Synergism of Staphylococcus aureus Colonization and Allergic Reaction in the Nasal Cavity in Mice

Background: The aim of this study is to investigate the reciprocal effect of Staphylococcus aureus colonization and allergic rhinitis in an allergy model of mice. Methods: BALB/c mice with intraperitoneal ovalbumin (OVA) sensitization and/or intranasal S. aureus inoculation were prepared. The following 4 groups were designed: an OVA-sensitized S. aureus-inoculated (AR-SA) group, an OVA-sensitized uninoculated (AR) group, a nonsensitized S. aureus-inoculated (SA) group, and a nonsensitized uninoculated (control) group. After intranasal OVA challenge, nasal lavage fluid, peripheral blood, and nasal mucosa were collected. Polymorphonuclear cells in the nasal lavage fluid were counted, serum OVA-specific IgE and IgG1 were measured by enzyme immunoassays, and IL-4, IL-5, and IFN-γ mRNAs in the nasal mucosa were assessed by quantitative real-time reverse transcription-PCR. The number of S. aureus in the nasal mucosa and lavage fluid was counted. Results: Both eosinophil and neutrophil counts were larger in the AR-SA group than in the other groups. Both IgE and IgG1 levels were higher in the AR and AR-SA groups than in the SA and control groups, and the IgG1 level was higher in the AR-SA group than in the AR group. The expression of IL-4 mRNA was higher in the AR-SA group than in the other groups, and the expression of IL-5 mRNA was higher in the AR-SA group than in the SA group. The AR-SA group showed higher counts of S. aureus in the nasal mucosa than the SA group. Conclusion: These results indicate the mutually potentiating effect of S. aureus colonization and allergic rhinitis.