A diagnostic blood test for asthma may be on the way

Researchers have found unique microRNAs (miRNAs) in the blood of people with asthma, which could be used as biomarkers for the first diagnostic blood test for the condition, according to an article published online in the Journal of Allergy and Clinical Immunology.

The miRNA biomarkers could also be used to develop more targeted asthma treatments, the researchers predicted.

“The role of miRNAs in asthma is not well understood, although it looks as though these molecules play very important roles in inflammation and in immune responses,” said Faoud T. Ishmael, MD, PhD, Associate Professor of Medicine and Biochemistry and Molecular Biology at Penn State College of Medicine, in Hershey, PA.

In this study, Dr. Ishmael and colleagues measured miRNAs in the blood of 79 subjects—including 35 patients with asthma, 25 patients with allergic rhinitis but no asthma, and 19 patients with no asthma and no allergic rhinitis.

The researchers identified 30 miRNAs that were differentially expressed in asthmatic, allergic, and healthy subjects, with different expression patterns among the three patient groups. Based on these patterns, they were able to predict with 91% accuracy whether a person had asthma.

“We found that there was a subset of these miRNAs that were unique to asthma, and that we could use them to predict if someone had it based on if they were high or low compared to the other two groups,” Dr. Ishmael said. “There’s a different molecular fingerprint if you have asthma compared to if you have allergic rhinitis or neither.”

In asthmatic patients, miRNA expression profiles identified 2 subtypes that differed by high or low levels of eosinophils.

“Eosinophils play very important roles in some kind of allergic reactions, and they might have implications for how people respond to some of the treatments that are already on the market for asthma,” Dr. Ishmael said.

“We think this may be useful technology to distinguish between some of these different subtypes, so we know from the beginning when a treatment won’t work for a patient,” he added.

The researchers hope that this discovery will eventually lead to new asthma treatments. For now, the researchers are gathering a larger cohort to confirm that the miRNA testing is truly diagnostic for asthma.

“Our goal is to have a blood test for asthma developed in the next 5 years,” Dr. Ishmael said. “You might be able to take a drop of blood from a finger stick and analyze it in the clinic to determine whether someone has asthma at that visit. That would be the ultimate goal.”