Epithelium-derived chemokines induce airway smooth muscle cell migration
ABSTRACT The remodelling of airway smooth muscle (ASM) associated with asthma severity may involve the migration of ASM cells towards the epithelium. However, little is known about the mechanisms of cell migration and the effect of epithelial-derived mediators on this process.
The main objective of the current study is to assess the effects of epithelial-derived chemokines on ASM cell migration.
Normal human ASM cells were incubated with supernatants from cells of the bronchial epithelial cell line BEAS-2B and normal human bronchial epithelial (NHBE) cells. To induce chemokine production, epithelial cells were treated with TNF-alpha. Chemokine expression by epithelial cells was evaluated by quantitative real-time PCR, ELISA and membrane antibody array. To identify the role of individual chemokines in ASM cell migration, we performed migration assays with a modified Boyden chamber using specific neutralizing antibodies to block chemokine effects.
Supernatants from BEAS-2B cells treated with TNF-alpha increased ASM cell migration; migration was increased 1.6 and 2.5-fold by supernatant from BEAS-2B cells treated with 10 and 100 ng/mL TNF-alpha, respectively. Protein levels in supernatants and mRNA expression by BEAS-2B cells of regulated on activation, normal T cell expressed and secreted (RANTES) and IL-8 were significantly increased by 100 ng/mL TNF-alpha treatment. The incubation of supernatant with antibodies to RANTES or IL-8 significantly reduced ASM cell migration, and the combined antibodies further inhibited the cell migration. The migratory effects of supernatants and inhibiting effects of RANTES and/or IL-8 were confirmed also using NHBE cells.
The results show that chemokines from airway epithelial cells cause ASM cell migration and might potentially play a role in the process of airway remodelling in asthma.
SourceAvailable from: Lena Uller[Show abstract] [Hide abstract]
ABSTRACT: Rhinovirus (RV) infections cause exacerbations and development of severe asthma highlighting the importance of antiviral interferon (IFN) defence by airway cells. Little is known about bronchial smooth muscle cell (BSMC) production of IFNs and whether BSMCs have dsRNA-sensing receptors besides TLR3. dsRNA is a rhinoviral replication intermediate and necrotic cell effect mimic that mediates innate immune responses in bronchial epithelial cells. We have explored dsRNA-evoked IFN-β and IFN-λ1 production in human BSMCs and potential involvement of TLR3 and RIG-I-like receptors (RLRs). Primary BSMCs were stimulated with 0.1-10 µg/ml dsRNA, 0.1-1 µg/ml dsRNA in complex with the transfection agent LyoVec (dsRNA/LyoVec; selectively activating cytosolic RLRs) or infected with 0.05-0.5 MOI RV1B. Both dsRNA stimuli evoked early (3 h), concentration-dependent IFN-β and IFN-λ1 mRNA expression, which with dsRNA/LyoVec was much greater, and with dsRNA was much less, after 24 h. The effects were inhibited by dexamethasone. Further, dsRNA and dsRNA/LyoVec concentration-dependently upregulated RIG-I and MDA5 mRNA and protein. dsRNA and particularly dsRNA/LyoVec caused IFN-β and IFN-λ1 protein production (24 h). dsRNA- but not dsRNA/LyoVec-induced IFN expression was partly inhibited by chloroquine that suppresses endosomal TLR3 activation. RV1B dose-dependently increased BSMC expression of RIG-I, MDA5, IFN-β, and IFN-λ1 mRNA. We suggest that BSMCs express functional RLRs and that both RLRs and TLR3 are involved in viral stimulus-induced BSMC expression of IFN-β and IFN-λ1.PLoS ONE 04/2013; 8(4):e62718. DOI:10.1371/journal.pone.0062718 · 3.53 Impact Factor
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ABSTRACT: Structural cell migration plays a central role in the pathophysiology of several diseases, including asthma. Previously, we established that IL-17-induced (CXCL1, CXCL2, and CXCL3) production promoted airway smooth muscle cell (ASMC) migration, and consequently we sought to investigate the molecular mechanism of CXC-induced ASMC migration. Recombinant human CXCL1, CXCL2, and CXCL3 were used to assess migration of human primary ASMCs from normal and asthmatic subjects using a modified Boyden chamber. Neutralizing Abs or small interfering RNA (siRNA) knockdown and pharmacological inhibitors of PI3K, ERK1/2, and p38 MAPK pathways were used to investigate the receptors and the signaling pathways involved in CXC-induced ASMC migration, respectively. We established the ability of CXCL2 and CXCL3, but not CXCL1, to induce ASMC migration at the tested concentrations using normal ASMCs. We found CXCL2-induced ASMC migration to be dependent on p38 MAPK and CXCR2, whereas CXCL3-induced migration was dependent on p38 and ERK1/2 MAPK pathways via CXCR1 and CXCR2. While investigating the effect of CXCL2 and CXCL3 on asthmatic ASMC migration, we found that they induced greater migration of asthmatic ASMCs compared with normal ones. Interestingly, unlike normal ASMCs, CXCL2- and CXCL3-induced asthmatic ASMC migration was mainly mediated by the PI3K pathway through CXCR1. In conclusion, our results establish a new role of CXCR1 in ASMC migration and demonstrate the diverse mechanisms by which CXCL2 and CXCL3 mediate normal and asthmatic ASMC migration, suggesting that they may play a role in the pathogenesis of airway remodeling in asthma.The Journal of Immunology 07/2013; 191(5). DOI:10.4049/jimmunol.1203421 · 5.36 Impact Factor
Article: Mechanisms of Airway Remodeling[Show abstract] [Hide abstract]
ABSTRACT: Airway remodeling comprises the structural changes of airway walls, induced by repeated injury and repair processes. It is characterized by the changes of tissue, cellular, and molecular composition, affecting airway smooth muscle, epithelium, blood vessels, and extracellular matrix. It occurs in patients with chronic inflammatory airway diseases such as asthma, COPD, bronchiectasis, and cystic fibrosis. Airway remodeling is arguably one of the most intractable problems in these diseases, leading to irreversible loss of lung function. Current therapeutics can ameliorate inflammation, but there is no available therapy proven to prevent or reverse airway remodeling, although reversibility of airway remodeling is suggested by studies in animal models of disease. Airway remodeling is often considered the result of longstanding airway inflammation, but it may be present to an equivalent degree in the airways of children with asthma, raising the necessity for early and specific therapeutic interventions. In this review, we consider the factors that may contribute to airway remodeling and discuss the current and potential therapeutic interventions.Chest 09/2013; 144(3):1026-32. DOI:10.1378/chest.12-3073 · 7.13 Impact Factor