Gene expression networks in COPD: microRNA and mRNA regulation.
ABSTRACT The mechanisms underlying chronic obstructive pulmonary disease (COPD) remain unclear. MicroRNAs (miRNAs or miRs) are small non-coding RNA molecules that modulate the levels of specific genes and proteins. Identifying expression patterns of miRNAs in COPD may enhance our understanding of the mechanisms of disease. A study was undertaken to determine if miRNAs are differentially expressed in the lungs of smokers with and without COPD. miRNA and mRNA expression were compared to enrich for biological networks relevant to the pathogenesis of COPD.
Lung tissue from smokers with no evidence of obstructive lung disease (n=9) and smokers with COPD (n=26) was examined for miRNA and mRNA expression followed by validation. We then examined both miRNA and mRNA expression to enrich for relevant biological pathways.
70 miRNAs and 2667 mRNAs were differentially expressed between lung tissue from subjects with COPD and smokers without COPD. miRNA and mRNA expression profiles enriched for biological pathways that may be relevant to the pathogenesis of COPD including the transforming growth factor β, Wnt and focal adhesion pathways. miR-223 and miR-1274a were the most affected miRNAs in subjects with COPD compared with smokers without obstruction. miR-15b was increased in COPD samples compared with smokers without obstruction and localised to both areas of emphysema and fibrosis. miR-15b was differentially expressed within GOLD classes of COPD. Expression of SMAD7, which was validated as a target for miR-15b, was decreased in bronchial epithelial cells in COPD.
miRNA and mRNA are differentially expressed in individuals with COPD compared with smokers without obstruction. Investigating these relationships may further our understanding of the mechanisms of disease.
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ABSTRACT: A growing body of evidence indicates that aberrant activation of alveolar epithelial cells and fibroblasts in an aging lung plays a critical role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, the biopathological processes linking aging with IPF and the mechanisms responsible for the abnormal activation of epithelial cells and fibroblasts have not been elucidated. Many of the hallmarks of aging e.g., genomic instability, telomere attrition, epigenetic alterations, mitochondrial dysfunction, and cellular senescence, have been proposed as essential mechanisms for the development of IPF; however these disturbances are not restricted to IPF and also occur in other aging-related lung disorders, primarily chronic obstructive lung disease (COPD). Therefore, an unanswered question is why a current/former smoker of about 60 years old with shorter telomeres, alveolar epithelial senescence, excessive oxidative stress and mitochondrial dysfunction develops IPF and not COPD; in other words, what makes old lungs specifically susceptible to develop IPF? In this Perspective we propose an integral model in which the combination of some gene variants and/or gene expression in the aging lung, results in the loss of epithelial integrity and consequently in the failure of the alveoli to correctly respond to injury and to face the stress associated with mechanical stretch. Afterward, a distinctive epigenetic "reprogramming" that affects both epithelial cells and fibroblasts provoke, among others, the recapitulation of developmental pathways, and the aberrant activation and miscommunication between both cell types resulting in the exaggerated production and accumulation of extracellular matrix and the subsequent destruction of the lung architecture.American Journal of Respiratory and Critical Care Medicine 03/2014; · 11.04 Impact Factor
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ABSTRACT: Heavy smoking is associated with the development of chronic obstructive pulmonary disease (COPD). However, there is no valuable biomarker for evaluating COPD development in heavy smokers because they are usually asymptomatic. This study is aimed at evaluating whether the levels of serum miRNAs can serve as biomarkers for predicting the occurrence of COPD. A rat model of emphysema was induced by enforced smoking, and the dynamic miRNAs expression profile at different stages of emphysema with varying periods of smoking were analyzed by microarray and quantitative real-time polymerase chain reaction (qRT-PCR). The differentially expressing miRNAs were analyzed using Gene Ontology and the KEGG PATHWAY database. The levels of three serum candidate miRNAs were measured by qRT-PCR in 41 healthy controls (HC), 40 asymptomatic heavy smokers, and 49 COPD patients. Following smoking for varying periods, different severities of lung emphysema were observed in different groups of rats, accompanied by altered levels of some serum miRNAs associated with regulating some pathways. Furthermore, the levels of miR-21 were significantly higher in the COPD patients and asymptomatic heavy smokers than in the HC (P < 0.001), while the levels of miR-181a were significantly lower in the COPD patients and asymptomatic heavy smokers than in the HC (P < 0.001). Accordingly, the levels of serum miR-21 and miR-181a as well as their ratios had a high sensitivity (0.854) and specificity (0.850) for evaluating the development of COPD. Our data suggest that the levels of serum miR-21 and miR-181a may be valuable for evaluating the development of COPD in heavy smokers.Molecular BioSystems 02/2014; · 3.35 Impact Factor
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ABSTRACT: Introduction: Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide. The growing burden of COPD is due to continuous tobacco use, which is the most important risk factor of the disease, indoor fumes, occupational exposures and also aging of the world's population. Epigenetic mechanisms significantly contribute to COPD pathophysiology. Areas covered: This review focuses on disease-relevant changes in DNA modification, histone modification and non-coding RNA expression in COPD, and provides insight into novel therapeutic approaches modulating epigenetic mechanisms. Recent findings revealed, among others, globally changed DNA methylation patterns, decreased levels of histone deacetylases and reduced microRNAs levels in COPD. The authors also discuss a potential role of the chromatin silencing Polycomb group of proteins in COPD. Expert opinion: COPD is a highly complex disease and therapy development is complicated by the fact that many smokers develop both COPD and lung cancer. Of interest, combination therapies involving DNA methyltransferase inhibitors and anti-inflammatory drugs provide a promising approach, as they might be therapeutic for both COPD and cancer. Although the field of epigenetic research has virtually exploded over the last 10 years, particular efforts are required to enhance our knowledge of the COPD epigenome in order to successfully establish epigenetic-based therapies for this widespread disease.Expert Opinion on Drug Discovery 06/2014; 9(6):609-28. · 2.30 Impact Factor