Effect of malondialdehyde on the ovalbumin structure and its interactions with T84 epithelial cells

Abstract

Background: Protein oxidation can occur as a consequence of lipid peroxidation during food processing. The aim of this work was to explore the effect of malondialdehyde (MDA) modification of ovalbumin (OVA) on its interaction with T84 intestinal cells. Methods: Molecular dynamics simulation was employed for the prediction of MDA modification in the OVA, while introduced structural changes were evaluated by measurement of carbonyl group content, fluorescence spectra, MS/MS analysis, and IgE reactivity. Effects of MDA modified OVA on T84 epithelial cells were analyzed by gene expression for pro-inflammatory cytokines and protein secretion. Results: Out of 9 predicted, five modified Lys residues were confirmed by MS/MS analysis: (51)TQINKVVR(58), (85)DILNQITKPNDVYSFSLASR(104), (111)YPILPEYLQCVKELYR(126), (187)AFKDEDTQAMPFR(99), (KIKVYLPR284)-K-277, and (IKVYLPR284)-I-278. The introduced MDA modifications influenced profile of IgE reactivity to OVA. Treatment of T84 epithelial cells with OVA and OVA modified with 1 mM MDA, induced up-regulation of pro-inflammatory cytokines (IL-1 beta,IL-25, IL-33, TSLP and TNF alpha), while OVA modification with 10 mM MDA induced down regulation of the cytokine expression profile, except for IL-1 beta. OVA and OVA modified with 1 mM MDA induced secretion of epithelial cells specific cytokine IL-33. Conclusions: This finding indicated that OVA and its MDA modified form have the potential to trigger the innate immunity by inducing up-regulation and secretion of pro-allergenic IL-33 in T84 intestinal epithelial cells. General significance: Interactions of ovalbumin and its MDA modified form with intestinal epithelial cells can induce a specific immunological priming necessary for the downstream activation of innate immunity.