House dust mite allergy affects over half of asthma patients. The major allergen, Der p 2, is recognised by nearly 90% of allergic patients. Continuous exposure to this allergen leads to a type of asthma characterised by bronchial constriction and inflammation of the airways, which in the most severe cases can lead to considerable disability and sometimes serious attacks and death.
“Desensitisation” is the only current treatment for respiratory allergies. It involves exposing patients to the allergen, usually by the sublingual route, so that their immune system gradually generates protective cells and antibodies. Thanks to technological advances and genetic engineering, so-called hypoallergenic peptides, derived from allergens and used as a vaccine, represent a new direction for immunotherapy, especially for house dust mite asthma. This strategy has the three-fold advantage of being effective in a short time, offering prolonged protection, and reducing the allergic side-effects of desensitisation.
To accomplish this, mice were vaccinated with this peptide on 2 occasions: before and during allergic sensitisation to house dust mites. The researchers then measured bronchial obstruction in these mice in response to metacholin (a drug that induces bronchoconstriction), and demonstrated that vaccination with this peptide resulted in normal bronchial reactivity in asthmatic mice.
Furthermore, vaccination with this peptide induces anti-inflammatory activity, by reducing the chemical messengers that attract eosinophils and neutrophils to the bronchi and lungs, while reducing the T-lymphocyte activation and immunoglobulin E secretion responsible for the allergic reaction.
For the researchers, the protective role of vaccination, using a hypoallergenic peptide, is a very attractive therapeutic option for stemming the progression of asthma, especially in children at risk. Additional studies in animals are necessary before the first therapeutic trials in humans can be planned.
The peptide used is the subject of a patent filed by Inserm Transfert.
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Prevention of allergic asthma through Der p 2 peptide vaccination. Bouchaud G, Braza F, Chesné J, Lair D, Chen KW, Rolland-Debord C, Hassoun D, Roussey-Bihouée T, Cheminant MA, Brouard S, Bodinier M, Vrtala S, Magnan A. J Allergy Clin Immunol. 2015 Feb 11