Elevated serum interleukin‐2 after gluten correlates with symptoms and is a potential diagnostic biomarker for coeliac disease

Abstract

Summary Background Coeliac disease patients on a gluten‐free diet experience reactions to gluten, but these are not well characterised or understood. Systemic cytokine release was recently linked to reactivation of gluten immunity in coeliac disease. Aim To define the nature and time‐course of symptoms and interleukin‐2 changes specific for coeliac disease patients. Methods 25 coeliac disease patients on a gluten‐free diet and 25 healthy volunteers consumed a standardised 6 gram gluten challenge. Coeliac Disease Patient‐Reported Outcome survey and global digestive symptom assessment were completed hourly up to 6 hours after gluten. Adverse events over 48 hours were recorded. Serum interleukin‐2 was measured at baseline, and 2, 4 and 6 hours. Results Serum interleukin‐2 was always undetectable in healthy controls, whereas it was undetectable at baseline and elevated >0.5 pg/ml at 4 hours in 92% of coeliac disease patients. All patient‐reported outcome severity scores increased significantly after gluten in coeliac disease patients (P < .001 Wilcoxon signed rank test), but not in controls. Symptoms began after 1 hour, and peaked in the third. Nausea and vomiting characterised severe reactions, but mild reactions were limited to headache and tiredness. Peak interleukin‐2 correlated with symptom severity, particularly for nausea and vomiting. Conclusions Serum interleukin‐2 elevations correlate with timing and severity of symptoms after gluten in coeliac disease. Standardised bolus gluten food challenge and interleukin‐2 assessment could provide a valuable clinical test to monitor and diagnose coeliac disease in patients established on a gluten‐free diet.

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

“…personalized assessment of immune activation that was correlated with patient-reported outcome data. The present study complements two companion reports that describe assessments limited to only IL-2 in the same set of sera assessed in this study using a formally qualified electrochemiluminescence assay performed by a third-party vendor under good laboratory conditions [14,15]. IL-2 levels were always below the lower limit of quantitation (0·5 pg/ml) at all time-points in the healthy volunteers and also at baseline in the coeliac disease patients, but 23 of the 25 coeliac disease patients had elevated IL-2 levels 4 h after gluten [14,15].…”

“…The present study complements two companion reports that describe assessments limited to only IL-2 in the same set of sera assessed in this study using a formally qualified electrochemiluminescence assay performed by a third-party vendor under good laboratory conditions [14,15]. IL-2 levels were always below the lower limit of quantitation (0·5 pg/ml) at all time-points in the healthy volunteers and also at baseline in the coeliac disease patients, but 23 of the 25 coeliac disease patients had elevated IL-2 levels 4 h after gluten [14,15]. Unlike ex-vivo or in-vitro assays with gluten-stimulated fresh blood cells, intestinal tissue, or particularly T cell lines and clones, cytokine assessments in serum are unlikely to be prone to significant laboratory artefact and, at least for IL-2, IL-8 and IL-10, appear to be consistent findings after injection of deamidated gluten peptides and for food challenges with 3 or 6 g of gluten protein, and gluten ingested in a variety of formats, such as bread or as vital gluten added cooked in muesli bars, or uncooked in the format used in the present study [1].…”

“…Sera and clinical data collected in volunteers with coeliac disease during an unmasked gluten food challenge on the first day of screening for the 'Nexvax2-1005' study (NCT03543540) were reassessed along with matching sera and data from an identical unmasked gluten food challenge performed in a parallel study in healthy adults. Truitt et al have reported the Nexvax2-1005 study in detail elsewhere, and Tye-Din et al reported a detailed account of symptoms associated with the unmasked food challenge, which included prespecified IL-2 assessments during gluten challenge that were performed separately from the present study [14,15]. Briefly, the first cohort consisted of all 25 patients diagnosed with coeliac disease who enrolled and completed screening procedures at their first visit.…”

Baseline quantitative histology in therapeutics trials reveals villus atrophy in most patients with coeliac disease who appear well controlled on gluten‐free diet

“…In the three phase 1 studies, which have been reported in detail elsewhere, patients with coeliac disease were maintaining their usual gluten‐free diet had no study interventions before their pre‐treatment biopsy. In the phase 2 (‘RESET CeD’) trial, which has also been described elsewhere, patients with coeliac disease were maintaining their usual gluten‐free diet, but had a single bolus gluten challenge (6 g of gluten protein taken as 10 g vital wheat gluten flour in water) 3 weeks before biopsy collection according to the protocol described by Tye‐Din et al…”

Patient factors influencing acute gluten reactions and cytokine release in treated coeliac disease

“…These include nocebo effects, where patient's negative expectations to potential gluten exposure influence their symptoms and the presence of non-gluten dietary components such as fermentable carbohydrates (FODMAPs) that can cause symptoms of irritable bowel syndrome (IBS) independent of gluten [4,5]. In several recent gluten food challenge studies in small groups of patients with treated CD, unmasked and also double-blind, sham-controlled gluten challenges designed to be low in FODMAPs cause significant worsening of nausea, sometimes with vomiting, within 2-h and peak at 3 to 4 h, but rarely caused diarrhoea [6,7]. This acute symptomatic reaction to gluten in patients with treated CD is linked to significant concomitant elevations in serum cytokines, which are not observed in individuals without CD or those with self-reported non-CD gluten sensitivity [7][8][9].…”