Expression of eosinophil β chain-signaling cytokines receptors, outer-membrane integrins, and type 2 inflammation biomarkers in severe non-allergic eosinophilic asthma

Abstract

Background Severe non-allergic eosinophilic asthma (SNEA) is a rare asthma phenotype associated with severe clinical course, frequent exacerbations, and resistance to therapy, including high steroid doses. The key feature is type 2 inflammation with predominant airway eosinophilia. Eosinophil maturation, activation, survivability, and recruitment are mainly induced by interleukin (IL)-3, IL-5 and granulocyte–macrophage colony-stimulating factor (GM-CSF) through their receptors on eosinophil surface and related with integrins activation states. The aim of the study was to estimate the expression of eosinophil β chain-signaling cytokines receptors, outer-membrane integrins, and serum-derived type 2 inflammation biomarkers in SNEA. Methods We examined 8 stable SNEA patients with high inhaled steroid doses, 12 steroid-free patients with non-severe allergic asthma (AA), 12 healthy subjects (HS). Blood eosinophils were isolated using Ficol gradient centrifugation and magnetic separation. Eosinophils were lysed, and mRNA was isolated. Gene expressions of IL-5Rα, IL-3Rα, GM-CSFRα, and α4β1, αMβ2 integrins were analyzed using quantitative real-time reverse transcription polymerase chain reaction. Type 2 inflammation activity was evaluated measuring exhaled nitric oxide concentration (FeNO) collected with the electrochemical sensing device. Serum IL-5, IL-3, GM-CSF, periostin, chemokine ligand (CCL) 17 and eotaxin concentrations were assessed by enzyme-linked immunosorbent assay. Results Eosinophils from SNEA patients demonstrated significantly increased gene expression of IL-3Rα, IL-5Rα and GM-CSFRα as well as α4, β1 and αM integrin subunits compared with the AA group. The highest IL-5 serum concentration was in the SNEA group; it significantly differed compared with AA and HS. GM-CSF serum levels were similar in the SNEA and AA groups and were significantly lower in the HS group. No differences in serum IL-3 concentration were found among all groups. Furthermore, serum levels of eotaxin, CCL17 and FeNO, but not periostin, differed in all groups, with the highest levels in SNEA patients. Conclusions Eosinophil demonstrated higher expression of IL-3, IL-5, GM-CSF α-chain receptors and α4, β1, αM integrins subunits in SNEA compared with the AA group. Additionally, SNEA patients had increased serum levels of IL-5, eotaxin and CCL-17. Trial registration ClinicalTrials.gov Identifier NCT03388359.

In Vivo Allergen-Activated Eosinophils Promote Collagen I and Fibronectin Gene Expression in Airway Smooth Muscle Cells via TGF-β1 Signaling Pathway in Asthma

“…It was shown that eosinophils have various integrins, but the two heterodimers (αMβ2 and α4β1) are the most important integrins in migration as they recognize the adhesion molecules of pulmonary structural cells and are dysregulated in asthma [31]. In our previous publications, we showed that AA eosinophils had higher outer membrane integrins αMβ2 and α4β1 gene expression compared to HS [27,32]. It shows that AA eosinophils are more activated as the molecules that are responsible for adherence are upregulated, and it helps eosinophils to migrate through the wall of vessels and continue the movement to bronchial tissue interacting with pulmonary structural cells and ECM proteins.…”

“…Eotaxins induce eosinophil degranulation and release of biologically active mediators through the activation of ERK2 and p38 MAPK signaling [57]. In the previous study, we showed that the level of eotaxins was increased in serum collected from AA patients compared to HS [27]. We presume that an increased level of eotaxins induces TGF-β transcription in blood eosinophils.…”

“…The maturation of eosinophils is activated in bone marrow, and they are recruited to the airways to cope with environmental triggers that lead to inflammation. These processes are associated with type 2 inflammation as the airway epithelial cells release alarmins such as interleukin (IL) 25, IL-33, and thymic stromal lymphopoietin (TSLP), which activate innate and humoral immune system [24][25][26][27]. Inhaled allergens sensitize dendritic cells that stimulate the proliferation of T helper type 2 (Th2) cells and subsequent release of cytokines that include IL-4, IL-5, IL-13 [4,27].…”

The role of eosinophilopoietins and integrins on eosinophils biology in asthma

“…Previously was demonstrated that gene expression of αM, β 2 , α 4 , and β 1 integrins subunits are enhanced in eosinophils from stable AA patients [36]. Moreover, another study revealed that αM, α 4 , and β 1 subunits are differently expressed in SNEA patients, compared with AA [32]. Altered integrins expression suggest their potential role as a target for eosinophilic inflammation treatment in asthma.…”

“…This study was completed with healthy subjects eosinophils. eral chemoattractants [12,34]. Whereby integrins on circulating eosinophils become activated, eosinophils tether inflow, and roll on bronchial endothelial cells (Figure 4).…”