Thanks to a micro-device that mimics the behavior of the human airways, researchers have succeeded in understanding the functioning of bronchospasm, which mainly affects asthmatics.
Bronchospasm is a sudden, involuntary contraction of the smooth muscles of the distal bronchi. If it occurs mainly in people with respiratory diseases such as asthma or chronic obstructive pulmonary disease (COPD), it can also strike people with no particular health concerns, including smokers. This very complex phenomenon is difficult for researchers to study, as the human respiratory system cannot be modeled in animal studies. However, by developing a micro-device that imitates the behavior of the human respiratory tract, researchers have just managed to understand how bronchospasm works. The results of their study appeared in the July edition of the journal Nature Biomedical Engineering.
To analyze the biochemical and mechanical signals occurring between cells during spasm, researchers at Rutgers and other institutions created a micro-device the size of a thousandth of a human hair. This contains cells from healthy and asthmatic lungs capable of mimicking the function of a lung at a cellular level.
By triggering a bronchospasm on the device, they discovered that the initial contraction leads to the secretion of hormone-like compounds that can induce further constriction or conversely relax the spasm. In asthmatics, the smooth muscle surrounding the airways is more reactive and contracts more easily to respond to stimuli like allergens. This leads to prolonged bronchial spasms, gasping and shortness of breath.
“An important screening tool for the development of new drugs”
Inducing a second asthmatic trigger during bronchial spasm at a specific time causes smooth muscle to relax and the spasm to stop, they also found.
Treatments for curing bronchospasm haven’t changed in the past fifty years, researchers say. And while they work for most people, they’re not 100% effective, notes Reynold Panettieri, director of the Rutgers Institute for Translational Medicine and Science.
“The micro-device allowed us to dig deeper into how individual cells interact with each other in relation to smooth muscle contraction in a variety of lung diseases,” he explains. And to conclude: “Being able to study mechanics at the single-cell level and see thousands of cells simultaneously can be an important screening tool for the development of new drugs for people with asthma who do not respond to current treatment”.
15% of asthmatics do not feel their bronchospasms
Today, bronchospasm is treated with bronchodilators. These inhaled medications attach to the muscles around the lungs to relax them. This decreases the pressure exerted, which makes it possible to avoid violent bronchospasms and to reduce the appearance of mucus in the bronchi. In cases where the patient too regularly suffers from bronchospasms, doctors sometimes operate on him. We then speak of tracheotomy: the forced and surgical opening of a bronchus.
Most often, the affected people suffer from asthma. It is estimated that 15% of asthmatics hardly notice their bronchospasms, as they are used to having their airflow obstructed. However, it is possible that regular smokers, people too exposed to pollution, dust or a humid climate, are affected by this severe respiratory failure.
If the patient is very weak at the time of the contractions, the latter can have serious consequences. Among them, fainting or coma, panic attack, tremors, or even hypoxia (insufficient oxygen supply). Worse still, if the bronchospasm occurs during anesthesia, the effect of the drugs may lead to respiratory arrest.
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