The role of MicroRNAs in COPD muscle dysfunction and mass loss: implications on the clinic

Non-Coding RNAs in Airway Diseases: A Brief Overview of Recent Data

Inflammation of the human lung is mediated in response to different stimuli (e.g., physical, radioactive, infective, pro-allergenic, or toxic) such as cigarette smoke and environmental pollutants. These stimuli often promote an increase in different inflammatory activities in the airways, manifesting themselves as chronic diseases (e.g., allergic airway diseases, asthma chronic bronchitis/chronic obstructive pulmonary disease, or even lung cancer). Non-coding RNA (ncRNAs) are single-stranded RNA molecules of few nucleotides that regulate the gene expression involved in many cellular processes. ncRNA are molecules typically involved in the reduction of translation and stability of the genes of mRNAs s. They regulate many biological aspects such as cellular growth, proliferation, differentiation, regulation of cell cycle, aging, apoptosis, metabolism, and neuronal patterning, and influence a wide range of biologic processes essential for the maintenance of cellular homeostasis. The relevance of ncRNAs in the pathogenetic mechanisms of respiratory diseases has been widely established and in the last decade many papers were published. However, once their importance is established in pathogenetic mechanisms, it becomes important to further deepen the research in this direction. In this review we describe several of most recent knowledge concerning ncRNA (overall miRNAs) expression and activities in the lung.

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.

An Analysis of Mechanisms for Cellular Uptake of miRNAs to Enhance Drug Delivery and Efficacy in Cancer Chemoresistance

Up until recently, it was believed that pharmaceutical drugs and their metabolites enter into the cell to gain access to their targets via simple diffusion across the hydrophobic lipid cellular membrane, at a rate which is based on their lipophilicity. An increasing amount of evidence indicates that the phospholipid bilayer-mediated drug diffusion is in fact negligible, and that drugs pass through cell membranes via proteinaceous membrane transporters or carriers which are normally used for the transportation of nutrients and intermediate metabolites. Drugs can be targeted to specific cells and tissues which express the relevant transporters, leading to the design of safe and efficacious treatments. Furthermore, transporter expression levels can be manipulated, systematically and in a high-throughput manner, allowing for considerable progress in determining which transporters are used by specific drugs. The ever-expanding field of miRNA therapeutics is not without its challenges, with the most notable one being the safe and effective delivery of the miRNA mimic/antagonist safely to the target cell cytoplasm for attaining the desired clinical outcome, particularly in miRNA-based cancer therapeutics, due to the poor efficiency of neo-vascular systems revolting around the tumour site, brought about by tumour-induced angiogenesis. This acquisition of resistance to several types of anticancer drugs can be as a result of an upregulation of efflux transporters expression, which eject drugs from cells, hence lowering drug efficacy, resulting in multidrug resistance. In this article, the latest available data on human microRNAs has been reviewed, together with the most recently described mechanisms for miRNA uptake in cells, for future therapeutic enhancements against cancer chemoresistance.

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.

Gga-let-7f-3p promotes apoptosis in selenium deficiency-induced skeletal muscle by targeting selenoprotein K

Selenoprotein K (SELENOK) is primarily observed in the endoplasmic reticulum, and serves to maintain the normal physiological functions of skeletal muscle. Skeletal muscle development and regeneration are associated with significant changes in the expression of specific microRNAs (miRNAs). Downregulated SELENOK expression is observed in chicken muscles deficient of Se. However, the mechanisms of miRNA regulation of SELENOK expression remain elusive. Here, deep sequencing was used to detect the miRNA profiles of muscle in Se deficient (-Se group) and normal (C group) chickens. A dual-luciferase reporter assay was adopted to verify the relationship between SELENOK and gga-let-7f-3p. In addition, gga-let-7f-3p was either overexpressed or knocked-down in chicken myoblasts. Furthermore, the cells were treated with N-acetyl-l-cysteine (NAC) or hydrogen peroxide (H2O2) in order to probe the factors involved in oxidative stress, endoplasmic reticulum stress (ERS) and apoptosis, respectively. Relative to the C group, there were 132 differentially expressed miRNAs (including 57 upregulated and 75 downregulated) in the muscles of the -Se group. The dual-luciferase reporter assay showed that SELENOK was a primary target of gga-let-7f-3p. It was also observed that the overexpression or knock-down of gga-let-7f-3p significantly influenced the SELENOK expression. Moreover, NAC blocked mimics of ga-let-7f-3p, thus inducing oxidative stress, ERS and apoptosis. Simultaneously, gga-let-7f-3p inhibitors blocked the stimulant effects caused by H2O2 in chicken myoblasts. Furthermore, Se deficiency downregulated the SELENOK protein expression and induced oxidative stress, ERS and apoptosis in chicken muscles. In conclusion, the gga-let-7f-3p-SELENOK pathway played a pivotal role in Se deficiency mediated muscle injuries through the induction of oxidative stress and ERS, ultimately promoting apoptosis.

MicroRNA-186 is associated with hypoxia-inducible factor-1α expression in chronic obstructive pulmonary disease

Background

MicroRNAs (miRNAs) are a family of small noncoding RNAs and are essential in the regulation of gene expression. Their impacts on gene expression have been reported in various diseases. The role of hypoxia‐inducible factor 1 alpha (HIF‐1α) in the development and progression of chronic obstructive pulmonary disease (COPD) has also been demonstrated. However, the role of microRNA‐186 (miR‐186) in relation to HIF in COPD is unknown.

Methods

Cell culture experiments were performed using human lung fibroblast cells (MRC‐5). Cell viability was determined by MTT and flow cytometry assays. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) and Western blot analysis were used to assess the expression levels of HIF‐1α and inflammatory cytokines. Dual‐luciferase reporter assays were used to reveal the correlation between miR‐186 and HIF‐1α.

Results

After miR‐186 transfection, the cell lines showed reduced proliferation and increased apoptosis. After overexpression of miR‐186, we found that the HIF‐1α expression level was reduced in MRC‐5 cells. We found that miR‐186 can affect apoptosis of inflammatory fibroblasts through the regulation of HIF‐1α and affect the downstream signaling pathways.

Conclusions

These data suggested that miR‐186 contributes to the pathogenesis of COPD and that miRNA‐186 may also affect the HIF‐1α‐dependent lung structure maintenance program.

Nucleic Acid-Based Therapeutics for Pulmonary Diseases

Nucleic acid-based therapeutics present huge potential in the treatment of pulmonary diseases ranging from lung cancer to asthma and chronic pulmonary diseases, which are often fatal and widely prevalent. The susceptibility of nucleic acids to degradation and the complex structure of lungs retard the effective pulmonary delivery of nucleic acid drug. To overcome these barriers, different strategies have been exploited to increase the delivery efficiency using chemically synthesized nucleic acids, vector encapsulation, proper formulation, and administration route. However, several limitations regarding off-target effects and immune stimulation of nucleic acid drugs hamper their translation into the clinical practice. Therefore, their successful clinical application will ultimately rely on well-developed carriers and methods to ensure safety and efficacy. In this review, we provide a comprehensive overview of the nucleic acid application for pulmonary diseases, covering action mechanism of the nucleic acid drugs, the novel delivery systems, and the current formulation for the administration to lungs. The latest advances of nucleic acid drugs under clinical evaluation to treat pulmonary disorders will also be detailed.

Bone remodeling induced by mechanical forces is regulated by miRNAs

The relationship between mechanical force and alveolar bone remodeling is an important issue in orthodontics because tooth movement is dependent on the response of bone tissue to the mechanical force induced by the appliances used. Mechanical cyclical stretch (MCS), fluid shear stress (FSS), compression, and microgravity play different roles in the cell differentiation and proliferation involved in bone remodeling. However, the underlying mechanisms are unclear, particularly the molecular pathways regulated by non-coding RNAs (ncRNAs) that play essential roles in bone remodeling. Amongst the various ncRNAs, miRNAs act as post-transcriptional regulators that inhibit the expression of their target genes. miRNAs are considered key regulators of many biologic processes including bone remodeling. Here, we review the role of miRNAs in mechanical force-induced bone metabolism.

MiR-3202 protects smokers from chronic obstructive pulmonary disease through inhibiting FAIM2: An in vivo and in vitro study

Previous study found the variable miR-3202 as a potential biomarker in smoker with or without chronic obstructive pulmonary disease (COPD). This study aims to identify the molecular involvement of miR-3202 in the pathophysiology of COPD. Level of miR-3202 in blood sample of non-smoker non-COPD(C), smoker without COPD(S), smoker with stable COPD(S-COPD) and smoker with acute exacerbation COPD(AE-COPD) was observed by quantitative real-time PCR. By bioinformatics prediction, Fas apoptotic inhibitory molecule 2 (FAIM2) was identified as a potential target of miR-3202. In vitro, human bronchial epithelial (HBE) cells and cigarette smoke extract (CSE) stimulated T lymphocytes were co-cultured. Cell proliferation and apoptosis of HBE cells were determinated. In vivo, rats were exposed in cigarette smoke for 30 days and expression of miR-3202 and FAIM2 in bronchia were detected. Results showed that The miR-3202 was down-regulated in S, S-COPD and AE-COPD group when compared with C group. Decreased level of miR-3202 was also observed in CSE treated T lymphocyte. Additionally, CSE stimulation increased INF-γ and TNF-α levels and FAIM2 expression whereas inhibited Fas and FasL expressions in T lymphocytes. However, these effects were significantly suppressed by miR-3202 overexpression and enhanced by miR-3202 inhibitor. Likely to exogenous miR-3202, FAIM2 knockdown significantly inhibited HBE cells apoptosis, as well as inhibited INF-γ and TNF-α levels. In COPD rats model, miR-3202 was reduced while FAIM2 was up-regulated accordingly. Here, results suggest that high level miR-3202 in T lymphocytes may protect epithelial cells through targeting FAIM2. MiR-3202 might be used as a notable biomarker of COPD.

Severity of COPD and its relationship with IL-10

BACKGROUND

The present study was designed to compare inflammatory and metabolic responses according to severity of airflow among patients with COPD and to verify the relationship between pulmonary function, body composition, metabolic and inflammatory profile.

METHODS

Fifty-one patients with mild to very severe COPD were recruited and divided according lung function in Mild-moderate (GOLD 1-2) n= 21; Severe (GOLD 3) n=25 and Very severe (GOLD 4) n=5. Patients were submitted to assessments of lung function (spirometry), functional exercise capacity (6-min walk test), body composition (Octopolar bioelectrical impedance), metabolic profile (glucose, triglycerides, total cholesterol, HDL-cholesterol and albumin (colorimetric assay)) and inflammatory profile (cytokines: IL-6, IL-10, TNF-α and IL-15 (ELISA)).

RESULTS

We found that patients in GOLD 3 group had lower levels of IL-10, triglycerides, visceral fat area, and higher IL-6 and IL-6/IL-10 ratio when compared to GOLD 1-2 patients. Additionally, GOLD 1-2 group presented negative correlation between TNF-α and HDL cholesterol (p= .01) and positive correlation between IL-15 and FEV₁/FVC (p=.01), while GOLD 3 group showed positive correlation between IL-6 and IL-10 (p< .01), IL-6 and total cholesterol (p<.01) and negative correlation between IL-10 and HDL-cholesterol (p=.01).

CONCLUSION

Our findings suggest that patients with severe COPD can exhibit compromised "inflammatory status", characterized by higher IL6, IL-6/IL-10 ratio and lower IL-10 concentration. Furthermore, IL-10 seems to be an interesting cytokine to be investigated in this kind of patients.

MicroRNA Dysregulation in Aging and Pathologies of the Skeletal Muscle

Skeletal muscle is one of the biggest organs of the body with important mechanistic and metabolic functions. Muscle homeostasis is controlled by environmental, genetic, and epigenetic factors. Indeed, MiRNAs, small noncoding RNAs robust regulators of gene expression, have and have been shown to regulate muscle homeostasis on several levels: through controlling myogenesis, muscle growth (hypertrophy) and atrophy, as well as interactions of muscle with other tissues. Given the large number of MiRNA target genes and the important role of MiRNAs in most physiological processes and various diseases, MiRNAs may have an enormous potential as therapeutic targets against numerous disorders, including pathologies of muscle. The purpose of this review is to present the current knowledge of the role of MiRNAs in skeletal muscle homeostasis and pathologies and the potential of MiRNAs as therapeutics for skeletal muscle wasting, with particular focus on the age- and disease-related loss of muscle mass and function.