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Frontiers in immunology2025; 16; 1597233; doi: 10.3389/fimmu.2025.1597233

Culicoides allergens expressed in insect cells induce sulphidoleukotriene release from peripheral blood leukocytes of horses affected with insect bite hypersensitivity.

Abstract: Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis in horses caused by bites of spp. The allergens are salivary gland proteins from these insects, and nine major allergens from have been identified and expressed in . However, proteins expressed in procaryotic systems have limitations in cellular assays, particularly in functional assays assessing the allergen-induced release of mediators , such as sulphidoleukotrienes (sLT) from basophils. The aims of the study were to produce functional allergens in insect cells, to assess their allergenicity using a sLT release assay, and to relate the sLT release with IgE sensitization to the respective allergens using ELISA. Unassigned: Eight major allergens (Cul o 1P, Cul o 2P, Cul o 3, Cul o 5, Cul o 7, Cul o 8, Cul o 9, and Cul o 11) were expressed in insect cells and purified. sLT release from peripheral blood leukocytes (PBL) following stimulation with the eight allergens was measured in 28 IBH-affected and 24 healthy control horses. Allergen-specific serum IgE levels was determined by ELISA. Unassigned: The eight major allergens were successfully expressed in insect cells and purified. All allergens induced a significantly higher sLT release from PBL of IBH-affected horses compared to healthy controls. There was a high correlation and substantial to excellent agreement between sLT release and serum IgE levels for six allergens, while for two, the agreement was moderate. Positivity rates in IBH horses were usually higher in IgE serology, but more false-positive results were obtained. The allergens performing best in both assays were Cul o 3, Cul o 8, and Cul o 9, with very high specificity and good sensitivity. Unassigned: Insect-cell-expressed recombinant allergens are functionally relevant and will open new opportunities for the study of hypersensitivity not only in horses but also potentially in human patients or other species. They will also greatly improve IBH diagnostics using cellular assays and IgE serology.
Publication Date: 2025-06-06 PubMed ID: 40547015PubMed Central: PMC12178880DOI: 10.3389/fimmu.2025.1597233Google Scholar: Lookup
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  • Journal Article

Summary

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This research investigates the allergenicity of certain proteins found in the saliva of biting insects, known as Culicoides, and their effect on horses experiencing insect bite hypersensitivity (IBH). The study successfully produced functional Culicoides allergens and proved that they trigger a higher release of sulphidoleukotrienes (immune system response agents) from horse leukocytes compared to healthy individuals. The study also found that functional allergens align positively with their respective IgE levels, revealing their potential role in improving diagnostic tools for IBH.

Research Methodology

  • This study aimed to create functional Culicoides allergens within insect cells and then assess their allergenicity through measuring sulphidoleukotriene release.
  • The release of sulphidoleukotrienes, or sLT, was studied due to their role in the immune system response against allergens.
  • Eight major Culicoides allergens were expressed in insect cells and then purified for use in the study.
  • The study consisted of two cohorts: 28 horses affected with IBH, and 24 healthy horses used as control subjects.
  • Each horse’s peripheral blood leukocytes were exposed to the eight produced allergens and the subsequent sLT release was measured.
  • Levels of allergen-specific serum IgE in each cohort were determined through ELISA, an antibody test.

Results and Findings

  • The study successfully expressed the eight major allergens in insect cells and purified them.
  • All allergens incited a significantly higher sLT release from peripheral blood leukocytes of horses suffering IBH when compared to healthy horses.
  • The research found a strong correlation and generally good agreement between the release of sLT and serum IgE levels for six of the allergens. For the remaining two, the agreement was moderate.
  • The results suggested higher IgE positivity rates in IBH-affected horses, however multiple false-positive results were obtained.
  • The allergens that performed the best in both assays were Cul o 3, Cul o 8, and Cul o 9, characterized by specificity and good sensitivity.

Conclusion and Implications

  • This study’s findings demonstrate that the studied allergens, when expressed in insect cells, are functional and relevant in understanding reactions to Culicoides bites.
  • These allergens could broaden the research field of Culicoides hypersensitivity in not only horses but also potentially in humans or other species.
  • The research also holds beneficial implications for improving diagnostics of IBH, through utilizing cellular assays and IgE serology.

Cite This Article

APA
Jonsdottir S, Stefansdottir SB, Mirkovitch J, Ziegler A, Torsteinsdottir S, Marti E. (2025). Culicoides allergens expressed in insect cells induce sulphidoleukotriene release from peripheral blood leukocytes of horses affected with insect bite hypersensitivity. Front Immunol, 16, 1597233. https://doi.org/10.3389/fimmu.2025.1597233

Publication

ISSN: 1664-3224
NlmUniqueID: 101560960
Country: Switzerland
Language: English
Volume: 16
Pages: 1597233
PII: 1597233

Researcher Affiliations

Jonsdottir, Sigridur
  • Institute for Experimental Pathology, Biomedical Center, University of Iceland, Keldur, Reykjavik, Iceland.
Stefansdottir, Sara Björk
  • Institute for Experimental Pathology, Biomedical Center, University of Iceland, Keldur, Reykjavik, Iceland.
Mirkovitch, Jelena
  • Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Berne, Bern, Switzerland.
Ziegler, Anja
  • Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Berne, Bern, Switzerland.
Torsteinsdottir, Sigurbjörg
  • Institute for Experimental Pathology, Biomedical Center, University of Iceland, Keldur, Reykjavik, Iceland.
Marti, Eliane
  • Division of Neurological Sciences, Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Berne, Bern, Switzerland.

MeSH Terms

  • Animals
  • Horses
  • Ceratopogonidae / immunology
  • Insect Bites and Stings / immunology
  • Insect Bites and Stings / veterinary
  • Allergens / immunology
  • Allergens / genetics
  • Immunoglobulin E / blood
  • Immunoglobulin E / immunology
  • Horse Diseases / immunology
  • Hypersensitivity / immunology
  • Hypersensitivity / veterinary
  • Insect Proteins / immunology
  • Insect Proteins / genetics
  • Leukocytes / immunology
  • Leukocytes / metabolism
  • Female
  • Male

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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