Deamidation and Enzymatic Hydrolysis of Gliadins Alter Their Processing by Dendritic Cells in Vitro

Abstract

Gliadins are major wheat allergens. Their treatment by acid or enzymatic hydrolysis has been shown to modify their allergenic potential. As the interaction of food proteins with dendritic cells (DCs) is a key event in allergic sensitization, we wished to investigate whether deamidation and enzymatic hydrolysis influence gliadin processing by DC and to examine the capacity of gliadins to activate DCs. We compared the uptake and degradation of native and modified gliadins by DCs using mouse bone marrow-derived DCs. We also analyzed the effects of these interactions on the phenotypes of DCs and T helper (Th) lymphocytes. Modifying gliadins induced a change in physicochemical properties (molecular weight, hydrophobicity, and sequence) and also in the peptide size. These alterations in turn led to increased uptake and intracellular degradation of the proteins by DCs. Native gliadins (NGs) (100 μg/mL), but not modified gliadins, increased the frequency of DC expressing CD80 (15.41 ± 2.36% vs 6.81 ± 1.10%, p < 0.001), CCR7 (28.53 ± 8.17% vs 17.88 ± 2.53%, p < 0.001), CXCR4 (70.14 ± 4.63% vs 42.82 ± 1.96%, p < 0.001), and CCR7-dependent migration (2.46 ± 1.45 vs 1.00 ± 0.22, p < 0.01) compared with NGs. This was accompanied by Th lymphocyte activation (30.37 ± 3.87% vs 21.53 ± 3.14%, p < 0.1) and proliferation (16.39 ± 3.97% vs 9.31 ± 2.80%, p > 0.1). Moreover, hydrolysis decreases the peptide size and induces an increase in gliadin uptake and degradation. Deamidation and extensive enzymatic hydrolysis of gliadins modify their interaction with DCs, leading to alteration of their immunostimulatory capacity. These findings demonstrate the strong relationship between the biochemical characteristics of proteins and immune cell interactions.

Acid Hydrolysis of Gluten Enhances the Skin Sensitizing Potential and Drives Diversification of IgE Reactivity to Unmodified Gluten Proteins

“…Gluten samples were dissolved (5 mg mL −1 ) in 0.1 M sodium phosphate buffer (137 mM NaCl, 2.7 mM KCl, 10 mM Na 2 HPO 4 , 1.76 mM KH 2 PO 4 , pH 6.9) with 2% (v:v) SDS at 60 °C overnight on a rotary shaker. Native gliadin, purified as previously described, [29,30] was included as a positive control. SDS-soluble proteins were obtained after centrifugation at 7500 × g for 10 min.…”

“…[33,34] Briefly, ELISA plates were coated with the highly deamidated LQPEEPFPEQC peptide conjugated to BSA, with deamidated 𝛼-gliadins, [35] or with native gliadins. [29,30] Gluten samples were pre-incubated with antibodies Mab INRA-DG1, [33] MAb MCO1, [36] and MAb PQQ3B4 [37] directed respectively against the high, low, or nondeamidated epitopes and subsequently added to plates. Antibody binding to coated plates was detected using horseradish peroxidase (HRP)-labeled anti-mouse IgG (170-6516, Bio-Rad).…”

Allergenicity of Deamidated and/or Peptide-Bond-Hydrolyzed Wheat Gliadin by Transdermal Administration

“…The enhancement of basophils in HWP-sensitized patients was reported to be induced by HWP administration [39]. Moreover, HCl-treated gliadin increased degradation by bone marrow-derived dendritic cells [40]. We evaluated the sensitizing property of each gliadin by measuring the activities of basophils and dendritic cells.…”

Protein deamidation to produce processable ingredients and engineered colloids for emerging food applications

“…These functional particles display a variety of properties suitable for novel applications, such as product structuring and the delivery of bioactives (Wang et al., 2019a; Wang et al., 2019b; Xiang et al., 2018). Moreover, deamidated proteins have been confirmed to show changed bioactivity, varied digestibility, and altered allergenicity (Cui et al., 2013; Qiu et al., 2013; Villemin et al., 2020), which provide both opportunities and challenges for their food applications.…”