Presence of IL-5 protein and IgE antibodies to staphylococcal enterotoxins in nasal polyps is associated with comorbid asthma

Background

Nasal polyps often are associated with asthma. The phenotype of these patients is unknown.

Objective

To identify the mucosal factors associated with asthma comorbidity, we analyzed the inflammatory patterns of nasal polyps.

Methods

Nasal polyps from 70 Belgian patients, 34% with asthma, were analyzed for type of inflammation, T-cell cytokines, and IgE antibodies to Staphylococcus aureus enterotoxins. The same investigations were repeated in 93 Chinese patients with polyps, a group with a low asthma comorbidity rate (8%).

Results

In Belgian patients with polyps, 54% of samples showed eosinophilic inflammation. A classification tree evaluation identified IL-5 as the main positive determinant. Enterotoxin IgE in tissue (37%) was associated with significantly increased total IgE and eosinophil cationic protein concentrations. Expression of enterotoxin IgE, total IgE at greater than 1,442 kU/L, and eosinophil cationic protein at greater than 17,109 μg/L in samples with a total IgE concentration of greater than 246 kU/L significantly predicted asthma (odds ratio, 5.8-13). Only 7.5% of the samples from Chinese patients with polyps showed eosinophilic inflammation. IL-5 was confirmed as a positive determinant of eosinophilic inflammation, and enterotoxin IgE in tissue (17% of patients) was associated with significantly increased total IgE and eosinophil cationic protein concentrations. The expression of IL-5 or total IgE at greater than 790 kU/L in samples with an IL-5 concentration of greater than 194 pg/mL significantly predicted comorbid asthma (odds ratio, 17.2-96).

Conclusion

Mucosal inflammation in nasal polyps orchestrated by T_H2 cytokines and amplified by S aureus enterotoxins is characterized by an increased eosinophilic inflammation and formation of IgE antibodies. This phenotype is associated with comorbid asthma in white and Asian patients with nasal polyps.

Key words: Chronic rhinosinusitis, nasal polyps, asthma, T-cell cytokines, Staphylococcus aureus enterotoxins, IgE

Abbreviations used: ECP, Eosinophilic cationic protein, MPO, Myeloperoxidase, OR, Odds ratio, SE, Staphylococcus aureus enterotoxin