Janine Beale and colleagues from the Imperial College and the King’s College London, UK, found that interleukin (IL)-25 is perhaps the key trigger of asthma attacks, induced by viruses, as reported in the October issue of Science Translational Medicine.
Respiratory viruses (and mostly rhinoviruses that cause the common cold) are known to be the most common triggers of asthma exacerbations.
It is also known that T helper (Th)2 cell immune responses are involved in these exacerbations, but it is not known how rhinoviruses are linked to Th2 immunity, and asthma exacerbations respectively.
The UK’s research team demonstrates that rhinoviruses are able to induce IL-25 production in lung epithelial cells, and asthmatic airways have an increased propensity to produce this cytokine. The study also shows that nasal mucosa of asthmatic subjects has detectable increased IL-25 during experimental rhinovirus infection, and both baseline and infection IL-25 peak levels are significantly higher in asthma.
Of note, IL-25 (IL-17E) belongs to the IL-17 cytokine family, and is known to induce Th2 cell immune responses. This is related to the upregulation of Th2-related cytokines such as IL-4, IL-5, and IL-13 that play a central role in allergy and asthma development.
Dr. Nathan Bartlett, the joint lead author of the study said that “airways of asthmatics are more prone to producing IL-25…… By targeting this molecule we could potentially discover a much-needed new treatment to control this potentially life-threatening reaction in asthma sufferers.”
Source: Sci Transl Med, 2014 Oct 1;6(256):256ra134. doi: 10.1126/scitranslmed.3009124.