Phenotyping patients with Severe asthma: An enterotoxin-based approach

<bold>Background:</bold> Sensitization to Staphylococcus aureus enterotoxins (SEs) is associated with an increased risk for severe asthma development. Limited data exists regarding the association of seropositivity for SEs and the different aspects of severe asthma. <bold>Objective:</bold> We aimed to determine whether the presence of SEs is associated with parameters expressing inflammatory cells in the airways, features of airway remodeling and different aspects relating to asthma assessment and severity. <bold>Methods:</bold> 50 patients with severe asthma were recruited in the study. Demographics, comorbidities, asthma duration, and asthma medication were recorded by treating physicians. SEs measurement, lung function, atopic status, ACT, sputum induction, bronchoscopy with BAL and indices of airway remodeling were also assessed. <bold>Results:</bold> 12 patients were positive to enterotoxins sensitization. Patients seropositive to SEs significantly differed in regard to FEV1% pred compared to seronegative ones. Analyzing the inflammatory variables obtained from induced sputum, BAL and endobronchial biopsies the only significant difference was that of Smooth Μuscle Αrea (SMA)% which was greater to seropositive to SEs patients. The multivariate linear regression analysis showed two significant associations of SEs seropositivity. A negative with FEV1 % pred with beta standardized coefficient 95%CI -0.054 (−0.083, -0.031), p<0.001, and a positive with SMA% with beta standardized coefficient 95%CI 0.054 (0.081,0.037), p<0.001. <bold>Conclusion:</bold> Seropositivity to SEs in severe asthma is associated with more severe airflow limitation, οbstruction and upregulation in SMA, indicating an important role in remodeling process.