A possible link between sinusitis and lower airway hypersensitivity: the role of Staphylococcal enterotoxin B

Abstract

Background and aims: The prevalence of asthma has been keeping arising with unknown etiology. The cumulative evidence indicates that chronic rhinosinusitis (CRS) closely relates to asthma, but the detailed mechanisms remain unclear. The present study aimed to take insight into the role of Staphylococcus enterotoxin B (SEB) in a possible association between CRS and asthma.

Methods: 38 patients with both CRS and asthma underwent functional endoscopic sinus surgery. Serum specific IgE and cytokines, clinical symptoms of CRS and asthma were evaluated before and after the surgery. Peripheral blood mononuclear cells (PBMCs) were separated from the patients and cultured. Th2 response of the cultured PBMCs in the presence or absence of specific antigens and SEB was evaluated.

Results: Besides the improvement of CRS symptoms, amelioration of asthma was also observed in the patients with both CRS and asthma after the sinus surgery. The preoperatively elevated Th2 cytokines, IL-4 and IL-5, normalized postoperatively. Th2 response was generated with separated PBMCs in the presence of specific antigens. SEB was required for maintaining Th2 response in these separated PBMCs.

Conclusion: The present results indicate that a possible link exists between CRS and lower airway hypersensitivity. Sinusitis derived SEB may play a role in sustaining Th2 responses in the low airway hypersensitivity related to sinusitis.

Figure 1

SEB was evaluated with ELISA in the sinus wash fluids. Bars represent levels of SEB as mean ± SD. *, p < 0.05, compared with healthy controls. #, p < 0.05, compared with the second time within the same group. 1^st: samples are collected before the functional endoscope sinus surgery (FESS). 2^nd: samples are collected 2 months after the FESS. Healthy: healthy controls. CRS: patients with chronic rhinosinusitis. Asthma: patients with asthma. CRS-asthma: patients with both CRS and asthma.

Figure 2

CRS and asthma clinical symptoms improved after the FESS. A, lung function after antigen challenge was assessed by recording FEV1 falling rate in the period of 0~8 h. B, overall clinical scores reported by patients. *, p < 0.05, compared with the 1^st scores within the same group.

Figure 3

Serum specific IgE and Th1/Th2 cytokine levels were evaluated with ELISA. The serum samples were collected before (1^st) and 2 months (2^nd) after the FESS. *, p < 0.05, compared with the healthy controls.

Figure 4

Antigen skin test was performed before (1^st) and 2 months after the FESS (2^nd). The skin wheal area was recorded by image processing technique to represent the antigen induced skin responses. *, p < 0.05, compared with the 1^st results (paired student t-test).

Figure 5

Th1/Th2 responses of the separated and cultured peripheral blood mononuclear cells (PBMCs) in response to specific antigen stimulation. IL-4 levels (A) represent Th2 response and IFN-γ levels (B) represent Th1 response. The IL-4 (C) and IFN-γ (D) positively stained cells were detected by immune staining and flow cytometry. Data are expressed as mean ± SD. *, p < 0.05, compared with no treatment cells.

Figure 6

Time course of Th1/Th2 responses of the cultured PBMCs in response to stimulations of specific antigens and SEB. SEB was added to the culture on day 9. Data are expressed as mean ± SD. *, p < 0.05, compared with healthy controls.