The odor receptors on the cells, might be a therapeutic target, Ben-Shahar suggests. By blocking them, it might be possible to prevent some attacks, allowing people to cut down on the use of steroids or bronchodilators.
Every breath you take
When a mammal inhales, volatile chemicals flow over two patches of specialized epithelial tissue high up in the nasal passages. These patches are rich in nerve cells with specialized odorant-binding molecules embedded in their membranes.
If a chemical docks on one of these receptors, the neuron fires, sending impulses along the olfactory nerve to the olfactory bulb in the brain, where the signal is integrated with those from hundreds of other similar cells to conjure the scent of old leather or dried lavender.
Aware that airway diseases are characterized by hypersensitivity to volatile stimuli, Ben-Shahar and his colleagues realized that the lungs, like the nose, must have some means of detecting inhaled chemicals.
Earlier a team at the University of Iowa, where Ben-Shahar was a postdoctoral research associate, had searched for genes expressed by patches of tissue from lung transplant donors. They found a group of ciliated cells that express bitter taste receptors. When offending substances were detected, the cilia beat more strongly to sweep them out of the airway. This result was featured on the cover of the August 28, 2009 issue of Science.
But since people are sensitive to many inhaled substances, not just bitter ones, Ben-Shahar decided to look again. This time he found that these tissues also express odor receptors, not on ciliated cells but instead on neuroendocrine cells, flask-shaped cells that dump serotonin and various neuropeptides when they are stimulated.
This made sense. "When people with airway disease have pathological responses to odors, they're usually pretty fast and violent," said Ben
|Contact: Diana Lutz|
Washington University in St. Louis