Extracellular Vesicle MicroRNA Transfer in Lung Diseases

Exosomal miR-21/Let-7a ratio distinguishes non-small cell lung cancer from benign pulmonary diseases

Aim

To assess the exosomal miR‐21/Let‐7a ratio, a noninvasive method, in distinguishing non‐small cell lung cancer (NSCLC) from benign pulmonary diseases.

Methods

The exosomes were extracted from the peripheral blood serum using serum exosomal extraction kit. miR‐21 and Let‐7a levels were evaluated by quantitative reverse transcription polymerase chain reaction.

Results

We found that miR‐21/Let‐7a ratio of NSCLC patients was significantly higher than that of healthy people, patients with pulmonary inflammation diseases, and benign pulmonary nodules, respectively. Receiver‐operating characteristic analysis revealed that as compared with healthy controls, miR‐21/Let‐7a produced the area under the curve (AUC) at 0.8029 in patients with NSCLC, which helped to distinguish NSCLC from healthy controls with 81.33% sensitivity and 69.57% specificity. In addition, the AUC of miR‐21/Let‐7a in NSCLC patients was 0.8196 in comparison to patients with pulmonary inflammation diseases. Meanwhile, the sensitivity and specificity were 56.00% and 100%, respectively. Furthermore, compared with patients with benign pulmonary nodules, the AUC of miR‐21/Let‐7a in NSCLC patients was 0.7539. The sensitivity and specificity were 56.00% and 82.61%, respectively.

Conclusion

In the present study, our findings revealed that exosomal miR‐21/Let‐7a ratio holds considerable promise as a noninvasive biomarker for the diagnosis of NSCLC from benign pulmonary diseases.

Role of exosomal microRNAs in lung cancer biology and clinical applications

Exosomes, small extracellular vesicles ranging from 30 to 150 nm, are secreted by various cell types, including tumour cells. Recently, microRNAs (miRNAs) were identified to be encapsulated and hence protected from degradation within exosomes. These exosomal miRNAs can be horizontally transferred to target cells, in which they subsequently modulate biological processes. Increasing evidence indicates that exosomal miRNAs play a critical role in modifying the microenvironment of lung cancers, possibly facilitating progression, invasion, angiogenesis, metastasis and drug resistance. In this review, we summarize the novel findings on exosomal miRNA functions during lung cancer initiation and progression. In addition, we highlight their potential role and challenges as biomarkers in lung cancer diagnosis, prognosis and drug resistance and as therapeutic agents.

Mechanisms of Cardiovascular Disorders in Patients With Chronic Kidney Disease: A Process Related to Accelerated Senescence

Cardiovascular diseases (CVDs), especially those involving a systemic inflammatory process such as atherosclerosis, remain the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). CKD is a systemic condition affecting approximately 10% of the general population. The prevalence of CKD has increased over the past decades because of the aging of the population worldwide. Indeed, CVDs in patients with CKD constitute a premature form of CVD observed in the general population. Multiple studies indicate that patients with renal disease undergo accelerated aging, which precipitates the appearance of pathologies, including CVDs, usually associated with advanced age. In this review, we discuss several aspects that characterize CKD-associated CVDs, such as etiopathogenic elements that CKD patients share with the general population, changes in the cellular balance of reactive oxygen species (ROS), and the associated process of cellular senescence. Uremia-associated aging is linked with numerous changes at the cellular and molecular level. These changes are similar to those observed in the normal process of physiologic aging. We also discuss new perspectives in the study of CKD-associated CVDs and epigenetic alterations in intercellular signaling, mediated by microRNAs and/or extracellular vesicles (EVs), which promote vascular damage and subsequent development of CVD. Understanding the processes and factors involved in accelerated senescence and other abnormal intercellular signaling will identify new therapeutic targets and lead to improved methods of diagnosis and monitoring for patients with CKD-associated CVDs.

Aptamer-guided extracellular vesicle theranostics in oncology

In the past decade, the study of exosomes, nanosized vesicles (50-150 nm) released into the extracellular space via the fusion of multivesicular bodies with the plasma membrane, has burgeoned with impressive achievements in theranostics applications. These nanosized vesicles have emerged as key players in homeostasis and in the pathogenesis of diseases owing to the variety of the cargos they can carry, the nature of the molecules packaged inside the vesicles, and the robust interactions between exosomes and target cells or tissues. Accordingly, the development of exosome-based liquid biopsy techniques for early disease detection and for monitoring disease progression marks a new era of precision medicine in the 21st century. Moreover, exosomes possess intrinsic properties - a nanosized structure and unique "homing effects" - that make them outstanding drug delivery vehicles. In addition, targeted exosome-based drug delivery systems can be further optimized using active targeting ligands such as nucleic acid aptamers. Indeed, the aptamers themselves can function as therapeutic and/or diagnostic tools based on their attributes of unique target-binding and non-immunogenicity. This review aims to provide readers with a current picture of the research on exosomes and aptamers and their applications in cancer theranostics, highlighting recent advances in their transition from the bench to the clinic.

A Protocol for Non-biased Identification of RNAs Transferred Between Heterologous Mammalian Cell Types Using RNA Tagging, Cell Sorting, and Sequencing

Intercellular communication is a major hallmark of multicellular organisms and is responsible for coordinating cell and tissue differentiation, immune responses, synaptic transmission, and both paracrine and endocrine signaling, for example. Small molecules, peptides, and proteins have all been studied extensively as mediators of intercellular communication; however, RNAs have also been shown recently to transfer between cells. In mammalian cells, microRNAs, tRNAs, short noncoding RNAs, mRNA fragments, as well as full-length mRNAs have all been shown to transfer between cells either by exosomes or by membrane nanotubes. We have previously described nanotube-mediated cell-cell transfer of specific mRNAs between heterologous mammalian cell types cultured in vitro. Here, we describe a simple method for the unbiased and quantitative identification of the complete range of transferred mRNAs (i.e., the mRNA transferome) in one population of mammalian cells following co-culture with another population. After co-culture, the individual cell populations are sorted by magnetic bead-mediated cell sorting and the transferred RNAs are then identified by downstream analysis methods, such as RNA sequencing. Application of this technique not only allows for determination of the mRNA transferome, but can also reveal changes in the native transcriptome of a cell population after co-culture. This can indicate the effect that co-culture and intercellular transfer of mRNA have upon cell physiology.

Extracellular Vesicles in Non-Small-Cell Lung Cancer: Functional Role and Involvement in Resistance to Targeted Treatment and Immunotherapy

Targeted and immunological therapies have become the gold standard for a large portion of non-small cell lung cancer (NSCLC) patients by improving significantly clinical prognosis. However, resistance mechanisms inevitably develop after a first response, and almost all patients undergo progression. The knowledge of such a resistance mechanism is crucial to improving the efficacy of therapies. So far, monitoring therapy responses through liquid biopsy has been carried out mainly in terms of circulating tumor (ctDNA) analysis. However, other particles of tumor origin, such as extracellular vehicles (EVs) represent an emerging tool for the studying and monitoring of resistance mechanisms. EVs are now considered to be ubiquitous mediators of cell-to-cell communication, allowing cells to exchange biologically active cargoes that vary in response to the microenvironment and include proteins, metabolites, RNA species, and nucleic acids. Novel findings on the biogenesis and fate of these vesicles reveal their fundamental role in cancer progression, with foreseeable and not-far-to-come clinical applications in NSCLC.

Overexpression of MALAT1 Relates to Lung Injury through Sponging miR-425 and Promoting Cell Apoptosis during ARDS

Background

Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury during which severe inflammatory responses induce cell apoptosis, necrosis, and fibrosis. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a multiple function long noncoding RNA that was found overexpressed during acute lung injury. However, the roles of MALAT1 in ARDS patients are still unknown.

Methods

Total RNA was extracted from the plasma, plasma exosome, and peripheral blood mononuclear cells (PBMCs) from 65 ARDS patients and 36 healthy controls. The MALAT1 and six candidate miRNAs levels were detected by qRT-PCR. The interaction between MALAT1 and miR-425 was predicted using a bioinformatics tool and verified by dual luciferase assay. Exosomes from ARDS patients were cultured with A549 and HFL-1 cells to confirm the delivery of miR-425 by exosomes. Cell apoptosis and viability were determined by flow cytometry and MTT assay.

Results

We found MALAT1 was significantly increased in the ARDS patients' plasma and PBMCs. The MALAT1 level in PBMCs was negatively correlated with exosomal miR-425 level. MALAT1 interacted with miR-425 and protected phosphatase and tensin homolog (PTEN) expression in A549 and HFL-1 cells. Exosomes from ARDS patients delivered less miR-425 into A549 and HFL-1 cells and induced cell apoptosis via upregulating PTEN.

Conclusion

This study identified increased MALAT1 and decreased miR-425 in ARDS patients and unveiled their roles during the pathogenesis of ARDS.

Exosomes derived from cancer stem cells of gemcitabine-resistant pancreatic cancer cells enhance drug resistance by delivering miR-210

PURPOSE

Gemcitabine (GEM)-based chemotherapy is the first-line treatment for locally advanced pancreatic cancer. GEM resistance, however, remains a significant clinical challenge. Here, we investigated whether exosomes derived from GEM-resistant pancreatic cancer stem cells (CSCs) mediate cell-cell communication between cells that are sensitive or resistant to GEM and, by doing so, regulate drug resistance.

METHODS

GEM-sensitive BxPC-3-derived Bx_S and PANC-1 pancreatic cancer cells were cultured with exosomes extracted from CSCs isolated from GEM-resistant BxPC-3-derived Bx_R cells (Bx_R-CSC). The effect of exosomes on drug resistance, cell cycle progression, apoptosis and miRNA expression was evaluated in Bx_S and PANC-1 cells. Relevant miRNAs associated with GEM resistance were identified and the role of miR-210 in conferring drug resistance was examined in vitro and in vivo.

RESULTS

Bx_R-CSC-derived exosomes induced GEM resistance, inhibited GEM-induced cell cycle arrest, antagonized GEM-induced apoptosis, and promoted tube formation and cell migration in Bx_S and PANC-1 cells. Elevated miR-210 expression levels were detected in Bx_R-CSCs and Bx_R-CSC-derived exosomes compared to those in Bx_S-CSCs and Bx_S-CSC-derived exosomes. In addition, increased expression levels of miR-210 were observed in Bx_S and PANC-1 cells cultured with Bx_R-CSC-derived exosomes upon exposure to GEM in a dose-dependent manner. Also, a series of biological changes was observed in Bx_S cells after transfection with miR-210 mimics, including activation of the mammalian target of rapamycin (mTOR) signaling pathway, and these changes were similar to those triggered by Bx_R-CSC-derived exosomes.

CONCLUSIONS

Our findings suggest that exosomes derived from GEM-resistant pancreatic cancer stem cells mediate the horizontal transfer of drug-resistant traits to GEM-sensitive pancreatic cancer cells by delivering miR-210.

Upregulation of E-cadherin in bronchoalveolar lavage fluid-derived exosomes in patients with lung cancer

Background

Lung cancer features extremely high rates of morbidity and mortality. Bronchoalveolar lavage fluid (BALF), obtained by bronchoscopy and bronchoalveolar perfusion, can provide information on the cellular components of the lung microenvironment to assist with diagnosis and treatment of lung cancer.

Methods

BALF was performed using a flexible bronchofiberscope. Exosomes were collected by ultracentrifugation. ELISA detected the amount of E‐cadherin. Transmission electron microscopic, ELISA and WB were conducted to identify the existence of the exosomes. Transwell and Wound healing assays were used to detect the ability of migration and invasion.

Results

We identified the existence of exosomes in BALF. Furthermore, we observed larger amounts of E‐cadherin in the BALF obtained from patients with lung cancer than in the control obtained from the healthy side of pneumonia. Exosomes from lung cancer groups promoted the migration and invasion of A549 cancer cells.

Conclusion

The exosomes from lung cancer BALF promoted the migration and invasion of A549 cancer cells by carrying E‐cadherin. E‐cadherin on the surface of exosomes may act through a VE‐cadherin dependent mechanism and induce lung cancer metastasis.

Non-Invasive Approach for Evaluation of Pulmonary Hypertension Using Extracellular Vesicle-Associated Small Non-Coding RNA

Extracellular vesicles are released by numerous cell types of the human body under physiological but also under pathophysiological conditions. They are important for cell–cell communication and carry specific signatures of peptides and RNAs. In this study, we aimed to determine whether extracellular vesicles isolated from patients with pulmonary hypertension show a disease specific signature of small non-coding RNAs and thus have the potential to serve as diagnostic and prognostic biomarkers. Extracellular vesicles were isolated from the serum of 23 patients with chronic thromboembolic pulmonary hypertension (CTEPH) and 23 controls using two individual methods: a column-based method or by precipitation. Extracellular vesicle- associated RNAs were analyzed by next-generation sequencing applying molecular barcoding, and differentially expressed small non-coding RNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR). We identified 18 microRNAs and 21 P-element induced wimpy testis (PIWI)-interacting RNAs (piRNAs) or piRNA clusters that were differentially expressed in CTEPH patients compared with controls. Bioinformatic analysis predicted a contribution of these piRNAs to the progression of cardiac and vascular remodeling. Expression levels of DQ593039 correlated with clinically meaningful parameters such as mean pulmonary arterial pressure, pulmonary vascular resistance, right ventricular systolic pressure, and levels of N-terminal pro-brain natriuretic peptide. Thus, we identified the extracellular vesicle- derived piRNA, DQ593039, as a potential biomarker for pulmonary hypertension and right heart disease.

Effects of chronic PM2.5 exposure on pulmonary epithelia: Transcriptome analysis of mRNA-exosomal miRNA interactions

Epidemiological studies have established the correlations between PM_2.5 and a wide variety of pulmonary diseases. However, their underlying pathogeneses have not been clearly elucidated yet. In the present study, the epithelial-mesenchymal transition (EMT) phenotype with enhanced proliferation and migration activity of human pulmonary epithelial cell line BEAS-2B was observed after exposure to low dose PM_2.5 exposure (50 μg/ml) for 30 passages. Then, epithelial cells derived-exosomal micro-RNA (miRNA) and intracellular total RNA were extracted, and the differentially expressed exosomal miRNAs (DE-Exo-MiRs) as well as differentially expressed protein coding genes (DEGs) were identified by RNA sequencing (RNA-seq) and transcriptome analysis. We found that chronic PM_2.5 exposure stimulated the release of pulmonary epithelium derived exosomes. 45 DE-Exo-MiRs including 32 novelly predicted miRNAs and 843 DEGs between PM_2.5 exposed group and the normal control were detected. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses showed that DEGs were significantly enriched in extracellular matrix organization, focal adhesion and cancer related terms. Besides, the enrichment analyses on 7774 mRNA targets of 27 DE-Exo-MiRs predicted by MiRanda software also revealed the potential regulatory role of exosomal miRNAs in pathways in cancer, Wingless/Integrated (Wnt) signaling pathway, focal adhesion related genes and other multiple pathogenic pathways. Moreover, the interactive exosomal miRNA-mRNA pair networks were constructed using Cytoscape software. Our results provided a novel basis for a better understanding of the mechanisms of chronic PM_2.5 exposure induced pulmonary disorders including pulmonary fibrosis and cancer, in which exosomal miRNAs (Exo-MiRs) potentially functions by dynamically regulating gene expressions.

Serum Exosomal MicroRNAs Predict Acute Respiratory Distress Syndrome Events in Patients with Severe Community-Acquired Pneumonia

BACKGROUND

Severe community-acquired pneumonia (SCAP) requiring intensive care unit (ICU) treatment commonly causes acute respiratory distress syndrome (ARDS) with high mortality. This study was aimed at evaluating whether microRNAs (miRNAs) in circulating exosomes have the predictive values for patients at risk of developing ARDS due to SCAP.

METHODS

ARDS/ALI-relevant miRNAs were obtained by literature search. Exosomes in serum were isolated by ultracentrifugation method and identified by Transmission Electron Microscopy. Then the miR profiling in the exosomes using real-time PCR was analyzed in SCAP patients with or without ARDS. Moreover, multivariate Cox proportional regression analysis was performed to estimate the odds ratio of miRNA for the occurrence of ARDS and prognosis. The receiver operating characteristics (ROC) curves were calculated to discriminate ARDS cases. Finally, the Kaplan-Meier curve using log-rank method was performed to test the equality for survival distributions with different miRNA classifiers.

RESULTS

A total of 53 SCAP patients were finally recruited. Ten miRNAs were picked out. Further, a subset of exosomal miRNAs, including the miR-146a, miR-27a, miR-126, and miR-155 in ARDS group exhibited significantly elevated levels than those in non-ARDS group. The combined expression of miR-126, miR-27a, miR-146a, and miR-155 predicted ARDS with an area under the curve of 0.909 (95 % CI 0.815 -1). Only miR-126 was selected to have potential to predict the 28-day mortality (OR=1.002, P=0.024) with its median value classifier.

CONCLUSIONS

The altered levels of circulating exosomal microRNAs may be useful biologic confirmation of ARDS in patients with SCAP.

miR-425 reduction causes aberrant proliferation and collagen synthesis through modulating TGF-β/Smad signaling in acute respiratory distress syndrome

Background: Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury which may trigger persistent fibrosis. Exosomes are small extracellular vesicles that reflecthost cell conditions and contain functional molecules including miRNAs. Methods: In this study, we isolated plasma exosomes from 53 ARDS patients and 53 controls. Six candidate miRNAs levels were determined by qRT-PCR. The H3K27me3 level on the promoter region of Smad2 was detected by ChIP assay followed by qPCR. Dual luciferase assay and immunoblotting were employed to verify the interaction between miRNA and target genes. The cells proliferation was determined by MTT dependent cell viability assay. Results: miR-425 was reduced in the ARDS patient exosomes. Cytokine treatment also reduced the miR-425 level in A549 and HFL-1 cells. miR-425 inhibition induced Smad2 overexpression by increasing KDM6A level and demethylated H3K27me3 in the Smad2 promoter region. miR-425 reduction induced collagen expression after TGF-β1 treatment and promoted fibroblast proliferation. Conclusion: We identified miR-425 reduction in the exosomes from ARDS patients' peripheral blood, which has the potential to be used as a biomarker for ARDS diagnosis. We demonstrated that miR-425 reduction in lung fibroblasts contributes to the fibrosis through upregulating KDM6A and then activates the TGF-β signaling pathway. This sheds light on the mechanism of lung fibrosis during ARDS.

Function of Adipose-Derived Mesenchymal Stem Cells in Monocrotaline-Induced Pulmonary Arterial Hypertension through miR-191 via Regulation of BMPR2

Pulmonary arterial hypertension (PAH) is a serious condition. However, prevailing therapeutic strategies are not effective enough to treat PAH. Therefore, finding an effective therapy is clearly warranted. Adipose-derived mesenchymal stem cells (ASCs) and ASCs-derived exosomes (ASCs-Exos) exert protective effects in PAH, but the underlying mechanism remains unclear. Using a coculture of ASCs and monocrotaline pyrrole (MCTP)-treated human pulmonary artery endothelial cells (HPAECs), we demonstrated that ASCs increased cell proliferation in MCTP-treated HPAECs. Results showed that ASCs-Exos improved proliferation of both control HPAECs and MCTP-treated HPAECs. In addition, by transfecting ASCs with antagomir we observed that low exosomal miR-191 expression inhibited HPAECs proliferation whereas the agomir improved. Similar results were observed in vivo using a monocrotaline (MCT)-induced PAH rat model following ASCs transplantation. And ASCs transplantation attenuated MCT-induced PAH albeit less than the antagomir treated group. Finally, we found that miR-191 repressed the expression of bone morphogenetic protein receptor 2 (BMPR2) in HPAECs and PAH rats. Thus, we conjectured that miR-191, in ASCs and ASCs-Exos, plays an important role in PAH via regulation of BMPR2. These findings are expected to contribute to promising therapeutic strategies for treating PAH in the future.

Concise Review: Therapeutic Potential of the Mesenchymal Stem Cell Derived Secretome and Extracellular Vesicles for Radiation-Induced Lung Injury: Progress and Hypotheses

Radiation-induced lung injury (RILI) is a common complication in radiotherapy of thoracic tumors and limits the therapeutic dose of radiation that can be given to effectively control tumors. RILI develops through a complex pathological process, resulting in induction and activation of various cytokines, infiltration by inflammatory cells, cytokine-induced activation of fibroblasts, and subsequent tissue remodeling by activated fibroblasts, ultimately leading to impaired lung function and respiratory failure. Increasing evidence shows that mesenchymal stem cells (MSCs) may play a main role in modulating inflammation and immune responses, promoting survival and repair of damaged resident cells and enhancing regeneration of damaged tissue through soluble paracrine factors and therapeutic extracellular vesicles. Therefore, the use of the MSC-derived secretome and exosomes holds promising potential for RILI therapy. Here, we review recent progress on the potential mechanisms of MSC therapy for RILI, with an emphasis on soluble paracrine factors of MSCs. Hypotheses on how MSC derived exosomes or MSC-released exosomal miRNAs could attenuate RILI are also proposed. Problems and translational challenges of the therapies based on the MSC-derived secretome and exosomes are further summarized and underline the need for caution on rapid clinical translation. Stem Cells Translational Medicine 2019;8:344-354.

Distinct plasma gradients of microRNA-204 in the pulmonary circulation of patients suffering from WHO Groups I and II pulmonary hypertension

Pulmonary hypertension (PH), a heterogeneous vascular disease, consists of subtypes with overlapping clinical phenotypes. MicroRNAs, small non-coding RNAs that negatively regulate gene expression, have emerged as regulators of PH pathogenesis. The muscle-specific micro RNA (miR)-204 is known to be depleted in diseased pulmonary artery smooth muscle cells (PASMCs), furthering proliferation and promoting PH. Alterations of circulating plasma miR-204 across the trans-pulmonary vascular bed might provide mechanistic insights into the observed intracellular depletion and may help distinguish PH subtypes. MiR-204 levels were quantified at sequential pulmonary vasculature sites in 91 patients with World Health Organization (WHO) Group I pulmonary arterial hypertension (PAH) (n = 47), Group II PH (n = 22), or no PH (n = 22). Blood from the right atrium/superior vena cava, pulmonary artery, and pulmonary capillary wedge was collected. Peripheral blood mononuclear cells (PBMCs) were isolated (n = 5/group). Excretion of miR-204 by PAH-PASMCs was also quantified in vitro. In Group I patients only, miR-204 concentration increased sequentially along the pulmonary vasculature (log fold-change slope = 0.22 [95% CI = 0.06–0.37], P = 0.008). PBMCs revealed insignificant miR-204 variations among PH groups (P = 0.12). Cultured PAH-PAMSCs displayed a decrease of intracellular miR-204 (P = 0.0004), and a converse increase of extracellular miR-204 (P = 0.0018) versus control. The stepwise elevation of circulating miR-204 across the pulmonary vasculature in Group I, but not Group II, PH indicates differences in muscle-specific pathobiology between subtypes. Considering the known importance of miR-204 in PH, these findings may suggest pathologic excretion of miR-204 in Group I PAH by PASMCs, thereby accounting for decreased intracellular miR-204 concentration.

Mesenchymal stromal cells-derived exosomes alleviate ischemia/reperfusion injury in mouse lung by transporting anti-apoptotic miR-21-5p

MiR-21-5p is an anti-apoptotic miRNA known to mediate the protective effect of mesenchymal stromal cell-secreted exosomes (MSC-Exo) against oxidative stress-induced cell death. In the present research we employed murine lung ischemia/reperfusion (I/R) model and in vitro hypoxia/reoxygenation (H/R) model using primary murine pulmonary endothelial cells to investigate whether MSC-Exo could alleviate lung IRI by transporting miR-21-5p. Our data suggested that intratracheal administration of MSC-Exo or miR-21-5p agomir significantly reduced lung edema and dysfunction, M1 polarization of alveolar macrophages as well as secretion of HMGB1, IL-8, IL-1β, IL-6, IL-17 and TNF-α. Pre-challenge of MSCs by H/R significant increased miR-21-5p expression level in exosomes they secreted and the anti-IRI effect of these MSC-Exo, while pre-treatment of MSCs with miR-21-5p antagomir showed opposite effect. We further demonstrated that MSC-Exo ameliorated IRI in vivo or H/R induced apoptosis in vitro by inhibiting both intrinsic and extrinsic apoptosis pathway via miR-21-5p targeting PTEN and PDCD4, while artificial overexpressing PTEN or PDCD4 significantly attenuated the anti-apoptotic effect of MSC-Exo in vitro. Treatment with miR-21-5p agomir mimicked the IRI-reducing and anti-apoptotic effect of MSC-Exo. Our data suggested that MSC-Exo alleviate IRI in lung in an exosomal miR-21-5p-dependent manner. Treatment with MSC-Exo or miR-21-5p agomir might ameliorate IRI in lung.

miR-146b overexpression ameliorates lipopolysaccharide-induced acute lung injury in vivo and in vitro

Acute respiratory distress syndrome (ARDS) is a type of acute lung injury (ALI), which causes high morbidity and mortality. So far, effective clinical treatment of ARDS is still limited. Recently, miR-146b has been reported to play a key role in inflammation. In the present study, we evaluated the functional role of miR-146b in ARDS using the murine model of lipopolysaccharide (LPS)-induced ALI. The miR-146b expression could be induced by LPS stimulation, and miR-146b overexpression was required in the maintenance of body weight and survival of ALI mice; after miR-146b overexpression, LPS-induced lung injury, pulmonary inflammation, total cell and neutrophil counts, proinflammatory cytokines, and chemokines in bronchial alveolar lavage (BAL) fluid were significantly reduced. The promotive effect of LPS on lung permeability through increasing total protein, albumin and IgM in BAL fluid could be partially reversed by miR-146b overexpression. Moreover, in murine alveolar macrophages, miR-146b overexpression reduced LPS-induced TNF-α and interleukin (IL)-1β releasing. Taken together, we demonstrated that miR-146b overexpression could effectively improve the LPS-induced ALI; miR-146b is a promising target in ARDS treatment.

Extracellular Vesicle-Shuttling MicroRNAs Regulate the Development of Inflammatory Lung Responses

MicroRNAs are small single-stranded, non-coding RNAs which have a known role in post-transcriptional regulation of gene expression. Recent studies have reported that extracellular vesicles are capable of specific delivery of miRNAs to a target cell or tissue from a host cell. MiRNAs are generated by host cells, selectively packaged into EVs, and then delivered to nearby target cells with full functionality. After delivery to the target cells, these EV-packaged miRNAs regulate the translation of their target genes. Thus, EV transported miRNAs have become a newly understood method for intercellular communication. In this review, we summarize the novel findings of EV-miRNA transfer in acute lung injury, chronic obstructive pulmonary disease, bronchopulmonary dysplasia, asthma, and idiopathic pulmonary fibrosis.