Evaluating staphylococcal enterotoxins may help to better phenotype patients with asthma
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Key takeaways:
- Among patients with asthma, there was a significant association between female gender and sensitization to staphylococcal enterotoxin (SEB) IgE.
- There was no significant association between SEB-IgE sensitization and atopy, occurrence of exacerbations or corticosteroid dosages.
- Patients who were sensitized to SEB-IgE were younger and had earlier disease onset on average, making sensitization a possible independent risk factor for developing asthma.
Screenings that examine whether patients with asthma are sensitized to staphylococcal enterotoxins could help predict the evolution of comorbidities and lead to targeted therapeutic choices, according to a study published in Allergy.
Thus, improved phenotyping like this could increase the use of precision medicine, Cristiano Caruso, MD, director of the department of medical and surgical sciences at IRCCS Fondazione Policlinico Universitario Agostino Gemelli, Università Cattolica Sacro Cuore, Rome, and colleagues wrote.
The study included 249 adults with asthma, with 25.3% (95% CI, 19.9%-30.6%) testing positive for sensitization to staphylococcal enterotoxin B (SEB).
Sensitization to SEB-IgE had a significant association with gender (female vs. male, OR = 0.35; 95% CI, 0.2-0.62) and positive associations with chronic rhinosinusitis (CRS; OR = 2.65; 95% CI, 1.22-5.71) and CRS with nasal polyps (OR = 1.98; 95% CI, 1.08-3.52).
There were no significant associations between SEB-IgE sensitization and atopy, occurrence of exacerbations or high dosages of corticosteroids, defined as more than 7.5 mg per day of prednisone.
Researchers found that patients positive for SEB-IgE had weak and negative correlations between FEV1% and blood eosinophil count (P = 2.60e-02), as well as a strengthening positive correlation between blood eosinophil count and asthma severity based on Global Initiative for Asthma step, both of which were not apparent when evaluating the full population and the group of patients who were negative for SEB-IgE.
The researchers further found significant differences in age (P = .019), age of disease onset (P = .021) and IgE levels (P = .00074) between the groups of patients who were positive or negative for SEB-IgE.
Patients with severe asthma tended to be older (P = 7.7e-6), have the disease longer (P = .016) and have higher blood eosinophile count (P = 4.4e-6) than patients with milder asthma, but there was no relevant association between SEB-IgE sensitization and severe asthma.
There were no statistically significant differences in the proportions of severe and other degrees of asthma among the patients who were positive for SEB-IgE, but there were relevant differences in the distribution of the number of exacerbations in the previous year.
Noting that patients who were sensitized to SEB-IgE were younger and had earlier disease onset on average, the researchers suggested that SEB-IgE sensitization could be an independent risk factor for developing asthma.
With a lack of correlation between blood eosinophil counts and disease severity among patients with SEB-IgE sensitization, SEB-IgE could be an independent factor in the clinical outcome of asthmatic patients as well, the researchers continued.
By including SEBs in the initial screenings of patients with severe asthma, the researchers concluded, clinicians may be able to better phenotype patients, predict the evolution of comorbidities, and make better therapeutic choices.
Perspective
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Andrew M. Namen, MD, FCCP, FAASM
This is a well-structured retrospective analysis of a clearly defined population. The hope of such a study design is the identification of a signal staphylococcal endotoxin IgE expression that may identify specific treatment pathways for patients with severe asthma.
Additionally, though they may appear to be appropriate candidates, patients with severe asthma may not respond to biologic therapy as hoped. These patients fail or have a marginal response to the prescribed biologic.
So, are there markers that can help drive providers to a different choice of treatment that will provide a more consistent and greater response to treatment for patients who suffer from severe asthma? That’s a goal of precision medicine.
The association between staphylococcal endotoxin and asthma severity has been noted. Unique in this study is how it found that SEB IgE expression correlates with nasal polyposis and asthma severity among a well-defined cohort of patients with severe asthma.
The researchers observed that patients with SEB expression appear different from other phenotypes of asthmatics, suggesting alternative biologic treatment. Testing patients for SEB IgE may be helpful and direct patients to an alternative treatment strategy and possibly an improved response.
This analysis sets the stage for a prospective randomized control trial among patients with severe asthma expressing SEB IgE who fail to respond to non-IgE biologics, or those who early on have SEB IgE, and compare response to treatment with IgE biologics with other treatments. Regardless, we are entering a more precise approach to treatment based on patient innate biologic expression.
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