Published Online: January 11, 2016
Recent research has demonstrated that asthma is made up of multiple distinct subtypes with different clinical trajectories and responses to medical therapy. However, the molecular mechanisms underlying the expression of different asthma subtypes remain unclear.
In a research article recently published in The Journal of Allergy & Clinical Immunology (JACI), Howrylak and colleagues evaluated gene expression levels among patients with different asthma subtypes. They used blood samples collected from 299 young adult participants, 9-14 years following their participation in the Childhood Asthma Management (CAMP) study. The original CAMP study investigated the effects of inhaled anti-inflammatory medications on asthma symptoms.
The authors found that even as asthmatic children aged and their asthma symptoms improved, differences in levels of gene expression persisted among subjects with different asthma subtypes. In particular, subjects who had an atopic subtype, associated with a higher prevalence of allergic symptoms and reactive airways, had notable differences in the levels of expression of multiple genes, including histone deacetylase 2 (HDAC2), a gene previously implicated in the development of steroid-resistant asthma. In addition, there were differences in expression levels of several novel genes, not previously linked to asthma, such as spermidine synthase (SRM), solute carrier family 33, member 1 (SLC33A1), purinergic receptor P2Y, G-protein coupled, 10 (P2RY10), and adducing 3 (gamma) (ADD3).
The authors’ findings link differences in gene expression to clinical differences in asthma subtypes, suggesting important differences in the development of asthma among different patients. Moreover, these gene expression differences were apparent many years following the diagnosis of asthma, often after clinical symptoms of asthma had improved, suggesting that even though asthma symptoms may improve with time, the underlying molecular differences persist.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.