Recombinant Culicoides obsoletus complex allergens stimulate antigen-specific T cells of insect bite hypersensitive Shetland ponies in vitro.
BACKGROUND
Ponies may suffer from Insect bite hypersensitivity (IBH), an allergic IgE-mediated pruritic skin disorder, induced by allergens from biting midges of the Culicoides spp.


OBJECTIVE
To determine whether recombinant Culicoides obsoletus allergens are able to activate T cells of ponies exposed to C. obsoletus and whether these allergen-specific responses differ between IBH-affected and healthy ponies.


METHODS
Ten IBH-affected Shetland ponies and 10 age-matched healthy controls taken from the same stables, to ensure similar exposure to midges.


METHODS
Peripheral blood mononuclear cells (PBMC) were cultured with two different pools of recombinant C. obsoletus complex allergens to expand the allergen-specific T cells. These PBMC cultures were subsequently co-cultured with mature dendritic cells (DCs) loaded with the same antigens. Induction of Th1, Th2 and regulatory T (Treg) cells in these DC/PBMC co-cultures was assessed by analysis of IFN-γ, IL-4, IL-10 and FoxP3 expression levels using quantitative RT-PCR and phenotyping by flow cytometry.


RESULTS
Recombinant C. obsoletus allergens increased IFN-γ mRNA expression levels, percentages of IFN-γ expressing (Th1) cells and CD25(high) FoxP3(+) IL-10(+) Tregs compared to unstimulated DC/PBMC co-cultures. Stimulation of IL-4 expressing Th2 cells by the recombinant allergens was far less pronounced. The DC/PBMC co-cultures did not reveal significant differences between healthy and IBH-affected ponies for any of the analysed parameters, except for higher IL-4 mRNA levels in IBH affected ponies after stimulation with one of the two allergen pools.


CONCLUSIONS
The recombinant C. obsoletus complex allergens can stimulate antigen-specific Th1 and IL10 producing Treg cells and are therefore promising candidates for the immunotherapy of IBH.
Division of Immunology, Department of Infectious Diseases & Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, Utrecht, 3584 CL, the Netherlands.
Chantal
C
Meulenbroeks
Cell Biology and Immunology group, Wageningen University, De Elst 1, Wageningen, 6708 WD, the Netherlands.
Nathalie M A
NM
van der Meide
Division of Immunology, Department of Infectious Diseases & Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, Utrecht, 3584 CL, the Netherlands.|Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 108, Utrecht, 3584 CM, the Netherlands.
Ton
T
Willemse
Division of Immunology, Department of Infectious Diseases & Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, Utrecht, 3584 CL, the Netherlands.|Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
Victor P M G
VP
Rutten
Cell Biology and Immunology group, Wageningen University, De Elst 1, Wageningen, 6708 WD, the Netherlands.
Edwin
http://orcid.org/0000-0002-9014-0407
E
Tijhaar
D000485:Allergens / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002519:Ceratopogonidae / Q000378:metabolism*; D005786:Gene Expression Regulation; D006734:Horse Diseases / Q000276:immunology* / Q000378:metabolism; D006736:Horses; D006967:Hypersensitivity / Q000276:immunology / Q000662:veterinary*; D007299:Insect Bites and Stings / Q000276:immunology / Q000662:veterinary*; D007371:Interferon-gamma; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D013601:T-Lymphocytes / Q000378:metabolism*
D000485:Allergens; D012333:RNA, Messenger; D011994:Recombinant Proteins; D007371:Interferon-gamma