Associations between sensitization to Staphylococcus aureus enterotoxins and Th2/eosinophilic inflammation and uncontrolled asthma

Background : Sensitization to Staphylococcus aureus enterotoxin (SE) is a known risk factor for asthma susceptibility and severity. However, detailed roles of SE sensitization in asthma, particularly in non-atopic asthma, remain unclear. Aims : To clarify clinical implications of SE sensitization in patients with asthma. Methods : In 224 patients with asthma (average age 62.3 years, 171 females) receiving inhaled corticosteroids, specific IgE against SEA or B (SEA/B-IgE) and common aeroallergens were determined. Non-atopic asthma was defined as the absence (<0.35 UA/mL) of specific IgE against 7 aeroallergens. Relationships between SEA/B sensitization (SEA/B-IgE ≥0.1 UA/mL) and clinical indices were analyzed. Results : A total of 84 (54%) of atopic patients and 21 (31%) of non-atopic patients were sensitized to SEA/B. Patients who were sensitized to SEA/B showed higher levels of serum total IgE, eosinophil cationic protein and periostin, more frequent sensitization to aeroallergens, and worse asthma control than those without sensitization to SEA/B. Sensitization to SEA/B was marginally associated with the most intensive treatment. In non-atopic patients (n=67), those who were sensitized to SEA/B were significantly older and showed higher levels of serum total IgE and periostin, and a greater annual decline in lung function than non-atopic patients without SEA/B sensitization. Conclusions : Sensitization to SEA/B contributes to persistent Th2/eosinophilic inflammation and poor disease control in patients with asthma. This sensitization may partly explain Th2 inflammation and greater lung function decline in “intrinsic” asthma.