MicroRNAs (miRNAs) are noncoding regulatory sequences that govern posttranscriptional inhibition of genes through binding mainly at regulatory regions. The regulatory mechanism of miRNAs are influenced by complex crosstalk among single nucleotide polymorphisms (SNPs) within miRNA seed region and epigenetic modifications. Circulating miRNAs exhibit potential characteristics as stable biomarker. Functionally, miRNAs are involved in basic regulatory mechanisms of cells including inflammation. Thus, miRNA dysregulation, resulting in aberrant expression of a gene, is suggested to play an important role in disease susceptibility. This review focuses on the role of miRNA as diagnostic marker in pathogenesis of lung inflammatory diseases and in cardiac remodelling events during inflammation. From recent reports, In this context, the information about the models in which miRNAs expression were investigated including types of biological samples, as well as on the methods for miRNA validation and prediction/definition of their gene targets are emphasized in the review. Besides disease pathogenesis, promising role of miRNAs in early disease diagnosis and prognostication is also discussed. However, some miRNAs are also indicated with protective role. Thus, identifications and usage of such potential miRNAs as well as disruption of disease susceptible miRNAs using antagonists, antagomirs, are imperative and may provide a novel therapeutic approach towards combating the disease progression.
The small microRNAs (miRNAs), 19–24 nucleotides, are noncoding, endogenous, single stranded, and evolutionarily conserved sequences. miRNAs downregulate gene expression at transcriptional or posttranscriptional level by binding to messenger RNAs (mRNAs) and preventing them from being translated into proteins [
miRNAs are transcribed by RNA polymerase II as long precursor (up to several hundred nucleotides) originating as RNA sequences with hairpin structure of about 70–100 nucleotides in length that constitutes the primary transcript of the miR/primary miRNAs (pri-miRNAs). These are further processed in the nucleus by microprocessor complex consisting of RNase III enzyme Drosha and double-stranded RNA binding protein, Pasha (also called DiGeorge syndrome Critical Region 8; DGCR8) to precursor-miRNAs (pre-miRNAs) of approximately 65 nucleotides. These pre-miRNAs are then exported to cytoplasm by exportin-5. This exportin-5 mediated transport to the cytoplasm is energy-dependent, which utilizes GTP bound to the Ran protein as cofactor [
In cytoplasm, the hairpin loop is removed and subsequently processed by the RNase III enzyme Dicer along with two double-stranded RNA (dsRNA) binding proteins, protein activator of PKR (PACT) and transactivation response RNA-binding protein (TRBP), leaving mature miRNA duplex (miRNA-
Biogenesis and role of micro-RNA (miRNA). The processing (★) step includes conversion of pri-miRNA to pre-miRNA through Drosha and DGCR8 and pre-miRNA to mature miRNA in the presence of dicer, PACT, and TRBP. In the mature miRNA, either of its strands is involved in RISC formation along with Ago-2. The complex is involved in transcriptional regulation (▲) by binding to site for transcription factors in the 5′-UTR, while it functions (▼) for mRNA degradation (by perfect pairing of its seed region) or transcriptional repression (by imperfect binding) of the target mRNA region. The mature circulatory miRNAs are also transported with microparticles such as membrane derived vesicles (exosomes and microvesicles), lipoproteins (HDL), or RNA binding proteins (RBPs) and remains protected from enzymatic degradation.
Regarding miRNA regulation, in addition to the major stages of control during miRNA biogenesis and its subcellular localization suggested by O’Connell et al. [
Mutations in miRNA transcripts are common and SNPs in pre-miRNAs could alter miRNA processing, expression, and/or binding to target mRNA and thus may have functional importance. Numerous reports have been made for the impact of single nucleotide polymorphism in miRNAs (mirSNPs) towards disease susceptibility; however, in this review, focus will be made on inflammatory lung and cardiovascular diseases.
In a case-control study for risk factor for asthma, SNPs demonstrated risk variant
Role of mirSNPs in lung inflammatory disease and cardiac remodeling events.
MicroRNA | SNP* risk variant (alleles) | Location | Putative role | References |
---|---|---|---|---|
Asthma | ||||
miR-146a | rs2910164*C (C/G) | Pre-miRNA region of miR-146a | Protection/lower risk of asthma | [ |
miR-149 | rs2292832*T (C/T) | Pre-miRNA region of miR-149 | Associated with lower risk of asthma | [ |
miR-152 family (miR-148a, -148b, and -152) | rs1063320*G (C/G) |
|
Protective against asthma only in children of asthmatic mothers | [ |
Chronic obstructive pulmonary disease (COPD) | ||||
miR-196a2 | rs11614913*C (C/T) | Pre-miRNA region of miR-196a2 | Target |
[ |
miR-499 | rs3746444*G (A/G) | Pre-miRNA regions of hsa-miR-499 | Decreased risk factor | [ |
Cystic fibrosis (CF) | ||||
miR-433 and -509-3p | rs10234329 (A/C) |
|
Mild CFTR mutation and may have a role in pathogenesis of CF | [ |
Pulmonary tuberculosis (PTB) | ||||
miR-499 | rs3746444*C (T/C) | Pre-miRNA regions of hsa-miR-499 | Disease susceptibility varies among different populations | [ |
miR-146a | rs2910164*G (G/C) | Precursor miRNA sequence of miR-146a | Disease susceptibility varies among different populations; regulates cytokine signaling and TLR pathways | [ |
Systemic lupus erythematosus (SLE) | ||||
miR-569 | rs1057233*T (T/C) |
|
High susceptibility to SLE | [ |
miR-146a | rs57095329*G (G/A) | Promoter of miR-146a primary transcript | Associated with SLE | [ |
miR-146a | rs2431697*T (C/T) | Intergenic region between |
Genetically associated with SLE in Europeans. | [ |
miR-3148 | rs3853839*G (G/C) |
|
Increased risk for SLE | [ |
Congenital heart disease | ||||
miR-196a2 | rs11614913*C (C/T) | Pre-miRNA region of miR-196a2 | Increased risk | [ |
Hypertension (HT) | ||||
miR-155 | rs5186*C (A/C) |
|
Risk factor for HT and other CVDs | [ |
miR-195 and -135 | rs9818870 (C/T) |
|
Risk factor for HT and other CVDs | [ |
miR-31 and -584 | rs7079 (C/A) |
|
Risk factor for HT | [ |
Coronary heart disease | ||||
miR-149 | rs4846049*G (G/T) |
|
Increased disease risk | [ |
Myocardial infarction | ||||
miR-149 precursor | rs71428439*G (A/G) | Affects miR-149 maturation and regulates Puma protein in apoptosis | [ | |
Dilated cardiomyopathy (DCM) | ||||
miR-196a2 | rs11614913*T (C/T) | Pre-miRNA region of miR-196a2 | Increased disease risk | [ |
miR-499 | rs3746444*G (A/G) | Pre-miRNA regions of hsa-miR-499 | Increased disease risk | [ |
Besides,
In an interesting report from pulmonary tuberculosis (PTB) patients, the roles of risk alleles in miRNAs were reported to vary for disease susceptibility among different populations. Investigating the association of genetic polymorphism with PTB, among the SNPs that regulate the Toll-like receptor- (TLR-) mediated signal pathway, it was shown that
For chronic systemic autoimmune disease, systemic lupus erythematosus (SLE),
Among the roles of mirSNPs in pathogenesis of cardiovascular diseases (CVDs), the mirSNPs
For coronary heart disease, the GG genotype of miR-149 rs4846049 (G/T) in the 3′-UTR of
These studies suggest the potentiality of genetic variant in disease susceptibility. In future, the allelic variant with low disease susceptibility could be explored in therapeutic mechanism to manage the disease progression.
miRNAs and antisense RNAs are able to direct epigenetic changes, such as histone modifications (e.g., H3K9me2, H3K9me3, and H3K27me3) and DNA methylation at specific loci, thereby evoking heritable and stable silencing of some mammalian imprinted genes. Histone modification involves Ago1 of RISC and the chromodomain protein Chp1 that recognizes H3K9me [
The downregulation of epigenetically controlled miRNAs as well as epi-miRNAs that target elements of the epigenetic machinery [
For the pathogenesis of autoimmune disease, such as systemic lupus erythematosus (SLE), the first report on role of DNA methylation was made during early 1980s with certain medications, such as hydralazine and procainamide inhibiting DNA methyltransferase1 (DNMT1) enzyme activity in CD4+ T cells [
Role of miRNAs in epigenetic regulation of lung inflammatory diseases and cardiac remodeling.
Disease and miRNA | Putative role in disease susceptibility | References |
---|---|---|
Idiopathic pulmonary fibrosis (IPF) | ||
miR-17~92 cluster | Hypermethylation and increased DNMT-1 expression: ↓miR-17~92 in lung biopsies and lung fibroblasts from IPF patients | [ |
SLE | ||
miR-21 | Targets RASGRP1 and alters DNMT1 activity; DNA hypomethylation in disease state | [ |
miR-29b | Targets DNMT1; hypomethylation | [ |
miR-126 | Inhibits DNMT1 | [ |
miR-148a | Inhibits DNMT1 | [ |
Myocardial infarction | ||
miR-21 | Acetylation regulates miR-21 promoter in myocardial infarction | [ |
Despite progress in the area of epigenetic modifications in other pathologies, the role of epigenetic factors affecting miRNA regulation in cardiac inflammatory diseases has still to be investigated. Possible differences among DNA methylation in cardiomyopathic and normal heart have been reported in humans [
The hallmark of fibrosis is tissue remodeling with excess deposition of extracellular matrix components, predominantly collagens. Recently, downregulation of miR-200 family (a–c) was reported in the lungs of mice with bleomycin-induced fibrosis; restoration of miR-200 expression reversed lung fibrosis via inhibiting
Role of miRNAs in mechanism of fibrosis. The downregulation of miR-200 and -192 (inhibits epithelial-mesenchymal transition, EMT) and miR-29 (prevents the deposition of extracellular matrix, ECM) promotes fibrosis. Further, miR-21 amplifies
An inflammation/injury to lung tissue ignites an innate immune response. Immune cells including macrophages, monocytes, and neutrophils migrate into the lungs to protect the damaging cells and activate antimicrobial peptides and T-cell responses. It further activates proinflammatory response involving cytokines and chemokines, such as
Asthma is a chronic inflammatory lung disease stimulated by aberrant allergen-specific CD4+ T helper-2 (TH2) secreting cytokines, IL-2, -4, -5, -9, and -13 in response to various stimuli, such as allergens, infections, and air pollutants. It is characterized by elevated serum IgE, airway hyperresponsiveness, mucus hypersecretion, and eosinophil accumulation in the lung [
miRNAs in inflammatory pulmonary diseases.
miRNA | Cell/tissue/body fluid (models) | miRNA regulation; validation method | Predicted target gene/possible effect | References |
---|---|---|---|---|
Asthma | ||||
let-7 family (miR-98, let-7d, -7f, -7g, and -7i) | A549 cells and primary cultured T-cells (C) | Down; qRT-PCR, northern blotting | 3′-UTR of IL-13 | [ |
let-7 (a-e) and miR-200 (200b, and 141) families | Exosomes from BALF (H) | Differentially expressed; microarray, qRT-PCR | let-7 is associated with IL-13; miR-200 regulate EMT | [ |
miR-20b | Alveolar macrophages (M) | Down; qRT-PCR, transfection assay | ⊥miR-20b: ↑VEGF | [ |
miR-21 | Whole lung, macrophage, dendritic cells (M) | Up; microarray, qRT-PCR, ISH | IL-12p35 | [ |
miR-106a | Mouse macrophage (M), Jurkat (T-cell), Raji (B-cell), THP-1 cells (C) | Up; qRT-PCR, northern blotting | IL-10; ⊥mmu-miR-106a: ↑IL-10, ↓asthma features | [ |
miR-126 | Lower airway tissue (M) | Up; microarray, qRT-PCR | OBF.1 | [ |
miR-133a | Bronchial smooth muscle cells and bronchial tissues of mice (C + M) | Down; qRT-PCR | ↓miR-133a: ↑RhoA | [ |
miR-145, -21, and let-7b | Lower airway tissue (M) | Up; qRT-PCR | ↓miR-145: ↓TH2 cytokine (IL-13, IL-5, IFN- |
[ |
miR-146a, -146b, and -28-5p | Human circulating T cells (H + C) | Down; microarray, qRT-PCR | Involved in T-cell activation | [ |
miR-146a, -146b, and -181a | Spleen CD4+ T lymphocytes (M) | Up; qRT-PCR | Th2 inflammation; proinflammatory factors in asthma | [ |
miR-155 | Cell line and macrophages (C + M) | Up; microarray, qRT-PCR, transfection assay | ⊥miR-20b; ↑Glucocorticoids | [ |
miR-221 | Mice mast cell line (M + C), ASM cells cultured from bronchial biopsies (C + H) | Up; qRT-PCR, transfection assay | Augment cell proliferation and IL-6 production | [ |
Chronic obstructive pulmonary disease (COPD) | ||||
let-7c and miR-125b | Induced sputum (H) | Down; qRT-PCR | ↓let-7c: ↑TNFR-II | [ |
miR-1 (muscle specific) | Muscle biopsy (H) | Down; qRT-PCR | IGF-1, HDAC4; ↓miR-1: ↓MRTF-SRF axis | [ |
miR-1, -499, -133, and -206 | Plasma (H) | Up in patient with stable COPD; qRT-PCR | miR-499 with markers of inflammation NF- |
[ |
miR-7 | Serum (H) | Up; qRT-PCR | — | [ |
mir-15/107 family (miR-15b, -424, and -107), -223, and -1274a | Lung tissue (H) | Up; microarray, qRT-PCR, ISH, and transfection assay | ↑miR-15b: ↓SMAD7, SMAD7, decorin, and SMURF2 | [ |
miR-18a and -365 | Cell line, Lung tissue |
Up; microarray, qRT-PCR, ISH, and transfection assay | — | [ |
miR-20a, -28-3p, -34c-5p, and -100 | Serum (H) | Down; qRT-PCR | — | [ |
miR-26b, -29b, -101, -106b, -133b, -152, -483-5p, -532-5p, and -629 | Plasma (H) | Down; TaqMan low-density array screening; qRT-PCR | miR-106b level negatively correlates with disease progression | [ |
miR-101 and -144 | Human bronchial epithelial cell line (H + C), mice lung (C + M) | Up; qRT-PCR, luciferase assay, ISH | ↑miR-101: ↓CFTR: ↑COPD | [ |
miR-146a | Primary lung fibroblasts |
Up; microarray, qRT-PCR | Degradation of COX-2 mRNA | [ |
miR-452 | Alveolar macrophages (H) | Down; microarray and qRT-PCR | ↑miR-452; ↓MMP12 | [ |
miR-923 and -937 | Lung tissue (H) | Down; microarray | Most downregulated in COPD | [ |
Cystic fibrosis (CF) | ||||
miR-14 and -494 | Several cell lines (C) | Up; qRT-PCR and luciferase assay | CFTR 3′-UTR | [ |
miR-101; -494 | HEK293 cell line (C) | Up; luciferase assays | ⊥CFTR | [ |
miR-101; -144 | Human bronchial epithelial cell line, mice lung (C + M) | Up; qRT-PCR, luciferase assay, and ISH | ↑miR-101: ↓ |
[ |
miR-126 | Bronchial epithelial cell line (C) | Down; qRT-PCR and luciferase assay | ↓mir-126: ↑TOM1, TOLLIP | [ |
miR-138 | Primary human airway epithelial cells (H + C) | Up; qRT-PCR and luciferase assay | Regulate CFTR | [ |
miR-145, -223, and -494 |
|
Up; qRT-PCR and luciferase assay | Regulate CFTR | [ |
miR-145 and -494 | Nasal epithelial tissues (H) | Up; qRT-PCR | ↑miR-145: ↓ |
[ |
miR-155 | Cell line, mouse (C + M) | Up; microarray and qRT-PCR | FGF7/KGF; ↑miR-155: ↓SHIP1, ↑IL-8 | [ |
miR-215 | Ex vivo CF lung epithelial cells (C) | Up; qRT-PCR | ↑IL-8 | [ |
miR-384, -494, and -1246 | Airway epithelial cells (C) | Down; qRT-PCR and luciferase assay | 3′- UTR of SLC12A2; ⊥CFTR | [ |
miR-509-3p and -494 | Primary human airway epithelial cells (H + C) | Up; qRT-PCR | Regulate CFTR expression | [ |
Idiopathic pulmonary fibrosis (IPF) | ||||
let-7d, miR-26, and miR-30 family | Lung biopsies and lung epithelial cells (M + C) | Down; microarray, qRT-PCR, and luciferase assay | ↓let-7d: ↑HMGA2 | [ |
miR-17~92 cluster | Lung biopsies (H) | Down; microarray and qRT-PCR | Metalloproteinases, collagen, and TGF | [ |
miR-21 | Lung biopsies and serum (M + H) | Up; microarray, qRT-PCR, ISH, and luciferase assay | ↑TGF- |
[ |
miR-29 | Lung tissues and pulmonary fibroblasts (M + C) | Down; microarray, qRT-PCR, ISH, and luciferase assay | Integrin, alpha 11; ADAMTS9; ADAM12, and nidogen-1 | [ |
miR-34a | Lung (M) | Up; microarray, qRT-PCR, ISH, and luciferase assay | — | [ |
miR-154, -134, -299–5p, -410, -382, -409–3p, -487b, -31, and -127 | Lung tissue + primary normal human lung fibroblast cells (H + C) | Up; microarray and qRT-PCR | SMAD3 to promoter of miR-154 | [ |
miR-200 family (a-c) | Lung (M) | Down | Inhibit |
[ |
Acute lung Injury (ALI) and inflammation | ||||
miR-127 | Mouse macrophage cell line (M + C) | Down; luciferase assay and microarray | IgG Fc |
[ |
Let-7; miR-21; -146; -155 | Lung (M) | Up; TaqMan low density arrays and qRT-PCR | Let-7 regulates IL-6; miR-146 –SMAD-4; miR-155 – SOCS-1 | [ |
miR-32*; -466-5p; -466-3p | Rat alveolar epithelial cell (R) | Up; microarray and qRT-PCR | — | [ |
miR-146a | Lung, macrophage cell line (R + C) | Up | ↑miR-146a: ⊥TNF- |
[ |
miR-181b | Cell line (C) | Up; microarray and qRT-PCR | ↑miR-181b: ⊥Importin- |
[ |
Pulmonary arterial hypertension (PAH) | ||||
miR-17/92 cluster (miR-17-5p, -20a) | hPAECs (H + C) | Up; qRT-PCR; reporter gene assay | ↑miR-17/92; ↓BMPR2 protein; ↑STAT3 | [ |
miR-21 | hPASMC (H + C) | Up; qRT-PCR and western blotting | ↑miR-21: ↓( |
[ |
miR-23b, -130a, and -191 | Blood buffy coat (H) | Up; qRT-PCR | miR-23b: ⊥BMPR1b; |
[ |
miR-124 | hPASMC (H + C) | Down; qRT-PCR | NFATc1, CAMTA1 and PTBP1; inhibitor of NFAT signaling | [ |
miR-145 | hPASMC (H + C) and mouse (M) | Up; qRT-PCR | ↑miR-145; BMPR2 mutations; vessel remodeling | [ |
miR-204 | hPASMC (H + C), mouse (M), and rat lung (R) | Down; qRT-PCR | ↑STAT3 |
[ |
miR-206 | Lung tissue + hPASMC |
Down; qRT-PCR | ↓ |
[ |
miR-424 and 503 | hPAECs (H + C), mouse (M) and rat (R) lung endothelial cell (C) | Down; qRT-PCR |
|
[ |
miR-451 and -1246 | Blood (H) | Down; qRT-PCR | miR-206: Titin; miR-1246: |
[ |
↑: increased level; ↓: decreased level; ⊥: inhibition. Investigating models: mouse (M), rat (R), cell culture (C), and human (H). ADAM metallopeptidase with thrombospondin type 1 motif, 9 (ADAMTS9); bone morphogenetic protein receptor type Ib (BMPR1b); epithelial-mesenchymal transition (EMT); fibroblast growth factor 2 (FGF2); fibroblast growth factor receptor 1 (FGFR1); human pulmonary arterial endothelial cells (HPAECs); in situ hybridization (ISH); insulin-like growth factor 1 (IGF-1); interleukin-1 receptor-associated kinase 1 (IRAK1); interleukin-8 (IL-8); histone deacetylase 4 (HDAC4); matrix metalloproteinase-12 (MMP-12); nuclear factor-
During the innate host response to allergens, miRNA expression with elemental regulatory signals has been linked to TLR signaling leading to activation of inflammatory pathways [
Chronic obstructive pulmonary disease (COPD) is characterized by both chronic inflammation in the airway and systemic inflammation. It is due to combination of emphysema and chronic asthmatic bronchitis leading to impairment of lung function. However, the molecular mechanism of COPD has not been fully elucidated [
In COPD, miRNAs such as miR-146a and miR-155 have been demonstrated with a regulatory role in inflammation. Cytokine-stimulated prostaglandin
Cystic fibrosis (CF) is a monogenic disease caused by mutations in the
Role of miRNAs in CF has been reported by several workers; among them, Oglesby et al. firstly described miR-126 in CF. In particular, miR-126 targets TOM1 protein, a negative regulator of
Idiopathic pulmonary fibrosis (IPF), defined as a specific form of chronic, progressive fibrosing interstitial pneumonia of unknown cause which is associated with the histopathologic and/or radiologic pattern of usual interstitial pneumonia (UIP) [
In IPF, the regulation of epithelial-mesenchymal transition (EMT) through inhibition of let-7 family members by
Despite the critical role of miRNA in inflammatory response, limited studies have focused on its role in inflammation-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) [
Pulmonary arterial hypertension (PAH) is a disease of the pulmonary vasculature characteristic by vascular remodeling associated with obliteration of pulmonary arterioles and formation of plexiform lesions composed of hyperproliferative endothelial and vascular smooth-muscle cells [
Inflammation plays a key role in cardiac function and remodeling during progression of cardiovascular diseases (CVDs). Biological processes affecting fibroblasts, extracellular matrix proteins, coronary vasculature, cardiac myocytes, and ionic channels are involved in this remodeling process [
miRNAs in cardiovascular diseases.
miRNA | Cell/tissue/body fluid (models) | Regulation | Validation method | Predicted target gene/possible effect | References |
---|---|---|---|---|---|
Atherosclerosis | |||||
miR-21 | Plaques and arteries (H) | Up | qRT-PCR | Signal transduction; regulation of transcription; vesicular transport | [ |
miR-26, -30, and -125a | Plaque tissue (H) | Up | qRT-PCR | Signal transduction; regulation of transcription; vesicular transport | [ |
miR-34a | Plaques and arteries (H) | Up | qRT-PCR | Signal transduction; regulation of transcription; vesicular transport | [ |
miR-146a | Plaques and arteries (H) | Up | qRT-PCR | Signal transduction; regulation of transcription; vesicular transport | [ |
miR-146b-5p | Plaques and arteries (H) | Up | qRT-PCR | Signal transduction; regulation of transcription; vesicular transport | [ |
miR-181b | Aortic intima (M) and plasma (H) | Down | qRT-PCR | Importin- |
[ |
miR-210 | Plaques and arteries (H) | Up | qRT-PCR | Potential biomarker | [ |
miR-712 | Mouse arterial endothelial cell |
Up | qRT-PCR | ↓TIMP3; ↑MMPs and ADAMs | [ |
Acute myocardial infarction (AMI) | |||||
Let-7b | Plasma (H) | Up | qRT-PCR | Differentiate AMI patients from healthy controls | [ |
miR-1 | Plasma (H), serum (M), and rat cardiac cells (R + C) | Up | qRT-PCR | Potential biomarker for AMI | [ |
miR-21 | Heart (R) | Down | qRT-PCR | Expression signature in early phase of AMI | [ |
miR-30a and -195 | Plasma (H) | Down | qRT-PCR | Differentiate AMI patients from healthy controls | [ |
miR-122 | Plasma (H) | Down | qRT-PCR | Potential biomarker for AMI | [ |
miR-133a and -b | Plasma and whole blood (H) | Up | qRT-PCR | Potential biomarker for AMI | [ |
miR-133 and -328 | Plasma and whole blood (H) | Up | qRT-PCR | Potential biomarker for AMI | [ |
miR-126 | Plasma (H) | Down | qRT-PCR | Potential biomarker for AMI | [ |
miR-155 | Monocytes, B-cells, T-cells (H), and knockout mice (M) | Up | miRNA profiling and qRT-PCR |
|
[ |
miR-208a and -499 | Plasma (H) | Up | qRT-PCR | Potential biomarker for AMI | [ |
Cardiac hypertrophy | |||||
miR-1 | Heart and skeletal muscle (M + R) and coronary artery cells (H) | Down | Nothern blot; qRT-PCR | Twinfilin-2 | [ |
miR-21 | Heart (M) | Up | Northern blot and qRT-PCR | — | [ |
miR-22 | Cardiac and muscle specific (M) | Up | qRT-PCR and western blot | Sirt1 and HDACY | [ |
miR-27b | Cardiomyocytes (M) | Up | Western blot and qRT-PCR | PPAR- |
[ |
miR-29a | Plasma (H) | Up | qRT-PCR | [ | |
miR-30 | Heart (R), cardiac tissue, and plasma (H) | Down | qRT-PCR |
|
[ |
miR-133 | Human (H), mouse (M), and rat (R) heart | Down | qRT-PCR and northern and western blot | RhoA, Cdc42, Nelf-A/WHSC2 | [ |
miR-155 | Leukocytes (M) | Up | — | Promotes cardiac inflammation, hypertrophy, and failure | [ |
miR-214 | Heart and cardiomyocytes (R) | Up | Luciferase assay and western blot | ↑miR-214; ↓EZH2 | [ |
Cardiac fibrosis | |||||
miR-21 | Cardiac fibroblast (H) | Up | — | SPRY1 | [ |
miR-21 | Cardiac myocytes (M) | Up | qRT-PCR | ⊥ |
[ |
miR-29 | Cells, mouse (M), and human (H) cardiac tissue | Up | miRNA microarray and qRT-PCR | Inflammatory cytokines | [ |
miR-133 | Heart (M) | Down | qRT-PCR | Col1A1 | [ |
miR-26a | Heart (M) | Down | qRT-PCR | CTGF and Col1A1 | [ |
miR-30 | Heart (H + R), cardiac fibroblast, and myocytes |
Up | qRT-PCR | ↑miR-30: ↓ |
[ |
miR-122 | Endomyocardial biopsies (H) | Down | qRT-PCR | ⊥TGF- |
[ |
Coronary artery disease (CAD) | |||||
miR-17/92a cluster, -126, -145, and -155 | Plasma (H) | Down | qRT-PCR | Potential biomarker for CAD | [ |
miR-21 | Endothelial cells and vessel wall (H) | Up | qRT-PCR | Potential biomarker for CAD | [ |
miR-106b/25 cluster, -17/92a cluster, -21/590-5p family, -126*, and -451 | Plasma (H) | Up | qRT-PCR | May affect inflammation, hypoxia, angiogenesis, apoptosis, and extracellular matrix (ECM) degradation | [ |
miR-126 | Endothelial cells and vessel wall (H) | Down | qRT-PCR | Potential biomarker for CAD | [ |
miR-133a | Endothelial cells and vessel wall (H) | Up | qRT-PCR | Potential biomarker for CAD | [ |
miR-135a | PBMC (H) | Up | qRT-PCR | Potential biomarker for CAD | [ |
miR-147 | PBMC (H) | Down | qRT-PCR | Potential biomarker for CAD | [ |
miR-155 | Endothelial cells and vessel wall (H) | Down | qRT-PCR | Potential biomarker for CAD | [ |
miR-208a | Endothelial cells and vessel wall (H) | Up | qRT-PCR | Potential biomarker for CAD | [ |
miR-221 | Endothelial cells and vessel wall (H) | Down | qRT-PCR | Potential biomarker for CAD | [ |
miR-370 | Endothelial cells and vessel wall (H) | Up | qRT-PCR | Potential biomarker for CAD | [ |
Heart failure | |||||
miR-1 | Muscle (H) | Down | qRT-PCR |
|
[ |
miR-16, -20b, -93, -106b, -223, and -423-5p | Plasma (R) | Up | qRT-PCR | Expression level changes during progression of hypertension-induced heart disease | [ |
miR-21 | Plasma, muscle, and heart tissue (H) | Up | qRT-PCR |
|
[ |
miR-23a | Plasma, muscle, and heart tissue (H) | Up | qRT-PCR |
|
[ |
miR-29b | Plasma, muscle, and heart tissue (H) | Down | qRT-PCR |
|
[ |
miR-30 | Plasma, muscle, and heart tissue (H) | Down | qRT-PCR |
|
[ |
miR-125 | Plasma, muscle, and heart tissue (H) | Up | qRT-PCR | — | [ |
miR-126 | Plasma (H) | Down | qRT-PCR | Useful biomarker for heart failure | [ |
miR-133 | Right atrial appendages (H) | Down | qRT-PCR |
|
[ |
miR-208a | Cardiac tissue and plasma (M + R) | Microarray profiling; qRT-PCR | [ | ||
miR-210 | Plasma (M + H), H9c2 (C), and mononuclear cells (M + H) | Up | qRT-PCR | Repress ISCU, leading to repression of mitochondrial respiration | [ |
miR-423-5p; -320, -22, and -92b | Plasma (H) and serum (H) | Up | qRT-PCR | Positive correlation of miR-423-5p with BNP and NT-proBNP | [ |
↑: increased level; ↓: decreased level; ⊥: inhibition. Investigating models: mouse (M), rat (R), cell culture (C), and human (H).A disintegrin and metalloproteases (ADAMs); collagen, type I, alpha 2 (Col1A2); collagen, type III, alpha 1 (Col3A1); connective tissue growth factor (CTGF); cytoplasmic SH2 domain containing protein tyrosine phosphatase (SHP2); enhancer of zeste homolog 2 (EZH2); Fas-associated death domain (FADD); iron-sulfur cluster assembly protein (ISCU); matrix metalloproteinases (MMPs); myocyte enhancer factor 2A (MEF2A); muscle ring-finger protein-1 (MuRF1); nuclear factor-kB (NF-kB); phosphatase and tensin homolog (PTEN); receptor-interacting protein 1 (RIP1); serum response factor (SRF); sirtuin 1 (Sirt1); proliferator-activated-receptor-
Recent reviews provide an overview of specific miRNA signatures with dysregulated level in CVDs [
Atherosclerosis (AS), a chronic inflammatory disease affecting major arteries, represents one of the causes of myocardial infarction, ischemic stroke, and peripheral artery disease [
Also, suppression of NF-
Acute myocardial infarction (AMI) is complex diseases that result from interplay between genetic and environmental factors [
Cardiac hypertrophy is characterized by an increase in cell size and/or myofibrils without change in myocyte number. Among miRNAs involved in myocardial hypertrophy/fibrosis, miR-133 was suggested to play a fundamental role. Its downregulation was associated with myocardial hypertrophy in mouse and humans [
Concerning circulatory miRNAs, miR-29a is a common marker for both cardiac hypertrophy and fibrosis reported to be upregulated in patients with hypertrophic cardiomyopathy [
The pathogenesis and clinical manifestations of heart failure are complex and involve disruption of normal mechanisms that regulate cardiomyocyte gene expression, growth, survival, and function. Cardiac interstitial cells and vascular cell also actively participate in disease process, resulting in altered myocyte-nonmyocyte signalling, cardiac fibrosis, and decreased vascular density. Currently only B-type natriuretic peptide (BNP) and pro-brain natriuretic peptide (NT-proBNP) are clinically established diagnostic biomarkers for heart failure. However, evaluation of HF progression along with the appropriate timing for therapeutic interventions in the HF patient is important from the perspective of clinical management [
In this context, signature expression patterns of specific miRNAs that are consistently aberrantly expressed in heart failure patients were described: miR-1, -29, -30, -126, and -133 are found to be downregulated in heart failure patients, whereas miR-21, -23a, -125, -210, -195, -199, and -423-5p are among the upregulated [
Among several miRNAs, miR-21 was implicated in several cardiac remodelling issues (Table
Aberrant miRNA expression has been associated with various human diseases and its determination can differentiate between normal and diseased tissue [
Circulating miRNAs, also known as extracellular miRNAs, are cellular free in nature. The origin of circulating miRNAs, stable existence in extracellular environment, and their distinct roles, has remained elusive [
Importantly, there are differences in miRNAs expression and abundance between the source, that is, serum and plasma and/or body fluids/other components [
The differential expression of tissue-specific miRNAs in circulation has been explored as potential circulating biomarkers for specific organ pathologies involved in lung or heart disease, for example, skeletal muscle specific miR-1, -499, -133, and -206 in plasma of COPD patients [
However, there are limitations and factors to be addressed prior to application of miRNAs in diagnostic purpose. These include optimal standardization in the approaches for obtaining sample (invasive/noninvasive), source (local/systemic), and nature (extra-cellular/cellular/tissue-based) of biological material and minimal variability in sample collection and its processing. Moreover, lack of data on miRNA specificity/sensitivity among different reports and its overlapping role in different diseases also hampers its applicability.
The preliminary step includes quality estimation of miRNA. Among the few possibilities, 2100 Bioanalyzer, a lab on-chip technology from Agilent Technologies, offers both qualitative and quantitative estimation of miRNAs. For miRNA discovery, high-throughput deep sequencing (next-generation sequencing) platforms such as HiSeq 2000/Genome Analyzer IIX/Solexa (Illumina), SOLiD (ABI), GS FLX+, or 454 sequencing (Roche) are available [
Most commonly used techniques for establishing miRNA signatures in body fluids include high throughput determination of differential miRNA gene expression using miRNA microarrays [
The optimal quantification of the target miRNAs involves data normalization using either stable reference genes under the study or accumulative values of the large scale miRNA-profiling data under study. However, as reference miRNAs (
For studying epigenetic modification, preliminary analysis involves methylated-DNA immunoprecipitation-chip (MeDIP-chip), validated differential methylation loci by bisulfate (BS) PCR and high throughput sequencing (BS-seq). The miRNA promoters in different cell types have been identified by genome-wide profiling of promoter associated chromatin marks through Dnase I hypersensitivity (DHS) mapping, chromatin immunoprecipitation (ChIP) followed by large-scale microarray analysis (DHS/ChIP-chip) or next-generation sequencing (DHS/ChIP-seq). DHS mapping identifies sites of open chromatin that are accessible to factors that influence gene expression. Active promoters are characterized by open chromatin regions enriched for both the H3K4me3 and H3K79me2 [
The use of miRNA as target for therapeutic tool has remained as challenge due to its redundancy that involves nonspecific targets. Antisense oligonucleotides primarily work as competitive inhibitors of miRNAs by binding to the mature miRNA strand and inducing degradation or stable duplex formation and making it unavailable for RISC formation. The microRNA-based therapeutic approaches have been recently summarized in several reviews [
miRNAs play crucial role in immune system development, maintenance, and function. miRNA dysregulation is implicated in inflammatory pulmonary diseases and cardiac remodeling. Studies of miRNAs role in disease pathomechanisms have been undergoing translation to diagnostic area. In this context, two approaches to exploitation of miRNAs as biomarkers have been emerging: (1) characterization of the miRNA pattern typical for a given disease/condition (i.e., expression profiling) and (2) determination of miRNAs present in body fluids (circulating miRNA), which relative stability may add advantage to their potential use as biomarkers.
Regarding potential therapeutic applications of miRNAs, several approaches may be used to control pathological miRNA dysregulation. These range from the inhibition of pathologically upregulated miRNAs by anti-miRNA oligonucleotides/anatagomirs or miRNA mimics to potential delivery of a miRNA to maintain its physiological level in case of its downregulation in a disease. However, development of targeted therapies has remained challenging due to their possibilities of nonspecific targets or alteration in the gene-miRNAs and miRNA-miRNA interacting network. Additionally, the epigenetic modifications along with environmental factors as well as mutation within the seed region of miRNA are among the major issues affecting the miRNA based transcriptional control. Therefore, it would be imperative to evaluate the complex regulatory circuit between miRNA, mirSNPs, and epigenetic modifications that modulate the expression of numerous genes in the genome. Additional strategies, such as understanding of genes and the mechanism regulating the miRNAs, are still needed for early detection of disease progression for improving patient outcomes in lung and heart diseases. Taken together, measurement of altered miRNA expression serves as useful noninvasive approach for the diagnosis and prognosis of respiratory and cardiovascular disease. Further, the unique role of miRNAs should be explored for better clinical practices towards disease management.
The authors declare that there is no conflict of interests regarding the publication of this paper.
This work was supported by IGA_PULF_2013_009, 2014_012; CZ.1.05/2.1.00/01.0030; and CZ.1.07/2.3.00/30.0041. The authors thank Dr. Giovanna Castoldi for helpful advice.