Detection of gluten immunogenic peptides in the urine of patients with coeliac disease reveals transgressions in the gluten-free diet and incomplete mucosal healing

Lateral flow assays

Lateral flow assays (LFAs) are the technology behind low-cost, simple, rapid and portable detection devices popular in biomedicine, agriculture, food and environmental sciences. This review presents an overview of the principle of the method and the critical components of the assay, focusing on lateral flow immunoassays. This type of assay has recently attracted considerable interest because of its potential to provide instantaneous diagnosis directly to patients. The range and interpretation of results and parameters used for evaluation of the assay will also be discussed. The main advantages and disadvantages of LFAs will be summarized and relevant future improvements to testing devices and strategies will be proposed. Finally, the major recent advances and future diagnostic applications in the LFA field will be explored.

Challenges in gluten-free diet in coeliac disease: Prague consensus

BACKGROUND

New treatments in coeliac disease are being vigorously pursued to either replace or facilitate the difficult-tofollow gluten-free diet.

DESIGN

The present review intends to summarise the challenges in gluten-free diet adherence during the transitional period, as reflected in the last Prague consensus, published in 2016.

RESULTS

The honourable panel members recommended that dietary adherence and the consequences of nonadherence represent key components for discussion in the transitional period setting.

CONCLUSIONS

There are numerous difficulties in adhering to gluten withdrawal, but the transition period from adolescence to young adulthood is considered a fragile and high-risk period for intentional and unintentional gluten intake.

Dietary compliance in celiac disease

Celiac disease is an immune-mediated disorder that causes severe architectural disturbance in the small intestinal mucosa of genetically-predisposed individuals. Impaired absorption of multiple nutrients results and diarrhea and weight loss develop. Evidence has accumulated that a strict gluten-free diet can result in resolution of diarrhea, weight gain and normalization of nutrient malabsorption. In addition, histopathological changes also normalize, but this histopathological response appears to be time-dependent, sex-dependent and age-dependent. Compliance to a gluten-free diet is difficult and costly resulting in poor compliance and only a limited clinical response. This poses a risk for later long-term complications, including malignancy. A major practical clinical problem is the assessment of compliance to the gluten-free diet. Although symptoms may resolve and serological antibody markers may improve, multiple studies have documented ongoing architectural disturbance and inflammatory change, and with these continued inflammatory changes, a persistent risk for long-term complications. Recent immunological studies have suggested that peptides can be detected in both urine and fecal specimens that may be indicative of limited compliance. At the same time, multiple biopsy studies have demonstrated that complete normalization of the mucosa may occur in some patients within 6 mo of initiation of a gluten-free diet, but more often, up to 2 years or more may be required before repeated biopsies eventually show mucosal recovery and mucosal healing.

Serum alkylresorcinols as biomarkers of dietary gluten exposure in coeliac disease

BACKGROUND

Therapy for coeliac disease (CD) mainly relies on following a gluten-free diet (GFD); however, a serum marker for gluten intake has yet to be established.

AIM

To evaluate the utility of alkylresorcinol concentrations for detecting gluten intake in studies of human and mouse.

METHODS

Alkylresorcinol concentrations were compared among treated patients with coeliac disease (n = 34), untreated coeliac disease patients (n = 36) and controls (n = 33). Furthermore, seven additional coeliac disease patients whose serum samples were available at diagnosis and after GFD were evaluated. In mice studies, alkylresorcinol concentrations were compared in the serum of five mice fed a regular chow and 10 mice fed lifelong with a gluten-free chow. In addition, the effect of adding gluten on changes of alkylresorcinol concentrations was also evaluated.

RESULTS

Total alkylresorcinol concentrations were significantly lower in treated with coeliac disease [median (IQR), 3 (2-8) nmol/L], compared to untreated patients [median (IQR), 32 (11-74) nmol/L; P < 0.0001] or healthy controls [median (IQR), 54 (23-112) nmol/L; P < 0.0001]. Moreover, alkylresorcinol concentrations in coeliac disease patients significantly decreased after introduction of a GFD (median, 34 nmol/L at diagnosis vs. 5 nmol/L after GFD, P = 0.02). In the mice, median (IQR) total alkylresorcinol concentrations in serum samples of mice fed lifelong with a gluten-free chow was 1.8 (1.6-2.3) nmol/L, which was further significantly increased to 16 (11-22) nmol/L after 8 days of feeding with the gluten-free chow that had gluten added to it. (P = 0.008).

CONCLUSION

Serum alkylresorcinol concentrations could be a useful marker for dietary gluten in coeliac disease.

Immunogenetic Pathogenesis of Celiac Disease and Non-celiac Gluten Sensitivity

Celiac disease is the most common oral intolerance in Western countries. It results from an immune response towards gluten proteins from certain cereals in genetically predisposed individuals (HLA-DQ2 and/or HLA-DQ8). Its pathogenesis involves the adaptive (HLA molecules, transglutaminase 2, dendritic cells, and CD4(+) T-cells) and the innate immunity with an IL-15-mediated response elicited in the intraepithelial compartment. At present, the only treatment is a permanent strict gluten-free diet (GFD). Multidisciplinary studies have provided a deeper insight of the genetic and immunological factors and their interaction with the microbiota in the pathogenesis of the disease. Similarly, a better understanding of the composition of the toxic gluten peptides has improved the ways to detect them in food and drinks and how to monitor GFD compliance via non-invasive approaches. This review, therefore, addresses the major findings obtained in the last few years including the re-discovery of non-celiac gluten sensitivity.

Biomarkers to Monitor Gluten-Free Diet Compliance in Celiac Patients

Gluten-free diet (GFD) is the only treatment for celiac disease (CD). There is a general consensus that strict GFD adherence in CD patients leads to full clinical and histological remission accompanied by improvement in quality of life and reduced long-term complications. Despite the importance of monitoring the GFD, there are no clear guidelines for assessing the outcome or for exploring its adherence. Available methods are insufficiently accurate to identify occasional gluten exposure that may cause intestinal mucosal damage. Serological tests are highly sensitive and specific for diagnosis, but do not predict recovery and are not useful for follow-up. The use of serial endoscopies, it is invasive and impractical for frequent monitoring, and dietary interview can be subjective. Therefore, the detection of gluten immunogenic peptides (GIP) in feces and urine have been proposed as new non-invasive biomarkers to detect gluten intake and verify GFD compliance in CD patients. These simple immunoassays in human samples could overcome some key unresolved scientific and clinical problems in CD management. It is a significant advance that opens up new possibilities for the clinicians to evaluate the CD treatment, GFD compliance, and improvement in the quality of life of CD patients.

Fecal Gluten Peptides Reveal Limitations of Serological Tests and Food Questionnaires for Monitoring Gluten-Free Diet in Celiac Disease Patients

OBJECTIVES

Treatment for celiac disease (CD) is a lifelong strict gluten-free diet (GFD). Patients should be followed-up with dietary interviews and serology as CD markers to ensure adherence to the diet. However, none of these methods offer an accurate measure of dietary compliance. Our aim was to evaluate the measurement of gluten immunogenic peptides (GIP) in stools as a marker of GFD adherence in CD patients and compare it with traditional methods of GFD monitoring.

METHODS

We performed a prospective, nonrandomized, multicenter study including 188 CD patients on GFD and 84 healthy controls. Subjects were given a dietary questionnaire and fecal GIP quantified by enzyme-linked immunosorbent assay (ELISA). Serological anti-tissue transglutaminase (anti-tTG) IgA and anti-deamidated gliadin peptide (anti-DGP) IgA antibodies were measured simultaneously.

RESULTS

Of the 188 celiac patients, 56 (29.8%) had detectable GIP levels in stools. There was significant association between age and GIP in stools that revealed increasing dietary transgressions with advancing age (39.2% in subjects ≥13 years old) and with gender in certain age groups (60% in men ≥13 years old). No association was found between fecal GIP and dietary questionnaire or anti-tTG antibodies. However, association was detected between GIP and anti-DGP antibodies, although 46 of the 53 GIP stool-positive patients were negative for anti-DGP.

CONCLUSIONS

Detection of gluten peptides in stools reveals limitations of traditional methods for monitoring GFD in celiac patients. The GIP ELISA enables direct and quantitative assessment of gluten exposure early after ingestion and could aid in the diagnosis and clinical management of nonresponsive CD and refractory CD. Trial registration number NCT02711397.

Symptomatic suspected gluten exposure is common among patients with coeliac disease on a gluten-free diet

BACKGROUND

A gluten-free diet is the only recommended treatment for coeliac disease.

AIM

To determine the prevalence and characteristics of reactions to gluten among persons with coeliac disease on a gluten-free diet.

METHODS

Adults with biopsy proven, newly diagnosed coeliac disease were prospectively enrolled. A survey related to diet adherence and reactions to gluten was completed at study entry and 6 months. The Coeliac Symptom Index, Coeliac Diet Assessment Tool (CDAT) and Gluten-Free Eating Assessment Tool (GF-EAT) were used to measure coeliac disease symptoms and gluten-free diet adherence.

RESULTS

Of the 105 participants, 91% reported gluten exposure <1 per month and median CDAT score was 9 (IQR 8-11), consistent with adequate adherence. A suspected symptomatic reaction to gluten was reported by 66%. Gluten consumption was unsuspected until a reaction occurred (63%) or resulted from problems ordering in a restaurant (29%). The amount of gluten consumed ranged from cross-contact (30%) to a major ingredient (10%). Median time to symptom onset was 1 h (range 10 min to 48 h), and median symptom duration was 24 h (range 1 h to 8 days). Common symptoms included abdominal pain (80%), diarrhoea (52%), fatigue (33%), headache (30%) and irritability (29%).

CONCLUSIONS

Reactions to suspected gluten exposure are common among patients with coeliac disease on a gluten-free diet. Eating at restaurants and other peoples' homes remain a risk for unintentional gluten exposure. When following individuals with coeliac disease, clinicians should include questions regarding reactions to gluten as part of their assessment of gluten-free diet adherence.

Self-Reported Prevalence of Gluten-Related Disorders and Adherence to Gluten-Free Diet in Colombian Adult Population

Background. Celiac disease seems to be rare in Colombians, but there are currently no data about the prevalence rates of symptomatic adverse reactions to gluten or adherence to gluten-free diet (GFD) in this population. Aim. to evaluate the self-reported prevalence rates of adverse reactions to gluten, adherence to GFD, and gluten-related disorders at population level in Colombia. Methods. A self-administered questionnaire-based cross-sectional study was conducted in a population from Northwest Colombia. Results. The estimated prevalence rates were (95% CI) 7.9% (6.5–9.6) and 5.3% (4.1–6.7) for adverse and recurrent adverse reactions to wheat/gluten, respectively, adherence to GFD 5.9% (4.7–7.4), wheat allergy 0.74% (0.3–1.4), and nonceliac gluten sensitivity 4.5% (3.5–5.8). There were no self-reported cases of celiac disease. Prevalence of self-reported physician-diagnosis of gluten-related disorders was 0.41% (0.17–0.96). Most respondents reported adherence to GFD without a physician-diagnosis of gluten-related disorders (97.2%). The proportion of gluten avoiders was 17.2% (15.2–19.5). Most of them did not report recurrent adverse reactions to wheat/gluten (87.0%). Conclusions. Nonceliac gluten sensitivity is rarely formally diagnosed in Colombia, but this population has the highest prevalence rate of adherence to GFD reported to date. Consequently, most respondents were avoiding wheat- and/or gluten-based products for reasons other than health-related symptoms.

Improving outcomes of refractory celiac disease - current and emerging treatment strategies

Intestinal inflammation and symptoms of celiac disease (CD) usually respond well to gluten withdrawal, but rare cases are refractory to diet. Two types of refractory CD are discriminated on the basis of the presence or absence of an atypical population of mucosal lymphocytes that may progress to enteropathy-associated T-cell lymphoma. Challenges remain in the secure diagnosis of both types of refractory disease, and evidence on which to base treatment recommendations is flawed by the small numbers of reported patients and the use of different diagnostic strategies. Recent advances in our understanding of the mechanisms of the condition in conjunction with the development of immunomodulatory agents for managing other inflammatory diseases are helping to shape future approaches to targeted therapy. Progression will depend on collaboration and recruitment to trials. In the meantime, there is evidence to suggest that earlier diagnosis and better follow-up and management of CD may prevent the development of refractoriness.

Antibody-independent identification of bovine milk-derived peptides in breast-milk

Exclusively breast-fed infants can exhibit clear signs of IgE or non IgE-mediated cow's milk allergy. However, the definite characterization of dietary cow's milk proteins (CMP) that survive the maternal digestive tract to be absorbed into the bloodstream and secreted into breast milk remains missing. Herein, we aimed at assessing possible CMP-derived peptides in breast milk. Using high performance liquid chromatography (HPLC)-high resolution mass spectrometry (MS), we compared the peptide fraction of breast milk from 12 donors, among which 6 drank a cup of milk daily and 6 were on a strict dairy-free diet. We identified two bovine β-lactoglobulin (β-Lg, 2 out 6 samples) and one αs1-casein (1 out 6 samples) fragments in breast milk from mothers receiving a cup of bovine milk daily. These CMP-derived fragments, namely β-Lg (f42-54), (f42-57) and αs1-casein (f180-197), were absent in milk from mothers on dairy-free diet. In contrast, neither intact nor hydrolyzed β-Lg was detected by western blot and competitive ELISA in any breast milk sample. Eight additional bovine milk-derived peptides identified by software-assisted MS were most likely false positive. The results of this study demonstrate that CMP-derived peptides rather than intact CMP may sensitize or elicit allergic responses in the neonate through mother's milk. Immunologically active peptides from the maternal diet could be involved in priming the newborn's immune system, driving a tolerogenic response.

Long-term care for patients with coeliac disease in the UK: a review of the literature and future directions

Coeliac disease is a common digestive disorder that affects 1% of adults. It is characterised by mucosal damage of the small intestine caused by dietary gluten. The main treatment for coeliac disease is a lifelong gluten-free diet, which can reduce morbidity and mortality and also improve quality of life. Despite the benefits, adhering to this diet is often challenging, with patients often struggling to sustain dietary restriction. Structured follow-up for coeliac disease is recommended in international guidelines for improving adherence and for detecting complications;however, uncertainty exists concerning exactly who should be administering this follow-up care. Here, we undertake a review of the current approaches described in the literature to follow-up patients with coeliac disease, and assess the efficacy of these differing models. We also explore future directions for the care of these patients in the context of the UK National Health Service (a publicly funded healthcare system). Although the focus of this review pertains to follow-up within the UK healthcare system, these problems are recognised to be international, and so the findings of our review are likely to be of interest to all healthcare professionals seeing and managing patients with coeliac disease.