Effect of in vitro gastric and duodenal digestion on the allergenicity of grape lipid transfer protein.
ABSTRACT Severe grape allergy has been linked to lipid transfer protein (LTP) sensitization. LTPs are known to be resistant to pepsin digestion, although the effect of gastroduodenal digestion on its allergenicity has not been reported.
We sought to investigate the effect of gastric and gastroduodenal digestion on the allergenic activity of grape LTP.
The proteolytic stability of grape LTP was investigated by using an in vitro model of gastrointestinal digestion. The allergenicity of LTP and its digesta was assessed in vitro by means of IgE immunoblotting, RASTs, and in vivo skin prick tests in the same patients with grape allergy.
Grape LTP was resistant to gastric digestion, and yielded a 6000-d relative molecular mass C-terminally trimmed fragment after duodenal digestion. This fragment retained the in vitro IgE reactivity of the intact protein. Inclusion of phosphatidylcholine during gastric digestion protected the LTP to a limited extent against digestion. Digestion did not affect the in vivo (skin prick test) biologic activity of LTP.
The allergenic activity of grape LTP was highly resistant to in vitro digestion. This property might facilitate sensitization through the gastrointestinal tract and might also potentiate the ability of LTPs to elicit severe allergic reactions in sensitized individuals.
Purified natural allergens will facilitate the development of component-resolved diagnostic approaches, including allergen chips. This study contributes to our understanding of the role digestion plays in symptom elicitation in true food allergy.
- SourceAvailable from: Sun Jin Hur
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ABSTRACT: Besides its antimicrobial properties, lysozyme (LYS) is one of the major allergens from hen egg. This paper addresses the identification of the peptides produced upon in vitro gastrointestinal digestion of LYS, together with their IgE-binding and biological activity as a contribution to the understanding of what makes it a relevant allergen. Simulated in vitro gastrointestinal digestion together with IgE binding, basophil degranulation, and peripheral blood mononuclear cells stimulation experiments were carried out. Identification of the fragments released was performed by HPLC-MS/MS and the immunoreactive products were analyzed by MALDI-TOF/TOF. Results showed that in vitro gastric and gastroduodenal digests of LYS maintained IgE binding, basophil activation capacity, and preserved T-cell immunogenicity. These biological activities could be attributed to either the persistence of intact LYS, due to incomplete gastric degradation and subsequent duodenal precipitation, the formation of fragment f(24-129) by chymotrypsin action on the soluble intact protein, or the release, upon combined gastric and pancreatic digestion, of immunoreactive peptides linked by disulphide bonds containing the epitopes f(57-83) and f(108-122). The pH of gastric hydrolysis greatly determined the extent of subsequent duodenal digestion of LYS and the disclosure of relevant epitopes that could increase its allergenic potential.Molecular Nutrition & Food Research 10/2013; · 4.31 Impact Factor
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ABSTRACT: Allergic sensitization is a multifactorial process that is not only influenced by the allergen and its biological function per se but also by other small molecular compounds, such as lipids, that are directly bound as ligands by the allergen or are present in the allergen source. Several members of major allergen families bind lipid ligands through hydrophobic cavities or electrostatic or hydrophobic interactions. These allergens include certain seed storage proteins, Bet v 1-like and nonspecific lipid transfer proteins from pollens and fruits, certain inhalant allergens from house dust mites and cockroaches, and lipocalins. Lipids from the pollen coat and furry animals and the so-called pollen-associated lipid mediators are codelivered with the allergens and can modulate the immune responses of predisposed subjects by interacting with the innate immune system and invariant natural killer T cells. In addition, lipids originating from bacterial members of the pollen microbiome contribute to the outcome of the sensitization process. Dietary lipids act as adjuvants and might skew the immune response toward a TH2-dominated phenotype. In addition, the association with lipids protects food allergens from gastrointestinal degradation and facilitates their uptake by intestinal cells. These findings will have a major influence on how allergic sensitization will be viewed and studied in the future.The Journal of allergy and clinical immunology. 05/2014;