Changes in microRNA and mRNA expression with differentiation of human bronchial epithelial cells

Analysis of miRNAs in Osteogenesis imperfecta Caused by Mutations in COL1A1 and COL1A2: Insights into Molecular Mechanisms and Potential Therapeutic Targets

Osteogenesis imperfecta (OI) is a group of connective tissue disorders leading to abnormal bone formation, mainly due to mutations in genes encoding collagen type I (Col I). Osteogenesis is regulated by a number of molecules, including microRNAs (miRNAs), indicating their potential as targets for OI therapy. The goal of this study was to identify and analyze the expression profiles of miRNAs involved in bone extracellular matrix (ECM) regulation in patients diagnosed with OI type I caused by mutations in COL1A1 or COL1A2. Primary skin fibroblast cultures were used for DNA purification and sequence analysis, followed by analysis of miRNA expression. Sequencing analysis revealed mutations of the COL1A1 or COL1A2 genes in all OI patients, including four previously unreported. Amongst the 40 miRNAs analyzed, 9 were identified exclusively in OI cells and 26 in both OI patients and the controls. In the latter case, the expression of six miRNAs (hsa-miR-10b-5p, hsa-miR-19a-3p, hsa-miR-19b-3p, has-miR-204-5p, has-miR-216a-5p, and hsa-miR-449a) increased, while four (hsa-miR-129-5p, hsa-miR-199b-5p, hsa-miR-664a-5p, and hsa-miR-30a-5p) decreased significantly in OI cells in comparison to their expression in the control cells. The identified mutations and miRNA expression profiles shed light on the intricate processes governing bone formation and ECM regulation, paving the way for further research and potential therapeutic advancements in OI and other genetic diseases related to bone abnormality management.

Rhinovirus-induced epithelial RIG-I inflammasome suppresses antiviral immunity and promotes inflammation in asthma and COVID-19

Rhinoviruses and allergens, such as house dust mite are major agents responsible for asthma exacerbations. The influence of pre-existing airway inflammation on the infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is largely unknown. We analyse mechanisms of response to viral infection in experimental in vivo rhinovirus infection in healthy controls and patients with asthma, and in in vitro experiments with house dust mite, rhinovirus and SARS-CoV-2 in human primary airway epithelium. Here, we show that rhinovirus infection in patients with asthma leads to an excessive RIG-I inflammasome activation, which diminishes its accessibility for type I/III interferon responses, leading to their early functional impairment, delayed resolution, prolonged viral clearance and unresolved inflammation in vitro and in vivo. Pre-exposure to house dust mite augments this phenomenon by inflammasome priming and auxiliary inhibition of early type I/III interferon responses. Prior infection with rhinovirus followed by SARS-CoV-2 infection augments RIG-I inflammasome activation and epithelial inflammation. Timely inhibition of the epithelial RIG-I inflammasome may lead to more efficient viral clearance and lower the burden of rhinovirus and SARS-CoV-2 infections.

In vitro human cell-based models to study airway remodeling in asthma

Airway remodeling, as a predominant characteristic of asthma, refers to the structural changes that occurred both in the large and small airways. These pathological changes not only contribute to airway hyperresponsiveness and airway obstruction, but also predict poor outcomes of patients. In vitro models are the alternatives to animal models that facilitate airway remodeling research. Current approaches to mimic airway remodeling in vitro include mono cultures of cell lines and primary cells that are derived from the respiratory tract, and co-culture systems that consist of different cell subpopulations. Moreover, recent advances in microfluid chips and organoids show promise in simulating the complex architecture and functionality of native organs. According, they enable highly physiological-relevant investigations of human diseases in vitro. Here we aim to detail the current human cell-based models regarding their key pros and cons, and to discuss how they may be used to facilitate our understanding of airway remodeling in asthma.

Liquid Application Dosing Alters the Physiology of Air-Liquid Interface Primary Bronchial Epithelial Cultures and In vitro Testing Relevant Endpoints

Differentiated Primary human bronchial epithelial cell (dpHBEC) cultures grown under air-liquid interface (ALI) conditions exhibit key features of the human respiratory tract and are thus critical for respiratory research as well as efficacy and toxicity testing of inhaled substances (e.g., consumer products, industrial chemicals, and pharmaceuticals). Many inhalable substances (e.g., particles, aerosols, hydrophobic substances, reactive substances) have physiochemical properties that challenge their evaluation under ALI conditions in vitro. Evaluation of the effects of these methodologically challenging chemicals (MCCs) in vitro is typically conducted by "liquid application," involving the direct application of a solution containing the test substance to the apical, air-exposed surface of dpHBEC-ALI cultures. We report that the application of liquid to the apical surface of a dpHBEC-ALI co-culture model results in significant reprogramming of the dpHBEC transcriptome and biological pathway activity, alternative regulation of cellular signaling pathways, increased secretion of pro-inflammatory cytokines and growth factors, and decreased epithelial barrier integrity. Given the prevalence of liquid application in the delivery of test substances to ALI systems, understanding its effects provides critical infrastructure for the use of in vitro systems in respiratory research as well as in the safety and efficacy testing of inhalable substances.

BPIFA1 is a secreted biomarker of differentiating human airway epithelium

In vitro culture and differentiation of human-derived airway basal cells under air-liquid interface (ALI) into a pseudostratified mucociliated mucosal barrier has proven to be a powerful preclinical tool to study pathophysiology of respiratory epithelium. As such, identifying differentiation stage-specific biomarkers can help investigators better characterize, standardize, and validate populations of regenerating epithelial cells prior to experimentation. Here, we applied longitudinal transcriptomic analysis and observed that the pattern and the magnitude of OMG, KRT14, STC1, BPIFA1, PLA2G7, TXNIP, S100A7 expression create a unique biosignature that robustly indicates the stage of epithelial cell differentiation. We then validated our findings by quantitative hemi-nested real-time PCR from in vitro cultures sourced from multiple donors. In addition, we demonstrated that at protein-level secretion of BPIFA1 accurately reflects the gene expression profile, with very low quantities present at the time of ALI induction but escalating levels were detectable as the epithelial cells terminally differentiated. Moreover, we observed that increase in BPIFA1 secretion closely correlates with emergence of secretory cells and an anti-inflammatory phenotype as airway epithelial cells undergo mucociliary differentiation under air-liquid interface in vitro.

Role of airway epithelial cell miRNAs in asthma

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

miR-378 associated with proliferation, migration and apoptosis properties in A549 cells and targeted NPNT in COPD

Background

microRNAs contribute to the development and progression of chronic obstructive pulmonary disease (COPD). However, the underlying molecular mechanisms are largely unclear. The goal of this study was to investigate the roles of miR-378 in alveolar epithelial type II cells and identify molecular mechanisms which contribute to the pathogenesis of COPD.

Materials and methods

Human alveolar epithelial (A549) cells were cultured in Dulbecco's Modified Eagle Medium. Cell proliferation was studied by using a cell counting kit-8 (CCK-8) and colony formation assays. Cell apoptosis and cell cycle were analyzed by flow cytometry and wound healing and Transwell were used to analyze the cell migration and. We performed bioinformatics analysis including target gene prediction, gene ontology (GO), Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment and construction of protein-protein interaction (PPI) network. The expression of miR-378 and NPNT from publically available expression microarray of COPD lung tissues was analyzed.

Results

Overexpression of miR-378 significantly increases cell proliferation, migration, and suppress apoptosis. GO analysis demonstrated that the miR-378 involved in transcription, vascular endothelial growth factor receptor signaling pathway, phosphatidylinositol 3-kinase signaling, cell migration, blood coagulation, cell shape, protein stabilization and phosphorylation. Pathway enrichment showed that the 1,629 target genes of miR-378 were associated with mTOR, ErbB, TGF-β, MAPK, and FoxO signaling pathways. Notably, miR-378 directly targets Nephronectin in A549 cells, and miR-378 was upregulated while NPNT was downregulated in COPD lung tissue samples.

Conclusions

These findings suggest that miR-378 can regulate the proliferation, migration, and apoptosis of A549 cells and target NPNT. miR-378 increased in COPD lung tissues while NPNT decreased, and might prove a potential target for novel drug therapy.

MicroRNAs Associated with Chronic Mucus Hypersecretion in COPD Are Involved in Fibroblast-Epithelium Crosstalk

We recently identified microRNAs (miRNAs) associated with chronic mucus hypersecretion (CMH) in chronic obstructive pulmonary disease (COPD), which were expressed in both airway epithelial cells and fibroblasts. We hypothesized that these miRNAs are involved in communication between fibroblasts and epithelium, contributing to airway remodeling and CMH in COPD. Primary bronchial epithelial cells (PBECs) differentiated at the air–liquid interface, and airway fibroblasts (PAFs) from severe COPD patients with CMH were cultured alone or together. RNA was isolated and miRNA expression assessed. miRNAs differentially expressed after co-culturing were studied functionally using overexpression with mimics in mucus-expressing human lung A549 epithelial cells or normal human lung fibroblasts. In PBECs, we observed higher miR-708-5pexpression upon co-culture with fibroblasts, and miR-708-5p expression decreased upon mucociliary differentiation. In PAFs, let-7a-5p, miR-31-5p and miR-146a-5p expression was significantly increased upon co-culture. miR-708-5p overexpression suppressed mucin 5AC (MUC5AC) secretion in A549, while let-7a-5poverexpression suppressed its target gene COL4A1 in lung fibroblasts. Our findings suggest that let-7a-5p, miR-31-5p and miR-146a-5p may be involved in CMH via fibroblasts–epithelium crosstalk, including extracellular matrix gene regulation, while airway epithelial expression of miR-708-5p may be involved directly, regulating mucin production. These findings shed light on miRNA-mediated mechanisms underlying CMH, an important symptom in COPD.

Fine-tuning multiciliated cell differentiation at the post-transcriptional level: contribution of miR-34/449 family members

Cell differentiation is a process that must be precisely regulated for the maintenance of tissue homeostasis. Differentiation towards a multiciliated cell fate is characterized by well-defined stages, where a transcriptional cascade is activated leading to the formation of multiple centrioles and cilia. Centrioles migrate and dock to the apical cell surface and, acting as basal bodies, give rise to multiple motile cilia. The concerted movement of cilia ensures directional fluid flow across epithelia and defects either in their number or structure can lead to disease phenotypes. Micro-RNAs (miRNAs; miRs) are small, non-coding RNA molecules that play an important role in post-transcriptional regulation of gene expression. miR-34b/c and miR-449a/b/c specifically function throughout the differentiation of multiciliated cells, fine-tuning the expression of many different centriole- and cilia-related genes. They strictly regulate the expression levels of genes that are required both for commitment towards the multiciliated cell fate (e.g. Notch) and for the establishment and maintenance of this fate by regulating the expression of transcription factors and structural components of the pathway. Herein we review miR-34 and miR-449 spatiotemporal regulation along with their roles during the different stages of multiciliogenesis.

Transcriptome analysis reveals lung-specific miRNAs associated with impaired mucociliary clearance induced by cigarette smoke in an in vitro human airway tissue model

Exposure to cigarette smoke (CS) is strongly associated with impaired mucociliary clearance (MCC), which has been implicated in the pathogenesis of CS-induced respiratory diseases, such as chronic obstructive pulmonary diseases (COPD). In this study, we aimed to identify microRNAs (miRNAs) that are associated with impaired MCC caused by CS in an in vitro human air-liquid-interface (ALI) airway tissue model. ALI cultures were exposed to CS (diluted with 0.5 L/min, 1.0 L/min, and 4.0 L/min of clean air) from smoking five 3R4F University of Kentucky reference cigarettes under the International Organization for Standardization (ISO) machine smoking regimen, every other day for 1 week (a total of 3 days, 40 min/day). Transcriptome analyses of ALI cultures exposed to the high concentration of CS identified 5090 differentially expressed genes and 551 differentially expressed miRNAs after the third exposure. Genes involved in ciliary function and ciliogenesis were significantly perturbed by repeated CS exposures, leading to changes in cilia beating frequency and ciliary protein expression. In particular, a time-dependent decrease in the expression of miR-449a, a conserved miRNA highly enriched in ciliated airway epithelia and implicated in motile ciliogenesis, was observed in CS-exposed cultures. Similar alterations in miR-449a have been reported in smokers with COPD. Network analysis further indicates that downregulation of miR-449a by CS may derepress cell-cycle proteins, which, in turn, interferes with ciliogenesis. Investigating the effects of CS on transcriptome profile in human ALI cultures may provide not only mechanistic insights, but potential early biomarkers for CS exposure and harm.

ACE2: Evidence of role as entry receptor for SARS-CoV-2 and implications in comorbidities

Pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus 19 disease (COVID-19) which presents a large spectrum of manifestations with fatal outcomes in vulnerable people over 70-years-old and with hypertension, diabetes, obesity, cardiovascular disease, COPD, and smoking status. Knowledge of the entry receptor is key to understand SARS-CoV-2 tropism, transmission and pathogenesis. Early evidence pointed to angiotensin-converting enzyme 2 (ACE2) as SARS-CoV-2 entry receptor. Here, we provide a critical summary of the current knowledge highlighting the limitations and remaining gaps that need to be addressed to fully characterize ACE2 function in SARS-CoV-2 infection and associated pathogenesis. We also discuss ACE2 expression and potential role in the context of comorbidities associated with poor COVID-19 outcomes. Finally, we discuss the potential co-receptors/attachment factors such as neuropilins, heparan sulfate and sialic acids and the putative alternative receptors, such as CD147 and GRP78.

Detargeting Lentiviral-Mediated CFTR Expression in Airway Basal Cells Using miR-106b

Lentiviral-mediated integration of a CFTR transgene cassette into airway basal cells is a strategy being considered for cystic fibrosis (CF) cell-based therapies. However, CFTR expression is highly regulated in differentiated airway cell types and a subset of intermediate basal cells destined to differentiate. Since basal stem cells typically do not express CFTR, suppressing the CFTR expression from the lentiviral vector in airway basal cells may be beneficial for maintaining their proliferative capacity and multipotency. We identified miR-106b as highly expressed in proliferating airway basal cells and extinguished in differentiated columnar cells. Herein, we developed lentiviral vectors with the miR-106b-target sequence (miRT) to both study miR-106b regulation during basal cell differentiation and detarget CFTR expression in basal cells. Given that miR-106b is expressed in the 293T cells used for viral production, obstacles of viral genome integrity and titers were overcome by creating a 293T-B2 cell line that inducibly expresses the RNAi suppressor B2 protein from flock house virus. While miR-106b vectors effectively detargeted reporter gene expression in proliferating basal cells and following differentiation in the air-liquid interface and organoid cultures, the CFTR-miRT vector produced significantly less CFTR-mediated current than the non-miR-targeted CFTR vector following transduction and differentiation of CF basal cells. These findings suggest that miR-106b is expressed in certain airway cell types that contribute to the majority of CFTR anion transport in airway epithelium.

Integrated mRNA and microRNA transcriptome profiling during differentiation of human nasal polyp epithelium reveals an altered ciliogenesis

BACKGROUND

Human adult basal stem/progenitor cells (BSCs) obtained from chronic rhinosinusitis with nasal polyps (CRSwNP) when differentiated in an air-liquid interface (ALI) usually provide a pseudostratified airway epithelium with similar abnormalities than original in vivo phenotype. However, the intrinsic mechanisms regulating this complex process are not well defined and their understanding could offer potential new therapies for CRSwNP (incurable disease).

METHODS

We performed a transcriptome-wide analysis during in vitro mucociliary differentiation of human adult BSCs from CRSwNP, compared to those isolated from control nasal mucosa (control-NM), in order to identify which key mRNA and microRNAs are regulating this complex process in pathological and healthy conditions.

RESULTS

A number of genes, miRs, biological processes, and pathways were identified during mucociliary differentiation of both CRSwNP and control-NM epithelia, and notably, we have demonstrated for the first time that genetic transcriptional program responsible of ciliogenesis and cilia function is significantly impaired in CRSwNP epithelium, presumably produced by an altered expression of microRNAs, particularly of those miRs belonging to mir-34 and mi-449 families.

CONCLUSIONS

This study provides for the first time a novel insight into the molecular basis of sinonasal mucociliary differentiation, demonstrating that transcriptome related to ciliogenesis and cilia function is significantly impaired during differentiation of CRSwNP epithelium due to an altered expression of microRNAs.

Cigarette Smoke Exposure and Inflammatory Signaling Increase the Expression of the SARS-CoV-2 Receptor ACE2 in the Respiratory Tract

The factors mediating fatal SARS-CoV-2 infections are poorly understood. Here, we show that cigarette smoke causes a dose-dependent upregulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 receptor, in rodent and human lungs. Using single-cell sequencing data, we demonstrate that ACE2 is expressed in a subset of secretory cells in the respiratory tract. Chronic smoke exposure triggers the expansion of this cell population and a concomitant increase in ACE2 expression. In contrast, quitting smoking decreases the abundance of these secretory cells and reduces ACE2 levels. Finally, we demonstrate that ACE2 expression is responsive to inflammatory signaling and can be upregulated by viral infections or interferon treatment. Taken together, these results may partially explain why smokers are particularly susceptible to severe SARS-CoV-2 infections. Furthermore, our work identifies ACE2 as an interferon-stimulated gene in lung cells, suggesting that SARS-CoV-2 infections could create positive feedback loops that increase ACE2 levels and facilitate viral dissemination.

Overexpression of miR-455-5p affects retinol (vitamin A) absorption by downregulating STRA6 in a nitrofen-induced CDH with lung hypoplasia rat model

Lung hypoplasia is the main cause of congenital diaphragmatic hernia (CDH)-associated death but pathogenesis remains unclear. MiR-455-5p is involved in lung hypoplasia. We hypothesized that nitrofen causes abnormal miR-455-5p expression during lung development and designed this study to determine the relationship between miR-455-5p, stimulated by retinoic acid 6 (STRA6), and retinol in a nitrofen-induced CDH with lung hypoplasia rat model. Nitrofen or olive oil was administered to Sprague-Dawley rats by gavage on day 9.5 of gestation, and the rats were divided into a nitrofen group and a control group (n = 6). The left lung of fetuses was dissected on day 15.5. The expression of miR-455-5p or STRA6 messenger RNA (mRNA) was determined by quantitative real-time polymerase chain reaction. Average integrated optical density (IOD) of STRA6 protein was determined by immunofluorescence histochemistry. The average retinol level was detected by enzyme-linked immunosorbent assay (n = 6 lungs, respectively). Compared with the control group, the nitrofen group exhibited significantly increased miR-455-5p expression levels (29.450 ± 9.253 vs 5.955 ± 2.330; P = .00045) and significantly decreased STRA6 mRNA levels (0.197 ± 0.097 vs 0.588 ± 0.184; P = .0047). In addition, the average IOD of the STRA6 protein was significantly lower in the nitrofen group (805.643 ± 291.182 vs 1616.391 ± 572.308, P = .015), and the average retinol level was significantly reduced (4.013 ± 0.195 vs 5.317 ± 0.337 µg/L, P = .000). In summary, the overexpression of miR-455-5p affected retinol absorption by downregulating STRA6 in the nitrofen-induced CDH with lung hypoplasia rat model, and this downregulation may be one cause of CDH with lung hypoplasia.

Functional analysis of miRNAs combined with TGF-β1/Smad3 inhibitor in an intrauterine rat adhesion cell model

In this study, we aimed to study the role of miRNAs in intrauterine adhesion (IUA) disease. An IUA cell model was constructed by TGF-β1. Smad3 inhibitor (SIS3) can inhibit the Smad3 signaling pathway and affect the role of TGF-β1; thus, it was used to identify the role of Smad3 and related miRNAs in IUA. Cell number significantly increased in the TGF-β1 group after 72 h and 96 h, respectively, compared with that in the control group (P < 0.05). However, cell proliferation was significantly decreased in the TGF-β1 + SIS3 group (P < 0.0001). Cell apoptosis was increased in the TGF-β1 + SIS3 group compared with that in the TGF-β1 group. Western Blot (WB) analysis suggested that TGF-β1 treatment could effectively increase the expression of α-SMA, COL1, Smad3, and p-Smad3, which could be inhibited by SIS3 treatment. A total of 235 and 530 differentially expressed miRNAs in the TGF-β1 + SIS3 group were significantly up- and downregulated compared with those in the TGF-β1 group, respectively. These differentially expressed miRNAs were enriched in the MAPK and PI3K-AKT pathways. The ten most differentially expressed miRNAs were selected to verify their expressions using quantitative real-time polymerase chain reaction (qPCR). Furthermore, overexpression of rno-miR-3586-3p and rno-miR-455-5p can promote cell proliferation and exacerbate the IUA pathogenic process. However, overexpression of rno-miR-204-3p and rno-miR-3578 can inhibit cell behavior and IUA progression. The above results can provide detailed information for the understanding of IUA molecular mechanisms.

Human airway construct model is suitable for studying transcriptome changes associated with indoor air particulate matter toxicity

In vitro models mimicking the human respiratory system are essential when investigating the toxicological effects of inhaled indoor air particulate matter (PM). We present a pulmonary cell culture model for studying indoor air PM toxicity. We exposed normal human bronchial epithelial cells, grown on semi-permeable cell culture membranes, to four doses of indoor air PM in the air-liquid interface. We analyzed the chemokine interleukin-8 concentration from the cell culture medium, protein concentration from the apical wash, measured tissue electrical resistance, and imaged airway constructs using light and transmission electron microscopy. We sequenced RNA using a targeted RNA toxicology panel for 386 genes associated with toxicological responses. PM was collected from a non-complaint residential environment over 1 week. Sample collection was concomitant with monitoring size-segregated PM counts and determination of microbial levels and diversity. PM exposure was not acutely toxic for the cells, and we observed up-regulation of 34 genes and down-regulation of 17 genes when compared to blank sampler control exposure. The five most up-regulated genes were related to immunotoxicity. Despite indications of incomplete cell differentiation, this model enabled the comparison of a toxicological transcriptome associated with indoor air PM exposure.

Acute Respiratory Barrier Disruption by Ozone Exposure in Mice

Ozone exposure causes irritation, airway hyperreactivity (AHR), inflammation of the airways, and destruction of alveoli (emphysema), the gas exchange area of the lung in human and mice. This review focuses on the acute disruption of the respiratory epithelial barrier in mice. A single high dose ozone exposure (1 ppm for 1 h) causes first a break of the bronchiolar epithelium within 2 h with leak of serum proteins in the broncho-alveolar space, disruption of epithelial tight junctions and cell death, which is followed at 6 h by ROS activation, AHR, myeloid cell recruitment, and remodeling. High ROS levels activate a novel PGAM5 phosphatase dependent cell-death pathway, called oxeiptosis. Bronchiolar cell wall damage and inflammation upon a single ozone exposure are reversible. However, chronic ozone exposure leads to progressive and irreversible loss of alveolar epithelial cells and alveoli with reduced gas exchange space known as emphysema. It is further associated with chronic inflammation and fibrosis of the lung, resembling other environmental pollutants and cigarette smoke in pathogenesis of asthma, and chronic obstructive pulmonary disease (COPD). Here, we review recent data on the mechanisms of ozone induced injury on the different cell types and pathways with a focus on the role of the IL-1 family cytokines and the related IL-33. The relation of chronic ozone exposure induced lung disease with asthma and COPD and the fact that ozone exacerbates asthma and COPD is emphasized.

miR-455-5p Overexpression Reduces Rat Lung Alveolar Type II Cell Proliferation by Downregulating STRA6

miR‐455‐5p and retinoid signaling pathway and its membrane receptor, STRA6, are associated with lung development. Software copredictions indicate that the miRNA upstream of the STRA6 gene is miR‐455‐5p. We hypothesized that miR‐455‐5p participates in rat lung alveolar Type II cell proliferation by targeting STRA6 and designed this study to investigate the effects of miR‐455‐5p overexpression on rat lung alveolar Type II cells. Dual luciferase reporter gene assay was utilized to confirm the relationship between miR‐455‐5p and STRA6. An miR‐455‐5p‐expressing adenoviral vector was constructed and transfected into rat lung alveolar Type II cells. STRA6 protein expression was detected in rat lung alveolar Type II cells by Western blotting at 72 hr posttransfection. Retinol concentration was detected by ELISA at 72 hr posttransfection. The cell proliferation was detected by CCK8 assay at 24, 48, and 72 hr posttransfection. Our results showed that STRA6 is a target gene of miR‐455‐5p. STRA6 protein expression was significantly lower in the miR‐455‐5p‐overexpression group than in the NC group (0.615 ± 0.131 vs. 0.958 ± 0.246, P = 0.029). Similar results were observed for retinol concentration (2.985 ± 0.061 vs. 3.949 ± 0.118, P = 0.000). Rat lung alveolar Type II cell proliferation was lower in the miR‐455‐5p‐overexpression group than in the NC group at 24, 48, and 72 hr posttransfection (24 hr: 0.280 ± 0.184 vs. 1.354 ± 0.169 P = 0.026; 48 hr: 0.881 ± 0.016 vs. 1.992 ± 0.050 P = 0.001; 72 hr: 2.105 ± 0.148 vs. 2.937 ± 0.079 P = 0.016). In summary, miR‐455‐5p is associated with lung development. miR‐455‐5p overexpression downregulates STRA6, leading to reduced retinol concentration and rat lung alveolar Type II cell proliferation. Anat Rec, 302:2062–2069, 2019. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Changes in miRNA Gene Expression during Wound Repair in Differentiated Normal Human Bronchial Epithelium

Purpose

Airway epithelium acts as a protective barrier against the particles from the inhaled air. Damage to the epithelium may result in loss of the barrier function. Epithelial repair in response to injury requires complex mechanisms, such as microRNA, small noncoding molecules, to regulate the processes involved in wound repair. We aimed to establish if the microRNA gene expression profile is altered during the airway epithelial repair in differentiated cells.

Methods

miRNA gene expression profile during the wound closure of differentiated normal human bronchial epithelium (NHBE) from one donor was analysed using quantitative real-time PCR. We have analysed the expression of 754 genes at five time points during a 48-hour period of epithelium repair using TaqMan Low Density Array.

Results

We found out that 233 miRNA genes were expressed in normal human bronchial epithelium. Twenty miRNAs were differentially expressed during the wound repair process, but only one (miR-455-3p) showed significance after FDR adjustment (p = 0.02). Using STEM, we have identified two clusters of several miRNA genes with similar expression profile. Pathway enrichment analysis showed several significant signaling pathways altered during repair, mainly involved in cell cycle regulation, proliferation, migration, adhesion, and transcription regulation.

Conclusions

miRNA expression profile is altered during airway epithelial repair of differentiated cells from one donor in response to mechanical injury in vitro, suggesting their potential role in wound repair.

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

Background

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

Methods

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

Results

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

Conclusion

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

Electronic supplementary material

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

Differential regulation of the transcriptomic and secretomic landscape of sensor and effector functions of human airway epithelial cells

Protein secretion upon TLR, TNFR1, and IFNGR ligation in the human airways is considered to be central for the orchestration of pulmonary inflammatory and immune responses. In this study, we compared the gene expression and protein secretion profiles in response to specific stimulation of all expressed TLRs and in further comparison to TNFR1 and IFNGR in primary human airway epithelial cells. In addition to 22 cytokines, we observed the receptor-induced regulation of 571 genes and 1,012 secreted proteins. Further analysis revealed high similarities between the transcriptional TLR sensor and TNFR1 effector responses. However, secretome to transcriptome comparisons showed a broad receptor stimulation-dependent release of proteins that were not transcriptionally regulated. Many of these proteins are annotated to exosomes with associations to, for example, antigen presentation and wound-healing, or were identified as secretable proteins related to immune responses. Thus, we show a hitherto unrecognized scope of receptor-induced responses in airway epithelium, involving several additional functions for the immune response, exosomal communication and tissue homeostasis.

Neisseria Heparin Binding Antigen is targeted by the human alternative pathway C3-convertase

Neisserial Heparin Binding Antigen (NHBA) is a surface-exposed lipoprotein specific for Neisseria and constitutes one of the three main protein antigens of the Bexsero vaccine. Meningococcal and human proteases, cleave NHBA protein upstream or downstream of a conserved Arg-rich region, respectively. The cleavage results in the release of the C-terminal portion of the protein. The C-terminal fragment originating from the processing of meningococcal proteases, referred to as C2 fragment, exerts a toxic effect on endothelial cells altering the endothelial permeability. In this work, we reported that recombinant C2 fragment has no influence on the integrity of human airway epithelial cell monolayers, consistent with previous findings showing that Neisseria meningitidis traverses the epithelial barrier without disrupting the junctional structures. We showed that epithelial cells constantly secrete proteases responsible for a rapid processing of C2 fragment, generating a new fragment that does not contain the Arg-rich region, a putative docking domain reported to be essential for C2-mediated toxic effect. Moreover, we found that the C3-convertase of the alternative complement pathway is one of the proteases responsible for this processing. Overall, our data provide new insights on the cleavage of NHBA protein during meningococcal infection. NHBA cleavage may occur at different stages of the infection, and it likely has a different role depending on the environment the bacterium is interacting with.

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

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

Association of innate defense proteins BPIFA1 and BPIFB1 with disease severity in COPD

Chronic obstructive pulmonary disease (COPD) is characterized by an abnormal inflammatory response in the lungs caused by the inhalation of noxious particles and gases. The airway epithelium has a protective function against these harmful agents by maintaining a physical barrier and by secreting defensive proteins, such as bactericidal/permeability-increasing fold-containing (BPIF) proteins, BPIFA1 and BPIFB1. However, inconsistent data regarding BPIFA1 expression in smokers and COPD patients have been reported to date. Therefore, we investigated the expression of BPIFA1 and BPIFB1 in a large cohort of never-smokers and smokers with and without COPD, both on the messenger RNA (mRNA) level in lung tissue and on the protein level in airway epithelium. Furthermore, we examined the correlation between BPIFA1 and BPIFB1 levels, goblet cell hyperplasia, and lung function measurements. BPIFA1 and BPIFB1 mRNA expressions were significantly increased in stage III-IV COPD patients compared with stage II COPD patients and subjects without COPD. In addition, protein levels in COPD patients were significantly increased in comparison with subjects without COPD. BPIFA1 and BPIFB1 levels were inversely correlated with measurements of airflow limitation and positively correlated with goblet cell hyperplasia. In addition, by the use of immunofluorescence double staining, we demonstrated the expression of BPIFB1 in goblet cells. In conclusion, we show that BPIFA1 and BPIFB1 levels are elevated in COPD patients and correlate with disease severity.

Genomic comparison of early-passage conditionally reprogrammed breast cancer cells to their corresponding primary tumors

Conditionally reprogrammed cells (CRCs) are epithelial cells that are directly isolated from patients' specimens and propagated in vitro with feeder cells and a Rho kinase inhibitor. A number of these cells have been generated from biopsies of breast cancer patients, including ductal carcinoma in situ and invasive carcinomas. The characterization of their genomic signatures is essential to determine their ability to reflect the natural biology of their tumors of origin. In this study, we performed the genomic characterization of six newly established invasive breast cancer CRC cultures in comparison to the original patients' primary breast tumors (PBT) from which they derived. The CRCs and corresponding PBTs were simultaneously profiled by genome-wide array-CGH, targeted next generation sequencing and global miRNA expression to determine their molecular similarities in the patterns of copy number alterations (CNAs), gene mutations and miRNA expression levels, respectively. The CRCs' epithelial cells content and ploidy levels were also evaluated by flow cytometry. A similar level of CNAs was observed in the pairs of CRCs/PBTs analyzed by array-CGH, with >95% of overlap for the most frequently affected cytobands. Consistently, targeted next generation sequencing analysis showed the retention of specific somatic variants in the CRCs as present in their original PBTs. Global miRNA profiling closely clustered the CRCs with their PBTs (Pearson Correlation, ANOVA paired test, P<0.05), indicating also similarity at the miRNA expression level; the retention of tumor-specific alterations in a subset of miRNAs in the CRCs was further confirmed by qRT-PCR. These data demonstrated that the human breast cancer CRCs of this study maintained at early passages the overall copy number, gene mutations and miRNA expression patterns of their original tumors. The further characterization of these cells by other molecular and cellular phenotypes at late cell passages, are required to further expand their use as a unique and representative ex-vivo tumor model for basic science and translational breast cancer studies.

The cargo protein MAP17 (PDZK1IP1) regulates the immune microenvironment

Inflammation is a complex defensive response activated after various harmful stimuli allowing the clearance of damaged cells and initiating healing and regenerative processes. Chronic, or pathological, inflammation is also one of the causes of neoplastic transformation and cancer development. MAP17 is a cargo protein that transports membrane proteins from the endoplasmic reticulum. Therefore, its overexpression may be linked to an excess of membrane proteins that may be recognized as an unwanted signal, triggering local inflammation. Therefore, we analyzed whether its overexpression is related to an inflammatory phenotype. In this work, we found a correlation between MAP17 expression and inflammatory phenotype in tumors and in other inflammatory diseases such as Crohn's disease, Barrett's esophagus, COPD or psoriasis. MAP17 expression correlated also with the markers of inflammation HLAs, BBS10, HERC2, ADNP and PYCARD. Furthermore, we found that MAP17 expression directly regulates NFAT2 and IL-6 activation, inducing the differentiation of monocytes to dendritic cells and suggesting a causal role of MAP17 in inflammation. Immunohistochemistry confirms local inflammation, mainly CD45⁺ cells, at the site of expression of MAP17, at least in tumors, Crohn's and psoriasis. Therefore, our data indicates that the overexpression of the protein MAP17 plays important role in diseases involving chronic inflammation.

Activation of heat shock response augments fibroblast growth factor-1 expression in wounded lung epithelium

We previously showed that coincident exposure to heat shock (HS; 42°C for 2 h) and TNF-α synergistically induces apoptosis in mouse lung epithelium. We extended this work by analyzing HS effects on human lung epithelial responses to clinically relevant injury. Cotreatment with TNF-α and HS induced little caspase-3 and poly(ADP-ribose) polymerase cleavage in human small airway epithelial cells, A549 cells, and BEAS2B cells. Scratch wound closure rates almost doubled when A549 and BEAS2B cells and air-liquid interface cultures of human bronchial epithelial cells were heat shocked immediately after wounding. Microarray, qRT-PCR, and immunoblotting showed fibroblast growth factor 1 (FGF1) to be synergistically induced by HS and wounding. Enhanced FGF1 expression in HS/wounded A549 was blocked by inhibitors of p38 MAPK (SB203580) or HS factor (HSF)-1 (KNK-437) and in HSF1 knockout BEAS2B cells. PCR demonstrated FGF1 to be expressed from the two most distal promoters in wounded/HS cells. Wound closure in HS A549 and BEAS2B cells was reduced by FGF receptor-1/3 inhibition (SU-5402) or FGF1 depletion. Exogenous FGF1 accelerated A549 wound closure in the absence but not presence of HS. In the presence of exogenous FGF1, HS slowed wound closure, suggesting that it increases FGF1 expression but impairs FGF1-stimulated wound closure. Frozen sections from normal and idiopathic pulmonary fibrosis (IPF) lung were analyzed for FGF1 and HSP70 by immunofluorescence confocal microscopy and qRT-PCR. FGF1 and HSP70 mRNA levels were 7.5- and 5.9-fold higher in IPF than normal lung, and the proteins colocalized to fibroblastic foci in IPF lung. We conclude that HS signaling may have an important impact on gene expression contributing to lung injury, healing, and fibrosis.

miR-125b inhibits goblet cell differentiation in allergic airway inflammation by targeting SPDEF

Asthma is a disease characterized by goblet cell differentiation, mucus hypersecretion, airway inflammation, and airway hyperresponsiveness. miR-125b was downregulated as normal human bronchial epithelial cells differentiation to pseudostratified epithelium. However, its role in asthma remains unknown especially in regulating goblet cell differentiation. miR-125b expression in the sputum of 50 asthmatic children and 50 age- and sex-matched healthy controls were assessed by quantitative RT-PCR (qRT-PCR). Meanwhile, expressions of miR-125b and SAM pointed domain-containing ETS transcription factor (SPDEF) in normal human tracheal epithelial (HTEpC) and A549 cells stimulated with lipopolysaccharide (LPS) for 2h were detected by qRT-PCR and western blot. Furthermore, the predicted miR-125b target was determined in silico and confirmed with dual-luciferase reporter assay. Additionally, intranasal delivery of miR-125b mimic in mice was performed to study its effects on house dust mite-induced allergic airway inflammation mouse models. We found that miR-125b expression was decreased in the sputum of the asthmatic patients especially in eosinophilic asthma. After stimulation with LPS, miR-125b expression was downregulated, accompanied by the upregulation of SPDEF in HTEpC and A549 cells. Moreover, SPDEF is a target of miR-125b, which regulates SPDEF at the posttranscriptional level. Additionally, intranasal delivery of miR-125b decreased SPDEF protein levels, goblet cell differentiation, mucus hypersecretion, and altered relevant gene expressions. Taken together, these results suggest that miR-125b inhibits SPDEF expression modulating goblet cell differentiation and mucus secretion in asthma.

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

Decades of studies have shown evolutionarily conserved molecular networks consisting of transcriptional factors, diffusing growth factors, and signaling pathways that regulate proper lung development. Recently, microRNAs (miRNAs), small, noncoding regulatory RNAs, have been integrated into these networks. Significant advances have been made in characterizing the developmental stage- or cell type-specific miRNAs during lung development by using approaches such as genome-wide profiling and in situ hybridization. Results from gain- or loss-of-function studies revealed pivotal roles of protein components of the miRNA pathway and individual miRNAs in regulating proliferation, apoptosis, differentiation, and morphogenesis during lung development. Aberrant expression or functions of these components have been associated with pulmonary disorders, suggesting their involvement in pathogenesis of these diseases. Moreover, genetically modified mice generated in these studies have become useful models of human lung diseases. Challenges in this field include characterization of collective function and responsible targets of miRNAs specifically expressed during lung development, and translation of these basic findings into clinically relevant information for better understanding of human diseases. The goal of this review is to discuss the recent progress on the understanding of how the miRNA pathway regulates lung development, how dysregulation of miRNA activities contributes to pathogenesis of related pulmonary diseases, and to identify relevant questions and future directions.

Validation of normal human bronchial epithelial cells as a model for influenza A infections in human distal trachea

Primary normal human bronchial/tracheal epithelial (NHBE) cells, derived from the distal-most aspect of the trachea at the bifurcation, have been used for a number of studies in respiratory disease research. Differences between the source tissue and the differentiated primary cells may impact infection studies based on this model. Therefore, we examined how well-differentiated NHBE cells compared with their source tissue, the human distal trachea, as well as the ramifications of these differences on influenza A viral pathogenesis research using this model. We employed a histological analysis including morphological measurements, electron microscopy, multi-label immunofluorescence confocal microscopy, lectin histochemistry, and microarray expression analysis to compare differentiated NHBEs to human distal tracheal epithelium. Pseudostratified epithelial height, cell type variety and distribution varied significantly. Electron microscopy confirmed differences in cellular attachment and paracellular junctions. Influenza receptor lectin histochemistry revealed that α2,3 sialic acids were rarely present on the apical aspect of the differentiated NHBE cells, but were present in low numbers in the distal trachea. We bound fluorochrome bioconjugated virus to respiratory tissue and NHBE cells and infected NHBE cells with human influenza A viruses. Both indicated that the pattern of infection progression in these cells correlated with autopsy studies of fatal cases from the 2009 pandemic.

Vitronectin expression in the airways of subjects with asthma and chronic obstructive pulmonary disease

Vitronectin, a multifunctional glycoprotein, is involved in coagulation, inhibition of the formation of the membrane attack complex (MAC), cell adhesion and migration, wound healing, and tissue remodeling. The primary cellular source of vitronectin is hepatocytes; it is not known whether resident cells of airways produce vitronectin, even though the glycoprotein has been found in exhaled breath condensate and bronchoalveolar lavage from healthy subjects and patients with interstitial lung disease. It is also not known whether vitronectin expression is altered in subjects with asthma and COPD. In this study, bronchial tissue from 7 asthmatic, 10 COPD and 14 control subjects was obtained at autopsy and analyzed by immunohistochemistry to determine the percent area of submucosal glands occupied by vitronectin. In a separate set of experiments, quantitative colocalization analysis was performed on tracheobronchial tissue sections obtained from donor lungs (6 asthmatics, 4 COPD and 7 controls). Vitronectin RNA and protein expressions in bronchial surface epithelium were examined in 12 subjects who undertook diagnostic bronchoscopy. Vitronectin was found in the tracheobronchial epithelium from asthmatic, COPD, and control subjects, although its expression was significantly lower in the asthmatic group. Colocalization analysis of 3D confocal images indicates that vitronectin is expressed in the glandular serous epithelial cells and in respiratory surface epithelial cells other than goblet cells. Expression of the 65-kDa vitronectin isoform was lower in bronchial surface epithelium from the diseased subjects. The cause for the decreased vitronectin expression in asthma is not clear, however, the reduced concentration of vitronectin in the epithelial/submucosal layer of airways may be linked to airway remodeling.

Advances in miRNA-Mediated Mucin Regulation

MicroRNAs (miRNAs) are an important class of small non-coding RNAs that direct post-transcriptional gene regulation by different mechanisms. Mounting evidences from numerous studies in the last decade have unraveled that deregulated miRNAs, and their cognate target expressions are strongly implicated in the carcinogenesis. Recent advances have highlighted miRNA-mediated regulation of mucins that have critical role in inflammation and cancer biology. The aberrant expression and differential glycosylation of mucins cause tumorigenesis, metastasis, chemoresistance and poor outcome of cancer patients, thus recognizing them as attractive therapeutic targets. Though current mucin-based therapies (antibodies, vaccines, immunotherapy, peptide inhibitors) have shown preclinical utility but only a handful promise for clinical transferability. In this context, understanding miRNA-mediated modulation of multiple mucin(s) expression and function gives a new hope for future anti-tumor therapeutics. Herein, we reviewed miRNA biogenesis, mechanism of action, and their role in tumor development. Further, we provide an overview of miRNA-mediated mucin regulation and their application as anticancer therapeutics.

Effect of culture conditions on microRNA expression in primary adult control and COPD lung fibroblasts in vitro

In vitro cell cultures, including lung fibroblasts, have been used to identify microRNAs (miRNAs) associated with chronic obstructive pulmonary disease (COPD) pathogenesis. However, culture conditions may affect miRNA expression. We examined whether miRNA expression in primary adult lung fibroblasts varies with cell density or passage in vitro and whether culture conditions confound the identification of altered miRNA expression in COPD lung fibroblasts. Primary adult control and COPD lung fibroblasts were cultured until passage 3 or 8, after which cells were further cultured for 3 or 7 d (low vs. high density). Then, cells at low density were cultured with serum-free media, and those at high density were cultured with serum-free media in the absence or presence of interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) for 24 h. RNA was extracted to perform miRNA microarray from which 1.25-fold differential expression and 10% false discovery rate were applied to identify "invariant" and "variant" miRNA for the various culture conditions. Of the 2226 miRNAs evaluated, 39.0% for cell density, 40.7% for cell passage, and 29.4% for both conditions were identified as "invariant" miRNAs. Furthermore, 38.1% of the evaluated miRNAs were "invariant" for cell passage with IL-1β and TNF-α. Differentially expressed miRNAs between control and COPD lung fibroblasts were identified with and without IL-1β and TNF-α, and of these, 32 out of the 34 top-ranked miRNAs exceeded the differences due to culture conditions. Thus, culture conditions may affect miRNA expression of adult human lung fibroblasts. Nevertheless, in vitro cultures can be used to assess differential miRNA expression in COPD lung fibroblasts.

Identification of host miRNAs that may limit human rhinovirus replication

AIM: To test whether the replication of human rhinovirus (HRV) is regulated by microRNAs in human bronchial epithelial cells.

METHODS: For the present study, the human cell line BEAS-2B (derived from normal human bronchial epithelial cells) was adopted. DICER knock-down, by siRNA transfection in BEAS-2B cells, was performed in order to inhibit microRNA maturation globally. Alternatively, antisense oligonucleotides (anti-miRs) were transfected to inhibit the activity of specific microRNAs. Cells were infected with HRV-1B. Viral replication was assessed by measuring the genomic viral RNA by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Association between microRNA-induced-silencing-complex and viral RNA was detected by Ago2 co-immunoprecipitation followed by RT-qPCR. Targetscan v.6 was used to predict microRNA target sites on several HRV strains.

RESULTS: Here, we show that microRNAs affect replication of HRV-1B. DICER knock-down significantly reduced the expression of mature microRNAs in a bronchial epithelial cell line (BEAS-2B) and in turn, increased the synthesis of HRV-1B RNA. Additionally, HRV-1B RNA co-immunoprecipitated with argonaute 2 protein, an important effector for microRNA activity suggesting that microRNAs bind to viral RNA during infection. In order to identify specific microRNAs involved in this interaction, we employed bioinformatics analysis, and selected a group of microRNAs that have been reported to be under-expressed in asthmatic bronchial epithelial cells and were predicted to target different strains of rhinoviruses (HRV-1B, -16, -14, -27). Our results suggest that, out of this group of microRNAs, miR-128 and miR-155 contribute to the innate defense against HRV-1B: transfection of specific anti-miRs increased viral replication, as anticipated in-silico.

CONCLUSION: Taken together, our results suggest that pathological changes in microRNA expression, as already reported for asthma or chronic obstructive pulmonary disease have the potential to affect Rhinovirus replication and therefore may play a role in virus-induced exacerbations.

Contemporary avian influenza A virus subtype H1, H6, H7, H10, and H15 hemagglutinin genes encode a mammalian virulence factor similar to the 1918 pandemic virus H1 hemagglutinin

Zoonotic avian influenza virus infections may lead to epidemics or pandemics. The 1918 pandemic influenza virus has an avian influenza virus-like genome, and its H1 hemagglutinin was identified as a key mammalian virulence factor. A chimeric 1918 virus expressing a contemporary avian H1 hemagglutinin, however, displayed murine pathogenicity indistinguishable from that of the 1918 virus. Here, isogenic chimeric avian influenza viruses were constructed on an avian influenza virus backbone, differing only by hemagglutinin subtype expressed. Viruses expressing the avian H1, H6, H7, H10, and H15 subtypes were pathogenic in mice and cytopathic in normal human bronchial epithelial cells, in contrast to H2-, H3-, H5-, H9-, H11-, H13-, H14-, and H16-expressing viruses. Mouse pathogenicity was associated with pulmonary macrophage and neutrophil recruitment. These data suggest that avian influenza virus hemagglutinins H1, H6, H7, H10, and H15 contain inherent mammalian virulence factors and likely share a key virulence property of the 1918 virus. Consequently, zoonotic infections with avian influenza viruses bearing one of these hemagglutinins may cause enhanced disease in mammals.

Influenza viruses from birds can cause outbreaks in humans and may contribute to the development of pandemics. The 1918 pandemic influenza virus has an avian influenza virus-like genome, and its main surface protein, an H1 subtype hemagglutinin, was identified as a key mammalian virulence factor. In a previous study, a 1918 virus expressing an avian H1 gene was as virulent in mice as the reconstructed 1918 virus. Here, a set of avian influenza viruses was constructed, differing only by hemagglutinin subtype. Viruses with the avian H1, H6, H7, H10, and H15 subtypes caused severe disease in mice and damaged human lung cells. Consequently, infections with avian influenza viruses bearing one of these hemagglutinins may cause enhanced disease in mammals, and therefore surveillance for human infections with these subtypes may be important in controlling future outbreaks.

miR455 is linked to hypoxia signaling and is deregulated in preeclampsia

Preeclampsia is a severe pregnancy-related disorder and a leading cause of maternal and fetal mortality worldwide. Early identification of patients with an increased risk for preeclampsia is thus one of the most important goals in obstetrics. Here we identify two related human microRNAs as potential biomarkers to detect at-risk pregnancies. We demonstrate that miR455-3P and miR455-5P are significantly downregulated in placentas from preeclampsia patients, whereas other placenta-specific microRNAs remain unaffected. microRNA target prediction and validation revealed a potential link of miR455-3P to hypoxia signaling. Together with our observation that expression levels of miR455-3P and miR455-5P are upregulated during trophoblast differentiation, our results suggest a model in which miR455-3P represses a hypoxia response that might otherwise prevent cytotrophoblasts from syncytiotrophoblast differentiation. In summary, our work reveals aberrant hypoxia signaling in preeclampsia that can be explained by deregulated expression of miR455. As miR455 has been found in circulating blood, the development of noninvasive prenatal tests enabling early diagnosis of preeclampsia may be possible.

Knockdown of Drosha in human alveolar type II cells alters expression of SP-A in culture: a pilot study

Human surfactant protein A (SP-A) plays an important role in surfactant metabolism and lung innate immunity. SP-A is synthesized and secreted by alveolar type II (ATII) cells, one of the two cell types of the distal lung epithelium (ATII and ATI). We have shown that miRNA interactions with sequence polymorphisms on the SP-A mRNA 3'UTRs mediate differential expression of SP-A1 and SP-A2 gene variants in vitro. In the present study, we describe a physiologically relevant model to study miRNA regulation of SP-A in human ATII. For these studies, we purified and cultured human ATII on an air-liquid interface matrix (A/L) or plastic wells without matrix (P). Gene expression analyses confirmed that cells cultured in A/L maintained the ATII phenotype for over 5 days, whereas P-cultured cells differentiated to ATI. When we transfected ATII with siRNAs to inhibit the expression of Drosha, a critical effector of miRNA maturation, the levels of SP-A mRNA and protein increased in a time dependent manner. We next characterized cultured ATII and ATI by studying expression of 1,066 human miRNAs using miRNA PCR arrays. We detected expression of >300 miRNAs with 24 miRNAs differentially expressed in ATII versus ATI, 12 of which predicted to bind SP-A 3'UTRs, indicating that these may be implicated in SP-A downregulation in ATI. Thus, miRNAs not only affect SP-A expression, but also may contribute to the maintenance of the ATII cell phenotype and/or the trans-differentiation of ATII to ATI cells, and may represent new molecular markers that distinguish ATII and ATI.

miR-34/449 miRNAs are required for motile ciliogenesis by repressing cp110

The mir-34/449 family consists of six homologous miRNAs at three genomic loci. Redundancy of miR-34/449 miRNAs and their dominant expression in multiciliated epithelia suggest a functional significance in ciliogenesis. Here we report that mice deficient for all miR-34/449 miRNAs exhibited postnatal mortality, infertility and strong respiratory dysfunction caused by defective mucociliary clearance. In both mouse and Xenopus, miR-34/449-deficient multiciliated cells (MCCs) exhibited a significant decrease in cilia length and number, due to defective basal body maturation and apical docking. The effect of miR-34/449 on ciliogenesis was mediated, at least in part, by post-transcriptional repression of Cp110, a centriolar protein suppressing cilia assembly. Consistent with this, cp110 knockdown in miR-34/449-deficient MCCs restored ciliogenesis by rescuing basal body maturation and docking. Altogether, our findings elucidate conserved cellular and molecular mechanisms through which miR-34/449 regulate motile ciliogenesis.

Reconstituted human upper airway epithelium as 3-d in vitro model for nasal polyposis

Background

Primary human airway epithelial cells cultured in an air-liquid interface (ALI) develop a well-differentiated epithelium. However, neither characterization of mucociliar differentiation overtime nor the inflammatory function of reconstituted nasal polyp (NP) epithelia have been described.

Objectives

1^st) To develop and characterize the mucociliar differentiation overtime of human epithelial cells of chronic rhinosinusitis with nasal polyps (CRSwNP) in ALI culture system; 2^nd) To corroborate that 3D in vitro model of NP reconstituted epithelium maintains, compared to control nasal mucosa (NM), an inflammatory function.

Methods

Epithelial cells were obtained from 9 NP and 7 control NM, and differentiated in ALI culture for 28 days. Mucociliary differentiation was characterized at different times (0, 7, 14, 21, and 28 days) using ultrastructure analysis by electron microscopy; ΔNp63 (basal stem/progenitor cell), β-tubulin IV (cilia), and MUC5AC (goblet cell) expression by immunocytochemistry; and mucous (MUC5AC, MUC5B) and serous (Lactoferrin) secretion by ELISA. Inflammatory function of ALI cultures (at days 0, 14, and 28) through cytokine (IL-8, IL-1β, IL-6, IL-10, TNF-α, and IL-12p70) and chemokine (RANTES, MIG, MCP-1, IP-10, eotaxin-1, and GM-CSF) production was analysed by CBA (Cytometric Bead Array).

Results

In both NP and control NM ALI cultures, pseudostratified epithelium with ciliated, mucus-secreting, and basal cells were observed by electron microscopy at days 14 and 28. Displaying epithelial cell re-differentation, β-tubulin IV and MUC5AC positive cells increased, while ΔNp63 positive cells decreased overtime. No significant differences were found overtime in MUC5AC, MUC5B, and lactoferrin secretions between both ALI cultures. IL-8 and GM-CSF were significantly increased in NP compared to control NM regenerated epithelia.

Conclusion

Reconstituted epithelia from human NP epithelial cells cultured in ALI system provides a 3D in vitro model that could be useful both for studying the role of epithelium in CRSwNP while developing new therapeutic strategies, including cell therapy, for CRSwNP.

Characterizing and Diminishing Autofluorescence in Formalin-fixed Paraffin-embedded Human Respiratory Tissue

Tissue autofluorescence frequently hampers visualization of immunofluorescent markers in formalin-fixed paraffin-embedded respiratory tissues. We assessed nine treatments reported to have efficacy in reducing autofluorescence in other tissue types. The three most efficacious were Eriochrome black T, Sudan black B and sodium borohydride, as measured using white light laser confocal Λ² (multi-lambda) analysis. We also assessed the impact of steam antigen retrieval and serum application on human tracheal tissue autofluorescence. Functionally fitting this Λ² data to 2-dimensional Gaussian surfaces revealed that steam antigen retrieval and serum application contribute minimally to autofluorescence and that the three treatments are disparately efficacious. Together, these studies provide a set of guidelines for diminishing autofluorescence in formalin-fixed paraffin-embedded human respiratory tissue. Additionally, these characterization techniques are transferable to similar questions in other tissue types, as demonstrated on frozen human liver tissue and paraffin-embedded mouse lung tissue fixed in different fixatives.

Comparative evaluation of miRNA expression between in vitro and in vivo airway epithelium demonstrates widespread differences

Airway epithelial cells cultured at an air-liquid interface bear many hallmarks of in vivo cells and are used extensively to study the biology of the lung epithelium. Because miRNAs regulate many cellular functions, we postulated that miRNA profiling would provide an unbiased assessment of the effects of in vitro culturing. RNA was extracted from primary airway epithelial cells either immediately after cell procurement (in vivo condition) or after air-liquid interface culture was established (in vitro condition). We assessed 742 miRNAs and determined differential expression between in vivo and in vitro conditions. Air-liquid interface culturing of airway epithelial cells caused widespread changes in miRNA expression. A similarly extensive alteration in gene expression was observed in an independent set of publicly available microarray data. We integrated miRNA and gene expression results to identify culture-induced differences in transcriptional programs (including several involved in epithelial injury and repair). Air-liquid interface cultures are useful models for studying airway biology, but the present findings indicate that, despite phenotypic similarities with primary cells, these culture systems profoundly perturb miRNA and gene expression. Studies of lung epithelium based on in vitro culture should therefore be designed and interpreted with an appreciation of the limitations of air-liquid interface culture systems.