Nasal Swab Can Easily Identify Asthma Subtypes

Worldwide, asthma is the most common chronic respiratory illness that affects children, particularly Puerto Rican and Black youths, who experience higher rates of asthma and asthma-related deaths compared to white youths. A recent study focused on these disproportionately affected children, and it has shown that a nasal swab is able to distinguish between subtypes of asthma. These findings, which have been reported in JAMA, could help improve asthma treatments.

There are classes of asthma known as endotypes, which are called T2-high or T2-low; cases are classified based on the level of inflammation from helper T2 cells. When T2 immune responses lead to high serum levels of T2 cytokines, T2-high asthma results, but when T2 cytokines levels are low, it is T2-low asthma.

“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," explained senior study author Juan Celedón, MD, Dr.P.H., a professor of pediatrics at the University of Pittsburgh and chief of pulmonary medicine at UPMC Children’s Hospital of Pittsburgh.

Recently, T2-low asthma has also been subdivided into T17-high, where T2 helper inflammation is low and T17 helper inflammation is high; or low-low that has lower levels of both inflammation types. Usually, a genetic analysis of lung tissue is necessary to distinguish between these endotypes of asthma. But this procedure is not suitable for children, especially when their asthma is mild. As such, immune markers are used to make determinations, sometimes in imperfect ways.

While those tests can give some indication of the type of asthma a child has, they are not totally accurate. There is also no simple test for the T17-high or low-low subtypes, noted Celedón. “This gap motivated us to develop better approaches to improve the accuracy of asthma endotype diagnosis.”

In this work, almost 500 nasal samples were collected from children participating in various asthma studies. The researchers assessed the expression of different genes linked to T2 and T17 inflammation.

The nasal swab analysis was able to identify each patient’s endotype. Now, this work could help improve treatments for the various types of asthma, or help advance asthma research.

“We have better treatments for T2-high disease, in part, because better markers have propelled research on this endotype,” said Celedón. “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.”

Celedón noted that endotypes could help scientists answer some questions about asthma, such as why in some cases, asthma improves when puberty starts, but in others there is no change, while some get worse.

Sources: University of Pittsburgh Medical Center, JAMA