Inhibition of miRNA-221 suppresses the airway inflammation in asthma

Heavy metal levels are positively associated with serum periostin and miRNA-125b levels, but inversely associated with miRNA-26a levels in pediatric asthma cases. A case-control study

BACKGROUND

The study investigated heavy metals levels [urinary cadmium (U-Cd), erythrocytic cadmium (E-Cd), urinary arsenic (U-As), and whole blood lead (WB-Pb)] in children with bronchial asthma (BA) and tested their associations with serum periostin, miRNA-125b and miRNA-26a levels, and with asthma severity clinically and laboratory [blood eosinophils count (BEC) and serum total immunoglobin E (IgE)]. Also, we tested cut-off points, for the studied parameters, to distinguish BA cases from healthy children.

METHODS

This case-control study included 158 children divided into control group; n = 72 and BA group; n = 86. Heavy metals were measured by an inductively coupled plasma-optical emission spectrophotometer. Serum periostin and IgE levels were measured by their corresponding ELISA kits. miRNAs relative expressions were estimated by RT-qPCR using the 2-ΔΔCT method.

RESULTS

Heavy metals, serum periostin, and miR-125b levels were significantly high in BA group (p < 0.001). Heavy metals levels correlated positively with serum periostin, miR-125b and IgE levels, BEC, and asthma severity. The reverse was observed regarding serum miR-26a levels. Receiver operating characteristics (ROC) curve analysis showed good to excellent abilities of U-Cd, E-Cd, U-As, WB-Pb, serum periostin, miRNA-125b, and miRNA - 26a, and total IgE levels to distinguish BA cases from healthy children.

CONCLUSIONS

Heavy metal toxicity in children is associated with BA severity, increased serum periostin and miRNA-125b levels, and decreased miRNA-26a levels. Specific measures to reduce children's exposure to heavy metals should be taken. Future research should consider blocking miRNA-125b action or enhancing miRNA-26a action to manage BA cases.

Epigenetic regulation of inflammation: The metabolomics connection

Epigenetic factors are considered the regulator of complex machinery behind inflammatory disorders and significantly contributed to the expression of inflammation-associated genes. Epigenetic modifications modulate variation in the expression pattern of target genes without affecting the DNA sequence. The current knowledge of epigenetic research focused on their role in the pathogenesis of various inflammatory diseases that causes morbidity and mortality worldwide. Inflammatory diseases are categorized as acute and chronic based on the disease severity and are regulated by the expression pattern of various genes. Hence, understanding the role of epigenetic modifications during inflammation progression will contribute to the disease outcomes and therapeutic approaches. This review also focuses on the metabolomics approach associated with the study of inflammatory disorders. Inflammatory responses and metabolic regulation are highly integrated and various advanced techniques are adopted to study the metabolic signature molecules. Here we discuss several metabolomics approaches used to link inflammatory disorders and epigenetic changes. We proposed that deciphering the mechanism behind the inflammation-metabolism loop may have immense importance in biomarkers research and may act as a principal component in drug discovery as well as therapeutic applications.

Sex-biased expression of selected chromosome x-linked microRNAs with potent regulatory effect on the inflammatory response in children with cystic fibrosis: A preliminary pilot investigation

Previous studies have reported sex disparity in cystic fibrosis (CF) disease, with females experiencing more pulmonary exacerbations and frequent microbial infections resulting in shorter survival expectancy. This concerns both pubertal and prepubertal females, which is in support to the prominent role of gene dosage rather than the hormonal status. The underlying mechanisms are still poorly understood. The X chromosome codes for a large number of micro-RNAs (miRNAs) that play a crucial role in the post-transcriptional regulation of several genes involved in various biological processes, including inflammation. However, their level of expression in CF males and females has not been sufficiently explored. In this study, we compared in male and female CF patients the expression of selected X-linked miRNAs involved in inflammatory processes. Cytokine and chemokine profiles were also evaluated at both protein and transcript levels and cross-analyzed with the miRNA expression levels. We observed increased expression of miR-223-3p, miR-106a-5p, miR-221-3p and miR-502-5p in CF patients compared to healthy controls. Interestingly, the overexpression of miR-221-3p was found to be significantly higher in CF girls than in CF boys and this correlates positively with IL-1β. Moreover, we found a trend toward lower expression in CF girls than in CF boys of suppressor of cytokine signaling 1 (SOCS1) and the ubiquitin-editing enzyme PDLIM2, two mRNA targets of miR-221-3p that are known to inhibit the NF-κB pathway. Collectively, this clinical study highlights a sex-bias in X-linked miR-221-3p expression in blood cells and its potential contribution to sustaining a higher inflammatory response in CF girls.

Advances and Highlights of miRNAs in Asthma: Biomarkers for Diagnosis and Treatment

Asthma is a heterogeneous inflammatory disease of the airways that causes breathing difficulties, episodes of cough and wheezing, and in more severe cases can greatly diminish quality of life. Epigenetic regulation, including post-transcriptional mediation of microRNAs (miRNAs), is one of the mechanisms behind the development of the range of asthma phenotypes and endotypes. As in every other immune-mediated disease, miRNAs regulate the behavior of cells that shape the airway structure as well as those in charge of the defense mechanisms in the bronchi and lungs, controlling cell survival, growth, proliferation, and the ability of cells to synthesize and secrete chemokines and immune mediators. More importantly, miRNAs are molecules with chemical and biological properties that make them appropriate biomarkers for disease, enabling stratification of patients for optimal drug selection and thereby simplifying clinical management and reducing both the economic burden and need for critical care associated with the disease. In this review, we summarize the roles of miRNAs in asthma and describe how they regulate the mechanisms of the disease. We further describe the current state of miRNAs as biomarkers for asthma phenotyping, endotyping, and treatment selection.

Recent Advances in Nanomaterials for Asthma Treatment

Asthma is a chronic airway inflammatory disease with complex mechanisms, and these patients often encounter difficulties in their treatment course due to the heterogeneity of the disease. Currently, clinical treatments for asthma are mainly based on glucocorticoid-based combination drug therapy; however, glucocorticoid resistance and multiple side effects, as well as the occurrence of poor drug delivery, require the development of more promising treatments. Nanotechnology is an emerging technology that has been extensively researched in the medical field. Several studies have shown that drug delivery systems could significantly improve the targeting, reduce toxicity and improve the bioavailability of drugs. The use of multiple nanoparticle delivery strategies could improve the therapeutic efficacy of drugs compared to traditional delivery methods. Herein, the authors presented the mechanisms of asthma development and current therapeutic methods. Furthermore, the design and synthesis of different types of nanomaterials and micromaterials for asthma therapy are reviewed, including polymetric nanomaterials, solid lipid nanomaterials, cell membranes-based nanomaterials, and metal nanomaterials. Finally, the challenges and future perspectives of these nanomaterials are discussed to provide guidance for further research directions and hopefully promote the clinical application of nanotherapeutics in asthma treatment.

The Crosstalk between FcεRI and Sphingosine Signaling in Allergic Inflammation

Sphingolipid molecules have recently attracted attention as signaling molecules in allergic inflammation diseases. Sphingosine-1-phosphate (S1P) is synthesized by two isoforms of sphingosine kinases (SPHK 1 and SPHK2) and is known to be involved in various cellular processes. S1P levels reportedly increase in allergic inflammatory diseases, such as asthma and anaphylaxis. FcεRI signaling is necessary for allergic inflammation as it can activate the SPHKs and increase the S1P level; once S1P is secreted, it can bind to the S1P receptors (S1PRs). The role of S1P signaling in various allergic diseases is discussed. Increased levels of S1P are positively associated with asthma and anaphylaxis. S1P can either induce or suppress allergic skin diseases in a context-dependent manner. The crosstalk between FcεRI and S1P/SPHK/S1PRs is discussed. The roles of the microRNAs that regulate the expression of the components of S1P signaling in allergic inflammatory diseases are also discussed. Various reports suggest the role of S1P in FcεRI-mediated mast cell (MC) activation. Thus, S1P/SPHK/S1PRs signaling can be the target for developing anti-allergy drugs.

The Role of Noncoding RNA in Airway Allergic Diseases through Regulation of T Cell Subsets

Allergic rhinitis and asthma are common airway allergic diseases, the incidence of which has increased annually in recent years. The human body is frequently exposed to allergens and environmental irritants that trigger immune and inflammatory responses, resulting in altered gene expression. Mounting evidence suggested that epigenetic alterations were strongly associated with the progression and severity of allergic diseases. Noncoding RNAs (ncRNAs) are a class of transcribed RNA molecules that cannot be translated into polypeptides and consist of three major categories, microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). Previous studies showed that ncRNAs were involved in the physiopathological mechanisms of airway allergic diseases and contributed to their occurrence and development. This article reviews the current state of understanding of the role of noncoding RNAs in airway allergic diseases, highlights the limitations of recent studies, and outlines the prospects for further research to facilitate the clinical translation of noncoding RNAs as therapeutic targets and biomarkers.

Dietary Acid Load Modulation of Asthma-Related miRNAs in the Exhaled Breath Condensate of Children

Individual nutrients and bioactive compounds have been implicated in the expression of microRNAs (miRNAs), which are related to inflammation and asthma. However, evidence about the impact of diet is scarce. Therefore, we aimed to assess the association between dietary acid load and asthma-related miRNA in the exhaled breath condensate (EBC) of school-aged children. This cross-sectional analysis included 150 participants aged 7 to 12 years (52% girls) from a nested case–control study, which randomly selected 186 children attending 71 classrooms from 20 public schools located in city of Porto, Portugal. Dietary data were collected by one 24 h-recall questionnaire. Dietary acid load was assessed using the potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores. Based on previous studies, eleven asthma-related miRNAs were chosen and analyzed in EBC by reverse transcription-quantitative real-time PCR. PRAL, NEAP and miRNAs were categorized as high or low according to the median. Logistic regression models were performed to assess the association between dietary acid load scores and miRNAs. Children in high dietary acid load groups (PRAL ≥ 14.43 and NEAP ≥ 55.79 mEq/day) have significantly increased odds of having high miR-133a-3p levels. In conclusion, higher dietary acid loads possibly modulate asthma-related miRNAs of school-aged children.

Epigenetic regulation of pediatric and neonatal immune responses

Epigenetic regulation of transcription is a collective term that refers to mechanisms known to regulate gene transcription without changing the underlying DNA sequence. These mechanisms include DNA methylation and histone tail modifications which influence chromatin accessibility, and microRNAs that act through post-transcriptional gene silencing. Epigenetics is known to regulate a variety of biological processes, and the role of epigtenetics in immunity and immune-mediated diseases is becoming increasingly recognized. While DNA methylation is the most widely studied, each of these systems play an important role in the development and maintenance of appropriate immune responses. There is clear evidence that epigenetic mechanisms contribute to developmental stage-specific immune responses in a cell-specific manner. There is also mounting evidence that prenatal exposures alter epigenetic profiles and subsequent immune function in exposed offspring. Early life exposures that are associated with poor long-term health outcomes also appear to impact immune specific epigenetic patterning. Finally, each of these epigenetic mechanisms contribute to the pathogenesis of a wide variety of diseases that manifest during childhood. This review will discuss each of these areas in detail. IMPACT: Epigenetics, including DNA methylation, histone tail modifications, and microRNA expression, dictate immune cell phenotypes. Epigenetics influence immune development and subsequent immune health. Prenatal, perinatal, and postnatal exposures alter immune cell epigenetic profiles and subsequent immune function. Numerous pediatric-onset diseases have an epigenetic component. Several successful strategies for childhood diseases target epigenetic mechanisms.

Emerging Advances of Non-coding RNAs and Competitive Endogenous RNA Regulatory Networks in Asthma

Asthma is a chronic inflammatory disease characterized by airway remodeling and bronchial hyperresponsiveness. A variety of effector cells and cytokines jointly stimulate the occurrence of inflammatory response in asthma. Although the pathogenesis of asthma is not entirely clear, the possible roles of non-coding RNAs (ncRNAs) have been recently demonstrated. NcRNAs are non-protein-coding RNA molecules, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), which are involved in the regulation of a variety of biological processes. Mounting studies have shown that ncRNAs play pivotal roles in the occurrence and progression of asthma via competing endogenous RNA (ceRNA) regulatory networks. However, the specific mechanism and clinical application of ncRNAs and ceRNA regulatory networks in asthma have not been fully elucidated, which are worthy of further investigation. This paper comprehensively summarized the current progress on the roles of miRNAs, lncRNAs, circRNAs, and ceRNA regulatory networks in asthma, which can provide a better understanding for the disease pathogenesis and is helpful for identifying novel biomarkers for asthma.

Spotlight on microRNAs in allergy and asthma

In past 10 years, microRNAs (miRNAs) have gained scientific attention due to their importance in the pathophysiology of allergic diseases and their potential as biomarkers in liquid biopsies. They act as master post‐transcriptional regulators that control most cellular processes. As one miRNA can target several mRNAs, often within the same pathway, dysregulated expression of miRNAs may alter particular cellular responses and contribute, or lead, to the development of various diseases. In this review, we give an overview of the current research on miRNAs in allergic diseases, including atopic dermatitis, allergic rhinitis, and asthma. Specifically, we discuss how individual miRNAs function in the regulation of immune responses in epithelial cells and specialized immune cells in response to different environmental factors and respiratory viruses. In addition, we review insights obtained from experiments with murine models of allergic airway and skin inflammation and offer an overview of studies focusing on miRNA discovery using profiling techniques and bioinformatic modeling of the network effect of multiple miRNAs. In conclusion, we highlight the importance of research into miRNA function in allergy and asthma to improve our knowledge of the molecular mechanisms involved in the pathogenesis of this heterogeneous group of diseases.

MiR-21-5p in Macrophage-Derived Exosomes Targets Smad7 to Promote Epithelial Mesenchymal Transition of Airway Epithelial Cells

Background

Asthma is usually associated with airway inflammation and airway remodeling. Epithelial mesenchymal transition (EMT) often occurs in airway remodeling. The purpose of this study is to identify the effect of miR-21-5p and Smad7 signaling pathway in macrophage-derived exosomes on EMT of airway epithelial cells.

Methods

HE staining and Masson staining were used to verify the successful establishment of the asthma model. The levels of epithelial cell adhesion factor and stromal cell markers were detected by Western blot. The levels of miR-21-5p were detected by qRT-PCR. The expression of miR-21-5p in lung tissue was further verified by fluorescence in situ hybridization (FISH). Exosome morphology was observed by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Luciferase reporter assay was applied to analyze the interaction of miR-21-5p with Smad7.

Results

The expression of miR-21-5p was upregulated in macrophages of rats in vivo with OVA-induced asthma. In vitro cultured alveolar macrophages stimulated by LPS could secrete exosomes with high levels of miR-21-5p. The exosome-derived miR-21-5p promotes EMT in rat tracheal epithelial cells through TGFβ1/Smad signaling pathway by downregulating Smad7. This process can be blocked by miR-21-5p inhibitor.

Conclusion

Rat alveolar macrophages produced high levels of miR-21-5p-containing exosomes, which transported miR-21-5p to tracheal epithelial cells, thus promoting EMT through TGF-β1/Smad signaling pathway by targeting Smad7.

Therapeutic Potential of microRNA Against Th2-associated Immune Disorders

MicroRNAs (miRNAs) are short ~18-22 nucleotide, single-stranded, non-coding RNA molecules playing a crucial role in regulating diverse biological processes and are frequently dysregulated during disease pathogenesis. Thus, targeting miRNA could be a potential candidate for therapeutic invention. This systemic review aims to summarize our current understanding regarding the role of miRNAs associated with Th2-mediated immune disorders and strategies for therapeutic drug development and current clinical trials.

Genetics and Epigenetics in Asthma

Asthma is one of the most common respiratory disease that affects both children and adults worldwide, with diverse phenotypes and underlying pathogenetic mechanisms poorly understood. As technology in genome sequencing progressed, scientific efforts were made to explain and predict asthma’s complexity and heterogeneity, and genome-wide association studies (GWAS) quickly became the preferred study method. Several gene markers and loci associated with asthma susceptibility, atopic and childhood-onset asthma were identified during the last few decades. Markers near the ORMDL3/GSDMB genes were associated with childhood-onset asthma, interleukin (IL)33 and IL1RL1 SNPs were associated with atopic asthma, and the Thymic Stromal Lymphopoietin (TSLP) gene was identified as protective against the risk to TH2-asthma. The latest efforts and advances in identifying and decoding asthma susceptibility are focused on epigenetics, heritable characteristics that affect gene expression without altering DNA sequence, with DNA methylation being the most described mechanism. Other less studied epigenetic mechanisms include histone modifications and alterations of miR expression. Recent findings suggest that the DNA methylation pattern is tissue and cell-specific. Several studies attempt to describe DNA methylation of different types of cells and tissues of asthmatic patients that regulate airway remodeling, phagocytosis, and other lung functions in asthma. In this review, we attempt to briefly present the latest advancements in the field of genetics and mainly epigenetics concerning asthma susceptibility.

MicroRNAs: future biomarkers and targets of therapy in asthma?

PURPOSE OF REVIEW

MicroRNAs (miRNAs) are small noncoding RNA molecules that are considered one of the fundamental regulatory mechanisms of gene expression. They are involved in many biologic processes, such as signal transduction, cell proliferation and differentiation, apoptosis and stress responses. The purpose of this review is to present recent knowledge about the role of miRNAs in asthma and outline possible applications of miRNAs.

RECENT FINDINGS

A core set of miRNAs involved in asthma includes downregulated let-7 family, miR-193b, miR-375 as well as upregulated miR-21, miR-223, miR-146a, miR-142-5p, miR-142-3p, miR-146b and miR-155. Recently it has been shown that most of the involved miRNAs increase secretion of Th2 cytokines, decrease secretion of Th1 cytokines, promote differentiation of T cells towards Th2 or play a role in hyperplasia and hypertrophy of bronchial smooth muscle cells. The profiles of miRNAs correlate with clinical characteristics, including lung function, phenotype and severity of asthma.

SUMMARY

Recent publications confirmed crucial regulatory role of miRNAs in the pathomechanism of asthma. Some single miRNAs or their sets hold the promise for their use as asthma biomarkers facilitating diagnosis or prediction of treatment outcomes. They are also possible target of future therapies. The studies in this field are lacking though.

miR-135a inhibits airway inflammatory response in asthmatic mice via regulating JAK/STAT signaling pathway

The objective of this study was to investigate the inhibitory effect of miR-135a in regulating JAK/STAT signaling pathway on airway inflammation in asthmatic mice. An asthma model was established by sensitization and stimulation with ovalbumin (OVA), and the corresponding drug intervention was given from the day of stimulation by means of nasal drops. Airway hyperresponsiveness was tested. The content of miR-135a in the lung tissue of mice was detected by RT-PCR. The pathological changes of lung tissue were evaluated by HE staining. Tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-5, and eotaxin in bronchoalveolar lavage fluid (BALF) and lung tissue were detected by ELISA and immunohistochemistry, respectively. The expression of JAK/STAT signaling pathway-related protein in lung tissue was detected by western blot. To further validate the effect of miR-135a overexpression on the JAK/STAT signaling pathway, pathway activators and inhibitors were added. Compared with the OVA group, the airway hyperresponsiveness of the mice was significantly decreased after treatment with the miR-135a agonist. The expression of miR-135a was significantly increased in the lung tissue and the pathological changes of the lung tissue were alleviated. The contents of TNF-α, IL-6, IL-5, and eotaxin in BALF and lung tissues were decreased. The expression of JAK/STAT signaling pathway-related proteins p-JAK3/JAK3, p-STAT1/STAT1, and p-STAT3/STAT3 were significantly reduced in lung tissue (P<0.05). Addition of JAK inhibitor AG490 reduced airway inflammation in asthmatic mice. miR-135a agonists inhibit airway inflammation in asthmatic mice by regulating the JAK/STAT signaling pathway.

MiR-135b Alleviates Airway Inflammation in Asthmatic Children and Experimental Mice with Asthma via Regulating CXCL12

OBJECTIVE

To clarify the possible influence of miR-135b on CXCL12 and airway inflammation in children and experimental mice with asthma.

METHODS

The expressions of miR-135b and CXCL12 were detected using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) in the serum of asthmatic children. Besides, the experimental asthmatic mice were established by aerosol inhalation of ovalbumin (OVA) followed by the treatment with agomiR-135b and antagomir-135b. Pathological changes of lung tissues were observed via HE staining and PAS staining. Besides, the airway hyperresponsiveness of mice was elevated and bronchoalveolar lavage fluid (BALF) was isolated for cell categorization and counting. The inflammatory cytokines in BALF were determined by enzyme-linked immunosorbent assay (ELISA), and the infiltration of Th17 cells in lung tissues was measured using flow cytometry.

RESULTS

MiR-135b was downregulated and CXCL12 was upregulated in asthmatic children and mice. Overexpression of miR-135b may down-regulate CXCL12 expression in the lung of OVA mice, resulting in significant decreases in inflammatory infiltration, hyperplasia of goblet cell, airway hyperresponsiveness, cell quantity, as well as the quantity of eosinophilic granulocytes, neutrophils and lymphocytes in BALF. Also, the levels of inflammatory cytokines (IL-4, IL-5, IL-13 and IL-17) and the ratio of Th17 cells and IL-17 levels in lung tissues were decreased. However, miR-135b downregulation reversed these changes in OVA mice.

CONCLUSION

MiR-135b may inhibit immune responses of Th17 cells to alleviate airway inflammation and hyperresponsiveness in asthma possibly by targeting CXCL12, showing the potential value in asthma treatment.

An endothelial microRNA-1-regulated network controls eosinophil trafficking in asthma and chronic rhinosinusitis

BACKGROUND

Airway eosinophilia is a prominent feature of asthma and chronic rhinosinusitis (CRS), and the endothelium plays a key role in eosinophil trafficking. To date, microRNA-1 (miR-1) is the only microRNA known to be regulated in the lung endothelium in asthma models.

OBJECTIVE

We sought to determine the role of endothelial miR-1 in allergic airway inflammation.

METHODS

We measured microRNA and mRNA expression using quantitative RT-PCR. We used ovalbumin and house dust mite models of asthma. Endothelium-specific overexpression of miR-1 was achieved through lentiviral vector delivery or induction of a transgene. Tissue eosinophilia was quantified by using Congo red and anti-eosinophil peroxidase staining. We measured eosinophil binding with a Sykes-Moore adhesion chamber. Target recruitment to RNA-induced silencing complex was assessed by using anti-Argonaute2 RNA immunoprecipitation. Surface P-selectin levels were measured by using flow cytometry.

RESULTS

Serum miR-1 levels had inverse correlations with sputum eosinophilia, airway obstruction, and number of hospitalizations in asthmatic patients and sinonasal tissue eosinophilia in patients with CRS. IL-13 stimulation decreased miR-1 levels in human lung endothelium. Endothelium-specific overexpression of miR-1 reduced airway eosinophilia and asthma phenotypes in murine models and inhibited IL-13-induced eosinophil binding to endothelial cells. miR-1 recruited P-selectin, thymic stromal lymphopoietin, eotaxin-3, and thrombopoietin receptor to the RNA-induced silencing complex; downregulated these genes in the lung endothelium; and reduced surface P-selectin levels in IL-13-stimulated endothelial cells. In our asthma and CRS cohorts, miR-1 levels correlated inversely with its target genes.

CONCLUSION

Endothelial miR-1 regulates eosinophil trafficking in the setting of allergic airway inflammation. miR-1 has therapeutic potential in asthmatic patients and patients with CRS.

Emerging role of non-coding RNAs in allergic disorders

RNA transcripts that not undergo translation into polypeptides recently came into focus of research. Long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) comprise the most important groups of these transcripts. LncRNAs have a length over 200 nucleotides and like mRNAs, have regulated transcription in a tissue specific manner. Biogenesis and function of lncRNAs is related to cell differentiation, response to stimuli and regulation of immune responses. LncRNAs can interact with both miRNAs and mRNAs. MiRNAs are characterized by a length of 22-24 nucleotides. MiRNAs regulate expression of genes at the post-transcriptional level. LncRNAs together with miRNAs are considered as regulators of the immune system. Alterations in their biogenesis is an important mechanism in the development immune related disorders. CircRNAs are products of aberrant maturation of protein-coding transcripts in a process of back-splicing, in which a single strand RNA molecule attains a closed circle shape. Despite a low expression, some circRNA were found to titrate miRNAs and interfere with maturation of legitimate protein-coding transcripts. We summarize the current knowledge on the role of non-coding transcripts in allergic disorders: asthma, atopic dermatitis, allergic rhinitis and urticaria. The reviewed data suggest lncRNA and miRNAs as therapeutic targets and biomarkers of allergic disorders.

MicroRNA-221 Modulates Airway Remodeling via the PI3K/AKT Pathway in OVA-Induced Chronic Murine Asthma

Background

Airway remodeling is one of the most important pathological features of chronic asthma. This study aimed to determine whether microRNA-221 (hereafter, miR-221) can affect airway remodeling in a mouse model of ovalbumin (OVA)-induced chronic asthma.

Methods

Adeno-associated viruses (AAVs) “Bearing miR-221 sponges” were used to downregulate miR-221 in asthmatic mice. Staining with hematoxylin and eosin (H&E), Masson trichrome, and periodic acid–Schiff reagent was used to assess histological changes. The affected signaling pathway in mouse airway smooth muscle cells (ASMCs) was also identified by gene chip technology. A PI3K/AKT-inhibitor (LY294002) was used to confirm the role of the pathway in ASMCs.

Results

The inhibition of miR-221 in a murine asthma model was found to reduce airway hyper-responsiveness, mucus metaplasia, airway inflammation, and airway remodeling (p < 0.05). Furthermore, miR-221 was found to regulate collagen deposition in the extracellular matrix (ECM) of ASMCs. Bioinformatics analysis and western blot analysis confirmed that the PI3K-AKT pathway was involved in ECM deposition in ASMCs.

Conclusion

miR-221 might play a crucial role in the mechanism of remodeling via the PI3K/AKT pathway in chronic asthma and it could be considered as a potential target for developing therapeutic strategies.

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.

The impact of microRNAs on alterations of gene regulatory networks in allergic diseases

Allergic diseases including asthma are worldwide on the rise and contribute significantly to health expenditures. Allergic diseases are prototypic diseases with a strong gene by environment interaction component and epigenetic mechanisms might mediate the effects of the environment on the disease phenotype. MicroRNAs, small non-coding RNAs (miRNAs), regulate gene expression post-transcriptionally. Functional single-stranded miRNAs are generated in multiple steps of enzymatic processing from their precursors and mature miRNAs are included into the RNA-induced silencing complex (RISC). They imperfectly base-pair with the 3'UTR region of targeted genes leading to translational repression or mRNA decay. The cellular context and microenvironment as well the isoform of the mRNA control the dynamics and complexity of the regulatory circuits induced by miRNAs that regulate cell fate decisions and function. MiR-21, miR-146a/b and miR-155 are among the best understood miRNAs of the immune system and implicated in different diseases including allergic diseases. MiRNAs are implicated in the induction of the allergy reinforcing the Th2 phenotype (miR-19a, miR-24, miR-27), while other miRNAs promote regulatory T cells associated with allergen tolerance or unresponsiveness. In the current chapter we describe in detail the biogenesis and regulatory function of miRNAs and summarize current knowledge on miRNAs in allergic diseases and allergy relevant cell fate decisions focusing mainly on immune cells. Furthermore, we evoke the principles of regulatory loops and feedback mechanisms involving miRNAs on examples with relevance for allergic diseases. Finally, we show the potential of miRNAs and exosomes containing miRNAs present in several biological fluids that can be exploited with non-invasive procedures for diagnostic and potentially therapeutic purposes.

Siglec1 enhances inflammation through miR-1260-dependent degradation of IκBα in COPD

It has been documented that sialic acid-binding Ig-like lectin 1 (Siglec1) is a cell surface protein with a variety of functions in the immune system. In the present study, we evaluated whether Siglec1 plays a role in chronic obstructive pulmonary disease (COPD). Results show that the expression of Siglec1 was increased in the lung of COPD rats, and that Siglec1 overexpression greatly enhanced the expression of inflammatory cytokines including tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β) and IL-6 in cigarette smoke extract (CSE)-treated NR8383 cells, a rat lung-derived macrophage cell line. Notably, the proinflammatory effect of Siglec1 was totally inhibited by overexpression of nuclear factor of κ light polypeptide gene enhancer in B-cells inhibitor α (IκBα). Importantly, Siglec1 overexpression increased miR-1260, which then degraded IκBα through its 3' untranslated region (3'UTR). Further study demonstrated that miR-1260 inhibitor attenuated inflammation in CSE-induced rat COPD lung and in CSE-treated NR8383 cells. Finally, the inhibitory effect of miR-1260 on inflammation was totally lost when IκBα was inhibited. In summary, the present study demonstrated that Siglec1 exerts its proinflammatory effects through increasing miR-1260, leading to decreased expression of IκBα.

Aberrant MicroRNAomics in Pulmonary Complications: Implications in Lung Health and Diseases

Over the last few decades, evolutionarily conserved molecular networks have emerged as important regulators in the expression and function of eukaryotic genomes. Recently, miRNAs (miRNAs), a large family of small, non-coding regulatory RNAs were identified in these networks as regulators of endogenous genes by exerting post-transcriptional gene regulation activity in a broad range of eukaryotic species. Dysregulation of miRNA expression correlates with aberrant gene expression and can play an essential role in human health and disease. In the context of the lung, miRNAs have been implicated in organogenesis programming, such as proliferation, differentiation, and morphogenesis. Gain- or loss-of-function studies revealed their pivotal roles as regulators of disease development, potential therapeutic candidates/targets, and clinical biomarkers. An altered microRNAome has been attributed to several pulmonary diseases, such as asthma, chronic pulmonary obstructive disease, cystic fibrosis, lung cancer, and idiopathic pulmonary fibrosis. Considering the relevant roles and functions of miRNAs under physiological and pathological conditions, they may lead to the invention of new diagnostic and therapeutic tools. This review will focus on recent advances in understanding the role of miRNAs in lung development, lung health, and diseases, while also exploring the progress and prospects of their application as therapeutic leads or as biomarkers.

Development and validation of exhaled breath condensate microRNAs to identify and endotype asthma in children

Detection and quantification of microRNAs (miRNAs) in exhaled breath condensate (EBC) has been poorly explored. Therefore we aimed to assess miRNAs in EBC as potential biomarkers to diagnose and endotype asthma in school aged children. In a cross sectional, nested case control study, all the asthmatic children (n = 71) and a random sample of controls (n = 115), aged 7 to 12 years, attending 71 classrooms from 20 local schools were selected and arbitrarily allocated to the development or validation set. Participants underwent skin-prick testing, spirometry with bronchodilation, had exhaled level of nitric oxide determined and EBC collected. Based on previous studies eleven miRNAs were chosen and analyzed in EBC by reverse transcription-quantitative real-time PCR. Principal component analysis was applied to identify miRNAs profiles and associations were estimated using regression models. In the development set (n = 89) two clusters of miRNAs were identified. After adjustments, cluster 1 and three of its clustered miRNAs, miR-126-3p, miR-133a-3p and miR-145-5p were positively associated with asthma. Moreover miR-21-5p was negatively associated with symptomatic asthma and positively associated with positive bronchodilation without symptoms. An association was also found between miR-126-3p, cluster 2 and one of its clustered miRNA, miR-146-5p, with higher FEF25-75 reversibility. These findings were confirmed in the validation set (n = 97) where two identical clusters of miRNAs were identified. Additional significant associations were observed between miR-155-5p with symptomatic asthma, negative bronchodilation with symptoms and positive bronchodilation without symptoms. We showed that microRNAs can be measured in EBC of children and may be used as potential biomarkers of asthma, assisting asthma endotype establishment.

A translational perspective on epigenetics in allergic diseases

The analysis of epigenetic modifications in allergic diseases has recently attracted substantial interest because epigenetic modifications can mediate the effects of the environment on the development of or protection from allergic diseases. Furthermore, recent research has provided evidence for an altered epigenomic landscape in disease-relevant cell populations. Although still in the early phase, epigenetic modifications, particularly DNA methylation and microRNAs, might have potential for assisting in the stratification of patients for treatment and complement or replace in the future biochemical or clinical tests. The first epigenetic biomarkers correlating with the successful outcome of immunotherapy have been reported, and with personalized treatment options being rolled out, epigenetic modifications might well play a role in monitoring or even predicting the response to tailored therapy. However, further studies in larger cohorts with well-defined phenotypes in specific cell populations need to be performed before their implementation. Furthermore, the epigenome provides an interesting target for therapeutic intervention, with microRNA mimics, inhibitors, and antisense oligonucleotides being evaluated in clinical trials in patients with other diseases. Selection or engineering of populations of extracellular vesicles and epigenetic editing represent novel tools for modulation of the cellular phenotype and responses, although further technological improvements are required. Moreover, interactions between the host epigenome and the microbiome are increasingly recognized, and interventions of the microbiome could contribute to modulation of the epigenome with a potential effect on the overall goal of prevention of allergic diseases.

MicroRNA-221 is overexpressed in the equine asthmatic airway smooth muscle and modulates smooth muscle cell proliferation

Airway wall remodeling, including hyperplasia and hypertrophy of smooth muscle (ASM) cells leading to an increased smooth muscle mass, is considered central to asthma. However, molecular pathways responsible for ASM remodeling remain poorly understood. MicroRNAs (miRNAs) have emerged as key regulators of inflammatory and repair processes affecting the lungs and can downregulate protein expression by inhibiting target mRNA translation. We therefore hypothesized that miRNAs are involved in ASM remodeling in asthma by modulating ASM proliferation. We have analyzed the expression of miRNAs in bronchial smooth muscle from asthmatic horses during disease exacerbation and remission and from controls. Their involvement in ASM cell proliferation was then studied. Our results shown that miR-26a, miR-133, and miR-221 were upregulated in ASM from horses with asthma exacerbation compared with asthma remission and controls. MiR-221 induced cell hyperproliferation and reduced the expression of contractile gene markers in ASM cells. These changes were associated with the decreased mRNA expression of cell cycle regulatory genes (p53, p21, and p27). In conclusion, we demonstrated for the first time an upregulation of miR-221 in asthmatic airway smooth muscle and confirm the involvement of miR-221 in ASM cell proliferation by regulation of the cell cycle arrest genes. Targeting miR-221 network genes may represent a novel approach for the treatment of ASM remodeling in asthma.

MicroRNAs: Potential Biomarkers and Targets of Therapy in Allergic Diseases?

MicroRNAs (miRNAs) are small non-coding RNA molecules that are 18-22 nucleotides long and highly conserved throughout evolution. Currently, they are considered one of the fundamental regulatory mechanisms of genes expression. It has been demonstrated that miRNAs are involved in many biologic processes, such as signal transduction, cell proliferation and differentiation, apoptosis and stress responses. More recently, the role of miRNA has also been revealed in numerous immunological and inflammatory disorders, including allergic inflammation. Specific miRNA profiles were demonstrated in asthma, allergic rhinitis and atopic dermatitis. A core set of miRNAs involved in atopic diseases include upregulated miR-21, miR-223, miR-146a, miR-142-5p, miR-142-3p, miR-146b, miR-155 and downregulated let-7 family, miR-193b and miR-375. Most of the involved miRNAs increase secretion of Th2 cytokines (miR-1248, miR-146b), decrease secretion of Th1 cytokines (miR-513-5p, miR-625-5p) or promote differentiation of T cells towards Th2 (miR-21, miR-19a). In asthma miR-140-3p, miR-708 and miR-142-3p play a role in hyperplasia and hypertrophy of bronchial smooth muscle cells. Some single miRNAs or, more probably, their sets hold the promise for their use as biomarkers of atopic diseases. They are also promising target of future therapies.

Crucial Role of Extracellular Vesicles in Bronchial Asthma

Extracellular vesicles (EVs) are circulating vesicles secreted by various cell types. EVs are classified into three groups according to size, structural components, and generation process of vesicles: exosomes, microvesicles, and apoptotic bodies. Recently, EVs have been considered to be crucial for cell-to-cell communications and homeostasis because they contain intracellular proteins and nucleic acids. Epithelial cells from mice suffering from bronchial asthma (BA) secrete more EVs and suppress inflammation-induced EV production. Moreover, microarray analyses of bronchoalveolar lavage fluid have revealed that several microRNAs are useful novel biomarkers of BA. Mesenchymal stromal cell-derived EVs are possible candidates of novel BA therapy. In this review, we highlight the biologic roles of EVs in BA and review novel EV-targeted therapy to help understanding by clinicians and biologists.

Involvement of microRNAs in physiological and pathological processes in asthma

Asthma is the most common respiratory disease accompanied by lung inflammatory disorders. The main symptoms are airway obstruction, chronic inflammation due to mast cell and eosinophil activity, and the disturbance of immune responses mostly mediated by the Th2 response. Genetic background and environmental factors also contribute to the pathogenesis of asthma. Today, microRNAs (miRNAs) are known as remarkable regulators of gene expression. As a small group of noncoding single-strand RNAs, mature miRNAs (~21 nucleotides) modulate the gene expression by targeting complement RNAs at both transcriptional and posttranscriptional levels. The role of miRNAs in the pathogenesis of many diseases such as allergies, asthma, and autoimmunity has been vastly studied. This review provides a thorough research update on the role of miRNAs in the pathogenesis of asthma and their probable role as diagnostic and/or therapeutic biomarkers.

miR-221 participates in the airway epithelial cells injury in asthma via targeting SIRT1

AIM OF THE STUDY

To investigate the role of microRNA-221 (miR-221) in the airway epithelial cell injury in asthma and delineate the underlying mechanism that may involve with SIRT1.

MATERIALS AND METHOD

Bronchial epithelial cells from asthma patients and healthy controls were obtained by bronchoscopic brushing. The miR-221 and SIRT1 mRNA level in collected cells were detected by qRT-CPR. BEAS2B cell lines were cultured in vitro. In order to up-regulate miR-221 and SIRT1, miR-221 mimic and pcDNA3.1-SIRT1 vector was transfected into BEAS2B cells, respectively. The expression changes of miR-221 and SIRT1 after transfection was observed by qRT-PCR and Western blot. The target relationship between miR-221 and SIRT1 was confirmed using dual-luciferase reporter assay.The cell viability changes after transfection was measured using cellTiter-blue reagent. The apoptosis rate was detected by flow cytometry.

RESULT

Compared with healthy controls, miR-221 expression significantly increased in bronchial epithelial cells from patients subjects. In contrast, the level of SIRT1 mRNA reduced in the bronchial epithelial cell from asthma patients. In vitro, up-regulation of miR-221 could inhibit the expression of SIRT1 both at mRNA and protein level in BEAS2B cells. A negative correlation between miR-221 and SIRT1 mRNA in samples from patients was confirmed and dual-luciferase reporter assay showed that miR-221 directly binds to the 3'UTR of SIRT1 mRNA. Overexpression of miR-221 or SIRT1 knockdown could inhibit proliferation but induce apoptosis in BEAS2B cells. Moreover, up-regulation of SIRT1 could antagonize miR-221's inhibitory effect.

CONCLUSION

miR-221 may participate in the airway epithelial cells injury in asthma via targeting SIRT1.

The role of microRNAs in chronic respiratory disease: recent insights

Chronic respiratory diseases encompass a group of diverse conditions affecting the airways, which all impair lung function over time. They include cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and asthma, which together affect hundreds of millions of people worldwide. MicroRNAs (miRNAs), a class of small non-coding RNAs involved in post-transcriptional gene repression, are now recognized as major regulators in the development and progression of chronic lung disease. Alterations in miRNA abundance occur in lung tissue, inflammatory cells, and freely circulating in blood and are thought to function both as drivers and modifiers of disease. Their importance in lung pathology has prompted the development of miRNA-based therapies and biomarker tools. Here, we review the current literature on miRNA expression and function in chronic respiratory disease and highlight further research that is needed to propel miRNA treatments for lung disorders towards the clinic.

Intranasal instillation of miR‑410 targeting IL‑4/IL‑13 attenuates airway inflammation in OVA‑induced asthmatic mice

Asthma is a common chronic inflammatory respiratory disease characterised by airway inflammation and hyperresponsiveness. The present study was designed to clarify the effect of intranasal miR-410 administration in an ovalbumin (OVA)-induced murine model of asthma. It was found that miR-410 expression was significantly decreased in the lungs of OVA-induced asthmatic mice (P<0.05) and miR-410 was overexpressed via intranasal instillation. Bioinformatics indicated that the 3′-untranslated regions of interleukin (IL)-4 and IL-13 messenger RNAs (mRNAs) contain miR-410 binding sites. The IL-4 and IL-13 genes were confirmed to be miR-410-regulated using the dual-luciferase reporter assay. Additionally, intranasal administration of miR-410 markedly attenuated airway inflammation and reduced infiltration of inflammatory cells into bronchoalveolar lavage fluid (P<0.05) as determined by bronchoalveolar lavage fluid analysis. Moreover, miR-410 significantly decreased the lung expression of IL-4 and IL-13 (P<0.05), although the levels of mRNAs encoding IL-4 and IL-13 in lungs did not change significantly as determined by real-time PCR analysis. In conclusion, we found that intranasal administration of miR-410 effectively inhibited airway inflammation in OVA-induced asthmatic mice by targeting IL-4 and IL-13 at the post-transcriptional level. miR-410 is thus a promising treatment for allergic asthma.

Innate lymphoid cells in organ fibrosis

Innate lymphoid cells (ILCs) are a recently identified family of lymphoid effector cells. ILCs are mainly clustered into 3 groups based on their unique cytokine profiles and transcription factors typically attributed to the subsets of T helper cells. ILCs have a critical role in the mucosal immune response through promptly responding to pathogens and producing large amount of effector cytokines of type 1, 2, or 3 responses. In addition to the role of early immune responses against infections, ILCs, particularly group 2 ILCs (ILC2), have recently gained attention for modulating remodeling and fibrosis especially in the mucosal tissues. Herein, we overview the current knowledge in this area, highlighting roles of ILCs on fibrosis in the mucosal tissues, especially focusing on the gut and lung. We also discuss some new directions for future research by extrapolating from knowledge derived from studies on Th cells.

Association of the miR-196a2, miR-146a, and miR-499 Polymorphisms with Asthma Phenotypes in a Korean Population

BACKGROUND

MicroRNAs (miRNAs) modulate expressions of inflammatory genes, thereby regulating inflammatory responses. Single nucleotide polymorphisms (SNPs) in miRNAs could affect their efficiency in binding to messenger RNAs (mRNAs).

OBJECTIVE

We investigated the associations of miRNA SNPs with asthma phenotypes. miR-196a2 (rs11614913 T>C), miR-146a (rs2910164 C>G), and miR-499 (rs3746444 A>G) were genotyped in 347 asthma patients and 172 normal healthy controls (NCs).

RESULTS

The CT/CC genotype of miR-196a2 rs11614913 was associated with eosinophilic asthma (p = 0.004) and a higher sputum eosinophil count compared with the TT genotype (p = 0.003). The CG/GG genotype of miR-146a rs2910164 tended to be associated with higher bronchial hyperresponsiveness to methacholine (PC₂₀) compared with the CC genotype. The AG/GG genotype of miR-499 rs3746444 was associated with higher predicted values of forced expiratory volume in 1 s (%FEV₁) compared with the AA genotype (p = 0.008).

CONCLUSIONS

Genetic polymorphisms in miR-196a2, miR-146a, and miR-499 could be potential biomarkers for asthma phenotypes and targets for asthma treatments in a Korean population.

The role of regulatory RNAs (miRNAs) in asthma

INTRODUCTION

Recently, a great deal of attention has been paid to the investigation of regulatory functions of microRNA. Currently, many different mechanisms involved in the pathogenesis of asthma are known, but the whole picture of pathogenesis has not yet been studied.

CONCLUSIONS

MicroRNAs play an important role in the regulation of many cellular processes. Undoubtedly, these regulatory molecules are involved in the pathogenesis of asthma, and therefore can be potential targets for treatment.

Persistent induction of goblet cell differentiation in the airways: Therapeutic approaches

Dysregulated induction of goblet cell differentiation results in excessive production and retention of mucus and is a common feature of several chronic airways diseases. To date, therapeutic strategies to reduce mucus accumulation have focused primarily on altering the properties of the mucus itself, or have aimed to limit the production of mucus-stimulating cytokines. Here we review the current knowledge of key molecular pathways that are dysregulated during persistent goblet cell differentiation and highlights both pre-existing and novel therapeutic strategies to combat this pathology.

MicroRNA Profiling in Asthma: Potential Biomarkers and Therapeutic Targets

Asthma is a heterogeneous chronic inflammatory disorder in which different endotypes contribute to define clinical inflammatory phenotypes. MicroRNAs (miRNAs) are a group of minute, endogenous 22-25 nt RNA elements that join to particular mRNAs to reduce translation and increase messenger RNA degradation. miRNAs operate in post-transcriptional control and regulate physiological and pathological processes in several illnesses. The purpose of this work is to review and discuss the current knowledge about the function of miRNAs in asthma, focusing particularly on their biological properties, pathophysiologic actions, and possible use as markers and treatments for asthma.

Non-Coding RNAs in Pediatric Airway Diseases

Non-coding RNAs (ncRNAs) are involved in the regulation of numerous biological processes and pathways and therefore have been extensively studied in human diseases. Previous reports have shown that non-coding RNAs play a crucial role in the pathogenesis and aberrant regulation of respiratory diseases. The altered expression of microRNAs (miRNAs) and long non-coding RNAs in blood and also locally in sputum or exhaled breath condensate influences lung function, immune response, and disease phenotype and may be used for the development of biomarkers specific for airway disease. In this review, we provide an overview of the recent works studying the non-coding RNAs in airway diseases, with a particular focus on chronic respiratory diseases of childhood. We have chosen the most common chronic respiratory condition—asthma—and the most severe, chronic disease of the airways—cystic fibrosis. Study of the altered expression of non-coding RNAs in these diseases may be key to better understanding their pathogenesis and improving diagnosis, while also holding promise for the development of therapeutic strategies using the regulatory potential of non-coding RNAs.

Small interfering RNA directed against microRNA-155 delivered by a lentiviral vector attenuates asthmatic features in a mouse model of allergic asthma

Asthma is a chronic T helper type 2 (Th2) cell-mediated inflammatory disease characterized by airway hyperresponsiveness (AHR) and airway inflammation. Although the majority of patients with asthma can achieve a good level of control with existing treatments, asthma runs a chronic course and the effectiveness of current treatment is not satisfactory for certain patients. MicroRNAs (miRNAs) are short noncoding RNAs that suppress gene expression at the post-transcriptional level; their role in regulating allergic inflammation remains largely unknown. The present study aimed to explore the role of miRNA-155 in the pathogenesis of asthma and its potential as a target for treatment. The expression of miRNA-155 increased in ovalbumin-sensitized and challenged mice compared with control mice, and lentiviral vector-delivered small interfering (si)RNA targeting miRNA-155 resulted in reduced AHR, airway inflammation and Th2 cytokine production. The data from the present study indicate that miRNA-155 serves an important role in the pathogenesis of asthma, and that lentiviral vector-delivered siRNA targeting miRNA-155 may serve as a novel approach for the treatment of allergic asthma.

Novel Modulators of Asthma and Allergy: Exosomes and MicroRNAs

Intercellular communication is crucial to the immune system response. In the recent years, the discovery of exosomes has changed the way immune response orchestration was understood. Exosomes are able to operate as independent units that act as mediators in both physiological and pathological conditions. These structures contain proteins, lipidic mediators, and nucleic acids and notoriously include microRNAs (miRNAs). miRNAs are short RNA sequences (around 19-22 nucleotides) with a high phylogenetic conservation and can partially or totally regulate multiple mRNAs, inhibiting protein synthesis. In respiratory diseases such as asthma and allergic sensitization, exosomes released by several cell types and their specific content perform crucial functions in the development and continuation of the pathogenic mechanisms. Released exosomes and miRNAs inside them have been found in different types of clinical samples, such as bronchoalveolar lavage fluids and sputum supernatants, providing new data about the environmental factors and mediators that participate in the inflammatory responses that lead to the exacerbation of asthma. In this review, we summarize our current knowledge of the role of exosomes and miRNAs in asthma and allergic sensitization, paying attention to the functions that both exosomes and miRNAs are described to perform through the literature. We review the effect of exosomes and miRNAs in cells implicated in asthma pathology and the genes and pathways that they modify in them, depicting how their behavior is altered in disease status. We also describe their possible repercussion in asthma diagnosis through their possible role as biomarkers. Therefore, both exosomes and miRNAs can be viewed as potential tools to be added to the arsenal of therapeutics to treat this disease.

Role of Sphingosine-1-Phosphate in Mast Cell Functions and Asthma and Its Regulation by Non-Coding RNA

Sphingolipid metabolites are emerging as important signaling molecules in allergic diseases specifically asthma. One of the sphingolipid metabolite, sphingosine-1-phosphate (S1P), is involved in cell differentiation, proliferation, survival, migration, and angiogenesis. In the allergic diseases, alteration of S1P levels influences the differentiation and responsiveness of mast cells (MCs). S1P is synthesized by two sphingosine kinases (SphKs), sphingosine kinase 1, and sphingosine kinase 2. Engagement of IgE to the FcεRI receptor induces the activation of both the SphKs and generates S1P. Furthermore, SphKs are also essential to FcεRI-mediated MC activation. Activated MCs export S1P into the extracellular space and causes inflammatory response and tissue remodeling. S1P signaling has dual role in allergic responses. Activation of SphKs and secretion of S1P are required for MC activation; however, S1P signaling plays a vital role in the recovery from anaphylaxis. Several non-coding RNAs have been shown to play a crucial role in controlling the MC-associated inflammatory and allergic responses. Thus, S1P signaling pathway and its regulation by non-coding RNA could be explored as an exciting potential therapeutic target for asthma and other MC-associated diseases.

Inhibition of MicroRNA-21 by an antagomir ameliorates allergic inflammation in a mouse model of asthma

AIM OF THE STUDY

MicroRNA-21 (miR-21) is up-regulated during allergic airway inflammation, reflecting a Th2 immune response. We investigated the effects of an miR-21 antagomir and its mechanism of action in a mouse model of acute bronchial asthma.

MATERIALS AND METHODS

BALB/c mice were sensitized and challenged with ovalbumin (OVA). The anti-miR-21 antagomir was administered by intranasal inhalation from the day of sensitization. Changes in cell counts, Th2 cytokine levels in bronchoalveolar (BAL) fluid, and airway hyper-responsiveness (AHR) were examined. Histopathological changes and expression levels of miR-21 in lung tissues were analyzed. The mechanism of action of the antagomir was investigated by counting CD4⁺/CD8^- T cells in splenocytes and by measuring the expression levels of transcription factors associated with T cell polarization.

RESULTS

MiR-21 expression was selectively down-regulated in the lung tissues of mice treated with anti-miR-21. The antagomir suppressed AHR compared with that of the OVA-challenged and scrambled RNA-treated groups. It also reduced the total cell and eosinophil counts in BAL fluid and the levels of Th2 cytokines, including IL-4, IL-5, and IL-13. The direct target of miR-21, IL-12p35, was induced in the antagomir-treated group, decreasing the CD4⁺/CD8^- T cell proportions in splenocytes. The levels of transcription factors involved in the Th2-signaling pathway were reduced in lung tissues on treatment with the antagomir.

CONCLUSIONS

The miR-21 antagomir suppresses the development of allergic airway inflammation in a mouse model of acute bronchial asthma, inhibiting Th2 activation. These results suggest that this antagomir might be useful for treating bronchial asthma.

Oligonucleotide Therapy for Obstructive and Restrictive Respiratory Diseases

Inhaled oligonucleotide is an emerging therapeutic modality for various common respiratory diseases, including obstructive airway diseases like asthma and chronic obstructive pulmonary disease (COPD) and restrictive airway diseases like idiopathic pulmonary fibrosis (IPF). The advantage of direct accessibility for oligonucleotide molecules to the lung target sites, bypassing systemic administration, makes this therapeutic approach promising with minimized potential systemic side effects. Asthma, COPD, and IPF are common chronic respiratory diseases, characterized by persistent airway inflammation and dysregulated tissue repair and remodeling, although each individual disease has its unique etiology. Corticosteroids have been widely prescribed for the treatment of asthma, COPD, and IPF. However, the effectiveness of corticosteroids as an anti-inflammatory drug is limited by steroid resistance in severe asthma, the majority of COPD cases, and pulmonary fibrosis. There is an urgent medical need to develop target-specific drugs for the treatment of these respiratory conditions. Oligonucleotide therapies, including antisense oligonucleotide (ASO), small interfering RNA (siRNA), and microRNA (miRNA) are now being evaluated both pre-clinically and clinically as potential therapeutics. The mechanisms of action of ASO and siRNA are highly target mRNA specific, ultimately leading to target protein knockdown. miRNA has both biomarker and therapeutic values, and its knockdown by a miRNA antagonist (antagomir) has a broader but potentially more non-specific biological outcome. This review will compile the current findings of oligonucleotide therapeutic targets, verified in various respiratory disease models and in clinical trials, and evaluate different chemical modification approaches to improve the stability and potency of oligonucleotides for the treatment of respiratory diseases.

Changes in the Expression of MicroRNA in the Buildup Phase of Wasp Venom Immunotherapy: A Pilot Study

BACKGROUND

Allergen-specific immunotherapy is the most effective method of treatment in allergy to wasp venom. However, its mechanism of action is still not fully understood. The aim of this study is to describe changes in microRNA (miRNA) expression in patients undergoing the buildup phase of venom immunotherapy.

METHODS

The study group comprised 7 adult patients with a history of severe systemic reactions after stinging by a wasp. In all patients, sensitization to wasp venom had been confirmed by skin tests and serum IgE. The buildup phase of wasp venom immunotherapy (VIT) was conducted according to an ultrarush protocol. In blood samples collected before and 24 h after completing the VIT buildup phase, 740 miRNAs were assessed.

RESULTS

Of the 740 miRNAs, 440 were detected in the study group, and in 5 expression was significantly changed after the buildup phase of VIT: miR-370, miR-539, miR-502-3p, miR-299, and miR-29c. Another 62 miRNAs changed 2-fold in some patients (nonsignificant), including increases in miR-143 (stimulating FOXp3 expression) and let-7d (reducing expression of IL-13, IL-6, and TLR4), and decreases in proinflammatory miR-301, miR-146b, miR-106, and miR-485.

CONCLUSIONS

Several changes in miRNA expression have been found as a result of the buildup phase of wasp VIT, with lower expression of some miRNAs involved in allergic inflammation and higher expression of those possibly involved in tolerance induction. However, the role of the most significant changes is uncertain.

MicroRNA-223 affects IL-6 secretion in mast cells via the IGF1R/PI3K signaling pathway

In this study, we aimed to assess the effects of microRNA-223 (miR-223) on interleukin-6 (IL-6) secretion in mast cells and determine the underlying molecular mechanisms. Mast cells (P815) were transfected with miR-223 lentiviral vector and miR-223 inhibitor. miR-223 expression was then evaluated using reverse transcription-quantitative PCR (RT-qPCR). IL-6 levels in the supernatant were analyzed using enzyme-linked immunosorbent assay. The signaling pathways in mast cells with downregulated miR-223 were initially evaluated by gene chip. Downregulation of miR-223 and its target gene was tested using a luciferase reporter assay. The expression of phosphate-AKT (p-AKT) and its target protein insulin-like growth factor-1 receptor (IGF1R) was assessed by western blot analysis. Phosphatidylinositol 3-kinase (PI3K)-inhibitor (LY294002) and insulin-like growth factor-1 (IGF1) were used to determine the effect of miR-223 on IL-6 secretion in mast cells. The results showed that microRNA-223 reduced IL-6 concentration in the mast cells. The gene chip results predicted an induction of the PI3K-AKT signaling pathway in the mast cells. Luciferase reporter assay confirmed IGF1R gene to be a target of miR-223. The p-AKT and IGF1R levels increased following miR-223 downregulation in mast cells. In addition, the specific PI3K‑inhibitor LY294002 decreased IL-6 secretion. Incubation with IGF1 resulted in the induction of IL-6 secretion in miR-223‑expressing mast cells. In conclusion, it was shown that miR-223 reduces IL-6 secretion in mast cells by inhibiting the IGF1R/PI3K signaling pathway.

microRNA and Allergy

Allergy is a common hypersensitivity disorder of the immune system, which, along with other factors, is also subjected to regulation by microRNAs. The most common allergic diseases are allergic rhinitis, asthma, atopic dermatitis, and food allergy, which all are multifactorial and very heterogeneous conditions, highlighting the need for more individualized treatment techniques. More particular key questions in relation to allergic diseases are how microRNAs influence the differentiation, polarization, plasticity and functions of T helper and other immune cells, as well as the development of immune tolerance. In addition, microRNAs can affect allergic inflammation and tissue remodeling through their functions in epithelial and other tissue cells. Among immune system-related microRNAs, miR-21, miR-146a, and miR-155 are the most intensively studied and have convincingly been demonstrated to regulate immune responses and tissue inflammation in allergic diseases. Further characterization of microRNA functions is important, as similar to other conditions, the modulation of microRNA expression could potentially be used for therapeutic purposes in allergic diseases in the future. In addition, miRNAs could be implemented as biomarkers for endotyping complex allergic conditions.

MiR-221 promotes IgE-mediated activation of mast cells degranulation by PI3K/Akt/PLCγ/Ca(2+) pathway

Mast cells play a pivotal role in the immediate reaction in asthma. In a previous study, it was found that MicroRNA-221 (miR-221) was associated with asthma. Hence, in the present study, the role and the potential mechanisms of miR-221 on immunoglobulin E (IgE)-mediated activation of mast cells degranulation were investigated. MiR-221 expression was first quantified by qRT-PCR in IgE-mediated activation of mast cells. RBL-2H3 cells were then transfected with miR-221 mimic or miR-221 inhibitor, the IgE-mediated degranulation was detected in mast cells. The influence of miR-221 on expression of phospholipase C gamma (PLCγ1), p-PLCγ1, protein kinase B (Akt), phospho-Akt (p-Akt), inhibitor of kappa B (IκB-α), and phospho-IκB-α (p-IκB-α) were examined by Western blot, whereas free calcium ion (Ca(2+)) level was measured by flow cytometry and NF-κB expression was determined by EMSA. Phosphoinositide 3-kinase (PI3K)-inhibitor (LY294002) and NF-κB-inhibitor [pyrrolidine dithiocarbamate (PDTC)] were used to investigate the role of PI3K/Akt pathway and NF-κB in miR-221 promoting IgE-mediated activation of mast cells degranulation. The expression of miR-221 was upregulated in IgE-mediated activation of mast cells, and it was overexpressed in miR-221 mimic transfected cells. The degranulation was found to be significantly increased in miR-221 overexpressed cells while it was found to be significantly decreased in miR-221 downregulated cells. The expression of p-PLCγ1, p-Akt, p-IκB-α as well as NF-κB and Ca(2+) release were increased in miR-221 overexpressed cells. PI3K-inhibitor (LY294002) could rescue the promotion of degranulation caused by miR-221 in IgE-mediated activation of mast cells. However, NF-κB-inhibitor (PDTC) could not rescue the promotion of degranulation caused by miR-221 in IgE-mediated activation of mast cells. MiR-221 promotes IgE-mediated activation of mast cells degranulation by PI3K/Akt/PLCγ/Ca(2+) signaling pathway, in a non-NF-κB dependent manner.

MiR-3162-3p Is a Novel MicroRNA That Exacerbates Asthma by Regulating β-Catenin

Asthma is a common chronic respiratory disease. In a previous study, we found several circulating microRNA signatures associated with childhood asthma and selected miR-3162-3p for subsequent studies. Since the target proteins and underlying molecular mechanisms of miR-3162-3p in asthma etiopathogenesis are not well characterized, we designed this study to clarify its role. We employed bioinformatics and quantitative PCR methods as a first step to determine the target of miR-3162-3p, and we elucidated β-catenin. Luciferase assays and western blot analysis confirmed β-catenin as a direct target of miR-3162-3p as the 3'-untranslated region of β-catenin mRNA possesses a specific miR-3162-3p pairing site. The correlation between the expression levels of miR-3162-3p and β-catenin is confirmed by quantitative PCR and western blot studies in A549, Beas-2B and H1299 cell lines and OVA-induced asthma mouse model. Of note, upregulation of the endogenous miR-3162-3p level is concomitant with the reduction of β-catenin mRNA and protein expression levels. MiR-3162-3p antagomir treatment antagonizes the endogenous miR-3162-3p and effectively rescues the attenuation of endogenous β-catenin in OVA-induced asthmatic mice, which alleviates airway hyperresponsiveness and ameliorates airway inflammation. Collectively, our findings suggest a novel relationship between miR-3162-3p and β-catenin and clarify their mechanistic role in asthma etiopathogenesis.