Although many specific immunotherapies have been tried against asthma, they have not been very successful as they are not very efficient and can cause serious side effects. However, a new vaccine, which is a DNA-based vaccine against Dermatophagoides farinae 1 (Derf1) allergen, has shown promising results and is devoid of deleterious effects. This particular allergen is the commonest allergen responsible for the flaring up of asthma in Europe. The vaccine has been developed by the scientists at Inserm and CNRS, University of Nantes, and a review has been published in the latest issue of the journal Human Gene Therapy.
Allergic asthma affects about 300 million people worldwide and is usually caused by an allergic reaction to some environmental allergen. Many of these patients are allergic to dust mite. Derf1 is the commonest allergen carried by the dust mites and almost half of them produce specific IgE antibodies against it.
At present, apart from administration of medicines like corticosteroids which provide relief from the symptoms, the patients are desensitized by giving them repeated, increased dose of the allergens. This reduces the hypersensitivity of the airways and produces a less violent reaction on subsequent exposure to the allergen. However, not all patients react very favorably to this process.
The developers of the new vaccine first used it against healthy mice. The vaccine also contained a block copolymer 704. It produced a strong humoral and cellular response. They then tried the vaccine against asthmatic mice. It resulted in the production of specific antibodies against Derf1 allergen. When two injections were administered intramuscularly at an interval of three weeks, there was a considerable reduction in the hypersensitivity of the airways. The levels of inflammatory cytokines present normally in the lungs of mice suffering from asthma were also greatly reduced. Encouraged by the positive results in experiments on mice, the researchers are working on the regulatory pre-clinical development of the vaccine so that clinical trials in humans may be undertaken at the earliest.