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Farnell EJ, Tyagi N, Ryan S, Chalmers IW, Pinot de Moira A, Jones FM, Wawrzyniak J, Fitzsimmons CM, Tukahebwa EM, Furnham N, Maizels RM, Dunne DW. Known Allergen Structures Predict Schistosoma mansoni IgE-Binding Antigens in Human Infection. Front Immunol 2015; 6:26. [PMID: 25691884 PMCID: PMC4315118 DOI: 10.3389/fimmu.2015.00026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 01/12/2015] [Indexed: 12/21/2022] Open
Abstract
The IgE response has been associated with both allergic reactions and immunity to metazoan parasites. Recently, we hypothesized that all environmental allergens bear structural homology to IgE-binding antigens from metazoan parasites and that this homology defines the relatively small number of protein families containing allergenic targets. In this study, known allergen structures (Pfam domains) from major environmental allergen families were used to predict allergen-like (SmProfilin, SmVAL-6, SmLipocalin, SmHSP20, Sm triosephosphate isomerase, SmThioredoxin, Sm superoxide dismutase, SmCyclophilin, and Sm phosphoglycerate kinase) and non-allergen-like [Sm dynein light chain (SmDLC), SmAldolase SmAK, SmUbiquitin, and Sm14-3-3] proteins in Schistosoma mansoni. Recombinant antigens were produced in Escherichia coli and IgG1, IgG4, and IgE responses against them measured in a cohort of people (n = 222) infected with S. mansoni. All allergen-like antigens were targeted by IgE responses in infected subjects, whilst IgE responses to the non-allergen-like antigens, SmAK, SmUbiquitin, and Sm14-3-3 were essentially absent being of both low prevalence and magnitude. Two new IgE-binding Pfam domain families, not previously described in allergen family databases, were also found, with prevalent IgE responses against SmDLC (PF01221) and SmAldolase (PF00274). Finally, it was demonstrated that immunoregulatory serological processes typically associated with allergens also occurred in responses to allergen-like proteins in S. mansoni infections, including the production of IgG4 in people responding with IgE and the down-regulation of IgE in response to increased antigen exposure from S. mansoni eggs. This study establishes that structures of known allergens can be used to predict IgE responses against homologous parasite allergen-like molecules (parallergens) and that serological responses with IgE/IgG4 to parallergens mirror those seen against allergens, supporting our hypothesis that allergenicity is rooted in expression of certain protein domain families in metazoan parasites.
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Affiliation(s)
- Edward J Farnell
- Department of Pathology, University of Cambridge , Cambridge , UK
| | - Nidhi Tyagi
- European Bioinformatics Institute , Cambridge , UK
| | - Stephanie Ryan
- Institute of Immunology and Infection Research, The University of Edinburgh , Edinburgh , UK
| | - Iain W Chalmers
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University , Aberystwyth , UK
| | | | - Frances M Jones
- Department of Pathology, University of Cambridge , Cambridge , UK
| | - Jakub Wawrzyniak
- Department of Pathology, University of Cambridge , Cambridge , UK
| | | | | | - Nicholas Furnham
- European Bioinformatics Institute , Cambridge , UK ; Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine , London , UK
| | - Rick M Maizels
- Institute of Immunology and Infection Research, The University of Edinburgh , Edinburgh , UK
| | - David W Dunne
- Department of Pathology, University of Cambridge , Cambridge , UK
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