Blood and Salivary Amphiregulin Levels as Biomarkers for Asthma.

Mahmood Yaseen Hachim,Thenmozhi Venkatachalam,Bassam Mahboub,Noha Mousaad Elemam,Ronald Olivenstein,Qutayba Hamid,Rakhee K Ramakrishnan,Saba Al Heialy,Ibrahim Yaseen Hachim,Rabih Halwani,Laila Salameh,Rifat Hamoudi

doi:10.3389/fmed.2020.561866

Abstract

Background: Amphiregulin (AREG) expression in asthmatic airways and sputum was shown to increase and correlate with asthma. However, no studies were carried out to evaluate the AREG level in blood and saliva of asthmatic patients.Objective: To measure circulating AREG mRNA and protein concentrations in blood, saliva, and bronchial biopsies samples from asthmatic patients.Methods: Plasma and Saliva AREG protein concentrations were measured using ELISA while PBMCs, and Saliva mRNA expression was measured by RT qPCR in non-severe, and severe asthmatic patients compared to healthy controls. Primary asthmatic bronchial epithelial cells and fibroblasts were assessed for AREG mRNA expression and released soluble AREG in their conditioned media. Tissue expression of AREG was evaluated using immunohistochemistry of bronchial biopsies from asthmatic patients and healthy controls. Publicly available transcriptomic databases were explored for the global transcriptomic profile of bronchial epithelium, and PBMCs were explored for AREG expression in asthmatic vs. healthy controls.Results: Asthmatic patients had higher AREG protein levels in blood and saliva compared to control subjects. Higher mRNA expression in saliva and primary bronchial epithelial cells plus higher AREG immunoreactivity in bronchial biopsies were also observed. Both blood and saliva AREG levels showed positive correlations with allergic rhinitis status, atopy status, eczema status, plasma periostin, neutrophilia, Montelukast sodium use, ACT score, FEV1, and FEV1/FVC. In silico analysis showed that severe asthmatic bronchial epithelium with high AREG gene expression is associated with higher neutrophils infiltration.Conclusion: AREG levels measured in a minimally invasive blood sample and a non-invasive saliva sample are higher in non-allergic severe asthma.Clinical ImplicationsThis is the first report to show the higher level of AREG levels in blood and saliva of non-allergic severe asthma.

Highlights

Asthma is characterized by chronic airway inflammation, mucus hyper-production, airway hyper-responsiveness, and variable airway obstruction [1]
We investigated if immune cell populations are different between asthmatic and healthy controls using the transcriptomic expression of the bronchial epithelium to predict the cell type and their state of activation
Other studies focused on AREG expression in sputum [17], damaged bronchial epithelium [41], fibroblasts [42], smooth muscle cells [43, 44] from bronchial biopsies and hematopoietic cells such as eosinophils [19], and basophils [45] in asthma and allergic conditions

Summary

Introduction

Asthma is characterized by chronic airway inflammation, mucus hyper-production, airway hyper-responsiveness, and variable airway obstruction [1]. Amphiregulin (Areg), an EGFR ligand, and a widely expressed transmembrane tyrosine kinase [13, 14], was shown to be upregulated upon inflammation, hormones, growth factors, and xenobiotics stimuli [13]. High AREG expression was related to lung inflammation [15], in damaged lung tissues in patients with chronic obstructive pulmonary disease (COPD) and asthma [16]. AREG expression in structural cells [15] and sputum was associated with asthma severity [17], and it was shown to be increased in airways during an acute asthma attack [18]. Amphiregulin (AREG) expression in asthmatic airways and sputum was shown to increase and correlate with asthma. No studies were carried out to evaluate the AREG level in blood and saliva of asthmatic patients

Methods

Results

Conclusion