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Investigators also reported an increase in individualized FeNO associated with young female patients.
A new longitudinal study conducted primarily in Sweden investigated the changes in asthma biomarkers and immunoglobulin (IgE) over the course of life.
Investigators led by Nikolaos Tsolakis, Department of Women's and Children's Health, Uppsala University concluded that the young asthmatic patients in the study had IgE levels that declined over time, though the fraction of exhaled nitric oxide (FeNO) and blood eosinophil (B‐Eos) levels remained unchanged.
Additionally, accelerated lung function decline was reported in patients with detectable allergen‐specific IgE antibody levels (sIgE) at baseline, which correlated with type-2 biomarkers.
The team noted that similar studies had been conducted in the past that focused on lung function over time in both children and adults with asthma. Prior data suggested that total immunoglobulin E (tIgE) and atopy may have a central role in lung function and asthma, and early onset atopy at 1 month of age had been linked to reduced lung function at 18 years of age.
In the current study, investigators identified asthma biomarkers and phenotypes over time by following up with participants after a median of 43 months. In doing so, they hoped to examine associations with changes in clinical outcomes.
Tsolakis and colleagues initially recruited the Minimally Invasive Diagnostic procedures in allergy, Asthma, or food hypersensitivity Study (MIDAS) asthma cohort, which was comprised of 408 young participants with asthma and 118 random healthy control subjects.
All participants were aged 10-35 years old at baseline, and a total of 253 asthmatics were enrolled in the current study.
Investigators analyzed IgE antibodies from 2 different multiallergen tests, and B-Eos counts were analyzed using an automated cell counter.
Participants were then tasked with answering questions regarding their asthma symptoms over the 12 months via the Asthma-Related Quality of Life Questionnaire (mAQLQ), and their degree of asthma control was assessed using the Asthma Control Test (ACT). A score ≥20 reflected well‐controlled asthma.
Forced expiratory volume in 1 second (FEV1) was measured using a Masterscope spirometer (Viasys Healthcare GmbH), and FeNO measurements were performed using a chemiluminescence analyzer.
The investigators recorded a significant increase in both FeNO and FeNO% in the elevated sIgE group. A significant decline in lung function was seen in the groups with elevated and detectable sIgE levels (≥0.10 kUA/L) but not in the group with undetectable sIgE (<0.10 kUA/L).
Furthermore, the level of tIgE declined in the elevated sIgE group, but not the other 2 groups.
Investigators also reported that ACT scores improved significantly in the elevated sIgE group, and mAQLQ scores improved in all groups except in the undetectable sIgE group.
A sex-specific analysis was conducted during the study, where a significant decline in IgE antibodies to fx5 was observed in both groups. However, IgE to Phadiatop and total IgE were significantly decreased only in the female group.
Overall, a reduction in IgE levels were observed in young asthmatics throughout the study, with B-Eos and FeNO remaining unchanged during observation.
“Our findings suggest that exhaled NO signals for inflammatory mechanisms closely related to accelerated lung function decline independent of IgE levels and B‐Eos count,” the team wrote.
The study, “Relationship between longitudinal changes in type‐2 inflammation, immunoglobulin E sensitization, and clinical outcomes in young asthmatics,” was published online in Clinical and Translational Allergy.