*Study Limitation*

The main limitation of this study is the analysis focused only on HP products in proteins but not lipids or nucleic acids. Furthermore, we did not analyze endogenous or exogenous antioxidants, including genetic polymorphisms [5,10]. However, our study, a pilot in nature, relied on complex analysis, estimating the total harmful effects of ROS on proteins and considering the impacts of all available pro- and antioxidant factors in circulating blood. Furthermore, the CBA assay was measured once; therefore, we cannot assess its variability over time, depending on the course of asthma. Finally, we did not analyze the airway parameters in controls, obviously due to ethical reasons. However, since asthma is a chronic inflammatory lung disease, we believe that our research is valuable and worth publishing. Those factors limit the depth of the investigation but not the study's main findings.
