Developing strategies to improve the quality of life of patients with gluten intolerance in patients with and without coeliac disease

Gluten-Free Diet Adherence Tools for Individuals with Celiac Disease: A Systematic Review and Meta-Analysis of Tools Compared to Laboratory Tests

This systematic review aimed to find the tool that best predicts celiac individuals' adherence to a gluten-free diet (GFD). The Transparent Reporting of Multivariable Prediction Models for Individual Prognosis or Diagnosis (TRIPOD-SRMA) guideline was used for the construction and collection of data from eight scientific databases (PubMed, EMBASE, LILACS, Web of Science, LIVIVO, SCOPUS, Google Scholar, and Proquest) on 16 November 2023. The inclusion criteria were studies involving individuals with celiac disease (CD) who were over 18 years old and on a GFD for at least six months, using a questionnaire to predict adherence to a GFD, and comparing it with laboratory tests (serological tests, gluten immunogenic peptide-GIP, or biopsy). Review articles, book chapters, and studies without sufficient data were excluded. The Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modeling Studies (CHARMS) was used for data collection from the selected primary studies, and their risk of bias and quality was assessed using the Prediction Risk of Bias Assessment Tool (PROBAST). The association between the GFD adherence determined by the tool and laboratory test was assessed using the phi contingency coefficient. The studies included in this review used four different tools to evaluate GFD adherence: BIAGI score, Coeliac Dietary Adherence Test (CDAT), self-report questions, and interviews. The comparison method most often used was biopsy (n = 19; 59.3%), followed by serology (n = 14; 43.7%) and gluten immunogenic peptides (GIPs) (n = 4; 12.5%). There were no significant differences between the interview, self-report, and BIAGI tools used to evaluate GFD adherence. These tools were better associated with GFD adherence than the CDAT. Considering their cost, application time, and prediction capacity, the self-report and BIAGI were the preferred tools for evaluating GFD adherence.

Rice-Based Gluten-Free Foods and Technologies: A Review

Rice, one of the most widely consumed staples worldwide, serves as a versatile gluten-free substitute. However, review articles on technological developments in grain-free production focusing on rice are scarce. This review assesses various research results concerning the quality attributes of rice-based gluten-free foods, including bread, pasta, and beer. To optimize the key attributes in processed products, such as dough leavening in bread and the physical and cooking properties of noodles and pasta, research has focused on blending different gluten-free grains and incorporating additives that mimic the gluten function. Additionally, various processing technologies, such as starch preprocessing and extrusion puffing processes, have been employed to boost the quality of rice-based gluten-free products. Today, a variety of products, including bread, noodles, and beer, use rice as a partial replacement for barley or wheat. With rapid advancements in technology, a noticeable portion of consumers now shows a preference for products containing rice as a substitute. This trend indicates that rice-based gluten-free foods can be enhanced by leveraging the latest developments in gluten-free product technologies, particularly in countries where rice is a staple or is predominantly cultivated.

Techno-Functional and Gelling Properties of Acha (Fonio) (Digitaria exilis stapf) Flour: A Study of Its Potential as a New Gluten-Free Starch Source in Industrial Applications

Fonio (Digitaria exilis Stapf) is an ancient African cereal that represents a rich source of carbohydrate, fat, fiber, vitamins, minerals, and sulfur-containing amino acids. Processing and utilization of fonio require adequate knowledge of its structural, chemical, and nutritional characteristics. The present work evaluates the structural, techno-functional, and gelling properties of fonio and compares them to other major gluten-free cereals (rice, maize, sorghum, and millet). Fonio flour presented significantly higher water absorption index and swelling power, while it scored a lower water solubility index than the reference flours. The pasting viscosity profile of fonio was similar to that of rice, with equivalent peak viscosity but a breakdown viscosity 24% lower than rice, indicative of higher stability and resistance to shearing and heating. Rheological properties demonstrated that fonio generates gels with remarkably strong structures. At 15% concentration, fonio gel withstood stress 579% higher than those observed in the reference flours without breaking its structure. Fonio flour presented the highest gelatinization enthalpy (11.45 J/g) and a narrow gelatinization temperature range (9.96 °C), indicative of a better-packed starch structure than the other analyzed flours. The texture of the gels made with fonio showed higher firmness over the evaluated period. These combined results suggest that fonio is a suitable ingredient for gel-like food formulations.

Negative predictive value of the repeated absence of gluten immunogenic peptides in the urine of treated celiac patients in predicting mucosal healing: new proposals for follow-up in celiac disease

BACKGROUND

The treatment of celiac disease (CD) is a lifelong gluten-free diet (GFD). The current methods for monitoring GFD conformance, such as a dietary questionnaire or serology tests, may be inaccurate in detecting dietary transgressions, and duodenal biopsies are invasive, expensive, and not a routine monitoring technique.

OBJECTIVES

Our aim was to determine the clinical usefulness of urine gluten immunogenic peptides (GIP) as a biomarker monitoring GFD adherence in celiac patients and to evaluate the concordance of the results with the degree of mucosal damage.

METHODS

A prospective observational study was conducted involving 22 de novo CD patients, 77 celiac patients consuming a GFD, and 13 nonceliac subjects. On 3 d of the week, urine samples were collected and the GIP concentrations were tested. Simultaneously, anti-tissue transglutaminase antibodies, questionnaire results, clinical manifestations, and histological findings were analyzed.

RESULTS

Approximately 24% (18 of 76) of the celiac patients consuming a GFD exhibited Marsh II-III mucosal damage. Among this population, 94% (17 of 18) had detectable urine GIP; however, between 60% and 80% were asymptomatic and exhibited negative serology and appropriate GFD adherence based on the questionnaire. In contrast, 97% (31 of 32) of the celiac patients without duodenal damage had no detectable GIP. These results demonstrated the high sensitivity (94%) and negative predictive value (97%) of GIP measurements in relation to duodenal biopsy findings. In the de novo CD-diagnosed cohort, 82% (18 of 22) of patients had measurable amounts of GIP in the urine.

CONCLUSIONS

Determining GIP concentrations in several urine samples may be an especially convenient approach to assess recent gluten exposure in celiac patients and appears to accurately predict the absence of histological lesions. The introduction of GIP testing as an assessment technique for GFD adherence may help in ascertaining dietary compliance and to target the most suitable intervention during follow-up.

A compact SPR biosensor device for the rapid and efficient monitoring of gluten-free diet directly in human urine

Celiac disease (CD) is a chronic autoimmune disorder induced in genetically susceptible individuals by the ingestion of gluten from wheat, rye, barley, or certain varieties of oats. A careful diet follow-up is necessary to avoid health complications associated with long-term gluten intake by the celiac patients. Small peptides (GIP, gluten immunogenic peptides) derived from gluten digestion, which are excreted in the urine and feces, have emerged as promising biomarkers to monitor gluten intake. We have implemented a simple and sensitive label-free point-of-care (POC) device based on surface plasmon resonance for the direct detection of these biomarkers in urine. The assay employs specific monoclonal antibodies and has been optimized for the detection of the 33-mer α2-gliadin, known as the main immunogenic peptide of wheat gluten, and for the detection of GIP. Direct detection in undiluted urine has been accomplished by using biosensing chips containing a robust and stable biorecognition layer, obtained after carefully optimizing the biofunctionalization protocol. Excellent limits of detection have been reached (1.6-4.0 ng mL^-1 using mAb G12 and A1, respectively), which ensures the detection of gluten peptides even when the gluten intake is around the maximum tolerable amount in the digestive tract (< 50 mg) for celiac individuals. No sample pretreatment, extraction, or dilution is required, and the analysis takes less than 15 min. The assays have excellent reproducibility' as demonstrated by measuring spiked urine samples containing the same target concentration using different biofunctionalized chips prepared and stored at different periods of time (i.e., CV% of 3.58% and 11.30%, for G12- and A1-based assays, respectively). The assay has been validated with real samples. These features pave the way towards an end-user easy-to-handle biosensor device for the rapid monitoring of gluten-free diet (GFD) and follow-up of the health status in celiac patients.

Non-Invasive Biomarkers for Celiac Disease

Once thought to be uncommon, celiac disease has now become a common disease globally. While avoidance of the gluten-containing diet is the only effective treatment so far, many new targets are being explored for the development of new drugs for its treatment. The endpoints of therapy include not only reversal of symptoms, normalization of immunological abnormalities and healing of mucosa, but also maintenance of remission of the disease by strict adherence of the gluten-free diet (GFD). There is no single gold standard test for the diagnosis of celiac disease and the diagnosis is based on the presence of a combination of characteristics including the presence of a celiac-specific antibody (anti-tissue transglutaminase antibody, anti-endomysial antibody or anti-deamidated gliadin peptide antibody) and demonstration of villous abnormalities. While the demonstration of enteropathy is an important criterion for a definite diagnosis of celiac disease, it requires endoscopic examination which is perceived as an invasive procedure. The capability of prediction of enteropathy by the presence of the high titer of anti-tissue transglutaminase antibody led to an option of making a diagnosis even without obtaining mucosal biopsies. While present day diagnostic tests are great, they, however, have certain limitations. Therefore, there is a need for biomarkers for screening of patients, prediction of enteropathy, and monitoring of patients for adherence of the gluten-free diet. Efforts are now being made to explore various biomarkers which reflect different changes that occur in the intestinal mucosa using modern day tools including transcriptomics, proteomics, and metabolomics. In the present review, we have discussed comprehensively the pros and cons of available biomarkers and also summarized the current status of emerging biomarkers for the screening, diagnosis, and monitoring of celiac disease.

Identifying and improving adherence to the gluten-free diet in people with coeliac disease

Coeliac disease (CD) is an autoimmune gastrointestinal disorder whereby the ingestion of gluten, a storage protein found in wheat, barley and rye, causes damage to intestinal mucosa with resultant malabsorption, increased risk of anaemia and osteoporosis. Worldwide estimates suggest 1% of the population have CD. With no cure, the only treatment is a gluten-free diet (GFD). Adhering to a GFD can be very challenging; it requires knowledge, motivation and modified behaviours. Assessing adherence to a GFD is methodologically challenging. This review aims to provide an overview of the literature reporting adherence to a GFD in people with CD and the methodological challenges encountered. From six studies it has been reported that rates of adherence to a GFD range between 45 and 90% in patients of different ethnicities with CD. GF dietary adherence can be influenced by age at diagnosis, coexisting depression, symptoms on ingestion of gluten, nutrition counselling, knowledge of GF foods, understanding of food labels, cost and availability of GF foods, receiving GF foods on prescription and membership of a coeliac society. To date only five intervention studies in adults with CD have been undertaken to improve GF dietary adherence. These have included dietary and psychological counselling, and the use of online training programmes, apps, text messages and telephonic clinics. Future interventions should include people of all ethnicities, consider patient convenience and the cost-effectiveness for the healthcare environment.

How Looking for Celiac‐Safe Wheat Can Influence Its Technological Properties

Because of the continuous increase in the prevalence of gluten‐related disorders, selection of wheat with a low content of immunogenic gluten epitopes could be an innovative alternative for prevention. In this review, the focus is on literature data concerning the deallergenization tools of wheat, which are mainly related to breeding approaches (classic and advanced) and processing operations (germination and fermentation). Until now, no safe wheat genotype has been identified, whereas decreasing wheat allergenicity is possible. On the other hand, the decrease of gluten or some of its epitopes can strongly affect technological properties. Thus, obtaining celiac‐safe gluten without affecting the technological properties of wheat could be considered as a new challenge that scientists will be facing. Celiac‐safe wheat‐based product development could be a great revolution in the market of foods for special medical purposes. The present paper is aiming to: (a) review the strategies and the approaches used, or that can be used, for developing low allergenic wheat: their utilities and limits were also discussed and (b) screen the impact of gluten reduction or removal on the quality of wheat end‐use products.

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

OBJECTIVE

Gluten-free diet (GFD) is the only management for coeliac disease (CD). Available methods to assess GFD compliance are insufficiently sensitive to detect occasional dietary transgressions that may cause gut mucosal damage. We aimed to develop a method to determine gluten intake and monitor GFD compliance in patients with CD and to evaluate its correlation with mucosal damage.

DESIGN

Urine samples of 76 healthy subjects and 58 patients with CD subjected to different gluten dietary conditions were collected. A lateral flow test (LFT) with the highly sensitive and specific G12 monoclonal antibody for the most dominant gluten immunogenic peptides (GIP) and a LFT reader were used to quantify GIP in solid-phase extracted urines.

RESULTS

GIP were detectable in concentrated urines from healthy individuals previously subjected to GFD as early as 4-6 h after single gluten intake, and remained detectable for 1-2 days. The urine assay revealed infringement of the GFD in about 50% of the patients. Analysis of duodenal biopsies revealed that most of patients with CD (89%) with no villous atrophy had no detectable GIP in urine, while all patients with quantifiable GIP in urine showed incomplete intestinal mucosa recovery.

CONCLUSION

GIP are detected in urine after gluten consumption, enabling a new and non-invasive method to monitor GFD compliance and transgressions. The method was sensitive, specific and simple enough to be convenient for clinical monitoring of patients with CD as well as for basic and clinical research applications including drug development.

TRIAL REGISTRATION NUMBER

NCT02344758.

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.

Overview on the General Approaches to Improve Gluten-Free Pasta and Bread

The use of gluten-free products is increasing since a growing number of people are suffering from celiac disease and thereby need gluten-free diet. Gluten is responsible for the visco-elastic characteristics of wheat-based products; therefore, its lack makes the gluten-free products not similar to wheat-based product, with scarce textural properties. This reason constitutes the major industrial limitation. Thus, obtaining good-quality gluten-free products represents a technological challenge. This review reports the main strategies adopted to produce high quality gluten-free pasta and bread. They are mainly obtained by the utilization of specific ingredients (hydrocolloids, proteins or enzymes) to be incorporated into the standard formulation or the adoption of proper technological variables that can enhance above all the functional properties, the texture and the taste.

Elderly Onset Celiac Disease: A Narrative Review

Celiac sprue is a chronic disease, which usually occurs in children and young adults. However, it can develop in any age group, and the prevalence is increasing even in the elderly population. The atypical patterns of clinical presentation in this age group sometimes can cause a delay in diagnosis. Given the lower sensitivity and specificity of serological tests in the aged population, clinical suspect often arises in the presence of complications (autoimmune disorders, fractures, and finally, malignancy) and must be supported by endoscopic and imaging tools. In this review, we highlight the incidence and prevalence of celiac disease in the elderly, the patterns of clinical presentation, diagnosis, and the most frequent complications, with the aim of increasing awareness and reducing the diagnostic delay of celiac disease even in the elderly population.

Selective capture of most celiac immunogenic peptides from hydrolyzed gluten proteins

The available immunomethods for gluten quantitation could underestimate or overestimate the net immunoactivity of foods and beverages if the chosen analytical antibody is not specific to the relevant gluten immunogenic peptides (GIP). Accurate detection of the most active GIP is desirable to assess the potential celiac toxicity of food. We evaluated the capacity of the G12 monoclonal antibody for selectively depleting GIP in samples from two different gluteomes. Samples of hydrolyzed gliadin from wheat and a barley beer were used. The input (starting peptide digest of prolamins), the flow-through (unbound peptides), and the output (captured peptides) were analyzed by G12 and R5 competitive ELISA as well as by stimulation assays of T-cells from celiac patients. Most of the GIP were retained by the G12-agarose and represented the largest part of the immunogenicity of the gluten peptidome. G12 immunodepletion experiments with hydrolyzed gluten showed that this antibody reacted with those with the highest immunoactivity for celiac patients.

Identification and molecular characterization of oat peptides implicated on coeliac immune response

BACKGROUND

Oats provide important nutritional and pharmacological properties, although their safety in coeliac patients remains controversial. Previous studies have confirmed that the reactivity of the anti-33-mer monoclonal antibody with different oat varieties is proportional to the immune responses in terms of T-cell proliferation. Although the impact of these varieties on the adaptive response has been studied, the role of the dendritic cells (DC) is still poorly understood. The aim of this study is to characterize different oat fractions and to study their effect on DC from coeliac patients.

METHODS AND RESULTS

Protein fractions were isolated from oat grains and analyzed by SDS-PAGE. Several proteins were characterized in the prolamin fraction using immunological and proteomic tools, and by Nano-LC-MS/MS. These proteins, analogous to α- and γ-gliadin-like, showed reactive sequences to anti-33-mer antibody suggesting their immunogenic potential. That was further confirmed as some of the newly identified oat peptides had a differential stimulatory capacity on circulating DC from coeliac patients compared with healthy controls.

CONCLUSIONS

This is the first time, to our knowledge, where newly identified oat peptides have been shown to elicit a differential stimulatory capacity on circulating DC obtained from coeliac patients, potentially identifying immunogenic properties of these oat peptides.

Identification and in vitro reactivity of celiac immunoactive peptides in an apparent gluten-free beer

Gluten content from barley, rye, wheat and in certain oat varieties, must be avoid in individuals with celiac disease. In most of the Western countries, the level of gluten content in food to be considered as gluten-free products is below 20 parts per million measured by ELISA based on specific anti-gluten peptide antibody. However, in beverages or food suffering complex hydrolytic processes as beers, the relative proportion of reactive peptides for celiac patients and the analytical techniques may differ, because of the diversity of the resulting peptide populations after fermentations. A beer below 20 parts per million of gluten but yet detectable levels of gluten peptides by anti-gliadin 33-mer antibodies (G12 and A1) was analyzed. We identified and characterized the relevant peptides for either antibody recognition or immunoactivity in celiac patients. The beer was fractionated by HPLC. The relative reactivity of the different HPLC fractions to the G12/A1 antibodies correlated to the reactivity of peripheral blood mononuclear cells isolated from 14 celiac individuals. Peptides from representative fractions classified according to the relative reactivity to G12/A1 antibodies were identified by mass spectrometry. The beer peptides containing sequences with similarity to those of previously described G12 and A1 epitopes were synthesized and confirmed significant reactivity for the antibodies. The most reactive peptides for G12/A1 also confirmed the highest immunogenicity by peripheral blood mononuclear cell activation and interferon γ production from celiac patients. We concluded that preparative HPLC combined with anti-gliadin 33-mer G12/A1 antibodies were very sensitive and specific methods to analyze the relevant immunogenic peptides in hydrolyzed gluten.

The gluten-free diet: testing alternative cereals tolerated by celiac patients

A strict gluten-free diet (GFD) is the only currently available therapeutic treatment for patients with celiac disease, an autoimmune disorder of the small intestine associated with a permanent intolerance to gluten proteins. The complete elimination of gluten proteins contained in cereals from the diet is the key to celiac disease management. However, this generates numerous social and economic repercussions due to the ubiquity of gluten in foods. The research presented in this review focuses on the current status of alternative cereals and pseudocereals and their derivatives obtained by natural selection, breeding programs and transgenic or enzymatic technology, potential tolerated by celiac people. Finally, we describe several strategies for detoxification of dietary gluten. These included enzymatic cleavage of gliadin fragment by Prolyl endopeptidases (PEPs) from different organisms, degradation of toxic peptides by germinating cereal enzymes and transamidation of cereal flours. This information can be used to search for and develop cereals with the baking and nutritional qualities of toxic cereals, but which do not exacerbate this condition.

Significant differences in coeliac immunotoxicity of barley varieties

SCOPE

The only treatment available for coeliac disease (CD) is a strict diet in which the intake of wheat, barley, rye, or oats is avoided. Barley is a major cereal crop, grown mainly for its use in brewing, and it has high nutritional value. The identification of varieties with a reduced toxicity profile may contribute to improve the diet, the quality of life and health of CD patients.

METHODS AND RESULTS

Searching for harmless barleys, we investigated accessions of malting and wild barley, used for developing new cultivated cereals. The CD toxicity profile of barleys was screened using G12 antibody and cell proliferation and IFN-γ release from peripheral blood mononuclear cells and intestinal biopsies from CD patients. We found a direct correlation between the reactivity with G12 and the immunogenicity of the different barleys.

CONCLUSION

The malting barleys were less immunogenic, with reduced levels of toxic gluten, and were possibly less harmful to CD patients. Our findings could raise the prospect of breeding barley species with low levels of harmful gluten, and the attractive goal of developing nontoxic barley cultivars, always taking into account the Codex standard for foods for special dietary use for persons intolerant to gluten.