About 235 million people all over the world suffer from asthma. Different people have different triggers, but up to 90 percent of cases are caused by viruses, the most common of which are rhinoviruses, the primary culprit behind the common cold.
According to a study published in the Science Translational Medicine journal, British researchers may have found the reason why the common cold commonly leads to asthma attacks, a molecule known as IL-25.
Lung cells from people with and without asthma were compared after being infected with a rhinovirus. After the infection, lung cells from asthmatic individuals had 10 times more of the molecule IL-25 than those from people without asthma.
In another experiment, airways were compared. Infected volunteers with asthma also had higher levels of IL-25 in their airways compared with those who do not have asthma.
"Our research has shown for the first time that the cells that line the airways of asthmatics are more prone to producing a small molecule called IL-25, which then appears to trigger a chain of events that causes attacks," said co-lead author Nathan Bartlett from Imperial College London's National Heart and Lung Institute.
The molecule IL-25 is of interest to researchers studying asthma because of its role in the onset of type-2 immune responses. Rhinovirus infections are typically mild but they end up worsening in asthmatic individuals because IL-25 promotes the production of other type-2 cytokines, which then triggers type-2 immune responses.
After identifying IL-25 as the one responsible for instigating more severe reactions in the body, researchers hope to move on to working toward blocking the molecule, consequently stopping associated immune responses as well in the process. They have already managed to isolate an antibody that can block IL-25 in mice so researchers are gearing up for human testing next.
"This new study provides exciting results about potential ways to address this big unmet medical need. The next steps are to test blocking IL-25 in humans, and to investigate other possible pathways that could be important in asthma attacks and pool this knowledge to develop effective treatments," explained co-lead author Dr. Sebastian Johnston, also from the National Heart and Lung Institute.
Existing medications that use steroids have been effective at managing the usual asthma symptoms, but there exists still that the possibility that an attack can worsen, prompting hospitalization for an asthmatic individual.
Further progress of this study means finding a better way to control symptoms, potentially stopping them as soon as they manifest to take away risks of worsening.
