Double-Blind Randomized Clinical Trial: Gluten versus Placebo Rechallenge in Patients with Lymphocytic Enteritis and Suspected Celiac Disease

Molecular Triggers of Non-celiac Wheat Sensitivity: A Scoping Review and Analysis

INTRODUCTION

Nonceliac wheat sensitivity (NCWS) is characterized by a symptomatic response to the ingestion of foods containing wheat and related cereal grains in the absence of celiac disease or wheat allergy. Despite efforts to identify the constituent component(s) of wheat responsible for triggering NCWS, no consensus has emerged, leading to competing claims. We aimed to systematically evaluate the literature and provide an evidence-based conclusion on the contribution of specific wheat components to NCWS.

METHODS

A comprehensive search of multiple bibliographic databases was conducted, focusing on primary research. Data were systematically analyzed, and methodological gaps were identified.

RESULTS

The search identified 175 unique citations, revealing 3 categories of compounds frequently considered as potential triggers of NCWS: gluten, fermentable carbohydrates, and amylase/trypsin inhibitors (ATIs). Among 16 double-blind placebo-controlled studies, 8 reported a greater symptomatic response to gluten than the control. Only 1 controlled study examined fermentable carbohydrates, finding a modest effect, but the tested carbohydrates were not derived from wheat. No eligible studies assessed ATIs or other wheat-related compounds as potential NCWS triggers. Across studies, significant limitations and methodological inconsistencies were noted, particularly in participant selection, challenge protocols, and data reporting.

DISCUSSION

Gluten is the most extensively investigated wheat component linked to NCWS, but evidence for its role is inconsistent and undermined by methodological limitations. No direct evidence currently links wheat fermentable carbohydrates, ATIs, or other components to NCWS symptoms. The existing evidence is insufficient to justify restricting specific components of wheat in the management of NCWS. Future studies must overcome the identified gaps to rigorously investigate the role of wheat and related cereals in NCWS, with the potential to advance diagnosis and treatment.

Improving the Diagnosis of Dermatitis Herpetiformis Using the Intraepithelial Lymphogram

Dermatitis herpetiformis is a cutaneous manifestation of celiac disease. Phenotyping of intraepithelial lymphocytes in the small bowel mucosa can strengthen the diagnosis of celiac disease when it is not clear-cut. We aim to evaluate the usefulness of the intraepithelial lymphogram to confirm dermatitis herpetiformis in equivocal cases. We performed a retrospective multicenter study on patients diagnosed with dermatitis herpetiformis and collected data from the intraepithelial lymphogram assessed by flow cytometry. A total of 36 patients were analyzed in relation to the severity of intestinal damage (18 had non-atrophic mucosa) at baseline (N = 28) and/or after the adoption of a gluten-free diet (median follow-up of three years, N = 16). We observed that patients with atrophy more often had positive celiac serology (p = 0.019), celiac clinical symptoms (p = 0.018), and iron-deficiency anemia (p = 0.018), but the severity of skin damage was similar in both groups (p = 0.79). At baseline, increased TCRγδ+ cells were present in 94% of patients with atrophy and 67% with non-atrophic lesions (p = 0.13). After a gluten-free diet, increased TCRγδ+ cells persisted in 100% and 63% of cases, respectively (p = 0.21). We concluded that increased TCRγδ+ cells may be helpful in confirming the diagnosis of dermatitis herpetiformis in equivocal cases, even in patients who were started on a gluten-free diet.

Prevalence of non-coeliac gluten sensitivity and assessment of the response to gluten-free diet in a cohort of patients with fibromyalgia

OBJECTIVES

To establish the prevalence of non-coeliac gluten sensitivity (NCGS) in a cohort of fibromyalgia patients and to evaluate their clinical response to a six-week gluten-free diet (GFD), the improvement in their symptoms, the percentage of diet responders who did not fulfil the diagnostic criteria for NCGS and the baseline characteristics that were associated with diet response and diagnostic criteria fulfilment.

METHODS

Uncontrolled prospective experimental study in a cohort of patients with fibromyalgia from a specialized hospital unit. The percentage of patients that fulfilled the Salerno Experts' Criteria, that responded to GFD, that improved their symptomatology and baseline characteristics associated with GFD response and diagnostic criteria fulfilment was analysed.

RESULTS

In total, 142 patients were selected and a NCGS prevalence of 5.6% was observed. A total of 21.8% responded to GFD due to their improvement in intestinal symptoms. In total, 74.2% of the responders did not fulfil the Salerno Experts' Criteria. The presence of diarrhoea and intraepithelial lymphocytosis and lower levels of anxiety were predictive factors of GFD response. No predictive factors of NCGS criteria fulfilment were found due to the low number of discriminators between gluten and placebo.

CONCLUSIONS

A NCGS prevalence similar to that estimated in the general population was found. A GFD cannot be systematically recommended to all patients with fibromyalgia, although it could be evaluated in those with diarrhoea or intraepithelial lymphocytosis to evaluate if there are improvements in their intestinal symptoms.

Intestinal and blood lymphograms as new diagnostic tests for celiac disease

Accurate celiac disease (CD) diagnosis is still challenging for some specific patients or circumstances. Thus, much effort has been expended last decades focused on seronegative or low grade enteropathy CD and, especially, on enable early diagnosis of individuals on a gluten-free diet (GFD). We discuss here two diagnostic approaches based on immunophenotyping by flow cytometry that we expect to reduce the persistent low diagnostic rates and the common diagnostic delay. The intraepithelial lymphogram is based on determining the percentage of TCRγδ+ and surface CD3- lymphocytes in the intestinal epithelium. The concomitant increase in TCRγδ+ and decrease in surface CD3- intraepithelial lymphocytes has been termed the celiac lymphogram and has been proved to be discriminative in seronegative, low grade enteropathy and potential CD, as well as in most CD patients on a GFD. A blood lymphogram based on the analysis of activated gut-homing CD8+ T cells combined with a 3-day gluten challenge is also considered, which has shown high sensitivity and specificity to diagnose seropositive Marsh 1 and Marsh 3 CD in individuals following a GFD. In addition, flow cytometry can be extremely useful in cases of refractory CD type II to identify aberrant cells. Those approaches represent highly accurate methods for CD diagnosis, being simple, fast, highly reproducible and of easy implementation in clinical practice.

Evidence-Based and Emerging Diet Recommendations for Small Bowel Disorders

Diet plays a key role in the manifestation and severity of gastrointestinal symptoms, with increasing research interest on the role of diet in small bowel disorders. There are predominantly 3 small bowel conditions that have potential dietary interventions. Self-reported nonceliac gluten/wheat sensitivity is prevalent. Although gluten is believed to be a potential trigger for symptoms, other components of wheat may also be triggers, including fructans, alpha-amylase trypsin inhibitors, and wheat germ agglutinins. The diagnosis can be challenging, given the lack of validated biomarkers. A gluten-free diet that excludes the abovementioned triggers is the cornerstone of treatment; however, unlike celiac disease, there is uncertainty about the level of adherence or whether the gluten-free diet is a lifelong intervention. Several primary gastrointestinal disorders are associated with an increase in inflammatory cells including eosinophils. Diet seems to be an important driver of disease pathogenesis in eosinophilic gastroenteritis, with elimination and elemental diets showing promise in management, with further robust trials required. Small intestinal bacterial overgrowth is an example of microbial dysbiosis, with renewed interest in diet being postulated to cause an adaptive change of the microbes colonizing the small intestine. However, the diagnosis of small intestinal bacterial overgrowth is limited by a lack of sensitive and specific tests, with significant knowledge gaps in relation to therapeutic measures to manage and cure small intestinal bacterial overgrowth. Currently, antimicrobials are the established management option. There have been significant clinical advances in dietary interventions related to the small bowel, but this area is currently a novel and advancing field for both patients and clinicians.

Effects of a gluten-reduced or gluten-free diet for the primary prevention of cardiovascular disease

BACKGROUND

Cardiovascular diseases (CVD) are a major cause of disability and the leading cause of death worldwide. To reduce mortality and morbidity, prevention strategies such as following an optimal diet are crucial. In recent years, low-gluten and gluten-free diets have gained strong popularity in the general population. However, study results on the benefits of a gluten-reduced or gluten-free diet are conflicting, and it is unclear whether a gluten-reduced diet has an effect on the primary prevention of CVD.

OBJECTIVES

To determine the effects of a gluten-reduced or gluten-free diet for the primary prevention of CVD in the general population.

SEARCH METHODS

We systematically searched CENTRAL, MEDLINE, Embase, CINAHL and Web of Science up to June 2021 without language restrictions or restrictions regarding publication status. Additionally, we searched ClinicalTrials.gov for ongoing or unpublished trials and checked reference lists of included studies as well as relevant systematic reviews for additional studies.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs), such as prospective cohort studies, comparing a low-gluten or gluten-free diet or providing advice to decrease gluten consumption with no intervention, diet as usual, or a reference gluten-intake category. The population of interest comprised adults from the general population, including those at increased risk for CVD (primary prevention). We excluded cluster-RCTs, case-control studies, studies focusing on participants with a previous myocardial infarction and/or stroke, participants who have undergone a revascularisation procedure as well as participants with angina or angiographically-defined coronary heart disease, with a confirmed diagnosis of coeliac disease or with type 1 diabetes.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility of studies in a two-step procedure following Cochrane methods. Risk of bias (RoB) was assessed using the Cochrane risk of bias tool (RoB2) and the 'Risk Of Bias In Non-randomised Studies - of Interventions' (ROBINS-I) tool, and the certainty of evidence was rated using the GRADE approach.

MAIN RESULTS

One RCT and three NRSIs (with an observational design reporting data on four cohorts: Health Professionals Follow-up Study (HPFS), Nurses' Health Study (NHS-I), NHS-II, UK Biobank) met the inclusion criteria. The RCT was conducted in Italy (60 participants, mean age 41 ± 12.1 years), two NRSIs (three cohorts, HPFS, NHS-I, NHS II) were conducted across the USA (269,282 health professionals aged 24 to 75 years) and one NRSI (Biobank cohort) was conducted across the UK (159,265 participants aged 49 to 62 years). Two NRSIs reported that the lowest gluten intake ranged between 0.0 g/day and 3.4 g/day and the highest gluten intake between 6.2 g/day and 38.4 g/day. The NRSI reporting data from the UK Biobank referred to a median gluten intake of 8.5 g/day with an interquartile range from 5.1 g/day to 12.4 g/day without providing low- and high-intake categories. Cardiovascular mortality From a total of 269,282 participants, 3364 (1.3%) died due to cardiovascular events during 26 years of follow-up. Low-certainty evidence may show no association between gluten intake and cardiovascular mortality (adjusted hazard ratio (HR) for low- versus high-gluten intake 1.00, 95% confidence interval (CI) 0.95 to 1.06; 2 NRSIs (3 cohorts)). All-cause mortality From a total of 159,265 participants, 6259 (3.9%) died during 11.1 years of follow-up. Very low-certainty evidence suggested that it is unclear whether gluten intake is associated with all-cause mortality (adjusted HR for low vs high gluten intake 1.00, 95% CI 0.99 to 1.01; 1 NRSI (1 cohort)). Myocardial infarction  From a total of 110,017 participants, 4243 (3.9%) participants developed non-fatal myocardial infarction within 26 years. Low-certainty evidence suggested that gluten intake may not be associated with the development of non-fatal myocardial infarction (adjusted HR for low versus high gluten intake 0.99, 95% CI 0.89 to 1.10; 1 NRSI (2 cohorts)). Lowering gluten intake by 5 g/day also showed no association on the primary prevention of non-fatal and fatal myocardial infarction (composite endpoint) in linear dose-response meta-analyses (adjusted HR 1.02, 95% CI 0.98 to 1.06; 1 NRSI (2 cohorts)). Coronary risk factors  Type 2 diabetes From a total of 202,114 participants, 15,947 (8.0%) developed type 2 diabetes after a follow-up between 22 and 28 years. There was low-certainty evidence that a lower compared with a higher gluten intake may be associated with a slightly increased risk to develop type 2 diabetes (adjusted HR 1.14, 95% CI 1.07 to 1.22; 1 NRSI (3 cohorts)). Furthermore, lowering gluten intake by 5 g/day may be associated with a slightly increased risk to develop type 2 diabetes in linear dose-response meta-analyses (adjusted HR 1.12, 95% CI 1.08 to 1.16; 1 NRSI (3 cohorts)). Blood pressure, low-density lipoprotein level, body mass index (BMI) After six months of follow-up, very low-certainty evidence suggested that it is unclear whether gluten intake affects systolic blood pressure (mean difference (MD) -6.9, 95% CI -17.1 to 3.3 mmHg). There was also no difference between the interventions for diastolic blood pressure (MD -0.8, 95% CI -5.9 to 4.3 mmHg), low-density lipoprotein levels (MD -0.1, 95% CI -0.5 to 0.3 mmol/L) and BMI (MD -0.1, 95% CI -3.3 to 3.1 kg/m²).  No study reported data on adverse events or on other outcomes. Funding sources did not appear to have distorted the results in any of the studies.

AUTHORS' CONCLUSIONS

Very low-certainty evidence suggested that it is unclear whether gluten intake is associated with all-cause mortality. Our findings also indicate that low-certainty evidence may show little or no association between gluten intake and cardiovascular mortality and non-fatal myocardial infarction. Low-certainty evidence suggested that a lower compared with a higher gluten intake may be associated with a slightly increased risk to develop type 2 diabetes - a major cardiovascular risk factor. For other cardiovascular risk factors it is unclear whether there is a difference between a gluten-free and normal diet. Given the limited findings from this review predominantly based on observational studies, no recommendations for practice can be made.

Long-Term Effect of a Gluten-Free Diet on Diarrhoea- or Bloating-Predominant Functional Bowel Disease: Role of the 'Low-Grade Coeliac Score' and the 'Coeliac Lymphogram' in the Response Rate to the Diet

1.

BACKGROUND

The long-term effect of a gluten-free diet (GFD) on functional bowel disorders (FBDs) has been scarcely studied. The aim was to assess the effect of a GFD on FBD patients, and to assess the role of both the low-grade coeliac score and coeliac lymphogram in the probability of response to a GFD. 2.

METHODS

116 adult patients with either predominant diarrhoea or abdominal bloating, fulfilling Rome IV criteria of FBD, were treated with a GFD. Duodenum biopsies were performed for both pathology studies and intraepithelial lymphocyte subpopulation patterns. Coeliac lymphogram was defined as an increase in TCRγδ+ cells plus a decrease in CD3- cells. A low-grade coeliac score >10 was considered positive. 3.

RESULTS

Sustained response to GFD was observed in 72 patients (62%) after a median of 21 months of follow-up, who presented more often with coeliac lymphogram (37.5 vs. 11.4%; p = 0.02) and a score >10 (32 vs. 11.4%; p = 0.027) compared to non-responders. The frequency of low-grade coeliac enteropathy was 19.8%. 4.

CONCLUSION

A GFD is effective in the long-term treatment of patients with previously unexplained chronic watery diarrhoea- or bloating-predominant symptoms fulfilling the criteria of FBD. The response rate was much higher in the subgroup of patients defined by the presence of both a positive low-grade coeliac score and coeliac lymphogram.

Intraepithelial Lymphocyte Cytometric Pattern Is a Useful Diagnostic Tool for Coeliac Disease Diagnosis Irrespective of Degree of Mucosal Damage and Age-A Validation Cohort

Introduction: The study of intraepithelial lymphocytes (IEL) by flow cytometry is a useful tool in the diagnosis of coeliac disease (CD). Previous data showed that an increase in %TCRγδ⁺ and decrease of %CD3⁻ IEL constitute a typical CD cytometric pattern with a specificity of 100%. However, there are no data regarding whether there are differences in the %TCRγδ⁺ related to sex, age, titers of serology, and degree of histological lesion. Study aims: To confirm the high diagnostic accuracy of the coeliac cytometric patterns. To determine if there are differences between sex, age, serology titers, and histological lesion grade. Results: We selected all patients who fulfilled “4 of 5” rule for CD diagnosis (n = 169). There were no differences in %TCRγδ⁺ between sexes (p = 0.909), age groups (p = 0.986), serology titers (p = 0.53) and histological lesion grades (p = 0.41). The diagnostic accuracy of complete CD cytometric pattern was: specificity 100%, sensitivity 82%, PPV 100%, NPV 47%. Conclusion: We confirmed, in a validation cohort, the high diagnostic accuracy of complete CD pattern irrespective of sex, age, serology titers, and grade of mucosal lesion.

Gamma delta+ intraepithelial lymphocytes and coeliac lymphogram in a diagnostic approach to coeliac disease in patients with seronegative villous atrophy

BACKGROUND

The causes of seronegative villous atrophy can be grouped as coeliac or noncoeliac related. There is no consensus on how to approach subjects with seronegative coeliac disease.

AIM

To evaluate the accuracy of both an increase in CD3⁺ T-cell receptor gamma delta⁺ (TCRγδ⁺ ) intraepithelial lymphocytes and coeliac lymphogram for the diagnosis of coeliac disease in patients with seronegative villous atrophy.

METHODS

Sixty-seven consecutive patients with seronegative villous atrophy were included. Duodenal biopsies to assess TCRγδ⁺ and CD3^- by flow cytometry were performed at the index endoscopy. Coeliac lymphogram was defined as an increase in TCRγδ⁺ plus a decrease in CD3^- intraepithelial lymphocytes. Sensitivity, specificity and Fagan's nomogram were calculated.

RESULTS

Coeliac disease was diagnosed in 37 patients and noncoeliac villous atrophy in 30. Coeliac patients were younger (39 ± 3 vs 55 ± 3 years; P = 0.001), more often showed HLA-DQ2/8 (97.6% vs 61%; P = 0.002) and had a more severe histology (61% vs 32% Marsh 3b-c; P = 0.055), as compared to noncoeliac ones. Coeliac lymphogram was associated with a sensitivity of 87% (CI, 73.7-95) and specificity of 96.7% (82.7-99.9), whereas evaluating only TCRγδ⁺ yielded a sensitivity of 91.3% (79.2-97.6) and specificity of 83.3% (65.3-94.3). Among patients with a pre-test coeliac disease probability of 30%, post-test probabilities were 92% and 5% for positive and negative coeliac lymphogram, and 70% and 4% for positive and negative TCRγδ⁺ .

CONCLUSIONS

Coeliac lymphogram was associated with a high level of diagnostic evidence either against or in favour of coeliac disease in patients with seronegative villous atrophy.

Evaluation of Non-Celiac Gluten Sensitivity in Patients with Previous Diagnosis of Irritable Bowel Syndrome: A Randomized Double-Blind Placebo-Controlled Crossover Trial

Background. To date, there is no reliable marker for the diagnosis of non-celiac gluten sensitivity (NCGS), which benefits from a gluten-free diet (GFD). This condition is characterized by functional gastrointestinal symptoms similar to those occurring in the course of irritable bowel syndrome (IBS). However, IBS has a higher prevalence, and often benefits from the administration of a low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet. The overlap of symptoms between these two pathologies has led to an overestimation of self-made diagnosis NCGS. Aims. To better identify NCGS in subjects with a previous diagnosis of IBS. Methods. All subjects received a low FODMAP diet that was also gluten-free (low FODMAP-GFD), and those presenting an improvement of symptoms were exposed to gluten or placebo (double-blind challenge with wash-out and crossover). The response to dietary treatments was evaluated by visual analogue scale (VAS). Results. Of 30 patients (23 women, seven men, aged 42.2 ± 12.5 years, body mass index (BMI ) 24.7 ± 4.1 kg/m2), 26 benefited from the administration of low FODMAP-GFD and were exposed to the gluten/placebo challenge. After the challenge, using an increase of visual analogue scale VAS (Δ-VAS) ≥30%, 46.1% of the patients were NCGS+. However, this percentage became only 19.2% using a different method (mean ∆-VAS score plus two standard deviations). Conclusions. FODMAP intolerance could hide the response to a challenge test with gluten for the identification of NCGS in IBS patients. A low FODMAP-GFD followed by gluten/placebo challenge is able to identify patients with NCGS better. ClinicalTrials.gov registration number NCT04017585.

Incidence and prevalence of self-reported non-coeliac wheat sensitivity and gluten avoidance in Australia

OBJECTIVES

To determine the incidence of self-reported non-coeliac wheat sensitivity (SR-NCWS) and factors associated with its onset and resolution; to describe the prevalence of factors associated with gluten avoidance.

DESIGN

Longitudinal cohort study; analysis of responses to self-administered validated questionnaires (Digestive Health and Wellbeing surveys, 2015 and 2018).

SETTING, PARTICIPANTS

Subset of an adult population sample randomly selected in 2015 from the electoral rolls for the Newcastle and Gosford regions of New South Wales.

MAIN OUTCOME MEASURES

Prevalence of SR-NCWS (2015, 2018) and incidence and resolution of SR-NCWS, each by demographic and medical factors; prevalence of gluten avoidance and reasons for gluten avoidance (2018).

RESULTS

1322 of 2185 eligible participants completed the 2018 survey (response rate, 60.5%). The prevalence of SR-NCWS was similar in 2015 (13.8%; 95% CI, 12.0-15.8%) and 2018 (13.9%; 95% CI, 12.1-15.9%); 69 of 1301 respondents (5.3%) reported developing new onset (incident) SR-NCWS between 2015 and 2018 (incidence, 1.8% per year). Incident SR-NCWS was significantly associated with a diagnosis of functional dyspepsia, and negatively associated with being male or older. Gluten avoidance was reported in 2018 by 24.2% of respondents (20.5% partial, 3.8% complete avoidance); general health was the most frequent reason for avoidance (168 of 316 avoiders, 53%). All 13 participants with coeliac disease, 56 of 138 with irritable bowel syndrome (41%), and 69 of 237 with functional dyspepsia (29%) avoided dietary gluten.

CONCLUSIONS

The prevalence of SR-NCWS was similar in 2015 and 2018. Baseline (2015) and incident SR-NCWS (2018) were each associated with functional gastrointestinal disorders. The number of people avoiding dietary gluten exceeds that of people with coeliac disease or SR-NCWS, and general health considerations and abdominal symptoms are the most frequently reported reasons for avoidance.

Systematic Review and Meta-Analysis: Accuracy of Both Gamma Delta+ Intraepithelial Lymphocytes and Coeliac Lymphogram Evaluated by Flow Cytometry for Coeliac Disease Diagnosis

It has been suggested that in doubtful cases of coeliac disease, a high CD3+ T-cell receptor gamma delta+ (TCRγδ+) intraepithelial lymphocyte count increases the likelihood of coeliac disease.

AIM

To evaluate the diagnostic accuracy of both an isolated increase of TCRγδ+ cells and a coeliac lymphogram (increase of TCRγδ+ plus decrease of CD3- intraepithelial lymphocytes) evaluated by flow cytometry in the diagnosis of coeliac disease.

METHODS

The literature search was conducted in MEDLINE and EMBASE. The inclusion criteria were: an article that allows for the construction of a 2 × 2 table of true and false positive and true and false negative values. A diagnostic accuracy test meta-analysis was performed.

RESULTS

The search provided 49 relevant citations, of which 6 were selected for the analysis, which represented 519 patients and 440 controls. Coeliac lymphogram: The pooled S and Sp were 93% and 98%, without heterogeneity. The area under the SROC curve (AUC) was 0.98 (95% CI, 0.97-0.99). TCRγδ+: Pooled S and Sp were both 95%, with significant heterogeneity. The AUC was 0.97 (95% CI, 0.95-0.98). Conclusions: Both TCRγδ+ count and coeliac lymphogram assessed by flow cytometry in duodenal mucosal samples are associated with a high level of diagnostic accuracy for and against coeliac disease.

Tangible pathologies in functional dyspepsia

Functional dyspepsia (FD) is a common, costly and complex disease, currently defined by symptoms, directed by the Rome consensus on functional bowel disorders, which has evolved over the past two decades. Symptoms include abdominal pain, are often meal related and there are two major subtypes, postprandial distress syndrome and epigastric pain syndrome, not attributed to pathology. Increasingly it is recognised that tangible pathologies occur in FD, for example Helicobacter pylori and other pathophysiological changes, most notably duodenal pathology, namely duodenal eosinophilia, permeability alterations, structural neuronal changes and microbial duodenal dysbiosis. This has led to the idea that FD is a true disease entity and triggers of this condition based on epidemiology studies point towards allergy, immune disorders and infection. Anxiety and depression may precede or follow FD, (brain-gut/gut-brain disorders). Currently most therapies for FD are inadequate but underlying pathology may lead to targeted treatment success as an attainable goal.

Non-Celiac Gluten Sensitivity: A Review

Background and objectives: Grain food consumption is a trigger of gluten related disorders: celiac disease, non-celiac gluten sensitivity (NCGS) and wheat allergy. They demonstrate with non-specific symptoms: bloating, abdominal discomfort, diarrhea and flatulence. Aim: The aim of the review is to summarize data about pathogenesis, symptoms and criteria of NCGS, which can be helpful for physicians. Materials and Methods: The PubMed and Google Scholar databases were searched in January 2019 with phrases: 'non-celiac gluten sensitivity', non-celiac gluten sensitivity', non-celiac wheat gluten sensitivity', non-celiac wheat gluten sensitivity', and gluten sensitivity'. More than 1000 results were found. A total of 67 clinical trials published between 1989 and 2019 was scanned. After skimming abstracts, 66 articles were chosen for this review; including 26 clinical trials. Results: In 2015, Salerno Experts' Criteria of NCGS were published. The Salerno first step is assessing the clinical response to gluten free diet (GFD) and second is measuring the effect of reintroducing gluten after a period of treatment with GFD. Several clinical trials were based on the criteria. Conclusions: Symptoms of NCGS are similar to other gluten-related diseases, irritable bowel syndrome and Crohn's disease. With Salerno Experts' Criteria of NCGS, it is possible to diagnose patients properly and give them advice about nutritional treatment.

A Scoring System for Identifying Patients Likely to Be Diagnosed with Low-Grade Coeliac Enteropathy

BACKGROUND & AIMS

Determining whether patients with lymphocytic enteritis (LE) have coeliac disease is a challenge. We analysed the variables associated with a low-grade coeliac enteropathy diagnosis in patients with suspected coeliac disease but without villous atrophy, and developed a scoring system to identify them.

METHODS

We collected data from 2010 through to 2016 on patients with lymphocytic enteritis and persistent symptoms compatible with the clinical spectrum of coeliac disease. One hundred and four patients starting on a gluten-free diet (GFD) were included. Duodenal biopsies were collected before the GFD and analysed for numbers of CD3⁺ T-cell receptor gamma delta+ (TCRγδ⁺), and CD3^- intraepithelial lymphocytes. We performed a logistic regression analysis to identify factors associated with a low-grade coeliac enteropathy diagnosis.

RESULTS

Sixty-two patients achieved clinical remission after the GFD. Fifty of these 62 patients were diagnosed with low-grade coeliac enteropathy. Multivariate analysis identified the presence of >25% intraepithelial lymphocytosis, HLA-DQ2.5, positive serology, and increased numbers of TCRγδ⁺ cells with a low-grade coeliac enteropathy diagnosis. We developed a scoring system that identified patients with an area under the ROC curve (AUC) of 0.91. Scores of >10 had 86% sensitivity and 85% specificity.

CONCLUSION

We developed a scoring system that identifies patients likely to be diagnosed with low-grade coeliac enteropathy with an AUC value of 0.91.

The overlap of irritable bowel syndrome and noncoeliac gluten sensitivity

PURPOSE OF REVIEW

There has been significant interest in gluten over the last decade, with an increase in interest of gluten-related disorders outside coeliac disease. Particularly, there has been a focus on the role of gluten in noncoeliac gluten sensitivity (NCGS) and irritable bowel syndrome (IBS). There is significant overlap between both of these conditions, with the aim of this review to explore their complex relationship.

RECENT FINDINGS

Gluten has been demonstrated to generate symptoms in individuals with NCGS. However, there appears to be an increasing role for gluten in symptom generation in patients with IBS also. Other components of wheat, other than gluten, are now also thought to be contributing factors in symptom generation.

SUMMARY

There appears to be significant overlap between IBS and NCGS. It is likely that a subset of patients presenting with IBS actually have NCGS. In addition, it is likely that individuals with IBS may also have symptoms triggered by gluten. With the pathophysiology of both conditions not fully understood, as well as increasing knowledge of wheat components in symptom generation, further research is required to help distinguish between both.

Gluten Vehicle and Placebo for Non-Celiac Gluten Sensitivity Assessment

Non-celiac gluten sensitivity (NCGS) is a syndrome characterized by gastrointestinal and extraintestinal manifestations triggered after gluten ingestion in the absence of celiac disease and wheat allergy. Because of the lack of biomarkers for NCGS diagnosis, the cornerstone for its assessment is a single- or double-blind placebo-controlled (DBPC) gluten challenge. However, there are some non-standardized points in the diagnostic approach proposed by the experts. This complicate comparisons among the results published by different research groups. The gluten vehicle and placebo must be indistinguishable from each other, which entails sensory and technological evaluations of the designed gluten vehicle and placebo products. At the moment, there is no standardized method for the preparation of the gluten vehicle and placebo for carrying out DBPC gluten challenges for NCGS assessment. This review focuses on the challenges that researchers have to face, either for the development of an accepted gluten vehicle and placebo or for identifying NCGS cases on the basis of DBPC gluten challenges.

Exposure to Different Amounts of Dietary Gluten in Patients with Non-Celiac Gluten Sensitivity (NCGS): An Exploratory Study

It is unclear whether patients with non-celiac gluten sensitivity (NCGS) can tolerate gluten. We have evaluated the changes of both gastrointestinal symptoms and quality of life for NCGS patients after the re-introduction of dietary gluten. Twenty-two NCGS patients reporting functional gastroenterological symptoms and on gluten-free diet (GFD) for the previous three weeks were exposed to incremental gluten-containing diets. Three groups were compared at baseline (immediately after 3-weeks on GFD) and immediately after the return of symptomatology: (i) a group tolerating a low-gluten diet (3.5 g gluten/day, week 1, n = 8), (ii) a group tolerating a mid-gluten diet (8 g gluten/day, week 2, n = 6), and (iii) a group tolerating a high-gluten diet (13 g gluten/day, week 3, n = 8). Their gastrointestinal symptoms and quality of life were assessed at baseline and post-intervention. The most common symptoms were: constipation (46%), abdominal pain (50%) and dyspepsia (38%). A decrease in several short form health survey (SF-36) sub-scores (all p < 0.03) after gluten re-introduction was only observed in the group tolerating the low-gluten diet; the same group showed a lower post-intervention role-emotional SF-36 score (p = 0.01). Most gastrointestinal symptoms remained similar after gluten re-introduction. However, a decrease in the general perception of well-being was only found after gluten re-introduction in the group tolerating a low-gluten diet (p = 0.01); the same was true when comparing the post-intervention general well-being perception among the three groups (p = 0.050). In conclusion, dissimilar responses from patients with NCGS were observed after the re-introduction of gluten, with gluten at a low dosage affecting the quality of life and general well-being of a group of patients, whereas others tolerate even higher doses of dietary gluten.

Case-finding in primary care for coeliac disease: Accuracy and cost-effectiveness of a rapid point-of-care test

Background

An on-site, rapid, fingertip, whole-blood point-of-care test (POCT) is attractive for active case-finding of coeliac disease (CD) in primary care because of its simplicity.

Aim

The aim of this article is to assess the usefulness and cost-effectiveness of adult case-finding using a POCT based on deamidated gliadin peptide antibodies (IgA/IgG-DGP) in primary care for CD diagnosis.

Methods

A case-finding study for CD was conducted by using an easy-to-use, on-site, whole-blood for IgA/IgG-DGP-based fingertip POCT compared with tTG2 in 350 individuals. Sample size was calculated based on 0.28% prevalence in the reference population. Duodenal biopsies for histology, intraepithelial lymphocytes and in situ deposition of tTG2 were obtained if tTG2 and/or POCT were positive. Accuracy and cost-effectiveness of strategies using serology or POCT were calculated.

Results

Prevalence of CD was 1.14% (95% CI, 0.3–3.4), almost double what was previously observed. Four patients were diagnosed with CD. tTG2 was positive in three (0.85%) and POCT in 29 (8.2%). Sensitivity of POCT for CD was 100%, specificity 93%, PPV 14%, and NPV 100%. POCT followed by duodenal biopsy was the most cost-effective approach in our setting (standard diagnosis: €13,033/case; POCT + duodenal biopsy: €7360/case).

Conclusions

A negative POCT allows ruling out CD in primary care, making it suitable for case-finding. POCT strategy was the most cost effective.

A New Proposal for the Pathogenic Mechanism of Non-Coeliac/Non-Allergic Gluten/Wheat Sensitivity: Piecing Together the Puzzle of Recent Scientific Evidence

Non-coeliac/non-allergic gluten/wheat sensitivity (NCG/WS) is a gluten-related disorder, the pathogenesis of which remains unclear. Recently, the involvement of an increased intestinal permeability has been recognized in the onset of this clinical condition. However, mechanisms through which it takes place are still unclear. In this review, we attempt to uncover these mechanisms by providing, for the first time, an integrated vision of recent scientific literature, resulting in a new hypothesis about the pathogenic mechanisms involved in NCG/WS. According to this, the root cause of NCG/WS is a particular dysbiotic profile characterized by decreased butyrate-producing-Firmicutes and/or Bifidobacteria, leading to low levels of intestinal butyrate. Beyond a critical threshold of the latter, a chain reaction of events and vicious circles occurs, involving other protagonists such as microbial lipopolysaccharide (LPS), intestinal alkaline phosphatase (IAP) and wheat α-amylase trypsin inhibitors (ATIs). NCG/WS is likely to be a multi-factor-onset disorder, probably transient and preventable, related to quality and balance of the diet, and not to the presence of gluten in itself. If future studies confirm our proposal, this would have important implications both for the definition of the disease, as well as for the prevention and therapeutic-nutritional management of individuals with NCG/WS.

Non-coeliac gluten or wheat sensitivity: emerging disease or misdiagnosis?

Non-coeliac gluten or wheat sensitivity (NCG/WS) is a condition characterised by adverse gastrointestinal and/or extra-intestinal symptoms associated with the ingestion of gluten- or wheat-containing foods, in the absence of coeliac disease or wheat allergy. Up to one in 100 people in Australia may have coeliac disease but many more report adverse gastrointestinal and/or extra-intestinal symptoms after eating wheat products. In the absence of validated biomarkers, a diagnosis of NCG/WS can only be made by a double-blind, placebo-controlled, dietary crossover challenge with gluten, which is difficult to apply in clinical practice. Of people self-reporting gluten or wheat sensitivity, only a small proportion (16%) will have reproducible symptoms after a blinded gluten challenge of gluten versus placebo in a crossover dietary trial and fulfil the current consensus criteria for a diagnosis of NCG/WS. A wide range of symptoms are associated with NCG/WS, including gastrointestinal, neurological, psychiatric, rheumatological and dermatological complaints. The pathogenesis of NCG/WS is not well understood, but the innate immune system has been implicated, and there is overlap with coeliac disease and the functional gastrointestinal disorders (irritable bowel syndrome and functional dyspepsia). Identification of NCG/WS is important as gluten-free diets carry risks, are socially restricting and are costlier than regular diets.

Re-challenge Studies in Non-celiac Gluten Sensitivity: A Systematic Review and Meta-Analysis

Background: Non-celiac gluten sensitivity (NCGS) is a clinical entity characterized by intestinal and/or extra-intestinal symptoms related to the ingestion of gluten in individuals that are not affected by either celiac disease (CD) or wheat allergy (WA). Since we do not have specific biomarkers for NCGS, the diagnosis is based on the evidence of a clear relationship between the ingestion of gluten (re-challenge) and clinical symptoms, after a remission during the gluten-free diet (GFD). Several re-challenge studies have been published so far to evaluate the real prevalence of NCGS, reporting conflicting results. In the present article, we provide a systematic review with meta-analysis of the existing literature on re-challenge studies to evaluate prevalence figures of NCGS after re-challenge procedures. Methods: All clinical trials performing a gluten re-challenge with or without a placebo control in patients with a suspected diagnosis of NCGS were included. Search results were limited to studies published in English language. No publication date or publication status restrictions were imposed. Results: Eleven studies were included in the meta-analysis. There was a considerable heterogeneity related to different sample size, type, and amount of gluten administered, duration of challenge and different type of placebo. The overall pooled percentage of patients with a diagnosis of NCGS relapsing after a gluten challenge was 30%, ranging between 7 and 77%. The meta-analysis showed a not significant relative risk (RR) of relapse after gluten challenge as compared to placebo (RR = 0.4; 95% CI = -0.15-0.9; p = 0.16). The overall pooled percentage of patients with a diagnosis of NCGS relapsing after a gluten challenge performed according to the recent Salerno criteria was significantly higher as compared to the percentage of patients relapsing after placebo (40 vs. 24%; p = 0.003), with a significant RR of relapse after gluten challenge as compared to placebo (RR = 2.8; 95% CI = 1.5-5.5; p = 0.002). Conclusions: The prevalence of NCGS after gluten re-challenge is low, and the percentage of relapse after a gluten or a placebo challenge is similar. However, a higher number of patients will be correctly classified with NCGS if applying the recent Salerno criteria.

Non-coeliac gluten/wheat sensitivity: advances in knowledge and relevant questions

Non-coeliac gluten/wheat sensitivity (NCG/WS) is a syndrome characterized by intestinal and extra-intestinal symptoms occurring a few hours or days after the ingestion of gluten and wheat proteins in patients testing negative for coeliac disease and wheat allergy. Areas covered: The present review deals with recent scientific acquisitions of this gluten-related syndrome, including pathogenetic mechanisms, clinical picture, symptom score, biomarkers and double-blind placebo-controlled trial for diagnosis, and treatment. The methodology used was a literature search on NCG/WS using Medline and Premedline from 1970 to August 2016. Expert commentary: We discussed the pathogenesis of symptom generation and altered gut physiology in NCG/WS. Possible mechanisms include innate and adaptive immune activation, impaired intestinal epithelial barrier and changes in gut microbiome. These interlinked factors may be exploited for their clinical relevance as possible biomarkers. A systemic immune response to microbial and wheat antigens, together with intestinal cell damage, occurs in patients with NCG/WS. Due to the lack of established biomarkers, it is mandatory to validate the diagnosis of the syndrome by means of a well-defined work-up involving dietary challenge. Finally, dietary and other therapeutic indications have been thoroughly reviewed.