Identification of microRNAs changed in the neonatal lungs in response to hyperoxia exposure

Gender and sex hormone effects on neonatal innate immune function

OBJECTIVES

Scientific evidence provides a widened view of differences in immune response between male and female neonates. The X-chromosome codes for several genes important in the innate immune response and neonatal innate immune cells express receptors for, and are inhibited by, maternal sex hormones. We hypothesized that sex differences in innate immune responses may be present in the neonatal population which may contribute to the increased susceptibility of premature males to sepsis. We aimed to examine the in vitro effect of pro-inflammatory stimuli and hormones in neutrophils and monocytes of male and female neonates, to examine the expression of X-linked genes involved in innate immunity and the miRNA profiles in these populations.

METHODS

Preterm infants (n = 21) and term control (n = 19) infants were recruited from the Coombe Women and Infants University Hospital Dublin with ethical approval and explicit consent. The preterm neonates (eight female, 13 male) were recruited with a mean gestation at birth (mean ± SD) of 28 ± 2 weeks and corrected gestation at the time of sampling was 30 + 2.6 weeks. The mean birth weight of preterm neonates was 1084 ± 246 g. Peripheral blood samples were used to analyze immune cell phenotypes, miRNA human panel, and RNA profiles for inflammasome and inflammatory genes.

RESULTS

Dividing neutrophil results by sex showed no differences in baseline CD11b between sexes among either term or preterm neonates. Examining monocyte CD11b by sex shows, that at baseline, total and classical monocytes have higher CD11b in preterm females than preterm males. Neutrophil TLR2 did not differ between sexes at baseline or following lipopolysaccharide (LPS) exposure. CD11b expression was higher in preterm male non-classical monocytes following Pam3CSK treatment when compared to females, a finding which is unique to our study. Preterm neonates had higher TLR2 expression at baseline in total monocytes, classical monocytes and non-classical monocytes than term. A sex difference was evident between preterm females and term females in TLR2 expression only. Hormone treatment showed no sex differences and there was no detectable difference between males and females in X-linked gene expression. Two miRNAs, miR-212-3p and miR-218-2-3p had significantly higher expression in preterm female than preterm male neonates.

CONCLUSIONS

This study examined immune cell phenotypes and x-linked gene expression in preterm neonates and stratified according to gender. Our findings suggest that the responses of females mature with advancing gestation, whereas male term and preterm neonates have very similar responses. Female preterm neonates have improved monocyte activation than males, which likely reflects improved innate immune function as reflected clinically by their lower risk of sepsis. Dividing results by sex showed changes in preterm and term infants at baseline and following LPS stimulation, a difference which is reflected clinically by infection susceptibility. The sex difference noted is novel and may be limited to the preterm or early neonatal population as TLR2 expression on monocytes of older children does not differ between males and females. The differences shown in female and male innate immune cells likely reflect a superior innate immune defense system in females with sex differences in immune cell maturation. Existing human studies on sex differences in miRNA expression do not include preterm patients, and most frequently use either adult blood or cord blood. Our findings suggest that miRNA profiles are similar in neonates of opposite sexes at term but require further investigation in the preterm population. Our findings, while novel, provide only very limited insights into sex differences in infection susceptibility in the preterm population leaving many areas that require further study. These represent important areas for ongoing clinical and laboratory study and our findings represent an important contribution to exiting literature.

Gpnmb silencing protects against hyperoxia-induced acute lung injury by inhibition of mitochondrial-mediated apoptosis

Background: Hyperoxia-induced acute lung injury (HALI) is a complication to ventilation in patients with respiratory failure, which can lead to acute inflammatory lung injury and chronic lung disease. The aim of this study was to integrate bioinformatics analysis to identify key genes associated with HALI and validate their role in H2O2-induced cell injury model.Methods: Integrated bioinformatics analysis was performed to screen vital genes involved in hyperoxia-induced lung injury (HLI). CCK-8 and flow cytometry assays were performed to assess cell viability and apoptosis. Western blotting was performed to assess protein expression.Results: In this study, glycoprotein non-metastatic melanoma protein B (Gpnmb) was identified as a key gene in HLI by integrated bioinformatics analysis of 4 Gene Expression Omnibus (GEO) datasets (GSE97804, GSE51039, GSE76301 and GSE87350). Knockdown of Gpnmb increased cell viability and decreased apoptosis in H2O2-treated MLE-12 cells, suggesting that Gpnmb was a proapoptotic gene during HALI. Western blotting results showed that knockdown of Gpnmb reduced the expression of Bcl-2 associated X (BAX) and cleaved-caspase 3, and increased the expression of Bcl-2 in H2O2 treated MLE-12 cells. Furthermore, Gpnmb knockdown could significantly reduce reactive oxygen species (ROS) generation and improve the mitochondrial membrane potential.Conclusion: The present study showed that knockdown of Gpnmb may protect against HLI by repressing mitochondrial-mediated apoptosis.

The vascular phenotype of BPD: new basic science insights-new precision medicine approaches

Bronchopulmonary dysplasia (BPD) is the most common complication of preterm birth. Up to 1/3 of children with BPD develop pulmonary hypertension (PH). PH increases mortality, the risk of adverse neurodevelopmental outcome and lacks effective treatment. Current vasodilator therapies address symptoms, but not the underlying arrested vascular development. Recent insights into placental biology and novel technological advances enabling the study of normal and impaired lung development at the single cell level support the concept of a vascular phenotype of BPD. Dysregulation of growth factor pathways results in depletion and dysfunction of putative distal pulmonary endothelial progenitor cells including Cap1, Cap2, and endothelial colony-forming cells (ECFCs), a subset of vascular progenitor cells with self-renewal and de novo angiogenic capacity. Preclinical data demonstrate effectiveness of ECFCs and ECFC-derived particles including extracellular vesicles (EVs) in promoting lung vascular growth and reversing PH, but the mechanism is unknown. The lack of engraftment suggests a paracrine mode of action mediated by EVs that contain miRNA. Aberrant miRNA signaling contributes to arrested pulmonary vascular development, hence using EV- and miRNA-based therapies is a promising strategy to prevent the development of BPD-PH. More needs to be learned about disrupted pathways, timing of intervention, and mode of delivery. IMPACT: Single-cell RNA sequencing studies provide new in-depth view of developmental endothelial depletion underlying BPD-PH. Aberrant miRNA expression is a major cause of arrested pulmonary development. EV- and miRNA-based therapies are very promising therapeutic strategies to improve prognosis in BPD-PH.

Integrated MicroRNA-mRNA Analyses of Distinct Expression Profiles in Hyperoxia-Induced Bronchopulmonary Dysplasia in Neonatal Mice

OBJECTIVE

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease of preterm neonates; the underlying pathogenesis is not fully understood. Recent studies suggested microRNAs (miRNAs) may be involved in BPD.

STUDY DESIGN

miRNA and mRNA microarrays were performed to analyze the expression profiles of miRNA and mRNA in BPD and control lung tissues after oxygen and air exposure on day 21. Bioinformatics methods, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), were performed to predict the potential functions of differentially expressed genes. Then, miRNA-mRNA regulatory network was constructed by protein-protein interaction (PPI) data and TarBase data.

RESULTS

Our results showed that a total of 192 differentially expressed miRNAs (74 downregulated and 118 upregulated) and 1,225 differentially expressed mRNAs (479 downregulated and 746 upregulated) were identified between BPD mice and normoxia-control mice. GO and KEGG analysis showed that for downregulated genes, the top significant enriched GO terms and KEGG pathways were both mainly related to immune and inflammation processes; for upregulated genes, the top significant enriched GO terms and KEGG pathways were both mainly related to extracellular matrix (ECM) remodeling. PPI network and miRNA-mRNA regulatory network construction revealed that the key genes and pathways associated with inflammation and immune regulation.

CONCLUSION

Our findings revealed the integrated miRNA-mRNA data of distinct expression profiles in hyperoxia-induced BPD mice, and may provide some clues of the potential biomarkers for BPD, and provide novel insights into the development of new promising biomarkers for the treatment of BPD.

KEY POINTS

· Integrated advanced bioinformatics methods may offer a better way to understand the molecular expression profiles involved in BPD.. · ECM remodeling, inflammation, and immune regulation may be essential to BPD.. · The miRNA-mRNA regulatory network construction may contribute to develop new biomarkers for the treatment of BPD..

LncRNA SNHG6 accelerates hyperoxia-induced lung cell injury via regulating miR-335 to activate KLF5/NF-κB pathway

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in premature infants, and its pathogenesis has not been clarified. Long non-coding RNAs (lncRNA) have important functions in cell bioactivity. However, their role in developmental lung disease remains unclear.

OBJECTIVE

The aim of this study was to demonstrate the role of lncRNA SNHG6 (SNHG6) in BPD and its underlying mechanisms.

METHODS

The blood of patients with BPD were collected, and BPD model of BEAS-2B cells was established by hyperoxia method. SNHG6, miR-335 and KLF5 mRNA expression were detected by RT-qPCR. Western blot was conducted to measure the levels of apoptosis-related proteins' expression and NF-κB pathway related proteins. BEAS-2B cell viability and apoptosis were assessed by CCK-8 and flow cytometry, respectively. Assay Kit was applied to detect ROS, MDA and SOD levels, respectively. ELISA was performed to assess the levels of inflammatory factors. The binding site of miR-335 with SNHG6 or KLF5 were predicted by using DIANA or TargetScan, and which was verified by double luciferase reporter assay.

RESULTS

Firstly, SNHG6 was highly expressed and miR-335 was lowly expressed in BPD model, SNHG6 knockdown and miR-335 mimics both alleviated hyperoxia-induced lung cell injury, and SNHG6 targeted miR-335. Subsequently, KLF5 was targeted by miR-335, and KLF5 promoted lung cell injury via activating NF-κB pathway. Furthermore, SNHG6 mediated lung cell injury via regulating the miR-335/KLF5/NF-κB pathway.

CONCLUSION

Our research confirmed that SNHG6 mediated hyperoxia-induced lung cell injury via regulating the miR-335/KLF5/NF-κB pathway. These findings suggest that SNHG6 serves as promising targets for the treatment of newborns with BPD.

Hyperoxia Induced Bronchopulmonary Dysplasia-Like Inflammation via miR34a-TNIP2-IL-1β Pathway

Lung injury induced by oxygen is a key contributor to the pathogenesis of preterm infant bronchopulmonary dysplasia (BPD). To date, there are comprehensive therapeutic strategy for this disease, but the underlying mechanism is still in progress. By using lentivirus, we constructed microRNA34a (miR34a)-overexpressing or knockdown A549 cell lines, and exposure to hyperoxia to mimic oxygen induce lung injury. In this study, we investigated 4 proinflammatory cytokines, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), angiopoietin-1 (Ang-1), and Cyclooxygenase-2 (COX-2) in the secreted sputum of infants who received mechanical ventilation, and found that IL-1β was substantially elevated in the first week after oxygen therapy and with no significant decrease until the fourth week, while TNF-α, Ang-1, and COX-2 were increased in the first week but decreased quickly in the following weeks. In addition, in vitro assay revealed that hyperoxia significantly increased the expression of miR-34a, which positively regulated the proinflammatory cytokine IL-1β in a time- and concentration-dependent manner in A549 cells. Overexpressing or knockdown miR34 would exacerbate or inhibit production of IL-1β and its upstream NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome signaling pathway. Mechanically, it's found that TNFAIP3 interacting protein 2 (TNIP2), an inhibitor of nuclear factor κB (NF-κB), is a direct target of miR34a, negatively regulated activation of NLRP3 inflammasome and the production of IL-1β. Overexpressing TNIP2 ameliorated hyperoxia-induced production of IL-1β and cell apoptosis. Our findings suggest that TNIP2 may be a potential clinical marker in the diagnosis of BPD.

Inhibition of miR-21 improves pulmonary vascular responses in bronchopulmonary dysplasia by targeting the DDAH1/ADMA/NO pathway

miR-21 has been confirmed to be overexpressed in neonatal rat lungs with hyperoxia-mediated bronchopulmonary dysplasia (BPD). The specific function of miR-21 in BPD is still unclear. We established the hyperoxia-induced BPD rat model in vivo and the hyperoxia-induced pulmonary microvascular endothelial cells (PMVECs) model in vitro. Transwell assay was utilized to detect the migratory capability of PMVECs. Tube formation assay was utilized to measure angiogenesis ability. ELISA was utilized to test nitric oxide (NO) production and the intracellular and extracellular Asymmetric Dimethylarginine (ADMA) concentration. Furthermore, the interaction between miR-21 and dimethylarginine dimethylaminohydrolase 1 (DDAH1) was evaluated using luciferase reporter assay. We found that miR-21 expression in PMVECs was increased by hyperoxia stimulation. Inhibition of miR-21 improved the migratory and angiogenic activities of PMVECs and overexpression of miR-21 exerted the opposite effects. Furthermore, knockdown of miR-21 increased NO production and decreased intracellular and extracellular ADMA concentration in hyperoxia-treated PMVECs. Next we proved that miR-21 could bind to DDAH1 and negatively regulate its expression. Rescues assays showed that DDAH1 knockdown reversed the effects of miR-21 depletion on hyperoxia-mediated PMVEC functions, NO production, and ADMA concentration. Importantly, miR-21 downregulation restored alveolarization and vascular density in BPD rats. This study demonstrates that inhibition of miR-21 improves pulmonary vascular responses in BPD by targeting the DDAH1/ADMA/NO pathway.

Insight Into the Roles of Non-coding RNA in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease most commonly occurring in premature infants, and its pathological manifestations are alveolar hypoplasia and dysregulation of pulmonary vasculature development. The effective treatment for BPD has not yet been established. Non-coding RNAs, including microRNAs and long non-coding RNAs do not encode proteins, but can perform its biological functions at the RNA level. Non-coding RNAs play an important role in the incidence and development of BPD by regulating the expression of genes related to proliferation, apoptosis, angiogenesis, inflammation and other cell activities of alveolar epithelial cells and vascular endothelial cells. Here we summarize the role of non-coding RNAs in BPD, which provides possible molecular marker and therapeutic target for the diagnosis and treatment of BPD.

Ferroptosis is Involved in Hyperoxic Lung Injury in Neonatal Rats

Purpose

To evaluate whether ferroptosis is involved in hyperoxic acute lung injury (HALI) and its mechanisms through the HALI model.

Methods

HE staining was used to assess lung injury pathology after the establishment of neonatal rat HALI model. ELISA was used to detect ROS, GPX4, and GSH expression. Prussian blue staining and Western Blot were used to detect iron deposition and the expression of ferroptosis-related proteins, respectively.

Results

The HALI group showed pathological changes with larger and fewer alveoli and thicker alveolar septa after HE staining. Prussian blue staining detected significant iron deposition in the lung tissue of the HALI group. GPX4, GSH, GSS, and SLC7A11 expressions were significantly decreased in the HALI group than in the normal control group. In contrast, ROS, TFRC, FHC, and FLC expressions showed opposite results (p<0.05).

Conclusion

Ferroptosis may be involved in the pathological process of hyperoxic lung injury in neonatal rats.

Hyperoxia-induced miR-342-5p down-regulation exacerbates neonatal bronchopulmonary dysplasia via the Raf1 regulator Spred3

BACKGROUND AND PURPOSE

Bronchopulmonary dysplasia (BPD) is the most prevalent chronic paediatric lung disease and is linked to the development of chronic obstructive pulmonary disease. MicroRNA-based regulation of type II alveolar epithelial cell (T2AEC) proliferation and apoptosis is an important factor in the pathogenesis of BPD and warrants further investigation.

EXPERIMENTAL APPROACH

Two murine models of hyperoxic lung injury (with or without miR-342-5p or Sprouty-related, EVH1 domain-containing protein 3 [Spred3] modulation) were employed: a hyperoxia-induced acute lung injury model (100% O₂ on postnatal days 1-7) and the BPD model (100% O₂ on postnatal days 1-4, followed by room air for 10 days). Tracheal aspirate pellets from healthy control and moderate/severe BPD neonates were randomly selected for clinical miR-342-5p analysis.

KEY RESULTS

Hyperoxia decreased miR-342-5p levels in primary T2AECs, MLE12 cells and neonatal mouse lungs. Transgenic miR-342 overexpression in neonatal mice ameliorated survival rates and improved the BPD phenotype and BPD-associated pulmonary arterial hypertension (PAH). T2AEC-specific miR-342 transgenic overexpression, as well as miR-342-5p mimic therapy, also ameliorated the BPD phenotype and associated PAH. miR-342-5p targets the 3'UTR of the Raf1 regulator Spred3, inhibiting Spred3 expression. Treatment with recombinant Spred3 exacerbated the BPD phenotype and associated PAH. Notably, miR-342-5p inhibition under room air conditions did not mimic the BPD phenotype. Moderate/severe BPD tracheal aspirate pellets exhibited decreased miR-342-5p levels relative to healthy control pellets.

CONCLUSION AND IMPLICATIONS

These findings suggest that miR-342-5p mimic therapy may show promise in the treatment or prevention of BPD.

miR34a: a novel small molecule regulator with a big role in bronchopulmonary dysplasia

Preterm infants with bronchopulmonary dysplasia (BPD), characterized by pulmonary inflammation leading to impaired alveolarization and vascular dysregulation, have an increased risk of abnormal lung function in infancy, childhood, and adulthood. These include a heightened risk of pulmonary hypertension, and respiratory illnesses. MicroRNAs (miRNAs) are known to disrupt normal lung development and function by interrupting alveolarization and vascularization resulting in the development of BPD. Among the various miRs involved in BPD, miR34a has been shown to have a significant role in BPD pathogenesis. Targeting miR34a or its downstream targets may be a promising therapeutic intervention for BPD. In this review, we summarize the data on cellular arrest, proliferation, differentiation, epithelial-mesenchymal transition, mitochondrial dysfunction, and apoptosis impacted by miR34a in the development of BPD pulmonary phenotypes while predicting the future perspective of miR34a in BPD.

The role of miR-150 regulates bone cell differentiation and function

BACKGROUND

mir-RNAs play a role in regulating bone homeostasis. In this study we assessed the functional role of mir-RNA 150 in bone homeostasis. We also assess the effects of miR-150 deficiency on osteoblast and osteoclast differentiation and function using in vivo and in vitro approaches.

METHODS

Wild type (WT) (C57BL/6J) and miR-150 KO mice were compared for a variety of parameters. Micro-CT imaging was conducted to quantify trabecular bone mass inferior to the distal growth plate of the femur. Von Kossa staining was performed for osteoblast culture mineralization. RT-qPCR, biochemical analysis and bone histomorphometry were utilized for quantification of relevant genes and serum protein measurements. Differentiation and function of osteoblasts and osteoclasts was performed using primarily cultures and assessed the cell autonomous response of mir-RNA-150 on cell differentiation and function.

RESULTS

Mir-150 exhibited expression in a variety of tissues and increases progressively with age. Through micro-CT imaging, we found that KO mice presented reduced bone mass at 4, 8, and 16 weeks of age compared to WT mice. Furthermore, histomorphometric analysis revealed increased trabecular separation, decreased bone thickness, and decreased osteoblast number in KO compared to WT mice. Mir-150 deficiency also correlated with higher bone resorption, accompanied with significant increases in CTX-1 serum levels, and a decrease in cell apoptotic rate ex vivo. Additionally, miR-150 KO mice showed increased osteoblast differentiation and decreased osteoclastogenesis ex vivo. Luciferase assay showed increased Osteoactivin/GPNMB expression in miR-150 KO osteoblasts compared to WT cells.

CONCLUSION

Our data suggests that miR-150 influences osteoblast and osteoclast functionality and differentiation; specifically, miR-150 serves as a negative regulator for osteoblasts and a positive regulator for osteoclasts by regulating, at least in part, Osteoactivin/GPNMB expression.

Umbilical Cord Blood-Derived Exosomes From Very Preterm Infants With Bronchopulmonary Dysplasia Impaired Endothelial Angiogenesis: Roles of Exosomal MicroRNAs

Premature infants have a high risk of bronchopulmonary dysplasia (BPD), which is characterized by abnormal development of alveoli and pulmonary vessels. Exosomes and exosomal miRNAs (EXO-miRNAs) from bronchoalveolar lavage fluid are involved in the development of BPD and might serve as predictive biomarkers for BPD. However, the roles of exosomes and EXO-miRNAs from umbilical cord blood of BPD infants in regulating angiogenesis are yet to be elucidated. In this study, we showed that umbilical cord blood-derived exosomes from BPD infants impaired angiogenesis in vitro. Next-generation sequencing of EXO-miRNAs from preterm infants without (NBPD group) or with BPD (BPD group) uncovered a total of 418 differentially expressed (DE) EXO-miRNAs. These DE EXO-miRNAs were primarily enriched in cellular function-associated pathways including the PI3K/Akt and angiogenesis-related signaling pathways. Among those EXO-miRNAs which are associated with PI3K/Akt and angiogenesis-related signaling pathways, BPD reduced the expression of hsa-miR-103a-3p and hsa-miR-185-5p exhibiting the most significant reduction (14.3% and 23.1% of NBPD group, respectively); BPD increased hsa-miR-200a-3p expression by 2.64 folds of the NBPD group. Furthermore, overexpression of hsa-miR-103a-3p and hsa-miR-185-5p in normal human umbilical vein endothelial cells (HUVECs) significantly enhanced endothelial cell proliferation, tube formation, and cell migration, whereas overexpressing hsa-miR-200a-3p inhibited these cellular responses. This study demonstrates that exosomes derived from umbilical cord blood of BPD infants impair angiogenesis, possibly via DE EXO-miRNAs, which might contribute to the development of BPD.

SIRT1-Related Signaling Pathways and Their Association With Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic and debilitating disease that can exert serious and overwhelming effects on the physical and mental health of premature infants, predominantly due to intractable short- and long-term complications. Oxidative stress is one of the most predominant causes of BPD. Hyperoxia activates a cascade of hazardous events, including mitochondrial dysfunction, uncontrolled inflammation, reduced autophagy, increased apoptosis, and the induction of fibrosis. These events may involve, to varying degrees, alterations in SIRT1 and its associated targets. In the present review, we describe SIRT1-related signaling pathways and their association with BPD. Our intention is to provide new insights into the molecular mechanisms that regulate BPD and identify potential therapeutic targets for this debilitating condition.

Targeting Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension (BPD-PH): Potential Role of the FGF Signaling Pathway in the Development of the Pulmonary Vascular System

More than 50 years after the first description of Bronchopulmonary dysplasia (BPD) by Northway, this chronic lung disease affecting many preterm infants is still poorly understood. Additonally, approximately 40% of preterm infants suffering from severe BPD also suffer from Bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH), leading to a significant increase in total morbidity and mortality. Until today, there is no curative therapy for both BPD and BPD-PH available. It has become increasingly evident that growth factors are playing a central role in normal and pathologic development of the pulmonary vasculature. Thus, this review aims to summarize the recent evidence in our understanding of BPD-PH from a basic scientific point of view, focusing on the potential role of Fibroblast Growth Factor (FGF)/FGF10 signaling pathway contributing to disease development, progression and resolution.

FoxF1 protects rats from paraquat-evoked lung injury following HDAC2 inhibition via the microRNA-342/KLF5/IκB/NF-κB p65 axis

PURPOSE

Forkhead box f1 (FoxF1), a transcription factor, was implicated in lung development. However, the molecular mechanism of FoxF1 in lung injury, specifically in injury caused by paraquat (PQ), one of the most frequently used herbicides, is unknown. Accordingly, we performed this study to investigate whether FoxF1 attenuates PQ-induced lung injury and to determine the possible mechanism.

METHODS

We used PQ-treated Beas-2B cells to measure the expression of FoxF1. Later, ChIP-qPCR was applied to detect the levels of histone acetylation in cells, followed by the validation of the relationship between histone deacetylase-2 (HDAC2) and FoxF1. Subsequently, the correlation between FoxF1 and microRNA (miR)-342 and the downstream mechanism of miR-342 were evaluated by bioinformatics analysis. The apoptosis and the content of reactive oxygen species (ROS) in PQ-treated cells were detected to evaluate the roles of HDAC2, FoxF1 and miR-342 in vitro. Finally, a rat model was developed to evaluate the effects of HDAC2, miR-342 and Krüppel-like factor 5 (KLF5) on PQ-induced lung injury in vivo.

RESULTS

PQ treatment significantly enhanced FoxF1 promoter deacetylation, thereby inhibiting FoxF1 expression. After inhibition of HDAC2 activity, apoptosis and oxidative stress induced by PQ were significantly reversed. Nevertheless, further inhibition of miR-342 or overexpression of KLF5 promoted apoptosis and oxidative stress induced by PQ, and IκB/NF-κB p65 signaling was significantly activated after PQ treatment.

CONCLUSION

PQ treatment inhibited miR-342 expression by promoting HDAC2-induced deacetylation of the FoxF1 promoter, thereby promoting KLF5 expression and the IκB/NF-κB p65 signaling activation, and finally exacerbating PQ-induced lung injury in rats.

Glycoprotein nonmetastatic melanoma protein B: A key mediator and an emerging therapeutic target in autoimmune diseases

The glycoprotein nonmetastatic melanoma protein B (GPNMB, also known as osteoactivin) is highly expressed in many cell types and regulates the homeostasis in various tissues. In different physiological contexts, it functions as a melanosome-associated protein, membrane-bound surface receptor, soluble ligand, or adhesion molecule. Therefore, GPNMB is involved in cell differentiation, migration, inflammation, metabolism, and neuroprotection. Because of its various involvement in different physiological conditions, GPNMB has been implicated in many diseases, including cancer, neurological disorders, and more recently immune-mediated diseases. This review summarizes the regulation and function of GPNMB in normal physiology, and discusses the involvement of GPNMB in disease conditions with a particular focus on its potential role and therapeutic implications in autoimmunity.

Extracellular vesicle miRNA-21 is a potential biomarker for predicting chronic lung disease in premature infants

Premature infants are often exposed to positive pressure ventilation and supplemental oxygen, which leads to the development of chronic lung disease (CLD). There are currently no standard serum biomarkers used for prediction or early detection of patients who go on to develop CLD. MicroRNAs (miRNAs) are a novel class of naturally occurring, short, noncoding substances that regulate gene expression at the posttranscriptional level and cause translational inhibition and/or mRNA degradation and present in body fluids packaged in extracellular vesicles (EVs), rendering them remarkably stable. Our aim was to evaluate miRNAs identified in serum EVs of premature infants as potential biomarkers for CLD. Serum EVs were extracted from premature infants at birth and on the 28th day of life (DOL). Using a human miRNA array, we identified 62 miRNAs that were universally expressed in CLD patients and non-CLD patients. Of the 62 miRNAs, 59 miRNAs and 44 miRNAs were differentially expressed on DOL0 and DOL28 in CLD and non-CLD patients, respectively. Of these miRNAs, serum EV miR-21 was upregulated in CLD patients on DOL28 compared with levels at birth and downregulated in non-CLD patients on DOL28 compared with levels at birth. In neonatal mice exposed to hyperoxia for 7days, as a model of CLD, five miRNAs (miR-34a, miR-21, miR-712, miR-682, and miR-221) were upregulated, and 7 miRNAs (miR-542-5p, miR-449a, miR-322, miR-190b, miR-153, miR-335-3p, miR-377) were downregulated. MiR-21 was detected as a common miRNA that changed in CLD patients and in the hyperoxia exposed mice. We conclude that EV miR-21 may be a biomarker of CLD.

Mitochondrial Fission-Mediated Lung Development in Newborn Rats With Hyperoxia-Induced Bronchopulmonary Dysplasia With Pulmonary Hypertension

Background: Bronchopulmonary dysplasia (BPD) is the most common chronic respiratory disease in premature infants. Oxygen inhalation and mechanical ventilation are common treatments, which can cause hyperoxia-induced lung injury, but the underlying mechanism is not yet understood. Mitochondrial fission is essential for mitochondrial homeostasis. The objective of this study was to determine whether mitochondrial fission (dynamin-related protein 1, Drp1) is an important mediator of hyperoxia lung injury in rats. Methods: The animal model of BPD was induced with high oxygen (80-85% O₂). Pulmonary histological changes were observed by hematoxylin-eosin (HE) staining. Pulmonary microvessels were observed by immunofluorescence staining of von Willebrand Factor (vWF). Protein expression levels of Drp1 and p-Drp1 (Ser616) were observed using Western Blot. We used echocardiography to measure pulmonary artery acceleration time (PAT), pulmonary vascular resistance index (PVRi), peak flow velocity of the pulmonary artery (PFVP), pulmonary arteriovenous diameter, and pulmonary vein peak velocity. Mitochondrial division inhibitor-1 (Mdivi-1) was used as an inhibitor of Drp1, and administered through intraperitoneal injection (25 mg/kg). Results: Pulmonary artery resistance of the hyperoxide-induced neonatal rat model of BPD increased after it entered normoxic convalescence. During the critical stage of alveolar development in neonatal rats exposed to high oxygen levels for an extended period, the expression and phosphorylation of Drp1 increased in lung tissues. When Drp1 expression was inhibited, small pulmonary vessel development improved and PH was relieved. Conclusion: Our study shows that excessive mitochondrial fission is an important mediator of hyperoxia-induced pulmonary vascular injury, and inhibition of mitochondrial fission may be a useful treatment for hyperoxia-induced related pulmonary diseases.

Predicting the likelihood of bronchopulmonary dysplasia in premature neonates

Introduction: Bronchopulmonary dysplasia (BPD) is the most common serious pulmonary morbidity in premature infants. Despite ongoing advances in neonatal care, the incidence of BPD has not improved. A potential explanation for this phenomenon is the limited ability for accurate early prediction of the risk of BPD. BPD continues to represent a therapeutic challenge and no single effective therapy exists for this condition. Areas covered: Here, we review risk factors of BPD derived from clinical data, biological fluid biomarkers, respiratory management data, and scientific advancements using 'omics' technologies, and their ability to predict the pathogenesis of BPD in preterm neonates. Risk factors and biomarkers were identified via literature search with a focus on the last 5 years of data. Expert opinion: The most accurate predictive tools utilize risk factors that encompass a variety of categories. Numerous predictive models have been proposed but suffer from a lack of adequate validation. An ideal model should include multiple, easily measurable variables validated across a heterogeneous population. In addition to evaluating recent BPD prediction models, we suggest approaches to enhance future models.

Repeated Exposure to Streptococcus pneumoniae Exacerbates Chronic Obstructive Pulmonary Disease

Streptococcus pneumoniae is commonly found in patients with chronic obstructive pulmonary disease (COPD) and is linked to acute exacerbation of COPD. However, current clinical therapy neglects asymptomatic insidious S. pneumoniae colonization. We studied the roles of repeated exposure to S. pneumoniae in COPD progression using a mouse model. C57BL/6J mice were intranasally inoculated with S. pneumoniae ST262 every 4 weeks with or without cigarette smoke (CS) exposure up to 20 weeks to maintain persistent S. pneumoniae presence in the lower airways. Streptococcus pneumoniae enhanced CS-induced inflammatory cell infiltration at 12 to 20 weeks of exposure. Streptococcus pneumoniae also increased CS-induced release of inflammatory cytokines, including IL-1β, tumor necrosis factor-α, IL-12 (p70), and IL-5 at 20 weeks of exposure. Moreover, a combination of CS and S. pneumoniae caused alveolar epithelial injury, a decline in lung function, and an increased expression of platelet-activating factor receptor and bacterial load. Our results suggest that repeated exposure to S. pneumoniae in lower airways exacerbates CS-induced COPD.

MicroRNA expression profile in retina and choroid in oxygen-induced retinopathy model

Background

Ischemic retinopathies (IRs) are leading causes of visual impairment. They are characterized by an initial phase of microvascular degeneration and a second phase of aberrant pre-retinal neovascularization (NV). microRNAs (miRNAs) regulate gene expression, and a number play a role in normal and pathological NV. But, post-transcriptional modulation of miRNAs in the eye during the development of IRs has not been systematically evaluated.

Aims & methods

Using Next Generation Sequencing (NGS) we profiled miRNA expression in the retina and choroid during vasodegenerative and NV phases of oxygen-induced retinopathy (OIR).

Results

Approximately 20% of total miRNAs exhibited altered expression (up- or down-regulation); 6% of miRNA were found highly expressed in retina and choroid of rats subjected to OIR. During OIR-induced vessel degeneration phase, miR-199a-3p, -199a-5p, -1b, -126a-3p displayed a robust decreased expression (> 85%) in the retina. While in the choroid, miR-152-3p, -142-3p, -148a-3p, -532-3p were upregulated (>200%) and miR-96-5p, -124-3p, -9a-3p, -190b-5p, -181a-1-3p, -9a-5p, -183-5p were downregulated (>70%) compared to controls. During peak pathological NV, miR-30a-5p, -30e-5p and 190b-5p were markedly reduced (>70%), and miR-30e-3p, miR-335, -30b-5p strongly augmented (by up to 300%) in the retina. Whereas in choroid, miR-let-7f-5p, miR-126a-5p and miR-101a-3p were downregulated by (>81%), and miR-125a-5p, let-7e-5p and let-7g-5p were upregulated by (>570%) during NV. Changes in miRNA observed using NGS were validated using qRT-PCR for the 24 most modulated miRNAs. In silico approach to predict miRNA target genes (using algorithms of miRSystem database) identified potential new target genes with pro-inflammatory, apoptotic and angiogenic properties.

Conclusion

The present study is the first comprehensive description of retinal/choroidal miRNAs profiling in OIR (using NGS technology). Our results provide a valuable framework for the characterization and possible therapeutic potential of specific miRNAs involved in ocular IR-triggered inflammation, angiogenesis and degeneration.

MicroRNA-421 inhibition alleviates bronchopulmonary dysplasia in a mouse model via targeting Fgf10

Bronchopulmonary dysplasia (BPD) is a common and refractory disease affecting newborn children and infants with alveolar dysplasia and declined pulmonary function. Several microRNAs (miRNAs) have been found to be differentially expressed in BPD progression. This study further explores the role of miR-421 via fibroblast growth factor 10 (Fgf10) in mice with BPD. A mouse model of BPD was established through the induction of hyperoxia, in which the expression pattern of miR-421 and Fgf10 was identified. Furthermore, adenovirus-packed vectors were injected in mice to intervene miR-421 and Fgf10 expression, including miR-421 mimics or inhibitors, and si-Fgf10 to explore the role of miR-421 and Fgf10 in BPD. The target relationship between miR-421 and Fgf10 was investigated. Inflammatory response and cell apoptosis were observed in the mice, with inflammatory cytokines and apoptosis-related factors detected by applying Reverse transcription quantitative polymerase chain reaction, Western blot analysis, and enzyme-linked immunosorbent assay. Fgf10 was confirmed as a target gene of miR-421. Elevated expression of miR-421 was evident, while Fgf10 was poorly expressed in BPD. upregulation of miR-421 and silence of Fgf10 aggravated inflammatory response in lung tissue and promoted lung cell apoptosis in BPD. The aforementioned alterations could be reversed by downregulation of miR-421. Collectively, inhibition of miR-421 can assist in the development of BPD in mice BPD by upregulating Fgf10. Therefore, the present study provides a probable target for the treatment of BPD.

Lipoxin A4 reduces hyperoxia-induced lung injury in neonatal rats through PINK1 signaling pathway

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in premature infants and is mainly caused by hyperoxia exposure and mechanical ventilation. Alveolar simplification, pulmonary vascular abnormalities and pulmonary inflammation are the main pathological changes in hyperoxic lung injury animals. Lipoxin A4 (LXA4) is an important endogenous lipid that can mediate the regression of inflammation and plays a role in acute lung injury and asthma. The purpose of this study was to evaluate the effects of LXA4 on inflammation and lung function in neonatal rats with hyperoxic lung injury and to explore the mechanism of the PINK1 pathway. After 85% oxygen exposure in newborn rats for 7 days, the BPD model was established. We found that LXA4 could significantly reduce cell and protein infiltration and oxidative stress in rat lungs, improve pulmonary function and alveolar simplification, and promote weight gain. LXA4 inhibited the expression of TNF-α, MCP-1 and IL-1β in serum and BALF from hyperoxic rats. Moreover, we found that LXA4 could reduce the expression of the PINK1 gene and down-regulate the expression of PINK1, Parkin, BNIP3L/Nix and the autophagic protein LC3B.These protective effects of LXA4 could be partially reversed by addition of BOC-2.Thus, we concluded that LXA4 can alleviate the airway inflammatory response, reduce the severity of lung injury and improve lung function in a hyperoxic rat model of BPD partly through the PINK1 signaling pathway.

MicroRNA-30a as a candidate underlying sex-specific differences in neonatal hyperoxic lung injury: implications for BPD

Premature male neonates are at a greater risk of developing bronchopulmonary dysplasia (BPD). The reasons underlying sexually dimorphic outcomes in premature neonates are not known. The role of miRNAs in mediating sex biases in BPD is understudied. Analysis of the pulmonary transcriptome revealed that a large percentage of angiogenesis-related differentially expressed genes are miR-30a targets. We tested the hypothesis that there is differential expression of miR-30a in vivo and in vitro in neonatal human pulmonary microvascular endothelial cells (HPMECs) upon exposure to hyperoxia. Neonatal male and female mice (C57BL/6) were exposed to hyperoxia [95% fraction of inspired oxygen (FiO2), postnatal day ( PND) 1-5] and euthanized on PND 7 and 21. HPMECs (18-24-wk gestation donors) were subjected to hyperoxia (95% O2 and 5% CO2) or normoxia (air and 5% CO2) up to 72 h. miR-30a expression was increased in both males and females in the acute phase ( PND 7) after hyperoxia exposure. However, at PND 21 (recovery phase), female mice showed significantly higher miR-30a expression in the lungs compared with male mice. Female HPMECs showed greater expression of miR-30a in vitro upon exposure to hyperoxia. Delta-like ligand 4 (Dll4) was an miR-30a target in HPMECs and showed sex-specific differential expression. miR-30a increased angiogenic sprouting in vitro in female HPMECs. Lastly, we show decreased expression of miR-30a and increased expression of DLL4 in human BPD lung samples compared with controls. These results support the hypothesis that miR-30a could, in part, contribute to the sex-specific molecular mechanisms in play that lead to the sexual dimorphism in BPD.

MicroRNA-34a Suppresses Autophagy in Alveolar Type II Epithelial Cells in Acute Lung Injury by Inhibiting FoxO3 Expression

Excessive autophagic activity of alveolar type II epithelial (AT-II) cells is one of the main causes of acute lung injury (ALI); however, the underlying molecular mechanism remains to be determined. The microRNAs (miRNAs) are involved with autophagy in many diseases. The objective of this study was therefore to investigate the relationship between the miRNA expression and the autophagic activity of the AT-II cells in the pathogenesis of ALI and its molecular mechanism. A mouse model of ALI and AT-II cell injury was induced using lipopolysaccharide (LPS) in vivo and in vitro, and the expression of miR-34a and the autophagy-related proteins LC3 II/I and p62 were determined. Moreover, the autophagic activity was investigated after miR-34a overexpression and inhibition. The effects of miR-34a on its target gene, FoxO3, in regulating autophagic activity in AT-II cells were also determined. LPS induced autophagic activity and increased the expression of miR-34a in lung tissues and in AT-II cells. The in vitro results showed that the upregulation of miR-34a suppressed, whereas the inhibition of miR-34a promoted, autophagy in AT-II cells. Moreover, miR-34a could directly bind to the 3'-untranslated region of the autophagy-related gene, FoxO3, to decrease its expression. In addition, the knockdown of FoxO3 expression inhibited the autophagic activity in AT-II cells. Together, this study suggested that miR-34a might suppress the excessive autophagic activity in AT-II cells via targeting FoxO3 to reduce the damage of LPS-induced ALI.

Lung microRNA deregulation associated with impaired alveolarization in rats after intrauterine growth restriction

Intrauterine growth restriction (IUGR) was recently described as an independent risk factor of bronchopulmonary dysplasia, the main respiratory sequelae of preterm birth. We previously showed impaired alveolarization in rat pups born with IUGR induced by a low-protein diet (LPD) during gestation. We conducted a genome-wide analysis of gene expression and found the involvement of several pathways such as cell adhesion. Here, we describe our unbiased microRNA (miRNA) profiling by microarray assay and validation by qPCR at postnatal days 10 and 21 (P10 and P21) in lungs of rat pups with LPD-induced lung-alveolarization disorder after IUGR. We identified 13 miRNAs with more than two-fold differential expression between control lungs and LPD-induced IUGR lungs. Validated and predicted target genes of these miRNAs were related to “tissue repair” at P10 and “cellular communication regulation” at P21. We predicted the deregulation of several genes associated with these pathways. Especially, E2F3, a transcription factor involved in cell cycle control, was expressed in developing alveoli, and its mRNA and protein levels were significantly increased at P21 after IUGR. Hence, IUGR affects the expression of selected miRNAs during lung alveolarization. These results provide a basis for deciphering the mechanistic contributions of IUGR to impaired alveolarization.

Hyperoxia causes miR-34a-mediated injury via angiopoietin-1 in neonatal lungs

Hyperoxia-induced acute lung injury (HALI) is a key contributor to the pathogenesis of bronchopulmonary dysplasia (BPD) in neonates, for which no specific preventive or therapeutic agent is available. Here we show that lung micro-RNA (miR)-34a levels are significantly increased in lungs of neonatal mice exposed to hyperoxia. Deletion or inhibition of miR-34a improves the pulmonary phenotype and BPD-associated pulmonary arterial hypertension (PAH) in BPD mouse models, which, conversely, is worsened by miR-34a overexpression. Administration of angiopoietin-1, which is one of the downstream targets of miR34a, is able to ameliorate the BPD pulmonary and PAH phenotypes. Using three independent cohorts of human samples, we show that miR-34a expression is increased in type 2 alveolar epithelial cells in neonates with respiratory distress syndrome and BPD. Our data suggest that pharmacologic miR-34a inhibition may be a therapeutic option to prevent or ameliorate HALI/BPD in neonates.

Glycoprotein NMB: an Emerging Role in Neurodegenerative Disease

Neurodegeneration is characterized by severe neuronal loss leading to the cognitive and physical impairments that define various neurodegenerative diseases. Neuroinflammation is one hallmark of neurodegenerative diseases and can ultimately contribute to disease progression. Increased inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1β (IL-1 β), and tumor necrosis factor-α (TNF-α) are associated with Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Unfortunately, current therapeutic options lack ability to stop or effectively slow progression of these diseases and are primarily aimed at alleviating symptoms. Thus, it is crucial to discover novel treatment candidates for neurodegenerative diseases. Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a type-I transmembrane glycoprotein first identified in a melanoma cell line. GPNMB augments bone mineral deposition by stimulating osteoblast differentiation. Aside from its anabolic function in the bone, emerging evidence suggests that GPNMB has anti-inflammatory and reparative functions. GPNMB has also been demonstrated to be neuroprotective in an animal model of ALS, cerebral ischemia, and other disease models. Given these discoveries, GPNMB should be investigated as a potential therapeutic option for multiple neurodegenerative diseases.

MicroRNAs in mucosal inflammation

Of the total human body's surface, the majority is internal surface, belonging to the lungs (100 m²) and intestinal tract (400 m²). In comparison, the external surface area, belonging to the skin, comprises less than 1% (2 m²). Continuous exposure of the mucosal surface to external factors (e.g., pathogens, food particles) requires tight regulation to maintain homeostasis. MicroRNAs (miRNAs) have gained noticeable attention as playing important roles in maintaining the steady-state of tissues by modulating immune functions and inflammatory responses. Accordingly, associations have been found between miRNA expression levels and human health conditions and diseases. These findings have important implications in inflammatory diseases involving pulmonary and intestinal mucosa, such as acute lung injury or inflammatory bowel disease. In this review, we highlight the known biology of miRNAs and discuss the role of miRNAs in modulating mucosal defense and homeostasis. Additionally, we discuss miRNAs serving as potential therapeutic targets to treat immunological conditions, particularly mucosal inflammation.

Targeting GPNMB with glembatumumab vedotin: Current developments and future opportunities for the treatment of cancer

GPNMB has emerged as an immunomodulator and an important positive mediator of tumor progression and metastasis in numerous solid cancers. Tumor intrinsic GPNMB-mediated effects on cellular signaling, coupled with the ability of GPNMB to influence the primary tumor and metastatic microenvironments in a non-cell autonomous fashion, combine to augment malignant cancer phenotypes. In addition, GPNMB is often overexpressed in a variety of cancers, making it an attractive therapeutic target. In this regard, glembatumumab vedotin, an antibody-drug conjugate (ADC) that targets GPNMB, is currently in clinical trials as a single agent in multiple cancers. In this review, we will describe the physiological functions of GPNMB in normal tissues and summarize the processes through which GPNMB augments tumor growth and metastasis. We will review the pre-clinical and clinical development of glembatumumab vedotin, evaluate on-going clinical trials, explore emerging opportunities for this agent in new disease indications and discuss exciting possibilities for this ADC in the context of combination therapies.

S-Nitrosoglutathione Attenuates Airway Hyperresponsiveness in Murine Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is characterized by lifelong obstructive lung disease and profound, refractory bronchospasm. It is observed among survivors of premature birth who have been treated with prolonged supplemental oxygen. Therapeutic options are limited. Using a neonatal mouse model of BPD, we show that hyperoxia increases activity and expression of a mediator of endogenous bronchoconstriction, S-nitrosoglutathione (GSNO) reductase. MicroRNA-342-3p, predicted in silico and shown in this study in vitro to suppress expression of GSNO reductase, was decreased in hyperoxia-exposed pups. Both pretreatment with aerosolized GSNO and inhibition of GSNO reductase attenuated airway hyperresponsiveness in vivo among juvenile and adult mice exposed to neonatal hyperoxia. Our data suggest that neonatal hyperoxia exposure causes detrimental effects on airway hyperreactivity through microRNA-342-3p–mediated upregulation of GSNO reductase expression. Furthermore, our data demonstrate that this adverse effect can be overcome by supplementing its substrate, GSNO, or by inhibiting the enzyme itself. Rates of BPD have not improved over the past two decades; nor have new therapies been developed. GSNO-based therapies are a novel treatment of the respiratory problems that patients with BPD experience.

Early injury of the neonatal lung contributes to premature lung aging: a hypothesis

Chronic lung disease of the newborn, also known as bronchopulmonary dysplasia (BPD), is the most common chronic lung disease in early infancy and results in an increased risk for long-lasting pulmonary impairment in the adult. BPD develops upon injury of the immature lung by oxygen toxicity, mechanical ventilation, and infections which trigger sustained inflammatory immune responses and extensive remodeling of the extracellular matrix together with dysregulated growth factor signaling. Histopathologically, BPD is characterized by impaired alveolarization, disrupted vascular development, and saccular wall fibrosis. Here, we explore the hypothesis that development of BPD involves disturbance of conserved pathways of molecular aging that may contribute to premature aging of the lung and an increased susceptibility to chronic lung diseases in adulthood.

MiR-196a regulates heme oxygenase-1 by silencing Bach1 in the neonatal mouse lung

In the lung, heme oxygenase-1 (HO-1) is developmentally regulated, with its highest expression in the first days of life. In addition, neonatal mice have limited HO-1 induction in hyperoxia compared with adults. However, few reports have addressed the functional effect of microRNAs (miRNAs) in the regulation of HO-1 in vivo. The aims of the present study were to characterize changes in lung miRNA expression during postnatal development and in response to hyperoxic exposure, and to identify miRNAs that target lung HO-1 gene expression. Neonatal (<12 h old) and adult (2 mo old) mice were exposed to room air or hyperoxia (95% oxygen) for 72 h. TaqMan low-density array rodent miRNA assays were used to calculate miRNA expression changes between control and hyperoxia groups in neonatal and adult lungs. In neonates, we identified miR-196a, which binds to the 3'-untranslated region of the transcriptional repressor BTB and CNC homology 1 (Bach1) and regulates its expression, and subsequently leads to higher levels of lung HO-1 mRNA compared with levels in adults. Despite the increase at baseline, miR-196a was degraded in hyperoxia resulting in limited HO-1 induction in neonatal mice lungs. Furthermore, the developmental differences in lung HO-1 gene expression can be explained in part by the variation in miRNA-196a and its effect on Bach1. This report is the first to show developmental differences in lung miR-196a and its effect on Bach1 and HO-1 expression at baseline and in hyperoxia.

MicroRNA in late lung development and bronchopulmonary dysplasia: the need to demonstrate causality

MicroRNA are emerging as powerful regulators of cell differentiation and tissue and organ development. Several microRNA have been described to play a role in branching morphogenesis, a key step in early lung development. However, considerably less attention has been paid to microRNA as regulators of the process of secondary septation, which drives lung alveolarization during late lung development. Secondary septation is severely perturbed in bronchopulmonary dysplasia (BPD), a common complication of preterm birth characterized by blunted alveolarization. A number of studies to date have reported microRNA microarray screens in animal models of BPD; however, only two studies have attempted to demonstrate causality. Although the expression of miR-150 was altered in experimental BPD, a miR-150^−/− knockout mouse did not exhibit appreciable protection in a BPD animal model. Similarly, while the expression of miR-489 in the lung was reduced in clinical and experimental BPD, antagomiR and over-expression approaches could not validate a role for miR-489 in the impaired alveolarization associated with experimental BPD. This mini-review aims to highlight microRNA that have been revealed by multiple microarray studies to be potential causal players in normal and pathological alveolarization. Additionally, the challenges faced in attempting to demonstrate a causal role for microRNA in lung alveolarization are discussed. These include the tremendous variability in the animal models employed, and the limitations and advantages offered by the available tools, including antagomiRs and approaches for the validation of a specific microRNA-mRNA interaction during lung alveolarization.

MicroRNA Regulation of Acute Lung Injury and Acute Respiratory Distress Syndrome

The acute respiratory distress syndrome (ARDS), a severe form of acute lung injury (ALI), is a very common condition associated with critically ill patients, which causes substantial morbidity and mortality worldwide. Despite decades of research, effective therapeutic strategies for clinical ALI/ARDS are not available. In recent years, microRNAs (miRNAs), small non-coding molecules have emerged as a major area of biomedical research as they post-transcriptionally regulate gene expression in diverse biological and pathological processes, including ALI/ARDS. In this context, this present review summarizes a large body of evidence implicating miRNAs and their target molecules in ALI/ARDS originating largely from studies using animal and cell culture model systems of ALI/ARDS. We have also focused on the involvement of miRNAs in macrophage polarization, which play a critical role in regulating the pathogenesis of ALI/ARDS. Finally, the possible future directions that might lead to novel therapeutic strategies for the treatment of ALI/ARDS are also reviewed. J. Cell. Physiol. 231: 2097-2106, 2016. © 2016 Wiley Periodicals, Inc.

miR-185 mediates lung epithelial cell death after oxidative stress

Lung epithelial cell death is a prominent feature involved in the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Hyperoxia-induced ALI is an established animal model mimicking human ARDS. Small noncoding RNAs such as microRNAs (miRNAs) have potent physiological and pathological functions involving multiple disease processes. Emerging interests focus on the potential of miRNAs to serve as novel therapeutic targets and diagnostic biomarkers. We found that hyperoxia highly induces miR-185 and its precursor in human lung epithelial cells in a time-dependent manner, and this observation is confirmed using mouse primary lung epithelial cells. The hyperoxia-induced miR-185 is mediated by reactive oxygen species. Furthermore, histone deacetylase 4 (HDAC4) locates in the promoter region of miR-185. We found that hyperoxia suppresses HDAC4 specifically in a time-dependent manner and subsequently affects histone deacetylation, resulting in an elevated miR-185 transcription. Using MC1586, an inhibitor of class IIa HDACs, we showed that inhibition of class IIa HDACs upregulates the expression of miR-185, mimicking the effects of hyperoxia. Functionally, miR-185 promotes hyperoxia-induced lung epithelial cell death through inducing DNA damage. We confirmed functional roles of miR-185 using both the loss- and gain-of-function approaches. Moreover, multiple 14-3-3δ pathway proteins are highly attenuated by miR-185 in the presence of hyperoxia. Taken together, hyperoxia-induced miR-185 in lung epithelial cells contributes to oxidative stress-associated epithelial cell death through enhanced DNA damage and modulation of 14-3-3δ pathways.

Wnt5a reverses the inhibitory effect of hyperoxia on transdifferentiation of alveolar epithelial type II cells to type I cells

Transdifferentiation of alveolar epithelial type II cells (AECIIs) to type I cells (AECIs) is critical for reestablishment and maintenance of an intact alveolar epithelium. However, this process is frequently destroyed by hyperoxia treatment, which is commonly used in respiratory distress syndrome therapy in preterm infants. Wnt5a is considered to participate in this physiopathologic process, but the clear mechanisms still need to be further investigated. In this study, preterm rats and primary rat AECIIs were exposed to hyperoxia. Hematoxylin and eosin staining was used to examine the histological changes of the lungs. Real-time PCR and western blotting were used to examine Wnt5a expression and biomarkers of AECII and AECI expression. Immunohistochemistry and immunofluorescence were also used to determine the expression and location of selected biomarkers. Furthermore, AECIIs transfected with Wnt5a gene and exogenous Wnt5a were used to examine whether Wnt5a contributes to the transdifferentiation of AECIIs to AECIs. Results showed that hyperoxia inhibited the transdifferentiation of AECIIs to AECIs in vitro, which is represented by biomarkers of two types of cell that remained unchanged. In addition, Wnt5a protein expression was found to be decreased after hyperoxia exposure in vitro and in vivo. Furthermore, both the overexpression of Wnt5a and exogenous Wnt5a addition blocked the inhibitory effect of hyperoxia in vitro. In conclusion, our results suggest that the transdifferentiation of AECIIs to AECIs is impaired by hyperoxia, and this process may be associated with Wnt5a downregulation. Targeting Wnt5a may have the potential for the therapy of lung injury in preterm infants induced by hyperoxia.

MicroRNA expression profiles and target prediction in neonatal Wistar rat lungs during the development of bronchopulmonary dysplasia

In this study, we investigated the mechanisms through which microRNAs (miRNAs or miRs) regulate lung development after birth, as well as the role of miRNAs in the development of bronchopulmonary dysplasia (BPD). For this purpose, a total of 90 neonatal Wistar rats were randomly and equally assigned to either a model group or a control group. On postnatal days 3, 7 and 14, the lung tissues were collected for histological analysis to determine morphological changes. The expression levels of proliferating cell nuclear antigen (PCNA) and platelet endothelial cell adhesion molecule-1 (PECAM-1, also known as CD31) were measured by RT-qPCR and western blot analysis. A miRCURY™ LNA array was employed to screen for differentially expressed miRNAs, and the possible target genes of those miRNAs were predicted. Our results revealed that, compared with the control group, the following changes induced by hyperoxia were observed in the model group over time: a decrease in the number, but an increase in the size of the alveoli, and a decrease in the number of secondary septa formed. In the model group, from postnatal days 3–14, the mRNA and protein expression levels of PCNA and CD31 were significantly lower than those in the control group. The differentially expressed miRNAs between the 2 groups were identified on days 3, 7 and 14 after birth. Possible target genes were identified for 32 differentially expressed miRNAs. Taken together, these findings suggest that during the development of BPD, an alveolarization disorder with microvascular dysplasia co-exists with the differential expression of certain miRNAs during the different stages of alveolar development in a neonatal rat model of hyperoxia-induced BPD. This indicates that miRNAs may participate in the occurrence and development of BPD.

Wnt3a Mediates the Inhibitory Effect of Hyperoxia on the Transdifferentiation of AECIIs to AECIs

The aim of this study is to investigate the effect of Wnt3a in the transdifferentiation of type II alveolar epithelial cells (AECIIs) to type I alveolar epithelial cells (AECIs) under hyperoxia condition. In the in vivo study, preterm rats were exposed in hyperoxia for 21 days. In the in vitro study, primary rat AECIIs were subjected to a hyperoxia and normoxia exposure alternatively every 24 hr for 7 days. siRNA-mediated knockout of Wnt3a and exogenous Wnt3a were used to investigate the effect of Wnt3a on transdifferentiation of AECIIs to AECIs. Wnt5a-overexpressed AECIIs were also used to investigate whether Wnt3a could counteract the effect of Wnt5a. The results showed that hyperoxia induced alveolar damage in the lung of preterm born rats, as well as an increased expression of Wnt3a and nuclear accumulation of β-catenin. In addition, Wnt3a/β-catenin signaling was activated in isolated AECIIs after hyperoxia exposure. Wnt3a knockout blocked the inhibition of the transdifferentiation induced by hyperoxia, and Wnt3a addition exacerbated this inhibition. Furthermore, Wnt3a addition blocked the transdifferentiation-promoting effect of Wnt5a in hyperoxia-exposed Wnt5a-overexpressed AECIIs. In conclusion, our results demonstrate that the activated Wnt3a/β-catenin signal may be involved in the hyperoxia-induced inhibition of AECIIs' transdifferentiation to AECIs.

Characterization of miRNA processing machinery in the embryonic chick lung

Lung development is a very complex process that relies on the interaction of several signaling pathways that are controlled by precise regulatory mechanisms. Recently, microRNAs (miRNAs), small non-coding regulatory RNAs, have emerged as new players involved in gene expression regulation controlling several biological processes, such as cellular differentiation, apoptosis and organogenesis, in both developmental and disease processes. Failure to correctly express some specific miRNAs or a component of their biosynthetic machinery during embryonic development is disastrous, resulting in severe abnormalities. Several miRNAs have already been identified as modulators of lung development. Regarding the spatial distribution of the processing machinery of miRNAs, only two of its members (dicer1 and argonaute) have been characterized. The present work characterizes the expression pattern of drosha, dgcr8, exportin-5 and dicer1 in early stages of the embryonic chick lung by whole mount in situ hybridization and cross-section analysis. Overall, these genes are co-expressed in dorsal and distal mesenchyme and also in growing epithelial regions. The expression pattern of miRNA processing machinery supports the previously recognized regulatory role of this mechanism in epithelial and mesenchymal morphogenesis.

Role of microRNA-150 and glycoprotein nonmetastatic melanoma protein B in angiogenesis during hyperoxia-induced neonatal lung injury

Glycoprotein nonmetastatic melanoma protein B (GPNMB), a transmembrane protein, has been reported to have an important role in tissue repair and angiogenesis. Recently, we have demonstrated that hyperoxia exposure down-regulates microRNA (miR)-150 expression and concurrent induction of its target gene, GPNMB, in neonatal rat lungs. This study aimed to test the hypothesis that soluble GPNMB (sGPNMB) promotes angiogenesis in the hyperoxic neonatal lungs. Wild-type (WT) or miR-150 knockout (KO) neonates, exposed to 95% O2 for 3, 6, and 10 days, were evaluated for lung phenotypes, GPNMB protein expression in the lungs, and sGPNMB levels in the bronchoalveolar lavage. Angiogenic effects of sGPNMB were examined both in vitro and in vivo. After a 6-day exposure, similar analyses were performed in WT and miR-150 KO neonates during recovery at 7, 14, and 21 days. miR-150 KO neonates displayed an increased capillary network, decreased inflammation, and less alveolar damage compared with WT neonates after hyperoxia exposure. The early induction of GPNMB and sGPNMB were found in miR-150 KO neonates. The recombinant GPNMB, which contained a soluble portion of GPNMB, promoted endothelial tube formation in vitro and enhanced angiogenesis in vivo. The increased capillaries in the hyperoxic lungs of miR-150 KO neonates appeared dysmorphic. They were abnormally enlarged in size and occasionally laid at subepithelial regions in the alveoli. However, the lung architecture returned to normal during recovery, suggesting that abnormal vascularity during hyperoxia does not affect postnatal lung development. GPNMB plays an important role in angiogenesis during hyperoxia injury. Treatment with GPNMB may offer a novel therapeutic approach in reducing pathologic complications in bronchopulmonary dysplasia.

Epigenetic contributions to the developmental origins of adult lung disease

Perinatal insults, including intrauterine growth restriction, preterm birth, maternal exposure to toxins, or dietary deficiencies produce deviations in the epigenome of lung cells. Occurrence of perinatal insults often coincides with the final stages of lung development. The result of epigenome disruptions in response to perinatal insults during lung development may be long-term structural and functional impairment of the lung and development of lung disease. Understanding the contribution of epigenetic mechanisms to life-long lung disease following perinatal insults is the focus of the developmental origins of adult lung disease field. DNA methylation, histone modifications, and microRNA changes are all observed in various forms of lung disease. However, the perinatal contribution to such epigenetic mechanisms is poorly understood. Here we discuss the developmental origins of adult lung disease, the interplay between perinatal events, lung development and disease, and the role that epigenetic mechanisms play in connecting these events.

Identification of most stable endogenous control genes for microRNA quantification in the developing mouse lung

MicroRNAs (miRNAs) are endogenous small non coding RNAs acting as negative regulators. miRNA are involved in lung development and pulmonary diseases. Measurement of their levels by qPCR is directly influenced by the stability of normalization gene(s), which can be affected by the experimental conditions. The developing lung is a changing tissue and one normalization gene showing stability on one developmental day may be modulated over time. Moreover, some developmental events are affected by sex, which also has to be considered. In this study, we compared stability of five putative control genes in the lung between sexes from the pseudoglandular to the alveolar stages and in adult lungs. Expression of sno135, sno142, sno202, sno234, and sno251 was studied by qPCR in male and female lung samples collected at seven time points from GD 15.5 to PN 30. Cq values of sno251 showed the highest variation across the different developmental stages, while sno234 was the most stable gene. Gene expression stability was studied by geNorm, NormFinder and BestKeeper. Our data showed that ranking of genes based on expression stability changed according to developmental time and sex. sno135/sno234 and sno142/sno234 were proposed as best combinations of normalization genes when both sexes and all the studied developmental stages are considered. Normalization of let7-a RNA levels with different pairs of control genes proposed by geNorm and NormFinder gave similar data, while the use of less stable genes introduced a statistically significant difference on PN 0. In conclusion, variations in stability of normalization gene expression are observed over time and according to sex during lung development. Best pairs of normalization genes are presented for specific developmental stages, and for the period extending from the pseudoglandular to the alveolar stages. The use of normalization genes selected for their expression stability is essential in lung development studies.

MicroRNA and mRNA expression profiling in rat acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is characterized by pulmonary epithelial injury and extensive inflammation of the pulmonary parenchyma. Systematic analyses of microRNA (miRNA) and mRNA expression profiling in ARDS provide insights into understanding of molecular mechanisms of the pathogenesis of ARDS. The objective of this study was to identify miRNA and mRNA interactions in a rat model of ARDS by combining miRNA and mRNA microarray analyses.

Methods

Rat model of ARDS was induced by saline lavage and mechanical ventilation. The expression profiles of both mRNAs and miRNAs in rat ARDS model were performed by microarray analyses. Microarray data were further verified by quantitative RT-PCR. Functional annotation on dys-regulated mRNAs and miRNAs was carried out by bioinformatics analysis.

Results

The expression of 27 miRNAs and 37 mRNAs were found to be significantly changed. The selected miRNAs and genes were further verified by quantitative real-time PCR. The down-regulated miRNAs included miR-24, miR-26a, miR-126, and Let-7a, b, c, f. The up-regulated miRNAs were composed of miR-344, miR-346, miR-99a, miR-127, miR-128b, miR-135b, and miR-30a/b. Gene ontology and functional annotation analyses indicated that up-regulated mRNAs, such as Apc, Timp1, and Sod2, were involved in the regulation of apoptosis. Bioinformatics analysis showed the inverse correlation of altered miRNAs with the expression of their predicted target mRNAs. While Sod2 was inversely correlated with Let-7a, b, c, f., Ebf1 and Apc were inversely correlated with miR-24 and miR-26a, respectively. miR-26a, miR-346, miR-135b, miR-30a/b, miR-344, and miR-18a targeted multiple altered mRNAs. Gabrb1, Sod2, Eif2ak1, Fbln5, and Tspan8 were targeted by multiple altered miRNAs.

Conclusion

The expressions of miRNAs and mRNAs were altered in a rat model of ARDS. The identified miRNA-mRNA pairs may play critical roles in the pathogenesis of ARDS.

Use of hyperbaric oxygenation in neonatal patients: a pilot study of 8 patients

This article presents a pilot study to determine the value of hyperbaric oxygenation (HBO₂) in the acute management of neonatal hypoxia (hypoxic ischemic encephalopathy) and necrotizing enterocolitis. Neonates with hypoxic-ischemic encephalopathy and NE were treated in a Sechrist monoplace chamber. Electroencephalogram, evoked potential, ophthalmic evaluation, ultrasonograph, laboratory exams, and radiographs were obtained before and after HBO₂. Treatment protocol was 2.0 atm abs/45 minutes. Preventive myringotomies were conducted in all patients. A follow-up was done at 3 and 6 months. All patients (n = 8) were ventilator-dependent and required bag-valve-mask ventilation by a neonatologist during the treatment. All showed a resolution after HBO₂. There was also a dramatic improvement (P < .05) in hemoglobin, hematocrit, total proteins, serum sodium, triglycerides, and pH. There were favorable changes in all other studies although they did not meet statistical significance. There was a marked reduction of the morbidity and mortality. There were no adverse effects on the ophthalmologic or Central Nervous System. When used promptly, HBO₂ can modify the local and systemic inflammatory response caused by intestinal inflammation or cerebral or systemic hypoxia. It helps to preserve the marginal tissue and recover the ischemic and metabolic penumbra. This pilot study suggests that HBO₂ could be a safe and effective treatment in the acute management of neonatal necrotizing enterocolitis or hypoxic ischemic encephalopathy. There is a need for a prospective, randomized, controlled, and double-blinded study to determine the real use of HBO₂ in these cases.

microRNAs mediate oleic acid-induced acute lung injury in rats using an alternative injury mechanism

Intravenous (IV) infusion of oleic acid (OA) distributes OA microemboli in the pulmonary capillaries, which results in severe vascular congestion, hemorrhage vascular congestion, interstitial edema, intravascular coagulation and bleeding. The immune response to acute lung injury (ALI) is known to be associated with rapid and widespread changes in microRNA (miRNA) expression in the lung. The present study of a model of rat lung injury aimed to investigate how the lung miRNA profile changes to mediate ALI. For the induction of ALI, OA (200 µl/kg) suspended in 20% ethyl alcohol was injected through the tail vein for 20 min. Lung tissue samples were acquired at 3, 6 and 24 h, and miRNA microarray and quantitative polymerase chain reaction were performed using these samples. The activation of phosphatase and tensin homolog (PTEN), protein kinase B (Akt), extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK) were analyzed by western blot analysis. There were 75 miRNAs that demonstrated >1.5‑fold changes in expression levels. miR-101a was highly upregulated at 3 h. miR-21 was upregulated in the OA group throughout the 24 h following OA challenge. miR-1 was the most downregulated miRNA at 24 h. In order to examine the expression levels of PTEN and Akt as targets of miR-21, western blot analysis was performed. At 3 h, the levels of PTEN were attenuated in the OA group as compared with those in the control group; however, p-Akt/Akt levels were increased at 3 h for the OA group. PTEN and p-Akt/Akt were significantly higher in the OA group at 3 h and were rapidly decreased at 6 h. The immunohistochemical stain of α-smooth muscle actin in the bronchial and alveolar wall increased 24 h after OA‑induced ALI. These results indicated that the profile of miRNAs dynamically changed throughout the OA-induced ALI process, and mitogen-activated protein kinase activation, PTEN/Akt pathway alteration and smooth muscle actin activation were observed in this ALI model.

Establishing reliable miRNA-cancer association network based on text-mining method

Associating microRNAs (miRNAs) with cancers is an important step of understanding the mechanisms of cancer pathogenesis and finding novel biomarkers for cancer therapies. In this study, we constructed a miRNA-cancer association network (miCancerna) based on more than 1,000 miRNA-cancer associations detected from millions of abstracts with the text-mining method, including 226 miRNA families and 20 common cancers. We further prioritized cancer-related miRNAs at the network level with the random-walk algorithm, achieving a relatively higher performance than previous miRNA disease networks. Finally, we examined the top 5 candidate miRNAs for each kind of cancer and found that 71% of them are confirmed experimentally. miCancerna would be an alternative resource for the cancer-related miRNA identification.