Profiling of healthy and asthmatic airway smooth muscle cells following interleukin-1β treatment: a novel role for CCL20 in chronic mucus hypersecretion

Abstract

Chronic mucus hypersecretion (CMH) contributes to the morbidity and mortality of asthma, and remains uncontrolled by current therapies in the subset of patients with severe, steroid-resistant disease. Altered cross-talk between airway epithelium and airway smooth muscle cells (ASMCs), driven by pro-inflammatory cytokines such as interleukin (IL)-1β, provides a potential mechanism that influences CMH. This study investigated mechanisms underlying CMH by comparing IL-1β-induced gene expression profiles between asthma and control-derived ASMCs and the subsequent paracrine influence on airway epithelial mucus production IL-1β-treated ASMCs from asthmatic patients and healthy donors were profiled using microarray analysis and ELISA. Air-liquid interface (ALI)-cultured CALU-3 and primary airway epithelial cells were treated with identified candidates and mucus production assessed.The IL-1β-induced expression and protein release was increased in ASMCs from moderate compared with mild asthmatic patients and healthy controls IL-1β induced lower expression in asthma-derived ASMCs compared with controls. Decreased expression was validated in bronchial biopsies from 16 asthmatic patients 39 healthy donors. miR-146a-5p overexpression abrogated CCL20 release in ASMCs. CCL20 treatment of ALI-cultured CALU-3 and primary airway epithelial cells induced mucus production, while CCL20 levels in sputum were associated with increased levels of CMH in asthmatic patients.Elevated CCL20 production by ASMCs, possibly resulting from dysregulated expression of the anti-inflammatory miR-146a-5p, may contribute to enhanced mucus production in asthma.

Airway smooth muscle may drive mucus hypersecretion in asthma

“…CCL20 has been identified also as a product of airway epithelial cells exposed to particulates and its secretion is mitogen-activated protein kinase dependent [11]. It is elevated in the sputum of subjects with chronic obstructive pulmonary disease but in this context has been linked to increase in dendritic cell numbers in the airways [12] and not linked to mucus hypersecretion as suggested in the current article by FAIZ et al [8]. Whether the ASM cells have a greater capacity to secrete CCL20 than epithelial cells and whether the site of action on its receptor CCR6 is at the basolateral rather than apical surface requires further exploration.…”

“…Although the current study by FAIZ et al [8] provides insights into another potential property of ASM cells with relevance to asthma, confirmation in intact humans of the implications of findings from the current study and other reductionist experiments is required. Administration of an appropriate antagonist, even if it reduces sputum volume, will not determine the cells of origin of CCL20.…”

“…In the current issue of the European Respiratory Journal, FAIZ et al [8] describe an elegant series of studies using in vitro techniques to study the effects of interleukin (IL)-1β on ASM cells, coupled with the analysis of sputum samples from human asthmatics, which have led to the conclusion that ASM cells contribute to mucus hypersecretion by the epithelium. An examination of gene expression profiles of ASM cells harvested from asthmatic and healthy subjects stimulated with IL-1β revealed that CCL20 and MIR146A were among the genes whose expression was affected by the cytokine.…”

“…MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression through binding to the 3ʹ untranslated region of targeted mRNAs to inhibit protein translation or degradation of mRNAs. miR-146a-5p, which was focused upon by FAIZ et al [8], has been identified in prior publications as an anti-inflammatory miRNA that inhibits the NF-κB downstream signalling molecules IRAK1 and TRAF6 [9] and has been associated with a variety of cancers, including bronchogenic carcinoma. ASM cells harvested from asthmatics stimulated by a combination of cytokines (tumour necrosis factor (TNF)-α, IL-1β and interferon-γ; so-called cytomix) have been previously shown to express higher levels of miR-146-5p than control cells and to negatively regulate IL-1β and cyclooxygenase-2 synthesis [10].…”

Neonatal genetics of gene expression reveal the origins of autoimmune and allergic disease risk

“…At the CCL20 locus, the reQTL (rs13034664) in PHA-stimulated T cells colocalised with childhoodonset asthma 41 (Figure 4A, Figure S6). CCL20 encodes a C-C chemokine ligand that binds to a G protein-coupled receptor, and elevated CCL20 expression has been shown in airways of patients with chronic obstructive pulmonary disease (COPD) 42 and asthma 43,44 . CCL20 induces mucin production by binding to its unique receptor (CCR6) in human airway epithelial cells 45 .…”