A microRNA network dysregulated in asthma controls IL-6 production in bronchial epithelial cells

Mogroside V alleviates inflammation response by modulating miR-21-5P/SPRY1 axis

Mogroside V (MV) is a natural sweetener extracted from the edible plant Siraitia grosvenorii that possesses anti-inflammatory bioactivity. It has been reported that microRNAs (miRNAs) play an important role in the inflammation response suppression by natural agents. However, whether the anti-inflammation effect of mogroside V is related to miRNAs and the underlying mechanism remains unclear. Our study aimed to identify the key miRNAs important for the anti-inflammation effect of MV and reveal its underlying mechanisms. Our results showed that MV effectively alleviated lung inflammation in ovalbumin-induced (OVA-induced) asthmatic mice. miRNA-seq and mRNA-seq combined analysis identified miR-21-5p as an important miRNA for the inflammation inhibition effect of MV and it predicted SPRY1 to be a target gene of miR-21-5p. We found that MV significantly inhibited the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-2 (IL-2), interleukin-6 (IL-6), and nitric oxide (NO), as well as the protein expression of p-P65/P65, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in OVA-induced asthmatic mice and LPS-treated RAW 264.7 cells. Moreover, the release of ROS increased in LPS-stimulated RAW 264.7 cells but was mitigated by MV pretreatment. In the meantime, the expression of miR-21-5p was decreased by MV, leading to an increase in the expression of SPRY1 in RAW 264.7 cells. Furthermore, miR-21-5p overexpression or SPRY1 knockdown reversed MV's protective effect on inflammatory responses. Conversely, miR-21-5p inhibition or SPRY1 overexpression enhanced MV's effect on inflammatory responses in LPS-exposed RAW 264.7 cells. Therefore, the significant protective effect of mogroside V on inflammation response is related to the downregulation of miR-21-5p and upregulation of SPRY1 in vitro and in vivo, MiR-21-5p/SPRY1 may be novel therapeutic targets of MV for anti-inflammation treatment.

Tuning into miRNAs: A comprehensive analysis of their impact on diagnosis, and progression in asthma

Asthma is a diverse inflammatory illness affecting the respiratory passages, leading to breathing challenges, bouts of coughing and wheezing, and, in severe instances, significant deterioration in quality of life. Epigenetic regulation, which involves the control of gene expression through processes such as post-transcriptional modulation of microRNAs (miRNAs), plays a role in the evolution of various asthma subtypes. In immune-mediated diseases, miRNAs play a regulatory role in the behavior of cells that form the airway structure and those responsible for defense mechanisms in the bronchi and lungs. They control various cellular processes such as survival, growth, proliferation, and the production of chemokines and immune mediators. miRNAs possess chemical and biological characteristics that qualify them as suitable biomarkers for diseases. They allow for the categorization of patients to optimize drug selection, thus streamlining clinical management and decreasing both the economic burden and the necessity for critical care related to the disease. This study provides a concise overview of the functions of miRNAs in asthma and elucidates their regulatory effects on the underlying processes of the disease. We provide a detailed account of the present status of miRNAs as biomarkers for categorizing asthma, identifying specific asthma subtypes, and selecting appropriate treatment options.

Prognostic significance of serum miR-18a-5p in severe COVID-19 Egyptian patients

BACKGROUND

The identification of miRNAs as well as characterization of miRNA-mRNA interactions in SARS-CoV-2 infection is important to understand their role in disease pathogenesis. Therefore the aim of the present study was to measure the expression levels of hsa-mir-18a-5p in the sera of severe COVID-19 Egyptian patients admitted to ICU to investigate its roles in the pathogenesis and severity of COVID-19 disease.

METHODS

A total of 180 unvaccinated severe COVID-19 patients were enrolled in our study. Besides the routine laboratory work, the expression level of hsa-mir-18a-5p was done using reverse transcription quantitative real-time PCR (RTqPCR) technique. Also, target genes of hsa-mir-18a-5p were explored by using online bioinformatics databases.

RESULTS

The expression level of hsa-mir-18a-5p decreased in nonsurvival severe COVID-19 patients (0.38 ± 0.26) when compared to the survival ones (0.84 ± 0.23). While as a prognostic tool for the prediction of bad prognosis and mortality among severe COVID-19 patients, our results showed that the serum hsa-mir-18a-5p expression level is a good sensitive and specific marker. By using bioinformatics tools, our results revealed that the decreased hsa-mir-18a-5p expression level may have a crucial role in COVID-19 pathogenesis and severity through decreased immunological responses (interpreted as lymphopenia) or increased inflammation (interpreted as increased serum levels of IL-6, CRP, LDH).

CONCLUSION

Taken together, the decreased expression level of hsa-mir-18a-5p could be a bad prognostic marker and therapeutic overexpression of hsa-mir-18a-5p could be a novel approach in the treatment of COVID-19 disease.

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.

Role of airway epithelial cell miRNAs in asthma

The airway epithelial cells and overlying layer of mucus are the first point of contact for particles entering the lung. The severity of environmental contributions to pulmonary disease initiation, progression, and exacerbation is largely determined by engagement with the airway epithelium. Despite the cellular cross-talk and cargo exchange in the microenvironment, epithelial cells produce miRNAs associated with the regulation of airway features in asthma. In line with this, there is evidence indicating miRNA alterations related to their multifunctional regulation of asthma features in the conducting airways. In this review, we discuss the cellular components and functions of the airway epithelium in asthma, miRNAs derived from epithelial cells in disease pathogenesis, and the cellular exchange of miRNA-bearing cargo in the airways.

The Interaction Network of MicroRNAs with Cytokines and Signaling Pathways in Allergic Asthma

Allergic asthma is a complicated disease that is affected by many factors. Numerous cytokines and signaling pathways are attributed to the cause of asthma symptoms. MicroRNAs (miRNAs) are a group of small non-coding single-stranded RNA molecules that are involved in gene silencing and posttranscriptional regulation of gene expression by targeting mRNAs. In pathological conditions, altered expression of microRNAs differentially regulates cytokines and signaling pathways and therefore, can be the underlying reason for the pathogenesis of allergic asthma. Indeed, microRNAs participate in airway inflammation via inducing airway structural cells and activating immune responses by targeting cytokines and signaling pathways. Thus, to make a complete understanding of allergic asthma, it is necessary to investigate the communication network of microRNAs with cytokines and signaling pathways which is contributed to the pathogenesis of allergic asthma. Here, we shed light on this aspect of asthma pathology by Summarizing our current knowledge of this topic.

Molecular genetics of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severe progressive interstitial lung disease with a prevalence of 2 to 29 per 100,000 of the world’s population. Aging is a significant risk factor for IPF, and the mechanisms of aging (telomere depletion, genomic instability, mitochondrial dysfunction, loss of proteostasis) are involved in the pathogenesis of IPF. The pathogenesis of IPF consists of TGF-β activation, epithelial-mesenchymal transition, and SIRT7 expression decrease. Genetic studies have shown a role of mutations and polymorphisms in mucin genes (MUC5B), in the genes responsible for the integrity of telomeres (TERC, TERC, TINF2, DKC1, RTEL1, PARN), in surfactant-related genes (SFTPC, SFTPCA, SFTPA2, ABCA3, SP-A2), immune system genes (IL1RN, TOLLIP), and haplotypes of HLA genes (DRB1*15:01, DQB1*06:02) in IPF pathogenesis. The investigation of the influence of reversible epigenetic factors on the development of the disease, which can be corrected by targeted therapy, shows promise. Among them, an association of a number of specific microRNAs and long noncoding RNAs was revealed with IPF. Therefore, dysregulation of transposons, which serve as key sources of noncoding RNA and affect mechanisms of aging, may serve as a driver for IPF development. This is due to the fact that pathological activation of transposons leads to violation of the regulation of genes, in the epigenetic control of which microRNA originating from these transposons are involved (due to the complementarity of nucleotide sequences). Analysis of the MDTE database (miRNAs derived from Transposable Elements) allowed the detection of 12 different miRNAs derived in evolution from transposons and associated with IPF (miR-31, miR-302, miR-326, miR-335, miR-340, miR-374, miR-487, miR-493, miR-495, miR-630, miR-708, miR-1343). We described the relationship of transposons with TGF-β, sirtuins and telomeres, dysfunction of which is involved in the pathogenesis of IPF. New data on IPF epigenetic mechanisms can become the basis for improving results of targeted therapy of the disease using noncoding RNAs.

MicroRNAs: A Promising Tool for Asthma Diagnosis and Severity Assessment. A Systematic Review

Micro RNAs (miRNAs) are short, non-coding RNAs (Ribonucleic acids) with regulatory functions that could prove useful as biomarkers for asthma diagnosis and asthma severity-risk stratification. The objective of this systematic review is to identify panels of miRNAs that can be used to support asthma diagnosis and severity-risk assessment. Three databases (Medline, Embase, and SCOPUS) were searched up to 15 September 2020 to identify studies reporting differential expression of specific miRNAs in the tissues of adults and children with asthma. Studies reporting miRNAs associations in animal models that were also studied in humans were included in this review. We identified 75 studies that met our search criteria. Of these, 66 studies reported more than 200 miRNAs that are differentially expressed in asthma patients when compared to non-asthmatic controls. In addition, 16 studies reported 17 miRNAs that are differentially expressed with differences in asthma severity. We were able to construct two panels of miRNAs that are expressed in blood and can serve as core panels to further investigate the practicality and efficiency of using miRNAs as non-invasive biomarkers for asthma diagnosis and severity-risk assessment, respectively.

Effect of Angiotensin-Converting-Enzyme Inhibitor and Angiotensin II Receptor Antagonist Treatment on ACE2 Expression and SARS-CoV-2 Replication in Primary Airway Epithelial Cells

Rationale: SARS-CoV-2 gains entrance to airway epithelial cells (AECs) through binding of the viral spike protein to the angiotensin-converting enzyme 2 (ACE2) on the cell surface. However, ACE2 also converts angiotensin II into angiotensin-(1-7) and counterbalances the renin-angiotensin-aldosterone system, with resultant protective effects in the cardiovascular system. Some data suggest that two common antihypertension medications (angiotensin II receptor antagonists, ARBs; and angiotensin-converting-enzyme inhibitors, ACEIs) may increase ACE2 expression in heart and kidney cells, fueling debate about how these widely used medications may modulate SARS-CoV-2 infectivity and risk of COVID-19. Aim: Determine whether exposure of bronchial AECs to the ARB losartan or the ACEI captopril modulate expression of ACE2 by AECs, SARS CoV2 replication, or expression of proinflammatory cytokines and type I and III interferon (IFN) responses. Methods: Primary bronchial AECs from children and adults (n = 19; Ages 8-75 yrs) were differentiated ex vivo at an air-liquid interface to generate organotypic cultures. Cultures were treated with captopril (1 μM) or losartan (2 μM) with culture media changes starting 72 h before infection with SARS-CoV-2. In a biosafety level 3 (BSL-3) facility, cultures were infected with SARS-CoV-2 isolate USA-WA1/2020 at a multiplicity of infection (MOI) of 0.5. At 96 h following infection, RNA and protein were isolated. SARS-CoV-2 replication in cultures was assessed with quantitative PCR (qPCR). ACE2, IL-6, IL-1B, IFNB1, and IFNL2 expression were assessed by qPCR. Results: Neither captopril nor losartan treatment significantly changed ACE2, IL-6, IL-1B, IFNB1, or IFNL2 expression by AECs as compared to SARS-CoV-2 infected AEC cultures without captopril or losartan treatment. At 96 h following infection, SARS-CoV-2 copy number/ng RNA was not significantly different between untreated AEC cultures, cultures treated with captopril, or cultures treated with losartan. Conclusion: These findings suggest that at the level of the airway epithelium neither the ACEI captopril or ARB losartan significantly modify expression of the SARS-CoV-2 entry factor ACE2, nor does either medication increase replication SARS-CoV-2 replication. This ex vivo data is reassuring and is consistent with evolving clinical data suggesting ACEIs and ARBs do not increase the risk for poor prognosis with COVID-19 and may actually reduce the risk of COVID-19 disease.

Regulation of airway immunity by epithelial miRNAs

The airway epithelium is essential to protect the host from inhaled pathogens and particles. It maintains immune homeostasis and mediates tissue repair after injury. Inflammatory diseases of the airways are associated with failure of epithelial functions, including loss of barrier integrity that results in increased tissue permeability and immune activation; excessive mucus secretion and impaired mucociliary clearance that leads to airflow obstruction and microbial overgrowth; and dysregulation of cellular signals that promotes inflammation and alters tissue structure and airway reactivity. MicroRNAs play crucial roles in mounting appropriate cellular responses to environmental stimuli and preventing disease, using a common machinery and mechanism to regulate gene expression in epithelial cells, immune cells of hematopoietic origin, and other cellular components of the airways. Respiratory diseases are accompanied by dramatic changes in epithelial miRNA expression that drive persistent immune dysregulation. In this review, we discuss responses of the epithelium that promote airway immunopathology, with a focus on miRNAs that contribute to the breakdown of essential epithelial functions. We emphasize the emerging role of miRNAs in regulation of epithelial responses in respiratory health and their value as diagnostic and therapeutic targets.

Atractylodin attenuates the expression of MUC5AC and extracellular matrix in lipopolysaccharide-induced airway inflammation by inhibiting the NF-κB pathway

This study aimed to explore the effects of atractylodin (ATR) on lipopolysaccharide (LPS)-induced inflammatory response in human airway epithelial cells. The cytotoxicity was assessed by CCK-8 assay. The mRNA expression and concentration of interleukin (IL)-6, IL-8, and mucin 5AC (MUC5AC) were measured by qRT-PCR and ELISA, respectively. Western blotting was performed to determine protein expression. We found that LPS stimulation increased the mRNA expression and concentrations of IL-6, IL-8, and MUC5AC, as well as the expression of Col-I and FN in 16HBE cells, but this effect of LPS was attenuated by ATR treatment. Mechanistically, ATR suppressed LPS-induced activation of the NF-κB pathway in 16HBE cells. Moreover, ATR repressed ovalbumin-induced airway inflammation and NF-kB pathway in mice. In conclusion, ATR attenuated the expression of MUC5AC and ECM in LPS-induced airway inflammation by inhibiting the NF-κB pathway.

Zhike pingchuan granules improve bronchial asthma by regulating the IL-6/JAK2/STAT3 pathway

The present study aimed to investigate the effects of zhike pingchuan granules (ZKPC) on bronchial asthma and the underlying mechanism. A bronchial asthma mouse model was established by aerosol inhalation of ovalbumin. The changes in lung pathomorphology were observed by hematoxylin and eosin staining. The levels of IL-1β, TNF-α and IL-6 in bronchoalveolar lavage fluid (BALF) and serum were detected by corresponding ELISA kits. Levels of reactive oxygen species, malondialdehyde and superoxide dismutase in lung tissues were analyzed using corresponding kits. The expression of proteins related to apoptosis and the IL-6/janus kinase 2 (JAK2)/STAT3 pathway was detected by western blot analysis. The results showed that ZKPC significantly restored the dry/wet ratio and alleviated lung pathomorphology of bronchial asthmatic mice. In addition, ZKPC inhibits inflammation, oxidative stress levels and cell apoptosis in bronchial asthmatic mice and also suppressed the IL-6/JAK2/STAT3 pathway. Fedratinib (a JAK2 inhibitor) further strengthened the alleviative effects of ZKPC on bronchial asthma. In conclusion, ZKPC improved bronchial asthma by suppressing the IL-6/JAK2/STAT3 pathway.

Mechanisms and biomarkers of airway epithelial cell damage in asthma: A review

Bronchial asthma is a heterogeneous disease with complex pathological mechanisms representing different phenotypes, including severe asthma. The airway epithelium is a major site of complex pathological changes in severe asthma due, in part, to activation of inflammatory and immune mechanisms in response to noxious agents. Current imaging procedures are unable to accurately measure epithelial and airway remodeling. Damage of airway epithelial cells occurs is linked to specific phenotypes and endotypes which provides an opportunity for the identification of biomarkers reflecting epithelial, and airway, remodeling. Identification of patients with more severe epithelial disruption using biomarkers may also provide personalised therapeutic opportunities and/or markers of successful therapeutic intervention. Here, we review the evidence for ongoing epithelial cell dysregulation in the pathogenesis of asthma, the sentinel role of the airway epithelium and how understanding these molecular mechanisms provides the basis for the identification of candidate biomarkers for asthma prediction, prevention, diagnosis, treatment and monitoring.

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.

A comprehensive analysis of microRNAs as diagnostic biomarkers for asthma

Background:

It is unclear whether microRNAs could be a potential diagnostic biomarker for asthma or not. The objective of this study is to figure out the diagnostic value of microRNAs in asthma.

Methods:

Literature retrieval, screening of publications, specific data extraction, and quality evaluation were conducted according to the standard criteria. Stata 14.0 software was used to analyze the diagnostic value of microRNA for asthma, including the combined sensitivity (Sen), specificity (Spe), the area under the curve (AUC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR).

Results:

A total of 72 studies, containing 4143 cases and 2188 controls, were included for this comprehensive analysis. None of the included publications were rated low in quality. We summarized that, compared with controls, more than 100 miRNAs were reported differently expressed in asthma, although the expression trends were inconsistent. Besides, there were five studies among these 72 articles that applied the diagnostic evaluation of microRNAs in asthma. We found that the pooled Sen, Spe, and AUC for the combination of miR-185-5p, miR-155, let-7a, miR-21, miR-320a, miR-1246, miR-144-5p, and miR-1165-3p in asthma were 0.87 (95%CI: 0.72–0.95), 0.84 (95%CI: 0.74–0.91), and 0.93 (95%CI: 0.89–0.94) individually, and the PLR, NLR, and DOR were 5.5 (95%CI: 3.1–9.7), 0.15 (95%CI: 0.07–0.36), and 35 (95%CI: 10–127) in asthma, respectively. In terms of subgroup analyses, we found that the Sen for these combination miRNAs from serum was higher than that in plasma, while the Spe in plasma worked better than that in serum. Furthermore, compared with children, the combination of above miRNAs from adults had higher Spe and similar Sen.

Conclusions:

From our analysis, the combination of miR-185-5p, miR-155, let-7a, miR-21, miR-320a, miR-1246, miR-144-5p, and miR-1165-3p from peripheral blood could potentially act as a diagnostic biomarker for asthma.

The reviews of this paper are available via the supplemental material section.

LncRNA OIP5‑AS1 aggravates house dust mite‑induced inflammatory responses in human bronchial epithelial cells via the miR‑143‑3p/HMGB1 axis

Bronchial asthma poses a serious threat to human health. Previous studies have documented the role of long non‑coding RNAs (lncRNAs) in asthma. However, the molecular mechanism underlying bronchial asthma remains unclear. The aim of the present study was to evaluate the role of the lncRNA Opa‑interacting protein 5 antisense RNA1 (OIP5‑AS1) in the house dust mite‑induced inflammatory response in human bronchial epithelial cells. BEAS‑2B cells were treated with Dermatophagoides pteronyssinus peptidase 1 (Der p1) to establish an in vitro model of asthma. OIP5‑AS1 expression levels increased in BEAS‑2B cells following Der p1 treatment, while microRNA (miR)‑143‑3p was downregulated. Additionally, the levels of the pro‑inflammatory factors tumor necrosis factor‑α, interleukin (IL)‑6 and IL‑8 were measured, and apoptosis was evaluated following OIP5 silencing. OIP5‑AS1 knockdown reduced the inflammatory response and apoptosis in BEAS‑2B cells. Furthermore, using dual luciferase reporter assays and co‑transfection experiments, it was demonstrated that the function of OIP5‑AS1 was mediated by miR‑143‑3p. miR‑143‑3p overexpression attenuated the Der p1‑induced inflammatory response and apoptosis of BEAS‑2B cells by targeting high mobility group box 1 (HMGB1). In summary, OIP5‑AS1 exacerbated Der p1‑induced inflammation and apoptosis in BEAS‑2B cells by targeting miR‑143‑3p via HMGB1.

PRMT1 Modulates Processing of Asthma-Related Primary MicroRNAs (Pri-miRNAs) into Mature miRNAs in Lung Epithelial Cells

Protein arginine methyltransferase-1 (PRMT1) is an important epigenetic regulator of cell function and contributes to inflammation and remodeling in asthma in a cell type-specific manner. Disease-specific expression patterns of microRNAs (miRNA) are associated with chronic inflammatory lung diseases, including asthma. The de novo synthesis of miRNA depends on the transcription of primary miRNA (pri-miRNA) transcript. This study assessed the role of PRMT1 on pri-miRNA to mature miRNA process in lung epithelial cells. Human airway epithelial cells, BEAS-2B, were transfected with the PRMT1 expression plasmid pcDNA3.1-PRMT1 for 48 h. Expression profiles of miRNA were determined by small RNA deep sequencing. Comparing these miRNAs with datasets of microarrays from five asthma patients (Gene Expression Omnibus dataset), 12 miRNAs were identified that related to PRMT1 overexpression and to asthma. The overexpression or knockdown of PRMT1 modulated the expression of the asthma-related miRNAs and their pri-miRNAs. Coimmunoprecipitation showed that PRMT1 formed a complex with STAT1 or RUNX1 and thus acted as a coactivator, stimulating the transcription of pri-miRNAs. Stimulation with TGF-β1 promoted the interaction of PRMT1 with STAT1 or RUNX1, thereby upregulating the transcription of two miRNAs: let-7i and miR-423. Subsequent chromatin immunoprecipitation assays revealed that the binding of the PRMT1/STAT1 or PRMT1/RUNX1 coactivators to primary let-7i (pri-let-7i) and primary miR (pri-miR) 423 promoter was critical for pri-let-7i and pri-miR-423 transcription. This study describes a novel role of PRMT1 as a coactivator for STAT1 or RUNX1, which is essential for the transcription of pri-let-7i and pri-miR-423 in epithelial cells and might be relevant to epithelium dysfunction in asthma.

The Airway Epithelium-A Central Player in Asthma Pathogenesis

Asthma is a chronic inflammatory airway disease characterized by variable airflow obstruction in response to a wide range of exogenous stimuli. The airway epithelium is the first line of defense and plays an important role in initiating host defense and controlling immune responses. Indeed, increasing evidence indicates a range of abnormalities in various aspects of epithelial barrier function in asthma. A central part of this impairment is a disruption of the airway epithelial layer, allowing inhaled substances to pass more easily into the submucosa where they may interact with immune cells. Furthermore, many of the identified susceptibility genes for asthma are expressed in the airway epithelium. This review focuses on the biology of the airway epithelium in health and its pathobiology in asthma. We will specifically discuss external triggers such as allergens, viruses and alarmins and the effect of type 2 inflammatory responses on airway epithelial function in asthma. We will also discuss epigenetic mechanisms responding to external stimuli on the level of transcriptional and posttranscriptional regulation of gene expression, as well the airway epithelium as a potential treatment target in asthma.

Epithelial cell dysfunction, a major driver of asthma development

Airway epithelial barrier dysfunction is frequently observed in asthma and may have important implications. The physical barrier function of the airway epithelium is tightly interwoven with its immunomodulatory actions, while abnormal epithelial repair responses may contribute to remodelling of the airway wall. We propose that abnormalities in the airway epithelial barrier play a crucial role in the sensitization to allergens and pathogenesis of asthma. Many of the identified susceptibility genes for asthma are expressed in the airway epithelium, supporting the notion that events at the airway epithelial surface are critical for the development of the disease. However, the exact mechanisms by which the expression of epithelial susceptibility genes translates into a functionally altered response to environmental risk factors of asthma are still unknown. Interactions between genetic factors and epigenetic regulatory mechanisms may be crucial for asthma susceptibility. Understanding these mechanisms may lead to identification of novel targets for asthma intervention by targeting the airway epithelium. Moreover, exciting new insights have come from recent studies using single‐cell RNA sequencing (scRNA‐Seq) to study the airway epithelium in asthma. This review focuses on the role of airway epithelial barrier function in the susceptibility to develop asthma and novel insights in the modulation of epithelial cell dysfunction in asthma.

Increased expression of microRNA-155-5p by alveolar type II cells contributes to development of lethal ARDS in H1N1 influenza A virus-infected mice

Alveolar type II (ATII) cells are essential to lung function and a primary site of influenza A virus (IAV) replication. Effects of IAV infection on ATII cell microRNA (miR) expression have not been comprehensively investigated. Infection of C57BL/6 mice with 10,000 or 100 pfu/mouse of IAV A/WSN/33 (H1N1) significantly altered expression of 73 out of 1908 mature murine miRs in ATII cells at 2 days post-infection (d.p.i.) and 253 miRs at 6 d.p.i. miR-155-5p (miR-155) showed the greatest increase in expression within ATII cells at both timepoints and the magnitude of this increase correlated with inoculum size and pulmonary edema severity. Influenza-induced lung injury was attenuated in C57BL/6-congenic miR-155-knockout mice without affecting viral replication. Attenuation of lung injury was dependent on deletion of miR-155 from stromal cells and was recapitulated in ATII cell-specific miR-155-knockout mice. These data suggest that ATII cell miR-155 is a potential therapeutic target for IAV-induced ARDS.

Knockdown of Long Noncoding RNAs of Maternally Expressed 3 Alleviates Hyperoxia-Induced Lung Injury via Inhibiting Thioredoxin-Interacting Protein-Mediated Pyroptosis by Binding to miR-18a

Long-term hyperoxia exposure may cause lung damage with characteristic inflammation. Long noncoding RNA of maternally expressed 3 (MEG3) is up-regulated in lung tissues exposed to hyperoxia; however, the underlying mechanism is unclear. Hyperoxia-induced cells and mouse models were used to study these mechanisms. Molecular assays were used to detect cell viability, cytotoxicity, and expression of miR-18a, MEG3, and inflammatory cytokines. The interaction among MEG3, miR-18a, and thioredoxin-interacting protein (TXNIP) was verified; and pyroptosis-related proteins were analyzed. The in vivo model was established by exposing MEG3 knockdown mice to hyperoxia. Hematoxylin and eosin staining was used to assess pathologic alterations of lung tissues. Hyperoxia suppressed cell viability, induced cell damage, and exacerbated the secretion of IL-1β and IL-18. Hyperoxia inhibited miR-18a, with increased expression of MEG3, TXNIP, and nonobese diabetic-like receptor family pyrin domain containing 3 (NLRP3). MEG3 aggravated TXNIP expression by binding to miR-18a. Knockdown of MEG3 rescued hyperoxia-induced pyroptosis by up-regulating miR-18a. Furthermore, knockdown of MEG3 inhibited NLRP3 inflammasome activity and caspase-1 signaling by miR-18a. In vivo knockdown of MEG3 and overexpression of miR-18a relieved hyperoxia-induced lung injury via restraining NLRP3 inflammasome-mediated pyroptosis, whereas miR-18a inhibition reversed these effects. In conclusion, knockdown of MEG3 inhibits pyroptosis to alleviate hyperoxia lung injury by suppressing NLRP3 inflammasome and caspase-1 signaling via regulating miR-18a-TXNIP axis.

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.

MicroRNAs in Asthma and Respiratory Infections: Identifying Common Pathways

MicroRNAs (miRs) are single-stranded RNAs of 18-25 nucleotides. These molecules regulate gene expression at the post-transcriptional level; several of these are differentially expressed in asthma as well as in viral acute respiratory infections (ARIs), the main triggers of acute asthma exacerbations. In recent years, miRs have been studied in order to discover drug targets as well as biomarkers for diagnosis, disease severity and prognosis. We describe recent findings on miR expression and function in asthma and their role in the regulation of viral ARIs, according to cell tissue specificity and asthma severity. By combining the above information, we identify miRs that may be important in virus-induced asthma exacerbations. This is the first attempt to link miR profiles of asthmatic patients and ARI-induced miRs, addressing the question of whether there might be a specific miR deficit in asthmatic subjects that make them more susceptible and/or reactive to infection.

Divergent Roles of miR-3162-3p in Pulmonary Inflammation in Normal and Asthmatic Mice as well as Antagonism of miR-3162-3p in Asthma Treatment

MicroRNA (miRNA) mimics or antagomirs hold great promise for asthma treatment compared with glucocorticoids as mainstay therapy for asthma. But the role of miRNA in regulating asthmatic inflammation is largely unclear. We previously reported that miR-3162-3p in the peripheral blood of children with asthma was obviously upregulated compared to that in healthy children. This study aimed to elucidate the role of miR-3162-3p in pulmonary inflammation in normal and asthmatic mice as well as preliminarily explore the potential of miR-3162-3p antagomir in asthma treatment. A noninvasive whole-body plethysmograph measured airway responsiveness. Both qRT-PCR and Western blot were used to detect the expression of miRNA, mRNA, or protein. Cells in bronchoalveolar lavage fluid were counted by platelet counting and Wright's staining. Inflammatory infiltration and mucus secretion were identified by hematoxylin and eosin and periodic acid-Schiff  staining, respectively. Cytokines in the lungs were detected by ELISA. The miR-3162-3p mimic intraperitoneally administered to normal mice decreased β-catenin levels in the lungs without obviously altering the lung histology and cytokine levels. Antagonizing miR-3162-3p in ovalbumin-induced asthmatic mice effectively alleviated the typical features of asthma, such as airway hyper-responsiveness, airway inflammation, and Th1/Th2 cytokine imbalance, and concomitantly rescued the total and active β-catenin expression. Collectively, we discovered divergent roles of miR-3162-3p in lung inflammation between normal and asthmatic mice. The anti-inflammatory effects of the miR-3162-3p antagomir were comparable to those of glucocorticoid treatment. Our study helped in understanding the contribution of miRNAs to the pathogenesis of asthma.

MiR-20a-5p suppressed TGF-β1-triggered apoptosis of human bronchial epithelial BEAS-2B cells by targeting STAT3

Apoptosis of bronchial epithelial cells contributes to lung diseases, including asthma. Although miR-20a-5p is reportedly downregulated in the bronchial epithelia of asthmatic patients, its function and mechanism still need to be explored. Here, we explored how miR-20a-5p affects human bronchial epithelial cells stimulated with transforming growth factor (TGF)-β₁. Using qRT-PCR, we observed downregulated miR-20a-5p levels in these cells. After transfecting miR-20a-5p mimics or inhibitors into human bronchial epithelium BEAS-2B cells, a Cell Counting Kit-8 assay and flow cytometry analysis showed that the mimics mitigated suppression of cell viability and acceleration of apoptosis that was triggered by TGF-β₁, whereas the inhibitors exerted the opposite effects. TGF-β₁ induced a decrease in expression of Bcl-2 and an increase in expression of Bax, both of which were inhibited by miR-20a-5p mimics and further enhanced by miR-20a-5p inhibitors. Further study verified that miR-20a-5p targeted the signal transducer and activator of transcription 3 (STAT3) and the STAT3 level was inversely related to the miR-20a-5p level. Furthermore, STAT3 overexpression partly counteracted the miR-20a-5p-induced anti-apoptotic effect in TGF-β1-treated BEAS-2B cells. In summary, this study suggested that miR-20a-5p restrained apoptosis in TGF-β1-stimulated BEAS-2B cells by targeting STAT3. MiR-20a-5p thus may be a novel therapeutic target for asthma treatment.

Small RNA Species and microRNA Profiles are Altered in Severe Asthma Nanovesicles from Broncho Alveolar Lavage and Associate with Impaired Lung Function and Inflammation

MicroRNAs are known to regulate important pathways in asthma pathology including the IL-6 and IFN pathways. MicroRNAs have been found not only within cells but also within extracellular vesicles such as exosomes. In this study, we particularly focused on microRNA cargo of nanovesicles in bronchoalveolar lavage of severe asthmatic patients. We extracted nanovesicle RNA using a serial filtration method. RNA content was analyzed with small RNA sequencing and mapped to pathways affected using WebGestalt 2017 Software. We report that severe asthma patients have deficient loading of microRNAs into their airway luminal nanovesicles and an altered profile of small RNA nanovesicle content (i.e., ribosomal RNA and broken transcripts, etc.). This decrease in microRNA cargo is predicted to increase the expression of genes by promoting inflammation and remodeling. Consistently, a network of microRNAs was associated with decreased FEV₁ and increased eosinophilic and neutrophilic inflammation in severe asthma. MicroRNAs in airway nanovesicles may, thus, be valid biomarkers to define abnormal biological disease processes in severe asthma and monitor the impact of interventional therapies.

YRNAs overexpression and potential implications in allergy

Background

Small non-coding RNAs (snRNAs) develop important functions related to epigenetic regulation. YRNAs are snRNAs involved in the initiation of DNA replication and RNA stability that regulate gene expression. They have been related to autoimmune, cancer and inflammatory diseases but never before to allergy. In this work we described for the first time in allergic patients the differential expression profile of YRNAs, their regulatory mechanisms and their potential as new diagnostic and therapeutic targets.

Methods

From a previous whole RNAseq study in B cells of allergic patients, differential expression profiles of coding and non-coding transcripts were obtained. To select the most differentially expressed non coding transcripts, fold change and p-values were analyzed. A validation of the expression differences detected was developed in an independent cohort of 304 individuals, 208 allergic patients and 96 controls by using qPCR. Potential binding and retrotransponibility capacity were characterized by in silico structural analysis. Using a novel bioinformatics approach, RNA targets identification, functional enrichment and network analyses were performed.

Results

We found that almost 70% of overexpressed non-coding transcripts in allergic patients corresponded to YRNAs. From the three more differentially overexpressed candidates, increased expression was independently confirmed in the peripheral blood of allergic patients. Structural analysis suggested a protein binding capacity decrease and an increase in retrotransponibility. Studies of RNA targets allowed the identification of sequences related to the immune mechanisms underlying allergy.

Conclusions

Overexpression of YRNAs is observed for the first time in allergic patients. Structural and functional information points to their implication on regulatory mechanisms of the disease.

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.

A Review of Macrophage MicroRNAs' Role in Human Asthma

There is an imbalance in asthma between classically activated macrophages (M1 cells) and alternatively activated macrophages (M2 cells) in favor of the latter. MicroRNAs (miRNAs) play a critical role in regulating macrophage proliferation and differentiation and control the balance of M1 and M2 macrophage polarization, thereby controlling immune responses. Here we review the current published data concerning miRNAs with known correlation to a specific human macrophage phenotype and polarization, and their association with adult asthma. MiRNA-targeted therapy is still in the initial stages, but clinical trials are under recruitment or currently running for some miRNAs in other diseases. Regulating miRNA expression via their upregulation or downregulation could show potential as a novel therapy for improving treatment efficacy in asthma.

microRNA-23a contributes to asthma by targeting BCL2 in airway epithelial cells and CXCL12 in fibroblasts

The deregulated cross-talk between airway epithelial cells with subepithelial fibroblasts during inflammation drives the pathogenesis of asthma. Bioinformatics analysis and luciferase activity assay suggested that B cell lymphoma-2 (BCL2) and CXC ligand 12 (CXCL12) are potential targets of miR-23a. The aim of this study was to elucidate the effect of microRNA-23a (miR-23a) on BCL2, and CXCL12 in asthma. In E3 rats, miR-23a was upregulated in lung tissues after antigen-induced pulmonary inflammation during acute and chronic inflammation. Immunohistochemistry showed downregulation of BCL2 in the epithelium and of CXCL12 in subepithelial fibroblasts and smooth muscle cells. Treatment of isolated cells with miR-23a mimic or inhibitor modified the expression of BCL2 and of CXCL12 in the expected cell type-specific manner. Moreover, in epithelial cells, interleukin-4 upregulated miR-23a expression and thereby decreased the expression of BCL2, while increasing the caspase-3 expression, which was followed by apoptosis. In fibroblasts, the expression of miR-23a was increased by thymic stromal lymphopoietin (TSLP). Consequently, the CXCL12 expression was abrogated. The phosphorylation of CREB was also downregulated by TSLP through the action of miR-23a. This study describes a novel mechanism, where miR-23a is an important cell type-specific regulator for asthma-associated airway wall remodeling parameter. Thus, miR-23a may present a potential new target for the therapy of asthma.

Respiratory syncytial virus promoted the differentiation of Th17 cells in airway microenvironment through activation of Notch-1/Delta3

BACKGROUND

Respiratory syncytial virus (RSV) infection is associated with serious lung disease in infants and immunocompromised individuals and is linked to development of asthma. Infection of RSV has been shown to induce Th lymphocyte differentiation. The present study was designed to determine the effects of RSV on the expression of Notch-1 and the related mechanisms on subsequent differentiation of Th lymphocytes.

METHODS

A RSV-infected animal model was established and investigated at 7, 28 and 60 days post infection. Real-time qPCR and Western blot were used to observe the expression levels of Notch-1 in CD4+ T cells and its five ligands in lung tissues. The methylation levels of CpG islands in autoimmune regulator (AIRE) and Notch-1 promoters were analysed by time-of-flight mass spectrometry. The differentiation of Th lymphocytes was assayed by real-time qPCR. The distribution of JAG1 and DLL3 in the lung tissues were assayed by immunohistochemistry. The correlation between Th17 and DLL3 was analysed by simple correlation.

RESULTS

The results showed that RSV promoted the expression and de-methylation of Notch-1 promoters in CD4+ T cells. Moreover, RSV infection promoted Th1 differentiation at day 7 and day 28; Th17 differentiation at day 7, day 28 and day 60; Th2 differentiation at day 28 and day 60. At the same time, RSV infection promoted the expression of JAG1 and DLL3. Activation of Notch-1/ DLL 3 in lungs may be associated with the differentiation of Th17 lymphocytes.

CONCLUSIONS

Our data showed that activation of RSV stimulated the differentiation of Th17 in airway microenvironment through activation Notch-1/DLL3, which may be associated with the occurrence and development of RSV-induced asthma.

MicroRNA-744 Inhibits Proliferation of Bronchial Epithelial Cells by Regulating Smad3 Pathway via Targeting Transforming Growth Factor-β1 (TGF-β1) in Severe Asthma

BACKGROUND Bronchial epithelial cells proliferation plays a pivotal role in airway remodeling in children with severe asthma. MicroRNAs (miRNAs) have gained great attention for many diseases, including asthma. The purpose of this study was to explore the mechanisms that underlie miR-744 modulating bronchial epithelial cells proliferation in severe asthma in children. MATERIAL AND METHODS Bronchial epithelial cells were isolated from bronchial biopsies of normal controls and asthmatic subjects. miR-744 and transforming growth factor-ß1 (TGF-ß1) expressions were measured by quantitative reverse transcription PCR (qRT-PCR). Proliferating cell nuclear antigen (PCNA), phosphorylation or total of mothers against decapentaplegic homolog3 (Smad3) and production of Smad anchor for receptor activation (SARA) were measured via Western blot analysis. A link between miR-744 and TGF-ß1 was probed by luciferase activity and RNA immunoprecipitation. Cell proliferation was evaluated using the Cell Proliferation Assay Kit. RESULTS Severe asthma showed a significantly elevated cell proliferation rate and reduced abundance of miR-744, which in turn inhibited cell proliferation of bronchial epithelial cells. In particular, TGF-ß1 might be a candidate target of miR-744, and enrichment of miR-744 lowered the expression of TGF-ß1 at mRNA and protein levels. Indeed, overexpression of miR-744 lowered the proliferation rate of bronchial epithelial cells via driving TGF-ß1. Moreover, addition of miR-744 limited phosphorylation of Smad3 but reversed SARA protein abundance by regulating TGF-ß1. CONCLUSIONS The presence of miR-744 repressed bronchial epithelial cells proliferation through mediating the Smad3 pathway by modulating TGF-ß1, providing a promising therapeutic approach for epithelial function in severe asthma.

hsa-miR-20a-5p attenuates allergic inflammation in HMC-1 cells by targeting HDAC4

micro-RNAs (miRNAs) are non-coding RNAs which play important role in human diseases. Dysregulated miRNAs have been identified in asthma patient while their precise roles in asthma are not well elucidated. We compared the expression level of total 11 miRNAs between PMA/A23187-treated and control HMC-1 mast cells. We determined the effect of miR-20a on inflammation by overexpressing miR-20a mimic or its antagonist. We further predicted histone deacetylase 4 (HDAC4) as potential target of miR-20a and explored the effects of miR-20a on HDAC4 expression and histone modification. miR-20a was down-regulated in PMA/A23187-treated HMC-1 cells. miR-20a inhibited expression of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β) and Interferon gamma (IFN-γ) while promoted Interleukin 10 (IL-10) production. miR-20a targeted HDAC4 and suppressed its expression, which contributed to epigenetically regulation of IL-10 expression by miR-20a. hsa-miR-20a-5p attenuates allergic inflammation in HMC-1 cells by targeting HDAC4.

miR‑625‑5p suppresses inflammatory responses by targeting AKT2 in human bronchial epithelial cells

Asthma is a common chronic inflammatory airway disease; however, whether microRNAs (miRs) could be used in the treatment of asthma remains unclear. The aim of the present study was to investigate the role of miR‑625‑5p in the inflammatory response of human bronchial epithelial cells (HBECs). Inflammation in the HBEC line, 16HBEC, was induced using different concentrations of lipopolysaccharide (LPS), which demonstrated that 1 µg/ml LPS was an appropriate concentration for further experiments. The association between protein kinase B2 (AKT2) and miR‑625‑5p was verified using a luciferase reporter assay. LPS was added to 16HBECs following the administration of miR‑625‑5p mimics or miR‑625‑5p inhibitors, and cells with silenced or overexpressed AKT2 levels. miR‑625‑5p was expressed at a high level in LPS‑activated 16HBECs. Overexpression of miR‑625‑5p inhibited interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α secretion in 16HBECs. Inhibition of miR‑625‑5p enhanced LPS‑induced IL‑6 and TNF‑α secretion. miR‑625‑5p negatively regulated the expression of AKT2 in 16HBECs. A dual‑luciferase reporter assay system confirmed that miR‑625‑5p directly targeted the 3'untranslated region of AKT2. Transfection with a small interfering RNA against AKT2 inhibited inhibitor of κB phosphorylation. In brief, miR‑625‑5p may protect LPS‑induced HBECs by targeting AKT2 and inhibiting the nuclear factor‑κB signaling pathway. Therefore, miR‑625‑5p may function as an inhibitor of asthma airway inflammation in HBECs by targeting AKT2.

Changes in circulating microRNA-126 levels are associated with immune imbalance in children with acute asthma

Regulation of the immune response in asthma is complex. MicroRNA-126 (miR-126) expression has been implicated in this response, so we sought to determine the clinical significance of miR-126 measured in the peripheral blood. A total of 80 children with acute asthma were selected to participate in the study and were compared to 80 healthy children. The relative circulating miR-126 levels, interleukin (IL)-4 levels, and the Th17 cell percentage in the peripheral blood of children in the case group were significantly higher than those in the control group, while the interferon (IFN)-γ levels and the CD4⁺CD25⁺Treg cell percentage were significantly lower than those in the control group. Along with the aggravation of the disease, the relative levels of miR-126 and IL-4 and the percentage of Th17 cells increased gradually, while the IFN-γ levels and the CD4⁺CD25⁺Treg cell percentage decreased. The relative level of miR-126 in the peripheral blood of children with asthma was positively correlated with IL-4 and the Th17 cell percentage and was negatively correlated with IFN-γ levels, CD4⁺CD25⁺Treg cell percentage and lung function indicators. The relative level of miR-126 was correlated with the Th17 cell percentage in the peripheral blood, forced vital capacity (FVC), and forced expiratory flow (FEF)_75% of the children with asthma. The relative levels of miR-126 and IL-4 and the Th17 cell percentage were positively correlated with the severity of the asthma, while IFN-γ levels and the CD4⁺CD25⁺Treg cell percentage were negatively correlated with the severity of the asthma. CD4⁺CD25⁺Treg cell percentage and relative miR-126 levels were of the most predictive value in the diagnosis of asthma. Our findings show that the overexpression of miR-126 in acute asthma is correlated with signs of immune imbalance and is predictive of the severity of the disease, suggesting that it could be used as a potential serological marker for asthma diagnosis and evaluation.

Human leukocyte antigen-G 3' untranslated region polymorphisms are associated with asthma severity

Asthma is a genetically complex chronic inflammatory airway disorder, and according to disease pathogenesis, clinical manifestations may vary according to asthma severity. A gene region close to the human leukocyte antigen-G (HLA-G) gene was identified as an independent susceptibility marker for asthma. Considering that the HLA-G immune checkpoint molecule may modulate inflammation, we evaluated the diversity of the HLA-G 3' untranslated region (3'UTR) in asthmatic patients stratified according to disease severity. We evaluate the entire HLA-G 3'UTR segment in 115 Brazilian patients stratified into mild (n=29), moderate (n=21) and severe asthmatics (n=65), and in 116 healthy individuals. HLA-G 3'UTR typing was performed using Sanger sequencing. The multiple comparisons among patients stratified according to disease severity revealed several associations; however, after Bonferroni's correction, the following results remained significant: i) the +3010C and +3142G alleles were overrepresented in mild asthma patients when compared to controls; ii) the +3010G and +3142C alleles were overrepresented in severe asthma patients in comparison to patients with mild asthma. In conclusion, the +3010C/G and +3142C/G HLA-G 3'UTR variation sites were differentially associated according to asthma severity.

Asthma MicroRNA Regulome Development Using Validated miRNA-Target Interaction Visualization

Asthma is a common multifactorial complex disease caused by an interaction of genetic and environmental factors. There are no robust biomarkers or molecular diagnostics for asthma or its detailed phenotypic stratification in the clinic. Regulatory and epigenomic factors are priority candidates for asthma biomarker discovery and translational research because this common disease emerges in association with host/environment interactions. In this context, epigenomic molecular events such as microRNA (miRNA) silencing affect asthma susceptibility and severity. We report here an analysis of the miRNAs in the literature, their targets associated with asthma, and present the findings organized as an miRNA-target network, an miRNA regulome of asthma. The miRNA-target interactions in asthma were extracted from the PubMed and the Web of Science databases, while the miRNA-target network was visualized with the Cytoscape tool. Genomic locations of miRNA and target genes were displayed using the Ensembl Whole Genome tool. We cataloged miRNAs associated with asthma and their experimentally validated targets, retrieving 48 miRNAs associated with asthma, and 54 experimentally validated miRNA targets. Four central molecules involved in 34.5% of all interactions were identified in the network. The miRNA-target pairs were constructed as an asthma-associated miRNA-target regulatory network. The network revealed subnetworks pointing toward potential asthma biomarker candidates. The asthma miRNA regulome reported here offers a strong foundation for future translational research and systems medicine applications for asthma diagnostic and therapeutic innovation. Developed protocol for constructing miRNA regulome could now be used for biomarker development in multifactorial diseases.

Influenza A virus infection dysregulates the expression of microRNA-22 and its targets; CD147 and HDAC4, in epithelium of asthmatics

Background

Specific microRNAs (miRNAs) play essential roles in airway remodeling in asthma. Infection with influenza A virus (IAV) may also magnify pre-existing airway remodeling leading to asthma exacerbation. However, these events remain to be fully defined. We investigated the expression of miRNAs with diverse functions including proliferation (miR-20a), differentiation (miR-22) or innate/adaptive immune responses (miR-132) in primary bronchial epithelial cells (pBECs) of asthmatics following infection with the H1N1 strain of IAV.

Methods

pBECs from subjects (n = 5) with severe asthma and non-asthmatics were cultured as submerged monolayers or at the air-liquid-interface (ALI) conditions and incubated with IAV H1N1 (MOI 5) for up to 24 h. Isolated miRNAs were subjected to Taqman miRNAs assays. We confirmed miRNA targets using a specific mimic and antagomir. Taqman mRNAs assays and immunoblotting were used to assess expression of target genes and proteins, respectively.

Results

At baseline, these miRNAs were expressed at the same level in pBECs of asthmatics and non-asthmatics. After 24 h of infection, miR-22 expression increased significantly which was associated with the suppression of CD147 mRNA and HDAC4 mRNA and protein expression in pBECs from non-asthmatics, cultured in ALI. In contrast, miR-22 remained unchanged while CD147 expression increased and HDAC4 remained unaffected in cells from asthmatics. IAV H1N1 mediated increases in SP1 and c-Myc transcription factors may underpin the induction of CD147 in asthmatics.

Conclusion

The different profile of miR-22 expression in differentiated epithelial cells from non-asthmatics may indicate a self-defense mechanism against aberrant epithelial responses through suppressing CD147 and HDAC4, which is compromised in epithelial cells of asthmatics.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0851-7) contains supplementary material, which is available to authorized users.

Precision Medicine in Targeted Therapies for Severe Asthma: Is There Any Place for "Omics" Technology?

According to the current guidelines, severe asthma still represents a controversial topic in terms of definition and management. The introduction of novel biological therapies as a treatment option for severe asthmatic patients paved the way to a personalized approach, which aims at matching the appropriate therapy with the different asthma phenotypes. Traditional asthma phenotypes have been decomposing by an increasing number of asthma subclasses based on functional and physiopathological mechanisms. This is possible thanks to the development and application of different omics technologies. The new asthma classification patterns, particularly concerning severe asthma, include an increasing number of endotypes that have been identified using new omics technologies. The identification of endotypes provides new opportunities for the management of asthma symptoms, but this implies that biological therapies which target inflammatory mediators in the frame of specific patterns of inflammation should be developed. However, the pathway leading to a precision approach in asthma treatment is still at its beginning. The aim of this review is providing a synthetic overview of the current asthma management, with a particular focus on severe asthma, in the light of phenotype and endotype approach, and summarizing the current knowledge about "omics" science and their therapeutic relevance in the field of bronchial asthma.

Association of epilepsy and asthma: a population-based retrospective cohort study

Background

Epidemiologic data supporting the epilepsy–asthma association are insufficient. Therefore, we examined this association in this study.

Methods

By using claims data from the National Health Insurance Research Database (Taiwan), we executed a retrospective cohort analysis. Analysis 1 entailed comparing 150,827 patients diagnosed as having incident asthma during 1996–2013 with disease-free controls who were selected randomly during the same period, frequency matched in terms of age and sex. Similarly, analysis 2 entailed comparing 25,274 patients newly diagnosed as having epilepsy with sex- and age-matched controls who were selected randomly. At the end of 2013, we evaluated in analysis 1 the epilepsy incidence and risk and evaluated in analysis 2 the asthma incidence and risk. We applied Kaplan–Meier analysis to derive plots of the proportion of asthma-free seizures.

Results

In analysis 1, the asthma group exhibited a higher epilepsy incidence than did the control group (3.05 versus 2.26 per 1,000 person-years; adjusted hazard ratio: 1.39, 95% CI [1.33–1.45]). We also noted a greater risk of subsequent epilepsy in women and girls. In analysis 2, we determined that the asthma incidence between the control and epilepsy groups did not differ significantly; however, some age subgroups including children and individuals in their 30s had an increased risk. A negative association was found in adolescents. The Kaplan–Meier analysis revealed epilepsy to be positively associated with subsequent onset of asthma within seven years of epilepsy diagnosis.

Discussion

Asthma may be associated with high epilepsy risk, and epilepsy may be associated with high asthma risk among children and individuals in their 30s. Nevertheless, people with epilepsy in other age subgroups should be aware of the possibility of developing asthma within seven years of epilepsy diagnosis.

Genome-Wide Posttranscriptional Dysregulation by MicroRNAs in Human Asthma as Revealed by Frac-seq

MicroRNAs are small noncoding RNAs that inhibit gene expression posttranscriptionally, implicated in virtually all biological processes. Although the effect of individual microRNAs is generally studied, the genome-wide role of multiple microRNAs is less investigated. We assessed paired genome-wide expression of microRNAs with total (cytoplasmic) and translational (polyribosome-bound) mRNA levels employing subcellular fractionation and RNA sequencing (Frac-seq) in human primary bronchoepithelium from healthy controls and severe asthmatics. Severe asthma is a chronic inflammatory disease of the airways characterized by poor response to therapy. We found genes (i.e., isoforms of a gene) and mRNA isoforms differentially expressed in asthma, with novel inflammatory and structural pathophysiological mechanisms related to bronchoepithelium disclosed solely by polyribosome-bound mRNAs (e.g., IL1A and LTB genes or ITGA6 and ITGA2 alternatively spliced isoforms). Gene expression (i.e., isoforms of a gene) and mRNA expression analysis revealed different molecular candidates and biological pathways, with differentially expressed polyribosome-bound and total mRNAs also showing little overlap. We reveal a hub of six dysregulated microRNAs accounting for ∼90% of all microRNA targeting, displaying preference for polyribosome-bound mRNAs. Transfection of this hub in bronchial epithelial cells from healthy donors mimicked asthma characteristics. Our work demonstrates extensive posttranscriptional gene dysregulation in human asthma, in which microRNAs play a central role, illustrating the feasibility and importance of assessing posttranscriptional gene expression when investigating human disease.

Effects of microRNA-19b on airway remodeling, airway inflammation and degree of oxidative stress by targeting TSLP through the Stat3 signaling pathway in a mouse model of asthma

This study explored the effects of microRNA-19b (miR-19b) on airway remodeling, airway inflammation, and degree of oxidative stress in a mouse model of asthma. Bioinformatics analyses and dual luciferase reporter gene assays revealed that thymic stromal lymphopoietin (TSLP) is a direct target of miR-19b. An asthma model was established via ovalbumin (OVA) sensitization and challenge in 72 female BALB/c mice. Mice were then assigned to saline, OVA-sensitized, saline+miR-19b mimics, saline+anti-TSLP, OVA-sensitized+miR-19b mimics, OVA-sensitized+mimics scramble, OVA-sensitized+anti-TSLP, and OVA-sensitized+IgG2a groups. Pathological morphology changes were detected through hematoxylin/eosin, Masson, and periodic acid-Schiff staining. miR-19b was downregulated while TSLP and Stat3 were upregulated in the OVA-sensitized group compared with the saline group. Bronchoalveolar lavage fluid samples from OVA-sensitized mice showed increased total protein, IL-4, IL-5 and IL-6 levels, numbers of inflammatory cells, eosinophils, neutrophils, mononuclear macrophages and lymphocytes, and eosinophil% compared to controls. Lung tissues from sensitized mice exhibited decreased superoxide dismutase activity and increased methane dicarboxylic aldehyde levels. The effects of OVA sensitization were reversed in the OVA-sensitized+miR-19b mimics and OVA-sensitized+anti-TSLP groups. These findings suggest miR-19b reduces airway remodeling, airway inflammation, and degree of oxidative stress by inhibiting Stat3 signaling through TSLP downregulation in a mouse asthma model.

Casticin alleviates lipopolysaccharide-induced inflammatory responses and expression of mucus and extracellular matrix in human airway epithelial cells through Nrf2/Keap1 and NF-κB pathways

Asthma is one of the most common chronic inflammatory diseases of childhood, characterized by airway inflammation, mucus hypersecretion, and accumulation of extracellular matrix proteins. Casticin is an active compound that possesses broad biological activities including anti-inflammatory effect. However, the effect of casticin on asthma remains unknown. The aim of the present study was to evaluate the effect and mechanism of casticin on inflammatory responses and expression of mucus and extracellular matrix in human airway epithelial cells. The results showed that lipopolysaccharide induced the mRNA and protein levels of IL-6, IL-8, MUC5AC, collagen type I, and fibronectin in 16-HBE cells, whereas casticin treatment significantly inhibited the induction of lipopolysaccharide. Casticin induced Nrf2/Keap1 and inhibited nuclear factor κB pathways in 16-HBE cells. Knockdown of Nrf2 attenuated the effect of casticin on production of IL-6 and IL-8, expression of MUC5AC, collagen type I, and fibronectin in 16-HBE cells. In conclusion, the results indicated that casticin might be a novel therapeutic strategy for the treatment of asthma.

Differential Expression of Serum MicroRNAs Supports CD4⁺ T Cell Differentiation into Th2/Th17 Cells in Severe Equine Asthma

MicroRNAs (miRNAs) regulate post-transcriptional gene expression and may be exported from cells via exosomes or in partnership with RNA-binding proteins. MiRNAs in body fluids can act in a hormone-like manner and play important roles in disease initiation and progression. Hence, miRNAs are promising candidates as biomarkers. To identify serum miRNA biomarkers in the equine model of asthma we investigated small RNA derived from the serum of 34 control and 37 asthmatic horses. These samples were used for next generation sequencing, novel miRNA identification and differential miRNA expression analysis. We identified 11 significantly differentially expressed miRNAs between case and control horses: eca-miR-128, eca-miR-744, eca-miR-197, eca-miR-103, eca-miR-107a, eca-miR-30d, eca-miR-140-3p, eca-miR-7, eca-miR-361-3p, eca-miR-148b-3p and eca-miR-215. Pathway enrichment using experimentally validated target genes of the human homologous miRNAs showed a significant enrichment in the regulation of epithelial-to-mesenchymal transition (key player in airway remodeling in asthma) and the phosphatidylinositol (3,4,5)-triphosphate (PIP3) signaling pathway (modulator of CD4⁺ T cell maturation and function). Downregulated miR-128 and miR-744 supports a Th2/Th17 type immune response in severe equine 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.

Identification of novel genetic regulations associated with airway epithelial homeostasis using next-generation sequencing data and bioinformatics approaches

Airway epithelial cells play important roles in airway remodeling. Understanding gene regulations in airway epithelial homeostasis may provide new insights into pathogenesis and treatment of asthma. This study aimed to combine gene expression (GE) microarray, next generation sequencing (NGS), and bioinformatics to explore genetic regulations associated with airway epithelial homeostasis. We analyzed expression profiles of mRNAs (GE microarray) and microRNAs (NGS) in normal and asthmatic bronchial epithelial cells, and identified 9 genes with potential microRNA-mRNA interactions. Of these 9 dysregulated genes, downregulation of MEF2C and MDGA1 were validated in a representative microarray (GSE43696) from the gene expression omnibus (GEO) database. Our findings suggested that upregulated mir-203a may repress MEF2C, a transcription factor, leading to decreased cellular proliferation. In addition, upregulated mir-3065-3p may repress MDGA1, a cell membrane anchor protein, resulting in suppression of cell-cell adhesion. We also found that KCNJ2, a potassium channel, was downregulated in severe asthma and may promote epithelial cell apoptosis. We proposed that aberrant regulations of mir-203a-MEF2C and mir-3065-3p-MDGA1, as well as downregulation of KCNJ2, play important roles in airway epithelial homeostasis in asthma. These findings provide new perspectives on diagnostic or therapeutic strategies targeting bronchial epithelium for asthma. The approach in this study also provides a new aspect of studying 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.

Nasal airway epithelial cell IL-6 and FKBP51 gene expression and steroid sensitivity in asthmatic children

Background

Many asthmatic patients exhibit uncontrolled asthma despite high-dose inhaled corticosteroids (ICS). Airway epithelial cells (AEC) have distinct activation profiles that can influence ICS response.

Objectives

A pilot study to identify gene expression markers of AEC dysfunction and markers of corticosteroid sensitivity in asthmatic and non-asthmatic control children, for comparison with published reports in adults.

Methods

AEC were obtained by nasal brushings and primary submerged cultures, and incubated in control conditions or in the presence of 10 ng/ml TNFalpha, 10^-8M dexamethasone, or both. RT-PCR-based expression of FKBP51 (a steroid hormone receptor signalling regulator), NF-kB, IL-6, LIF (an IL-6 family neurotrophic cytokine), serpinB2 (which inhibits plasminogen activation and promotes fibrin deposition) and porin (a marker of mitochondrial mass) were determined.

Results

6 patients without asthma (median age 11yr; min-max: 7–13), 8 with controlled asthma (11yr, 7–13; median daily fluticasone dose = 100 μg), and 4 with uncontrolled asthma (12yr, 7–14; 1000 μg fluticasone daily) were included. Baseline expression of LIF mRNA was significantly increased in uncontrolled vs controlled asthmatic children. TNFalpha significantly increased LIF expression in uncontrolled asthma. A similar trend was observed regarding IL-6. Dexamethasone significantly upregulated FKBP51 expression in all groups but the response was blunted in asthmatic children. No significant upregulation was identified regarding NF-kB, serpinB2 and porin.

Conclusion

LIF and FKBP51 expression in epithelial cells were the most interesting markers of AEC dysfunction/response to corticosteroid treatment.

Constitutive high expression of protein arginine methyltransferase 1 in asthmatic airway smooth muscle cells is caused by reduced microRNA-19a expression and leads to enhanced remodeling

BACKGROUND

In asthma remodeling airway smooth muscle cells (ASMCs) contribute to airway wall thickness through increased proliferation, migration, and extracellular matrix deposition. Previously, we described that protein arginine methyltransferase 1 (PRMT1) participates in airway remodeling in pulmonary inflammation in E3 rats.

OBJECTIVE

We sought to define the asthma-specific regulatory mechanism of PRMT1 in human ASMCs.

METHODS

ASMCs from healthy subjects and asthmatic patients were activated with platelet-derived growth factor (PDGF)-BB. PRMT1 was localized by means of immunohistochemistry in human lung tissue sections and by means of immunofluorescence in isolated ASMCs. PRMT1 activity was suppressed by the pan-PRMT inhibitor AMI-1, signal transducer and activator of transcription 1 (STAT1) was suppressed by small interfering RNA, and extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinase (MAPK) was suppressed by PD98059. MicroRNAs (miRs) were assessed by using real-time quantitative PCR and regulated by miR mimics or inhibitors.

RESULTS

PRMT1 expression was significantly increased in lung tissue sections and in isolated ASMCs of patients with severe asthma. PDGF-BB significantly increased PRMT1 expression through ERK1/2 MAPK and STAT1 signaling in control ASMCs, whereas in ASMCs from asthmatic patients, these proteins were constitutively expressed. ASMCs from asthmatic patients had reduced miR-19a expression, causing upregulation of ERK1/2 MAPK, STAT1, and PRMT1. Inhibition of PRMT1 abrogated collagen type I and fibronectin deposition, cell proliferation, and migration of ASMCs from asthmatic patients.

CONCLUSIONS

PRMT1 is a central regulator of tissue remodeling in ASMCs from asthmatic patients through the pathway: PDGF-BB-miR-19a-ERK1/2 MAPK and STAT1. Low miR-19a expression in ASMCs from asthmatic patients is the key event that results in constitutive increased PRMT1 expression and remodeling. Therefore PRMT1 is an attractive target to limit airway wall remodeling in asthmatic patients.

LPS Cooperates with Poly-L-Arginine to Promote IL-6 and IL-8 Release via the JNK Signaling Pathway in NCI-H292 Cells

Objective. Herein, we aimed to study the mechanism whereby poly-L-arginine (PLA) and lipopolysaccharide (LPS) can synergistically induce the release of interleukin-6 (IL-6) and IL-8 in NCI-H292 cells. Methods. NCI-H292 cells were divided into control, PLA, LPS, and PLA+LPS groups. At various time points, the phosphorylation of JNK in each group was measured by western blotting. Additionally, the productions of IL-6 and IL-8 were assessed using an enzyme-linked immunosorbent assay (ELISA). The effects of SP600125, an inhibitor of the JNK pathway, on the increase of p-JNK, IL-6, and IL-8 were also studied. Results. Our results showed that either PLA or LPS treatment alone can significantly increase the phosphorylation level of JNK in NCI-H292 cells. Of interest was the combined use of PLA and LPS that has a synergistic effect on the phosphorylation of JNK, as well as synergistically inducing the release of IL-6 and IL-8 in NCI-H292 cells. Furthermore, SP600125 significantly inhibited the activation of JNK signal, as well as reducing the productions of IL-6 and IL-8 in response to PLA+LPS stimulation. Conclusions. The JNK signaling pathway contributes to the release of IL-6 and IL-8, which is stimulated by the synergistic actions of PLA+LPS in NCI-H292 cells.