Chronic sinusitis with nasal polyps: staphylococcal exotoxin immunoglobulin E and cellular inflammation

Abstract

Background: The etiology of chronic sinusitis with nasal polyposis (CS/NP) remains enigmatic. Frequently, Staphylococcus aureus is present in the nose of CS/NP patients, although the significance is unclear. Recent reports have suggested the hypothesis that these bacteria may secrete exotoxins triggering the inflammatory mucosal changes seen in CS/NP. This mechanism of immunopathology has been established in other diseases associated with Staphylococcus colonization and exotoxin secretion such as atopic dermatitis. In atopic dermatitis, the exotoxins incite a local superantigen response in which clonal T-cell activation and massive cytokine release occur in the affected skin. Second, these exotoxins can act as traditional allergens, stimulating a typical immunoglobulin E (IgE) response in the serum, which has been correlated with disease severity. This study is designed to begin the assessment of the hypothesis that a similar mechanism takes place in CS/NP.

Methods: Serum was drawn from patients with CS/NP undergoing endoscopic sinus surgery as well as 13 atopic and nonatopic control subjects without sinusitis. IgE levels to S. aureus exotoxins A (SEA), SE exotoxins B (SEB), and toxic shock syndrome toxin 1 were measured using enzyme-linked immunosorbent assay. Tissue eosinophilia and the presence of lymphocytes on hemotoxylin and eosin-stained sections of polyps were scored by a blinded pathologist and correlated to presence of toxin IgE in the serum.

Results: Staphylococcal exotoxin (SE)-specific IgE was found in the serum of 5/10 (50%) of the patients with CS/NP. In contrast, 0/13 control patients had IgE to the exotoxins (p = 0.031). Polyp eosinophil, lymphocyte, and mononuclear cell counts were compared in IgE exotoxin-positive and -negative subjects. A trend toward increased eosinophil counts in patients with SE IgE (SE IgE+) was present, but not statistically significant.

Conclusion: These results indicate that a high percentage of CS/NP patients show a systemic IgE response to S. aureus exotoxins in comparison with controls without CS/NP. Although these results are consistent with the actions of Staphylococcus toxins in other diseases, additional work is necessary to establish a local superantigen response in the nasal mucosa of CS/NP patients.