeability (n = 39) and randomly selected subjects with normal permeability (n = 59) were then examined by VCE for signs of small bowel inflammation and subclinical CD. The prevalence of small bowel lesions was compared among groups. We performed logistic regression analyses to estimate odds ratios for the association of small bowel ulcerations with intestinal permeability.

RESULTS

Among 223 first-degree relatives of patients with CD, 30% were found to have increased intestinal permeability; VCE examination found 24% of subjects to have 3 or more small bowel ulcers. Three or more small bowel ulcers were detected in 28% of patients with increased intestinal permeability and 20% of patients with normal intestinal permeability (P = .37). The adjusted odds ratio for the association of 3 or more small bowel ulcers with increased intestinal permeability was 1.5 (95% confidence interval, 0.6-3.8; P = .46).

CONCLUSIONS

Thirty percent of healthy, asymptomatic first-degree relatives of patients with CD have increased intestinal permeability. However, a strong association of small bowel ulceration seen on VCE with increased intestinal permeability was not observed.

Persistence of elevated deamidated gliadin peptide antibodies on a gluten-free diet indicates nonresponsive coeliac disease

BACKGROUND

Histologically nonresponsive coeliac disease (NRCD) is a potentially serious condition diagnosed during the follow-up of coeliac disease (CD) when patients have persistent villous atrophy despite following a gluten-free diet (GFD).

AIM

As current assessments of recovery are limited to invasive and costly serial duodenal biopsies, we sought to identify antibody biomarkers for CD patients that do not respond to traditional therapy.

METHODS

Bacterial display peptide libraries were screened by flow cytometry to identify epitopes specifically recognised by antibodies from patients with NRCD, but not by antibodies from responsive CD patients. Deamidated gliadin was confirmed to be the antigen mimicked by library peptides using ELISA with sera from NRCD (n = 15) and responsive CD (n = 45) patients on a strict GFD for at least 1 year.

RESULTS

The dominant consensus epitope sequence identified by unbiased library screening QPxx(A/P)FP(E/D) was highly similar to reported deamidated gliadin peptide (dGP) B-cell epitopes. Measurement of anti-dGP IgG titre by ELISA discriminated between NRCD and responsive CD patients with 87% sensitivity and 89% specificity. Importantly, dGP antibody titre correlated with the severity of mucosal damage indicating that IgG dGP titres may be useful to monitor small intestinal mucosal recovery on a GFD.

CONCLUSIONS

The finding of increased levels of anti-dGP IgG antibodies in CD patients on strict GFDs effectively identifies patients with NRCD. Finally, anti-dGP IgG assays may be useful to monitor mucosal damage and histological improvement in CD patients on a strict GFD.

Oats in the diet of children with celiac disease: preliminary results of a double-blind, randomized, placebo-controlled multicenter Italian study

A gluten-free diet (GFD) is currently the only available treatment for patients with celiac disease (CD). Several clinical trials have demonstrated that most celiac patients can tolerate a medium-high quantity of oats without any negative clinical effects; however, the inclusion of oats in GFD is still a matter of debate. In this study, Italian children with CD were enrolled in a 15-month, randomized, double-blind, placebo-controlled multicenter trial. Participants were randomized in two groups following either A-B treatment (6 months of diet “A”, 3 months of standard GFD, 6 months of diet “B”), or B-A treatment (6 months of diet “B”, 3 months of standard GFD, 6 months of diet “A”). A and B diets included gluten-free (GF) products (flour, pasta, biscuits, cakes and crisp toasts) with either purified oats or placebo. Clinical data (Gastrointestinal Symptoms Rate Scale [GSRS] score) and intestinal permeability tests (IPT), were measured through the study period. Although the study is still blinded, no significant differences were found in GSRS score or the urinary lactulose/mannitol (L/M) ratio between the two groups after 6 months of treatment. These preliminary results suggest that the addition of non-contaminated oats from selected varieties in the treatment of children with CD does not determine changes in intestinal permeability and gastrointestinal symptoms.

The gut barrier: new acquisitions and therapeutic approaches

The intestinal barrier serves 2 critical functions for the survival of the individual: first, it allows nutrient absorption and second, it defends the body from dangerous macromolecule penetration. It is a complex multilayer system, consisting of an external "anatomic" barrier and an inner "functional" immunological barrier. The interaction of these 2 barriers enables equilibrated permeability to be maintained. Many factors can alter this balance: gut microflora modifications, mucus layer alterations, and epithelial damage can increase intestinal permeability, allowing the translocation of luminal content to the inner layer of intestinal wall. Several techniques are now available that enable us to study gut permeability: "in vitro" models (Caco-2 and HT29-MTX cells) and "in vivo" not invasive tests (sugar tests and radioisotope scanning tests) are used to estimate permeability and to suggest molecular pathophysiological mechanisms of intestinal permeability in health and diseases. Many medicinal products used in the treatment of gastrointestinal diseases have also found to play an active role in modulate intestinal permeability: corticosteroids, 5-aminosalicylic acid, anti-tumor necrosis factor, probiotics, and mucosal protectors, like gelatin tannate. This review will particularly address the role of the gut barrier in maintaining intestinal permeability (microbiota, mucus, and epithelial cells), the techniques used for estimating intestinal permeability and the therapeutic approaches able to modify it.

Lower expression of tight junction protein 1 gene and increased FOXP3 expression in the small bowel mucosa in coeliac disease and associated type 1 diabetes mellitus

BACKGROUND

The role of regulatory T cells expressing FOXP3 in the pathogenesis of coeliac disease (CD) and type 1 diabetes (T1D) has been reported. Recent data have placed special focus on the interplay between the intestinal barrier and immunoregulatory processes. We aimed to determine whether the expression of tight junction protein 1 (TJP1), which reflects small bowel mucosa permeability, is changed in CD and T1D.

METHODS

Transcription levels of TJP1 and FOXP3 genes were evaluated in the small bowel biopsies of 14 children with CD, 12 with CD and coexisting T1D and 40 controls using real-time PCR. Serum IgA and IgG to deamidated gliadin, bovine β-lactoglobulin, bovine α-casein and human tissue transglutaminase (tTG) were determined by ELISA.

RESULTS

The highest expression of FOXP3 mRNA was seen in patients with CD and T1D compared to patients with CD alone and controls (p = 0.02). In contrast, the lowest level of TJP1 mRNA expression was found in patients with CD and T1D (p = 0.01). The levels of IgA to deamidated gliadin and tTG were highest in patients with CD and T1D (p = 0.0001 and 0.01, respectively). The expression of FOXP3 mRNA correlated highly with the level of anti-gliadin IgA (p = 0.02) and anti-tTG IgA antibodies (p = 0.004).

CONCLUSION

The significant decline in TJP1 expression in CD patients, particularly in those with coexisting T1D, was accompanied by an increase in FOXP3 expression. This might reflect an attempt to maintain immune tolerance to counterbalance the loss of mucosal integrity in the small intestine in CD associated with T1D.

Update on serologic testing in celiac disease

Contemporary serologic testing has revolutionized the field of celiac disease (CD). Highly accurate serologic assays have shown the prevalence of CD to be nearly 1:100 in many populations. These mostly ELISA (enzyme-linked immunosorbent assay)-based tests allow noninvasive screening and detection. However, the growing number of available serologic tests necessitates reevaluation of their predictive power as a single test or in combination. We review the available tests for CD, including antibodies against gliadin, endomysium, tissue transglutaminase, and deamidated gliadin, and the evidence for preferential use of specific tests in different settings. Despite several novel developments, standardized ELISA-based assays for IgA autoantibodies against tissue transglutaminase remain the test of choice for most populations. We discuss the need to develop tests for CD activity in order to assess the efficacy of upcoming nondietary therapies.

Fecal calprotectin concentration in celiac disease

GOALS

We aimed to determine fecal calprotectin (FC) concentration and its relation with histopathologic findings of children with celiac disease (CD) and to observe the probable alterations under gluten-free diet (GFD).

BACKGROUND

As FC is regarded as a marker of inflammation in the gastrointestinal tract, we hypothesized that it might be increased in untreated CD.

STUDY

The study included 29 newly diagnosed patients with CD (mean age: 6.6+/-0.6 y) and sex and age-matched 10 healthy children. All of the children with CD admitted to the hospital were classical form who has chronic diarrhea and failure to thrive. The degree of mucosal damage was graded according to the modified Marsh criteria. FC concentration was determined by enzyme-linked immunosorbent assay method on admission and after 1 year of GFD.

RESULTS

Mean FC concentration of children with CD on admission and of healthy children were 13.40+/-8.5 and 4.3+/-3.3 mg/L, respectively (P=0.004). FC concentration under GFD was 4.6+/-2.7 mg/L and there was a significant statistical difference between untreated patients and those under GFD for 1 year (P=0.001). There was no statistical difference between FC concentration of those under GFD and healthy children (P=0.8). Mean FC concentrations of children with total-villous atrophy and partial-villous atrophy were significantly different (13.8+/-9.3 mg/L vs. 3.7+/-1.8 mg/L, P=0.005).

CONCLUSIONS

It was found that FC concentration is increased in childhood CD, related to the severity of histopathologic findings and responsive to GFD. The pathogenetic mechanism by which FC is increased in CD should be investigated in further studies.

A comparison of antibody testing, permeability testing, and zonulin levels with small-bowel biopsy in celiac disease patients on a gluten-free diet

Active celiac disease is associated with positive endomysial (EMA) and tissue transglutaminase (TTG) antibodies, elevated zonulin levels, and increased intestinal permeability. There is little known about what happens to these immunologic and structural abnormalities in patients on a gluten-free diet and their correlation with small-bowel biopsy changes. Adult patients previously diagnosed with celiac disease and on a gluten-free diet for greater than 1 year were considered for the study. All patients underwent the following: measurement of EMA and TTG antibodies, serum zonulin levels, intestinal permeability (IP) testing with lactulose/mannitol ratios, food diary analysis for gluten ingestion and small- bowel biopsy. A total of 21 patients on a gluten-free diet for a mean of 9.7 years completed the study. There were ten patients who had normalization of intestinal biopsies, IP and TTG, and EM antibodies. Six patients had Marsh type 2 or 3 lesions and all had either abnormal IP (5/6) or TTG antibody (4/6). In patients with Marsh type 3 lesions, there was a correlation between IP and zonulin levels. A subgroup of patients with celiac disease on a gluten-free diet has complete normalization of intestinal biopsies, intestinal permeability defects, and antibody levels. Patients with Marsh type 3 lesions have abnormal TTG antibodies and intestinal permeability with zonulin levels that correlate with IP. These abnormalities may be due to continued gluten ingestion. Further study is needed to determine the clinical utility of TTG antibodies and IP testing in following patients with celiac disease.

Intestinal barrier gene variants may not explain the increased levels of antigliadin antibodies, suggesting other mechanisms than altered permeability

Various genes may influence intestinal barrier function, including MAGI2, MYO9B, and PARD3, which are associated with celiac disease. Because direct measurement of intestinal permeability is difficult, antibodies against gliadin (AGA) and Baker's yeast (anti-Saccharomyces cerevisiae antibodies [ASCA]) can be used as an indirect test. The objective of this study was to investigate whether intestinal permeability, represented by AGA, was correlated with MAGI2, MYO9B, and PARD3. Analyses were performed in patients with Down syndrome, a population with suspected increased intestinal permeability. Correlations between AGA and ASCA were investigated. Patients with Down syndrome (n = 126) were genotyped for six single-nucleotide polymorphisms in MAGI2 (rs1496770, rs6962966, rs9640699), MYO9B (rs1457092, rs2305764), and PARD3 (rs10763976). An allele dosage association of these risk genes and AGA levels was performed. The correlation between AGA and ASCA was studied. A strong correlation was found between AGA and ASCA (p < 0.01). The patient group with one or more risk genotypes had lower mean AGA levels (trend test p = 0.007) and consisted of a larger number of patients with normal AGA levels (p = 9.3 x 10(-5)). Celiac-associated risk genotypes are associated with lower AGA values instead of elevated ones. Thus, other immunologic phenomena play a role in the increased prevalence of elevated AGA in patients with Down syndrome, possibly involving altered induction and/or maintenance of tolerance.

The role of innate signaling in the homeostasis of tolerance and immunity in the intestine

In the intestine innate recognition of microbes is achieved through pattern recognition receptor (PRR) families expressed in immune cells and different cell lineages of the intestinal epithelium. Toll-like receptor (TLR) and nucleotide-binding and oligomerization domain-like receptor (NLR) families are emerging as key mediators of immunity through their role as maturation factors of immune cells and triggers for the production of cytokines and chemokines and antimicrobial factors. At the mucosal surface chronic activation of the immune system is avoided through the epithelial production of a glycocalyx, steady-state production of antimicrobial factors as well as the selective expression and localization of PRRs. Additionally, the polarization of epithelial TLR signaling and suppression of NF-kappaB activation by luminal commensals appears to contribute to the homeostasis of tolerance and immunity. Several studies have demonstrated that TLR signaling in epithelial cells contributes to a range of homeostatic mechanisms including proliferation, wound healing, epithelial integrity, and regulation of mucosal immune functions. The intestinal epithelium appears to have uniquely evolved to maintain mucosal tolerance and immunity, and future efforts to further understand the molecular mechanisms of intestinal homeostasis may have a major impact on human health.

The measurement and clinical significance of intestinal permeability

This article discusses the concept of intestinal permeability and the barrier function of the gut, elaborates on tight junction structure and the dynamic nature of its composition, outlines the methods for evaluating intestinal permeability, and explores abnormal intestinal permeability in clinical disease, emphasizing its possible role in the pathogenesis of autoimmune conditions. Evidence is provided from several representative diseases for a proposed model of abnormal intestinal permeability in autoimmune disease, including a description of a molecular pathway involving a signaling protein called zonulin, which appears to regulate intestinal permeability. Finally, we speculate on mechanisms that may be responsible for increasing intestinal permeability and consider clinical implications.

Systematic review: The evidence base for long-term management of coeliac disease

BACKGROUND

While gluten-free diet is an effective treatment for coeliac disease, the need for and goals of long-term management of patients are poorly defined.

AIM

To review systematically the complications and associations of coeliac disease, to identify potential risk factors, to define ways of assessing risk factors and to provide a strategy for management.

METHODS

Review of medical literature from 1975.

RESULTS

There is an increasing list of potential complications and/or conditions associated with coeliac disease, in particular, autoimmune disease, malignancy and bone disease. Risk factors that may predict or influence long-term outcomes include genetic susceptibility, environmental factors predominantly gluten ingestion, persistent small intestinal inflammation/injury and nutritional deficiencies. Genotyping of patients is yet to have an established clinical role in long-term management. Assessment of adherence to the gluten-free diet largely relies upon skilled dietary history, but the ultimate test is duodenal histopathology, which is the only currently established means of assessing healing. Symptoms, serology or other non-invasive means are poor predictors of healing and the likelihood of complications.

CONCLUSION

Evidence (albeit limited) that adherence to a gluten-free diet and mucosal healing prevent and/or ameliorate complications indicates that a planned long-term strategy for follow-up is essential.

Protease-activated receptor 2 and gut permeability: a review

Digestive tract proteases are best known for their proteolytic activity in the digestion of alimentary proteins. However, during the last decade, a possible role of proteases as signalling molecules has been emphasized with the discovery of a novel class of G-protein coupled receptors located on cell membranes that may be activated by proteolytic cleavage of their N-terminal extracellular domain. Type 2 protease-activated receptors (PAR-2) are cleaved by serine-proteases such as trypsin and tryptase. PAR-2 is present in many intestinal cell types and particularly on epithelial cells. Multiple functions have been demonstrated in the gut for PAR-2, including epithelial permeability, mainly the intercellular permeability that is of paramount importance in the equilibrium between the external milieu (digestive contents) and the submucosal immune system. Alterations of both tissue and luminal levels of proteases or serine-protease activity may affect gut permeability and subsequently the immune status of the mucosa. Activation of PAR-2 on epithelial cells may directly affect cytoskeleton contraction by triggering phosphorylation of myosin light chain with subsequent changes in tight junction permeability. Enhanced fecal protease level has been recently reported in both organic (ulcerative colitis) and functional (irritable bowel syndrome) intestinal disorders and may play a role in the pathogenesis of such diseases.