Intake and sources of gluten in 20- to 75-year-old Danish adults: a national dietary survey

Thin-Plate Superstructures of the Immunogenic 33-mer Gliadin Peptide

Gluten related-disorders have a prevalence of 1-5 % worldwide triggered by the ingestion of gluten proteins in wheat, rye, barley, and some oats. In wheat gluten, the most studied protein is gliadin, whose immunodominant 33-mer amino acid fragment remains after digestive proteolysis and accumulates in the gut mucosa. Here, we report the formation of 33-mer thin-plate superstructures using intrinsic tyrosine (Tyr) steady-state fluorescence anisotropy and cryo-TEM in combination with water tension measurements. Furthermore, we showed that fluorescence decay measurements of 33-mer intrinsic fluorophore Tyr provided information on the early stages of the formation of the thin-plate structures. Finally, conformational analysis of Tyr residues using minimalist models by molecular dynamic simulations (MD) demonstrated that changes in Tyr rotamer states depend on the oligomerization stage. Our findings further advance the understanding of the formation of the 33-mer gliadin peptide superstructures and their relation to health and disease.

Randomised controlled trial: effects of gluten-free diet on symptoms and the gut microenvironment in irritable bowel syndrome

BACKGROUND

A gluten-free diet reduces symptoms in some patients with irritable bowel syndrome (IBS) through unclear mechanisms.

AIMS

To assess the effects of gluten-free versus gluten-containing diet on symptoms and the gut microenvironment, and to identify predictors of response to the gluten-free diet in IBS METHODS: Twenty patients with IBS and 18 healthy controls (HC) followed a gluten-free diet during two 14-day intervention periods where they sprinkled either gluten (14 g/day) or rice flour powder over their meals. Primary outcomes included effects of the interventions on IBS symptoms (IBS-SSS) and bowel habits. Secondary outcomes included effects of gluten-free diet on faecal microbiota and metabolite profile.

RESULTS

IBS symptoms improved during the gluten-free (p = 0.02), but not the gluten-containing period, with no difference between the interventions. IBS patients reported fewer loose stools during the gluten-free intervention (p = 0.01). Patients with IBS and HC presented distinct metabolite profiles based on the effects of the gluten-free diet (p < 0.001). True responders (reduced IBS-SSS by ≥50 solely after gluten-free period) and non-responders were discriminated based on the effects of the gluten-free diet on the microbiota (p < 0.01) and metabolite profiles (p < 0.001). The response to the gluten-free diet could be predicted by the metabolite profile before the intervention (p < 0.001).

CONCLUSIONS

A gluten-free diet may influence symptoms in a subset of patients with IBS, with a particular effect on bowel habits. A gluten-free diet seems to impact the gut microenvironment. Responsiveness to the gluten-free diet may be predicted by the metabolite profile.

CLINICALTRIALS

gov: NCT03869359.

Review article: Follow-up of coeliac disease

Coeliac disease is a lifelong immune-mediated enteropathy with systemic features associated with increased morbidity and modestly increased mortality. Treatment with a strict gluten-free diet improves symptoms and mucosal damage but is not curative and low-level gluten intake is common despite strict attempts at adherence. Regular follow-up after diagnosis is considered best-practice however this is executed poorly in the community with the problem compounded by the paucity of data informing optimal approaches. The aim of dietary treatment is to resolve symptoms, reduce complication risk and improve quality of life. It follows that the goals of monitoring are to assess dietary adherence, monitor disease activity, assess symptoms and screen for complications. Mucosal disease remission is regarded a key measure of treatment success as healing is associated with positive health outcomes. However, persistent villous atrophy is common, even after many years of a gluten-free diet. As the clinical significance of asymptomatic enteropathy is uncertain the role for routine follow-up biopsies remains contentious. Symptomatic non-responsive coeliac disease is common and with systematic follow-up a cause is usually found. Effective models of care involving the gastroenterologist, dietitian and primary care doctor will improve the consistency of long-term management and likely translate into better patient outcomes. Identifying suitable treatment targets linked to long-term health is an important goal.

The effect of gluten in adolescents and young adults with gastrointestinal symptoms: a blinded randomised cross-over trial

BACKGROUND

The popularity of the gluten-free diet and sales of gluten-free products have increased immensely.

AIMS

To investigate whether gluten induces gastrointestinal symptoms, measured by self-reported questionnaires, as well as mental health symptoms in adolescents from a population-based cohort.

METHODS

The eligible participants (n = 273) were recruited from a population-based cohort of 1266 adolescents and had at least four different gastrointestinal symptoms. Phase one (n = 54) was a run-in phase where the participants lived gluten-free for 2 weeks. If they improved they continued to phase 2 (n = 33), a blinded randomised cross-over trial. Participants were blindly randomised either to start with 7 days of gluten, eating two granola bars containing 10 g of gluten or to 7 days on placebo, eating two granola bars without gluten, followed by the reverse and separated by a 7-day washout period. The effects of the intervention on gastrointestinal symptoms and mental health symptoms were assessed.

RESULTS

In total, 54/273 participants entered the run-in phase and 35 were eligible for randomization. A total of 33 were randomised and 32 completed the trial. The median age was 20.3 (IQR 19.2-20.9) and 32/33 participants were females. Compared with a placebo, gluten did not induce gastrointestinal symptoms. The difference in the average VAS was -0.01 (95% confidence interval -2.07 to 2.05). Nor did we find a difference in the outcomes measuring mental health.

CONCLUSION

Compared with placebo, adding gluten to the diet did not induce gastrointestinal symptoms or worsened mental health in adolescents recruited from a population-based cohort. The trial registration number is NCT04639921.

Plasma IL-2 and Symptoms Response after Acute Gluten Exposure in Subjects With Celiac Disease or Nonceliac Gluten Sensitivity

INTRODUCTION

Treated patients with celiac disease (CeD) and nonceliac gluten sensitivity (NCGS) report acute, transient, incompletely understood symptoms after suspected gluten exposure. To determine whether (i) blinded gluten exposure induces symptoms, (ii) subjects accurately identify gluten exposure, and (iii) serum interleukin-2 (IL-2) levels distinguish CeD from NCGS subjects after gluten exposure.

METHODS

Sixty subjects (n = 20 treated, healed CeD; n = 20 treated NCGS; n = 20 controls) were block randomized to a single, double-blind sham (rice flour) or 3-g gluten challenge with 72-hours follow-up. Twelve serial questionnaires (100 mm visual analog scale; pain, bloating, nausea, and fatigue) and 10 serial plasma samples were collected. Mucosal permeability was assessed using both urinary lactulose-13C mannitol ratios and endoscopic mucosal impedance.

RESULTS

Thirty-five of 40 (83%) subjects with CeD and NCGS reported symptoms with gluten (8 CeD, 9 NCGS) and sham (9 CeD, 9 NCGS) compared with 9 of 20 (45%) controls after gluten (n = 6) and sham (n = 3). There was no significant difference in symptoms among groups. Only 2 of 10 subjects with CeD and 4 of 10 NCGS identified gluten, whereas 8 of 10 subjects with CeD and 5 of 10 NCGS identified sham. A significant plasma IL-2 increase occurred only in subjects with CeD after gluten, peaking at 3 hours and normalizing within 24 hours postchallenge despite no significant intestinal permeability change from baseline.

DISCUSSION

Symptoms do not reliably indicate gluten exposure in either subjects with CeD or NCGS. IL-2 production indicates a rapid-onset gluten-induced T-cell activation in CeD despite long-standing treatment. The effector site is unknown, given no increased intestinal permeability after gluten.

Gluten and fructan intake and their associations with gastrointestinal symptoms in irritable bowel syndrome: A food diary study

BACKGROUND & AIMS

Wheat contains several components, including gluten and fructan, that may be associated with gastrointestinal symptoms (GI) in irritable bowel syndrome (IBS). The aims of the study were to determine the average daily intake of gluten, investigate the association of gluten and GI symptoms, as well as the association between fructan and GI symptoms in IBS subjects.

METHODS

We assessed dietary intake, including total energy, and calculated average gluten and fructan intake in this 4-day food diary study. The subjects reported GI symptoms using the validated Gastrointestinal Symptom Rating Scale-IBS (GSRS-IBS).

RESULTS

In total, 147 IBS subjects (116 females) were included in this study. The median (IQR) intake of gluten was 11.0 (7.5-15.4) (range: 0.6-52.1) g/day, and this intake was significantly higher for males (16.2 (11.5-18.8), g/day) compared with females (10.3 (7.3-13.2), g/day) (P ≤ 0.001). For analyses purposes, the subjects were stratified in tertiles of gluten intake. Median (IQR) overall GI symptom severity (GSRS-IBS) was significantly worse for the subjects with the lowest (52 (45-57)) and intermediate gluten intake (51 (43-58)), compared with the highest gluten intake (45 (37-50), P ≤ 0.05, and P ≤ 0.01 respectively). In addition, caloric intake was significantly lower in subjects with the lowest (1905 ± 446, kcal/day) and intermediate gluten intake (1854 ± 432, kcal/day), compared with subjects with the highest gluten intake (2305 ± 411, kcal/day), P < 0.001 for both. Analyses of the stratified fructan tertiles resulted in no significant differences in GSRS-IBS.

CONCLUSIONS

The mean intake of gluten varies substantially among subjects with IBS, and IBS subjects with more severe GI symptoms have lower intake of gluten and calories.

TRIAL REGISTRY

(http://www.clinicaltrials.gov): Registered under Clinical Trial number NCT02970591.

Celiac Disease: Fallacies and Facts

Our understanding of the pathophysiology of celiac disease has progressed greatly over the past 25 years; however, some fallacies about the clinical characteristics and management persist. Worldwide epidemiologic data are now available showing that celiac disease is ubiquitous. An elevated body mass index is common at the time of the diagnosis. The gluten-free diet (GFD) is an imperfect treatment for celiac disease; not all individuals show a response. This diet is widely used by people without celiac disease, and symptomatic improvement on a GFD is not sufficient for diagnosis. Finally, the GFD is burdensome, difficult to achieve, and thus has an incomplete efficacy, opening exciting opportunities for novel, nondietary treatments.

Gluten intake and metabolic health: conflicting findings from the UK Biobank

PURPOSE

The impact of gluten intake on metabolic health in subjects without celiac disease is unclear. The present study aimed to assess the association between gluten intake and body fat percentage (primary objective), as well as a broad set of metabolic health markers.

METHODS

Gluten intake was estimated in 39,927 participants of the UK Biobank who completed a dietary questionnaire for assessment of previous 24-h dietary intakes. Multiple linear regression analyses were performed between gluten intake and markers of metabolic health with Holm adjustment for multiple comparisons.

RESULTS

Median gluten intake was 9.7 g/day (male: 11.7 g/day; female: 8.2 g/day; p < 0.0001). In multiple linear regression analysis, association between gluten intake and percentage body fat was negative in males (β = - 0.028, p = 0.0020) and positive in females (β = 0.025, p = 0.0028). Furthermore, gluten intake was a negative predictor of total cholesterol (male: β = - 0.031, p = 0.0154; female: β = - 0.050, p < 0.0001), high-density lipoprotein cholesterol (male: β = - 0.052, p < 0.0001; female: β = - 0.068, p < 0.0001), and glomerular filtration rate (sexes combined: β = - 0.031, p < 0.0001) in both sexes. In females only, gluten intake was positively associated with waist circumference (β = 0.041, p < 0.0001), waist-to-height ratio (β = 0.040, p < 0.0001), as well as body mass index (β = 0.043, p < 0.0001), and negatively related to low-density lipoprotein cholesterol (β = - 0.035, p = 0.0011). A positive association between gluten intake and triglycerides was observed in males only (β = 0.043, p = 0.0001).

CONCLUSION

This study indicates that gluten intake is associated with markers of metabolic health. However, all associations are weak and not clinically meaningful. Limiting gluten intake is unlikely to provide metabolic health benefits for a population in total.

Serum cytokines elevated during gluten-mediated cytokine release in coeliac disease

Cytokines have been extensively studied in coeliac disease, but cytokine release related to exposure to gluten and associated symptoms has only recently been described. Prominent, early elevations in serum interleukin (IL)-2 after gluten support a central role for T cell activation in the clinical reactions to gluten in coeliac disease. The aim of this study was to establish a quantitative hierarchy of serum cytokines and their relation to symptoms in patients with coeliac disease during gluten-mediated cytokine release reactions. Sera were analyzed from coeliac disease patients on a gluten free-diet (n = 25) and from a parallel cohort of healthy volunteers (n = 25) who underwent an unmasked gluten challenge. Sera were collected at baseline and 2, 4 and 6 h after consuming 10 g vital wheat gluten flour; 187 cytokines were assessed. Confirmatory analyses were performed by high-sensitivity electrochemiluminescence immunoassay. Cytokine elevations were correlated with symptoms. Cytokine release following gluten challenge in coeliac disease patients included significant elevations of IL-2, chemokine (C-C motif) ligand 20 (CCL20), IL-6, chemokine (C-X-C motif) ligand (CXCL)9, CXCL8, interferon (IFN)-γ, IL-10, IL-22, IL-17A, tumour necrosis factor (TNF)-α, CCL2 and amphiregulin. IL-2 and IL-17A were earliest to rise. Peak levels of cytokines were generally at 4 h. IL-2 increased most (median 57-fold), then CCL20 (median 10-fold). Cytokine changes were strongly correlated with one another, and the most severely symptomatic patients had the highest elevations. Early elevations of IL-2, IL-17A, IL-22 and IFN-γ after gluten in patients with coeliac disease implicates rapidly activated T cells as their probable source. Cytokine release after gluten could aid in monitoring experimental treatments and support diagnosis.

Gluten Intake and Risk of Celiac Disease: Long-Term Follow-up of an At-Risk Birth Cohort

OBJECTIVES

To determine the association between the amount of gluten intake in childhood and later celiac disease (CD), for which data are currently scarce.

METHODS

The prospective Diabetes Autoimmunity Study in the Young cohort includes 1875 at-risk children with annual estimates of gluten intake (grams/d) from age 1 year. From 1993 through January 2017, 161 children, using repeated tissue transglutaminase (tTGA) screening, were identified with CD autoimmunity (CDA) and persistent tTGA positivity; of these children, 85 fulfilled CD criteria of biopsy-verified histopathology or persistently high tTGA levels. Cox regression, modeling gluten intake between ages 1 and 2 years (i.e., in 1-year-olds), and joint modeling of cumulative gluten intake throughout childhood were used to estimate hazard ratios adjusted for confounders (aHR).

RESULTS

Children in the highest third of gluten intake between the ages of 1 and 2 years had a 2-fold greater hazard of CDA (aHR 2.17; 95% confidence interval [CI], 1.22-3.88; P value = 0.01) and CD (aHR 1.96; 95% CI, 0.90-4.24; P value = 0.09) than those in the lowest third. The risk of developing CDA increased by 5% per daily gram increase in gluten intake (aHR 1.05; 95% CI, 1.00-1.09; P value = 0.04) in 1-year-olds. The association between gluten intake in 1-year-olds and later CDA or CD did not differ by the child's human leukocyte antigen genotype. The incidence of CD increased with increased cumulative gluten intake throughout childhood (e.g., aHR 1.15 per SD increase in cumulative gluten intake at age 6; 95% CI, 1.00-1.32; P value = 0.04).

DISCUSSION

Gluten intake in 1-year-olds is associated with the future onset of CDA and CD in children at risk for the disease.

Gluten Intake and Risk of Islet Autoimmunity and Progression to Type 1 Diabetes in Children at Increased Risk of the Disease: The Diabetes Autoimmunity Study in the Young (DAISY)

OBJECTIVE

To study the association of gluten intake with development of islet autoimmunity and progression to type 1 diabetes.

RESEARCH DESIGN AND METHODS

The Diabetes Autoimmunity Study in the Young (DAISY) follows children with an increased risk of type 1 diabetes. Blood samples were collected at 9, 15, and 24 months of age, and annually thereafter. Islet autoimmunity was defined by the appearance of at least one autoantibody against insulin, IA2, GAD, or ZnT8 (zinc transporter 8) in at least two consecutive blood samples. Using food frequency questionnaires, we estimated the gluten intake (in grams per day) annually from 1 year of age. Cox regression modeling early gluten intake, and joint modeling of the cumulative gluten intake during follow-up, were used to estimate hazard ratios adjusted for confounders (aHR).

RESULTS

By August 2017, 1,916 subjects were included (median age at end of follow-up 13.5 years), islet autoimmunity had developed in 178 participants, and 56 of these progressed to type 1 diabetes. We found no association between islet autoimmunity and gluten intake at 1-2 years of age or during follow-up (aHR per 4 g/day increase in gluten intake 1.00, 95% CI 0.85-1.17 and 1.01, 0.99-1.02, respectively). We found similar null results for progression from islet autoimmunity to type 1 diabetes. Introduction of gluten at <4 months of age was associated with an increased risk of progressing from islet autoimmunity to type 1 diabetes compared with introduction at 4-5.9 months (aHR 8.69, 95% CI 1.69-44.8).

CONCLUSIONS

Our findings indicate no strong rationale to reduce the amount of gluten in high-risk children to prevent development of type 1 diabetes.

A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults

Adherence to a low-gluten diet has become increasingly common in parts of the general population. However, the effects of reducing gluten-rich food items including wheat, barley and rye cereals in healthy adults are unclear. Here, we undertook a randomised, controlled, cross-over trial involving 60 middle-aged Danish adults without known disorders with two 8-week interventions comparing a low-gluten diet (2 g gluten per day) and a high-gluten diet (18 g gluten per day), separated by a washout period of at least six weeks with habitual diet (12 g gluten per day). We find that, in comparison with a high-gluten diet, a low-gluten diet induces moderate changes in the intestinal microbiome, reduces fasting and postprandial hydrogen exhalation, and leads to improvements in self-reported bloating. These observations suggest that most of the effects of a low-gluten diet in non-coeliac adults may be driven by qualitative changes in dietary fibres.

Gluten-free diets are increasingly common in the general population. Here, the authors report the results of a randomised cross-over trial involving middle-aged, healthy Danish adults, showing evidence that a low-gluten diet leads to gut microbiome changes, possibly due to variations in dietary fibres.

Gluten intake and risk of type 2 diabetes in three large prospective cohort studies of US men and women

AIMS/HYPOTHESIS

We investigated the association between gluten intake and long-term type 2 diabetes risk among Americans.

METHODS

We followed women from the Nurses' Health Study (NHS, n = 71,602, 1984-2012) and NHS II (n = 88,604, 1991-2013) and men from the Health Professionals Follow-Up Study (HPFS, n = 41,908, 1986-2012). Gluten intake was estimated using a validated food frequency questionnaire every 2-4 years. Incident type 2 diabetes was defined as self-reported physician-diagnosed diabetes confirmed using a supplementary questionnaire.

RESULT

Gluten intake was strongly correlated with intakes of carbohydrate components, especially refined grains, starch and cereal fibre (Spearman correlation coefficients >0.6). During 4.24 million years of follow-up, 15,947 people were confirmed to have type 2 diabetes. After multivariate adjustment, pooled HRs and 95% CIs for type 2 diabetes, from low to high gluten quintiles, were (p_trend < 0.001): 1 (reference); 0.89 (0.85, 0.93); 0.84 (0.80, 0.88); 0.78 (0.74, 0.82) and 0.80 (0.76, 0.84). The association was slightly weakened after further adjusting for cereal fibre, with pooled HRs (95% CIs) of (p_trend < 0.001): 1 (reference); 0.91 (0.87, 0.96); 0.88 (0.83, 0.93); 0.83 (0.78, 0.88) and 0.87 (0.81, 0.93). Dose-response analysis supported a largely linear inverse relationship between gluten intake up to 12 g/day and type 2 diabetes. The association between gluten intake and type 2 diabetes was stronger when intake of added bran was also higher (p_interaction = 0.02).

CONCLUSIONS/INTERPRETATION

Gluten intake is inversely associated with type 2 diabetes risk among largely healthy US men and women. Limiting gluten in the diet is associated with lower intake of cereal fibre and possibly other beneficial nutrients that contribute to good health.

Association between maternal gluten intake and type 1 diabetes in offspring: national prospective cohort study in Denmark

OBJECTIVE

To examine the association between prenatal gluten exposure and offspring risk of type 1 diabetes in humans.

DESIGN

National prospective cohort study.

SETTING

National health information registries in Denmark.

PARTICIPANTS

Pregnant Danish women enrolled into the Danish National Birth Cohort, between January 1996 and October 2002, MAIN OUTCOME MEASURES: Maternal gluten intake, based on maternal consumption of gluten containing foods, was reported in a 360 item food frequency questionnaire at week 25 of pregnancy. Information on type 1 diabetes occurrence in the participants' children, from 1 January 1996 to 31 May 2016, were obtained through registry linkage to the Danish Registry of Childhood and Adolescent Diabetes.

RESULTS

The study comprised 101 042 pregnancies in 91 745 women, of whom 70 188 filled out the food frequency questionnaire. After correcting for multiple pregnancies, pregnancies ending in abortions, stillbirths, lack of information regarding the pregnancy, and pregnancies with implausibly high or low energy intake, 67 565 pregnancies (63 529 women) were included. The average gluten intake was 13.0 g/day, ranging from less than 7 g/day to more than 20 g/day. The incidence of type 1 diabetes among children in the cohort was 0.37% (n=247) with a mean follow-up period of 15.6 years (standard deviation 1.4). Risk of type 1 diabetes in offspring increased proportionally with maternal gluten intake during pregnancy (adjusted hazard ratio 1.31 (95% confidence interval 1.001 to 1.72) per 10 g/day increase of gluten). Women with the highest gluten intake versus those with the lowest gluten intake (≥20 v <7 g/day) had double the risk of type 1 diabetes development in their offspring (adjusted hazard ratio 2.00 (95% confidence interval 1.02 to 4.00)).

CONCLUSIONS

High gluten intake by mothers during pregnancy could increase the risk of their children developing type 1 diabetes. However, confirmation of these findings are warranted, preferably in an intervention setting.

Determination of gluten consumption in celiac disease patients on a gluten-free diet

Background

Celiac disease (CD) patients adhering to a gluten-free diet (GFD) are exposed frequently to low levels of gluten that contribute to symptoms and persistent intestinal histologic damage.

Objective

We analyzed prior clinical data to determine how much gluten is accidentally consumed while on a GFD. The aim was to understand the range of gluten consumption for a wide distribution of CD patients.

Design

A meta-analysis was conducted on data from 2 different clinical programs: 1) measurements of gluten in stool and urine in CD and non-CD populations; and 2) analysis of data from trials for the investigational therapeutic latiglutenase. The stool and urine studies included controlled gluten challenges. A calibration factor was applied that allowed normal ingestion of gluten to be computed from the urine and stool measurements. From the latiglutenase trial data, a determination of gluten consumption was made by estimating how much gluten was eliminated from patients' diets due to a trial effect that led to improved histology even in the placebo group.

Results

The average inadvertent exposure to gluten by CD individuals on a GFD was estimated to be ∼150-400 (mean) and ∼100-150 (median) mg/d using the stool test and ∼300-400 (mean) and ∼150 (median) mg/d using the urine test. The analyses of the latiglutenase data for CD individuals with moderate to severe symptoms indicate that patients ingested significantly >200 mg/d of gluten.

Conclusions

These surrogate biomarkers of gluten ingestion indicate that many individuals following a GFD regularly consume sufficient gluten to trigger symptoms and perpetuate intestinal histologic damage.

Epitope-Specific Immunotherapy Targeting CD4-Positive T Cells in Celiac Disease: Safety, Pharmacokinetics, and Effects on Intestinal Histology and Plasma Cytokines with Escalating Dose Regimens of Nexvax2 in a Randomized, Double-Blind, Placebo-Controlled Phase 1 Study

BACKGROUND

Nexvax2® is a novel, peptide-based, epitope-specific immunotherapy intended to be administered by regular injections at dose levels that increase the threshold for clinical reactivity to natural exposure to gluten and ultimately restore tolerance to gluten in patients with celiac disease. Celiac disease patients administered fixed intradermal doses of Nexvax2 become unresponsive to the HLA-DQ2·5-restricted gluten epitopes in Nexvax2, but gastrointestinal symptoms and cytokine release mimicking gluten exposure, that accompany the first dose, limit the maximum tolerated dose to 150μg. Our aim was to test whether stepwise dose escalation attenuated the first dose effect of Nexvax2 in celiac disease patients.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial at four community sites in Australia (3) and New Zealand (1) in HLA-DQ2·5 genotype positive adults with celiac disease who were on a gluten-free diet. Participants were assigned to cohort 1 if they were HLA-DQ2·5 homozygotes; other participants were assigned to cohort 2, or to cohort 3 subsequent to completion of cohort 2. Manual central randomization without blocking was used to assign treatment for each cohort. Initially, Nexvax2-treated participants in cohorts 1 and 2 received an intradermal dose of 30μg (consisting of 10μg of each constituent peptide), followed by 60μg, 90μg, 150μg, and then eight doses of 300μg over six weeks, but this was amended to include doses of 3μg and 9μg and extended over a total of seven weeks. Nexvax2-treated participants in cohort 3 received doses of 3μg, 9μg, 30μg, 60μg, 90μg, 150μg, 300μg, 450μg, 600μg, 750μg, and then eight of 900μg over nine weeks. The dose interval was 3 or 4days. Participants, care providers, data managers, sponsor personnel, and study site personnel were blinded to treatment assignment. The primary outcome was the number of adverse events and percentage of participants with adverse events during the treatment period. This completed trial is registered with ClinicalTrials.gov, number NCT02528799.

FINDINGS

From the 73 participants who we screened from 19 August 2015 to 31 October 2016, 24 did not meet eligibility criteria, and 36 were ultimately randomized and received study drug. For cohort 1, seven participants received Nexvax2 (two with the starting dose of 30μg and then five at 3μg) and three received placebo. For cohort 2, 10 participants received Nexvax2 (four with starting dose of 30μg and then six at 3μg) and four received placebo. For cohort 3, 10 participants received Nexvax2 and two received placebo. All 36 participants were included in safety and immune analyses, and 33 participants completed treatment and follow-up; in cohort 3, 11 participants were assessed and included in pharmacokinetics and duodenal histology analyses. Whereas the maximum dose of Nexvax2 had previously been limited by adverse events and cytokine release, no such effect was observed when dosing escalated from 3μg up to 300μg in HLA-DQ2·5 homozygotes or to 900μg in HLA-DQ2.5 non-homozygotes. Adverse events with Nexvax2 treatment were less common in cohorts 1 and 2 with the starting dose of 3μg (72 for 11 participants) than with the starting dose of 30μg (91 for six participants). Adverse events during the treatment period in placebo-treated participants (46 for nine participants) were similar to those in Nexvax2-treated participants when the starting dose was 3μg in cohort 1 (16 for five participants), cohort 2 (56 for six participants), and cohort 3 (44 for 10 participants). Two participants in cohort 2 and one in cohort 3 who received Nexvax2 starting at 3μg did not report any adverse event, while the other 33 participants experienced at least one adverse event. One participant, who was in cohort 1, withdrew from the study due to adverse events, which included abdominal pain graded moderate or severe and associated with nausea after receiving the starting dose of 30μg and one 60μg dose. The most common treatment-emergent adverse events in the Nexvax2 participants were headache (52%), diarrhoea (48%), nausea (37%), abdominal pain (26%), and abdominal discomfort (19%). Administration of Nexvax2 at dose levels from 150μg to 900μg preceded by dose escalation was not associated with elevations in plasma cytokines at 4h. Nexvax2 treatment was associated with trends towards improved duodenal histology. Plasma concentrations of Nexvax2 peptides were dose-dependent.

INTERPRETATION

We show that antigenic peptides recognized by CD4-positive T cells in an autoimmune disease can be safely administered to patients at high maintenance dose levels without immune activation if preceded by gradual dose escalation. These findings facilitate efficacy studies that test high-dose epitope-specific immunotherapy in celiac disease.

What is gluten?

Gluten is the main storage protein of wheat grains. Gluten is a complex mixture of hundreds of related but distinct proteins, mainly gliadin and glutenin. Similar storage proteins exist as secalin in rye, hordein in barley, and avenins in oats and are collectively referred to as "gluten." The objective was to discuss the biochemical and functional properties of the gluten proteins, including structure, sources, and dietary intakes. Literature was reviewed from food science and nutrition journals. The gluten protein networks vary because of different components and sizes, and variability caused by genotype, growing conditions, and technological processes. The structures and interactions of this matrix contribute to the unique properties of gluten. The resulting functions are essential to determining the dough quality of bread and other baked products. Gluten is heat stable and has the capacity to act as a binding and extending agent and is commonly used as an additive in processed foods for improved texture, moisture retention, and flavor. Gliadin contains peptide sequences that are highly resistant to gastric, pancreatic, and intestinal proteolytic digestion in the gastrointestinal tract. The average daily gluten intake in a Western diet is thought to be 5-20 g/day and has been implicated in several disorders. Gluten containing grains (wheat, rye, barley, and oats) are important staple foods. Gluten is among the most complex protein networks and plays a key role in determining the rheological dough properties.