Not sure what’s causing your child’s asthma?
A new quick-and-easy nasal swab test for kids can diagnose the specific immune system drivers behind their asthma, potentially opening the door to better treatments, researchers say.
The test diagnoses a child’s asthma subtype, also called an endotype.
“Because asthma is a highly variable disease with different endotypes, which are driven by different immune cells and respond differently to treatments, the first step toward better therapies is accurate diagnosis of endotype,” senior researcher Dr. Juan Celedon, chief of pulmonary medicine at the UPMC Children’s Hospital of Pittsburgh, said in a news release from the hospital.
Asthma is the most common chronic disease of childhood, affecting about 1 in every 10 kids, according to the National Institutes of Health.
Traditionally, doctors classify asthma into different subtypes based on the immune cells that are causing inflammation that chokes off airways. There’s T2-high driven by T helper 2 cells, T17-high driven by T helper 17 cells, and low-low in which neither type of cell appears to be the cause.
Precisely diagnosing an asthma subtype involves putting a kid under anesthesia and taking a small sample of lung tissue, which is then subjected to genetic analysis, researchers said.
That procedure is so invasive that it’s just not worth it for kids with milder asthma, so doctors instead must guess asthma subtype based on tests of blood, lung function and other allergies, Celedon explained.
“These tests allow us to presume whether a child has T2-high disease or not,” Celedón said. “But they are not 100% accurate, and they cannot tell us whether a child has T17-high or low-low disease. There is no clinical marker for these two subtypes. This gap motivated us to develop better approaches to improve the accuracy of asthma endotype diagnosis.”
For the new study published Jan. 2 in the Journal of the American Medical Association, the researchers collected nasal samples from nearly 460 kids and analyzed them for the presence of eight genes linked to T2 or T17 immune cells.
The samples were drawn from three independent U.S. studies that focused on Puerto Rican and African American children, who have higher rates of asthma and are more likely to die from the disease, researchers said.
The nasal swab analysis accurately revealed the specific subtype of each child’s asthma, results show.
The new test specifically can help steer kids with T2-high asthma to powerful new drugs which target the immune cells that drive the disease, researchers said. As many as 29% of the children had T2-high asthma.
No such treatments yet exist for the other two major subtypes of asthma, Celedon said.
“We have better treatments for T2-high disease, in part, because better markers have propelled research on this endotype,” Celedon said. “But now that we have a simple nasal swab test to detect other endotypes, we can start to move the needle on developing biologics for T17-high and low-low disease.”
The rapid test also could aid other areas of asthma research.
“One of the million-dollar questions in asthma is why some kids get worse as they enter puberty, some stay the same and others get better,” Celedon continued. “Before puberty, asthma is more common in boys, but the incidence of asthma goes up in females in adulthood.”
“Is this related to endotype? Does endotype change over time or in response to treatments? We don’t know. But now that we can easily measure endotype, we can start to answer these questions,” Celedon concluded.