Airway inflammation induced after allergic poly‐sensitization can be prevented by mucosal but not by systemic administration of poly‐peptides

Abstract

Patients with multiple sensitizations require alternative forms of treatment, as the efficacy of conventional immunotherapy is unsatisfactory. In the present study, we sought to compare the efficacy of a subcutaneously (s.c.) and a mucosally applied polyvalent vaccine to reduce allergic immune responses within airway and lung tissues. Female BALB/c mice were intraperitoneally immunized with recombinant (r)Bet v 1, rPhl p 1 and rPhl p 5, followed by an aerosol challenge of birch and phleum pollen extract. For tolerance induction, either a mixture of the immunodominant peptides or a hybrid peptide of the respective antigens was s.c. injected or intranasally applied before poly-sensitization. Mucosal but not systemic pre-treatment with poly-peptides led to significant suppression of eosinophils and IL-5 production in bronchoalveolar lavages, as well as IL-5, IL-4, IL-13 and eotaxin levels in lung cell cultures. Lung histology showed a clear reduction of cellular infiltration and mucus production only in intranasally pre-treated mice. In accordance, also the systemic immune response, characterized by IgE-dependent basophil degranulation and IL-4 levels in vitro, was significantly reduced by mucosal antigen application, but only marginally influenced by subcutaneous pre-treatment. Both treatment routes led to up-regulated CTLA4 expression in splenocytes, whereas only after mucosal pre-treatment Foxp3 expression levels were enhanced in lung CD3(+) T cells. Furthermore, intranasal but not subcutaneous application of the peptides enhanced IL-10 levels in the lungs, indicating regulatory mechanisms operating in local tolerance induction. Mucosal application of peptides is superior to systemic application in preventing both local and systemic poly-allergic T helper2 immune responses, suggesting mucosal tolerance induction as an attractive strategy for the primary and secondary prevention of allergic multi-sensitization and lung pathology.