Exosome Biogenesis and Biological Function in Response to Viral Infections

Exosomal circ_CCDC7/gga-miR-6568-3p/Pax7 axis accelerates the differentiation of chicken embryonic stem cells infected with subgroup J avian leukosis virus

Exosome-mediated horizontal and vertical transmission of subgroup J avian leukosis virus (ALV-J) in poultry flocks can lead to growth inhibition and severe immunosuppression. However, there are few reports on the early infection of chicken embryonic stem cells (cESCs) with ALV-J. In this study, we confirmed that early infection with ALV-J can accelerate the differentiation of cESCs and promote the secretion of exosomes. To investigate the modulation strategy of ALV-J in cESCs, circRNA sequencing was performed for further analysis. A total of 305 differentially expressed circRNAs (DECs) were obtained, including 71 upregulated DECs. Circ-CCDC7 was found to be the most upregulated DEC and was assessed by qRT-PCR, with the result consistent with the result of circRNA-seq. Based on qRT-PCR, gga-miR-6568-3p was found to be the target of the top 3 DECs, including circ-CCDC7, and the stem cell marker gene Pax7 was identified as the target gene of gga-miR-6568-3p. This study demonstrated that exosomal circ-CCDC7/gga-miR-6568-3p/Pax7 accelerates the differentiation of cESCs after early infection with ALV-J.

Comprehensive proteomic analysis of HCoV-OC43 virions and virus-modulated extracellular vesicles

Viruses are obligate parasites that depend on the cellular machinery for their propagation. Several viruses also incorporate cellular proteins that facilitate viral spread. Defining these cellular proteins is critical to decipher viral life cycles and delineate novel therapeutic strategies. While numerous studies have explored the importance of host proteins in coronavirus spread, information about their presence in mature virions is limited. In this study, we developed a protocol to highly enrich mature HCoV-OC43 virions and characterize them by proteomics. Recognizing that cells release extracellular vesicles whose content is modulated by viruses, and given our ability to separate virions from these vesicles, we also analyzed their protein content in both uninfected and infected cells. We uncovered 69 unique cellular proteins associated with virions including 31 high-confidence hits. These proteins primarily regulate RNA metabolism, enzymatic activities, vesicular transport, cell adhesion, metabolite interconversion, and translation. We further discovered that the virus had a profound impact on exosome composition, incorporating 47 novel cellular proteins (11 high confidence) and excluding 92 others (61 high confidence) in virus-associated extracellular vesicles compared to uninfected cells. Moreover, a dsiRNA screen revealed that 11 of 18 select targets significantly impacted viral yields, including proteins found in virions or extracellular vesicles. Overall, this study provides new and important insights into the incorporation of numerous host proteins into HCoV-OC43 virions, their biological significance, and the ability of the virus to modulate extracellular vesicles.

IMPORTANCE

In recent years, coronaviruses have dominated global attention, making it crucial to develop methods to control them and prevent future pandemics. Besides viral proteins, host proteins play a significant role in viral propagation and offer potential therapeutic targets. Targeting host proteins is advantageous because they are less likely to mutate and develop resistance compared to viral proteins, a common issue with many antiviral treatments. In this study, we examined the protein content of the less virulent biosafety level 2 HCoV-OC43 virus as a stand-in for the more virulent SARS-CoV-2. Our findings reveal that several cellular proteins incorporated into the virion regulate viral spread. In addition, we report that the virus extensively modulates the content of extracellular vesicles, enhancing viral dissemination. This underscores the critical interplay between the virus, host proteins, and extracellular vesicles.

Exosomal miR-7-25207 Increases Subgroup J Avian Leukosis Virus Titers by Targeting the Akt-CyclinQ1 and PRC1-YAF2 Dual Pathways

Subgroup J avian leukosis virus (ALV-J) is a major pathogen in poultry, causing substantial economic losses to the poultry industry worldwide. Exosomal small RNAs derived from virus-infected cells or biological fluids can serve as viral transmission vectors. However, the role and mechanism of exosomal miRNA in ALV-J infection are unclear. In this study, we demonstrated that exosomal microRNA-7-25207 (miR-7-25207) could increase the titers of ALV-J. Exosomes isolated from ALV-J-infected DF-1 cells (Exo-ALV-J) contained partial viral proteins from ALV-J and could transmit the infection to uninfected DF-1 cells, leading to productive infection. Additionally, the RNA expression profile of exosomes was altered following ALV-J infection. miRNA analysis revealed that the expression of exosomal miR-7-25207 increased. Overexpression of miR-7-25207 significantly increased the titers of ALV-J in transfected cells. Furthermore, miR-7-25207 directly suppressed the expression of Akt and PRC1. Akt, in turn, directly inhibited CyclinQ1 expression, while PRC1 directly interfered with YAF2 expression. In conclusion, ALV-J infection activates the expression of miR-7-25207, which is subsequently delivered via exosomes to uninfected cells, increasing ALV-J titers by targeting Akt-CyclinQ1 and PRC1-YAF2 dual pathways. These findings suggest that exosomal miR-7-25207 may serve as a potential biomarker for clinical parameters in ALV-J infection.

Epstein-Barr virus-encoded BART9 and BART15 miRNAs are elevated in exosomes of cerebrospinal fluid from relapsing-remitting multiple sclerosis patients

Epstein-Barr virus (EBV) infection is approved as the main environmental trigger of multiple sclerosis (MS). In this path, we quantified ebv-miR-BART9-3p and ebv-miR-BART15 in exosomes of cerebrospinal fluid (CSF) of untreated relapsing-remitting MS (RRMS) patients in comparison with the control group. Interestingly, patients displayed significant upregulation of ebv-miR-BART9-3p (18.4-fold) and ebv-miR-BART15 (3.1-fold) expression in CSF exosomes. Moreover, the expression levels of hsa-miR-21-5p and hsa-miR-146a-5p were found to be significantly elevated in the CSF samples obtained from the patient group compared to those obtained from the HC group. The levels of Interferon-gamma (IFN-γ), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-17 (IL-17), interleukin-23 (IL-23), transforming growth factor beta (TGF-β), and tumor necrosis factor-alpha (TNF-α) were observed to be significantly elevated in the serum and CSF exosomes of the patients. The highest increase was observed in TGF-β (8.5-fold), followed by IL-23 (3.9-fold) in CSF exosomes. These findings are in agreement with the association between EBV infection and inflammatory cytokines induction. Furthermore, the ratios of TGF-β: TNF-α and TGF-β: IFN-γ attained values of 4 to 16.4 and 1.3 to 3.6, respectively, in the CSF exosomes of the patients, in comparison to those of the control group. These findings show EBV activity in RRMS patients is different from that of healthy ones. Elevation of ebv-miR-BART9-3p, ebv-miR-BART15, and inflammatory cytokines expression in CSF exosomes in RRMS patients provides a substantial link between EBV activity and the onset of the disease, as well as the transition from EBV infection to MS.

Engineered dendritic cells-derived exosomes harboring HIV-1 Nefmut-Tat fusion protein and heat shock protein 70: A promising HIV-1 safe vaccine candidate

Antigen presenting cells (APCs)-derived exosomes are nano-vesicles that can induce antigen-specific T cell responses, and possess therapeutic effects in clinical settings. Moreover, dendritic cells (DCs)-based vaccines have been developed to combat human immunodeficiency virus-1 (HIV-1) infection in preclinical and clinical trials. We investigated the immunostimulatory effects (B- and T-cells activities) of DCs- and exosomes-based vaccine constructs harboring HIV-1 Nefmut-Tat fusion protein as an antigen candidate and heat shock protein 70 (Hsp70) as an adjuvant in mice. The modified DCs and engineered exosomes harboring Nefmut-Tat protein or Hsp70 were prepared using lentiviral vectors compared to electroporation, characterized and evaluated by in vitro and in vivo immunological tests. Our data indicated that the engineered exosomes induced high levels of total IgG, IgG2a, IFN-γ, TNF-α and Granzyme B. Moreover, co-injection of exosomes harboring Hsp70 could significantly increase the secretion of antibodies, cytokines and Granzyme B. The highest levels of IFN-γ and TNF-α were observed in exosomes harboring Nefmut-Tat combined with exosomes harboring Hsp70 (Exo-Nefmut-Tat + Exo-Hsp70) regimen after single-cycle replicable (SCR) HIV-1 exposure. Generally, Exo-Nefmut-Tat + Exo-Hsp70 regimen can be considered as a promising safe vaccine candidate due to high T-cells (Th1 and CTL) activity and its maintenance against SCR HIV-1 exposure.

Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology

Acknowledging the neurological symptoms of COVID-19 and the long-lasting neurological damage even after the epidemic ends are common, necessitating ongoing vigilance. Initial investigations suggest that extracellular vesicles (EVs), which assist in the evasion of the host's immune response and achieve immune evasion in SARS-CoV-2 systemic spreading, contribute to the virus's attack on the central nervous system (CNS). The pro-inflammatory, pro-coagulant, and immunomodulatory properties of EVs contents may directly drive neuroinflammation and cerebral thrombosis in COVID-19. Additionally, EVs have attracted attention as potential candidates for targeted therapy in COVID-19 due to their innate homing properties, low immunogenicity, and ability to cross the blood-brain barrier (BBB) freely. Mesenchymal stromal/stem cell (MSCs) secreted EVs are widely applied and evaluated in patients with COVID-19 for their therapeutic effect, considering the limited antiviral treatment. This review summarizes the involvement of EVs in COVID-19 neuropathology as carriers of SARS-CoV-2 or other pathogenic contents, as predictors of COVID-19 neuropathology by transporting brain-derived substances, and as therapeutic agents by delivering biotherapeutic substances or drugs. Understanding the diverse roles of EVs in the neuropathological aspects of COVID-19 provides a comprehensive framework for developing, treating, and preventing central neuropathology and the severe consequences associated with the disease.

Extracellular Vesicles: A Novel Mode of Viral Propagation Exploited by Enveloped and Non-Enveloped Viruses

Extracellular vesicles (EVs) are small membrane-enclosed structures that have gained much attention from researchers across varying scientific fields in the past few decades. Cells secrete diverse types of EVs into the extracellular milieu which include exosomes, microvesicles, and apoptotic bodies. These EVs play a crucial role in facilitating intracellular communication via the transport of proteins, lipids, DNA, rRNA, and miRNAs. It is well known that a number of viruses hijack several cellular pathways involved in EV biogenesis to aid in their replication, assembly, and egress. On the other hand, EVs can also trigger host antiviral immune responses by carrying immunomodulatory molecules and viral antigens on their surface. Owing to this intricate relationship between EVs and viruses, intriguing studies have identified various EV-mediated viral infections and interrogated how EVs can alter overall viral spread and longevity. This review provides a comprehensive overview on the EV-virus relationship, and details various modes of EV-mediated viral spread in the context of clinically relevant enveloped and non-enveloped viruses.

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.

Human Papillomavirus-Associated Tumor Extracellular Vesicles in HPV+ Tumor Microenvironments

Most infections with human papillomaviruses (HPVs) are self-resolving and asymptomatic. However, some infections can lead to the development of cancer at different mucosal sites, such as the cervix and the head and neck. Head and neck cancers (HNCs) are dichotomized into HPV-positive (HPV+) or HPV-negative (HPV-) based on their respective etiologies. Notably, the tumor microenvironment (TME) of the HPV+ subtype has an immune landscape characterized with increased immune infiltration, higher levels of T cell activation, and higher levels of immunoregulatory stimuli compared to their HPV- counterparts. Both enveloped and nonenveloped viruses hijack the extracellular vesicle (EV) biogenesis pathway to deploy a "trojan horse" strategy with a pseudoviral envelope to enhance infectivity and evade inflammation. EVs derived from HPV-infected tumor cells could allow for the stealth transport of viral cargo to neighboring nonmalignant cellular populations or infiltrating immune cells within the TME. Furthermore, viral cargo or altered cellular cargo from HPV-associated tumor EVs (HPV-TEVs) could alter the functional state or biological responses of the recipient cellular populations, which could shape the distinctive HPV+ TME. This review will cover the impact of EVs released from HPV-infected cells on HPV-induced carcinogenesis, their role in shaping the distinctive HPV+ tumor microenvironment, and current efforts to develop a painless EV-based liquid biopsy for HPV+ cancers.

Advances in Therapeutic Applications of Extracellular Vesicles

Extracellular vesicles (EVs) are nanoscale bilayer phospholipid membrane vesicles released by cells. Contained large molecules such as nucleic acid, protein, and lipid, EVs are an integral part of cell communication. The contents of EVs vary based on the cell source and play an important role in both pathological and physiological conditions. EVs can be used as drugs or targets in disease treatment, and changes in the contents of EVs can indicate the progression of diseases. In recent years, with the continuous exploration of the structure, characteristics, and functions of EVs, the potential of engineered EVs for drug delivery and therapy being constantly explored. This review provides a brief overview of the structure, characteristics and functions of EVs, summarizes the advanced application of EVs and outlook on the prospect of it. It is our hope that this review will increase understanding of the current development of medical applications of EVs and help us overcome future challenges.

Selective pharmacological inhibition alters human carcinoma lung cell-derived extracellular vesicle formation

Exosomes also termed small extracellular vesicles (sEVs) are important mediators of intercellular communication in many physiological and pathological processes such as protein clearance, immunity, infections, signaling, and cancer. Elevated circulating levels of exosomes have been linked to some viral infections, aggressive cancer, and neurodegenerative diseases. Some pharmacological compounds have been demonstrated to effectively inhibit exosome production pathways. There are very few studies on exosome inhibition and how they influence pathophysiological conditions.

Methods

In the current study, we examined how inhibition of extracellular vesicle release and/or uptake would impact the exosome formation pathway. Using a constellation of improved EV experimental approaches, we evaluated the concentration-based cytotoxicity effects of pharmacological agents (ketoconazole, climbazole, and heparin) on Human Lung Carcinoma (A549) cell viability. We investigated the effect of inhibitor dosages on exosome production and release. Analysis of exosome inhibition includes quantitative analysis and total protein expression of exosome release after pharmacological inhibition; we examined exosome protein level after inhibition.

Results

Selective inhibition of exosomes altered particle sizes, and heparin significantly reduced the total exosomes released. Climbazole and heparin undermined membrane-bound tetraspanin CD63 expression and significantly disrupted ALIX protein (p ≤ 0.0001) and TSG101 (p ≤ 0.001). Azoles and heparin also disrupt transmembrane trafficking by modulating Ras binding protein (p ≤ 0.001).

Conclusion

These findings revealed that pharmacological inhibition of exosomes regulates the endocytic pathway and expression of endosomal sorting complex required for transport mediators, suggesting climbazole and heparin as effective inhibitors of exosome synthesis.

Novel Technologies for Exosome and Exosome-like Nanovesicle Procurement and Enhancement

Exosomes are extracellular nanovesicles commonly produced by mammalian cells that in recent years have risen as a novel strategy for drug delivery systems and cancer therapy because of their innate specificity and high bioavailability. However, there are limitations that undermine their potential. Among them is the lack of mass production capacity with the current available sources and the failure to reach the intended therapeutic effect because of their insufficient uptake or their rapid clearance once administered. This review aims to show the current advances in overcoming these limitations by presenting, firstly, reported strategies to improve exosome and exosome-like nanovesicle extraction from possible novel eukaryotic sources, including animals, plants, and protozoa; and secondly, alternative modification methods that functionalize exosomes by conferring them higher targeting capacity and protection from organism defenses, which results in an increase in the attachment of ligands and cellular uptake of inorganic materials. However, even when these strategies might address some of the obstacles in their procurement and therapeutic use, there are still several aspects that need to be addressed, so several perspectives of the matter are also presented and analyzed throughout this work.

Dendritic cell-derived exosomes: A new horizon in personalized cancer immunotherapy?

Dendritic cells (DCs) release nanometer-sized membrane vesicles known as dexosomes, containing different molecules, particularly proteins, for presenting antigens, i.e., major histocompatibility complex (MHC)-I/II and CD86. Dexosomes can, directly and indirectly, stimulate antigen-reactive CD8⁺ and CD4⁺ T cell responses. Antigen-loaded dexosomes can lead to the development of potent anti-tumoral immune responses. Notably, developing dexosome-based cell-free vaccines could serve as a new vaccination platform in the era of immunotherapy for various cancers. Furthermore, combining dexosomes vaccination strategies with other treatment approaches can considerably increase tumor-specific T cell responses. Herein, we aimed to review how dexosomes interact with immune cells, e.g., CD4⁺ and CD8⁺ T cells and natural killer (NK) cells. Besides, we discussed the limitations of this approach and suggested potential strategies to improve its effectiveness for affected patients.

Stem cell-derived exosomes in bone healing: focusing on their role in angiogenesis

Fractures in bone, a tissue critical in protecting other organs, affect patients' quality of life and have a heavy economic burden on societies. Based on regenerative medicine and bone tissue engineering approaches, stem cells have become a promising and attractive strategy for repairing bone fractures via differentiation into bone-forming cells and production of favorable mediators. Recent evidence suggests that stem cell-derived exosomes could mediate the therapeutic effects of their counterpart cells and provide a cell-free therapeutic strategy in bone repair. Since bone is a highly vascularized tissue, coupling angiogenesis and osteogenesis is critical in bone fracture healing; thus, developing therapeutic strategies to promote angiogenesis will facilitate bone regeneration and healing. To this end, stem cell-derived exosomes with angiogenic potency have been developed to improve fracture healing. This review summarizes the effects of stem cell-derived exosomes on the repair of bone tissue, focusing on the angiogenesis process.

Canine Coronavirus Infection Modulates the Biogenesis and Composition of Cell-Derived Extracellular Vesicles

Coronavirus (CoV) has persistently become a global health concern causing various diseases in a wide variety of hosts, including humans, birds, and companion animals. However, the virus-mediated responses in animal hosts have not been studied extensively due to pathogenesis complexity and disease developments. Extracellular vesicles (EVs) are widely explored in viral infections for their intercellular communication, nanocarrier, and immunomodulatory properties. We proposed that coronavirus hijacks the host exosomal pathway and modulates the EV biogenesis, composition, and protein trafficking in the host. In the present study, Crandell-Rees feline kidney (CRFK) cells were infected with canine coronavirus (CCoV) in an exosome-free medium at the multiplicity of infection (MOI) of 400 infectious units (IFU) at various time points. The cell viability was significantly decreased over time, as determined by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Post-infection EVs were isolated, and transmission electron microscopy (TEM) showed the presence of small EVs (sEVs) after infection. NanoSight particle tracking analysis (NTA) revealed that EV sizes averaged between 100 and 200 nm at both incubation times; however, the mean size of infection-derived EVs was significantly decreased at 48 h when compared to uninfected control EVs. Quantitative analysis of protein levels performed by dot blot scanning showed that the expression levels of ACE-2, annexin-V, flotillin-1, TLR-7, LAMP, TNF-α, caspase-1, caspase-8, and others were altered in EVs after infection. Our findings suggested that coronavirus infection impacts cell viability, modulates EV biogenesis, and alters cargo composition and protein trafficking in the host, which could impact viral progression and disease development. Future experiments with different animal CoVs will provide a detailed understanding of host EV biology in infection pathogenesis and progression. Hence, EVs could offer a diagnostic and therapeutic tool to study virus-mediated host responses that could be extended to study the interspecies jump of animal CoVs to cause infection in humans.

Extracellular vesicles from Zika virus-infected cells display viral E protein that binds ZIKV-neutralizing antibodies to prevent infection enhancement

Mosquito-borne flaviviruses including Zika virus (ZIKV) represent a public health problem in some parts of the world. Although ZIKV infection is predominantly asymptomatic or associated with mild symptoms, it can lead to neurological complications. ZIKV infection can also cause antibody-dependent enhancement (ADE) of infection with similar viruses, warranting further studies of virion assembly and the function of envelope (E) protein-specific antibodies. Although extracellular vesicles (EVs) from flavivirus-infected cells have been reported to transmit infection, this interpretation is challenged by difficulties in separating EVs from flavivirions due to their similar biochemical composition and biophysical properties. In the present study, a rigorous EV-virion separation method combining sequential ultracentrifugation and affinity capture was developed to study EVs from ZIKV-infected cells. We find that these EVs do not transmit infection, but EVs display abundant E proteins which have an antigenic landscape similar to that of virions carrying E. ZIKV E-coated EVs attenuate antibody-dependent enhancement mediated by ZIKV E-specific and DENV-cross-reactive antibodies in both cell culture and mouse models. We thus report an alternative route for Flavivirus E protein secretion. These results suggest that modulation of E protein release via virions and EVs may present a new approach to regulating flavivirus-host interactions.

Proteomic profiling of urinary small extracellular vesicles in children with pneumonia: a pilot study

BACKGROUND

Small extracellular vesicles (sEV) play a crucial role in immune responses to viral infection. However, the composition of sEV derived from children with viral pneumonia remains ill defined.

METHODS

First, we performed mass spectrometry-based label-free proteomic analysis of urinary sEV in 7 children with viral pneumonia, 4 children with Mycoplasma pneumoniae pneumonia and 20 healthy children. Then a total of 33 proteins were selected to validate by multiple reaction monitoring analysis in an independent cohort of 20 healthy children and 29 children with pneumonia.

RESULTS

In the discovery phase, a total of 1621 proteins were identified, while 260 proteins have differential expression in children with viral pneumonia compared to healthy children. Biological pathways primarily associated with neutrophil degranulation, carbohydrate metabolism and endocytosis were enriched in children with viral pneumonia. Finally, the abundance of eight proteins was verified to be significantly higher in children with viral pneumonia than in healthy children.

CONCLUSIONS

This pilot study with proteomic profiles of urinary sEV provided insights to the host response to viral pathogen exposure and potential diagnostic biomarkers for children with viral pneumonia, and served as the basis for understanding the fundamental biology of infection.

IMPACT

There were significant differences in the proteomic features of urinary sEV between children with viral pneumonia and those with Mycoplasma pneumoniae pneumonia. Many viral infection-related proteins were identified in urinary sEV and overrepresented in children with viral pneumonia, which facilitates our understanding of the fundamental biology of viral infection. A total of eight proteins (ANPEP, ASAH1, COL11A1, EHD4, HEXB, LGALS3BP, SERPINA1 and SERPING1) were verified as potential biomarkers for the diagnosis of viral pneumonia in children.

Exosomes mediate Coxsackievirus B3 transmission and expand the viral tropism

Specific virus-receptor interactions are important determinants in viral host range, tropism and pathogenesis, influencing the location and initiation of primary infection as well as viral spread to other target organs/tissues in the postviremic phase. Coxsackieviruses of Group B (CVB) and its six serotypes (CVB1-6) specifically interact with two receptor proteins, coxsackievirus-adenovirus receptor (CAR) and decay-accelerating factor (DAF), and cause various lesions in most permissive tissues. However, our previous data and other studies revealed that virus receptor-negative cells or tissues can be infected with CVB type 3 (CVB3), which can also effectively replicate. To study this interesting finding, we explored the possibility that exosomes are involved in CVB3 tropism and that exosomes functionally enhance CVB3 transmission. We found that exosomes carried and delivered CVB3 virions, resulting in efficient infection in receptor-negative host cells. We also found that delivery of CVB3 virions attached to exosomes depended on the virus receptor CAR. Importantly, exosomes carrying CVB3 virions exhibited greater infection efficiency than free virions because they accessed various entry routes, overcoming restrictions to viral tropism. In vivo experiments demonstrated that inhibition of exosome coupling with virions attenuated CVB3-induced immunological system dysfunction and reduced mortality. Our study describes a new mechanism in which exosomes contribute to viral tropism, spread, and pathogenesis.

Protein-Coding Region Derived Small RNA in Exosomes from Influenza A Virus-Infected Cells

Exosomes may function as multifactorial mediators of cell-to-cell communication, playing crucial roles in both physiological and pathological processes. Exosomes released from virus-infected cells may contain RNA and proteins facilitating infection spread. The purpose of our study was to analyze how the small RNA content of exosomes is affected by infection with the influenza A virus (IAV). Exosomes were isolated by ultracentrifugation after hemadsorption of virions and their small RNA content was identified using high-throughput sequencing. As compared to mock-infected controls, 856 RNA transcripts were significantly differentially expressed in exosomes from IAV-infected cells, including fragments of 458 protein-coding (pcRNA), 336 small, 28 long intergenic non-coding RNA transcripts, and 33 pseudogene transcripts. Upregulated pcRNA species corresponded mainly to proteins associated with translation and antiviral response, and the most upregulated among them were RSAD2, CCDC141 and IFIT2. Downregulated pcRNA species corresponded to proteins associated with the cell cycle and DNA packaging. Analysis of differentially expressed pseudogenes showed that in most cases, an increase in the transcription level of pseudogenes was correlated with an increase in their parental genes. Although the role of exosome RNA in IAV infection remains undefined, the biological processes identified based on the corresponding proteins may indicate the roles of some of its parts in IAV replication.

Exosomal HBV-DNA for diagnosis and treatment monitoring of chronic hepatitis B

This study examined exosomal hepatitis B virus (HBV)-DNA levels in chronic HBV infection (CHB). Patients were grouped according to the European Association for the Study of the Liver classification (1: HBV-DNA-positive CHB, normal alanine aminotransferase [ALT]; 2: HBV-DNA-positive CHB, elevated ALT; 3: HBV-DNA-negative HBeAb-positive CHB, normal ALT; 4: HBV-DNA-positive HBeAg-negative HBeAb-positive CHB, elevated ALT; 5: HBV-DNA-negative, HBcAb-positive; 6: HBV-negative, normal ALT). Exosomes were isolated, comparative analysis of exosomes and serum HBV-DNA. The HBV-DNA content was lower in exosomes than in serum for groups 1, 2, and 4 (all P < 0.05). In the groups negative for serum HBV-DNA (groups 3 and 5), the exosomal HBV-DNA levels were higher than the serum HBV-DNA levels (all P < 0.05). The exosomal and serum HBV-DNA levels were correlated in groups 2 (R ² = 0.84) and 4 (R ² = 0.98). The exosomal HBV-DNA levels were correlated with total bilirubin (R ² = 0.94), direct bilirubin (R ² = 0.82), and indirect bilirubin (R ² = 0.81) in group 5 (all P < 0.05). In patients with CHB and negative for serum HBV-DNA, exosomal HBV-DNA was detectable and could be used to monitor the treatment effects. Exosomal HBV-DNA could be used in patients with a high suspicion of HBV infection but negative for serum HBV-DNA.

Dissecting order amidst chaos of programmed cell deaths: construction of a diagnostic model for KIRC using transcriptomic information in blood-derived exosomes and single-cell multi-omics data in tumor microenvironment

Background

Kidney renal clear cell carcinoma (KIRC) is the most frequently diagnosed subtype of renal cell carcinoma (RCC); however, the pathogenesis and diagnostic approaches for KIRC remain elusive. Using single-cell transcriptomic information of KIRC, we constructed a diagnostic model depicting the landscape of programmed cell death (PCD)-associated genes, namely cell death-related genes (CDRGs).

Methods

In this study, six CDRG categories, including apoptosis, necroptosis, autophagy, pyroptosis, ferroptosis, and cuproptosis, were collected. RNA sequencing (RNA-seq) data of blood-derived exosomes from the exoRBase database, RNA-seq data of tissues from The Cancer Genome Atlas (TCGA) combined with control samples from the GTEx databases, and single-cell RNA sequencing (scRNA-seq) data from the Gene Expression Omnibus (GEO) database were downloaded. Next, we intersected the differentially expressed genes (DEGs) of the KIRC cohort from exoRBase and the TCGA databases with CDRGs and DEGs obtained from single-cell datasets, further screening out the candidate biomarker genes using clinical indicators and machine learning methods and thus constructing a diagnostic model for KIRC. Finally, we investigated the underlying mechanisms of key genes and their roles in the tumor microenvironment using scRNA-seq, single-cell assays for transposase-accessible chromatin sequencing (scATAC-seq), and the spatial transcriptomics sequencing (stRNA-seq) data of KIRC provided by the GEO database.

Result

We obtained 1,428 samples and 216,155 single cells. After the rational screening, we constructed a 13-gene diagnostic model for KIRC, which had high diagnostic efficacy in the exoRBase KIRC cohort (training set: AUC = 1; testing set: AUC = 0.965) and TCGA KIRC cohort (training set: AUC = 1; testing set: AUC = 0.982), with an additional validation cohort from GEO databases presenting an AUC value of 0.914. The results of a subsequent analysis revealed a specific tumor epithelial cell of TRIB3^high subset. Moreover, the results of a mechanical analysis showed the relatively elevated chromatin accessibility of TRIB3 in tumor epithelial cells in the scATAC data, while stRNA-seq verified that TRIB3 was predominantly expressed in cancer tissues.

Conclusions

The 13-gene diagnostic model yielded high accuracy in KIRC screening, and TRIB3^high tumor epithelial cells could be a promising therapeutic target for KIRC.

The protective effects of miR-210 modified endothelial progenitor cells released exosomes in hypoxia/reoxygenation injured neurons

We have previously demonstrated that endothelial progenitor cells (EPCs) provide beneficial effects on ischemic stroke by reducing oxidative stress, which could be through EPCs-released exosomes (EPC-EXs). EXs are emerging as a bioagent for mediating cell-cell communications via their carried microRNAs (miR). miR-210 is shown to provide a neuroprotection effect against ischemic stroke. Here, we aimed to determine whether the combination of EPC-EXs and miR-210 would provide an enhanced protective effect on neurons. The hypoxia and reoxygenation (H/R) model were applied to neurons to mimic the ischemic injury of neurons. EPCs were transfected with miR-210 mimic to elevate the level of miR-210 in cells and EPC-EXs (miR210-EPC-EXs). For functional studies, EPC-EXs were co-incubated with H/R-injured neurons, then the cell viability and reactive oxygen species (ROS) production were determined. The results showed 1) H/R induced apoptosis and ROS overproduction in neurons; 2) miR-210 mimic increased the level of miR-210 in both EPCs and EPC-EXs; 3) EPCs cultured in serum-free medium released more exosomes in comparison with cells grown in complete growth media, suggesting serum starving induce the release of EXs; 4) After transfection, EPCs grown in complete media had almost 50 times higher miR-210 level than EPCs had in serum-free media, while the EPCs-EXs isolated from the complete media has lower miR-210 expression than from the serum-free media in a time-dependent manner, suggesting the transfer of miR-210 through EXs; 5) After co-incubation, EPC-EXs and miR210-EPC-EXs were uptaken by neurons, and the miR-210 level in neurons was elevated by miR210-EPC-EXs; 6) miR210-EPC-EXs were more effective in promoting cell viability and decreasing apoptosis and ROS production than EPC-EXs. The present study demonstrated that EPCs-carried miR-210 could be released and transferred to neurons in a time-dependent manner and that miR-210 loading can enhance the protective effects of EPC-EXs on H/R-induced neuron apoptosis, oxidative stress, and decreased viability.

Exosomes-based therapy of stroke, an emerging approach toward recovery

Based on clinical observations, stroke is touted as one of the specific pathological conditions, affecting an individual’s life worldwide. So far, no effective treatment has been introduced to deal with stroke post-complications. Production and release of several neurotrophic factors by different cells exert positive effects on ischemic areas following stroke. As a correlate, basic and clinical studies have focused on the development and discovery of de novo modalities to introduce these factors timely and in appropriate doses into the affected areas. Exosomes (Exo) are non-sized vesicles released from many cells during pathological and physiological conditions and participate in intercellular communication. These particles transfer several arrays of signaling molecules, like several neurotrophic factors into the acceptor cells and induce specific signaling cascades in the favor of cell bioactivity. This review aimed to highlight the emerging role of exosomes as a therapeutic approach in the regeneration of ischemic areas.

Exosomes─Nature's Lipid Nanoparticles, a Rising Star in Drug Delivery and Diagnostics

Exosomes are a subgroup of nanosized extracellular vesicles enclosed by a lipid bilayer membrane and secreted by most eukaryotic cells. They represent a route of intercellular communication and participate in a wide variety of physiological and pathological processes. The biological roles of exosomes rely on their bioactive cargos, including proteins, nucleic acids, and lipids, which are delivered to target cells. Their distinctive properties─innate stability, low immunogenicity, biocompatibility, and good biomembrane penetration capacity─allow them to function as superior natural nanocarriers for efficient drug delivery. Another notably favorable clinical application of exosomes is in diagnostics. They hold various biomolecules from host cells, which are indicative of pathophysiological conditions; therefore, they are considered vital for biomarker discovery in clinical diagnostics. Here, we use data from the CAS Content Collection and provide a landscape overview of the current state and delineate trends in research advancement on exosome applications in therapeutics and diagnostics across time, geography, composition, cargo loading, and development pipelines. We discuss exosome composition and pathway, from their biogenesis and secretion from host cells to recipient cell uptake. We assess methods for exosome isolation and purification, their clinical applications in therapy and diagnostics, their development pipelines, the exploration goals of the companies, the assortment of diseases they aim to treat, development stages of their research, and publication trends. We hope this review will be useful for understanding the current knowledge in the field of medical applications of exosomes, in an effort to further solve the remaining challenges in fulfilling their potential.

Stem Cell- and Cell-Based Therapies for Ischemic Stroke

Stroke is the second cause of disability worldwide as it is expected to increase its incidence and prevalence. Despite efforts to increase the number of patients eligible for recanalization therapies, a significant proportion of stroke survivors remain permanently disabled. This outcome boosted the search for efficient neurorestorative methods. Stem cells act through multiple pathways: cell replacement, the secretion of growth factors, promoting endogenous reparative pathways, angiogenesis, and the modulation of neuroinflammation. Although neural stem cells are difficult to obtain, pose a series of ethical issues, and require intracerebral delivery, mesenchymal stem cells are less immunogenic, are easy to obtain, and can be transplanted via intravenous, intra-arterial, or intranasal routes. Extracellular vesicles and exosomes have similar actions and are easier to obtain, also allowing for engineering to deliver specific molecules or RNAs and to promote the desired effects. Appropriate timing, dosing, and delivery protocols must be established, and the possibility of tumorigenesis must be settled. Nonetheless, stem cell- and cell-based therapies for stroke have already entered clinical trials. Although safe, the evidence for efficacy is less impressive so far. Hopefully, the STEP guidelines and the SPAN program will improve the success rate. As such, stem cell- and cell-based therapy for ischemic stroke holds great promise.

The Link between Oxidative Stress, Mitochondrial Dysfunction and Neuroinflammation in the Pathophysiology of Alzheimer's Disease: Therapeutic Implications and Future Perspectives

Alzheimer's disease (AD), the most common form of dementia, has increasing incidence, increasing mortality rates, and poses a huge burden on healthcare. None of the currently approved drugs for the treatment of AD influence disease progression. Many clinical trials aiming at inhibiting amyloid plaque formation, increasing amyloid beta clearance, or inhibiting neurofibrillary tangle pathology yielded inconclusive results or failed. Meanwhile, research has identified many interlinked vicious cascades implicating oxidative stress, mitochondrial dysfunction, and chronic neuroinflammation, and has pointed to novel therapeutic targets such as improving mitochondrial bioenergetics and quality control, diminishing oxidative stress, or modulating the neuroinflammatory pathways. Many novel molecules tested in vitro or in animal models have proven efficient, but their translation into clinic needs further research regarding appropriate doses, delivery routes, and possible side effects. Cell-based therapies and extracellular vesicle-mediated delivery of messenger RNAs and microRNAs seem also promising strategies allowing to target specific signaling pathways, but need further research regarding the most appropriate harvesting and culture methods as well as control of the possible tumorigenic side effects. The rapidly developing area of nanotechnology could improve drug delivery and also be used in early diagnosis.

Double-Stranded RNA Viruses Are Released From Trichomonas vaginalis Inside Small Extracellular Vesicles and Modulate the Exosomal Cargo

Trichomonas vaginalis is a parasitic protist that infects the human urogenital tract. During the infection, trichomonads adhere to the host mucosa, acquire nutrients from the vaginal/prostate environment, and release small extracellular vesicles (sEVs) that contribute to the trichomonad adherence and modulate the host-parasite communication. Approximately 40–70% of T. vaginalis strains harbor a double-stranded RNA virus called Trichomonasvirus (TVV). Naked TVV particles have the potential to stimulate a proinflammatory response in human cells, however, the mode of TVV release from trichomonads to the environment is not clear. In this report, we showed for the first time that TVV particles are released from T. vaginalis cells within sEVs. The sEVs loaded with TVV stimulated a higher proinflammatory response of human HaCaT cells in comparison to sEVs from TVV negative parasites. Moreover, a comparison of T. vaginalis isogenic TVV plus and TVV minus clones revealed a significant impact of TVV infection on the sEV proteome and RNA cargo. Small EVs from TVV positive trichomonads contained 12 enriched and 8 unique proteins including membrane-associated BspA adhesine, and about a 2.5-fold increase in the content of small regulatory tsRNA. As T. vaginalis isolates are frequently infected with TVV, the release of TVV via sEVs to the environment represents an important factor with the potential to enhance inflammation-related pathogenesis during trichomoniasis.

Pivoting Novel Exosome-Based Technologies for the Detection of SARS-CoV-2

The National Institutes of Health (NIH) launched the Rapid Acceleration of Diagnostics (RADx) initiative to meet the needs for COVID-19 diagnostic and surveillance testing, and to speed its innovation in the development, commercialization, and implementation of new technologies and approaches. The RADx Radical (RADx-Rad) initiative is one component of the NIH RADx program which focuses on the development of new or non-traditional applications of existing approaches, to enhance their usability, accessibility, and/or accuracy for the detection of SARS-CoV-2. Exosomes are a subpopulation of extracellular vesicles (EVs) 30–140 nm in size, that are critical in cell-to-cell communication. The SARS-CoV-2 virus has similar physical and molecular properties as exosomes. Therefore, the novel tools and technologies that are currently in development for the isolation and detection of exosomes, may prove to be invaluable in screening for SARS-CoV-2 viral infection. Here, we describe how novel exosome-based technologies are being pivoted for the detection of SARS-CoV-2 and/or the diagnosis of COVID-19. Considerations for these technologies as they move toward clinical validation and commercially viable diagnostics is discussed along with their future potential. Ultimately, the technologies in development under the NIH RADx-Rad exosome-based non-traditional technologies toward multi-parametric and integrated approaches for SARS-CoV-2 program represent a significant advancement in diagnostic technology, and, due to a broad focus on the biophysical and biochemical properties of nanoparticles, the technologies have the potential to be further pivoted as tools for future infectious agents.

Application of extracellular vesicles derived from mesenchymal stem cells as potential therapeutic tools in autoimmune and rheumatic diseases

Mesenchymal stem cells (MSCs) have been proven to have superior potential to be used astherapeutic candidates in various disorders. Nevertheless, the clinical application of these cells have been restricted because of their tumorigenic properties. Increasing evidence has established that the valuable impacts of MSCs are mainly attributable to the paracrine factors including extracellular vesicles (EVs). EVs are nanosized double-layer phospholipid membrane vesicles contain various proteins, lipids and miRNAs which mediate cell-to-cell communications. Due to their inferior immunogenicity and tumorigenicity, as well as easier management, EVs have drawn attention as potential cell-free replacement therapy to MSCs. For that reason, herein, we reviewed the recent findings of researches on different MSC-EVs and their effectiveness in the treatment of several autoimmune and rheumatic diseases including multiple sclerosis, inflammatory bowel disease, rheumatoid arthritis, osteoarthritis, osteoporosis, and systemic lupus erythematosus as well as Sjogren's syndrome, systemic sclerosis and other autoimmune diseases.

Harnessing the Therapeutic Potential of Extracellular Vesicles for Biomedical Applications Using Multifunctional Magnetic Nanomaterials

Extracellular vesicles (e.g., exosomes) carrying various biomolecules (e.g., proteins, lipids, and nucleic acids) have rapidly emerged as promising platforms for many biomedical applications. Despite their enormous potential, their heterogeneity in surfaces and sizes, the high complexity of cargo biomolecules, and the inefficient uptake by recipient cells remain critical barriers for their theranostic applications. To address these critical issues, multifunctional nanomaterials, such as magnetic nanomaterials, with their tunable physical, chemical, and biological properties, may play crucial roles in next-generation extracellular vesicles (EV)-based disease diagnosis, drug delivery, tissue engineering, and regenerative medicine. As such, one aims to provide cutting-edge knowledge pertaining to magnetic nanomaterials-facilitated isolation, detection, and delivery of extracellular vesicles and their associated biomolecules. By engaging the fields of extracellular vesicles and magnetic nanomaterials, it is envisioned that their properties can be effectively combined for optimal outcomes in biomedical applications.

Semen Extracellular Vesicles Mediate Vertical Transmission of Subgroup J Avian Leukosis Virus

Subgroup J avian leukosis virus (ALV-J) is a highly oncogenic retrovirus that has been devastating the global poultry industry since the late 1990s. The major infection model of ALV-J is vertical transmission, which is responsible for the congenital infection of progeny from generation to generation. Increasing evidence has suggested that extracellular vesicles (EVs) derived from virus-infected cells or biological fluids have been thought to be vehicles of transmission for viruses. However, the role of EVs in infection and transmission of ALV-J remains obscure. In the present study, semen extracellular vesicles (SE) were isolated and purified from ALV-J-infected rooster seminal plasma (SE-ALV-J), which was shown to contain ALV-J genomic RNA and partial viral proteins, as determined by RNA sequencing, reverse transcription-quantitative PCR and Western blotting. Furthermore, SE-ALV-J was proved to be able to transmit ALV-J infection to host cells and establish productive infection. More importantly, artificial insemination experiments showed that SE-ALV-J transmitted ALV-J infection to SPF hens, and subsequently mediated vertical transmission of ALV-J from the SPF hens to the progeny chicks. Taken together, the results of the present study suggested that ALV-J utilized host semen extracellular vesicles as a novel means for vertical transmission, enhancing our understanding on mechanisms underlying ALV-J transmission.

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SE-ALV-J- contains ALV-J genomic RNA and partial viral proteins.

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SE-ALV-J could transmit ALV-J infection to host cells and establish productive infection.

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SE-ALV-J mediates vertical transmission of ALV-J in animal model.

Extracellular vesicles in pharmacology: Novel approaches in diagnostics and therapy

Exosomes are nano-sized lipid vesicles that are produced by all eukaryotic cells, and they typically range in size from 30 to 150 nm. Exosomes were discovered almost 40 years ago; however, the last two decades have attracted considerable attention due to exosomes' inherent abilities to shuttle nucleic acids, lipids and proteins between cells, along with their natural affinity to exosome target cells. From a pharmaceutical perspective, exosomes are regarded as naturally produced nanoparticle drug delivery vehicles. The application of exosomes as a means of drug delivery offers critical advantages compared to other nanoparticulate drug delivery systems, such as liposomes and polymeric nanoparticles. These advantages are due to the exosomes' intrinsic features, such as low immunogenicity, biocompatibility, stability, and their ability to overcome biological barriers. Herein, we outline the structure and origin of exosomes, as well as their biological functions. We also touch upon recent advances in exosome labeling, imaging and drug loading. Finally, we discuss exosomes in targeted drug delivery and clinical trial development.

Exosomes and COVID-19: challenges and opportunities

Coronavirus disease 2019 or COVID-19, starting from Wuhan, China, in December 2019, is a pandemic situation affecting millions worldwide and has exerted a huge burden on healthcare infrastructure. Therefore, there is an urgent need to understand the molecular mechanisms underlying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and design novel effective therapeutic strategies for combating this pandemic. In this regard, special attention has been paid to the exosomes. These nanoparticles are extracellular vesicles with critical function in the pathogenesis of several diseases including viral sepsis. Therefore, they may be involved in the pathogenesis of COVID-19 infection and also may be a way for transferring viral components and infecting other neighbor cells. Exosomes also can be considered as a therapeutic strategy for treating COVID-19 patients or used as a carrier for delivering effective therapeutic agents. Therefore, in this review, we discussed the biogenesis and contents of exosomes, their function in viral infection, and their potential as a therapeutic candidate in treating COVID-19.

Application of Stem Cell-Derived Extracellular Vesicles as an Innovative Theranostics in Microbial Diseases

Extracellular vesicles (EVs), as nano-/micro-scale vehicles, are membranous particles containing various cargoes including peptides, proteins, different types of RNAs and other nucleic acids, and lipids. These vesicles are produced by all cell types, in which stem cells are a potent source for them. Stem cell-derived EVs could be promising platforms for treatment of infectious diseases and early diagnosis. Infectious diseases are responsible for more than 11 million deaths annually. Highly transmissible nature of some microbes, such as newly emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), drives researcher's interest to set up different strategies to develop novel therapeutic strategies. Recently, EVs-based diagnostic and therapeutic approaches have been launched and gaining momentum very fast. The efficiency of stem cell-derived EVs on treatment of clinical complications of different viruses and bacteria, such as SARS-CoV-2, hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), Staphylococcus aureus, Escherichia coli has been demonstrated. On the other hand, microbial pathogens are able to incorporate their components into their EVs. The microbe-derived EVs have different physiological and pathological impacts on the other organisms. In this review, we briefly discussed biogenesis and the fate of EVs. Then, EV-based therapy was described and recent developments in understanding the potential application of stem cell-derived EVs on pathogenic microorganisms were recapitulated. Furthermore, the mechanisms by which EVs were exploited to fight against infectious diseases were highlighted. Finally, the deriver challenges in translation of stem cell-derived EVs into the clinical arena were explored.

Human Adenovirus Serotype 3 Infection Modulates the Biogenesis and Composition of Lung Cell-Derived Extracellular Vesicles

Adenovirus (Ad) is a major causal agent of acute respiratory infections. However, they are a powerful delivery system for gene therapy and vaccines. Some Ad serotypes antagonize the immune system leading to meningitis, conjunctivitis, gastroenteritis, and/or acute hemorrhagic cystitis. Studies have shown that the release of small, membrane-derived extracellular vesicles (EVs) may offer a mechanism by which viruses can enter cells via receptor-independent entry and how they influence disease pathogenesis and/or host protection considering their existence in almost all bodily fluids. We proposed that Ad3 could alter EV biogenesis, composition, and trafficking and may stimulate various immune responses in vitro. In the present study, we evaluated the impact of in vitro infection with Ad3 vector on EV biogenesis and composition in the human adenocarcinoma lung epithelial cell line A549. Cells were infected in an exosome-free media at different multiplicity of infections (MOIs) and time points. The cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and fluorometric calcein-AM. EVs were isolated via ultracentrifugation. Isolated EV proteins were quantified and evaluated via nanoparticle tracking, transmission electron microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblotting assays. The cell viability significantly decreased with an increase in MOI and incubation time. A significant increase in particle mean sizes, concentrations, and total EV protein content was detected at higher MOIs when compared to uninfected cells (control group). A549 cell-derived EVs revealed the presence of TSG101, tetraspanins CD9 and CD63, and heat shock proteins 70 and 100 with significantly elevated levels of Rab5, 7, and 35 at higher MOIs (300, 750, and 1500) when compared to the controls. Our findings suggested Ad3 could modulate EV biogenesis, composition, and trafficking which could impact infection pathogenesis and disease progression. This study might suggest EVs could be diagnostic and therapeutic advancement to Ad infections and other related viral infections. However, further investigation is warranted to explore the underlying mechanism(s).

Cutting Edge: Circulating Exosomes with COVID Spike Protein Are Induced by BNT162b2 (Pfizer-BioNTech) Vaccination prior to Development of Antibodies: A Novel Mechanism for Immune Activation by mRNA Vaccines

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) causes severe acute respiratory syndrome. mRNA vaccines directed at the SARS-CoV-2 spike protein resulted in development of Abs and protective immunity. To determine the mechanism, we analyzed the kinetics of induction of circulating exosomes with SARS-CoV-2 spike protein and Ab following vaccination of healthy individuals. Results demonstrated induction of circulating exosomes expressing spike protein on day 14 after vaccination followed by Abs 14 d after the second dose. Exosomes with spike protein, Abs to SARS-CoV-2 spike, and T cells secreting IFN-γ and TNF-α increased following the booster dose. Transmission electron microscopy of exosomes also demonstrated spike protein Ags on their surface. Exosomes with spike protein and Abs decreased in parallel after four months. These results demonstrate an important role of circulating exosomes with spike protein for effective immunization following mRNA-based vaccination. This is further documented by induction of humoral and cellular immune responses in mice immunized with exosomes carrying spike protein.

Development of surface engineered antigenic exosomes as vaccines for respiratory syncytial virus

Respiratory syncytial virus (RSV) is one of the main pathogens associated with lower respiratory tract infections in infants and young children worldwide. Exosomes secreted by antigen presenting cells (APCs) can elicit immune responses by carrying major histocompatibility complex (MHC) class I molecules complexed with antigenic peptides and other co-stimulating factors. Therefore, we developed novel immunomagnetic nanographene particles to sequentially isolate, surface engineer, and release intact dendritic cell (DC) exosomes for use as a potential vaccine platform against RSV. The H-2Db-restricted, immunodominant peptides from RSV (M187-195 and NS161-75) were introduced to MHC-I on DC-derived exosomes to express peptide/MHC-I (pMHC-I) complexes. A mouse model of RSV infection was used to define the immunogenicity of surface engineered exosomes for activating virus-specific immune responses. Ex vivo assays demonstrated that engineered exosomes carrying RSV-specific peptides can elicit interferon-gamma (IFN-γ) production by virus-specific CD8+ T cells isolated from RSV-infected C57BL/6 mice. In vivo assays demonstrated that subcutaneous administration of both M187-195 and NS161-75 engineered exosomes to mice, with or without additional adjuvant, appeared safe and well tolerated, however, did not prime antigen-specific CD8+ T cell responses. Surface engineered exosomes are immunogenic and promising for further development as a vaccine platform.

Evidence for a Novel Antiviral Mechanism of Teleost Fish: Serum-Derived Exosomes Inhibit Virus Replication through Incorporating Mx1 Protein

Exosomes are associated with cancer progression, pregnancy, cardiovascular diseases, central nervous system-related diseases, immune responses and viral pathogenicity. However, study on the role of exosomes in the immune response of teleost fish, especially antiviral immunity, is limited. Herein, serum-derived exosomes from mandarin fish were used to investigate the antiviral effect on the exosomes of teleost fish. Exosomes isolated from mandarin fish serum by ultra-centrifugation were internalized by mandarin fish fry cells and were able to inhibit Infectious spleen and kidney necrosis virus (ISKNV) infection. To further investigate the underlying mechanisms of exosomes in inhibiting ISKNV infection, the protein composition of serum-derived exosomes was analyzed by mass spectrometry. It was found that myxovirus resistance 1 (Mx1) was incorporated by exosomes. Furthermore, the mandarin fish Mx1 protein was proven to be transferred into the recipient cells though exosomes. Our results showed that the serum-derived exosomes from mandarin fish could inhibit ISKNV replication, which suggested an underlying mechanism of the exosome antivirus in that it incorporates Mx1 protein and delivery into recipient cells. This study provided evidence for the important antiviral role of exosomes in the immune system of teleost fish.

The biology, function, and applications of exosomes in cancer

Exosomes are cell-derived nanovesicles with diameters from 30 to 150 nm, released upon fusion of multivesicular bodies with the cell surface. They can transport nucleic acids, proteins, and lipids for intercellular communication and activate signaling pathways in target cells. In cancers, exosomes may participate in growth and metastasis of tumors by regulating the immune response, blocking the epithelial-mesenchymal transition, and promoting angiogenesis. They are also involved in the development of resistance to chemotherapeutic drugs. Exosomes in liquid biopsies can be used as non-invasive biomarkers for early detection and diagnosis of cancers. Because of their amphipathic structure, exosomes are natural drug delivery vehicles for cancer therapy.

Exosomes as New Biomarkers and Drug Delivery Tools for the Prevention and Treatment of Various Diseases: Current Perspectives

Exosomes are nano-sized vesicles secreted by most cells that contain a variety of biological molecules, such as lipids, proteins and nucleic acids. They have been recognized as important mediators for long-distance cell-to-cell communication and are involved in a variety of biological processes. Exosomes have unique advantages, positioning them as highly effective drug delivery tools and providing a distinct means of delivering various therapeutic agents to target cells. In addition, as a new clinical diagnostic biomarker, exosomes play an important role in many aspects of human health and disease, including endocrinology, inflammation, cancer, and cardiovascular disease. In this review, we summarize the development of exosome-based drug delivery tools and the validation of novel biomarkers, and illustrate the role of exosomes as therapeutic targets in the prevention and treatment of various diseases.

A Role for Extracellular Vesicles in SARS-CoV-2 Therapeutics and Prevention

Extracellular vesicles (EVs) are the common designation for ectosomes, microparticles and microvesicles serving dominant roles in intercellular communication. Both viable and dying cells release EVs to the extracellular environment for transfer of cell, immune and infectious materials. Defined morphologically as lipid bi-layered structures EVs show molecular, biochemical, distribution, and entry mechanisms similar to viruses within cells and tissues. In recent years their functional capacities have been harnessed to deliver biomolecules and drugs and immunological agents to specific cells and organs of interest or disease. Interest in EVs as putative vaccines or drug delivery vehicles are substantial. The vesicles have properties of receptors nanoassembly on their surface. EVs can interact with specific immunocytes that include antigen presenting cells (dendritic cells and other mononuclear phagocytes) to elicit immune responses or affect tissue and cellular homeostasis or disease. Due to potential advantages like biocompatibility, biodegradation and efficient immune activation, EVs have gained attraction for the development of treatment or a vaccine system against the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection. In this review efforts to use EVs to contain SARS CoV-2 and affect the current viral pandemic are discussed. An emphasis is made on mesenchymal stem cell derived EVs' as a vaccine candidate delivery system.

Role of Extracellular Vesicles in Glioma Progression: Deciphering Cellular Biological Processes to Clinical Applications

Glioma predominantly targets glial cells in the brain and spinal cord. There are grade I, II, III, and IV gliomas with anaplastic astrocytoma and glioblastoma multiforme as the most severe forms of the disease. Current diagnostic methods are limited in their data acquisition and interpretation, markedly affecting treatment modalities, and patient outcomes. Circulating extracellular vesicles (EVs) or "magic bullets" contain bioactive signature molecules such as DNA, RNA, proteins, lipids, and metabolites. These secretory "smart probes" participate in myriad cellular activities, including glioma progression. EVs are released by all cell populations and may serve as novel diagnostic biomarkers and efficient nano-vehicles in the targeted delivery of encapsulated therapeutics. The present review describes the potential of EV-based biomarkers for glioma management.

The Significance of Phenotyping and Quantification of Plasma Extracellular Vesicles Levels Using High-Sensitivity Flow Cytometry during COVID-19 Treatment

New investigation results point to the potential participation of extracellular vesicles (EVs) in the pathogenesis of coronavirus infection, its progression, and mechanisms of the therapy effectiveness. This dictates the necessity to transfer scientific testing technologies to medical practice. Here, we demonstrated the method of phenotyping and quantitative analysis of plasma EVs based on differential centrifugation, immunostaining, and high-sensitivity multicolor flow cytometry. We used EV markers that were potentially associated with SARS-CoV-2 dissemination via vesicles and cell-origination markers, characterizing objects from different cell types that could influence clinical manifestation of COVID-19. Plasma levels of CD235a+ and CD14+ EVs in patients with moderate infection were significantly increased while CD8+ and CD19+ EVs were decreased comparing with HD. Patients with severe infection had lower levels of CD4+, CD19+, and CD146+ EVs than HD. These findings demonstrate that EV concentrations in COVID-19 are severity related. Moreover, the three-point dynamic assessment demonstrated significant loss of CD63+ and CD147+ plasma EVs. The used method can be a convenient tool for vital infection pathogenesis investigation and for COVID-19 diagnostics.

MSC-derived exosomes carrying a cocktail of exogenous interfering RNAs an unprecedented therapy in era of COVID-19 outbreak

BACKGROUND

The onset of the SARS-CoV-2 pandemic has resulted in ever-increasing casualties worldwide, and after 15 months, standard therapeutic regimens are yet to be discovered.

MAIN BODY

Due to the regenerative and immunomodulatory function of MSCs, they can serve as a suitable therapeutic option in alleviating major COVID-19 complications like acute respiratory distress syndrome. However, the superior properties of their cognate exosomes as a cell-free product make them preferable in the clinic. Herein, we discuss the current clinical status of these novel therapeutic strategies in COVID-19 treatment. We then delve into the potential of interfering RNAs incorporation as COVID-19 gene therapy and introduce targets involved in SARS-CoV-2 pathogenesis. Further, we present miRNAs and siRNAs candidates with promising results in targeting the mentioned targets.

CONCLUSION

Finally, we present a therapeutic platform of mesenchymal stem cell-derived exosomes equipped with exogenous iRNAs, that can be employed as a novel therapeutic modality in COVID-19 management aiming to prevent further viral spread within the lung, hinder the virus life cycle and pathogenesis such as immune suppression, and ultimately, enhance the antiviral immune response.

Small Extracellular Vesicles: A Novel Avenue for Cancer Management

Extracellular vesicles are small membrane particles derived from various cell types. EVs are broadly classified as ectosomes or small extracellular vesicles, depending on their biogenesis and cargoes. Numerous studies have shown that EVs regulate multiple physiological and pathophysiological processes. The roles of small extracellular vesicles in cancer growth and metastasis remain to be fully elucidated. As endogenous products, small extracellular vesicles are an ideal drug delivery platform for anticancer agents. However, several aspects of small extracellular vesicle biology remain unclear, hindering the clinical implementation of small extracellular vesicles as biomarkers or anticancer agents. In this review, we summarize the utility of cancer-related small extracellular vesicles as biomarkers to detect early-stage cancers and predict treatment outcomes. We also review findings from preclinical and clinical studies of small extracellular vesicle-based cancer therapies and summarize interventional clinical trials registered in the United States Food and Drug Administration and the Chinese Clinical Trials Registry. Finally, we discuss the main challenges limiting the clinical implementation of small extracellular vesicles and recommend possible approaches to address these challenges.

The Potential Role of Exosomes in Child and Adolescent Obesity

Child and adolescent obesity constitute one of the greatest contemporary public health menaces. The enduring disproportion between calorie intake and energy consumption, determined by a complex interaction of genetic, epigenetic, and environmental factors, finally leads to the development of overweight and obesity. Child and adolescent overweight/obesity promotes smoldering systemic inflammation (“para-inflammation”) and increases the likelihood of later metabolic and cardiovascular complications, including metabolic syndrome and its components, which progressively deteriorate during adulthood. Exosomes are endosome-derived extracellular vesicles that are secreted by a variety of cells, are naturally taken-up by target cells, and may be involved in many physiological and pathological processes. Over the last decade, intensive research has been conducted regarding the special role of exosomes and the non-coding (nc) RNAs they contain (primarily micro (mi) RNAs, long (l) non-coding RNAs, messenger (m) RNAs and other molecules) in inter-cellular communications. Through their action as communication mediators, exosomes may contribute to the pathogenesis of obesity and associated disorders. There is increasing evidence that exosomal miRNAs and lncRNAs are involved in pivotal processes of adipocyte biology and that, possibly, play important roles in gene regulation linked to human obesity. This review aims to improve our understanding of the roles of exosomes and their cargo in the development of obesity and related metabolic and inflammatory disorders. We examined their potential roles in adipose tissue physiology and reviewed the scarce data regarding the altered patterns of circulating miRNAs and lncRNAs observed in obese children and adolescents, compared them to the equivalent, more abundant existing findings of adult studies, and speculated on their proposed mechanisms of action. Exosomal miRNAs and lncRNAs could be applied as cardiometabolic risk biomarkers, useful in the early diagnosis and prevention of obesity. Furthermore, the targeting of crucial circulating exosomal cargo to tissues involved in the pathogenesis and maintenance of obesity could provide a novel therapeutic approach to this devastating and management-resistant pandemic.