Doctors have known for years that common colds can trigger asthma attacks, but they didn't understood why. A new study may have unlocked that mystery and given health care providers the tools they need to treat these cold-triggered asthma attacks.

A team of researchers from the National Heart and Lung Institute at Imperial College London have identified a molecule that may trigger an asthma attack during a cold. The researchers found that asthmatics have cells lining their airways that are more prone to producing a small molecule called IL-25, and it is this molecule that sets off a sequence of events that culminate in an asthma attack.

For the study, which was published in the journal Science Translational Medicine, researchers compared lung cells from people with and without asthma and found that when the lung cells of patients with asthma were infected with a rhinovirus — a main cause for the common cold — they produced 10 times as much IL-25 than the lung cells from their non-asthmatic peers. Researchers performed a similar study in which they infected volunteers with a cold and then looked directly at the lung tissue in the patients. Again, they found that asthmatics had more IL-25 in their lung cells than participants without asthma. 

The good news is that the team found a way to block the production of IL-25, at least in mice. If they can perfect a method for performing this function in humans, it may give doctors a new way to help their asthmatic patients through cold and flu season.

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