The roles of microRNAs and protein components of the microRNA pathway in lung development and diseases

Autocrine insulin-like growth factor 2 signaling as a potential target in the associated development of pulmonary emphysema and cancer in smokers

BACKGROUND

Tobacco smoking causes pulmonary inflammation, resulting in emphysema, an independent risk factor for lung cancer. Induction of insulin-like growth factor 2 (IGF2) in response to lung injury by tobacco carcinogens, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and polycyclic aromatic hydrocarbon benzo[a]pyrene in combination (NB), is critical for the proliferation of alveolar type 2 cells (AT2s) for lung repair. However, persistent IGF2 overexpression during NB-induced severe injury results in hyperproliferation of AT2s without coordinated AT2-to-AT1 differentiation, disrupting alveolar repair, which leads to the concurrent development of emphysema and lung cancer. The current study aims to verify the role of IGF2 signaling in the associated development of emphysema and cancer and develop effective pharmaceuticals for the diseases using animal models that recapitulate the characteristics of these chronic diseases.

METHODS

The pathogenesis of pulmonary emphysema and cancer was analyzed by lung function testing, histological evaluation, in situ zymography, dihydroethidium staining, and immunofluorescence and immunohistochemistry analyses utilizing mouse models of emphysema and cancer established by moderate exposure to NB for up to seven months.

RESULTS

Moderate NB exposure induced IGF2 expression in AT2s during the development of pulmonary emphysema and lung cancer in mice. Using AT2-specific insulin receptor knockout mice, we verified the causative role of sustained IGF2 signaling activation in AT2s in emphysema development. IGF2-targeting strategies, including voltage-dependent calcium channel blocker (CCB) and a neutralizing antibody, significantly suppressed the NB-induced development of emphysema and lung cancer. A publicly available database revealed an inverse correlation between the use of calcium channel blockers and a COPD diagnosis.

CONCLUSIONS

Our work confirms sustained IGF2 signaling activation in AT2s couples impaired lung repair to the concurrent development of emphysema and cancer in mice. Additionally, CCB and IGF2-specific neutralizing antibodies are effective pharmaceuticals for the two diseases.

LncRNA MRAK052509 competitively adsorbs miR-204-3p to regulate silica dust-induced EMT process

Silicosis is a systemic disease caused by long-term inhalation of free SiO2 and retention in the lungs. At present, it is still the most important occupational health hazard disease in the world. Existing studies have shown that non-coding RNA can also participate in complex fibrosis regulatory networks. However, its role in regulating silicotic fibrosis is still unclear. In this study, we constructed a NR8383/RLE-6TN co-culture system to simulate the pathogenesis of silicosis in vitro. Design of miR-204-3p mimics and inhibitors to overexpress or downregulate miR-204-3p in RLE-6TN cells. Design of short hairpin RNA (sh-RNA) to downregulate MRAK052509 in RLE-6TN cells. The regulatory mechanism of miR-204-3p and LncRNA MRAK052509 on EMT process was studied by Quantitative real-time PCR, Western blotting, Immunofluorescence and Cell scratch test. The results revealed that miR-204-3p affects the occurrence of silica dust-induced cellular EMT process mainly through regulating TGF-βRΙ, a key molecule of TGF-β signaling pathway. In contrast, Lnc MRAK052509 promotes the EMT process in epithelial cells by competitively adsorbing miR-204-3p and reducing its inhibitory effect on the target gene TGF-βRΙ, which may influence the development of silicosis fibrosis. This study perfects the targeted regulation relationship between LncRNA MRAK052509, miR-204-3p and TGF-βRΙ, and may provide a new strategy for the study of the pathogenesis and treatment of silicosis.

Unlocking the potential of RNA-based therapeutics in the lung: current status and future directions

Awareness of RNA-based therapies has increased after the widespread adoption of mRNA vaccines against SARS-CoV-2 during the COVID-19 pandemic. These mRNA vaccines had a significant impact on reducing lung disease and mortality. They highlighted the potential for rapid development of RNA-based therapies and advances in nanoparticle delivery systems. Along with the rapid advancement in RNA biology, including the description of noncoding RNAs as major products of the genome, this success presents an opportunity to highlight the potential of RNA as a therapeutic modality. Here, we review the expanding compendium of RNA-based therapies, their mechanisms of action and examples of application in the lung. The airways provide a convenient conduit for drug delivery to the lungs with decreased systemic exposure. This review will also describe other delivery methods, including local delivery to the pleura and delivery vehicles that can target the lung after systemic administration, each providing access options that are advantageous for a specific application. We present clinical trials of RNA-based therapy in lung disease and potential areas for future directions. This review aims to provide an overview that will bring together researchers and clinicians to advance this burgeoning field.

Intrauterine Smoke Exposure, microRNA Expression during Human Lung Development, and Childhood Asthma

Intrauterine smoke (IUS) exposure during early childhood has been associated with a number of negative health consequences, including reduced lung function and asthma susceptibility. The biological mechanisms underlying these associations have not been established. MicroRNAs regulate the expression of numerous genes involved in lung development. Thus, investigation of the impact of IUS on miRNA expression during human lung development may elucidate the impact of IUS on post-natal respiratory outcomes. We sought to investigate the effect of IUS exposure on miRNA expression during early lung development. We hypothesized that miRNA-mRNA networks are dysregulated by IUS during human lung development and that these miRNAs may be associated with future risk of asthma and allergy. Human fetal lung samples from a prenatal tissue retrieval program were tested for differential miRNA expression with IUS exposure (measured using placental cotinine concentration). RNA was extracted and miRNA-sequencing was performed. We performed differential expression using IUS exposure, with covariate adjustment. We also considered the above model with an additional sex-by-IUS interaction term, allowing IUS effects to differ by male and female samples. Using paired gene expression profiles, we created sex-stratified miRNA-mRNA correlation networks predictive of IUS using DIABLO. We additionally evaluated whether miRNAs were associated with asthma and allergy outcomes in a cohort of childhood asthma. We profiled pseudoglandular lung miRNA in n = 298 samples, 139 (47%) of which had evidence of IUS exposure. Of 515 miRNAs, 25 were significantly associated with intrauterine smoke exposure (q-value < 0.10). The IUS associated miRNAs were correlated with well-known asthma genes (e.g., ORM1-Like Protein 3, ORDML3) and enriched in disease-relevant pathways (oxidative stress). Eleven IUS-miRNAs were also correlated with clinical measures (e.g., Immunoglobulin E andlungfunction) in children with asthma, further supporting their likely disease relevance. Lastly, we found substantial differences in IUS effects by sex, finding 95 significant IUS-miRNAs in male samples, but only four miRNAs in female samples. The miRNA-mRNA correlation networks were predictive of IUS (AUC = 0.78 in males and 0.86 in females) and suggested that IUS-miRNAs are involved in regulation of disease-relevant genes (e.g., A disintegrin and metalloproteinase domain 19 (ADAM19), LBH regulator of WNT signaling (LBH)) and sex hormone signaling (Coactivator associated methyltransferase 1(CARM1)). Our study demonstrated differential expression of miRNAs by IUS during early prenatal human lung development, which may be modified by sex. Based on their gene targets and correlation to clinical asthma and atopy outcomes, these IUS-miRNAs may be relevant for subsequent allergy and asthma risk. Our study provides insight into the impact of IUS in human fetal lung transcriptional networks and on the developmental origins of asthma and allergic disorders.

Molecular mechanisms of cell death in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) in neonates is the most common pulmonary disease that causes neonatal mortality, has complex pathogenesis, and lacks effective treatment. It is associated with chronic obstructive pulmonary disease, pulmonary hypertension, and right ventricular hypertrophy. The occurrence and development of BPD involve various factors, of which premature birth is the most crucial reason for BPD. Under the premise of abnormal lung structure and functional product, newborns are susceptible to damage to oxides, free radicals, hypoxia, infections and so on. The most influential is oxidative stress, which induces cell death in different ways when the oxidative stress balance in the body is disrupted. Increasing evidence has shown that programmed cell death (PCD), including apoptosis, necrosis, autophagy, and ferroptosis, plays a significant role in the molecular and biological mechanisms of BPD and the further development of the disease. Understanding the mode of PCD and its signaling pathways can provide new therapeutic approaches and targets for the clinical treatment of BPD. This review elucidates the mechanism of BPD, focusing on the multiple types of PCD in BPD and their molecular mechanisms, which are mainly based on experimental results obtained in rodents.

Advancing Exposomic Research in Prenatal Respiratory Disease Programming

Disease programming reflects interactions between genes and the environment. Unlike the genome, environmental exposures and our response to exposures change over time. Starting in utero, the respiratory system and related processes develop sequentially in a carefully timed cascade, thus effects depend on both exposure dose and timing. A multitude of environmental and microbial exposures influence respiratory disease programming. Effects result from toxin-induced shifts in a host of molecular, cellular, and physiologic states and their interacting systems. Moreover, pregnant women and the developing child are not exposed to a single toxin, but to complex mixtures.

Integrative Analysis Reveals a miRNA-mRNA Regulatory Network and Potential Causative Agents in the Asthmatic Airway Epithelium

Background

During asthma progression, the intricate molecular networks, including microRNA (miRNA) transcriptional regulation in airway epithelium, remain largely undefined. The abnormal expression of miRNAs in asthmatic airway epithelium is a recent and fast-growing area in developing diagnostic and therapeutic targets for asthma.

Material and Methods

Analyses were conducted to compare airway epithelial miRNAs and gene expression between patients with asthma and healthy subjects from three datasets (two for miRNAs expression profiles and one for gene expression profile). The interactions network between differentially expressed (DE)-miRNAs and mRNAs was further identified for functional analysis. To verify the involvement and functions of all the identified miRNAs in asthma, we constructed two cellular models of asthma. The most promising causal miRNA candidate, miR-1246, was examined in an in vitro system to explore its targets and roles in asthma pathophysiology.

Results

Through integrative analysis, we obtained six miRNAs with 31 validated target genes in airway epithelium associated with asthma. Next, we confirmed that these miRNAs were all associated with asthma progression by in vitro functional experiments. They may participate in eosinophilic inflammation (miR-92b-3p, miR-1246, miR-197-3p, and miR-124-5p) or remodeling (miR-197-3p, miR-193a-5p, miR-1246, and miR-92b-3p). Additionally, some other non-screened valuable miRNAs were also examined and identified (miR-21-5p and miR-19b-3p), and some detected in blood correlated with the disease status. Furthermore, we found that miR-1246 could directly target POSTN and influence epithelial-to-mesenchymal transition and fibrosis in airway epithelial cells.

Conclusion

We constructed a preliminary epithelial regulatory network in asthma based on six identified miRNAs and their valuable target genes. Candidate factors in the biological miRNA-mRNA network in airway epithelium may provide further information on the pathogenesis of asthma. Strikingly, among all screened miRNAs, miR-1246, which could interact with POSTN may have multifunctional effects in the course of asthma and be a promising agent for asthma treatment and molecular subtyping.

Fetal lung underdevelopment is rescued by administration of amniotic fluid stem cell extracellular vesicles in rodents

Fetal lung underdevelopment, also known as pulmonary hypoplasia, is characterized by decreased lung growth and maturation. The most common birth defect found in babies with pulmonary hypoplasia is congenital diaphragmatic hernia (CDH). Despite research and clinical advances, babies with CDH still have high morbidity and mortality rates, which are directly related to the severity of lung underdevelopment. To date, there is no effective treatment that promotes fetal lung growth and maturation. Here, we describe a stem cell-based approach in rodents that enhances fetal lung development via the administration of extracellular vesicles (EVs) derived from amniotic fluid stem cells (AFSCs). Using fetal rodent models of pulmonary hypoplasia (primary epithelial cells, organoids, explants, and in vivo), we demonstrated that AFSC-EV administration promoted branching morphogenesis and alveolarization, rescued tissue homeostasis, and stimulated epithelial cell and fibroblast differentiation. We confirmed this regenerative ability in in vitro models of lung injury using human material, where human AFSC-EVs obtained following good manufacturing practices restored pulmonary epithelial homeostasis. Investigating EV mechanism of action, we found that AFSC-EV beneficial effects were exerted via the release of RNA cargo. MicroRNAs regulating the expression of genes involved in lung development, such as the miR17-92 cluster and its paralogs, were highly enriched in AFSC-EVs and were increased in AFSC-EV-treated primary lung epithelial cells compared to untreated cells. Our findings suggest that AFSC-EVs hold regenerative ability for underdeveloped fetal lungs, demonstrating potential for therapeutic application in patients with pulmonary hypoplasia.

Reactivation of Multiple Fetal miRNAs in Lung Adenocarcinoma

MicroRNAs (miRNAs) play vital roles in the regulation of normal developmental pathways. However, cancer cells can co-opt these miRNAs, and the pathways that they regulate, to drive pro-tumourigenic phenotypes. Characterization of the miRNA transcriptomes of fetal organs is essential for identifying these oncofetal miRNAs, but it has been limited by fetal sample availability. As oncofetal miRNAs are absent from healthy adult lungs, they represent ideal targets for developing diagnostic and therapeutic strategies. We conducted small RNA sequencing of a rare collection of 25 human fetal lung (FL) samples and compared them to two independent cohorts (n = 140, n = 427), each comprised of adult non-neoplastic lung (ANL) and lung adenocarcinoma (LUAD) samples. We identified 13 oncofetal miRNAs that were expressed in FL and LUAD but not in ANL. These oncofetal miRNAs are potential biomarkers for LUAD detection (AUC = 0.963). Five of these miRNAs are derived from the imprinted C14MC miRNA cluster at the 14q32 locus, which has been associated with cancer development and abnormal fetal and placental development. Additionally, we observed the pulmonary expression of 44 previously unannotated miRNAs. The sequencing of these fetal lung samples also provides a baseline resource against which aberrant samples can be compared.

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.

Aberrant Expression of Immune-related MicroRNAs in Pediatric Patients with Asthma

MicroRNAs (miRNAs) have been implicated as regulatory molecules that could play a considerable role in the pathogenesis of different diseases including asthma. This work aims at exploring the role of miR-146a and miR- 106b in the pathogenesis of asthma and their association with asthma severity, IgE, and inflammatory cytokines in asthmatic children. Thirty asthmatic children and twenty age-matched healthy children aged 4-17 years old were enrolled. Expression of plasma miR-146a and miR-106b was measured using quantitative real-time PCR. Plasma levels of interleukin-5 (IL-5) and interleukin-13 (IL-13) were assessed using ELISA. Lung functions were measured by Spirometry. MiR-146a and miR-106b were significantly over-expressed in asthmatic children compared to healthy children. A significant positive correlation between total IgE and both miR-146a and miR-106b was found while no significant correlation could be detected between these miRNAs and asthma severity in asthmatic children. Plasma levels of IL-5 and IL-13 were non-significantly higher in asthmatic children compared to healthy children, and there was no significant correlation between them and both miR-146a and miR-106b expressions in the asthmatic children. The aberrant expression of immune-related miRNAs (miR-146a and miR-106b) and inflammatory cytokines (IL-5 and IL-13) among asthmatic children suggest their probable role in asthma pathogenesis.

Mechanical stretch regulates the expression of specific miRNA in extracellular vesicles released from lung epithelial cells

The underlying mechanism of normal lung organogenesis is not well understood. An increasing number of studies are demonstrating that extracellular vesicles (EVs) play critical roles in organ development by delivering microRNAs (miRNA) to neighboring and distant cells. miRNAs are important for fetal lung growth; however, the role of miRNA-EVs (miRNAs packaged inside the EVs) during fetal lung development is unexplored. The aim of this study was to examine the expression of miRNA-EVs in MLE-12, a murine lung epithelial cell line subjected to mechanical stretch in vitro with the long-term goal to investigate their potential role in the fetal lung development. Both cyclic and continuous mechanical stretch regulate miRNA differentially in EVs released from MLE-12 and intracellularly, demonstrating that mechanical signals regulate the expression of miRNA-EVs in lung epithelial cells. These results provide a proof-of-concept for the potential role that miRNA-EVs could play in the development of fetal lung.

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.

Asthma diagnosis using integrated analysis of eosinophil microRNAs

BACKGROUND

Asthma is a syndrome characterized by airway inflammation and obstruction. Due to its heterogeneity, the difficulties in asthma diagnosis and treatment make the discovery of new biomarkers a focus of research. So, we determined the differential miRNA expression of eosinophils between healthy and asthmatic patients and to establish a differentially expressed miRNA profile detectable in sera for use as biomarker.

METHODS

MicroRNAs from peripheral eosinophils from healthy and asthmatic subjects were isolated and analyzed by next-generation sequencing and confirmed by quantitative PCR in 29 asthmatics and 10 healthy individuals. The levels of serum miRNAs were performed by quantitative PCR in 138 asthmatics and 39 healthy subjects. Regression analysis and Random Forest models were performed.

RESULTS

We found a set of miRNAs whose expression differs between eosinophils from asthmatics and healthy subjects. These miRNAs can classify asthmatics into two clusters that differed in the number of eosinophils and periostin concentration in serum. Some of these miRNAs were also confirmed in sera, as miR-185-5p which discriminates asthmatics from healthy subjects. Together with other two miRNAs, miR-185-5p allowed us to create a logistic regression model to discriminate better both conditions and a Random Forest model that can even sort the asthmatics into intermittent, mild persistent, moderate persistent, and severe persistent asthma.

CONCLUSION

Our data show that miRNAs profile in eosinophils can be used as asthma diagnosis biomarker in serum and that this profile is able to rank asthma severity.

Building and Regenerating the Lung Cell by Cell

The unique architecture of the mammalian lung is required for adaptation to air breathing at birth and thereafter. Understanding the cellular and molecular mechanisms controlling its morphogenesis provides the framework for understanding the pathogenesis of acute and chronic lung diseases. Recent single-cell RNA sequencing data and high-resolution imaging identify the remarkable heterogeneity of pulmonary cell types and provides cell selective gene expression underlying lung development. We will address fundamental issues related to the diversity of pulmonary cells, to the formation and function of the mammalian lung, and will review recent advances regarding the cellular and molecular pathways involved in lung organogenesis. What cells form the lung in the early embryo? How are cell proliferation, migration, and differentiation regulated during lung morphogenesis? How do cells interact during lung formation and repair? How do signaling and transcriptional programs determine cell-cell interactions necessary for lung morphogenesis and function?

Recent advances in the pathogenesis of BPD

Bronchopulmonary dysplasia (BPD) continues to be one of the most common complications of preterm birth and is characterized histopathologically by impaired lung alveolarization. Extremely preterm born infants remain at high risk for the development of BPD, highlighting a pressing need for continued efforts to understand the pathomechanisms at play in affected infants. This brief review summarizes recent progress in our understanding of the how the development of the newborn lung is stunted, highlighting recent reports on roles for growth factor signaling, oxidative stress, inflammation, the extracellular matrix and proteolysis, non-coding RNA, and fibroblast and epithelial cell plasticity. Additionally, some concerns about modeling BPD in experimental animals are reviewed, as are new developments in the in vitro modeling of pathophysiological processes relevant to impaired lung alveolarization in BPD.

Prediction of microRNA-binding residues in protein using a Laplacian support vector machine based on sequence information

The identification of microRNA (miRNA)-binding protein residues significantly impacts several research areas, including gene regulation and expression. We propose a method, PmiRBR, which combines a novel hybrid feature with the Laplacian support vector machine (LapSVM) algorithm to predict miRNA-binding residues in protein sequences. The hybrid feature is constituted by secondary structure, conservation scores, and a novel feature, which includes evolutionary information combined with the physicochemical properties of amino acids. Performance comparisons of the various features indicate that our novel feature contributes the most to prediction improvement. Our results demonstrate that PmiRBR can achieve 85.96% overall accuracy, with 43.89% sensitivity and 90.56% specificity. PmiRBR significantly outperforms other approaches at miRNA-binding residue prediction.

Comparative expression analysis identifies the respiratory transition-related miRNAs and their target genes in tissues of metamorphosing Chinese giant salamander (Andrias davidianus)

Background

Chinese giant salamander (Andrias davidianus) undergoes a metamorphosis from aquatic larvae to terrestrial adults, with concomitant transfer of respiration from gills to lungs prior to metamorphosis. These two tissues, as well as skin, were sampled to identify the differentially expressed miRNAs.

Results

High-coverage reference transcriptome was generated from combined gill, lung and skin tissues of metamorphosing juveniles, and lung tissue of adults: 86,282 unigenes with total length of approximately 77,275,634 bp and N50 of 1732 bp were obtained. Among these, 13,246 unigenes were assigned to 288 pathways. To determine the possible involvement of miRNAs in the respiratory transition, small RNA libraries were sequenced; 282 miRNAs were identified, 65 among which were known and 217 novel. Based on the hierarchical clustering analysis, the twelve studied samples were classified into three major clusters using differentially expressed miRNAs. We have validated ten differentially expressed miRNAs and some of their related target genes using qPCR. These results largely corroborated the results of transcriptomic and miRNA analyses. Finally, an miRNA-gene-network was constructed. Among them, two miRNAs with target genes related to oxygen sensing were differentially expressed between gill and lung tissues. Three miRNAs were differentially expressed between the lungs of larvae and lungs of adults.

Conclusions

This study provides the first large-scale miRNA expression profile overview during the respiration transition from gills to lungs in Chinese giant salamander. Five differentially expressed miRNAs and their target genes were identified among skin, gill and lung tissues. These results suggest that miRNA profiles in respiratory tissues play an important role in the regulation of respiratory transition.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4662-5) contains supplementary material, which is available to authorized users.

Evidence establishing a link between prenatal and early-life stress and asthma development

PURPOSE OF REVIEW

The objective of this review is to provide an update on our evolving understanding of the effects of stress in pregnancy and during early development on the onset of asthma-related phenotypes across childhood, adolescence, and into early adulthood.

RECENT FINDINGS

Accumulating evidence over the past 2 decades has established that prenatal and early-life psychological stress and stress correlates (e.g., maternal anxiety or depression) increase the risk for childhood respiratory disorders. Recent systematic reviews and meta-analyses including numerous prospective epidemiological and case-control studies substantiate a significant effect of prenatal stress and stress in early childhood on the development of wheeze, asthma, and other atopic-related disorders (eczema and allergic rhinitis), with many studies showing an exposure-response relationship. Offspring of both sexes are susceptible to perinatal stress, but effects differ. The impact of stress on child wheeze/asthma can also be modified by exposure timing. Moreover, coexposure to prenatal stress can enhance the effect of chemical stressors, such as prenatal traffic-related air pollution, on childhood respiratory disease risk. Understanding complex interactions among exposure dose, timing, child sex, and concurrent environmental exposures promises to more fully characterize stress effects and identify susceptible subgroups. Although the link between perinatal stress and childhood asthma-related phenotypes is now well established, pathways by which stress predisposes children to chronic respiratory disorders are not as well delineated. Mechanisms central to the pathophysiology of wheeze/asthma and lung growth and development overlap and involve a cascade of events that include disrupted immune, neuroendocrine, and autonomic function as well as oxidative stress. Altered homeostatic functioning of these integrated systems during development can enhance vulnerability to asthma and altered lung development.

SUMMARY

Mechanistic studies that more comprehensively assess biomarkers reflecting alterations across interrelated stress response systems and associated regulatory processes, in both pregnant women and young children, could be highly informative. Leveraging high-throughput systems-wide technologies to include epigenomics (e.g., DNA methylation, microRNAs), transcriptomics, and microbiomics as well as integrated multiomics are needed to advance this field of science. Understanding stress-induced physiological changes occurring during vulnerable life periods that contribute to chronic respiratory disease risk could lead to the development of preventive strategies and novel therapeutic interventions.

A Circulating MicroRNA Signature Serves as a Diagnostic and Prognostic Indicator in Sarcoidosis

MicroRNAs (miRNAs) act as post-transcriptional regulators of gene expression. In sarcoidosis, aberrant miRNA expression may enhance immune responses mounted against an unknown antigenic agent. We tested whether a distinct miRNA signature functions as a diagnostic biomarker and explored its role as an immune modulator in sarcoidosis. The expression of miRNAs in peripheral blood mononuclear cells from subjects who met clinical and histopathologic criteria for sarcoidosis was compared with that observed in matched controls in the ACCESS (A Case Controlled Etiologic Study of Sarcoidosis) study. Signature miRNAs were determined by miRNA microarray analysis and validated by quantitative RT-PCR. Microarray analysis identified 54 mature, human feature miRNAs that were differentially expressed between the groups. Significant feature miRNAs that distinguished subjects with sarcoidosis from controls were selected by means of probabilistic models adjusted for clinical variables. Eight signature miRNAs were chosen to verify the diagnosis of sarcoidosis in a validation cohort, and distinguished subjects with sarcoidosis from controls with a positive predictive value of 88%. We identified both novel and previously described genes and molecular pathways associated with sarcoidosis as targets of these signature miRNAs. Additionally, we demonstrate that signature miRNAs (hsa-miR-150-3p and hsa-miR-342-5p) are significantly associated with reduced lymphocytes and airflow limitations, both of which are known markers of a poor prognosis. Together, these findings suggest that a circulating miRNA signature serves as a noninvasive biomarker that supports the diagnosis of sarcoidosis. Future studies will test the miRNA signature as a prognostication tool to identify unfavorable changes associated with poor clinical outcomes in sarcoidosis.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

MicroRNA-661 promotes non-small cell lung cancer progression by directly targeting RUNX3

Lung cancer is the primary cause of cancer‑associated mortality in men and women worldwide. Increasing evidence indicates that abnormal microRNA (miRNA) expression contributes to the carcinogenesis and progression of multiple human cancers, including non‑small cell lung cancer (NSCLC). Therefore, miRNAs exhibit the potential to act as biomarkers for the diagnosis, treatment and prognosis of human malignancies. miRNA‑661 (miR‑661) has previously been demonstrated to be important in the development of various human cancer types. However, the expression levels, functions and underlying mechanisms of miR‑661 in NSCLC remain to be elucidated. The present study demonstrated that miR‑661 was upregulated in NSCLC tissues and cell lines. In addition, miR‑661 expression levels were significantly correlated with differentiation and tumor stage lymph node metastasis of NSCLC patients. Functional experiments demonstrated that miR-661 downregulation inhibited NSCLC cell proliferation and invasion in vitro. Furthermore, runt‑related transcription factor 3 (RUNX3) was identified as a direct target of miR‑661 in NSCLC. RUNX3 was expressed at a low level in NSCLC tissues and was negatively correlated with the miR‑661 expression level. Further experiments revealed that RUNX3 knockdown significantly rescued the effects of miR‑661 underexpression on NSCLC cell proliferation and invasion. In conclusion, the present findings indicated a role for miR‑661 as an oncogene in NSCLC via direct targeting of RUNX3, thus suggesting that miR‑661 may be used to develop novel therapies for NSCLC patients.

MicroRNA-107-5p suppresses non-small cell lung cancer by directly targeting oncogene epidermal growth factor receptor

MicroRNAs (miRNAs) are dysregulated in cancers, including human non-small cell lung cancer (NSCLC). The function of MicroRNA-107-5p (miR-107-5p) in NSCLC is not fully elucidated. Epidermal growth factor receptor (EGFR) is a cancer-driven gene in tumorigenesis. In this study, we found that miR-107-5p was significantly decreased in NSCLC tissues and NSCLC cell lines. Moreover, our results indicated that miR-107-5p could suppress cell proliferation, inhibit metastasis, impede cell cycle, and promote apoptosis via directly targeting EGFR. We also investigated roles of miR-107-5p in vivo. The results showed that it could inhibit tumor growth. Therefore, our study demonstrated that miR-107-5p not only suppressed the progression in NSCLC cells by inhibiting the expression of EGFR, but also could be a promising and a new potential therapeutic target for lung cancer.

Identification of microRNAs associated with allergic airway disease using a genetically diverse mouse population

Background

Allergic airway diseases (AADs) such as asthma are characterized in part by granulocytic airway inflammation. The gene regulatory networks that govern granulocyte recruitment are poorly understood, but evidence is accruing that microRNAs (miRNAs) play an important role. To identify miRNAs that may underlie AADs, we used two complementary approaches that leveraged the genotypic and phenotypic diversity of the Collaborative Cross (CC) mouse population. In the first approach, we sought to identify miRNA expression quantitative trait loci (eQTL) that overlap QTL for AAD-related phenotypes. Specifically, CC founder strains and incipient lines of the CC were sensitized and challenged with house dust mite allergen followed by measurement of granulocyte recruitment to the lung. Total lung RNA was isolated and miRNA was measured using arrays for CC founders and qRT-PCR for incipient CC lines.

Results

Among CC founders, 92 miRNAs were differentially expressed. We measured the expression of 40 of the most highly expressed of these 92 miRNAs in the incipient lines of the CC and identified 18 eQTL corresponding to 14 different miRNAs. Surprisingly, half of these eQTL were distal to the corresponding miRNAs, and even on different chromosomes. One of the largest-effect local miRNA eQTL was for miR-342-3p, for which we identified putative causal variants by bioinformatic analysis of the effects of single nucleotide polymorphisms on RNA structure. None of the miRNA eQTL co-localized with QTL for eosinophil or neutrophil recruitment. In the second approach, we constructed putative miRNA/mRNA regulatory networks and identified three miRNAs (miR-497, miR-351 and miR-31) as candidate master regulators of genes associated with neutrophil recruitment. Analysis of a dataset from human keratinocytes transfected with a miR-31 inhibitor revealed two target genes in common with miR-31 targets correlated with neutrophils, namely Oxsr1 and Nsf.

Conclusions

miRNA expression in the allergically inflamed murine lung is regulated by genetic loci that are smaller in effect size compared to mRNA eQTL and often act in trans. Thus our results indicate that the genetic architecture of miRNA expression is different from mRNA expression. We identified three miRNAs, miR-497, miR-351 and miR-31, that are candidate master regulators of genes associated with neutrophil recruitment. Because miR-31 is expressed in airway epithelia and is predicted to target genes with known links to neutrophilic inflammation, we suggest that miR-31 is a potentially novel regulator of airway inflammation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1732-9) contains supplementary material, which is available to authorized users.