Downregulation of the serum response factor/miR-1 axis in the quadriceps of patients with COPD

Noncoding RNAs in chronic obstructive pulmonary disease: From pathogenesis to therapeutic targets

Chronic obstructive pulmonary disease (COPD) is the most prevalent chronic respiratory disorder that is becoming the leading cause of morbidity and mortality on a global scale. There is an unmet need to investigate the underlying pathophysiological mechanisms and unlock novel therapeutic avenues for COPD. Recent research has shed light on the significant roles played by diverse noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), in orchestrating the development and progression of COPD. This review provides an overview of the regulatory roles of ncRNAs in COPD, elucidating their underlying mechanisms, and illuminating the potential prospects of RNA-based therapeutics in the management of COPD.

The Effect of Physical Activity/Exercise on miRNA Expression and Function in Non-Communicable Diseases-A Systematic Review

Exercise may differently affect the expression of key molecular markers, including skeletal muscle and circulating miRNAs, involved in cellular and metabolic pathways' regulation in healthy individuals and in patients suffering from non-communicable diseases (NCDs). Epigenetic factors are emerging as potential therapeutic biomarkers in the prognosis and treatment of NCDs and important epigenetic factors, miRNAs, play a crucial role in cellular pathways. This systematic review aims to underline the potential link between changes in miRNA expression after different types of physical activity/exercise in some populations affected by NCDs. In June 2023, we systematically investigated the following databases: PubMed, MEDLINE, Scopus, and Web of Science, on the basis of our previously established research questions and following the PRISMA guidelines. The risk of bias and quality assessment were, respectively, covered by ROB2 and the Newcastle Ottawa scale. Of the 1047 records extracted from the initial search, only 29 studies were found to be eligible. In these studies, the authors discuss the association between exercise-modulated miRNAs and NCDs. The NCDs included in the review are cancer, cardiovascular diseases (CVDs), chronic obstructive pulmonary disease (COPD), and type 2 diabetes mellitus (T2DM). We evidenced that miR-146, miR-181, miR-133, miR-21, and miRNA-1 are the most reported miRNAs that are modulated by exercise. Their expression is associated with an improvement in health markers and they may be a potential target in terms of the development of future therapeutic tools.

Increased Expression of MiRNA-1 Contributes to Hypobaric Hypoxia-Induced Skeletal Muscle Loss

The present study aims to analyze the role of microRNA-1 in the regulation of skeletal muscle loss under hypobaric hypoxia (HH). Male Sprague Dawley rats (n = 10) weighing 230-250 g are divided into two groups, control and HH exposure for 7 days at 25 000 ft. After the hypoxia exposure, the animals are sacrificed and hindlimb skeletal muscles are excised for further analysis. Studies found the potential role of miR-1 (myomiR) as a biomarker under different atrophic conditions. Prolonged exposure to HH leads to enhanced expression of miR-1 in skeletal muscle as compared to unexposed controls. The Bioinformatics approach is used to identify the validated targets and the biological processes of miR-1. The target prediction tools identify PAX3 and HSP70 as major targets for miR-1. Exposure to HH significantly reduces PAX3 and HSP70 expression during 7 days of HH exposure, which further enhances the activity of FOXO3, MSTN, and ATROGIN known for the progression of skeletal muscle atrophy in relation to control rats. This study indicates the increased expressions of miR-1 and reduced expression of PAX3 and HSP70 lead to impaired myogenesis in skeletal muscle under HH. Further, enhanced expression of muscle degradation genes such as FOXO3, MSTN, and ATROGIN under HH exposure causes skeletal muscle protein loss.

Revisiting Skeletal Muscle Dysfunction and Exercise in Chronic Obstructive Pulmonary Disease: Emerging Significance of Myokines

Skeletal muscle dysfunction (SMD) is the most significant extrapulmonary complication and an independent prognostic indicator in patients with chronic obstructive pulmonary disease (COPD). Myokines, such as interleukin (IL)-6, IL-15, myostatin, irisin, and insulin-like growth factor (IGF)-1, play important roles in skeletal muscle mitochondrial function, protein synthesis and breakdown balance, and regeneration of skeletal muscles in COPD. As the main component of pulmonary rehabilitation, exercise can improve muscle strength, muscle endurance, and exercise capacity in patients with COPD, as well as improve the prognosis of SMD and COPD by regulating the expression levels of myokines. The mechanisms by which exercise regulates myokine levels are related to microRNAs. IGF-1 expression is upregulated by decreasing the expression of miR-1 or miR-29b. Myostatin downregulation and irisin upregulation are associated with increased miR-27a expression and decreased miR-696 expression, respectively. These findings suggest that myokines are potential targets for the prevention and treatment of SMD in COPD. A comprehensive analysis of the role and regulatory mechanisms of myokines can facilitate the development of new exercise-based therapeutic approaches for patients with COPD.

Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.

Profiling of Chromatin Accessibility in Pigs across Multiple Tissues and Developmental Stages

The study of chromatin accessibility across tissues and developmental stages is essential for elucidating the transcriptional regulation of various phenotypes and biological processes. However, the chromatin accessibility profiles of multiple tissues in newborn pigs and across porcine liver development remain poorly investigated. Here, we used ATAC-seq and rRNA-depleted RNA-seq to profile open chromatin maps and transcriptional features of heart, kidney, liver, lung, skeletal muscle, and spleen in newborn pigs and porcine liver tissue in the suckling and adult stages, respectively. Specifically, by analyzing a union set of protein-coding genes (PCGs) and two types of transcripts (lncRNAs and TUCPs), we obtained a comprehensive annotation of consensus ATAC-seq peaks for each tissue and developmental stage. As expected, the PCGs with tissue-specific accessible promoters had active transcription and were relevant to tissue-specific functions. In addition, other non-coding tissue-specific peaks were involved in both physical activity and the morphogenesis of neonatal tissues. We also characterized stage-specific peaks and observed a close association between dynamic chromatin accessibility and hepatic function transition during liver postnatal development. Overall, this study expands our current understanding of epigenetic regulation in mammalian tissues and organ development, which can benefit both economic trait improvement and improve the biomedical usage of pigs.

An alternative mechanism for skeletal muscle dysfunction in long-term post-viral lung disease

Chronic lung disease is often accompanied by disabling extrapulmonary symptoms, notably skeletal muscle dysfunction and atrophy. Moreover, the severity of respiratory symptoms correlates with decreased muscle mass and in turn lowered physical activity and survival rates. Previous models of muscle atrophy in chronic lung disease often modeled chronic obstructive pulmonary disease (COPD) and relied on cigarette smoke exposure and LPS stimulation, but these conditions independently affect skeletal muscle even without accompanying lung disease. Moreover, there is an emerging and pressing need to understand the extrapulmonary manifestations of long-term post-viral lung disease (PVLD) as found in COVID-19. Here, we examine the development of skeletal muscle dysfunction in the setting of chronic pulmonary disease caused by infection due to the natural pathogen Sendai virus using a mouse model of PVLD. We identify a significant decrease in myofiber size when PVLD is maximal at 49 days after infection. We find no change in the relative types of myofibers, but the greatest decrease in fiber size is localized to fast-twitch-type IIB myofibers based on myosin heavy chain immunostaining. Remarkably, all biomarkers of myocyte protein synthesis and degradation (total RNA, ribosomal abundance, and ubiquitin-proteasome expression) were stable throughout the acute infectious illness and chronic post-viral disease process. Together, the results demonstrate a distinct pattern of skeletal muscle dysfunction in a mouse model of long-term PVLD. The findings thereby provide new insights into prolonged limitations in exercise capacity in patients with chronic lung disease after viral infections and perhaps other types of lung injury.NEW & NOTEWORTHY Our study used a mouse model of post-viral lung disease to study the impact of chronic lung disease on skeletal muscle. The model reveals a decrease in myofiber size that is selective for specific types of myofibers and an alternative mechanism for muscle atrophy that might be independent of the usual markers of protein synthesis and degradation. The findings provide a basis for new therapeutic strategies to correct skeletal muscle dysfunction in chronic respiratory disease.

Main Pathogenic Mechanisms and Recent Advances in COPD Peripheral Skeletal Muscle Wasting

Chronic obstructive pulmonary disease (COPD) is a worldwide prevalent respiratory disease mainly caused by tobacco smoke exposure. COPD is now considered as a systemic disease with several comorbidities. Among them, skeletal muscle dysfunction affects around 20% of COPD patients and is associated with higher morbidity and mortality. Although the histological alterations are well characterized, including myofiber atrophy, a decreased proportion of slow-twitch myofibers, and a decreased capillarization and oxidative phosphorylation capacity, the molecular basis for muscle atrophy is complex and remains partly unknown. Major difficulties lie in patient heterogeneity, accessing patients' samples, and complex multifactorial process including extrinsic mechanisms, such as tobacco smoke or disuse, and intrinsic mechanisms, such as oxidative stress, hypoxia, or systemic inflammation. Muscle wasting is also a highly dynamic process whose investigation is hampered by the differential protein regulation according to the stage of atrophy. In this review, we report and discuss recent data regarding the molecular alterations in COPD leading to impaired muscle mass, including inflammation, hypoxia and hypercapnia, mitochondrial dysfunction, diverse metabolic changes such as oxidative and nitrosative stress and genetic and epigenetic modifications, all leading to an impaired anabolic/catabolic balance in the myocyte. We recapitulate data concerning skeletal muscle dysfunction obtained in the different rodent models of COPD. Finally, we propose several pathways that should be investigated in COPD skeletal muscle dysfunction in the future.

The role of muscle-specific MicroRNAs in patients with chronic obstructive pulmonary disease and skeletal muscle dysfunction

Skeletal muscle dysfunction is a systematic manifestation of chronic obstructive pulmonary disease (COPD), which is manifested through the changes in the respiratory and peripheral muscle fiber types, reducing muscle strength and endurance, and muscle atrophy. Muscle dysfunction limits the daily mobility, negatively affects the quality of life, and may increase the patient’s risk of mortality. MicroRNAs (miRNAs) as the regulators of gene expression, plays an important role in modulating skeletal muscle dysfunction in COPD by regulating skeletal muscle development (proliferation, differentiation), protein synthesis and degradation, inflammatory response, and metabolism. In particular, muscle-specific miRNAs (myomiRs) may play an important role in this process, although the different expression levels of myomiRs in COPD and skeletal muscle dysfunction and the mechanisms underlying their role remain unclear. In this paper, we review the differential expression of the myomiRs in COPD to identify myomiRs that play a role in skeletal muscle dysfunction in COPD. We further explore their possible mechanisms and action in order to provide new ideas for the prevention and treatment of the skeletal muscle dysfunction in COPD.

An alternative mechanism for skeletal muscle dysfunction in long-term post-viral lung disease

Chronic lung disease is often accompanied by disabling extrapulmonary symptoms, notably skeletal muscle dysfunction and atrophy. Moreover, the severity of respiratory symptoms correlates with decreased muscle mass and in turn lowered physical activity and survival rates. Previous models of muscle atrophy in chronic lung disease often modeled COPD and relied on cigarette smoke exposure and LPS-stimulation, but these conditions independently affect skeletal muscle even without accompanying lung disease. Moreover, there is an emerging and pressing need to understand the extrapulmonary manifestations of long-term post-viral lung disease (PVLD) as found in Covid-19. Here, we examine the development of skeletal muscle dysfunction in the setting of chronic pulmonary disease using a mouse model of PVLD caused by infection due to the natural pathogen Sendai virus. We identify a significant decrease in myofiber size when PVLD is maximal at 49 d after infection. We find no change in the relative types of myofibers, but the greatest decrease in fiber size is localized to fast-twitch type IIB myofibers based on myosin heavy chain immunostaining. Remarkably, all biomarkers of myocyte protein synthesis and degradation (total RNA, ribosomal abundance, and ubiquitin-proteasome expression) were stable throughout the acute infectious illness and chronic post-viral disease process. Together, the results demonstrate a distinct pattern of skeletal muscle dysfunction in a mouse model of long-term PVLD. The findings thereby provide new insight into prolonged limitations in exercise capacity in patients with chronic lung disease after viral infections and perhaps other types of lung injury.

Elevated mir-145-5p is associated with skeletal muscle dysfunction and triggers apoptotic cell death in C2C12 myotubes

Skeletal muscle dysfunction is a common comorbidity of chronic obstructive pulmonary disease (COPD), and the molecular mechanisms regarding to the pathogenesis of this disease have not been elucidated. In this study, a novel miR-145-5p was significantly upregulated in the serum collected from patients with COPD-associated muscle atrophy, in contrast with the normal participants. Then, we evidenced that silencing of miR-145-5p suppressed cell death and elongated cell survival during cell culture process. Consistently, upregulation of miR-145-5p induced cell apoptosis and restrain cell viability in the C2C12 cells, suggesting that miR-145-5p contributes to cell death. Further experiments evidenced that miR-145-5p decreased the expression levels of phosphorylated PI3K (p-PI3K), Akt (p-Akt) and mTOR (p-mTOR) to inactivate the PI3K/Akt/mTOR pathway, and this pathway was also reactivated by miR-145-5p ablation. Finally, we proved that the protective effects of miR-145-5p ablation were abrogated by co-treating cells with PI3K inhibitor LY294002. Taken together, we concluded that miR-145-5p promoted cell death to facilitate muscle dysfunctions via inactivating the PI3K/Akt/mTOR pathway.

Non-coding RNA basis of muscle atrophy

Muscle atrophy is a common complication of many chronic diseases including heart failure, cancer cachexia, aging, etc. Unhealthy habits and usage of hormones such as dexamethasone can also lead to muscle atrophy. However, the underlying mechanisms of muscle atrophy are not completely understood. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), play vital roles in muscle atrophy. This review mainly discusses the regulation of ncRNAs in muscle atrophy induced by various factors such as heart failure, cancer cachexia, aging, chronic obstructive pulmonary disease (COPD), peripheral nerve injury (PNI), chronic kidney disease (CKD), unhealthy habits, and usage of hormones; highlights the findings of ncRNAs as common regulators in multiple types of muscle atrophy; and summarizes current therapies and underlying mechanisms for muscle atrophy. This review will deepen the understanding of skeletal muscle biology and provide new strategies and insights into gene therapy for muscle atrophy.

Evaluation of selected IL6/STAT3 pathway molecules and miRNA expression in chronic obstructive pulmonary disease

COPD has been regarded as a global epidemic due to an increase in pollution and tobacco exposure. Therefore, the study of molecular mechanism as the basis for modern therapy is important. The aim of the study was the assessment of gene expression levels, IL-6, IL-6ST, PIAS3, STAT3, and miRNAs, miRNA-1, miRNA-106b, miRNA-155, in patients with COPD. Induced sputum as well as PBMC were collected from 40 patients clinically verified according to the GOLD 2021 (A-D) classification and from the control group (n = 20). The levels of gene and miRNA expression were analysed by qPCR. In induced sputum IL6 was significantly down-regulated in COPD group compared with control (p = 0.0008), while IL6ST were up-regulated (p = 0.05). The results were also statistically significant for STAT3 (p = 0.04) and miRNA-155 (p = 0.03) with higher expression in the current smokers compared to ex-smokers. Higher expression levels for IL6ST (p = 0.03) in COPD patients with the exacerbation history compared to COPD patients without the exacerbation history were noted. Compared induced sputum and PB lymphocytes we observed higher expression of IL6 (p = 0.0003), STAT3 (p = 0.000001) miRNA-106b (p = 0.000069 and miRNA-155 (p = 0.000016) in induced sputum with lower expression of PIAS3 (p = 0.006), IL6ST (p = 0.002) and miRNA-1 (p = 0.001). Differences in gene expression levels of the IL-6/IL6ST/STAT3 pathway and miRNA depending on the smoking status and classification of patients according to GOLD suggest the importance of these genes in the pathogenesis of COPD and may indicate their potential utility in monitoring the course of the disease.

Extracellular Vesicles in Airway Homeostasis and Pathophysiology

The epithelial–mesenchymal trophic unit (EMTU) is a morphofunctional entity involved in the maintenance of the homeostasis of airways as well as in the pathogenesis of several diseases, including asthma and chronic obstructive pulmonary disease (COPD). The “muco-microbiotic layer” (MML) is the innermost layer of airways made by microbiota elements (bacteria, viruses, archaea and fungi) and the surrounding mucous matrix. The MML homeostasis is also crucial for maintaining the healthy status of organs and its alteration is at the basis of airway disorders. Nanovesicles produced by EMTU and MML elements are probably the most important tool of communication among the different cell types, including inflammatory ones. How nanovesicles produced by EMTU and MML may affect the airway integrity, leading to the onset of asthma and COPD, as well as their putative use in therapy will be discussed here.

PI3K signalling in chronic obstructive pulmonary disease and opportunities for therapy

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease characterised by airway inflammation and progressive obstruction of the lung airflow. Current pharmacological treatments include bronchodilators, alone or in combination with steroids, or other anti-inflammatory agents, which have only partially contributed to the inhibition of disease progression and mortality. Therefore, further research unravelling the underlying mechanisms is necessary to develop new anti-COPD drugs with both lower toxicity and higher efficacy. Extrinsic signalling pathways play crucial roles in COPD development and exacerbations. In particular, phosphoinositide 3-kinase (PI3K) signalling has recently been shown to be a major driver of the COPD phenotype. Therefore, several small-molecule inhibitors have been identified to block the hyperactivation of this signalling pathway in COPD patients, many of them showing promising outcomes in both preclinical animal models of COPD and human clinical trials. In this review, we discuss the critically important roles played by hyperactivated PI3K signalling in the pathogenesis of COPD. We also critically review current therapeutics based on PI3K inhibition, and provide suggestions focusing on PI3K signalling for the further improvement of the COPD phenotype. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

MicroRNA-1: Diverse role of a small player in multiple cancers

The process of cancer initiation and development is a dynamic and complex mechanism involving multiple genetic and non-genetic variations. With the development of high throughput techniques like next-generation sequencing, the field of cancer biology extended beyond the protein-coding genes. It brought the functional role of noncoding RNAs into cancer-associated pathways. MicroRNAs (miRNAs) are one such class of noncoding RNAs regulating different cancer development aspects, including progression and metastasis. MicroRNA-1 (miR-1) is a highly conserved miRNA with a functional role in developing skeletal muscle precursor cells and cardiomyocytes and acts as a consistent tumor suppressor gene. In humans, two discrete genes, MIR-1-1 located on 20q13.333 and MIR-1-2 located on 18q11.2 loci encode for a single mature miR-1. Downregulation of miR-1 has been demonstrated in multiple cancers, including lung, breast, liver, prostate, colorectal, pancreatic, medulloblastoma, and gastric cancer. A vast number of studies have shown that miR-1 affects the hallmarks of cancer like proliferation, invasion and metastasis, apoptosis, angiogenesis, chemosensitization, and immune modulation. The potential therapeutic applications of miR-1 in multiple cancer pathways provide a novel platform for developing anticancer therapies. This review focuses on the different antitumorigenic and therapeutic aspects of miR-1, including how it regulates tumor development and associated immunomodulatory functions.

The Potential Roles of Exosomes in Chronic Obstructive Pulmonary Disease

Currently, chronic obstructive pulmonary disease (COPD) is one of the most common chronic lung diseases. Chronic obstructive pulmonary disease is characterized by progressive loss of lung function due to chronic inflammatory responses in the lungs caused by repeated exposure to harmful environmental stimuli. Chronic obstructive pulmonary disease is a persistent disease, with an estimated 384 million people worldwide living with COPD. It is listed as the third leading cause of death. Exosomes contain various components, such as lipids, microRNAs (miRNAs), long non-coding RNAs(lncRNAs), and proteins. They are essential mediators of intercellular communication and can regulate the biological properties of target cells. With the deepening of exosome research, it is found that exosomes are strictly related to the occurrence and development of COPD. Therefore, this review aims to highlight the unique role of immune-cell-derived exosomes in disease through complex interactions and their potentials as potential biomarkers new types of COPD.

MicroRNAs as Potential Regulators of Immune Response Networks in Asthma and Chronic Obstructive Pulmonary Disease

Chronic respiratory diseases (CRDs) are an important factor of morbidity and mortality, accounting for approximately 6% of total deaths worldwide. The main CRDs are asthma and chronic obstructive pulmonary disease (COPD). These complex diseases have different triggers including allergens, pollutants, tobacco smoke, and other risk factors. It is important to highlight that although CRDs are incurable, various forms of treatment improve shortness of breath and quality of life. The search for tools that can ensure accurate diagnosis and treatment is crucial. MicroRNAs (miRNAs) are small non-coding RNAs and have been described as promising diagnostic and therapeutic biomarkers for CRDs. They are implicated in multiple processes of asthma and COPD, regulating pathways associated with inflammation, thereby showing that miRNAs are critical regulators of the immune response. Indeed, miRNAs have been found to be deregulated in several biofluids (sputum, bronchoalveolar lavage, and serum) and in both structural lung and immune cells of patients in comparison to healthy subjects, showing their potential role as biomarkers. Also, miRNAs play a part in the development or termination of histopathological changes and comorbidities, revealing the complexity of miRNA regulation and opening up new treatment possibilities. Finally, miRNAs have been proposed as prognostic tools in response to both conventional and biologic treatments for asthma or COPD, and miRNA-based treatment has emerged as a potential approach for clinical intervention in these respiratory diseases; however, this field is still in development. The present review applies a systems biology approach to the understanding of miRNA regulatory networks in asthma and COPD, summarizing their roles in pathophysiology, diagnosis, and treatment.

Expression Analysis of Muscle-Specific miRNAs in Plasma-Derived Extracellular Vesicles from Patients with Chronic Obstructive Pulmonary Disease

MicroRNAs (miRNAs) are a class of short non-coding RNAs involved in the regulation of gene expression and the control of several cellular processes at physiological and pathological levels. Furthermore, extracellular vesicles (EV), which are small membrane-bound vesicles secreted by cells in the extracellular environment, contain functional miRNAs. The remarkable deregulation of many miRNAs has been demonstrated in respiratory diseases. Among them, miR-206, miR-133a-5p, and miR-133a-3p are striated muscle-specific miRNAs (myo-miRNA), related to skeletal muscle dysfunction, one of the commonest systemic manifestations in patients with chronic obstructive pulmonary disease (COPD). Nevertheless, their circulating expression in COPD patients is not demonstrated. For these reasons, we performed a pilot study to analyze the expression profiles of myo-miRNAs in plasma-derived EV from patients with COPD. We analyzed the expression profiles of selected myo-miRNAs in plasma-derived EV from COPD. Receiver operating characteristic analyses were carried out to evaluate whether selected plasma miRNAs were able to discriminate between different groups of COPD patients. We found EV-embedded myo-miRNAs in the bloodstream of COPD patients. Specifically, miR-206, miR-133a-5p and miR-133a-3p were significantly upregulated in group B patients. Receiver operating characteristic analyses of the combination of these selected miRNAs showed their high capacity to discriminate group B from other COPD patients. Our data provide evidence that myo-miRNA are present in EV in the plasma of COPD patients and their expression (miR-206, miR-133a-5p, and miR-133a-3p) can discriminate group B from group C patients. The future analysis of a larger number of patients should allow us to obtain more refined correlations.

MicroRNAs in chronic airway diseases: Clinical correlation and translational applications

MicroRNAs (miRNAs) are short single-stranded RNAs that have pivotal roles in disease pathophysiology through transcriptional and translational modulation of important genes. It has been implicated in the development of many diseases, such as stroke, cardiovascular conditions, cancers and inflammatory airway diseases. There is recent evidence that miRNAs play important roles in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD), and could help to distinguish between T2-low (non-eosinophilic, steroid-insensitive) versus T2-high (eosinophilic, steroid-sensitive) disease endotypes. As these are the two most prevalent chronic respiratory diseases globally, with rising disease burden, miRNA research might lead to the development of new diagnostic and therapeutic targets. Research involving miRNAs in airway disease is challenging because: (i) asthma and COPD are heterogeneous inflammatory airway diseases; there are overlapping but distinct inter- and intra-disease differences in the immunological pathophysiology, (ii) there exists more than 2000 known miRNAs and a single miRNA can regulate multiple targets, (iii) differential effects of miRNAs could be present in different cellular subtypes and tissues, and (iv) dysregulated miRNA expression might be a direct consequence of an indirect effect of airway disease onset or progression. As miRNAs are actively secreted in fluids and remain relatively stable, they have the potential for biomarker development and therapeutic targets. In this review, we summarize the preclinical data on potential miRNA biomarkers that mediate different pathophysiological mechanisms in airway disease. We discuss the framework for biomarker development using miRNA and highlight the need for careful patient characterization and endotyping in the screening and validation cohorts, profiling both airway and blood samples to determine the biological fluids of choice in different disease states or severity, and adopting an untargeted approach. Collaboration between the various stakeholders - pharmaceutical companies, laboratory professionals and clinician-scientists is crucial to reduce the difficulties and cost required to bring miRNA research into the translational stage for airway diseases.

miR-1-5p targets TGF-βR1 and is suppressed in the hypertrophying hearts of rats with pulmonary arterial hypertension

The microRNA miR-1 is an important regulator of muscle phenotype including cardiac muscle. Down-regulation of miR-1 has been shown to occur in left ventricular hypertrophy but its contribution to right ventricular hypertrophy in pulmonary arterial hypertension are not known. Previous studies have suggested that miR-1 may suppress transforming growth factor-beta (TGF-β) signalling, an important pro-hypertrophic pathway but only indirect mechanisms of regulation have been identified. We identified the TGF-β type 1 receptor (TGF-βR1) as a putative miR-1 target. We therefore hypothesized that miR-1 and TGF-βR1 expression would be inversely correlated in hypertrophying right ventricle of rats with pulmonary arterial hypertension and that miR-1 would inhibit TGF-β signalling by targeting TGF-βR1 expression. Quantification of miR-1 and TGF-βR1 in rats treated with monocrotaline to induce pulmonary arterial hypertension showed appropriate changes in miR-1 and TGF-βR1 expression in the hypertrophying right ventricle. A miR-1-mimic reduced enhanced green fluorescent protein expression from a reporter vector containing the TGF-βR1 3’- untranslated region and knocked down endogenous TGF-βR1. Lastly, miR-1 reduced TGF-β activation of a (mothers against decapentaplegic homolog) SMAD2/3-dependent reporter. Taken together, these data suggest that miR-1 targets TGF-βR1 and reduces TGF-β signalling, so a reduction in miR-1 expression may increase TGF-β signalling and contribute to cardiac hypertrophy.

Molecular techniques for respiratory diseases: MicroRNA and extracellular vesicles

miRNA are a class of evolutionarily conserved non-coding 19- to 22-nt regulatory RNA. They affect various cellular functions through modulating the transcriptional and post-transcriptional levels of their target mRNA by changing the stability of protein-coding transcripts or attenuating protein translation. miRNA were discovered in the early 1990s, and they have been the focus of new research in both basic and clinical medical sciences. Today, it has become clear that specific miRNA are linked to the pathogenesis of respiratory diseases, as well as cancer and cardiovascular disease. In addition, EV, including exosomes, which are small membrane-bound vesicles secreted by cells, were found to contain various functional miRNA that can be used for diagnostic and therapeutic purposes. As body fluids, such as blood and respiratory secretions, are major miRNA sources in the body, EV carrying extracellular miRNA are considered potentially useful for the diagnosis and assessment of pathological conditions, as well as the treatment of respiratory or other diseases. Although research in the field of lung cancer is actively progressing, studies in other respiratory fields have emerged recently as well. In this review, we provide an update in the topics of miRNA and EV focused on airway inflammatory diseases, such as asthma and COPD, and explore their potential for clinical applications on respiratory diseases.

Clinical value of non-coding RNAs in cardiovascular, pulmonary, and muscle diseases

Although a majority of the mammalian genome is transcribed to RNA, mounting evidence indicates that only a minor proportion of these transcriptional products are actually translated into proteins. Since the discovery of the first non-coding RNA (ncRNA) in the 1980s, the field has gone on to recognize ncRNAs as important molecular regulators of RNA activity and protein function, knowledge of which has stimulated the expansion of a scientific field that quests to understand the role of ncRNAs in cellular physiology, tissue homeostasis, and human disease. Although our knowledge of these molecules has significantly improved over the years, we have limited understanding of their precise functions, protein interacting partners, and tissue-specific activities. Adding to this complexity, it remains unknown exactly how many ncRNAs there are in existence. The increased use of high-throughput transcriptomics techniques has rapidly expanded the list of ncRNAs, which now includes classical ncRNAs (e.g., ribosomal RNAs and transfer RNAs), microRNAs, and long ncRNAs. In addition, splicing by-products of protein-coding genes and ncRNAs, so-called circular RNAs, are now being investigated. Because there is substantial heterogeneity in the functions of ncRNAs, we have summarized the present state of knowledge regarding the functions of ncRNAs in heart, lungs, and skeletal muscle. This review highlights the pathophysiologic relevance of these ncRNAs in the context of human cardiovascular, pulmonary, and muscle diseases.

Repetitive vascular occlusion stimulus (RVOS) versus standard care to prevent muscle wasting in critically ill patients (ROSProx):a study protocol for a pilot randomised controlled trial

BACKGROUND

Forty per cent of critically ill patients are affected by intensive care unit-acquired weakness (ICU-AW), to which skeletal muscle wasting makes a substantial contribution. This can impair outcomes in hospital, and can cause long-term physical disability after hospital discharge. No effective mitigating strategies have yet been identified. Application of a repetitive vascular occlusion stimulus (RVOS) a limb pressure cuff inducing brief repeated cycles of ischaemia and reperfusion, can limit disuse muscle atrophy in both healthy controls and bed-bound patients recovering from knee surgery. We wish to determine whether RVOS might be effective in mitigating against muscle wasting in the ICU. Given that RVOS can also improve vascular function in healthy controls, we also wish to assess such effects in the critically ill. We here describe a pilot study to assess whether RVOS application is safe, tolerable, feasible and acceptable for ICU patients.

METHODS

This is a randomised interventional feasibility trial. Thirty-two ventilated adult ICU patients with multiorgan failure will be recruited within 48 h of admission and randomised to either the intervention arm or the control arm. Intervention participants will receive RVOS twice daily (except only once on day 1) for up to 10 days or until ICU discharge. Serious adverse events and tolerability (pain score) will be recorded; feasibility of trial procedures will be assessed against pre-specified criteria and acceptability by semi-structured interview. Together with vascular function, muscle mass and quality will be assessed using ultrasound and measures of physical function at baseline, on days 6 and 11 of study enrolment, and at ICU and hospital discharge. Blood and urine biomarkers of muscle metabolism, vascular function, inflammation and DNA damage/repair mechanism will also be analysed. The Health questionnaire will be completed 3 months after hospital discharge.

DISCUSSION

If this study demonstrates feasibility, the derived data will be used to inform the design (and sample size) of an appropriately-powered prospective trial to clarify whether RVOS can help preserve muscle mass/improve vascular function in critically ill patients.

TRIAL REGISTRATION

ISRCTN Registry, ISRCTN44340629. Registered on 26 October 2017.

Evaluation of Serum Paired MicroRNA Ratios for Differential Diagnosis of Non-Small Cell Lung Cancer and Benign Pulmonary Diseases

BACKGROUND AND OBJECTIVE

To clarify whether there are different expressions between lung cancer and benign pulmonary diseases, we studied seven microRNAs (miRNAs) in serum from patients with non-small cell lung cancer (NSCLC), benign pulmonary nodules and four pulmonary inflammation diseases.

METHODS

We detected the expression of miRNAs using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR).

RESULTS

We found that five miRNA ratios-miR-15b-5p/miR-146b-3p, miR-20a-5p/miR-146b-3p, miR-19a-3p/miR-146b-3p, miR-92a-3p/miR-146b-3p, and miR-16-5p/miR-146b-3p-show higher expression in the NSCLC group than the benign pulmonary nodule group, and 13 ratios of miRNAs were significantly upregulated in the NSCLC group compared with the pulmonary inflammation diseases group. Receiver operating characteristic (ROC) curve analysis was performed. For NSCLC and benign pulmonary nodules, the sensitivity and specificity were 0.70 and 0.90, respectively. For NSCLC and pulmonary inflammation diseases, the sensitivity and specificity were 0.81 and 0.71, respectively.

CONCLUSION

The ratios of miRNAs can be used as potential non-invasive biomarkers for diagnosis of early-stage NSCLC and benign pulmonary diseases.

Quadriceps miR-542-3p and -5p are elevated in COPD and reduce function by inhibiting ribosomal and protein synthesis

Reduced physical performance reduces quality of life in patients with chronic obstructive pulmonary disease (COPD). Impaired physical performance is, in part, a consequence of reduced muscle mass and function, which is accompanied by mitochondrial dysfunction. We recently showed that miR-542-3p and miR-542-5p were elevated in a small cohort of COPD patients and more markedly in critical care patients. In mice, these microRNAs (miRNAs) promoted mitochondrial dysfunction suggesting that they would affect physical performance in patients with COPD, but we did not explore the association of these miRNAs with disease severity or physical performance further. We therefore quantified miR-542-3p/5p and mitochondrial rRNA expression in RNA extracted from quadriceps muscle of patients with COPD and determined their association with physical performance. As miR-542-3p inhibits ribosomal protein synthesis its ability to inhibit protein synthesis was also determined in vitro. Both miR-542-3p expression and -5p expression were elevated in patients with COPD (5-fold P < 0.001) and the degree of elevation associated with impaired lung function (transfer capacity of the lung for CO in % and forced expiratory volume in 1 s in %) and physical performance (6-min walk distance in %). In COPD patients, the ratio of 12S rRNA to 16S rRNA was suppressed suggesting mitochondrial ribosomal stress and mitochondrial dysfunction and miR-542-3p/5p expression was inversely associated with mitochondrial gene expression and positively associated with p53 activity. miR-542-3p suppressed RPS23 expression and maximal protein synthesis in vitro. Our data show that miR-542-3p and -5p expression is elevated in COPD patients and may suppress physical performance at least in part by inhibiting mitochondrial and cytoplasmic ribosome synthesis and suppressing protein synthesis. NEW & NOTEWORTHY miR-542-3p and -5p are elevated in the quadriceps muscle of patients with chronic obstructive pulmonary disease (COPD) in proportion to the severity of their lung disease. These microRNAs inhibit mitochondrial and cytoplasmic protein synthesis suggesting that they contribute to impaired exercise performance in COPD.

Muscle wasting in the presence of disease, why is it so variable?

Skeletal muscle wasting is a common clinical feature of many chronic diseases and also occurs in response to single acute events. The accompanying loss of strength can lead to significant disability, increased care needs and have profound negative effects on quality of life. As muscle is the most abundant source of amino acids in the body, it appears to function as a buffer for fuel and substrates that can be used to repair damage elsewhere and to feed the immune system. In essence, the fundamentals of muscle wasting are simple: less muscle is made than is broken down. However, although well-described mechanisms modulate muscle protein turnover, significant individual differences in the amount of muscle lost in the presence of a given severity of disease complicate the understanding of underlying mechanisms and suggest that individuals have different sensitivities to signals for muscle loss. Furthermore, the rate at which muscle protein is turned over under normal conditions means that clinically significant muscle loss can occur with changes in the rate of protein synthesis and/or breakdown that are too small to be measurable. Consequently, the changes in expression of factors regulating muscle turnover required to cause a decline in muscle mass are small and, except in cases of rapid wasting, there is no consistent pattern of change in the expression of factors that regulate muscle mass. MicroRNAs are fine tuners of cell phenotype and are therefore ideally suited to cause the subtle changes in proteome required to tilt the balance between synthesis and degradation in a way that causes clinically significant wasting. Herein we present a model in which muscle loss as a consequence of disease in non-muscle tissue is modulated by a set of microRNAs, the muscle expression of which is associated with severity of disease in the non-muscle tissue. These microRNAs alter fundamental biological processes including the synthesis of ribosomes and mitochondria leading to reduced protein synthesis and increased protein breakdown, thereby freeing amino acids from the muscle. We argue that the variability in muscle loss observed in the human population arises from at least two sources. The first is from pre-existing or disease-induced variation in the expression of microRNAs controlling the sensitivity of muscle to the atrophic signal and the second is from the expression of microRNAs from imprinted loci (i.e. only expressed from the maternally or paternally inherited allele) and may control the rate of myonuclear recruitment. In the absence of disease, these factors do not correlate with muscle mass, since there is no challenge to the established balance. However, in the presence of such a challenge, these microRNAs determine the rate of decline for a given disease severity. Together these mechanisms provide novel insight into the loss of muscle mass and its variation in the human population. The involvement of imprinted loci also suggests that genes that regulate early development also contribute to the ability of individuals to resist muscle loss in response to disease.

The roles of microRNAs in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive and irreversible airflow obstruction, with an abnormal lung function. The etiology of COPD correlates with complex interactions between environmental and genetic determinants. However, the exact pathogenesis of COPD is obscure although it involves multiple aspects including oxidative stress, imbalance between proteolytic and anti-proteolytic activity, immunity and inflammation, apoptosis, and repair and destruction in both airways and lungs. Many genes have been demonstrated to be involved in those pathogenic processes of this disease in patients exposed to harmful environmental factors. Previous reports have investigated promising microRNAs (miRNAs) to disclose the molecular mechanisms for COPD development induced by different environmental exposure and genetic predisposition encounter, and find some potential miRNA biomarkers for early diagnosis and treatment targets of COPD. In this review, we summarized the expression profiles of the reported miRNAs from studies of COPD associated with environmental risk factors including cigarette smoking and air pollution exposures, and provided an overview of roles of those miRNAs in the pathogenesis of the disease. We also highlighted the potential utility and limitations of miRNAs serving as diagnostic biomarkers and therapeutic targets for COPD.

Differences in micro-RNA expression profile between vastus lateralis samples and myotubes in COPD cachexia

Quadriceps muscle weakness and wasting are common comorbidities in chronic obstructive pulmonary disease (COPD). Micro-RNA expression upregulation may favor muscle mass growth and differentiation. We hypothesized that the profile of muscle-enriched micro-RNAs in cultured myotubes differs between patients with COPD of a wide range of body composition and healthy controls and that expression levels of those micro-RNAs from patients with COPD and controls differ between in vivo and in vitro conditions. Twenty-nine patients with COPD [ n = 15 with muscle wasting and fat-free mass index (FFMI) 15 kg/m² and n = 14 with normal body composition and FFMI 18 kg/m²] and 10 healthy controls (FFMI 19 kg/m²) were consecutively recruited. Biopsies from the vastus lateralis muscle were obtained in all study subjects. A fragment of each biopsy was used to obtain primary cultures, in which muscle cells were first proliferated to be then differentiated into actual myotubes. In both sets of experiments (in vivo biopsies and in vitro myotubes) the following muscle-enriched micro-RNAs from all the study subjects were analyzed using quantitative real-time PCR amplification: micro-RNA (miR)-1, miR-133a, miR-206, miR-486, miR-29b, miR-27a, and miR-181a. Whereas the expression of miR-1, miR-206, miR-486, and miR-29b was upregulated in the muscle biopsies of patients with COPD compared with those of healthy controls, levels of none of the studied micro-RNAs in the myotubes (primary cultured cells) significantly differed between patients with COPD and the controls. We conclude from these findings that environmental factors (blood flow, muscle metabolism, and inflammation) taking place in vivo (biopsies) in muscles may account for the differences observed in micro-RNA expression between patients with COPD and controls. In the myotubes, however, the expression of the same micro-RNAs did not differ between the study subjects as such environmental factors were not present. These findings suggest that therapeutic strategies should rather target environmental factors in COPD muscle wasting as the profile of micro-RNA expression in myotubes was similar in patients to that observed in the healthy controls. NEW & NOTEWORTHY Environmental factors taking place in vivo (biopsies) in the muscles may explain differences observed in micro-RNA expression between patients with chronic obstructive pulmonary disease (COPD) and controls. In the myotubes, however, the expression of the same micro-RNAs did not differ between the study subjects as such environmental factors were not present. These findings suggest that therapeutic strategies should rather target environmental factors in COPD muscle wasting and cachexia as micro-RNA expression profile in myotubes was similar between patients and controls.

Skeletal Muscle Fiber Type in Hypoxia: Adaptation to High-Altitude Exposure and Under Conditions of Pathological Hypoxia

Skeletal muscle is able to modify its size, and its metabolic/contractile properties in response to a variety of stimuli, such as mechanical stress, neuronal activity, metabolic and hormonal influences, and environmental factors. A reduced oxygen availability, called hypoxia, has been proposed to induce metabolic adaptations and loss of mass in skeletal muscle. In addition, several evidences indicate that muscle fiber-type composition could be affected by hypoxia. The main purpose of this review is to explore the adaptation of skeletal muscle fiber-type composition to exposure to high altitude (ambient hypoxia) and under conditions of pathological hypoxia, including chronic obstructive pulmonary disease (COPD), chronic heart failure (CHF) and obstructive sleep apnea syndrome (OSAS). The muscle fiber-type composition of both adult animals and humans is not markedly altered during chronic exposure to high altitude. However, the fast-to-slow fiber-type transition observed in hind limb muscles during post-natal development is impaired in growing rats exposed to severe altitude. A slow-to-fast transition in fiber type is commonly found in lower limb muscles from patients with COPD and CHF, whereas a transition toward a slower fiber-type profile is often found in the diaphragm muscle in these two pathologies. A slow-to-fast transformation in fiber type is generally observed in the upper airway muscles in rodent models of OSAS. The factors potentially responsible for the adaptation of fiber type under these hypoxic conditions are also discussed in this review. The impaired locomotor activity most likely explains the changes in fiber type composition in growing rats exposed to severe altitude. Furthermore, chronic inactivity and muscle deconditioning could result in the slow-to-fast fiber-type conversion in lower limb muscles during COPD and CHF, while the factors responsible for the adaptation of muscle fiber type during OSAS remain hypothetical. Finally, the role played by cellular hypoxia, hypoxia-inducible factor-1 alpha (HIF-1α), and other molecular regulators in the adaptation of muscle fiber-type composition is described in response to high altitude exposure and conditions of pathological hypoxia.

Epigenetic changes due to physical activity

One of the epigenetic-modifying factors is regular and continuous physical activity. This article attempts to investigate the effects of physical activity and exercise on changes in histone proteins and gene expression, as well as the effect of these exercises on the prevention of certain cancers and the ejection of age-related illnesses and cellular oxidation interactions. All of this is due to epigenetic changes and gene expression. Most studies have reported the positive effects of regular exercises on the expression of histone proteins. DNA methylation and the prevention of certain diseases such as cancer and respiratory diseases, caused by antioxidative interactions that occur more often in the elderly, have been studied.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

Non-coding RNAs and exercise: pathophysiological role and clinical application in the cardiovascular system

There is overwhelming evidence that regular exercise training is protective against cardiovascular disease (CVD), the main cause of death worldwide. Despite the benefits of exercise, the intricacies of their underlying molecular mechanisms remain largely unknown. Non-coding RNAs (ncRNAs) have been recognized as a major regulatory network governing gene expression in several physiological processes and appeared as pivotal modulators in a myriad of cardiovascular processes under physiological and pathological conditions. However, little is known about ncRNA expression and role in response to exercise. Revealing the molecular components and mechanisms of the link between exercise and health outcomes will catalyse discoveries of new biomarkers and therapeutic targets. Here we review the current understanding of the ncRNA role in exercise-induced adaptations focused on the cardiovascular system and address their potential role in clinical applications for CVD. Finally, considerations and perspectives for future studies will be proposed.

The role of microRNA-1 targeting of MAPK3 in myocardial ischemia-reperfusion injury in rats undergoing sevoflurane preconditioning via the PI3K/Akt pathway

Recent studies have uncovered the vital roles played by microRNAs in regulating cardiac injury. Among them, the cardiac enriched microRNA-1 (miR-1) has been extensively studied and proven to be detrimental to cardiac myocytes. Hence, the current study aimed to explore whether miR-1 affects myocardial ischemia-reperfusion injury (MIRI) in rats undergoing sevoflurane preconditioning and the underlying mechanism. After successful model establishment, rats with MIRI were transfected with mimics or inhibitors of miR-1, or siRNA against MAPK3, and then were injected with sevoflurane. A luciferase reporter gene assay was conducted to evaluate the targeting relationship between miR-1 and MAPK3. Reverse transcription quantitative polymerase chain reaction and Western blot analysis were employed to evaluate the expressions of miR-1, MAPK3, phosphatidylinositol 3-kinase (PI3K), and Akt. Additionally, the concentration of lactate dehydrogenase (LDH) was determined. Cell apoptosis and viability were assessed using TUNEL and cell counting kit-8 assays, and the ischemic area at risk and infarct size were detected using Evans blue and triphenyltetrazolium chloride staining. MAPK3 was found to be the target gene of miR-1. miR-1 expressed at a high level whereas MAPK3 expressed at a low level in MIRI rats. Overexpressing miR-1 or silencing MAPK3 blocked the PI3K/Akt pathway to increase cell apoptosis, ischemic area at risk, and infarct area but decreased cell viability and increased LDH concentration. In contrast, miR-1 downregulation abrogated the effects induced by miR-1 mimics or siRNA against MAPK3. These findings indicate that inhibition of miR-1 promotes MAPK3 to protect against MIRI in rats undergoing sevoflurane preconditioning through activation of the PI3K/Akt pathway.

Differential expression of microRNAs and other small RNAs in muscle tissue of patients with ALS and healthy age-matched controls

Amyotrophic lateral sclerosis is a late-onset disorder primarily affecting motor neurons and leading to progressive and lethal skeletal muscle atrophy. Small RNAs, including microRNAs (miRNAs), can serve as important regulators of gene expression and can act both globally and in a tissue-/cell-type-specific manner. In muscle, miRNAs called myomiRs govern important processes and are deregulated in various disorders. Several myomiRs have shown promise for therapeutic use in cellular and animal models of ALS; however, the exact miRNA species differentially expressed in muscle tissue of ALS patients remain unknown. Following small RNA-Seq, we compared the expression of small RNAs in muscle tissue of ALS patients and healthy age-matched controls. The identified snoRNAs, mtRNAs and other small RNAs provide possible molecular links between insulin signaling and ALS. Furthermore, the identified miRNAs are predicted to target proteins that are involved in both normal processes and various muscle disorders and indicate muscle tissue is undergoing active reinnervation/compensatory attempts thus providing targets for further research and therapy development in ALS.

miR-424-5p reduces ribosomal RNA and protein synthesis in muscle wasting

BACKGROUND

A loss of muscle mass occurs as a consequence of a range of chronic and acute diseases as well as in older age. This wasting results from an imbalance of protein synthesis and degradation with a reduction in synthesis and resistance to anabolic stimulation often reported features. Ribosomes are required for protein synthesis, so changes in the control of ribosome synthesis are potential contributors to muscle wasting. MicroRNAs (miRNAs) are known regulators of muscle phenotype and have been shown to modulate components of the protein synthetic pathway. One miRNA that is predicted to target a number of components of protein synthetic pathway is miR-424-5p, which is elevated in the quadriceps of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Targets of miR-424-5p were identified by Argonaute2 pull down, and the effects of the miRNA on RNA and protein expression were determined by quantitative polymerase chain reaction and western blotting in muscle cells in vitro. Protein synthesis was determined by puromycin incorporation in vitro. The miRNA was over-expressed in the tibialis anterior muscle of mice by electroporation and the effects quantified. Finally, quadriceps expression of the miRNA was determined by quantitative polymerase chain reaction in patients with COPD and intensive care unit (ICU)-acquired weakness and in patients undergoing aortic surgery as well as in individuals from the Hertfordshire Sarcopenia Study.

RESULTS

Pull-down assays showed that miR-424-5p bound to messenger RNAs encoding proteins associated with muscle protein synthesis. The most highly enriched messenger RNAs encoded proteins required for the Pol I RNA pre-initiation complex required for ribosomal RNA (rRNA) transcription, (PolR1A and upstream binding transcription factor). In vitro, miR-424-5p reduced the expression of these RNAs, reduced rRNA levels, and inhibited protein synthesis. In mice, over-expression of miR-322 (rodent miR-424 orthologue) caused fibre atrophy and reduced upstream binding transcription factor expression and rRNA levels. In humans, elevated miR-424-5p associated with markers of disease severity in COPD (FEV₁ %), in patients undergoing aortic surgery (LVEF%), and in patients with ICU-acquired weakness (days in ICU). In patients undergoing aortic surgery, preoperative miR-424-5p expression in skeletal muscle was associated with muscle loss over the following 7 days.

CONCLUSIONS

These data suggest that miR-424-5p regulates rRNA synthesis by inhibiting Pol I pre-initiation complex formation. Increased miR-424-5p expression in patients with conditions associated with muscle wasting is likely to contribute to the inhibition of protein synthesis and loss of muscle mass.

Chronic obstructive pulmonary disease: MicroRNAs and exosomes as new diagnostic and therapeutic biomarkers

Chronic obstructive pulmonary disease (COPD) is known as a progressive lung disease and the fourth leading cause of death worldwide. Despite valuable efforts, there is still no accurate diagnostic and prognostic tool for COPD. Hence, it seems that finding new biomarkers could contribute to provide better therapeutic platforms for COPD patients. Among various biomarkers, microRNAs (miRNAs) have emerged as new biomarkers for the prognosis and diagnosis of patients with COPD. It has been shown that deregulation of miRNAs targeting a variety of cellular and molecular pathways such as Notch, Wnt, hypoxia-inducible factor-1α, transforming growth factor, Kras, and Smad could be involved in COPD pathogenesis. Multiple lines of evidence have indicated that extracellular vesicles such as exosomes could carry a variety of cargos (i.e., mRNAs, miRNAs, and proteins) which transfer various cellular and molecular signals to recipient cells. Here, we summarized various miRNAs which could be applied as diagnostic and prognostic biomarkers in the treatment of patients with COPD. Moreover, we highlighted the role of extracellular vesicles containing miRNAs as diagnostic and prognostic biomarkers in COPD patients.

MicroRNAs, Long Noncoding RNAs, and Their Functions in Human Disease

Majority of the human genome is transcribed into RNAs with absent or limited protein-coding potential. microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are two major families of the non-protein-coding transcripts. miRNAs and lncRNAs can regulate fundamental cellular processes via diverse mechanisms. The expression and function of miRNAs and lncRNAs are tightly regulated in development and physiological homeostasis. Dysregulation of miRNAs and lncRNAs is critical to pathogenesis of human disease. Moreover, recent evidence indicates a cross talk between miRNAs and lncRNAs. Herein we review recent advances in the biology of miRNAs and lncRNAs with respect to the above aspects. We focus on their roles in cancer, respiratory disease, and neurodegenerative disease. The complexity, flexibility, and versatility of the structures and functions of miRNAs and lncRNAs demand integration of experimental and bioinformatics tools to acquire sufficient knowledge for applications of these noncoding RNAs in clinical care.

miR-422a suppresses SMAD4 protein expression and promotes resistance to muscle loss

BACKGROUND

Loss of muscle mass and strength are important sequelae of chronic disease, but the response of individuals is remarkably variable, suggesting important genetic and epigenetic modulators of muscle homeostasis. Such factors are likely to modify the activity of pathways that regulate wasting, but to date, few such factors have been identified.

METHODS

The effect of miR-422a on SMAD4 expression and transforming growth factor (TGF)-β signalling were determined by western blotting and luciferase assay. miRNA expression was determined by qPCR in plasma and muscle biopsy samples from a cross-sectional study of patients with chronic obstructive pulmonary disease (COPD) and a longitudinal study of patients undergoing aortic surgery, who were subsequently admitted to the intensive care unit (ICU).

RESULTS

miR-422a was identified, by a screen, as a microRNA that was present in the plasma of patients with COPD and negatively associated with muscle strength as well as being readily detectable in the muscle of patients. In vitro, miR-422a suppressed SMAD4 expression and inhibited TGF-beta and bone morphogenetic protein-dependent luciferase activity in muscle cells. In male patients with COPD and those undergoing aortic surgery and on the ICU, a model of ICU-associated muscle weakness, quadriceps expression of miR-422a was positively associated with muscle strength (maximal voluntary contraction r = 0.59, P < 0.001 and r = 0.51, P = 0.004, for COPD and aortic surgery, respectively). Furthermore, pre-surgery levels of miR-422a were inversely associated with the amount of muscle that would be lost in the first post-operative week (r = -0.57, P < 0.001).

CONCLUSIONS

These data suggest that differences in miR-422a expression contribute to the susceptibility to muscle wasting associated with chronic and acute disease and that at least part of this activity may be mediated by reduced TGF-beta signalling in skeletal muscle.

miR-322-5p targets IGF-1 and is suppressed in the heart of rats with pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterised by remodelling of the pulmonary vasculature leading to right ventricular hypertrophy. Here, we show that miR‐322‐5p (the rodent orthologue of miR‐424‐5p) expression is decreased in the right ventricle of monocrotaline‐treated rats, a model of PAH, whereas a putative target insulin‐like growth factor 1 (IGF‐1) is increased. IGF‐1 mRNA was enriched 16‐fold in RNA immunoprecipitated with Ago2, indicating binding to miR‐322‐5p. In cell transfection experiments, miR‐322‐5p suppressed the activity of a luciferase reporter containing a section of the IGF‐1 3′ untranslated region (UTR) as well as IGF‐1 mRNA and protein levels. Taken together, these data suggest that miR‐322 targets IGF‐1, a process downregulated in PAH‐related RV hypertrophy.

Noncoding RNAs in Muscle Atrophy

Denervation, disuse, fasting, and various diseases could induce skeletal muscle atrophy, which results in the decline of life quality and increase of the mortality risk for patients. Noncoding RNAs (ncRNAs) are implicated important in regulating gene expression. Thus, ncRNAs, especially microRNAs and long noncoding RNAs (lncRNAs), have gained widespread attention as crucial players in numerous physiological and pathological processes, including skeletal muscle atrophy. In this review, we comprehensively described the potential of circulating microRNAs as biomarkers, summarized the profiling of microRNAs and lncRNAs in atrophying muscles, as well as discussed the effects and underlying mechanisms of microRNA machinery proteins, microRNAs, and lncRNAs in skeletal muscle atrophy. Considering the large quantity and variety of ncRNAs, the understanding of ncRNAs in muscle atrophy is still very limited. Future studies are needed to elucidate the possibility of ncRNAs as diagnosis biomarkers and therapeutic targets in muscle atrophy.

MicroRNA-542 Promotes Mitochondrial Dysfunction and SMAD Activity and Is Elevated in Intensive Care Unit-acquired Weakness

RATIONALE

Loss of skeletal muscle mass and function is a common consequence of critical illness and a range of chronic diseases, but the mechanisms by which this occurs are unclear.

OBJECTIVES

To identify microRNAs (miRNAs) that were increased in the quadriceps of patients with muscle wasting and to determine the molecular pathways by which they contributed to muscle dysfunction.

METHODS

miRNA-542-3p/5p (miR-542-3p/5p) were quantified in the quadriceps of patients with chronic obstructive pulmonary disease and intensive care unit-acquired weakness (ICUAW). The effect of miR-542-3p/5p was determined on mitochondrial function and transforming growth factor-β signaling in vitro and in vivo.

MEASUREMENTS AND MAIN RESULTS

miR-542-3p/5p were elevated in patients with chronic obstructive pulmonary disease but more markedly in patients with ICUAW. In vitro, miR-542-3p suppressed the expression of the mitochondrial ribosomal protein MRPS10 and reduced 12S ribosomal RNA (rRNA) expression, suggesting mitochondrial ribosomal stress. miR-542-5p increased nuclear phospho-SMAD2/3 and suppressed expression of SMAD7, SMURF1, and PPP2CA, proteins that inhibit or reduce SMAD2/3 phosphorylation, suggesting that miR-542-5p increased transforming growth factor-β signaling. In mice, miR-542 overexpression caused muscle wasting, and reduced mitochondrial function, 12S rRNA expression, and SMAD7 expression, consistent with the effects of the miRNAs in vitro. Similarly, in patients with ICUAW, the expression of 12S rRNA and of the inhibitors of SMAD2/3 phosphorylation were reduced, indicative of mitochondrial ribosomal stress and increased transforming growth factor-β signaling. In patients undergoing aortic surgery, preoperative levels of miR-542-3p/5p were positively correlated with muscle loss after surgery.

CONCLUSIONS

Elevated miR-542-3p/5p may cause muscle atrophy in intensive care unit patients through the promotion of mitochondrial dysfunction and activation of SMAD2/3 phosphorylation.

Posttranscriptional control of airway inflammation

Acute inflammation in the lungs is a vital protective response, efficiently and swiftly eliminating inciters of tissue injury. However, in respiratory diseases characterized by chronic inflammation, such as chronic obstructive pulmonary disease and asthma, enhanced expression of inflammatory mediators leads to tissue damage and impaired lung function. Although transcription is an essential first step in the induction of proinflammatory genes, tight regulation of inflammation requires more rapid, flexible responses. Increasing evidence shows that such responses are achieved by posttranscriptional mechanisms directly affecting mRNA stability and translation initiation. RNA-binding proteins, microRNAs, and long noncoding RNAs interact with messenger RNA and each other to impact the stability and/or translation of mRNAs implicated in lung inflammation. Recent research has shown that these biological processes play a central role in the pathogenesis of several important pulmonary conditions. This review will highlight several posttranscriptional control mechanisms that influence lung inflammation and the known associations of derangements in these mechanisms with common respiratory diseases. WIREs RNA 2018, 9:e1455. doi: 10.1002/wrna.1455 This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Turnover and Surveillance > Regulation of RNA Stability.

Increased Myogenic and Protein Turnover Signaling in Skeletal Muscle of Chronic Obstructive Pulmonary Disease Patients With Sarcopenia

BACKGROUND

Sarcopenia was recently recognized as an independent condition by an International Classification of Diseases, Tenth Revision, Clinical Modification code, and is a frequently observed comorbidity in chronic obstructive pulmonary disease (COPD). Muscle mass is primarily dictated by the balance between protein degradation and synthesis, but their relative contribution to sarcopenia is unclear.

OBJECTIVE

We aimed to assess potential differential molecular regulation of protein degradation and synthesis, as well as myogenesis, in the skeletal muscle of COPD patients with and without sarcopenia.

METHODS

Muscle biopsies were obtained from the vastus lateralis muscle. Patients with COPD were clustered based on sarcopenia defined by low appendicular skeletal muscle mass index (nonsarcopenic COPD, n = 53; sarcopenic COPD, n = 39), and compared with healthy nonsarcopenic controls (n = 13). The mRNA and protein expression of regulators and mediators of ubiquitin-proteasome system (UPS), autophagy-lysosome system (autophagy), and protein synthesis were analyzed. Furthermore, mRNA expression of myogenesis markers was assessed.

RESULTS

UPS signaling was unaltered, whereas indices of UPS regulation (eg, FOXO1 protein; p-FOXO3/FOXO3), autophagy signaling (eg, LC3BII/I; p-ULK1[Ser757]/ULK1), and protein synthesis signaling (eg, AKT1; p-GSK3B/GSK3B; p-4E-BP1/4E-BP1) were increased in COPD. These alterations were even more pronounced in COPD patients with sarcopenia (eg, FOXO1 protein; p-FOXO1/FOXO1; LC3BII/I; p-ULK(Ser555); p-AKT1/AKT1; AKT1; p-4E-BP1). Furthermore, myogenic signaling (eg, MYOG) was increased in COPD despite a concomitant increase of myostatin (MSTN) mRNA expression, with no difference between sarcopenic and nonsarcopenic COPD patients.

CONCLUSION

Together with elevated myogenic signaling, the increase in muscle protein turnover signaling in COPD, which is even more prominent in COPD patients with sarcopenia, reflects molecular alterations associated with muscle repair and remodeling.

Genetic polymorphism and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common chronic disease, and its morbidity and mortality are increasing. There are many studies that have tried to explain the pathogenesis of COPD from genetic susceptibility, to identify the susceptibility of COPD factors, which play a role in early prevention, early detection and the early treatment. However, it is well known that COPD is an inflammatory disease characterized by incomplete reversible airflow limitation in which genes interact with the environment. In recent years, many studies have proved gene polymorphisms and COPD correlation. However, there is less research on the relationship between COPD and genome-wide association study (GWAS), epigenetics and apoptosis. In this paper, we summarized the correlation between gene level and COPD from the following four aspects: the GWAS, the gene polymorphism, the epigenetics and the apoptosis, and the relationship between COPD and gene is summarized comprehensively.

miR-206 inhibits FN1 expression and proliferation and promotes apoptosis of rat type II alveolar epithelial cells

Bronchopulmonary dysplasia (BPD) is a syndrome of respiratory distress caused by chronic lung injury, primarily in preterm infants. miR-206 and fibronectin 1 (FN1) are associated with the development of BPD. The present study used rat type II alveolar epithelial cells (AECII) to investigate the underlying mechanisms of BPD. AECII were isolated using a primary cell culture prior to alkaline phosphatase staining and immunofluorescence of surfactant protein C (SP-C). These were used to verify the presence of AECII. AECII were then divided into four groups, which were transfected with four different plasmids. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to determine the relative expression of miR-206 in the each group. The gene and protein expression level of FN1 was detected by RT-qPCR and immunofluorescence. The proliferation of AECII in each of the four groups was evaluated using an MTT assay 48 h following transfection. The percentage of apoptotic cells was determined by flow cytometric analysis. The present study demonstrated that upregulation of miR-206 decreased the expression of FN1 (P<0.05) and low levels of miR-206 led to increased expression of FN1 (P<0.05) in AECII. Furthermore, the forced expression of miR-206 suppressed proliferation and promoted apoptosis of AECII while downregulation of miR-206 had the opposite effect (P<0.05). The results of the current study provide valuable insights into the prevention of BPD and suggest that miR-206 may be used as a potential molecular target for BPD therapy in the future.

Reduced nuclear translocation of serum response factor is associated with skeletal muscle atrophy in a cigarette smoke-induced mouse model of COPD

Skeletal muscle atrophy and dysfunction are common complications in the chronic obstructive pulmonary disease (COPD). However, the underlying molecular mechanism remains elusive. Serum response factor (SRF) is a transcription factor which is critical in myocyte differentiation and growth. In this study, we established a mouse COPD model induced by cigarette smoking (CS) exposure for 24 weeks, with apparent pathophysiological changes, including increased airway resistance, enlarged alveoli, and skeletal muscle atrophy. Levels of upstream regulators of SRF, striated muscle activator of Rho signaling (STARS), and ras homolog gene family, member A (RhoA) were decreased in quadriceps muscle of COPD mice. Meanwhile, the nucleic location of SRF was diminished along with its cytoplasmic accumulation. There was a downregulation of the target muscle-specific gene, Igf1. These results suggest that the CS is one of the major causes for COPD pathogenesis, which induces the COPD-associated skeletal muscle atrophy which is closely related to decreasing SRF nucleic translocation, consequently downregulating the SRF target genes involved in muscle growth and nutrition. The STARS/RhoA signaling pathway might contribute to this course by impacting SRF subcellular distribution.