Scientists may have hit upon an effective way to block asthma
attacks by identifying the two most significant biological
triggers that bring them on.
Researchers from the Universities of California-San Francisco (UCSF),
Johns Hopkins and Duke universities demonstrate that these two
triggers for asthma are tied to a specific calcium-activated
chloride channel, called TMEM16A.
They regulate airway secretions and smooth muscle contraction, the
two major factors linked with asthma attacks, according to the
journal "Proceedings of the National Academy of Sciences".
"Maybe if we could inhibit both of these processes by blocking
this one channel, we could affect the two symptoms of asthma,"
said senior study author Jason Rock, assistant professor of
anatomy at UCSF.
Asthma, a respiratory disorder that causes shortness of breath,
coughing and chest discomfort, results from changes in the airways
that lead to the lungs.
It affects 18.7 million adults and 7.0 million children in the US
alone, according to the Centres for Disease Control and
Normally, humans have few mucus-producing cells. Those suffering
from asthma, however, have an elevated number of these cells
lining the tubes that lead to the lungs.
"The overabundance of mucus plugging the airways combined with
hyper-contractility of the smooth muscle - when the tubes get
really small - make it difficult to move air in or out," Rock
said. "A lot of people equate that feeling with breathing through
Rock and colleagues focused on a calcium-activated chloride
channel called TMEM16A. This channel secretes chloride ions,
besides regulating biological processes such as neuron firing,
gastrointestinal activity and the secretion of sweat and tears.
The authors identified three chemicals that inhibit the channel.
"We tested the ability of these chemicals to inhibit TMEM16A and
other channels, and we found that they specifically block
TMEM16A," Rock said.
"It is great that we came across these molecules that were unknown
previously since we can now try to get into clinical trials to
benefit patients," said Rock.