Asthmatics only sensitized to Staphylococcus aureus enterotoxins have more exacerbations, airflow limitation, and higher levels of sputum IL-5 and IgE.

Abstract

Staphylococcus aureus Enterotoxins (SE) may act as superantigens and induce an intense T cell activation causing local production of polyclonal IgE and resultant eosinophil activation. To assess whether asthma with sensitization to SE but not to common aero-allergens (AA) displays different inflammatory characteristics. We conducted a prospective study on a series of 110 consecutive patients with asthma recruited from the University Asthma Clinic of Liege. We compared clinical, functional and inflammatory characteristics of this general population of asthmatics categorized in 4 groups according to sensitization to AA and/or SE. We also compared sputum supernatant cytokines in patients sensitized to SE or not. Asthmatics only sensitized to AA represented 30%, while 29% were sensitized to both AA and SE. One fifth of the population had no specific IgE. Sensitization to SE but not to AA (21%) was associated with later onset of disease, higher rate of exacerbations, nasal polyps and more severe airway obstruction. As for airway type-2 biomarkers, patients presenting with specific IgE against SE (SE-IgE) displayed higher FeNO, sputum IgE and sputum IL-5 levels but not IL-4. We confirm that the presence of SE-IgE is associated with elevated serum IgE to levels well above those observed in patients only sensitized to AA. Our study suggests that asthma specialists should measure SE-IgE during the phenotyping process as it may allow the identification of a subgroup of patients with more asthma exacerbations, more nasal polyposis and chronic sinusitis, lower lung function and more intense type-2 inflammation.