Non-coding RNAs Analysis of Eosinophil Subtypes in Asthma

Chronic airway inflammation rich in eosinophils is an important feature seen in asthma. Airway and blood eosinophilia is associated with increased rates of asthma exacerbations and more intense treatment. Recently, the existence of two distinct eosinophils subtypes was revealed-lung-resident eosinophils (rEOS), which maturate independently to interleukin (IL) 5, with the primary function to maintain tissue homeostasis, and inflammatory eosinophils (iEOS), which mature in IL-5-dependent manner and are mainly involved in immune responses. Eosinophils' effect on the airway remodeling in asthma depends not only on the activity but also by their viable number in the lungs. Blood iEOS infiltrate the airways mainly after the environmental stimulus like allergen and leave the airways with bronchial secretions. However, rEOS reside lung tissue for their entire lifetime regulating local immunity. Blood rEOS and iEOS ratio alters in asthma, compared with healthy controls. It is known that the predominant eosinophils subtype in allergic asthma are iEOS, while rEOS are basic subtype in severe eosinophilic asthma patients, moreover, they are different in adhesive properties and survivability as well. Distinct biological properties allows to speculate about their different functions in asthma, however, there are still little information. Data about differently expressed microRNA (miRNA) profiles in eosinophils in asthma suggests, that eosinophils subtypes can be distinct in non-coding RNA (ncRNA) - microRNA (miRNA), piwi-interacting RNA (piRNA) and long non-coding RNA (IncRNA) profiles that could describe their role in asthma pathogenesis and act as biomarkers to discern asthma phenotypes.