Lung-Derived Exosomal miR-483-3p Regulates the Innate Immune Response to Influenza Virus Infection

MiR-483-3p promotes dental pulp stem cells osteogenic differentiation via the MAPK signaling pathway by targeting ARRB2

Human dental pulp stem cells (DPSCs) have become an important component for bone tissue engineering and regenerative medicine due to their ability to differentiate into osteoblast precursors. Two miRNA chip datasets (GSE138180 and E-MTAB-3077) of DPSCs osteogenic differentiation were analyzed respectively to find the expression of miR-483-3p significantly increased in the differentiated groups. We further confirmed that miR-483-3p continued to overexpress during osteogenic differentiation of DPSCs, especially reaching its peak on the 7th day. Moreover, miR-483-3p could significantly promote the expression of osteogenic markers including RUNX2 and OSX, and activate MAPK signaling pathway by inducing phosphorylation of ERK, p38, and JNK. In addition, as a significant gene within the MAPK signaling pathway, ARRB2 was identified as the target gene of miR-483-3p by bioinformatic prediction and experimental verification. In conclusion, we identified miR-483-3p could promote osteogenic differentiation of DPSCs via the MAPK signaling pathway by targeting ARRB2.

Systematic review and meta-analysis of genome-wide pooled CRISPR screens to identify host factors involved in influenza A virus infection

The host-virus interactome is increasingly recognized as an important research field to discover new therapeutic targets to treat influenza. Multiple pooled genome-wide CRISPR-Cas screens have been reported to identify new pro- and antiviral host factors of the influenza A virus. However, at present, a comprehensive summary of the results is lacking. We performed a systematic review of all reported CRISPR studies in this field in combination with a meta-analysis using the algorithm of meta-analysis by information content (MAIC). Two ranked gene lists were generated based on evidence in 15 proviral and 4 antiviral screens. Enriched pathways in the proviral MAIC results were compared to those of a prior array-based RNA interference (RNAi) meta-analysis. The top 50 proviral MAIC list contained genes whose role requires further elucidation, such as the endosomal ion channel TPCN1 and the kinase WEE1. Moreover, MAIC indicated that ALYREF, a component of the transcription export complex, has antiviral properties, whereas former knockdown experiments attributed a proviral role to this host factor. CRISPR-Cas-pooled screens displayed a bias toward early-replication events, whereas the prior RNAi meta-analysis covered early and late-stage events. RNAi screens led to the identification of a larger fraction of essential genes than CRISPR screens. In summary, the MAIC algorithm points toward the importance of several less well-known pathways in host-influenza virus interactions that merit further investigation. The results from this meta-analysis of CRISPR screens in influenza A virus infection may help guide future research efforts to develop host-directed anti-influenza drugs.

IMPORTANCE

Viruses rely on host factors for their replication, whereas the host cell has evolved virus restriction factors. These factors represent potential targets for host-oriented antiviral therapies. Multiple pooled genome-wide CRISPR-Cas screens have been reported to identify pro- and antiviral host factors in the context of influenza virus infection. We performed a comprehensive analysis of the outcome of these screens based on the publicly available gene lists, using the recently developed algorithm meta-analysis by information content (MAIC). MAIC allows the systematic integration of ranked and unranked gene lists into a final ranked gene list. This approach highlighted poorly characterized host factors and pathways with evidence from multiple screens, such as the vesicle docking and lipid metabolism pathways, which merit further exploration.

Exosome-mediated regulation of inflammatory pathway during respiratory viral disease

Viruses have developed many mechanisms by which they can stimulate or inhibit inflammation and cause various diseases, including viral respiratory diseases that kill many people every year. One of the mechanisms that viruses use to induce or inhibit inflammation is exosomes. Exosomes are small membrane nanovesicles (30-150 nm) released from cells that contain proteins, DNA, and coding and non-coding RNA species. They are a group of extracellular vesicles that cells can take up to produce and mediate communication. Intercellular effect exosomes can deliver a broad confine of biological molecules, containing nucleic acids, proteins, and lipids, to the target cell, where they can convey therapeutic or pathogenic consequences through the modulation of inflammation and immune processes. Recent research has shown that exosomes can deliver entire virus genomes or virions to distant target cells, then the delivered viruses can escape the immune system and infect cells. Adenoviruses, orthomyxoviruses, paramyxoviruses, respiratory syncytial viruses, picornaviruses, coronaviruses, and rhinoviruses are mostly related to respiratory diseases. In this article, we will first discuss the current knowledge of exosomes. We will learn about the relationship between exosomes and viral infections, and We mention the inflammations caused by viruses in the airways, the role of exosomes in them, and finally, we examine the relationship between the viruses as mentioned earlier, and the regulation of inflammatory pathways that play a role in causing the disease.

RNF5: inhibiting antiviral immunity and shaping virus life cycle

RNF5 is an E3 ubiquitin ligase involved in various physiological processes such as protein localization and cancer progression. Recent studies have shown that RNF5 significantly inhibits antiviral innate immunity by promoting the ubiquitination and degradation of STING and MAVS, which are essential adaptor proteins, as well as their downstream signal IRF3. The abundance of RNF5 is delicately regulated by both host factors and viruses. Host factors have been found to restrict RNF5-mediated ubiquitination, maintaining the stability of STING or MAVS through distinct mechanisms. Meanwhile, viruses have developed ingenious strategies to hijack RNF5 to ubiquitinate and degrade immune proteins. Moreover, recent studies have revealed the multifaceted roles of RNF5 in the life cycle of various viruses, including SARS-CoV-2 and KSHV. Based on these emerging discoveries, RNF5 represents a novel means of modulating antiviral immunity. In this review, we summarize the latest research on the roles of RNF5 in antiviral immunity and virus life cycle. This comprehensive understanding could offer valuable insights into exploring potential therapeutic applications focused on targeting RNF5 during viral infections.

Extracellular Vesicles and Their Role in Lung Infections

Lung infections are one of the most common causes of death and morbidity worldwide. Both bacterial and viral lung infections cause a vast number of infections with varying severities. Extracellular vesicles (EVs) produced by different cells due to infection in the lung have the ability to modify the immune system, leading to either better immune response or worsening of the disease. It has been shown that both bacteria and viruses have the ability to produce their EVs and stimulate the immune system for that. In this review, we investigate topics from EV biogenesis and types of EVs to lung bacterial and viral infections caused by various bacterial species. Mycobacterium tuberculosis, Staphylococcus aureus, and Streptococcus pneumoniae infections are covered intensively in this review. Moreover, various viral lung infections, including SARS-CoV-2 infections, have been depicted extensively. In this review, we focus on eukaryotic-cell-derived EVs as an important component of disease pathogenesis. Finally, this review holds high novelty in its findings and literature review. It represents the first time to cover all different information on immune-cell-derived EVs in both bacterial and viral lung infections.

Cold exposure impairs extracellular vesicle swarm-mediated nasal antiviral immunity

BACKGROUND

The human upper respiratory tract is the first site of contact for inhaled respiratory viruses and elaborates an array of innate immune responses. Seasonal variation in respiratory viral infections and the importance of ambient temperature in modulating immune responses to infections have been well recognized; however, the underlying biological mechanisms remain understudied.

OBJECTIVE

We investigated the role of nasal epithelium-derived extracellular vesicles (EVs) in innate Toll-like receptor 3 (TLR3)-dependent antiviral immunity.

METHODS

We evaluated the secretion and composition of nasal epithelial EVs after TLR3 stimulation in human autologous cells and fresh human nasal mucosal surgical specimens. We also explored the antiviral activity and mechanisms of TLR3-stimulated EVs against respiratory viruses as well as the effect of cool ambient temperature on TLR3-dependent antiviral immunity.

RESULTS

We found that polyinosinic:polycytidylic acid, aka poly(I:C), exposure induced a swarm-like increase in the secretion of nasal epithelial EVs via the TLR3 signaling. EVs participated in TLR3-dependent antiviral immunity, protecting the host from viral infections through both EV-mediated functional delivery of miR-17 and direct virion neutralization after binding to virus ligands via surface receptors, including LDLR and ICAM-1. These potent antiviral immune defense functions mediated by TLR3-stimulated EVs were impaired by cold exposure via a decrease in total EV secretion as well as diminished microRNA packaging and antiviral binding affinity of individual EV.

CONCLUSION

TLR3-dependent nasal epithelial EVs exhibit multiple innate antiviral mechanisms to suppress respiratory viral infections. Furthermore, our study provides a direct quantitative mechanistic explanation for seasonal variation in upper respiratory tract infection prevalence.

Impact of extracellular vesicles on the pathogenesis, diagnosis, and potential therapy in cardiopulmonary disease

Cardiopulmonary diseases span a wide breadth of conditions affecting both heart and lung, the burden of which is globally significant. Chronic pulmonary disease and cardiovascular disease are two of the leading causes of morbidity and mortality worldwide. This makes it critical to understand disease pathogenesis, thereby providing new diagnostic and therapeutic avenues to improve clinical outcomes. Extracellular vesicles provide insight into all three of these features of the disease. Extracellular vesicles are membrane-bound vesicles released by a multitude, if not all, cell types and are involved in multiple physiological and pathological processes that play an important role in intercellular communication. They can be isolated from bodily fluids, such as blood, urine, and saliva, and their contents include a variety of proteins, proteases, and microRNA. These vesicles have shown to act as effective transmitters of biological signals within the heart and lung and have roles in the pathogenesis and diagnosis of multiple cardiopulmonary diseases as well as demonstrate potential as therapeutic agents to treat said conditions. In this review article, we will discuss the role these extracellular vesicles play in the diagnosis, pathogenesis, and therapeutic possibilities of cardiovascular, pulmonary, and infection-related cardiopulmonary diseases.

Exosomes Released by Influenza-Virus-Infected Cells Carry Factors Capable of Suppressing Immune Defense Genes in Naïve Cells

Background: Exosomes are involved in intercellular communication and can transfer regulatory molecules between cells. Consequently, they can participate in host immune response regulation. For the influenza A virus (IAV), there is very limited information on changes in exosome composition during cell infection shedding light on the potential role of these extracellular membrane vesicles. Thus, the aim of our work was to study changes in exosomal composition following IAV infection of cells, as well as to evaluate their effect on uninfected cells. Methods: To characterize changes in the composition of cellular miRNAs and mRNAs of exosomes during IAV infection of A549 cells, NGS was used, as well as PCR to identify viral genes. Naïve A549 cells were stimulated with infected-cell-secreted exosomes for studying their activity. Changes in the expression of genes associated with the cell's immune response were shown using PCR. The effect of exosomes on IAV replication was shown in MDCK cells using In-Cell ELISA and PCR of the supernatants. Results: A change in the miRNA composition (miR-21-3p, miR-26a-5p, miR-23a-5p, miR-548c-5p) and mRNA composition (RPL13A, MKNK2, TRIB3) of exosomes under the influence of the IAV was shown. Many RNAs were involved in the regulation of the immune response of the cell, mainly by suppressing it. After exosome stimulation of naïve cells, a significant decrease in the expression of genes involved in the immune response was shown (RIG1, IFIT1, MDA5, COX2, NFκB, AnxA1, PKR, IL6, IL18). When infecting MDCK cells, a significant decrease in nucleoprotein levels was observed in the presence of exosomes secreted by mock-infected cells. Viral levels in supernatants also decreased. Conclusions: Exosomes secreted by IAV-infected cells could reduce the immune response of neighboring intact cells, leading to more effective IAV replication. This may be associated both with regulatory functions of cellular miRNAs and mRNAs carried by exosomes, or with the presence of viral mRNAs encoding proteins with an immunosuppressive function.

Serum-derived exosomes induce proinflammatory cytokines production in Cynoglossus semilaevis via miR-133-3p

Exosomes are small membrane-enclosed vesicles secreted by various types of cells. In mammals, a wide range of physiological and pathological functions have been confirmed and attributed to EVs carrying a variety of molecular cargoes, including miRNAs. However, studies on the biological functions and related molecular mechanisms of serum exosomes isolated from teleost fish are limited. Indeed, the molecular mechanisms underlying the effects of serum exosomes on immune responses and inflammatory processes are unknown. Chinese tongue sole (Cynoglossus semilaevis) is an economically important species used widely in industrial aquaculture. Vibrio harveyi, a common bacterial pathogen that infects C. semilaevis and some other fish, causes excessive inflammatory reactions, which are characterized by skin ulceration. Here, we isolated serum-derived exosomes from C. semilaevis and investigated their effects on inflammatory processes following V. harveyi infection. We found that compared with uninfected fish, exosome abundance in infected fish blood increased with bacterial infection time, while expression of TNF-α increased, and that of IL-10 decreased, significantly. Moreover, artificial infection studies demonstrated that injection of serum exosomes isolated from infected fish increased expression of TNF-α, IL-6, and IL-8, which is consistent with the increase in proinflammatory cytokines induced by V. harveyi infection. To further investigate the mechanisms by which exosomes increase proinflammatory cytokine production, we performed miRNA expression profiling and found that 26 differentially expressed miRNAs were associated with bacterial infection and immune responses; of these, miR-133-3p was considerably more abundant in serum exosomes from infected fish. Bioinformatics analysis suggested that miR-133-3p inhibits NF-κB signaling pathways by targeting PP2A and affecting cytokine release. We also found that miR-133-3p increased expression of TNF-α, IL-6, and IL-8 in fish blood and kidney, whereas an miR-133-3p inhibitor showed the opposite results. Thus, the data suggest that serum exosomes participate in innate immunity in teleost fish by promoting inflammatory responses to bacterial infection. Exosome-mediated transfer of miR-133-3p increases expression of proinflammatory cytokines in C. semilaevis, resulting in excessive inflammatory responses during V. harveyi infection. These data may lead to development of methods and strategies that control skin ulceration in Chinese tongue sole.

Extracellular Vesicles: A Novel Tool in Nanomedicine and Cancer Treatment

Simple Summary

Extracellular vesicles (EVs) are plasma-membrane-encased particles with various biomolecules. Recent studies have demonstrated that EVs play a role in homeostasis and disease progression, and therefore may be important disease biomarkers. In cancer, EVs mediate inflammatory responses, oxidative stress, and contribute to altering the microenvironment. Additionally, EVs function as mediators in neurodegenerative diseases. Interestingly, EVs also promote stem cell differentiation, intercellular communication, and wound healing. These functions suggest that EVs can be utilized in medicine as therapeutic tools. Moreover, their endogenous nature and ability to carry intact biomolecules of different sizes to their target site due to their lipid bilayer makes them perfect drug transport systems that can be utilized in the treatment of many diseases, with higher efficacy and fewer side effects than other treatments as they can only target diseased cells and not healthy nearby cells, which occurs in conventional chemotherapy, for example. As such, their role in drug delivery has great potential.

Abstract

Extracellular vesicles are membrane-bound vesicles released by cells to mediate intercellular communication and homeostasis. Various external stimuli as well as inherent abnormalities result in alterations in the extracellular vesicle milieu. Changes to cells result in alterations in the content of the extracellular vesicle biogenesis, which may affect proximal and distal cells encountering these altered extracellular vesicles. Therefore, the examination of changes in the extracellular vesicle signature can be used to follow disease progression, reveal possible targets to improve therapy, as well as to serve as mediators of therapy. Furthermore, recent studies have developed methods to alter the cargo of extracellular vesicles to restore normal function or deliver therapeutic agents. This review will examine how extracellular vesicles from cancer cells differ from normal cells, how these altered extracellular vesicles can contribute to cancer progression, and how extracellular vesicles can be used as a therapeutic agent to target cancer cells and cancer-associated stroma. Here we present extracellular vesicles as a novel tool in nanomedicine.

Materials‐based vaccines for infectious diseases

Infectious diseases that result from pathogen infection are among the leading causes of human death, with pathogens such as human immunodeficiency virus, malaria, influenza, and ongoing SARS‐COV‐2 viruses constantly threatening the global population. While the mechanisms behind various infectious diseases are not entirely clear and thus retard the development of effective therapeutics, vaccines have served as a universal approach to containing infectious diseases. However, conventional vaccines that solely consist of antigens or simply mix antigens and adjuvants have failed to control various highly infective or deadly pathogens. Biomaterials‐based vaccines have provided a promising solution due to their ability to synergize the function of antigens and adjuvants, troubleshoot delivery issues, home and manipulate immune cells in situ. In this review, we will summarize different types of materials‐based vaccines for generating cellular and humoral responses against pathogens and discuss the design criteria for amplifying the efficacy of materials‐based vaccines against infectious diseases.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease

SARS-CoV-2 and extracellular vesicles: An intricate interplay in pathogenesis, diagnosis and treatment

Extracellular vesicles (EVs) are widely recognized as intercellular communication mediators. Among the different biological processes, EVs play a role in viral infections, supporting virus entrance and spread into host cells and immune response evasion. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection became an urgent public health issue with significant morbidity and mortality worldwide, being responsible for the current COVID-19 pandemic. Since EVs are implicated in SARS-CoV-2 infection in a morphological and functional level, they have gained growing interest for a better understanding of SARS-CoV-2 pathogenesis and represent possible diagnostic tools to track the disease progression. Furthermore, thanks to their biocompatibility and efficient immune activation, the use of EVs may also represent a promising strategy for the development of new therapeutic strategies against COVID-19. In this review, we explore the role of EVs in viral infections with a focus on SARS-CoV-2 biology and pathogenesis, considering recent morphometric studies. The common biogenesis aspects and structural similarities between EVs and SARS-CoV-2 will be examined, offering a panoramic of their multifaceted interplay and presenting EVs as a machinery supporting the viral cycle. On the other hand, EVs may be exploited as early diagnostic biomarkers and efficient carriers for drug delivery and vaccination, and ongoing studies will be reviewed to highlight EVs as potential alternative therapeutic strategies against SARS-CoV-2 infection.

Potential of MicroRNAs As Biomarkers and Therapeutic Targets in Respiratory Viruses: A Literature Review

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression through recognition of cognate sequences and interference of transcriptional, translational, or epigenetic processes. Hundreds of miRNA genes have been found in diverse viruses, and many of these are phylogenetically conserved. Respiratory viruses are the most frequent causative agents of disease in humans, with a significant impact on morbidity and mortality worldwide. Recently, the role of miRNAs in respiratory viral gene regulation, as well as host gene regulation during disease progression, has become a field of interest. This review highlighted the importance of various miRNAs and their potential role in fighting with respiratory viruses as therapeutic molecules with a focus on COVID-19.

Diagnostic Potential of Plasma Extracellular Vesicle miR-483-3p and Let-7d-3p for Sepsis

Background: microRNAs (miRNAs) from circulating extracellular vesicles (EVs) have been reported as disease biomarkers. This study aimed to identify the diagnostic value of plasma EV-miRNAs in sepsis.

Methods: EVs were separated from the plasma of sepsis patients at admission and healthy controls. The expression of EV-miRNAs was evaluated by microarray and qRT-PCR.

Results: A preliminary miRNA microarray of plasma EVs from a discovery cohort of 3 sepsis patients at admission and three healthy controls identified 11 miRNAs with over 2-fold upregulation in sepsis group. Based on this finding, EV samples from a validation cohort of 37 sepsis patients at admission and 25 healthy controls were evaluated for the expression of the 6 miRNAs relating injury and inflammation via qRT-PCR. Elevated expression of miR-483-3p and let-7d-3p was validated in sepsis patients and corroborated in a mouse model of sepsis. miR-483-3p and let-7d-3p levels positively correlated with the disease severity. Additionally, a combination of miR-483-3p and let-7d-3p had diagnostic value for sepsis. Furthermore, bioinformatic analysis and experimental validation showed that miR-483-3p and let-7d-3p target pathways regulating immune response and endothelial function.

Conclusion: The present study reveals the potential role of plasma EV-miRNAs in the pathogenesis of sepsis and the utility of combining miR-483-3p and let-7d-3p as biomarkers for early sepsis diagnosis.

Functional Roles of Non-coding RNAs in the Interaction Between Host and Influenza A Virus

Non-coding RNAs (ncRNAs) are extensively expressed in various cells and tissues, and studies have shown that ncRNAs play significant roles in cell regulation. However, in the past few decades, the knowledge of ncRNAs has been increased dramatically due to their transcriptional ability and multiple regulatory functions. Typically, regulatory ncRNAs include long ncRNAs (lncRNAs), miRNAs, piRNAs, Y RNAs, vault RNAs, and circular RNAs (circRNAs), etc. Previous studies have revealed that various ncRNAs are involved in the host responses to virus infection and play critical roles in the regulation of host-virus interactions. In this review, we discuss the conceptual framework and biological regulations of ncRNAs to elucidate their functions in response to viral infection, especially influenza A virus (IAV) infection. In addition, we summarize the ncRNAs that are associated with innate immunity and involvement of interferons and their stimulated genes (ISGs) during IAV infection.

The potential use of microRNAs as a therapeutic strategy for SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To date, there is no effective therapeutic approach for treating SARS-CoV-2 infections. MicroRNAs (miRNAs) have been recognized to target the viral genome directly or indirectly, thereby inhibiting viral replication. Several studies have demonstrated that host miRNAs target different sites in SARS-CoV-2 RNA and constrain the production of essential viral proteins. Furthermore, miRNAs have lower toxicity, are more immunogenic, and are more diverse than protein-based and even plasmid-DNA-based therapeutic agents. In this review, we emphasize the role of miRNAs in viral infection and their potential use as therapeutic agents against COVID-19 disease. The potential of novel miRNA delivery strategies, especially EDV™ nanocells, for targeting lung tissue for treatment of SARS-CoV-2 infection is also discussed.

The clinical role of host and bacterial-derived extracellular vesicles in pneumonia

Pneumonia is among the leading causes of morbidity and mortality worldwide. Due to constant evolution of respiratory bacteria and viruses, development of drug resistance and emerging pathogens, it constitutes a considerable health care threat. To enable development of novel strategies to control pneumonia, a better understanding of the complex mechanisms of interaction between host cells and infecting pathogens is vital. Here, we review the roles of host cell and bacterial-derived extracellular vesicles (EVs) in these interactions. We discuss clinical and experimental as well as pathogen-overarching and pathogen-specific evidence for common viral and bacterial elicitors of community- and hospital-acquired pneumonia. Finally, we highlight the potential of EVs for improved management of pneumonia patients and discuss the translational steps to be taken before they can be safely exploited as novel vaccines, biomarkers, or therapeutics in clinical practice.

The role of exosomes from BALF in lung disease

Exosomes are released from a variety of immune cells and nonimmune cells, the phospholipid vesicle bilayer membrane structure actively secreted into tissues. Recently, exosomes were demonstrated to be effectively delivered proteins, cholesterol, lipids, and amounts of DNA, mRNA, and noncoding RNAs to a target cell or tissue from a host cell. These can be detected in blood, urine, exhaled breath condensates, bronchoalveolar lavage fluid (BALF), ascites, and cerebrospinal fluid. BALF is a clinical examination method for obtaining alveolar cells and biochemical components, reflecting changes in the lungs, so it is also called liquid biopsy. Exosomes from BALF become a new method for intercellular communication and well‐documented in various pulmonary diseases. In chronic obstructive pulmonary disease (COPD), BALF exosomes can predict the degree of COPD damage and serve as an effective monitoring indicator for airflow limitation and airway remodeling. It also mediates antigen presentation in the airways to the adaptive immune system as well as costimulatory effects. Furthermore, BALF exosomes from acute lung injury and infective diseases are closely related to various infections and lack of oxygen status. BALF exosomes play an important role in the diagnosis and prognosis of lung cancer. The effect of immunomodulatory role for BALF exosomes in adaptive and innate immune responses has been studied in sarcoidosis. The intercellular communication in the microenvironment of BALF exosomes in pulmonary fibrosis and lung remodeling have been studied. In this review, we summarize the novel findings of exosomes in BALF, executed function by protein, miRNA, DNA cytokine, and so on in several pulmonary diseases.

Lung-derived exosomes regulate the function of mesenchymal stem cells and alleviate phosgene-induced lung injury via miR-34c-3p

Phosgene may induce acute lung injury (ALI) when a person is exposed to it. Mesenchymal stem cells (MSCs) were affirmed to have therapeutic effects on phosgene-induced ALI. In a previous study, ALI exosomes have been confirmed to promote the proliferation and migration of MSCs. However, the mechanism of this phenomenon is still unclear. MicroRNAs (miRNAs) are essential in the physiological process of cells. In this study, lung-derived exosomes were isolated from phosgene-exposed and normal rats, respectively, through ultracentrifugation and cultured MSCs with these exosomes. We found that rno-miR-34c-3p was downregulated in MSCs cocultured with ALI exosomes. MiR-34c-3p inhibitor promoted the proliferation and migration of MSCs. Moreover, the dual-luciferase reporter assay demonstrated that miR-34c-3p regulated Janus kinase 1 (JAK1) expression. The miR-34c-3p inhibitor also significantly activated the JAK1/signal transducer and activator of transcription 3 (STAT3) signaling pathway. In conclusion, ALI exosomes decrease the miR-34c-3p expression levels, influencing MSCs via the JAK1/STAT3 signaling pathway.

Exosome-Based Vaccines: History, Current State, and Clinical Trials

Extracellular vesicles (EVs) are released by most cell types as part of an intracellular communication system in crucial processes such as inflammation, cell proliferation, and immune response. However, EVs have also been implicated in the pathogenesis of several diseases, such as cancer and numerous infectious diseases. An important feature of EVs is their ability to deliver a wide range of molecules to nearby targets or over long distances, which allows the mediation of different biological functions. This delivery mechanism can be utilized for the development of therapeutic strategies, such as vaccination. Here, we have highlighted several studies from a historical perspective, with respect to current investigations on EV-based vaccines. For example, vaccines based on exosomes derived from dendritic cells proved to be simpler in terms of management and cost-effectiveness than dendritic cell vaccines. Recent evidence suggests that EVs derived from cancer cells can be leveraged for therapeutics to induce strong anti-tumor immune responses. Moreover, EV-based vaccines have shown exciting and promising results against different types of infectious diseases. We have also summarized the results obtained from completed clinical trials conducted on the usage of exosome-based vaccines in the treatment of cancer, and more recently, coronavirus disease.

Exosome therapeutics for COVID-19 and respiratory viruses

Respiratory viral diseases are a leading cause of mortality in humans. They have proven to drive pandemic risk due to their complex transmission factors and viral evolution. However, the slow production of effective antiviral drugs and vaccines allows for outbreaks of these diseases, emphasizing a critical need for refined antiviral therapeutics. The delivery of exosomes, a naturally secreted extracellular vesicle, yields therapeutic effects for a variety of diseases, including viral infection. Exosomes and viruses utilize similar endosomal sorting pathways and mechanisms, providing exosomes with the potential to serve as a therapeutic that can target, bind, and suppress cellular uptake of various viruses including the novel severe acute respiratory syndrome coronavirus 2. Here, we review the relationship between exosomes and respiratory viruses, describe potential exosome therapeutics for viral infections, and summarize progress toward clinical translation for lung-derived exosome therapeutics.

Extracellular vesicle-derived miRNA as a novel regulatory system for bi-directional communication in gut-brain-microbiota axis

The gut-brain-microbiota axis (GBMAx) coordinates bidirectional communication between the gut and brain, and is increasingly recognized as playing a central role in physiology and disease. MicroRNAs are important intracellular components secreted by extracellular vesicles (EVs), which act as vital mediators of intercellular and interspecies communication. This review will present current advances in EV-derived microRNAs and their potential functional link with GBMAx. We propose that EV-derived microRNAs comprise a novel regulatory system for GBMAx, and a potential novel therapeutic target for modifying GBMAx in clinical therapy.

Interplay between host non-coding RNAs and influenza viruses

Influenza virus infection through seasonal epidemics and occasional pandemics has been a major public health concern for decades. Incomplete protection from vaccination and increased antiviral resistance due to frequent mutations of influenza viruses have led to a continuous need for new therapeutic options. The functional significance of host protein and influenza virus interactions has been established, but relatively less is known about the interaction of host noncoding RNAs, including microRNAs and long noncoding RNAs, with influenza viruses. In this review, we summarize host noncoding RNA profiles during influenza virus infection and the regulation of influenza virus infection by host noncoding RNAs. Influenza viral non-coding RNAs are briefly discussed. Increased understanding of the molecular regulation of influenza viral replication will be beneficial in identifying potential therapeutic targets against the influenza virus.

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.

Critical role of microRNAs in host and influenza A (H1N1) virus interactions

As a type of non-coding RNA, microRNAs are considered to be a new regulator in viral infections. Influenza A (H1N1) virus infection is a serious threat to human health. There is growing evidence supporting that microRNAs play important roles in various cellular infection stages and host antiviral response during H1N1 infection. Some microRNAs defend against H1N1 invasion, while others may promote viral replication. MicroRNAs are implicated in the host-viral interactions and serve versatile functions in it. In this review, we focus on the innate immune response and virus replication regulated by microRNAs during H1N1 infection. MicroRNAs can influence H1N1 virus replication by directly binding to viral compositions and through host cellular pathways. Moreover, microRNAs are involved in multiple antiviral response, including production of interferons (IFNs), retinoic acid-inducible gene I (RIG-I) signaling pathway, immune cells development and secretion, activation of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB). Furthermore, these regulatory effects of microRNAs suggest its potential clinical significance. In addition, another non-coding RNA, lncRNA, are also mentioned in the review, which can regulate innate immune response and influence virus replication during H1N1 infection as well.

Extracellular Vesicles in Viral Pathogenesis: A Case of Dr. Jekyll and Mr. Hyde

Secretion of extracellular vesicles (EVs) is a fundamental property of living cells. EVs are known to transfer biological signals between cells and thus regulate the functional state of recipient cells. Such vesicles mediate the intercellular transport of many biologically active molecules (proteins, nucleic acids, specific lipids) and participate in regulation of key physiological processes. In addition, EVs are involved in the pathogenesis of multiple diseases: infectious, neurodegenerative, and oncological. The current EV classification into microvesicles, apoptotic bodies, and exosomes is based on their size, pathways of cellular biogenesis, and molecular composition. This review is focused on analysis of the role of EVs (mainly exosomes) in the pathogenesis of viral infection. We briefly characterize the biogenesis and molecular composition of various EV types. Then, we consider EV-mediated pro- and anti-viral mechanisms. EV secretion by infected cells can be an important factor of virus spread in target cell populations, or a protective factor limiting viral invasion. The data discussed in this review, on the effect of EV secretion by infected cells on processes in neighboring cells and on immune cells, are of high significance in the search for new therapeutic approaches and for design of new generations of vaccines.

Respiratory Epithelial Cells Respond to Lactobacillus plantarum but Provide No Cross-Protection against Virus-Induced Inflammation

Virus-induced inflammation plays a critical role in determining the clinical outcome of an acute respiratory virus infection. We have shown previously that the administration of immunobiotic Lactobacillus plantarum (Lp) directly to the respiratory tract prevents lethal inflammatory responses to subsequent infection with a mouse respiratory virus pathogen. While Lp-mediated protective responses involve non-redundant contributions of both Toll-like receptor 2 (TLR2) and NOD2, the cellular basis of these findings remains unclear. Here, we address the impact of Lp and its capacity to suppress inflammation in virus-infected respiratory epithelial cells in two cell culture models. We found that both MLE-12 cells and polarized mouse tracheal epithelial cells (mTECs) were susceptible to infection with Influenza A and released proinflammatory cytokines, including CCL2, CCL5, CXCL1, and CXCL10, in response to replicating virus. MLE-12 cells express NOD2 (81 ± 6.3%) and TLR2 (19 ± 4%), respond to Lp, and are TLR2-specific, but not NOD2-specific, biochemical agonists. By contrast, we found that mTECs express NOD2 (81 ± 17%) but minimal TLR2 (0.93 ± 0.58%); nonetheless, mTECs respond to Lp and the TLR2 agonist, Pam2CSK4, but not NOD2 agonists or the bifunctional TLR2-NOD2 agonist, CL-429. Although MLE-12 cells and mTECS were both activated by Lp, little to no cytokine suppression was observed in response to Lp followed by virus infection via a protocol that replicated experimental conditions that were effective in vivo. Further study and a more complex approach may be required to reveal critical factors that suppress virus-induced inflammatory responses.

Extracellular Vesicles in Viral Infections: Two Sides of the Same Coin?

Extracellular vesicles are small membrane structures containing proteins and nucleic acids that are gaining a lot of attention lately. They are produced by most cells and can be detected in several body fluids, having a huge potential in therapeutic and diagnostic approaches. EVs produced by infected cells usually have a molecular signature that is very distinct from healthy cells. For intracellular pathogens like viruses, EVs can have an even more complex function, since the viral biogenesis pathway can overlap with EV pathways in several ways, generating a continuum of particles, like naked virions, EVs containing infective viral genomes and quasi-enveloped viruses, besides the classical complete viral particles that are secreted to the extracellular space. Those particles can act in recipient cells in different ways. Besides being directly infective, they also can prime neighbor cells rendering them more susceptible to infection, block antiviral responses and deliver isolated viral molecules. On the other hand, they can trigger antiviral responses and cytokine secretion even in uninfected cells near the infection site, helping to fight the infection and protect other cells from the virus. This protective response can also backfire, when a massive inflammation facilitated by those EVs can be responsible for bad clinical outcomes. EVs can help or harm the antiviral response, and sometimes both mechanisms are observed in infections by the same virus. Since those pathways are intrinsically interlinked, understand the role of EVs during viral infections is crucial to comprehend viral mechanisms and respond better to emerging viral diseases.

Altered exosomal microRNA profiles in bronchoalveolar lavage fluid can mediate metabolism in patients with Acinetobacter baumannii ventilator-associated pneumonia

Background

Ventilator-associated pneumonia (VAP) is a major public health problem and is most commonly caused by Acinetobacter baumannii (Ab) infection. In our study, we investigated the profiles of exosomal microRNAs (miRNAs) extracted from the bronchoalveolar lavage fluid (BALF) and serum of patients with Acinetobacter baumannii ventilator-associated pneumonia (Ab-VAP). We also examined the serum metabolomic profiles of these patients. Our aim was to study the associations between lung tissue-derived exosomal miRNAs and changes in global metabolism in patients with Ab-VAP.

Methods

Consecutively sampled patients admitted to an intensive care unit (ICU) for pulmonary infection treatment were enrolled in this study. Demographic information and biochemical measurements were collected. Serum samples were obtained following overnight fasting on admission. Bronchoscopies were performed and BALF samples were collected from each patient. Exosomes were extracted using kits from System Biosciences (SBI) and miRNA sequencing was performed. Non-targeted metabolomics were used to express metabolic profiles.

Results

We found significant changes in the miRNA profiles of patients with Ab-VAP; these changes occurred in both BALF exosomal miRNA and serum exosomal miRNA. Gene Ontology analysis further identified the function of miRNA in system metabolism. Serum metabolomic profiles and ratios of biological significance were found to be differentially regulated in Ab-VAP patients. This differential regulation was correlated with the differential expression of miRNAs.

Conclusions

Our data summarizes the dysregulation of serum metabolism and exosomal miRNA excretion that occurs in Ab-VAP patients. The correlation found between BALF exosomal miRNA and dysregulated metabolism, as indicated by the irregular expression of metabolites in the cellular metabolic pathway, highlights potential biomarkers for the diagnosis and treatment of Ab infection.

miR-29a is a negative regulator of influenza virus infection through targeting of the frizzled 5 receptor

Influenza A virus (IAV) infections result in a large number of deaths and substantial economic losses each year. MicroRNAs repress gene expression and are involved in virus-host interactions. miR-29a is known to have anti-tumor and anti-fibrotic effects. However, the role of miR-29a in IAV infection is unclear. In the present study, we investigated the effect of miR-29a on IAV infection and the mechanisms by which it functions. IAV infection was found to cause decreased miR-29a expression in lung epithelial A549 cells and mouse lungs. Overexpression of miR-29a reduced IAV mRNA and protein levels and progeny virus production in HEK293 and A549 cells. Inhibition of IAV infection by miR-29a was observed with different strains of IAV, including A/PR/8/34, A/WSN/1933, and clinical isolates A/OK/3052/09 and A/OK/309/06 H3N2. Knockout of miR-29a using CRISPR/Cas9 resulted in an increase in viral mRNA and protein levels, confirming that miR-29a suppresses IAV infection. A 3' untranslated region (3'-UTR) reporter assay showed that miR-29a had binding sites in the 3'-UTR of the Wnt-Ca²⁺ signaling receptor frizzled 5 gene, and overexpression of miR-29a reduced the level of the endogenous frizzled 5 protein. Wnt5a treatment of HEK293 and A549 cells enhanced IAV infection. Our results suggest that miR-29a inhibits IAV infection, probably via the frizzled 5 receptor.

Exosomes transfer miRNAs from cell-to-cell to inhibit autophagy during infection with Crohn's disease-associated adherent-invasive E. coli

Adherent-invasive E. coli (AIEC), which abnormally colonize the intestinal mucosa of Crohn's disease (CD) patients, are able to adhere to and invade intestinal epithelial cells (IECs), survive and replicate within macrophages and induce a pro-inflammatory response. AIEC infection of IECs induces secretion of exosomes that increase AIEC replication in exosome-receiving IECs and macrophages. Here, we investigated the mechanism underlying the increased AIEC replication in cells receiving exosomes from AIEC-infected cells. Exosomes released by uninfected human intestinal epithelial T84 cells (Exo-uninfected) or by T84 cells infected with the clinical AIEC LF82 strain (Exo-LF82), the nonpathogenic E. coli K12 strain (Exo-K12) or the commensal E. coli HS strain (Exo-HS) were purified and used to stimulate T84 cells. Stimulation of T84 cells with Exo-LF82 inhibited autophagy compared with Exo-uninfected, Exo-K12 and Exo-HS. qRT-PCR analysis revealed increased levels of miR-30c and miR-130a in Exo-LF82 compared to Exo-uninfected, Exo-K12 and Exo-HS. These miRNAs were transferred via exosomes to recipient cells, in which they targeted and inhibited ATG5 and ATG16L1 expression and thereby autophagy response, thus favoring AIEC intracellular replication. Inhibition of these miRNAs in exosome-donor cells infected with AIEC LF82 abolished the increase in miR-30c and miR-130a levels in the released Exo-LF82 and in Exo-LF82-receiving cells, thus suppressing the inhibitory effect of Exo-LF82 on ATG5 and ATG16L1 expression and on autophagy-mediated AIEC clearance in Exo-LF82-receiving cells. Our study shows that upon AIEC infection, IECs secrete exosomes that can transfer specific miRNAs to recipient IECs, inhibiting autophagy-mediated clearance of intracellular AIEC.

Extracellular vesicles in virus infection and pathogenesis

Viruses are obligate intracellular parasites that usurp cellular signaling networks to promote pathogen spread and disease progression. Signaling through extracellular vesicles (EVs) is an emerging field of study in the virus-host interaction network. EVs relay information both locally and distally through incorporated contents, typically without tripping innate immune sensors. Therefore, this extracellular signaling axis presents itself as a tantalizing target for promoting a favorable niche for the pathogen(s) takeover of the host, particularly for chronic infections. From the incorporation of virus-encoded molecules such as micro RNAs and proteins/enzymes to the envelopment of entire infectious particles, evolutionary distinct viruses have shown a remarkable ability to converge on this means of communication. In this review, we will cover the recent advances in this field and explore how EV can be used as potential biomarkers for chronic, persistent, or latent virus infections.

miR-1975 serves as an indicator of clinical severity upon influenza infection

Emerging evidence highlights the role of non-coding small RNAs in host-influenza interaction. We have identified a Y RNA-derived small RNA, miR-1975, which is upregulated upon influenza A virus infection in A549 cells. The aim of this study is to investigate whether miR-1975 serves as an indicator of clinical severity upon influenza infection. We investigate the abundance of miR-1975 in sera from clinical patients and its correlation with hypoxemia status. We quantified its amounts in sera from influenza virus-infected patients and healthy volunteers by means of stem-loop RT-PCR. Median values of miR-1975 were significantly higher in influenza virus-infected patients, especially in hypoxemic patients. miR-1975 levels at the acute stage of the disease were highly correlated with the fraction of inspired oxygen used by the patients and total ventilator days. Receiver operator characteristic curve analysis revealed that miR-1975 levels in combination with days of fever before presenting to hospital had significant predictive value for hypoxemia and respiratory failure for patients infected with influenza virus. Our results reveal that circulating miR-1975 has great potential to serve as a biomarker for predicting prognosis in patients infected with influenza virus.

Alveolar macrophage-derived extracellular vesicles inhibit endosomal fusion of influenza virus

Alveolar macrophages (AMs) and epithelial cells (ECs) are the lone resident lung cells positioned to respond to pathogens at early stages of infection. Extracellular vesicles (EVs) are important vectors of paracrine signaling implicated in a range of (patho)physiologic contexts. Here we demonstrate that AMs, but not ECs, constitutively secrete paracrine activity localized to EVs which inhibits influenza infection of ECs in vitro and in vivo. AMs exposed to cigarette smoke extract lost the inhibitory activity of their secreted EVs. Influenza strains varied in their susceptibility to inhibition by AM-EVs. Only those exhibiting early endosomal escape and high pH of fusion were inhibited via a reduction in endosomal pH. By contrast, strains exhibiting later endosomal escape and lower fusion pH proved resistant to inhibition. These results extend our understanding of how resident AMs participate in host defense and have broader implications in the defense and treatment of pathogens internalized within endosomes.

Extracellular Vesicles in Viral Replication and Pathogenesis and Their Potential Role in Therapeutic Intervention

Extracellular vesicles (EVs) have shown their potential as a carrier of molecular information, and they have been involved in physiological functions and diseases caused by viral infections. Virus-infected cells secrete various lipid-bound vesicles, including endosome pathway-derived exosomes and microvesicles/microparticles that are released from the plasma membrane. They are released via a direct outward budding and fission of plasma membrane blebs into the extracellular space to either facilitate virus propagation or regulate the immune responses. Moreover, EVs generated by virus-infected cells can incorporate virulence factors including viral protein and viral genetic material, and thus can resemble noninfectious viruses. Interactions of EVs with recipient cells have been shown to activate signaling pathways that may contribute to a sustained cellular response towards viral infections. EVs, by utilizing a complex set of cargos, can play a regulatory role in viral infection, both by facilitating and suppressing the infection. EV-based antiviral and antiretroviral drug delivery approaches provide an opportunity for targeted drug delivery. In this review, we summarize the literature on EVs, their associated involvement in transmission in viral infections, and potential therapeutic implications.

Fungal-host interactions: insights into microRNA in response to Paracoccidioides species

BACKGROUND

Paracoccidioides spp. causes paracoccidioidomycosis (PCM), an important and frequent systemic mycosis that occurs in Latin America. The infectious process begins with contact between the fungus and lung cells, and the molecular pattern of this interaction is currently poorly understood. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the gene expression in many biological processes, including in the infections.

OBJECTIVE

This study aimed to analyse the expression of miRNAs in lung cells as response to infection by Paracoccidioides spp.

METHODS

A quantitative real-time polymerase chain reaction (RT-qPCR) based screening was employed to verify differentially expressed miRNAs in human lung cells infected with three different species; Paracoccidioides lutzii, Paracoccidioides americana, and Paracoccidioides brasiliensis. Furthermore, the in silico predictions of target genes and pathways for miRNAs were obtained.

FINDINGS

The results showed that miRNAs identified in the lung cells were different according to the species studied. However, based on the predicted targets, the potential signaling pathways regulated by miRNAs are common and related to adhesion, actin cytoskeleton rearrangement, apoptosis, and immune response mediated by T cells and TGF-β.

MAIN CONCLUSIONS

In summary, this study showed the miRNAs pattern of epithelial cells in response to infection by Paracoccidioides species and the potential role of these molecules in the regulation of key pathogenesis mechanisms of PCM.

Evasion mechanisms of the type I interferons responses by influenza A virus

The type I interferons (IFNs) represent the first line of host defense against influenza virus infection, and the precisely control of the type I IFNs responses is a central event of the immune defense against influenza viral infection. Influenza viruses are one of the leading causes of respiratory tract infections in human and are responsible for seasonal epidemics and occasional pandemics, leading to a serious threat to global human health due to their antigenic variation and interspecies transmission. Although the host cells have evolved sophisticated antiviral mechanisms based on sensing influenza viral products and triggering of signalling cascades resulting in secretion of the type I IFNs (IFN-α/β), influenza viruses have developed many strategies to counteract this mechanism and circumvent the type I IFNs responses, for example, by inducing host shut-off, or by regulating the polyubiquitination of viral and host proteins. This review will summarise the current knowledge of how the host cells recognise influenza viruses to induce the type I IFNs responses and the strategies that influenza viruses exploited to evade the type I IFNs signalling pathways, which will be helpful for the development of antivirals and vaccines.

Role of Extracellular Vesicles in Influenza Virus Infection

Influenza virus infection is a major health care concern associated with significant morbidity and mortality worldwide, and cause annual seasonal epidemics and pandemics at irregular intervals. Recent research has highlighted that viral components can be found on the extracellular vesicles (EVs) released from infected cells, implying a functional relevance of EVs with influenza virus dissemination. Therefore, exploring the role of EVs in influenza virus infection has been attracting significant attention. In this review, we will briefly introduce the biogenesis of EVs, and focus on the role of EVs in influenza virus infection, and then discuss the EVs-based influenza vaccines and the limitations of EVs studies, to further enrich and boost the development of preventative and therapeutic strategies to combat influenza virus.

Exosome-mediated apoptosis pathway during WSSV infection in crustacean mud crab

MicroRNAs are regulatory molecules that can be packaged into exosomes to modulate cellular response of recipients. While the role of exosomes during viral infection is beginning to be appreciated, the involvement of exosomal miRNAs in immunoregulation in invertebrates has not been addressed. Here, we observed that exosomes released from WSSV-injected mud crabs could suppress viral replication by inducing apoptosis of hemocytes. Besides, miR-137 and miR-7847 were found to be less packaged in mud crab exosomes during viral infection, with both miR-137 and miR-7847 shown to negatively regulate apoptosis by targeting the apoptosis-inducing factor (AIF). Our data also revealed that AIF translocated to the nucleus to induce DNA fragmentation, and could competitively bind to HSP70 to disintegrate the HSP70-Bax (Bcl-2-associated X protein) complex, thereby activating the mitochondria apoptosis pathway by freeing Bax. The present finding therefore provides a novel mechanism that underlies the crosstalk between exosomal miRNAs and apoptosis pathway in innate immune response in invertebrates.

As a form of intercellular vesicular transport, exosomes are widely involved in the regulation of a variety of pathological processes in mammals, yet, the role of exosomes during virus infection in crustaceans remains unknown. In the present study, we identified the miRNAs packaged by exosomes that were possibly involved in WSSV infection by mediating hemocytes apoptosis in crustacean mud crab Scylla paramamosain. The results revealed that exosomes released from WSSV-injected mud crabs could suppress viral replication by inducing hemocytes apoptosis. Moreover, it was found that miR-137 and miR-7847 were less packaged in exosomes after WSSV challenge, resulting in the activation of AIF, while AIF could translocate to nucleus to induce DNA fragmentation or disintegrate the HSP70-Bax complex and freeing Bax to mitochondria, which eventually caused apoptosis and suppressed viral infection of the recipient hemocytes. Our finding is the first to reveal the involvement of exosomal miRNAs in antiviral immune response in mud crabs, which shows a novel molecular mechanism of invertebrate resistance to pathogenic microbial infection.

High Levels of miR-483-3p Are Present in Serum Exosomes Upon Infection of Mice With Highly Pathogenic Avian Influenza Virus

Exosomes, the extracellular vesicles that contain functional proteins and RNAs, regulate cell-cell communication. Recently, our group reported that levels of various microRNAs (miRNAs) in bronchoalveolar lavage fluid exosomes were highly increased in influenza virus-infected mice and that one of those miRNAs, miR-483-3p, was involved in the potentiation of the innate immune responses to influenza virus infection in mouse type II pneumocytes. Here, we evaluated exosomal miR-483-3p levels in the serum of influenza virus-infected mice and found that miR-483-3p levels were significantly increased during infection with a highly pathogenic avian H5N1 influenza virus. Moreover, miR-483-3p-enriched exosomes derived from type II pneumocytes potentiated the expression of proinflammatory cytokine genes in vascular endothelial cells. Our findings suggest that serum exosomal transfer of miR-483-3p might be involved in the inflammatory pathogenesis of H5N1 influenza virus infection.

Exosomal miRNAs: novel players in viral infection

Exosomes are secreted nanovesicles that are able to transfer their cargo (such as miRNAs) between cells. To determine to what extent exosomes and exosomal miRNAs are involved in the pathogenesis, progression and diagnosis of viral infections. The scientific literature (PubMed and Google Scholar) was searched from 1970 to 2019. The complex biogenesis of exosomes and miRNAs was reviewed. Exosomes contain both viral and host miRNAs that can be used as diagnostic biomarkers for viral diseases. Viral proteins can alter miRNAs, and conversely miRNAs can alter the host response to viral infections in a positive or negative manner. It is expected that exosomal miRNAs will be increasingly used for diagnosis, monitoring and even treatment of viral infections.

Exosomal miR-103a-3p ameliorates lipopolysaccharide-induced immune response in BEAS-2B cells via NF-κB pathway by targeting transducin β-like 1X related protein 1

Abnormal immune response contributes to pathophysiology of pneumonia and is recognized as a main factor for high incidence rate in children. The association between exosomes and inflammation has been reported in diverse cell types and diseases. The current study focuses on exploring the effects of exosomal miR-103a-3p on lipopolysaccharide (LPS)-induced inflammation, and investigates the underlying mechanisms. We proved that miR-103a-3p was lowly expressed in blood samples of pneumonia patients and LPS-induced lung cells, and overexpression of miR-103a-3p weaken the LPS-induced inflammation. Using luciferase reporter assay and immunoprecipitation assay, we demonstrated that miR-103a-3p directly binds to a specific region of transducin β-like 1X related protein 1 (TBL1XR1), mediating the NF-κB signalling pathway, thus regulating immune response. Taken together, our data revealed that miR-103a-3p functions as an anti-inflammatory gene in childhood pneumonia and can be applied as therapeutic targets for the treatment of childhood pneumonia in the future.

Host microRNAs and exosomes that modulate influenza virus infection

MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate over half of human protein-coding genes and play a vital role in cellular development, proliferation, metabolism, and homeostasis. Exosomes are rounded or cup-like extracellular vesicles that carry proteins, mRNAs, miRNAs, and lipids for release and exchange messages between cells involved in various cellular processes. Influenza virus is a substantial public health challenge. The expression of host miRNAs is altered in response to stimulation by influenza virus. These dysregulated miRNAs directly or indirectly target viral genes to regulate viral replication and stimulate or suppress innate immune responses and cell apoptosis during viral infection. Exosomes released by infected cells are associated with the transfer of antigens and key molecules that activate and modulate immune function. Dysregulation of miRNAs and secretion of exosomes are associated with pathogenicity and immune regulation during influenza infection. This review provides a comprehensive summary of the information available regarding host miRNAs and exosomes that are involved in the modulation of influenza virus infection and will facilitate the development of preventative or therapeutic strategies against influenza virus.

Web of interferon stimulated antiviral factors to control the influenza A viruses replication

Influenza viruses cause mild to severe infections in animals and humans worldwide with significant morbidity and mortality. Infection of eukaryotic cells with influenza A viruses triggers the induction of innate immune system through the interaction between pattern recognition receptors (PRRs) and pathogen associated molecular patterns (PAMPs), which culminate in the induction of interferons (IFNs). Consequently, IFNs bind to their cognate receptors on the cellular membrane and activate the signaling pathway for transcriptional regulation of interferon-stimulated genes (ISGs) through Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway. Cumulative actions of these ISGs establish an antiviral state of the host. Several ISGs have been described, which play critical roles to inhibit the infection and replication of influenza A viruses at multiple steps of virus life cycle. In this review, the dynamics and redundancy of these ISGs against influenza A viruses are discussed. Additionally, current understanding and molecular mechanisms that are underlying the roles of ISGs in pathogenesis of influenza virus are critically reviewed.

Lung-derived exosomes in phosgene-induced acute lung injury regulate the functions of mesenchymal stem cells partially via miR-28-5p

Accidental phosgene exposure can result in acute lung injury (ALI). Mesenchymal stem cells (MSCs) have been found to alleviate phosgene-induced ALI. However, the mechanism of MSCs underlying such protective effect remains largely unexplored. Exosomes, important components of microenvironment, are closely associated with intercellular information transfer. In the present study, we isolated lung exosomes in rats after phosgene exposure by ultracentrifugation and explored their effects on MSCs in vitro. ALI exosomes were elliptical in shape and 50-200 nm in size. ALI exosomes could promote proliferation and migration of MSCs. Moreover, ALI exosomes increased the secretion of IL-10, leading to enhanced immunoregulatory properties of MSCs. The paracrine factors, VEGF, HGF, LL-37 and Ang-1, were also augmented by ALI exosomes. However, ALI exosomes had no effect on differentiation of MSCs towards lung alveolar cells. To identify the effective miRNAs in ALI exosomes, we performed miRNA profile analysis. MiR-28-5p was considered as a possible effective molecule. We further studied the effect of miR-28-5p on MSCs. MiR-28-5p mimic promoted proliferation, migration, immunomodulation of MSCs. MiR-28-5p mimic promoted the paracrine of VEGF, HGF, LL-37 and Ang-1. Besides, we explored molecular mechanism of miR-28-5p in MSCs. PI3K/Akt signaling pathway was found significantly augmented by miR-28-5p mimic, indicating the activation in this process. Taken together, our findings could help identify the effects of lung-derived exosomes on MSCs, and the effective molecule in exosomes, miR-28-5p, activated MSCs through PI3K/Akt signaling pathway.

Exosome-delivered and Y RNA-derived small RNA suppresses influenza virus replication

Background

Multiple interplays between viral and host factors are involved in influenza virus replication and pathogenesis. Several small RNAs have recently emerged as important regulators of host response to viral infections. The aim of this study was to characterize the functional role of hsa-miR-1975, a Y5 RNA-derived small RNA, in defending influenza virus and delineate the mechanisms.

Methods

We performed high throughput sequencing of small RNAs in influenza virus-infected cells to identify up- or down- regulated small RNA species. The expression of the most abundant RNA species (hsa-miR-1975) was validated by stem-loop reverse transcription-polymerase chain reaction (RT-PCR). Antiviral effects of hsa-miR-1975 were confirmed by Western Blot, RT-PCR and plaque assay. In vitro perturbation of hsa-miR-1975 combined with exosomes isolation was used to elucidate the role and mechanism of hsa-miR-1975 in the context of antiviral immunity.

Results

Small RNA sequencing revealed that hsa-miR-1975 was the most up-regulated small RNA in influenza virus-infected cells. The amount of intracellular hsa-miR-1975 increased in the late stage of the influenza virus replication cycle. The increased hsa-miR-1975 was at least partially derived from degradation of Y5RNA as a result of cellular apoptosis. Unexpectedly, hsa-miR-1975 mimics inhibited influenza virus replication while hsa-miR-1975 sponges enhanced the virus replication. Moreover, hsa-miR-1975 was secreted in exosomes and taken up by the neighboring cells to induce interferon expression.

Conclusions

Our findings unravel a critical role of Y-class small RNA in host’s defense against influenza virus infection and reveal its antiviral mechanism through exosome delivery. This may provide a new candidate for targeting influenza virus.

Electronic supplementary material

The online version of this article (10.1186/s12929-019-0553-6) contains supplementary material, which is available to authorized users.

Extracellular RNA in viral-host interactions: Thinking outside the cell

Small RNAs and their associated RNA interference (RNAi) pathways underpin diverse mechanisms of gene regulation and genome defense across all three kingdoms of life and are integral to virus-host interactions. In plants, fungi and many animals, an ancestral RNAi pathway exists as a host defense mechanism whereby viral double-stranded RNA is processed to small RNAs that enable recognition and degradation of the virus. While this antiviral RNAi pathway is not generally thought to be present in mammals, other RNAi mechanisms can influence infection through both viral- and host-derived small RNAs. Furthermore, a burgeoning body of data suggests that small RNAs in mammals can function in a non-cell autonomous manner to play various roles in cell-to-cell communication and disease through their transport in extracellular vesicles. While vesicular small RNAs have not been proposed as an antiviral defense pathway per se, there is increasing evidence that the export of host- or viral-derived RNAs from infected cells can influence various aspects of the infection process. This review discusses the current knowledge of extracellular RNA functions in viral infection and the technical challenges surrounding this field of research. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA in Disease and Development > RNA in Disease Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.