Exosomal microRNA-21 derived from bronchial epithelial cells is involved in aberrant epithelium-fibroblast cross-talk in COPD induced by cigarette smoking

Impact of smoking-induced dysregulated human miRNAs in chronic disease development and their potential use in prognostic and therapeutic purposes

MicroRNAs (miRNAs) are evolutionary conserved small noncoding RNA molecules with a significant ability to regulate gene expression at the posttranscriptional level either through translation repression or messenger RNA degradation. miRNAs are differentially expressed in various pathophysiological conditions, affecting the course of the disease by modulating several critical target genes. As the persistence of irreversible molecular changes caused by cigarette smoking is central to the pathogenesis of various chronic diseases, several studies have shown its direct correlation with the dysregulation of different miRNAs, affecting numerous essential biological processes. This review provides an insight into the current status of smoking-induced miRNAs dysregulation in chronic diseases such as COPD, atherosclerosis, pulmonary hypertension, and different cancers and explores the diagnostic/prognostic potential of miRNA-based biomarkers and their efficacy as therapeutic targets.

Extracellular vesicles in respiratory disease

Extracellular vesicles (EVs) are membranous nanoparticles secreted by nearly all cell types and play a critical role in cell-to-cell crosstalk. EVs can be categorized based on their size, surface markers, or the cell type from which they originate. EVs carry "cargo," including but not limited to, RNA, DNA, proteins, and small signaling molecules. To date, many methods have been developed to isolate EVs from biological fluids, such as blood plasma, urine, bronchoalveolar lavage fluid, and urine. Once isolated, EVs can be characterized by dynamic light scattering, nanotracking analysis, nanoscale flow cytometry, and transmission electron microscopy. Given the ability of EVs to transport cargo between cells, research has recently focused on understanding their role in various human diseases. As understanding of their significance to disease processes grows, insight into the mechanisms behind the physiological role of their cargo in target cells can facilitate the development of a new type of biomarker and therapeutic target for diseases in future. In addition, their ability to deliver their cargo selectively to target cells within the human body means that they could serve as therapeutic agents or methods of drug delivery. In this review, we will first introduce EVs and the cargo they carry, outline current methods for EV isolation and characterization, and discuss their potential use as biomarkers and therapeutic agents in the near future.

Epithelial‑derived exosomes promote M2 macrophage polarization via Notch2/SOCS1 during mechanical ventilation

Alveolar macrophages (AMs) play an essential role in ventilator-induced lung injury (VILI). Exosomes and their cargo, including microRNAs (miRNAs/miRs) serve as regulators of the intercellular communications between macrophages and epithelial cells (ECs), and are involved in maintaining homeostasis in lung tissue. The present study found that exosomes released by ECs subjected to cyclic stretching promoted M2 macrophage polarization. It was demonstrated that miR-21a-5p, upregulated in epithelial-derived exosomes, increased the percentage of M2 macrophages by suppressing the expression of Notch2 and the suppressor of cytokine signaling 1 (SOCS1). The overexpression of Notch2 decreased the percentage of M2 macrophages. However, these effects were reversed by the downregulation of SOCS1. The percentage of M2 macrophages was increased in both short-term high- and low-tidal-volume mechanical ventilation, and the administration of exosomes-derived from cyclically stretched ECs had the same function. However, the administration of miR-21a-5p antagomir decreased M2 macrophage activation induced by cyclically stretched ECs or ventilation. Thus, the present study demonstrates that the intercellular transferring of exosomes from ECs to AMs promotes M2 macrophage polarization. Exosomes may prove to be a novel treatment for VILI.

Human epididymis protein 4 aggravates airway inflammation and remodeling in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is a progressive disease characterized by chronic inflammation and airway remodeling. Human epididymis protein 4 (HE4) plays a critical role in various inflammatory or fibrotic diseases. However, the role of HE4 in COPD remains unidentified.

Methods

HE4 expression was determined in the lung tissues from COPD patients and cigarette smoke (CS)-exposed mice using immunohistochemical staining, qPCR, or western blot. The plasma level of HE4 was detected by ELISA. The regulations of HE4 in the expressions of CS extract (CSE)-induced inflammatory cytokines in human bronchial epithelial cells (HBE) were investigated through knockdown or overexpression of HE4. The role of secretory HE4 (sHE4) in the differentiation and proliferation in human pulmonary fibroblast cells (HPF) was explored via qPCR, western blot, CCK8 assay or 5-ethynyl-2′-deoxyuridine (EdU) staining. The probe of related mechanism in CSE-induced HE4 increase in HBE was conducted by administrating N-acetylcysteine (NAC).

Results

HE4 was up-regulated in both the lung tissue and plasma of COPD patients relative to controls, and the plasma HE4 was negatively associated with lung function in COPD patients. The same enhanced HE4 expression was verified in CS-exposed mice and CSE-induced HBE, but CSE failed to increase HE4 expression in HPF. In vitro experiments showed that reducing HE4 expression in HBE alleviated CSE-induced IL-6 release while overexpressing HE4 facilitated IL-6 expression, mechanistically through affecting phosphorylation of NFκB-p65, whereas intervening HE4 expression had no distinctive influence on IL-8 secretion. Furthermore, we confirmed that sHE4 promoted fibroblast-myofibroblast transition, as indicated by promoting the expression of fibronectin, collagen I and α-SMA via phosphorylation of Smad2. EdU staining and CCK-8 assay demonstrated the pro-proliferative role of sHE4 in HPF, which was further confirmed by enhanced expression of survivin and PCNA. Pretreatment of NAC in CSE or H₂O₂-induced HBE mitigated HE4 expression.

Conclusions

Our study indicates that HE4 may participate in airway inflammation and remodeling of COPD. Cigarette smoke enhances HE4 expression and secretion in bronchial epithelium mediated by oxidative stress. Increased HE4 promotes IL-6 release in HBE via phosphorylation of NFκB-p65, and sHE4 promotes fibroblastic differentiation and proliferation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02040-7.

An Emerging Frontier in Intercellular Communication: Extracellular Vesicles in Regeneration

Regeneration requires cellular proliferation, differentiation, and other processes that are regulated by secreted cues originating from cells in the local environment. Recent studies suggest that signaling by extracellular vesicles (EVs), another mode of paracrine communication, may also play a significant role in coordinating cellular behaviors during regeneration. EVs are nanoparticles composed of a lipid bilayer enclosing proteins, nucleic acids, lipids, and other metabolites, and are secreted by most cell types. Upon EV uptake by target cells, EV cargo can influence diverse cellular behaviors during regeneration, including cell survival, immune responses, extracellular matrix remodeling, proliferation, migration, and differentiation. In this review, we briefly introduce the history of EV research and EV biogenesis. Then, we review current understanding of how EVs regulate cellular behaviors during regeneration derived from numerous studies of stem cell-derived EVs in mammalian injury models. Finally, we discuss the potential of other established and emerging research organisms to expand our mechanistic knowledge of basic EV biology, how injury modulates EV biogenesis, cellular sources of EVs in vivo, and the roles of EVs in organisms with greater regenerative capacity.

The Emerging Role of Extracellular Vesicles Detected in Different Biological Fluids in COPD

The pathogenesis of chronic obstructive pulmonary disease (COPD) is characterized by complex cellular and molecular mechanisms, not fully elucidated so far. It involves inflammatory cells (monocytes/macrophages, neutrophils, lymphocytes), cytokines, chemokines and, probably, new players yet to be clearly identified and described. Chronic local and systemic inflammation, lung aging and cellular senescence are key pathological events in COPD development and progression over time. Extracellular vesicles (EVs), released by virtually all cells both as microvesicles and exosomes into different biological fluids, are involved in intercellular communication and, therefore, represent intriguing players in pathobiological mechanisms (including those characterizing aging and chronic diseases); moreover, the role of EVs as biomarkers in different diseases, including COPD, is rapidly gaining recognition. In this review, after recalling the essential steps of COPD pathogenesis, we summarize the current evidence on the roles of EVs collected in different biological mediums as biomarkers in COPD and as potential players in the specific mechanisms leading to disease development. We will also briefly review the data on EV as potential therapeutic targets and potential therapeutic agents.

Diagnosis of Chronic Obstructive Pulmonary Disease and Regulatory Mechanism of miR-149-3p on Alveolar Inflammatory Factors and Expression of Surfactant Proteins A (SP-A) and D (SP-D) on Lung Surface Mediated by Wnt Pathway

Objective

To study the mechanism of chronic obstructive pulmonary disease (COPD) in diagnosing alveolar factors and analyze the effect of miR-149-3p on alveolar inflammatory factors and the expression of surfactant protein D (SP-D) and SP-A on the lung surface mediated by Wnt pathway.

Methods

Patients with stable COPD were taken as the research subjects, and healthy volunteers as the control group. Cardiac color Doppler ultrasound was adopted to measure the ventricular structure of patients. The ultrasound simulation method was introduced in the ultrasound imaging. The ultrasound image was processed based on the intelligent ultrasound simulation algorithm. The changes in the structure of the left and right ventricles were analyzed and compared in the two groups. The expression changes of miR-149-3p, Wnt1, β-catenin, RhoA, and Wnt5a in lung tissues of mice in three groups were detected, as well as the content of tumor necrosis factor- (TNF-) α, IL-1β, interleukin (IL-6), nuclear factor kB (NF-kB), and other inflammatory factors in bronchoalveolar tissues of mice in three groups.

Results

The position where the attenuation ratio was less than 0.92 in the experiment under the ultrasonic simulation algorithm had a gray value of 50. Compared with the control group, the right ventricular mass index of patients with stable COPD was statistically considerable (P < 0.05). In patients with stable COPD, the overall right ventricular longitudinal strain, right ventricular diastolic longitudinal strain rate (RV DLSR), right ventricular diastolic circumferential strain rate, and right ventricular longitudinal displacement were significantly impaired (P < 0.05). The content of miR-149-3p in the lung tissue of the model group was dramatically inferior to that of the control group and the interference group (P < 0.05). The contents of Wnt1, β-catenin, RhoA, and Wnt5a in the lung tissue of the model group were dramatically superior to those of the control group (P < 0.05). In addition, the expressions of TNF-α, IL-1β, IL-6, and NF-kB in the alveolar lavage fluid of the model group were statistically different from those of control group (P < 0.05). The expression levels of SP-D and surfactant protein A (SP-A) in the COPD group were also statistically different from those of control group (P < 0.05).

Conclusion

miR-149-3p regulated the expression of Wnt1, β-catenin, RhoA, and Wnt5a, which also affected the signal transmission of the Wnt pathway, causing changes in the expression of alveolar inflammatory factors. Eventually, it affected the development of COPD.

Extracellular vesicles and chronic obstructive pulmonary disease (COPD): a systematic review

Background

Chronic Obstructive Pulmonary Disease (COPD) is a common inflammatory disease of the airways characterized by irreversible airflow limitation, ranking the third highest cause of death worldwide. Extracellular vesicles (EVs) are important intercellular communication mediators released by cells into their extracellular environment with the capacity to transfer biological signals. EVs involved in COPD hold great potential to understand disease pathogenesis and identify important biomarkers. This systematic review aims to examine all available research on EVs in the pathogenesis and diagnosis of COPD to identify existing knowledge and support further research within the field.

Methods

Publications were searched using PubMed and EMBASE with the search terms (Exosomes or extracellular vesicles or microvesicles or microparticles or ectosomes) AND (chronic obstructive pulmonary disease or COPD or emphysema or bronchitis).

Results

Initial search yielded 512 papers of which 142 were manually selected for review and 43 were eligible for analyses. The studies were divided into groups according to the role of EVs in pathogenesis, EV origin and cargo, their role in COPD exacerbations and their diagnostic utility. EVs were found to be involved in the mechanism of pathogenesis of COPD, derived from various cell types, as well as containing modified levels of miRNAs. EVs also varied according to the pathophysiological status of disease, therefore presenting a possible method for COPD diagnosis and progress monitoring.

Conclusion

The current findings show the limited but good quality research looking at the role of EVs in COPD, demonstrating the need for more studies to better define and provide further insight into the functional characteristics of EV in COPD pathogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01984-0.

Emerging role of exosomes in the pathology of chronic obstructive pulmonary diseases; destructive and therapeutic properties

Chronic obstructive pulmonary disease (COPD) is known as the third leading cause of human death globally. Enhanced chronic inflammation and pathological remodeling are the main consequences of COPD, leading to decreased life span. Histological and molecular investigations revealed that prominent immune cell infiltration and release of several cytokines contribute to progressive chronic remodeling. Recent investigations have revealed that exosomes belonging to extracellular vesicles are involved in the pathogenesis of COPD. It has been elucidated that exosomes secreted from immune cells are eligible to carry numerous pro-inflammatory factors exacerbating the pathological conditions. Here, in this review article, we have summarized various and reliable information about the negative role of immune cell-derived exosomes in the remodeling of pulmonary tissue and airways destruction in COPD patients.

RNA sequencing reveals the emerging role of bronchoalveolar lavage fluid exosome lncRNAs in acute lung injury

Background

Bronchoalveolar lavage fluid (BALF) exosomes possess different properties in different diseases, which are mediated through microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), among others. By sequencing the differentially expressed lncRNAs in BALF exosomes, we seek potential targets for the diagnosis and treatment of acute lung injury (ALI).

Methods

Considering that human and rat genes are about 80% similar, ALI was induced using lipopolysaccharide in six male Wistar rats, with six rats as control (all weighing 200 ± 20 g and aged 6-8 weeks). BALF exosomes were obtained 24 h after ALI. The exosomes in BALF were extracted by ultracentrifugation. The differential expression of BALF exosomal lncRNAs in BALF was analyzed by RNA sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the functions of differentially expressed lncRNAs, which were confirmed by reverse transcription-polymerase chain reaction.

Results

Compared with the control group, the ALI group displayed a higher wet/dry ratio, tumor necrosis factor-α levels, and interleukin-6 levels (all P < 0.001). The airway injection of exosomes in rats led to significant infiltration by neutrophils. A total of 2,958 differentially expressed exosomal lncRNAs were identified, including 2,524 upregulated and 434 downregulated ones. Five lncRNAs confirmed the reliability of the sequencing data. The top three GO functions were phagocytic vesicle membrane, regulation of receptor biosynthesis process, and I-SMAD binding. Salmonella infection, Toll-like receptor signaling pathway, and osteoclast differentiation were the most enriched KEGG pathways. The lncRNA-miRNA interaction network of the five confirmed lncRNAs could be predicted using miRDB.

Conclusions

BALF-derived exosomes play an important role in ALI development and help identify potential therapeutic targets related to ALI.

Vitamin D3 alleviates cigarette smoke extract‑mediated epithelial‑mesenchymal transition and fibrogenesis by upregulating CC16 expression in bronchial epithelial cells

Vitamin D3 supplementation has been previously reported to inhibit the occurrence and development of chronic obstructive pulmonary disease (COPD). However, the underlying mechanism remains unclear. Epithelial-mesenchymal transition (EMT) and fibrogenesis have been associated with the development of COPD. The aim of the present study was to investigate the potential effects and mechanism of vitamin D3 in an in vitro model of cigarette smoke (CS)-induced EMT and fibrosis, with specific focus on the role of club cell protein 16 (CC16). CS extract (CSE) at different concentrations (5, 10 and 20%) was used to treat 16-HBE cells to induce EMT and fibrogenesis following which they were treated with vitamin D3. Subsequently, the 20% CSE group was selected for further experiments, where 16-HBE cells were divided into the following five groups: The control group; the CSE group; the low-dose vitamin D3 group (250 nM); the medium-dose vitamin D3 group (500 nM); and the high-dose vitamin D3 group (1,000 nM). Western blot analysis was used to detect the protein expression levels of the EMT-related proteins E-cadherin, N-cadherin, Slug and α-SMA, fibrogenesis-related proteins collagen Ⅳ and fibronectin 1, proteins involved in the TGF-β1/SMAD3 signaling pathway and CC16. Immunofluorescence was used to measure the protein expression levels of E-cadherin, N-cadherin and collagen Ⅳ. Specific CC16 knockdown was performed using short hairpin RNA transfection to investigate the role of CC16. The results of the present study found that vitamin D3 could increase the protein expression level of CC16 to inhibit the activation of the TGF-β1/SMAD3 signaling pathway; thereby reducing the 20% increase in CSE-induced EMT- and fibrogenesis-related protein expression levels. Following CC16 knockdown, the inhibitory effects of vitamin D3 on EMT- and fibrogenesis-related protein expression were partially reversed. To conclude, these results suggest that vitamin D3 can inhibit the protein expression levels of EMT- and fibrogenesis-related proteins induced by CSE, at least partially through the function of CC16. These findings are expected to provide novel theoretical foundations and ideas for the pathogenesis and treatment of COPD.

Suppression of Cutibacterium acnes-Mediated Inflammatory Reactions by Fibroblast Growth Factor 21 in Skin

Cutibacterium acnes (C. acnes) is a common commensal bacterium that is closely associated with the pathogenesis of acne. Fibroblast growth factor 21 (FGF21), as a favorable regulator of glucose and lipid metabolism and insulin sensitivity, was recently shown to exert anti-inflammatory effects. The role and mechanism of FGF21 in the inflammatory reactions induced by C. acnes, however, have not been determined. The present study shows that FGF21 in the dermis inhibits epidermal C. acnes-induced inflammation in a paracrine manner while it functions on the epidermal layer through a receptor complex consisting of FGF receptor 1 (FGFR1) and β-Klotho (KLB). The effects of FGF21 in heat-killed C. acnes-induced HaCaT cells and living C. acnes-injected mouse ears were examined. In the presence of C. acnes, FGF21 largely counteracted the activation of Toll-like receptor 2 (TLR2), the downstream nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPK) signaling pathways induced by C. acnes. FGF21 also significantly reduced the expression of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α. Taken together, these findings indicate that FGF21 suppresses C. acnes-induced inflammation and might be used clinically in the management and treatment of acne.

The Emerging Role of Macrophages in Chronic Obstructive Pulmonary Disease: The Potential Impact of Oxidative Stress and Extracellular Vesicle on Macrophage Polarization and Function

Chronic obstructive pulmonary disease (COPD) is one of the most common airway diseases, and it is considered a major global health problem. Macrophages are the most representative immune cells in the respiratory tract, given their role in surveying airways, removing cellular debris, immune surveillance, and resolving inflammation. Macrophages exert their functions by adopting phenotypical changes based on the stimuli they receive from the surrounding tissue. This plasticity is described as M1/M2 macrophage polarization, which consists of a strictly coordinated process leading to a difference in the expression of surface markers, the production of specific factors, and the execution of biological activities. This review focuses on the role played by macrophages in COPD and their implication in inflammatory and oxidative stress processes. Particular attention is on macrophage polarization, given macrophage plasticity is a key feature in COPD. We also discuss the regulatory influence of extracellular vesicles (EVs) in cell-to-cell communications. EV composition and cargo may influence many COPD-related aspects, including inflammation, tissue remodeling, and macrophage dysfunctions. These findings could be useful for better addressing the role of macrophages in the complex pathogenesis and outcomes of COPD.

Epigenetic Biomarkers Screening of Non-Coding RNA and DNA Methylation Based on Peripheral Blood Monocytes in Smokers

This study aims to use bioinformatics methods to determine the epigenetic changes in microRNA expression and DNA methylation caused by cigarette smoking. The data of mRNA, miRNA expression, and methylation microarray were obtained from the GEO database to filter differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and methylated CpG probes (DMPs) through the limma package. The R clusterProfile package was used for functional annotation and enrichment analysis. The protein-protein interaction (PPI) network was constructed by the String database and visualized in Cytoscape software. Starbase database was employed to predict lncRNA and CirRNA based on the sequence of miRNA, and to establish a regulatory network of ceRNA. By overlapping DEG and DEM, 107 down-miRNA-targeted up-regulated genes and 65 up-miRNA-target down-regulated genes were obtained, which were mainly enriched in autophagy signaling pathways and protein ubiquitination pathways, respectively. In addition, 324 genes with low methylation and high expression and 204 genes with high methylation and low expression were respectively related to the degeneration of the nervous system and the function of the cardiovascular system. Interestingly, 43 genes were up-regulated under the dual regulation of reduced miRNA and hypomethylation, while 14 genes were down-regulated under the dual regulation of increased miRNA and hypermethylation. Ten chemicals have been identified as putative therapeutic agents for pathological conditions caused by smoking. In addition, among these genes, HSPA4, GRB2, PRKCA, and BCL2L1 could play a fundamental role in related diseases caused by smoking and may be used as the biomarkers for precise diagnosis and targets for future therapies of smoking-related diseases.

Extracellular Vesicles as Central Mediators of COPD Pathophysiology

Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous, smoking-related disease of significant global impact. The complex biology of COPD is ultimately driven by a few interrelated processes, including proteolytic tissue remodeling, innate immune inflammation, derangements of the host-pathogen response, aberrant cellular phenotype switching, and cellular senescence, among others. Each of these processes are engendered and perpetuated by cells modulating their environment or each other. Extracellular vesicles (EVs) are powerful effectors that allow cells to perform a diverse array of functions on both adjacent and distant tissues, and their pleiotropic nature is only beginning to be appreciated. As such, EVs are candidates to play major roles in these fundamental mechanisms of disease behind COPD. Furthermore, some such roles for EVs are already established, and EVs are implicated in significant aspects of COPD pathogenesis. Here, we discuss known and potential ways that EVs modulate the environment of their originating cells to contribute to the processes that underlie COPD.

Endothelial Microparticles Derived from Primary Pulmonary Microvascular Endothelial Cells Mediate Lung Inflammation in Chronic Obstructive Pulmonary Disease by Transferring microRNA-126

Background

Extracellular vesicles (EVs) are considered to new types of intercellular communication media, and microRNA is one of the most common transferring components of EVs. This study aimed to explore the potential role of endothelial microparticles (EMPs) derived from primary pulmonary microvascular endothelial cells in regulating lung inflammation of chronic obstructive pulmonary disease (COPD) through transferring microRNA-126 (miR-126).

Methods

EMPs generated from primary pulmonary microvascular endothelial cells were isolated by gradient centrifugation and characterized by transmission electron microscopy, flow cytometry and Western blotting. EMPs were treated to in vitro and in vivo COPD models induced by cigarette smoke extract (CSE). miR-126 mimics or inhibitors were transfected into EMPs by calcium chloride. Pathological changes of lung tissue, mRNA and protein levels of inflammation-related factors were measured to explore the effect of EMPs transferring miR-126 on CSE-induced inflammation.

Results

Both in vitro and in vivo studies demonstrated that mRNA and protein levels of inflammation-related factors were significantly increased in COPD group, while EMPs could dramatically reverse these increases. In vitro, overexpression of miR-126 in EMPs decreased HMGB1 expression and magnified the decreasing effect of EMPs on inflammation-related factors.

Conclusion

The present study reveals that EMPs are capable of alleviating lung inflammation and transferring miR-126 can magnify the anti-inflammatory effect of EMPs, which may provide a novel therapeutic alternative for COPD.

Regulation of lung epithelial cell senescence in smoking-induced COPD/emphysema by microR-125a-5p via Sp1 mediation of SIRT1/HIF-1a

Chronic obstructive pulmonary disease (COPD) affects the health of more than 300 million people worldwide; at present, there is no effective drug to treat COPD. Smoking is the most important risk factor, but the molecular mechanism by which smoking causes the disease is unclear. The senescence of lung epithelial cells is related to development of COPD. Regulation of miRNAs is the main epigenetic mechanism related to aging. β-Galactose staining showed that the lung tissues of smokers have a higher degree of cellular senescence, and the expression of miR-125a-5p is high. This effect is obvious for smokers with COPD/emphysema, and there is a negative correlation between miR-125a-5p levels and values for forced expiratory volume in one second (FEV1)/forced vital capacity (FVC). After Balb/c mice were chronically exposed to various concentrations of cigarette smoke (CS), plethysmography showed that lung function was impaired, lung tissue senescence was increased, and the senescence-associated secretory phenotype (SASP) in bronchoalveolar lavage fluid was increased. For mouse lung epithelial (MLE)-12 cells treated with cigarette smoke extract (CSE), Sp1 and SIRT1 levels were low, HIF-1α acetylation levels were high, and cell senescence and secretion of SASP factors were elevated. Down-regulation of miR-125a-5p or up-regulation of Sp1 reversed these effects. In addition, compared with mice exposed to CS, knockdown of miR-125a-5p reduced lung epithelial cell senescence and COPD/emphysema. Therefore, in smoking-induced COPD, elevated miR-125a-5p participates in the senescence of lung epithelial cells through Sp1/SIRT1/HIF-1α. These findings provide evidence related to the pathogenesis of COPD/emphysema caused by chronic smoking.

Current views in chronic obstructive pulmonary disease pathogenesis and management

Chronic obstructive pulmonary disease (COPD) is a progressive lung dysfunction caused mainly by inhaling toxic particles and cigarette smoking (CS). The continuous exposure to ruinous molecules can lead to abnormal inflammatory responses, permanent damages to the respiratory system, and irreversible pathological changes. Other factors, such as genetics and aging, influence the development of COPD. In the last decade, accumulating evidence suggested that mitochondrial alteration, including mitochondrial DNA damage, increased mitochondrial reactive oxygen species (ROS), abnormal autophagy, and apoptosis, have been implicated in the pathogenesis of COPD. The alteration can also extend to epigenetics, namely DNA methylation, histone modification, and non-coding RNA. This review will discuss the recent progressions in COPD pathology, pathophysiology, and molecular pathways. More focus will be shed on mitochondrial and epigenetic variations related to COPD development and the role of nanomedicine as a potential tool for the prevention and treatment of this disease.

Anti-infection roles of miR-155-5p packaged in exosomes secreted by dendritic cells infected with Toxoplasma gondii

Background

Toxoplasma gondii is a zoonotic intracellular protozoon that is estimated to infect about 30% of the world’s population, resulting in toxoplasmosis in immunocompromised patients and adverse outcomes in cases of primary infection during pregnancy. Exosomes are tubular vesicles secreted by cells, and function in intercellular communication. It has been reported that the exosomes secreted by T. gondii-infected immune cells transmit infection signals to the uninfected cells. However, the mechanism and effect of the exosome transmission are still vague. We therefore investigated the function of the exosomes transmitted from DC2.4 cells infected with the T. gondii RH strain (Tg-DC-Exo) to the uninfected cells, as well as their roles in anti-infection.

Methods

We conducted exosome isolation and identification with ultracentrifugation, transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot (WB) analysis. Exosome uptake by recipient cells was identified by PKH67 assay. The signal transmission and the abundance of miR-155-5p were determined using transwell assay and qRT-PCR. For detection of immune responses, cytokine secretion was evaluated. The T. gondii B1 gene was determined to evaluate tachyzoite proliferation.

Results

We observed that Toxoplasma infection upregulated miR-155-5p expression in DC2.4 cell-secreted exosomes, and those exosomes could be ingested by murine macrophage RAW264.7 cells. Tg-DC-Exo and miR-155-5p stimulated host proinflammatory immune responses including increased production of proinflammatory cytokines IL-6 and TNF-α, and proinflammatory marker-inducible nitric oxide synthase (iNOS). The NF-κB pathway was activated by downregulation of SOCS1, leading to inhibition of T. gondii tachyzoite proliferation in RAW264.7 cells.

Conclusions

Our findings provide a novel mechanism for how infected cells transmit infection signals to the uninfected cells through exosome secretion after T. gondii infection, followed by inflammatory responses and anti-infection reactions, which may help us develop a new strategy for toxoplasmosis prevention, especially in immunocompromised patients.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05003-x.

Circulating exosome level of indigenous fish may be a novel biomarker for the integrated ecotoxicity effect of water environment

The deficiency of effective biomarker for the toxic effects of water pollutants greatly limits the application of biological monitoring. This study aimed to investigate the possibility of circulating exosomes of indigenous fish acting as biomarker for the ecotoxicity effect of water environment. The Helong Reservoir in Guangzhou, China, was chosen as the investigating field, of which the water quality belongs to Class V (2013) (GB 3838-2002, China). The clean drinking water source of the upper reaches of the Liuxihe Reservoir was selected as the control. Indigenous fishes including Oreochromis niloticus (Nile tilapia), Labeo rohita (Rohu), Carassius auratus (Crucian carp) were sampled during the period from July 2020 to April 2021. Circulating exosomes of fish samples were isolated by using ultracentrifugation, characterized with transmission electron microscopy (TEM) and quantified by using bicinchoninic acid (BCA) assay. Oxidative stress, DNA and chromosome damage in liver, kidney, brain, gill and blood of fish samples were measured. The results showed that there were significant differences in superoxide dismutase (SOD) activity, glutathione (GSH) and malondialdehyde (MDA) contents, DNA and chromosome damage in fish samples between the Helong Reservoir and the control. Interestingly, there were also significant differences in circulating exosome levels of fish samples between them. Our data suggested that circulating exosome level of indigenous fish may be a novel biomarker for the ecotoxicity effects of water environment.

The Role of Extracellular Vesicles as a Shared Disease Mechanism Contributing to Multimorbidity in Patients With COPD

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide. Individuals with COPD typically experience a progressive, debilitating decline in lung function as well as systemic manifestations of the disease. Multimorbidity, is common in COPD patients and increases the risk of hospitalisation and mortality. Central to the genesis of multimorbidity in COPD patients is a self-perpetuating, abnormal immune and inflammatory response driven by factors including ageing, pollutant inhalation (including smoking) and infection. As many patients with COPD have multiple concurrent chronic conditions, which require an integrative management approach, there is a need to greater understand the shared disease mechanisms contributing to multimorbidity. The intercellular transfer of extracellular vesicles (EVs) has recently been proposed as an important method of local and distal cell-to-cell communication mediating both homeostatic and pathological conditions. EVs have been identified in many biological fluids and provide a stable capsule for the transfer of cargo including proteins, lipids and nucleic acids. Of these cargo, microRNAs (miRNAs), which are short 17-24 nucleotide non-coding RNA molecules, have been amongst the most extensively studied. There is evidence to support that miRNA are selectively packaged into EVs and can regulate recipient cell gene expression including major pathways involved in inflammation, apoptosis and fibrosis. Furthermore changes in EV cargo including miRNA have been reported in many chronic diseases and in response to risk factors including respiratory infections, noxious stimuli and ageing. In this review, we discuss the potential of EVs and EV-associated miRNA to modulate shared pathological processes in chronic diseases. Further delineating these may lead to the identification of novel biomarkers and therapeutic targets for patients with COPD and multimorbidities.

Bioinformatics analyses of the pathogenesis and new biomarkers of chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is one of the major cause of global death. The purpose of our analysis was to detect a more reliable biomarker and small-molecule drug candidates and to identify the precise mechanisms involved in COPD.

METHODS

Three data sets were downloaded from the Gene Expression Omnibus database and analysed by Gene Expression Omnibus 2R. Functional enrichment analyses were performed by Metascape. We use the STRING data to build a protein-protein interaction network. The targets of differentially expressed microRNA (DE miRNA) were predicted by the miRWalk database. Small-molecule drugs were predicted on connectivity map.

RESULTS

A total of 181 differentially expressed genes and 35 DE miRNAs were confirmed. The protein-protein interaction network including all integrated differentially expressed genes was constructed, and 4 modules were filtrated. The module genes were relative to immune, inflammatory and oxidative stress functions according to a pathway analysis. The top 20 key genes were screened. Among the DE miRNAs found to be regulating key genes, miR-194-3p, MiR-502-5p, MiR-5088-5p, MiR-3127-5p, and miR-23a-5p might be the most significant due to their high number of connecting nodes in COPD. In addition, cephaeline, emetine, gabapentin, and amrinone were found to be potential drugs to treat COPD patients.

CONCLUSION

Our study suggests that miR-194-3p, miR-502-5p, and miR-23a-5p might participate in the nosogenesis of COPD. In addition, 4 potential small-molecule drugs were considered potentially useful for treating COPD patients.

Regulation of airway immunity by epithelial miRNAs

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

Involvement of epithelia-derived exosomes in chronic respiratory diseases

Exosomes are tiny membrane lipid bilayer vesicles (φ40-100 nm) formed by the fusion of multivesicular bodies with plasma membrane, which are released extracellular by exocytosis. As natural nanocarriers, exosomes contain a variety of signal substances of the mother cell: nucleic acids, proteins and lipids, etc., which always play a vital role in the transmission of signal molecules between different cells. Epithelial cells are the first-line defense system against various inhaled allergens causing chronic respiratory diseases (CRD), such as asthma and chronic obstructive pulmonary disease (COPD). It's noted that increasing literature shows the exosomes derived from epithelial cells are involved in the pathogenesis of CRD. Moreover, the correlations between exosome cargo and the disease phenotypes show a high potential of using exosomes as biomarkers of CRD. In this review, we mainly focus on the physiological functions of epithelial-derived exosomes and illustrate the involved mechanism of epithelial-derived exosomes in common CRD.

Exosomal miR-21 from tubular cells contributes to renal fibrosis by activating fibroblasts via targeting PTEN in obstructed kidneys

Rationale: Ureteral obstruction-induced hydronephrosis is associated with renal fibrosis and progressive chronic kidney disease (CKD). Exosome-mediated cell-cell communication has been suggested to be involved in various diseases, including renal fibrosis. However, little is known regarding how exosomes regulate renal fibrosis in obstructed kidneys.

Methods: We first examined the secretion of exosomes in UUO (unilateral ureteral obstruction) mouse kidneys and TGF-β1-stimulated tubular epithelial cells (NRK-52E). Exosomes from NRK-52E cells were subsequently harvested and incubated with fibroblasts (NRK-49F) or injected into UUO mice via the tail vein. We next constructed Rab27a knockout mice to further confirm the role of exosome-mediated epithelial-fibroblast communication relevant to renal fibrosis in UUO mice. High-throughput miRNA sequencing was performed to detect the miRNA profiles of TGFβ1-Exos. The roles of candidate miRNAs, their target genes and relevant pathways were predicted and assessed in vitro and in vivo by setting specific miRNA mimic, miRNA inhibitor, siRNA or miRNA LNA groups.

Results: Increased renal fibrosis was associated with prolonged UUO days, and the secretion of exosomes was markedly increased in UUO kidneys and TGF-β1-stimulated NRK-52E cells. Purified exosomes from TGF-β1-stimulated NRK-52E cells could activate fibroblasts and aggravate renal fibrosis in vitro and in vivo. In addition, the inhibition of exosome secretion by Rab27a knockout or GW4869 treatment abolished fibroblast activation and ameliorated renal fibrosis. Exosomal miR-21 was significantly increased in TGFβ1-Exos compared with Ctrl-Exos, and PTEN is a certain target of miR-21. The promotion or inhibition of epithelial exosomal miR-21 correspondingly accelerated or abolished fibroblast activation in vitro, and renal fibrosis after UUO was alleviated by miR-21-deficient exosomes in vivo through the PTEN/Akt pathway.

Conclusion: Our findings reveal that exosomal miR-21 from tubular epithelial cells may accelerate the development of renal fibrosis by activating fibroblasts via the miR-21/PTEN/Akt pathway in obstructed kidneys.

Racial Health Disparity and COVID-19

Abstract

The infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and resultant coronavirus diseases-19 (COVID-19) disproportionally affects minorities, especially African Americans (AA) compared to the Caucasian population. The AA population is disproportionally affected by COVID-19, in part, because they have high prevalence of underlying conditions such as obesity, diabetes, and hypertension, which are known to exacerbate not only kidney diseases, but also COVID-19. Further, a decreased adherence to COVID-19 guidelines among tobacco smokers could result in increased infection, inflammation, reduced immune response, and lungs damage, leading to more severe form of COVID-19. As a result of high prevalence of underlying conditions that cause kidney diseases in the AA population coupled with tobacco smoking make the AA population vulnerable to severe form of both COVID-19 and kidney diseases. In this review, we describe how tobacco smoking interact with SARS-CoV-2 and exacerbates SARS-CoV-2-induced kidney diseases including renal failure, especially in the AA population. We also explore the role of extracellular vesicles (EVs) in COVID-19 patients who smoke tobacco. EVs, which play important role in tobacco-mediated pathogenesis in infectious diseases, have also shown to be important in COVID-19 pathogenesis and organ injuries including kidney. Further, we explore the potential role of EVs in biomarker discovery and therapeutics, which may help to develop early diagnosis and treatment of tobacco-induced renal injury in COVID-19 patients, respectively.

Graphical Abstract

CircRNA_0026344 via exosomal miR-21 regulation of Smad7 is involved in aberrant cross-talk of epithelium-fibroblasts during cigarette smoke-induced pulmonary fibrosis

For smoking-induced pulmonary fibrosis (PF), a serious disease endangering human health, there is no effective clinical treatment. Aberrant epithelium-fibroblast cross-talk is involved in formation of the excessive extracellular matrix (ECM) that contributes to PF. Circular RNAs have been associated with various pulmonary diseases. However, the mechanisms of circRNAs in PF are not clear. Herein, our goals were to investigate the involvement of circRNA_0026344 in the aberrant epithelium-fibroblast cross-talk induced by cigarette smoke (CS) and to define its mechanism. Chronic exposure (16 weeks) of BALB/c mice to 500 mg/m3 CS induced lung injury and fibrosis in lung tissues. From HBE cells, circRNA_0026344 was selected by microarray analysis and verified as that with the most severe down-regulation caused by cigarette smoke extract (CSE). The regulatory relationship between circRNA_0026344 and miR-21 was assessed by use of bioinformatics, RNA pull-down assays, and qRT-PCR. We found that miR-21 binding sites were present in circRNA_0026344 and, in HBE cells, it could act as a sponge for miR-21. When pcDNA3.0-circRNA_0026344, a high expression plasmid of circRNA_0026344, was transfected into HBE cells, the CSE-induced up-regulation of miR-21 levels was reversed. In MRC-5 cells, HBE-secreted exosomal miR-21 decreased levels of Smad7 and activated the TGF-β1/Smad3 pathway. By using the Targetscan database, the presence of species-conserved miR-21 binding sites in the Smad7 3'UTR region were predicted. We verified, by use of a luciferase reporter gene, that miR-21 bound to the 3'UTR region of Smad7 mRNA to inhibit its transcription. In conclusion, the results reveal that, in CS-induced pulmonary fibrosis, circRNA_0026344, via exosomal miR-21 regulation of Smad7, is involved in aberrant cross-talk of epithelium-fibroblasts. These results will be useful for the discovery of early biomarkers and for providing therapeutic targets for smoking-induced pulmonary fibrosis.

Serum‑derived exosomes from house dust mite‑sensitized guinea pigs contribute to inflammation in BEAS‑2B cells via the TLR4‑NF‑κB pathway

Airway epithelial cells, which are the first physical defense barrier against allergens, play a pivotal role in immunity, airway inflammation and airway remodeling. The damage and dysfunction of these cells trigger the development of airway inflammatory diseases. Exosomes, which exist in various bodily fluids, mediate cell-cell communication and participate in the immune response process. The present study aimed to investigate whether serum exosomes play a pro-inflammatory role in bronchial epithelial cells (BEAS-2B cells) and, if so, explore the underlying molecular mechanisms. A guinea pig model of House dust mite (HDM)-induced asthma was established by sensitizing the rodents with HDM and PBS, and serum-derived exosomes were harvested. It was found that serum-derived exosomes from HDM-sensitized guinea pigs displayed higher levels of exosomal markers than those from controls. Additionally, western blot analysis and reverse transcription-quantitative PCR indicated that serum-derived exosomes from HDM-sensitized guinea pigs carried heat shock protein 70 and triggered an inflammatory response in BEAS-2B cells via the toll-like receptor 4 (TLR4)-NF-κB pathway. However, TAK-242, an inhibitor of the expression of TLR4, blocked the activation of the TLR4-NF-κB pathway. These findings provided a novel mechanism for exosome-mediated inflammatory responses and a new perspective for the intervention of inflammatory airway disorders.

Extracellular Vesicles: A Novel Opportunity for Precision Medicine in Respiratory Diseases

Extracellular vesicles are membrane-bound nanoparticles secreted by cells which play a well-known role in cell to cell communication. The most update to date nomenclature categorizes extracellular vesicles based on their relative size, protein markers, and/or the cell type of origin. Extracellular vesicles can be isolated from biological fluids using a variety of methods, including but not limited to, ultrafiltration, size-exclusion chromatography, differential ultracentrifugation, density gradient centrifugation, precipitation-based methods, and immunoaffinity capture. These nanovesicles carry distinct “cargo,” made up of biomolecules such as nucleic acids, lipids, and protein, which is delivered to nearby target cells. The “cargo” profile carried by extracellular vesicles is critical in their role of communication and resembles the physiological status of the cell they originated from. For the purpose of this review, we will focus on the miRNA cargo. Extracellular vesicle-miRNA profiles hold the potential to be used in diagnostic panels for a variety of diseases through a novel method known as “liquid biopsy.” In addition to this, extracellular vesicles may serve as a potential method to deliver drugs to specific cells within the body. This mini-review provides background into what extracellular vesicles are, methods of isolating these nanoparticles, their potential use as a biomarker and drug delivery system for precision medicine, and a summary of the current literature covering the role of some extracellular vesicle-cargo's in various pulmonary diseases.

Role of Extracellular Vesicles in Compromising Cellular Resilience to Environmental Stressors

Extracellular vesicles (EVs), like exosomes, are nanosized membrane-enveloped vesicles containing different bioactive cargo, such as proteins, lipids, mRNA, miRNA, and other small regulatory RNAs. Cell-derived EVs, including EVs originating from stem cells, may capture components from damaged cells or cells impacted by therapeutic treatments. Interestingly, EVs derived from stem cells can be preconditioned to produce and secrete EVs with different therapeutic properties, particularly with respect to heat-shock proteins and other molecular cargo contents. This behavior is consistent with stem cells that also respond differently to various microenvironments. Heat-shock proteins play roles in cellular protection and mediate cellular resistance to radiotherapy, chemotherapy, and heat shock. This review highlights the possible roles EVs play in mediating cellular plasticity and survival when exposed to different physical and chemical stressors, with a special focus on the respiratory distress due to the air pollution.

Circ-RBMS1 Knockdown Alleviates CSE-Induced Apoptosis, Inflammation and Oxidative Stress via Up-Regulating FBXO11 Through miR-197-3p in 16HBE Cells

Background

Emerging evidence has reported that circular RNAs (circRNAs) are aberrantly expressed and act as significant regulators in pathological processes of chronic obstructive pulmonary disease (COPD). Here, the purpose of this article was to evaluate and clarify the biological functions and mechanism of circRNA single stranded interacting protein 1 (circ-RBMS1) in cigarette smoke (CS)-induced COPD.

Methods

Human bronchial epithelial cells 16HBE treated with or without cigarette smoke extract (CSE) were used in the experimental group in vitro. Levels of circ-RBMS1, microRNA (miR)-197-3p, and F-box only protein 11 (FBXO11) were detected using quantitative real-time polymerase chain reaction and Western blot. The present study used cell counting kit-8 (CCK-8), 5-ethynyl-2ʹ-deoxyuridine (EDU), flow cytometry and Western blot assays to determine the survival of 16HBE cells. The activity of interleukin (IL)-1β, tumor necrosis factor (TNF-α), malondialdehyde (MDA) and superoxide dismutase (SOD) was evaluated using the relative commercial kits. Dual-luciferase activity and RIP assays were used to identify the target relationship between miR-197-3p and circ-RBMS1 or FBXO11.

Results

Circ-RBMS1 was highly expressed in COPD patients, and CSE induced an increased expression of circ-RBMS1 in a dose-dependent manner. Functionally, knockdown of circ-RBMS1 attenuated CSE-induced apoptosis, inflammation and oxidative stress in 16HBE cells. Circ-RBMS1 directly targeted miR-197-3p, and miR-197-3p inhibition reversed the effects of circ-RBMS1 knockdown on CSE-induced 16HBE cells. FBXO11 was a target of miR-197-3p. MiR-197-3p overexpression or FBXO11 silencing reduced the apoptosis, inflammation and oxidative stress in CSE-induced 16HBE cells. Moreover, miR-197-3p exerted its effects by targeting FBXO11. Additionally, circ-RBMS1 acted as a sponge for miR-197-3p to positively regulate FBXO11 expression in 16HBE cells.

Conclusion

Circ-RBMS1 knockdown alleviated CSE-induced apoptosis, inflammation and oxidative stress in 16HBE cells via miR-197-3p/FBXO11 axis, suggesting a new insight into the pathogenesis of CS-induced COPD.

Exosomale microRNA-21 Promotes Keloid Fibroblast Proliferation and Collagen Production by inhibiting Smad7

In keloid fibroblasts, microRNA-21 (miR-21) enhances activation of the TGF-β-Smad-signaling pathway by downregulating Smad7 expression, thereby promoting keloid fibroblast proliferation and collagen production. However, it is unclear whether miR-21 performs the above-mentioned functions through exosomal transport. Here, we extracted exosomes from the culture supernatants of keloid and normal skin fibroblasts, and observed that exosomes from both cell types secreted exosomes; however, keloid fibroblasts secreted significantly more exosomal miR-21 than normal skin fibroblasts (P < 0.001). Interestingly, we also observed that exosomal miR-21 could enter target keloid fibroblasts. In addition, inhibiting exosomal miR-21 upregulated Smad7 protein expression and reduced Smad2 and Smad3 protein levels in target keloid fibroblasts. Furthermore, inhibiting exosomal miR-21 downregulated collagen I and collagen III expression in target keloid fibroblasts, increased the proportion of apoptotic cells, and reduced cell proliferation. Taken together, these results show that exosomal miR-21 promoted proliferation and collagen production in keloid fibroblasts by inhibiting Smad7. Thus, we identified regulatory roles for miR-21 in promoting keloid fibroblast proliferation and participating in keloid formation and development. These findings imply that miR-21 may serve as a novel target for controlling the development of keloids.

Potential Use of Exosomes as Diagnostic Biomarkers and in Targeted Drug Delivery: Progress in Clinical and Preclinical Applications

Exosomes are cell-derived vesicles containing heterogeneous active biomolecules such as proteins, lipids, mRNAs, receptors, immune regulatory molecules, and nucleic acids. They typically range in size from 30 to 150 nm in diameter. An exosome's surfaces can be bioengineered with antibodies, fluorescent dye, peptides, and tailored for small molecule and large active biologics. Exosomes have enormous potential as a drug delivery vehicle due to enhanced biocompatibility, excellent payload capability, and reduced immunogenicity compared to alternative polymeric-based carriers. Because of active targeting and specificity, exosomes are capable of delivering their cargo to exosome-recipient cells. Additionally, exosomes can potentially act as early stage disease diagnostic tools as the exosome carries various protein biomarkers associated with a specific disease. In this review, we summarize recent progress on exosome composition, biological characterization, and isolation techniques. Finally, we outline the exosome's clinical applications and preclinical advancement to provide an outlook on the importance of exosomes for use in targeted drug delivery, biomarker study, and vaccine development.

Exosomes in the pathogenesis and treatment of ocular diseases

Exosomes have diverse functions and rich content and are involved in intercellular communication, immune regulation, viral infection, tissue regeneration, and the occurrence, development and metastasis of tumours. Notably, various stem cell-derived exosomes are expected to become new therapeutic approaches for inflammatory diseases and tumours and have good clinical application prospects. However, few studies have examined exosomes in ophthalmic diseases. Therefore, based on the functions of exosomes, this paper summarizes progress in the possible use of exosomes as treatment for specific ophthalmic diseases, aiming to determine the pathogenesis of exosomes to achieve more effective clinical diagnosis and treatment of these diseases.

Comparative analysis of dietary exosome-derived microRNAs from human, bovine and caprine colostrum and mature milk

Mammalian milk including microRNAs (miRNAs) as a novel class of noncoding RNAs, that can be transferred to infants and it plays on a critical role in biological functions such as immune regulation and development. However, the origin and functional importance of milk-derived miRNAs are still undetermined. This study applied RNA sequencing to explore the featured profiles of miRNA expression in colostrum and mature milk-originated exosomes from human, bovine, and caprine milk. These dietary exosome-derived miRNAs are highly conserved in human, bovine and caprine milk. Interestingly, abundant miRNAs expressed in human milk are similarly conserved across species. In addition, we confirmed that immune-related miRNAs (miR-30a-5p, miR-22-3p, and miR-26a) are commonly observed in the colostrum and mature milk of cows and caprines as well as humans. Our results provide new insights and resources for investigating the functionality of immune-associated miRNAs and evaluating physiological and biological condition in human, bovine and caprine milk as biomarkers.

Cell-Selective Altered Cargo Properties of Extracellular Vesicles Following In Vitro Exposures to Intermittent Hypoxia

Intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with cardiovascular and metabolic dysfunction. However, the mechanisms underlying these morbidities remain poorly delineated. Extracellular vesicles (EVs) mediate intercellular communications, play pivotal roles in a multitude of physiological and pathological processes, and could mediate IH-induced cellular effects. Here, the effects of IH on human primary cells and the release of EVs were examined. Microvascular endothelial cells (HMVEC-d), THP1 monocytes, THP1 macrophages M0, THP1 macrophages M1, THP1 macrophages M2, pre-adipocytes, and differentiated adipocytes (HAd) were exposed to either room air (RA) or IH for 24 h. Secreted EVs were isolated and characterized using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. The effects of each of the cell-derived EVs on endothelial cell (EC) monolayer barrier integrity, on naïve THP1 macrophage polarity, and on adipocyte insulin sensitivity were also evaluated. IH did not alter EVs cell quantal release, but IH-EVs derived from HMVEC-d (p < 0.01), THP1 M0 (p < 0.01) and HAd (p < 0.05) significantly disrupted HMVEC-d monolayer integrity, particularly after H₂O₂ pre-conditioning. IH-EVs from HMVEC-d and THP1 M0 elicited M2-polarity changes did not alter insulin sensitivity responses. IH induces cell-selective changes in EVs cargo, which primarily seem to target the emergence of endothelial dysfunction. Thus, changes in EVs cargo from selected cell sources in vivo may play causal roles in some of the adverse outcomes associated with OSA.

Cigarette smoke extract-treated airway epithelial cells-derived exosomes promote M1 macrophage polarization in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a persistent respiratory disorder that is primarily caused by exposure to cigarette smoke (CS). Exosomes have emerged as crucial mediators of intercellular communication, but their role in CS-induced COPD is not fully understood. Here, we investigated whether exosomes derived from cigarette smoke extract (CSE)-treated mouse airway epithelial cells (MAECs) promote M1 macrophage polarization by upregulating triggering receptor expressed on myeloid cells-1 (TREM-1) expression during COPD pathogenesis. The exosomes isolated from PBS- or CSE-treated MAECs were named as Exo^PBS or Exo^CSE, respectively. Macrophages were transfected with si-TREM-1 to explore the role of TREM-1 in Exo^CSE-induced M1 macrophage polarization. The lentivirus expressing shTREM-1 was injected into COPD model mice by intranasal instillation, which was carried out to explore the in vivo role of TREM-1 in Exo^CSE-induced M1 macrophage polarization and CS-induced lung injury. We isolated Exo^PBS and Exo^CSE successfully, and found that Exo^CSE promoted M1 macrophage polarization. Furthermore, we found that the promotion of Exo^CSE to M1 macrophage polarization was partly reversed by TREM-1 knockdown. The results of animal experiments showed that Exo^CSE administration aggravated CS-induced impairment in pulmonary function, lung injury and M1 macrophage polarization, which were partly rescued by TREM-1 silencing. Overall, Exo^CSE promoted M1 macrophage polarization by upregulating TREM-1 expression, thereby aggravating the development of COPD.

Implications for Extracellular Matrix Interactions With Human Lung Basal Stem Cells in Lung Development, Disease, and Airway Modeling

The extracellular matrix (ECM) is not simply a quiescent scaffold. This three-dimensional network of extracellular macromolecules provides structural, mechanical, and biochemical support for the cells of the lung. Throughout life, the ECM forms a critical component of the pulmonary stem cell niche. Basal cells (BCs), the primary stem cells of the airways capable of differentiating to all luminal cell types, reside in close proximity to the basolateral ECM. Studying BC-ECM interactions is important for the development of therapies for chronic lung diseases in which ECM alterations are accompanied by an apparent loss of the lung's regenerative capacity. The complexity and importance of the native ECM in the regulation of BCs is highlighted as we have yet to create an in vitro culture model that is capable of supporting the long-term expansion of multipotent BCs. The interactions between the pulmonary ECM and BCs are, therefore, a vital component for understanding the mechanisms regulating BC stemness during health and disease. If we are able to replicate these interactions in airway models, we could significantly improve our ability to maintain basal cell stemness ex vivo for use in in vitro models and with prospects for cellular therapies. Furthermore, successful, and sustained airway regeneration in an aged or diseased lung by small molecules, novel compounds or via cellular therapy will rely upon both manipulation of the airway stem cells and their immediate niche within the lung. This review will focus on the current understanding of how the pulmonary ECM regulates the basal stem cell function, how this relationship changes in chronic disease, and how replicating native conditions poses challenges for ex vivo cell culture.

Overexpression of FOXA2 attenuates cigarette smoke-induced cellular senescence and lung inflammation through inhibition of the p38 and Erk1/2 MAPK pathways

Chronic obstructive pulmonary disease (COPD) is characterized by irreversible and progressive airflow limitation and encompasses varying degrees of chronic obstructive bronchitis and emphysema. Our previous study showed that Forkhead box protein A2 (FOXA2) is involved in cigarette smoke (CS)-induced squamous metaplasia. However, the contribution of FOXA2 activity to CS-induced cellular senescence and lung inflammation remains largely unknown. Here, we report that FOXA2 was underexpressed in CS-exposed mouse lungs, and decreased expression of FOXA2 was related to cell senescence and inflammation. Subsequent investigation suggested that FOXA2 is an anti-senescence factor in lung that is involved in inflammatory responses. Furthermore, FOXA2 overexpression delayed CSE-induced senescence and inflammation, which correlated with regulation of the p38 and Erk1/2 MAPK signaling pathways by CSE-induced FOXA2 downregulation. Collectivelly, these findings reveal a protective role for FOXA2 as a regulator of cell senescence and inflammation during COPD.

Dynamic evolution of emphysema and airway remodeling in two mouse models of COPD

Background

Establishment of a mouse model is important for investigating the mechanism of chronic obstructive pulmonary disease (COPD). In this study, we observed and compared the evolution of the pathology in two mouse models of COPD induced by cigarette smoke (CS) exposure alone or in combination with lipopolysaccharide (LPS).

Methods

One hundred eight wild-type C57BL/6 mice were equally divided into three groups: the (1) control group, (2) CS-exposed group (CS group), and (3) CS + LPS-exposed group (CS + LPS group). The body weight of the mice was recorded, and noninvasive lung function tests were performed monthly. Inflammation was evaluated by counting the number of inflammatory cells in bronchoalveolar lavage fluid and measuring the expression of the IL-6 mRNA in mouse lung tissue. Changes in pathology were assessed by performing hematoxylin and eosin and Masson staining of lung tissue sections.

Results

The two treatments induced emphysema and airway remodeling and decreased lung function. Emphysema was induced after 1 month of exposure to CS or CS + LPS, while airway remodeling was induced after 2 months of exposure to CS + LPS and 3 months of exposure to CS. Moreover, the mice in the CS + LPS group exhibited more severe inflammation and airway remodeling than the mice in the CS group, but the two treatments induced similar levels of emphysema.

Conclusion

Compared with the single CS exposure method, the CS + LPS exposure method is a more suitable model of COPD in airway remodeling research. Conversely, the CS exposure method is a more suitable model of COPD for emphysema research due to its simple operation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01456-z.

The μ-opioid receptor induces miR-21 expression and is ERK/PKCμ-dependent

Micro RNA-21 (miR-21) is believed to perform an important role in the transition from inflammation to resolution in the innate immune response. The biochemical basis for the induction of miR-21 remains uncertain. However, the activation of the μ-opioid receptor (MOR) induces the expression of miR-21. Our results show that human monocytes treated with μ-opioid agonists exhibit a significant increase in miR-21 expression. We found that MOR-induction of miR-21 requires the activation of the Ras-Raf-MEK-ERK signaling cascade, and to our surprise, the activation of PKCμ (PKD1). These results are significant given the role of miR-21 in the sensitivity to pain.

Extracellular Vesicle Associated Non-Coding RNAs in Lung Infections and Injury

Extracellular vesicles (EVs) refer to a heterogenous population of membrane-bound vesicles that are released by cells under physiological and pathological conditions. The detection of EVs in the majority of the bodily fluids, coupled with their diverse cargo comprising of DNA, RNA, lipids, and proteins, have led to the accumulated interests in leveraging these nanoparticles for diagnostic and therapeutic purposes. In particular, emerging studies have identified enhanced levels of a wide range of specific subclasses of non-coding RNAs (ncRNAs) in EVs, thereby suggesting the existence of highly selective and regulated molecular processes governing the sorting of these RNAs into EVs. Recent studies have also illustrated the functional relevance of these enriched ncRNAs in a variety of human diseases. This review summarizes the current state of knowledge on EV-ncRNAs, as well as their functions and significance in lung infection and injury. As a majority of the studies on EV-ncRNAs in lung diseases have focused on EV-microRNAs, we will particularly highlight the relevance of these molecules in the pathophysiology of these conditions, as well as their potential as novel biomarkers therein. We also outline the current challenges in the EV field amidst the tremendous efforts to propel the clinical utility of EVs for human diseases. The lack of published literature on the functional roles of other EV-ncRNA subtypes may in turn provide new avenues for future research to exploit their feasibility as novel diagnostic and therapeutic targets in human diseases.

Let-7 mediated airway remodelling in chronic obstructive pulmonary disease via the regulation of IL-6

BACKGROUND

Myofibroblast differentiation and extracellular matrix (ECM) deposition are observed in chronic obstructive pulmonary disease (COPD). However, the mechanisms of regulation of myofibroblast differentiation remain unclear.

MATERIALS AND METHODS

We detected let-7 levels in peripheral lung tissues, serum and primary bronchial epithelial cells of COPD patients and cigarette smoke (CS)-exposed mice. IL-6 mRNA was explored in lung tissues of COPD patients and CS-exposed mice. IL-6 protein was detected in cell supernatant from primary epithelial cells by ELISA. We confirmed the regulatory effect of let-7 on IL-6 by luciferase reporter assay. Western blotting assay was used to determine the expression of α-SMA, E-cadherin and collagen I. In vitro, cell study was performed to demonstrate the role of let-7 in myofibroblast differentiation and ECM deposition.

RESULTS

Low expression of let-7 was observed in COPD patients, CS-exposed mice and CS extract (CSE)-treated human bronchial epithelial (HBE) cells. Increased IL-6 was found in COPD patients, CS-exposed mice and CSE-treated HBE cells. Let-7 targets and silences IL-6 protein coding genes through binding to 3' untranslated region (UTR) of IL-6. Normal or CSE-treated HBE cells were co-cultured with human embryonic lung fibroblasts (MRC-5 cells). Reduction of let-7 in HBE cells caused myofibroblast differentiation and ECM deposition, while increase of let-7 mimics decreased myofibroblast differentiation phenotype and ECM deposition.

CONCLUSION

We demonstrate that CS reduced let-7 expression in COPD and, further, identify let-7 as a regulator of myofibroblast differentiation through the regulation of IL-6, which has potential value for diagnosis and treatment of COPD.

Protective effects of total flavonoids from Qu Zhi Qiao (fruit of Citrus paradisi cv. Changshanhuyou) on OVA-induced allergic airway inflammation and remodeling through MAPKs and Smad2/3 signaling pathway

Allergic asthma is one of the inflammatory diseases, which has become a major public health problem. Qu zhi qiao (QZQ), a dry and immature fruit of Citrus paradisi cv. Changshanhuyou, has various flavonoids with pharmacological properties. However, there is a knowledge gap on the pharmacological properties of QZQ on allergic asthma. Therefore, here, we explored the efficacy and mechanism of total flavonoids from QZQ (TFCH) on allergic asthma. We extracted and purified TFCH and conducted animal experiments using an Ovalbumin (OVA)-induced mice model. Bronchoalveolar lavage fluid and Swiss-Giemsa staining were used to count different inflammatory cells in allergic asthma mice. We conducted histopathology and immunohistochemistry to evaluate the changes in the lungs of allergic asthma mice. Moreover, we used ELISA assays to analyze chemokines and inflammatory cytokines. Furthermore, western blot analyses were conducted to elucidate the mechanism of TFCH on allergic asthma. We established that TFCH has anti-inflammatory effects and inhibits airway remodeling, providing a potential therapeutic strategy for allergic asthma.

Cigarette smoke extract induces pyroptosis in human bronchial epithelial cells through the ROS/NLRP3/caspase-1 pathway

AIMS

Pyroptosis and inflammation are involved in the development of chronic obstructive pulmonary disease (COPD). However, the cigarette smoke-mediated mechanism of COPD remains unclear. In this study, we aimed to investigate the role of nucleotide-binding domain-like receptor protein-3 (NLRP3) inflammasome-mediated pyroptosis in the death of human bronchial epithelial (HBE) cells after cigarette smoke extract (CSE) exposure.

MAIN METHODS

The protein level of NLRP3 in lung tissue was measured after cigarette smoke exposure in vivo. In vitro, HBE cells were treated with CSE. Subsequently, the activity of caspase-1, lactate dehydrogenase (LDH) release, release of interleukin (IL)-1β and NLRP3 expression levels were measured. The involvement of reactive oxygen species (ROS) was also explored.

KEY FINDINGS

After exposure to CSE, increased release of LDH, the transcriptional and translational upregulation of NLRP3, the caspase-1 activity levels, and enhanced IL-1β and IL-18 release were observed in 16HBE cells. In addition, NLRP3 was required to activate the caspase-1. Our results suggested that pre-stimulated of 16HBE with a caspase-1 inhibitor, or using NLRP3 siRNA to silence NLRP3 expression, also caused the decrease of IL-1β release and pyroptosis.

SIGNIFICANCES

CSE induced inflammation and contributed to pyroptosis through the ROS/NLRP3/caspase-1 pathway in 16HBE cells. The NLRP3 inflammasome participates in CSE-induced HBE cell damage and pyroptosis, which could provide new insights into COPD.

Role of extracellular vesicles in chronic lung disease

To explore the role of extracellular vesicles (EVs) in chronic lung diseases.

EVs are emerging as mediators of intercellular communication and possible diagnostic markers of disease. EVs harbour cargo molecules including RNA, lipids and proteins that they transfer to recipient cells. EVs are intercellular communicators within the lung microenvironment. Due to their disease-specific cargoes, EVs have the promise to be all-in-one complex multimodal biomarkers. EVs also have potential as drug carriers in chronic lung disease.

Descriptive discussion of key studies of EVs as contributors to disease pathology, as biomarkers and as potential therapies with a focus on chronic obstructive pulmonary disorder (COPD), cystic fibrosis (CF), asthma, idiopathic pulmonary fibrosis and lung cancer.

We provide a broad overview of the roles of EV in chronic respiratory disease. Recent advances in profiling EVs have shown their potential as biomarker candidates. Further studies have provided insight into their disease pathology, particularly in inflammatory processes across a spectrum of lung diseases. EVs are on the horizon as new modes of drug delivery and as therapies themselves in cell-based therapeutics.

EVs are relatively untapped sources of information in the clinic that can help further detail the full translational nature of chronic lung disorders.

METTL3-mediated m6A modification of ZBTB4 mRNA is involved in the smoking-induced EMT in cancer of the lung

N6-methyladenosine (m6A) is an epigenetic modification associated with various tumors, but its role in tumorigenesis remains unexplored. Here, as confirmed by methylated RNA immunoprecipitation sequencing (meRIP-seq) and RNA sequencing (RNA-seq) analyses, exposure of human bronchial epithelial (HBE) cells to cigarette smoke extract (CSE) caused an m6A modification in the 3' UTR of ZBTB4, a transcriptional repressor. For these cells, CSE also elevated methyltransferase-like 3 (METTL3) levels, which increased the m6A modification of ZBTB4. RIP-qPCR illustrated that ZBTB4 was the intent gene of YTHDF2 and that levels of ZBTB4 were decreased in an YTHDF2-dependent mechanism. The lower levels of ZBTB4 were associated with upregulation of EZH2, which enhanced H3K27me3 combining with E-cadherin promoter, causing lower E-cadherin levels and induction of the epithelial-mesenchymal transition (EMT). Further, in the lungs of mice, downregulation of METTL3 alleviated the cigarette smoke (CS)-induced EMT. Further, the expression of METTL3 was high in the lung tissues of smokers and inversely correlated with ZBTB4. Overall, our results show that the METTL3-mediated m6A modification of ZBTB4 via EZH2 is involved in the CS-induced EMT and in lung cancer. These results indicate that m6A modifications are a potential therapeutic target of lung damage induced by CS.

The aberrant cross-talk of epithelium-macrophages via METTL3-regulated extracellular vesicle miR-93 in smoking-induced emphysema

Cigarette smoke (CS), a complex chemical indoor air pollutant, induces degradation of elastin, resulting in emphysema. Aberrant cross-talk between macrophages and bronchial epithelial cells is essential for the degradation of elastin that contributes to emphysema, in which extracellular vesicles (EVs) play a critical role. The formation of N6-methyladenosine (m6A) is a modification in miRNA processing, but its role in the development of emphysema remains unclear. Here, we established that production of excess mature microRNA-93 (miR-93) in bronchial epithelial cells via enhanced m6A modification was mediated by overexpressed methyltransferase-like 3 (METTL3) induced by CS. Mature miR-93 was transferred from bronchial epithelial cells into macrophages by EVs. In macrophages, miR-93 activated the JNK pathway by targeting dual-specificity phosphatase 2 (DUSP2), which elevated the levels of matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 12 (MMP12) and induced elastin degradation, leading to emphysema. These results demonstrate that METTL3-mediated formation of EV miR-93, facilitated by m6A, is implicated in the aberrant cross-talk of epithelium-macrophages, indicating that this process is involved in the smoking-related emphysema. EV miR-93 may use as a novel risk biomarker for CS-induced emphysema.