Epicutaneous immunotherapy using a new epicutaneous delivery system in mice sensitized to peanuts.

BACKGROUND: Peanut allergy is a life-threatening condition for which new efficient and safe treatment is expected. We evaluated epicutaneous immunotherapy (EPIT) as a new alternative treatment for peanut allergy in sensitized mice. METHODS: Sixty BALB/c mice were sensitized by gavages with peanut protein extract (PPE) mixed with cholera toxin. An epicutaneous delivery system, coated with 100 µg PPE (Viaskin®, DBV Technologies, Paris, France), was applied to intact skin every week during 48 h (EPIT; n = 20). This group was compared with sensitized mice treated with subcutaneous immunotherapy (SCIT; n = 20), untreated sensitized mice (sham, n = 20), and naive mice (naive; n = 20). After the 8-week treatment, a histamine release test, airway hyperreactivity measurement by plethysmography, and a resistance-compliance measurement after the challenge were performed. Blood and bronchoalveolar lavage were sampled for serology, cytokines, and cytology. RESULTS: Specific IgE (sIgE) increased after sensitization in the EPIT (0.26 µg/ml) and SCIT (0.21 µg/ml) groups and decreased after treatment (0.09 µg/ml, p < 0.001 and 0.06 µg/ml, p < 0.001, respectively). The IgG1/IgG2a ratio decreased in the EPIT and SCIT groups versus the sham group (3.7; p < 0.001 and 2.7; p < 0.01 and 15.1, respectively). At the higher metacholine concentration, enhanced pause values were lower in the EPIT and SCIT groups than in the sham group (7.29, 6.74, and 10.99, p < 0.01, respectively), and did not differ from that of the naive group (5.06). Resistance-compliance was reversed in the treated groups versus the sham group (p < 0.001). IL-4, IL-5, IL-13, eotaxin, and eosinophils were reduced in the BAL of the EPIT and SCIT groups versus the sham group (p < 0.001). CONCLUSION: In peanut-sensitized mice, based on biological and physiological responses, EPIT is as efficient as subcutaneous treatment which is the reference method in immunotherapy.

Sensitization to inhaled ryegrass pollen by collateral priming in a murine model of allergic respiratory disease.

BACKGROUND: Mouse models of asthma suffer from the necessity to prime the animals by injections before respiratory exposure. Our aim was to develop a mouse model that mimics the progression of human allergic disease upon low-dose inhaled allergen exposure. METHODS: Mice were primed intraperitoneally to ovalbumin (OVA) before they were exposed repeatedly to aerosols of either OVA, ryegrass (Lolium perenne) pollen extract, or both concomitantly. The sensitization to ryegrass pollen proteins was evaluated by measurement of specific serum antibody, by the respiratory response to a challenge with ryegrass pollen extract and by lung cytokine production after challenge. RESULTS: Inhalation of ryegrass pollen extract alone did not result in sensitization. Sensitization to inhaled ryegrass pollen proteins, however, did occur in mice that had been sensitized to OVA by intraperitoneal injections and were then exposed to inhaled ryegrass pollen extract and OVA simultaneously. T and B cell priming was ascertained by ryegrass pollen-specific IgG1 and IgE antibody production and by induction of airway inflammation and of Th2 cytokine mRNA transcripts in the lungs upon airway challenge with ryegrass pollen extract. A progressive spread of the IgE/IgG1 response to different ryegrass pollen proteins could be visualized in immunoblots by comparing antibody patterns at day 56 and 86. CONCLUSIONS: Low-dose inhalatory allergen exposure results in sensitization when airways are exposed at the same time to another allergen to which the animals are already sensitized. This model can help to unravel the mechanisms that underlie the development and progression of respiratory allergic diseases.

Nicotine activates the chemosensory cation channel TRPA1.

Topical application of nicotine, as used in nicotine replacement therapies, causes irritation of the mucosa and skin. This reaction has been attributed to activation of nicotinic acetylcholine receptors (nAChRs) in chemosensory neurons. In contrast with this view, we found that the chemosensory cation channel transient receptor potential A1 (TRPA1) is crucially involved in nicotine-induced irritation. We found that micromolar concentrations of nicotine activated heterologously expressed mouse and human TRPA1. Nicotine acted in a membrane-delimited manner, stabilizing the open state(s) and destabilizing the closed state(s) of the channel. In the presence of the general nAChR blocker hexamethonium, nociceptive neurons showed nicotine-induced responses that were strongly reduced in TRPA1-deficient mice. Finally, TRPA1 mediated the mouse airway constriction reflex to nasal instillation of nicotine. The identification of TRPA1 as a nicotine target suggests that existing models of nicotine-induced irritation should be revised and may facilitate the development of smoking cessation therapies with less adverse effects.