*2.1. Study Participants*

We investigated 74 asthma patients enrolled at the Outpatient Clinic of the Allergy and Clinical Immunology Department, University Hospital, Krakow, Poland. Diagnosis of asthma and disease severity (mild, moderate, and severe disease) was established based on the current Global Initiative for Asthma (GINA) guideline [1]. In addition, asthma symptom control was assessed based on the Asthma Control Test (ACT) result (wellcontrolled, not well-controlled, and very poorly controlled asthma). More details on that issue, including definitions of asthma severity and symptom control grading, are provided in the Supplementary Table S1.

The study was carried out while following the Declaration of Helsinki and the Ethics Committee of Jagiellonian University approved the protocol (approval number: KBET/151/B/2013). Furthermore, all subjects gave written informed consent to participate in the study.
