The impact of intranasal staphylococcal enterotoxin B treatment on the inflammatory and functional phenotype of allergic asthma

Allergic asthma is a particularly heterogeneous chronic inflammatory condition of the airways that affects an increasing number of patients. Correlations between colonization with Staphylococcus aureus (S. aureus) and the development of allergic asthma have been recognized but remain incompletely understood. Interestingly, a substantial number of patients with severe asthma not reacting to common allergens show IgE specific for S. aureus enterotoxins. Based on this and other findings, S. aureus enterotoxin B (SEB) has been proposed to display a central player in the interplay between S. aureus carriage and allergic asthma.

We are seeking further mechanistic insights into the effects of SEB on the development and the phenotype of allergic asthma using a mouse model (C57Bl/6) for allergic asthma which is based on a local antigen challenge following peripheral sensitization with the model antigen ovalbumin (OVA). Here, we are analyzing the effects of intranasal treatment with SEB. We are assessing the recruitment of immune cells to the respiratory tract and the production of cytokines and OVA specific IgE.

Naïve mice, without additional treatment, react to intranasal treatment with SEB in a dose dependent manner. This reaction is mainly comprised of the recruitment of immune cells to the respiratory tract. Interestingly, the recruited cells include eosinophils, which are typically also increased in allergic airway inflammation. Following sensitization and challenge with OVA, mice show immune cell infiltration and Th-2 cytokine production in the respiratory tract as well as presence of specific IgE. The additional treatment with SEB during the challenge phase leads to distinct dose dependent changes in cell recruitment to the respiratory tract but does not exacerbate the asthmatic phenotype. Effects SEB-treatment on Th2 cytokine production in the respiratory tract as well as the production of specific IgE are currently analyzed.

The detailed analysis of the immunological effects of SEB at on allergic asthma in the mouse model will significantly increase our mechanistic understanding of the correlations between S. aureus carriage, SEB-specific Ig-responses and allergic asthma.