Published online: March 30, 2018
There is growing interest in the use of Type 2 biomarkers such as blood eosinophils, Fraction of Exhaled Nitric Oxide (FeNO), serum immunoglobulin E (IgE), and serum periostin to predict the risk of severe exacerbations of asthma, lung function decline, and responsiveness to asthma therapies in patients with asthma. A number of studies have shown an association between higher levels of Type 2 biomarkers and increased risk of asthma exacerbations. Generally, these have been undertaken in highly select groups of patients with severe eosinophilic asthma refractory to standard treatments, representing only a small proportion of patients with asthma.
In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice, Semprini and colleagues examined the association between blood eosinophils, FeNO, serum IgE, and serum periostin and the time to severe exacerbation of asthma in a broad range of asthma patients. The researchers recruited 212 asthma patients with mild to moderate asthma and obtained measurements of baseline blood eosinophils, FeNO, serum IgE, and serum periostin. The patients were followed for a mean of 2.8 years, to see if high levels of Type 2 biomarkers at baseline were predictive of severe asthma exacerbations in this milder asthma group. A total of 62 (32%) of participants had at least one severe exacerbation during the follow up period.
The researchers found that higher baseline FeNO and serum IgE levels were associated with a lower risk of severe asthma exacerbation in this group, while there was no association between baseline eosinophil counts or serum periostin levels and risk of severe exacerbation. This highlights the importance of considering non-eosinophilic or “Type 2 low” asthma as an important clinical entity in the broader asthma population. Type 2 low asthma is more likely to be resistant to treatments targeting the Type 2 inflammatory pathways such as inhaled corticosteroids and the newer monoclonal antibody therapies. Clinicians should be aware that the associations seen between Type 2 biomarkers and increased risk of severe exacerbations of asthma may not apply to a broad population of patients with mild to moderate asthma.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.