eMedicineLive

Asthma is a fairly common disease with about 300 million people suffering from it worldwide. And with the increasing levels of pollution, the incidence of asthma is also increasing. Allergens in the environment, such as pollen and dust mites, are the most common cause behind the condition. Exposure to them stimulates the airway muscles to constrict within minutes resulting in mild to severe shortness of breath. This early response to allergens is triggered by the stimulation of mast cells which, in turn, release chemical signals that result in airway constriction. However, certain asthmatics exhibit a late response three to four hours after the exposure to allergens. The reason behind this late response remained largely unexplained.

 

A new research, published in the journal “Thorax”, has found the reason behind the late phase of symptoms that occurs several hours after exposure to allergens. The research, led by scientists from Imperial College London, and conducted on mice and rats, concluded that it could be because of the stimulation of sensory nerves in the airways. Stimulation of these nerves reflexly stimulates other nerves and results in secretion of acetylcholine, a neurotransmitter which causes the airways to constrict.

 

Until now, steroids have been the mainstay of treatment for asthma. But it was found lacking in providing adequate relief from the late phase of symptoms. If the findings of the new research are found applicable in humans as well, this would effectively mean that using anticholenergic drugs, which act against acetylcholine, may prove beneficial in treating asthma patients that experience late phase responses following exposure to allergens. A recent study conducted on 210 asthma patients found that anticholenergic drug tiotropium when added to a steroid inhaler, helped in providing relief from the symptoms of the late phase of asthma. However, the reason behind it could not be explained then. Now, in the light of the latest study by the Imperial team, one can say that tiotropium blocked the release of acetylcholine and therefore, alleviated the symptoms.

 

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