Basophil Activation to Gluten and Non-Gluten Proteins in Wheat-Dependent Exercise-Induced Anaphylaxis

Abstract

Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a cofactor-induced wheat allergy. Gluten proteins, especially ω5-gliadins, are known as major allergens, but partially hydrolyzed wheat proteins (HWPs) also play a role. Our study investigated the link between the molecular composition of gluten or HWP and allergenicity. Saline extracts of gluten (G), gluten with reduced content of ω5-gliadins (G-ω5), slightly treated HWPs (sHWPs), and extensively treated HWPs (eHWPs) were prepared as allergen test solutions and their allergenicity assessed using the skin prick test and basophil activation test (BAT) on twelve patients with WDEIA and ten controls. Complementary sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), high-performance liquid chromatography (HPLC), and mass spectrometry (MS) analyses revealed that non-gluten proteins, mainly α-amylase/trypsin inhibitors (ATIs), were predominant in the allergen test solutions of G, G-ω5, and sHWPs. Only eHWPs contained gliadins and glutenins as major fraction. All allergen test solutions induced significantly higher %CD63+ basophils/anti-FcεRI ratios in patients compared with controls. BAT using sHWPs yielded 100% sensitivity and 83% specificity at optimal cut-off and may be useful as another tool in WDEIA diagnosis. Our findings indicate that non-gluten proteins carrying yet unidentified allergenic epitopes appear to be relevant in WDEIA. Further research is needed to clarify the role of nutritional ATIs in WDEIA and identify specific mechanisms of immune activation.

Detection of Sensitization Profiles with Cellular In Vitro Tests in Wheat Allergy Dependent on Augmentation Factors (WALDA)

“…Nonetheless, other gluten allergens such as highmolecular-weight glutenin subunits (HMW-GS), along with potential cross-reactivity to other cereals, may be of relevance for these patients as well [1,[8][9][10]. Additionally, recently, nongluten proteins like α-amylase/trypsin inhibitors (ATI) have also been hypothesized to be relevant in WALDA [11].…”

Breeding from 1891 to 2010 did not increase the content of amylase/trypsin-inhibitors in wheat (Triticum aestivum)

“…The term NCWS is used for individuals who report intestinal or extra-intestinal complaints, other than related to celiac disease or classical wheat allergy 2 , 6 . Apart from gluten proteins, amylase/trypsin-inhibitors (ATIs) are known allergens in bakers’ asthma 7 and may play a role in wheat-dependent exercise-induced anaphylaxis 8 . Moreover, ATIs activate the toll-like receptor 4 TLR4-MD2-CD14 complex on intestinal monocytes-macrophages and dendritic cells causing their activation and secretion of proinflammatory chemokines and cytokines 9 , 10 .…”

Molecular allergology and its application in prevention, diagnosis and therapy

“… The Basophil Activation Test (BAT) provides information on the presence of allergen specific IgE and cellular activation and degranulation ( 16 ). Due to the activation of basophils by allergen extracts or specific allergens, upregulation of surface marker expression can be measured and allows to assess the onset of an allergic reaction ( 41 , 42 ). BAT assays can be performed using either patient-derived cells or by applying a standardized cell population from a given donor.…”

“…In specialized centers BAT is already included in daily diagnosis of allergies. Especially for peanut and sesame allergy a BAT assay is recommended if other test results remain inconclusive ( 9 , 41 , 42 ). Wheat dependent exercise-induced anaphylaxis (WDEIA) is a co-factor induced wheat allergy and considered to be a rare disease.…”

“…Using this approach they could identify gluten and additional non-gluten proteins from wheat as allergens relevant for WDEIA. This approach may improve the diagnosis of this disease and help to rule out idiopathic anaphylaxis for these patients ( 41 ). Recently, BAT tests have been shown to be helpful in another IgE mediated disease, ABPA, allergic bronchopulmonary aspergillosis.…”