Patterns of MicroRNA Expression Distinguish Patients with Asthma and Allergic Rhinitis

Subsets of circulating micro RNAs (miRNAs) are uniquely expressed in asthmatic patients and in patients with allergic rhinitis (AR) and have potential for use as noninvasive biomarkers to diagnose and characterize these diseases.

MicroRNAs are a class of about 20 nucleotides-long RNA fragments that block gene expression by attaching to molecules of messenger RNA in a fashion that prevents them from transmitting the protein synthesizing instructions they had received from the DNA. With their capacity to fine-tune protein expression via sequence-specific interactions, miRNAs help regulate cell maintenance and differentiation.

Investigators at the Pennsylvania State College of Medicine (Hershey, USA) sought to determine whether miRNAs were differentially expressed in the blood of asthmatic patients compared with those in the blood of nonasthmatic patients with AR and nonallergic nonasthmatic subjects. Furthermore, they sought to establish whether miRNAs could be used to characterize or subtype asthmatic patients.

To these ends, they used real-time quantitative PCR to measure expression of plasma miRNAs in 35 asthmatic patients, 25 nonasthmatic patients with AR, and 19 nonallergic nonasthmatic subjects.

Results revealed 30 miRNAs that were differentially expressed among healthy, allergic, and asthmatic subjects. These miRNAs fit into five different expression pattern groups. Among asthmatic patients, miRNA expression profiles identified two subtypes that differed by high or low peripheral eosinophil levels. Circulating miR-125b, miR-16, miR-299-5p, miR-126, miR-206, and miR-133b levels were most predictive of allergic and asthmatic status.

"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 senior author Dr. Faoud Ishmael, associate professor of medicine, biochemistry, and molecular biology at Pennsylvania State College of Medicine.

"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," said Dr. Ishmael. "There is a different molecular fingerprint if you have asthma compared to if you have allergic rhinitis or neither.

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. We think this may be useful technology to distinguish between some of these different sub-types so we know from the beginning when a treatment will not work for a patient."

The study was published in the March 26, 2016, online edition of The Journal of Allergy and Clinical Immunology.

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