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Biochem Biophys Res Commun. 2014 Aug 8;450(4):1247-54. doi: 10.1016/j.bbrc.2014.06.101. Epub 2014 Jul 7.

Cleavage of the terminal N-acetylglucosamine of egg-white ovalbumin N-glycans significantly reduces IgE production and Th2 cytokine secretion.

Author information

1
Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 221 Huksuk-dong, Dongjak-ku, Seoul 156-756, South Korea.
2
Department of Food and Nutrition, Yuhan College, Bucheon 422-749, South Korea.
3
Functional Materials Research Group, Korea Food Research Institute, Seongnam 463-746, South Korea.
4
Functional Materials Research Group, Korea Food Research Institute, Seongnam 463-746, South Korea. Electronic address: chdon@kfri.re.kr.
5
Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 221 Huksuk-dong, Dongjak-ku, Seoul 156-756, South Korea. Electronic address: hahyung@cau.ac.kr.

Abstract

Ovalbumin (OA) is one of the most abundant of the glycoprotein allergens, and induces a T-helper type 2 immune response that results in an IgE-mediated hypersensitivity. In this study, the terminal carbohydrates of N-glycans from intact OA were cleaved with the exoglycosidases galactosidase, mannosidase, and N-acetylglucosaminidase to generate degalactosylated-OA, demannosylated-OA, and de-N-acetylglucosaminylated-OA, respectively, in order to evaluate their role in allergenicity. The exoglycosidase digestion procedure did not result in either degradation or contamination of the three deglycosylated sample, and the digestion efficiency was confirmed by comparing the results of glycan analysis of the three exoglycosidase-treated OAs with that of glycans of intact OA. Mice were immunized with either intact or exoglycosidase-treated OAs, and their respective allergic reactions were compared. IgE production in the de-N-acetylglucosaminylated-OA group was reduced to 58.8% of that in the intact OA group. In addition, the production levels of the cytokines interleukin-4 and interleukin-5 were significantly reduced in the de-N-acetylglucosaminylated-OA group to 53.4% and 45.8% of the levels in the intact OA group, respectively. However, there were almost no changes (or only slight reductions) in the degalactosylated-OA and demannosylated-OA groups, respectively. These results indicate that cleavage of the terminal carbohydrate, and particularly N-acetylglucosamine, reduces the allergenicity of OA. This is the first report of the effect of cleavage of the terminal carbohydrate on glycoprotein allergenicity.

KEYWORDS:

Allergenicity; IgE production; Ovalbumin; Terminal carbohydrate; Th2-type cytokines

PMID:
25010643
DOI:
10.1016/j.bbrc.2014.06.101
[Indexed for MEDLINE]
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