Tumor-derived exosomes regulate expression of immune function-related genes in human T cell subsets. Sci Rep. 2016;6:20254. [PMID: 26842680 PMCID: PMC4740743 DOI: 10.1038/srep20254]

Exercise-Induced Extracellular Vesicles Delay the Progression of Prostate Cancer

Increasing evidence suggests that regular physical exercise not only reduces the risk of cancer but also improves functional capacity, treatment efficacy and disease outcome in cancer patients. At least partially, these effects are mediated by the secretome of the tissues responding to exercise. The secreted molecules can be released in a carrier-free form or enclosed into extracellular vesicles (EVs). Several recent studies have shown that EVs are actively released into circulation during physical exercise. Here, we for the first time investigated the effects of exercise-induced EVs on the progression of cancer in an F344 rat model of metastatic prostate cancer. Although we did not observe a consistent increase in the circulating EV levels, RNA sequencing analysis demonstrated substantial changes in the RNA content of EVs collected before and immediately after forced wheel running exercise as well as differences between EVs from runners at resting state and sedentary rats. The major RNA biotype in EVs was mRNA, followed by miRNA and rRNA. Molecular functions of differentially expressed RNAs reflected various physiological processes including protein folding, metabolism and regulation of immune responses triggered by the exercise in the parental cells. Intravenous administration of exercise-induced EVs into F344 rats with orthotopically injected syngeneic prostate cancer cells PLS10, demonstrated reduction of the primary tumor volume by 35% and possibly—attenuation of lung metastases. Hence, our data provide the first evidence that exercise-induced EVs may modulate tumor physiology and delay the progression of cancer.

Small extracellular vesicles: from mediating cancer cell metastasis to therapeutic value in pancreatic cancer

Pancreatic cancer is a highly malignant tumor and, is extremely difficult to diagnose and treat. Metastasis is one of the critical steps in the development of cancer and uses cell to cell communication to mediate changes in the microenvironment. Small extracellular vesicles (sEVs)-carry proteins, nucleic acids and other bioactive substances, and are important medium for communication between cells. There are two primary steps in sVEs-mediated metastasis: communication between pancreatic cancer cells and their surrounding microenvironment; and the communication between primary tumor cells and distant organ cells in distant organs that promotes angiogenesis, reshaping extracellular matrix, forming immunosuppressive environment and other ways to form appropriate pre-metastasis niche. Here, we explore the mechanism of localization and metastasis of pancreatic cancer and use sEVs as early biomarkers for the detection and treatment of pancreatic cancer. Video Abstract.

Exosomes in cancer immunoediting and immunotherapy

As an important means of communication among cells, exosomes are being studied more and more widely, especially in the context of cancer immunotherapy. In the phase of tumor immunoediting, exosomes derived from tumor cells and different immune cells have complex and changeable physiological functions, because they carry different proteins and nucleic acid from the source cells. Based on the role of exosomes in the communication between different cells, cancer treatment methods are also under continuous research. This review briefly introduces the molecular composition of exosomes, which is closely related to their secretion mechanism. Subsequently, the role of exosomes encapsulating different information molecules is summarized. The role of exosomes in the three phases of tumor immunoediting is introduced in detail, and the relevant literature of exosomes in the tumor immune microenvironment is summarized by using a novel framework for extracting relevant documents. Finally, it summarizes the various exosome-based immunotherapies currently proposed, as well as the challenges and future prospects of exosomes in tumor immunotherapy.

Analysis of vitamin D metabolic markers by mass spectrometry: Recent progress regarding the "gold standard" method and integration into clinical practice

Liquid chromatography/tandem mass spectrometry is firmly established today as the gold standard technique for analysis of vitamin D, both for vitamin D status assessments as well as for measuring complex and intricate vitamin D metabolic fingerprints. While the actual mass spectrometry technology has seen only incremental performance increases in recent years, there have been major, very impactful changes in the front- and back-end of MS-based vitamin D assays; for example, the extension to new types of biological sample matrices analyzed for an increasing number of different vitamin D metabolites, novel sample preparation techniques, new powerful chemical derivatization reagents, as well the continued integration of high resolution mass spectrometers into clinical laboratories, replacing established triple-quadrupole instruments. At the same time, the sustainability of mass spectrometry operation in the vitamin D field is now firmly established through proven analytical harmonization and standardization programs. The present review summarizes the most important of these recent developments.

The interweaving relationship between extracellular vesicles and T cells in cancer

The interdependency between cancer cells and immune cells is an important link in understanding cancer pathogenesis. T cells are important immune cells that are able to either impede or promote tumor growth. Extracellular vesicles or EVs are membrane-encapsulated vesicles that are released by both cancer and immune cells that can act as communicators. Studies have shown that tumor-derived EVs can interact with immune cells, particularly T cells. Vice versa, T cells-derived EVs have also been shown to possess immunomodulatory roles. Therefore, the purpose of this mini-review is to understand the role of tumor-derived EVs and T-cells derived EVs on cancer immunosuppression especially the interweaving role of different types of EVs and how it affects tumor immunity. We also discuss the role of EVs in different types of T cells namely CD8⁺, CD4⁺ Th17 and Treg cells. More importantly, we include the limitations and future directions involving this type of research. This will further elucidate our understanding of the important functions of these tiny mediators.

The Role of Tumor-Derived Exosomes (TEX) in Shaping Anti-Tumor Immune Competence

Emerging studies suggest that extracellular vesicles (EVs) mediating intercellular communication in the tumor microenvironment (TME) play a key role in driving cancer progression. Tumor-derived small EVs or exosomes (TEX) enriched in immunosuppressive proteins or in microRNAs targeting suppressive pathways in recipient cells contribute to reprogramming the TME into a cancer-promoting milieu. The adenosinergic pathway is an acknowledged major contributor to tumor-induced immune suppression. TEX carry the components of this pathway and utilize ATP to produce adenosine (ADO). TEX-associated ADO emerges as a key factor in the suppression of T cell responses to therapy. Here, the significance of the ADO pathway in TEX is discussed as a highly effective mechanism of cancer-driven immune cell suppression and of resistance to immune therapies.

Multiple Myeloma Cell-Derived Exosomes: Implications on Tumorigenesis, Diagnosis, Prognosis and Therapeutic Strategies

Multiple myeloma (MM) is a hematological disease that is still not curable. The bone marrow milieu, with cellular and non-cellular elements, participate in the creation of a pro-tumoral environment enhancing growth and survival of MM plasma cells. Exosomes are vesicles oscillating in dimension between 50 nm and 100 nm in size that can be released by various cells and contribute to the pathogenesis and progression of MM. Exosomes enclose proteins, cytokines, lipids, microRNAs, long noncoding RNAs, and circular RNAs able to regulate interactions between MM plasma cells and adjacent cells. Through exosomes, mesenchymal stem cells confer chemoresistance to MM cells, while myeloma cells promote angiogenesis, influence immune response, cause bone lesions, and have an impact on the outcome of MM patients. In this review, we analyze the role played by exosomes in the progression of monoclonal gammopathies and the effects on the proliferation of neoplastic plasma cells, and discuss the possible employment of exosomes as potential targets for the treatment of MM patients.

Emerging role of tumor-derived extracellular vesicles in T cell suppression and dysfunction in the tumor microenvironment

Immunotherapeutic drugs including immune checkpoint blockade antibodies have been approved to treat patients in many types of cancers. However, some patients have little or no reaction to the immunotherapy drugs. The mechanisms underlying resistance to tumor immunotherapy are complicated and involve multiple aspects, including tumor-intrinsic factors, formation of immunosuppressive microenvironment, and alteration of tumor and stromal cell metabolism in the tumor microenvironment. T cell is critical and participates in every aspect of antitumor response, and T cell dysfunction is a severe barrier for effective immunotherapy for cancer. Emerging evidence indicates that extracellular vesicles (EVs) secreted by tumor is one of the major factors that can induce T cell dysfunction. Tumor-derived EVs are widely distributed in serum, tissues, and the tumor microenvironment of patients with cancer, which serve as important communication vehicles for cancer cells. In addition, tumor-derived EVs can carry a variety of immune suppressive signals driving T cell dysfunction for tumor immunity. In this review, we explore the potential mechanisms employed by tumor-derived EVs to control T cell development and effector function within the tumor microenvironment. Especially, we focus on current understanding of how tumor-derived EVs molecularly and metabolically reprogram T cell fates and functions for tumor immunity. In addition, we discuss potential translations of targeting tumor-derived EVs to reconstitute suppressive tumor microenvironment or to develop antigen-based vaccines and drug delivery systems for cancer immunotherapy.

Novel phosphatidylserine-binding molecule enhances antitumor T-cell responses by targeting immunosuppressive exosomes in human tumor microenvironments

Background

The human tumor microenvironment (TME) is a complex and dynamic milieu of diverse acellular and cellular components, creating an immunosuppressive environment, which contributes to tumor progression. We have previously shown that phosphatidylserine (PS) expressed on the surface of exosomes isolated from human TMEs is causally linked to T-cell immunosuppression, representing a potential immunotherapeutic target. In this study, we investigated the effect of ExoBlock, a novel PS-binding molecule, on T-cell responses in the TME.

Methods

We designed and synthesized a new compound, (ZnDPA)₆-DP-15K, a multivalent PS binder named ExoBlock. The PS-binding avidity of ExoBlock was tested using an in vitro competition assay. The ability of this molecule to reverse exosome-mediated immunosuppression in vitro was tested using human T-cell activation assays. The in vivo therapeutic efficacy of ExoBlock was then tested in two different human tumor xenograft models, the melanoma-based xenomimetic (X-)mouse model, and the ovarian tumor-based omental tumor xenograft (OTX) model.

Results

ExoBlock was able to bind PS with high avidity and was found to consistently and significantly block the immunosuppressive activity of human ovarian tumor and melanoma-associated exosomes in vitro. ExoBlock was also able to significantly enhance T cell-mediated tumor suppression in vivo in both the X-mouse and the OTX model. In the X-mouse model, ExoBlock suppressed tumor recurrence in a T cell-dependent manner. In the OTX model, ExoBlock treatment resulted in an increase in the number as well as function of CD4 and CD8 T cells in the TME, which was associated with a reduction in tumor burden and metastasis, as well as in the number of circulating PS+ exosomes in tumor-bearing mice.

Conclusion

Our results establish that targeting exosomal PS in TMEs with ExoBlock represents a promising strategy to enhance antitumor T-cell responses.

Biological Functions Driven by mRNAs Carried by Extracellular Vesicles in Cancer

Extracellular vesicles (EVs), including exosomes and microvesicles, are extracellular nanovesicles released by most cells. EVs play essential roles in intercellular communication via the transport of a large variety of lipids, proteins, and nucleic acids to recipient cells. Nucleic acids are the most commonly found molecules inside EVs, and due to their small size, microRNAs and other small RNAs are the most abundant nucleic acids. However, longer molecules, such as messenger RNAs (mRNAs), have also been found. mRNAs encapsulated within EVs have been shown to be transferred to recipient cells and translated into proteins, altering the behavior of the cells. Secretion of EVs is maintained not only through multiple normal physiological conditions but also during aberrant pathological conditions, including cancer. Recently, the mRNAs carried by EVs in cancer have attracted great interest due to their broad roles in tumor progression and microenvironmental remodeling. This review focuses on the biological functions driven by mRNAs carried in EVs in cancer, which include supporting tumor progression by activating cancer cell growth, migration, and invasion; inducing microenvironmental remodeling via hypoxia, angiogenesis, and immunosuppression; and promoting modulation of the microenvironment at distant sites for the generation of a premetastatic niche, collectively inducing metastasis. Furthermore, we describe the potential use of mRNAs carried by EVs as a noninvasive diagnostic tool and novel therapeutic approach.

The PEMDAC phase 2 study of pembrolizumab and entinostat in patients with metastatic uveal melanoma

Preclinical studies have suggested that epigenetic therapy could enhance immunogenicity of cancer cells. We report the results of the PEMDAC phase 2 clinical trial (n = 29; NCT02697630) where the HDAC inhibitor entinostat was combined with the PD-1 inhibitor pembrolizumab in patients with metastatic uveal melanoma (UM). The primary endpoint was objective response rate (ORR), and was met with an ORR of 14%. The clinical benefit rate at 18 weeks was 28%, median progression free survival was 2.1 months and the median overall survival was 13.4 months. Toxicities were manageable, and there were no treatment-related deaths. Objective responses and/or prolonged survival were seen in patients with BAP1 wildtype tumors, and in one patient with an iris melanoma that exhibited a UV signature. Longer survival also correlated with low baseline ctDNA levels or LDH. In conclusion, HDAC inhibition and anti-PD1 immunotherapy results in durable responses in a subset of patients with metastatic UM.Trial registration ClinicalTrials.gov registration number: NCT02697630 (registered 3 March 2016). EudraCT registration number: 2016-002114-50.

On the mechanism of anti-CD39 immune checkpoint therapy

With the coming of age of cancer immunotherapy, the search for new therapeutic targets has led to the identification of immunosuppressive adenosine as an important regulator of antitumor immunity. This resulted in the development of selective inhibitors targeting various components of the adenosinergic pathway, including small molecules antagonists targeting the high affinity A2A adenosine receptor and low affinity A2B receptor, therapeutic monoclonal antibodies (mAbs) and small molecules targeting CD73 and therapeutic mAbs targeting CD39. As each regulator of the adenosinergic pathway present non-overlapping biologic functions, a better understanding of the mechanisms of action of each targeted approach should accelerate clinical translation and improve rational design of combination treatments. In this review, we discuss the potential mechanisms-of-action of anti-CD39 cancer therapy and potential toxicities that may emerge from sustained CD39 inhibition. Caution should be taken, however, in extrapolating data from gene-targeted mice to patients treated with blocking anti-CD39 agents. As phase I clinical trials are now underway, further insights into the mechanism of action and potential adverse events associated with anti-CD39 therapy are anticipated in coming years.

Extracellular vesicles regulate purinergic signaling and epithelial sodium channel expression in renal collecting duct cells

Purinergic signaling regulates several renal physiological and pathophysiological processes. Extracellular vesicles (EVs) are nanoparticles released by most cell types, which, in non-renal tissues, modulate purinergic signaling. The aim of this study was to investigate the effect of EVs from renal proximal tubule (HK2) and collecting duct cells (HCD) on intra- and intersegment modulation of extracellular ATP levels, the underlying molecular mechanisms, and the impact on the expression of the alpha subunit of the epithelial sodium channel (αENaC). HK2 cells were exposed to HK2 EVs, while HCD cells were exposed to HK2 and HCD EVs. Extracellular ATP levels and αENaC expression were measured by chemiluminescence and qRT-PCR, respectively. ATPases in EV populations were identified by mass spectrometry. The effect of aldosterone was assessed using EVs from aldosterone-treated cells and urinary EVs (uEVs) from primary aldosteronism (PA) patients. HK2 EVs downregulated ectonucleoside-triphosphate-diphosphohydrolase-1 (ENTPD1) expression, increased extracellular ATP and downregulated αENaC expression in HCD cells. ENTPD1 downregulation could be attributed to increased miR-205-3p and miR-505 levels. Conversely, HCD EVs decreased extracellular ATP levels and upregulated αENaC expression in HCD cells, probably due to enrichment of 14-3-3 isoforms with ATPase activity. Pretreatment of donor cells with aldosterone or exposure to uEVs from PA patients enhanced the effects on extracellular ATP and αENaC expression. We demonstrated inter- and intrasegment modulation of renal purinergic signaling by EVs. Our findings postulate EVs as carriers of information along the renal tubules, whereby processes affecting EV release and/or cargo may impact on purinergically regulated processes.

A Quantitative Pharmacology Model of Exosome-Mediated Drug Efflux and Perturbation-Induced Synergy

Exosomes, naturally occurring vesicles secreted by cells, are undergoing development as drug carriers. We used experimental and computational studies to investigate the kinetics of intracellular exosome processing and exosome-mediated drug efflux and the effects of exosome inhibition. The experiments used four human-breast or ovarian cancer cells, a cytotoxic drug paclitaxel (PTX), two exosome inhibitors (omeprazole (OME), which inhibits exosome release, and GW4869 (GW), which inhibits synthesis of sphingolipid ceramide required for exosome formation), LC-MS/MS analysis of PTX levels in exosomes, and confocal microscopic study of endocytic transport (monitored using fluorescent nanoparticles and endocytic organelle markers). In all four cells, exosome production was enhanced by PTX but diminished by OME or GW (p < 0.05); the PTX enhancement was completely reversed by OME or GW. Co-treatment with OME or GW simultaneously reduced PTX amount in exosomes and increased PTX amount and cytotoxicity in exosome-donor cells (corresponding to >2-fold synergy as indicated by curve shift and uncertainty envelope analyses). This synergy is consistent with the previous reports that OME co-administration significantly enhances the taxane activity in tumor-bearing mice and in patients with triple negative metastatic breast cancer. The experimental results were used to develop a quantitative pharmacology model; model simulations revealed the different effects of the two exosome inhibitors on intracellular PTX processing and subcellular distribution.

Roles of exosomes in diagnosis and treatment of colorectal cancer

Exosomes are extracellular vesicles that mediate intercellular communication. They contain different molecules, such as DNA, RNA, lipid, and protein, playing essential roles in the pathogenesis of colorectal cancer (CRC). Exosomes derived from CRC are implicated in tumorigenesis, chemotherapy resistance, and metastasis. Besides, they can enhance CRC progression by increasing tumor cell proliferation, reducing apoptosis mechanistically through altering particular essential regulatory genes, or controlling several signaling pathways. Therefore, exosomes derived from CRC are essential biomarkers and can be used in the diagnosis. Indeed, it is crucial to understand the role of exosomes in CRC, which is necessary to develop diagnostic and therapeutic strategies for early detection and treatment. In the present review, we discuss the roles of exosomes in the diagnosis and treatment of CRC.

Emerging role of tumor microenvironment derived exosomes in therapeutic resistance and metastasis through epithelial-to-mesenchymal transition

The tumor microenvironment (TME) constitutes multiple cell types including cancerous and non-cancerous cells. The intercellular communication between these cells through TME derived exosomes may either enhance or suppress the tumorigenic processes. The tumor-derived exosomes could convert an anti-tumor environment into a pro-tumor environment by inducing the differentiation of stromal cells into tumor-associated cells. The exosomes from tumor-associated stromal cells reciprocally trigger epithelial-to-mesenchymal transition (EMT) in tumor cells, which impose therapeutic resistance and metastasis. It is well known that these exosomes contain the signals of EMT, but how these signals execute chemoresistance and metastasis in tumors remains elusive. Understanding the significance and molecular signatures of exosomes transmitting EMT signals would aid in developing appropriate methods of inhibiting them. In this review, we focus on molecular signatures of exosomes that shuttle between cancer cells and their stromal populations in TME to explicate their impact on therapeutic resistance and metastasis through EMT. Especially Wnt signaling is found to be involved in multiple ways of exosomal transport and hence we decipher the biomolecules of Wnt signaling trafficked through exosomes and their potential in serving as therapeutic targets.

Cell-Secreted Vesicles: Novel Opportunities in Cancer Diagnosis, Monitoring and Treatment

Extracellular vesicles (EVs) are important mediators of intercellular communication playing a pivotal role in the regulation of physiological and pathological processes, including cancer. In particular, there is significant evidence suggesting that tumor-derived EVs exert an immunosuppressive activity during cancer progression, as well as stimulate tumor cell migration, angiogenesis, invasion and metastasis. The use of EVs as a liquid biopsy is currently a fast-growing area of research in medicine, with the potential to provide a step-change in the diagnosis and treatment of cancer, allowing the prediction of both therapy response and prognosis. EVs could be useful not only as biomarkers but also as drug delivery systems, and may represent a target for anticancer therapy. In this review, we attempted to summarize the current knowledge about the techniques used for the isolation of EVs and their roles in cancer biology, as liquid biopsy biomarkers and as therapeutic tools and targets.

Tumor-Derived Exosomes (TEX) and Their Role in Immuno-Oncology

Extracellular vesicles (EVs) play a key role in health and disease, including cancer. Tumors produce a mix of EVs differing in size, cellular origin, biogenesis and molecular content. Small EVs (sEV) or exosomes are a subset of 30-150 nm (virus-size) vesicles originating from the multivesicular bodies (MVBs) and carrying a cargo that in its content and topography approximates that of a parent cell. Tumor-derived exosomes (TEX) present in all body fluids of cancer patients, are considered promising candidates for a liquid tumor biopsy. TEX also mediate immunoregulatory activities: they maintain a crosstalk between the tumor and various non-malignant cells, including immunocytes. Effects that EVs exert on immune cells may be immunosuppressive or immunostimulatory. Here, we review the available data for TEX interactions with immunocytes, focusing on strategies that allow isolation from plasma and separation of TEX from sEV produced by non-malignant cells. Immune effects mediated by either of the subsets can now be distinguished and measured. The approach has allowed for the comparison of molecular and functional profiles of the two sEV fractions in plasma of cancer patients. While TEX carried an excess of immunosuppressive proteins and inhibited immune cell functions in vitro and in vivo, the sEV derived from non-malignant cells, including CD3(+)T cells, were variably enriched in immunostimulatory proteins and could promote functions of immunocytes. Thus, sEV in plasma of cancer patients are heterogenous, representing a complex molecular network which is not evident in healthy donors' plasma. Importantly, TEX appear to be able to reprogram functions of non-malignant CD3(+)T cells inducing them to produce CD3(+)sEV enriched in immunosuppressive proteins. Ratios of stimulatory/inhibitory proteins carried by TEX and by CD3(+)sEV derived from reprogrammed non-malignant cells vary broadly in patients and appear to negatively correlate with disease progression. Simultaneous capture from plasma and functional/molecular profiling of TEX and the CD3(+)sEV fractions allows for defining their role as cancer biomarkers and as monitors of cancer patients' immune competence, respectively.

Tumor innervation: peripheral nerves take control of the tumor microenvironment

In recent decades, cancer research has expanded exponentially beyond the study of abnormally dividing cells to include complex and extensive heterotypic interactions between cancer and noncancer cells that constitute the tumor microenvironment (TME). Modulation of stromal, immune, and endothelial cells by cancer cells promotes proliferation, survival, and metabolic changes that support tumor growth and metastasis. Recent evidence demonstrates that tumors can recruit peripheral nerves to the TME, leading to enhanced tumor growth in a range of cancer models through distinct mechanisms. This process, termed tumor innervation, is associated with an aggressive tumor phenotype and correlates with poor prognosis in clinical studies. Therefore, the peripheral nervous system may play an underrecognized role in cancer development, harboring targetable pathways that warrant investigation. To date, nerves have been implicated in driving proliferation, invasion, metastasis, and immune evasion through locally delivered neurotransmitters. However, emerging evidence suggests that cell-cell communication via exosomes induces tumor innervation, and thus exosomes may also mediate neural regulation of the TME. In this Review, seminal studies establishing tumor innervation are discussed, and known and putative signaling mechanisms between peripheral nerves and components of the TME are explored as a means to identify potential opportunities for therapeutic intervention.

Extracellular vesicles in immunomodulation and tumor progression

Extracellular vesicles have emerged as prominent regulators of the immune response during tumor progression. EVs contain a diverse repertoire of molecular cargo that plays a critical role in immunomodulation. Here, we identify the role of EVs as mediators of communication between cancer and immune cells. This expanded role of EVs may shed light on the mechanisms behind tumor progression and provide translational diagnostic and prognostic tools for immunologists.

Targeting regulatory T cells for immunotherapy in melanoma

Regulatory T cells (Tregs) are essential in the maintenance of immunity, and they are also a key to immune suppressive microenvironment in solid tumors. Many studies have revealed the biology of Tregs in various human pathologies. Here we review recent understandings of the immunophenotypes and suppressive functions of Tregs in melanoma, including Treg recruitment and expansion in a tumor. Tregs are frequently accumulated in melanoma and the ratio of CD8+ T cells versus Tregs in the melanoma is predictive for patient survival. Hence, depletion of Tregs is a promising strategy for the enhancement of anti-melanoma immunity. Many recent studies are aimed to target Tregs in melanoma. Distinguishing Tregs from other immune cells and understanding the function of different subsets of Tregs may contribute to better therapeutic efficacy. Depletion of functional Tregs from the tumor microenvironment has been tested to induce clinically relevant immune responses against melanomas. However, the lack of Treg specific therapeutic antibodies or Treg specific depleting strategies is a big hurdle that is yet to be overcome. Additional studies to fine-tune currently available therapies and more agents that specifically and selectively target tumor infiltrating Tregs in melanoma are urgently needed.

Leukemic extracellular vesicles induce chimeric antigen receptor T cell dysfunction in chronic lymphocytic leukemia

Chimeric antigen receptor (CAR) T cell therapy has yielded unprecedented outcomes in some patients with hematological malignancies; however, inhibition by the tumor microenvironment has prevented the broader success of CART cell therapy. We used chronic lymphocytic leukemia (CLL) as a model to investigate the interactions between the tumor microenvironment and CART cells. CLL is characterized by an immunosuppressive microenvironment, an abundance of systemic extracellular vesicles (EVs), and a relatively lower durable response rate to CART cell therapy. In this study, we characterized plasma EVs from untreated CLL patients and identified their leukemic cell origin. CLL-derived EVs were able to induce a state of CART cell dysfunction characterized by phenotypical, functional, and transcriptional changes of exhaustion. We demonstrate that, specifically, PD-L1+ CLL-derived EVs induce CART cell exhaustion. In conclusion, we identify an important mechanism of CART cell exhaustion induced by EVs from CLL patients.

Elucidating Methods for Isolation and Quantification of Exosomes: A Review

Exosomes are the smallest extracellular vesicles present in most of the biological fluids. They are found to play an important role in cell signaling, immune response, tumor metastasis, etc. Studies have shown that these vesicles also have diagnostic and therapeutic roles for which their accurate detection and quantification is essential. Due to the complexity in size and structure of exosomes, even the gold standard methods face challenges. This comprehensive review discusses the various standard methods such as ultracentrifugation, ultrafiltration, size-exclusion chromatography, precipitation, immunoaffinity, and microfluidic technologies for the isolation of exosomes. The principle of isolation of each method is described, as well as their specific advantages and disadvantages. Quantification of exosomes by nanoparticle tracking analysis, flow cytometry, tunable resistive pulse sensing, electron microscopy, dynamic light scattering, and microfluidic devices are also described, along with the applications of exosomes in various biomedical domains.

Exosomes: Small EVs with Large Immunomodulatory Effect in Glioblastoma

Glioblastomas are among the most aggressive tumors, and with low survival rates. They are characterized by the ability to create a highly immunosuppressive tumor microenvironment. Exosomes, small extracellular vesicles (EVs), mediate intercellular communication in the tumor microenvironment by transporting various biomolecules (RNA, DNA, proteins, and lipids), therefore playing a prominent role in tumor proliferation, differentiation, metastasis, and resistance to chemotherapy or radiation. Exosomes are found in all body fluids and can cross the blood-brain barrier due to their nanoscale size. Recent studies have highlighted the multiple influences of tumor-derived exosomes on immune cells. Owing to their structural and functional properties, exosomes can be an important instrument for gaining a better molecular understanding of tumors. Furthermore, they qualify not only as diagnostic and prognostic markers, but also as tools in therapies specifically targeting aggressive tumor cells, like glioblastomas.

Genetic Background and Kinetics Define Wound Bed Extracellular Vesicles in a Mouse Model of Cutaneous Injury

Extracellular vesicles (EVs) have an important role in mediating intercellular signaling in inflammation and affect the kinetics of wound healing, however, an understanding of the mechanisms regulating these responses remains limited. Therefore, we have focused on the use of cutaneous injury models in which to study the biology of EVs on the inflammatory phase of wound healing. For this, the foreign body response using sterile subcutaneous polyvinylalcohol (PVA) sponges is ideally suited for the parallel analysis of immune cells and EVs without the need for tissue dissociation, which would introduce additional variables. We have previously used this model to identify mediators of EV biogenesis, establishing that control of how EVs are made affects their payload and biological activity. These studies in normal mice led us to consider how conditions such as immunodeficiency and obsesity affect the profile of immune cells and EVs in this model using genetically defined mutant mice. Since EVs are intrinsically heterogenous in biological fluids, we have focused our studies on a novel technology, vesicle flow cytometry (vFC) to quantify changes in EVs in mouse models. Here, we show that myeloid-derived immune cells and EVs express proteins relevant in antigen presentation in PVA sponge implants that have distinct profiles in wildtype, immune-deficient (NOD scid) vs. diabetic (Leprdb) mice. Together, these results establish a foundation for the parallel analysis of both immune cells and EVs with technologies that begin to address the heterogeneity of intercellular communication in the wound bed.

Regulation of Antitumor Immune Responses by Exosomes Derived from Tumor and Immune Cells

Exosomes are lipid membrane-enclosed vesicles released by all cell types that act at the paracrine or endocrine level to favor cell differentiation, tissue homeostasis, organ remodeling and immune regulation. Their biosynthesis begins with a cell membrane invagination which generates an early endosome that matures to a late endosome. By inward budding of the late endosome membrane, a multivesicular body (MVB) with intraluminal vesicles (ILVs) is generated. The fusion of MVBs with the plasma membrane releases ILVs into the extracellular space as exosomes, ranging in size from 30 to 100 nm in diameter. The bilipid exosome membrane is rich in cholesterol, ceramides and phosphatidylserine and can be loaded with DNA, RNA, microRNAs, proteins and lipids. It has been demonstrated that exosome secretion is a common mechanism used by the tumor to generate an immunosuppressive microenvironment that favors cancer development and progression, allowing tumor escape from immune control. Due to their ability to transport proteins, lipids and nucleic acids from the cell that gave rise to them, exosomes can be used as a source of biomarkers with great potential for clinical applications in diagnostic, prognostic or therapeutic areas. This article will review the latest research findings on exosomes and their contribution to cancer development.

A Comprehensive Review on Factors Influences Biogenesis, Functions, Therapeutic and Clinical Implications of Exosomes

Exosomes are nanoscale-sized membrane vesicles secreted by almost all cell types into the extracellular environment upon fusion of multivesicular bodies and plasma membrane. Biogenesis of exosomes is a protein quality control mechanism, and once released, exosomes transmit signals to other cells. The applications of exosomes have increased immensely in biomedical fields owing to their cell-specific cargos that facilitate intercellular communications with neighboring cells through the transfer of biologically active compounds. The diverse constituents of exosomes reflect their cell of origin and their detection in biological fluids represents a diagnostic marker for various diseases. Exosome research is expanding rapidly due to the potential for clinical application to therapeutics and diagnosis. However, several aspects of exosome biology remain elusive. To discover the use of exosomes in the biomedical applications, we must better understand the basic molecular mechanisms underlying their biogenesis and function. In this comprehensive review, we describe factors involved in exosomes biogenesis and the role of exosomes in intercellular signaling and cell-cell communications, immune responses, cellular homeostasis, autophagy, and infectious diseases. In addition, we discuss the role of exosomes as diagnostic markers, and their therapeutic and clinical implications. Furthermore, we addressed the challenges and outstanding developments in exosome research, and discuss future perspectives.

The roles of extracellular vesicles in the development, microenvironment, anticancer drug resistance, and therapy of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the main malignant tumours affecting human health, mainly due to delayed diagnosis and high invasiveness. Extracellular vehicles (EVs) are membranous vesicles released by cells into the extracellular matrix that carry important signalling molecules and stably and widely exist in various body fluids, such as plasma, saliva, cerebrospinal fluid, breast milk, urine, semen, lymphatic fluid, synovial fluid, amniotic fluid, and sputum. EVs transport almost all types of bioactive molecules (DNA, mRNAs, microRNAs (miRNAs), proteins, metabolites, and even pharmacological compounds). These "cargoes" can act on recipient cells, reshaping the surrounding microenvironment and altering distant targets, ultimately affecting their biological behaviour. The extensive exploration of EVs has deepened our comprehensive understanding of HNSCC biology. In this review, we not only summarized the effect of HNSCC-derived EVs on the tumour microenvironment but also described the role of microenvironment-derived EVs in HNSCC and discussed how the "mutual dialogue" between the tumour and microenvironment mediates the growth, metastasis, angiogenesis, immune escape, and drug resistance of tumours. Finally, the clinical application of EVS in HNSCC was assessed.

Exosomes in Immune Regulation

Exosomes, small extracellular vesicles mediate intercellular communication by transferring their cargo including DNA, RNA, proteins and lipids from cell to cell. Notably, in the immune system, they have protective functions. However in cancer, exosomes acquire new, immunosuppressive properties that cause the dysregulation of immune cells and immune escape of tumor cells supporting cancer progression and metastasis. Therefore, current investigations focus on the regulation of exosome levels for immunotherapeutic interventions. In this review, we discuss the role of exosomes in immunomodulation of lymphoid and myeloid cells, and their use as immune stimulatory agents to elicit specific cytotoxic responses against the tumor.

Progress of exosomes in the diagnosis and treatment of lung cancer

The incidence and mortality of lung cancer account for first place all over the world. Lung cancer lacks early diagnostic biomarkers; lung cancer patients are usually diagnosed in both middle and advanced stages and have poor treatment outcomes. It is more important to find the first diagnostic tools for lung cancer with high specificity and sensitivity. Besides, exosomes are usually nanometer-sized bi-layered lipid vesicles formed and produced by various types of cells. As one of the main modes of intercellular communication, they can deliver multiple functional biomolecules, such as DNA, microRNAs, messenger RNA (mRNA), long non-coding RNA, and proteins, and the events as mentioned above affects different physiological processes of recipient cells. It has been reported that exosomes are involved in different types of cancer, including lung cancer. Various studies proved that exosomes are involved in multiple cancer processes such as cell proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and the tumor microenvironment in lung cancer. Tumor-derived exosomes (TEX) contain a variety of stimulatory and inhibitory factors involved in regulating immune response, which can affect the tumor microenvironment (TME) and thus participate in the formation and progression of lung cancer. This review's primary purpose to review the latest research progress of exosomes in diagnosing and treating lung cancer.

Influence of Natural Killer Cells and Natural Killer T Cells on Periodontal Disease: A Systematic Review of the Current Literature

Natural killer (NK) cells, as members of the innate immune system, and natural killer T (NKT) cells, bridging innate and adaptive immunity, play a prominent role in chronic inflammatory diseases and cancerogenesis, yet have scarcely been examined in oral diseases. Therefore, systematic research on the latest literature focusing on NK/NKT cell-mediated mechanisms in periodontal disease, including the time period 1988-2020, was carried out in MEDLINE (PubMed) using a predetermined search strategy, with a final selection of 25 studies. The results showed that NK cells tend to have rather proinflammatory influences via cytokine production, cytotoxic effects, dendritic-cell-crosstalk, and autoimmune reactions, while contrarily, NKT cell-mediated mechanisms were proinflammatory and immunoregulatory, ranging from protective effects via B-cell-regulation, specific antibody production, and the suppression of autoimmunity to destructive effects via cytokine production, dendritic-cell-crosstalk, and T-/B-cell interactions. Since NK cells seem to have a proinflammatory role in periodontitis, further research should focus on the proinflammatory and immunoregulatory properties of NKT cells in order to create, in addition to antibacterial strategies in dental inflammatory disease, novel anti-inflammatory therapeutic approaches modulating host immunity towards dental health.

Tumor-Derived Extracellular Vesicles and the Immune System-Lessons From Immune-Competent Mouse-Tumor Models

Tumor-derived extracellular vesicles (TEVs) are important regulators of the immune response in cancer; however, most research so far has been carried out using cell culture systems. Immune-competent murine tumor models currently provide the best platform to assess proposed roles of TEVs using in vivo animal models and therefore are important for examining interactions between TEVs and the immune system. In this review, we present the current knowledge on TEVs using in vivo tumor-bearing animal models, with a focus on the role of TEVs in mediating crosstalk between tumor cells and both adaptive and innate immune cells. In particular, we address the question how animal models can clarify the reported heterogeneity of TEV effects in both anti-tumor responses and evasion of immune surveillance. The potential of TEVs in mediating direct antigen-presenting functions supports their potential as cancer vaccine therapeutics, therefore, we provide an overview of key findings of TEV trials that have the potential as novel immunotherapies, and shed light on challenges in the path toward the first in-human trials. We also highlight the important updates on the methods that continue to enhance the rigor and reproducibility of EV studies, particularly in functional animal models.

Feasibility of phosphoproteomics to uncover oncogenic signalling in secreted extracellular vesicles using glioblastoma-EGFRVIII cells as a model

Cancer cells secrete extracellular vesicles (EVs) that contain molecular information, including proteins and RNA. Oncogenic signalling can be transferred via the cargo of EVs to recipient cells and may influence the behaviour of neighbouring cells or cells at a distance. This cargo may contain cancer drivers, such as EGFR, and also phosphorylated (activated) components of oncogenic signalling cascades. Till date, the cancer EV phosphoproteome has not been studied in great detail. In the present study, we used U87 and U87EGFRvIII cells as a model to explore EV oncogenic signalling components in comparison to the cellular profile. EVs were isolated using the VN96 ME-kit and subjected to LC-MS/MS based phosphoproteomics and dedicated bioinformatics. Expression of (phosphorylated)-EGFR was highly increased in EGFRvIII overexpressing cells and their secreted EVs. The increased phosphorylated proteins in both cells and EVs were associated with activated components of the EGFR-signalling cascade and included EGFR, AKT2, MAPK8, SMG1, MAP3K7, DYRK1A, RPS6KA3 and PAK4 kinases. In conclusion, EVs harbour oncogenic signalling networks including multiple activated kinases including EGFR, AKT and mTOR. SIGNIFICANCE: Extracellular vesicles (EVs) are biomarker treasure troves and are widely studied for their biomarker content in cancer. However, little research has been done on the phosphorylated protein profile within cancer EVs. In the current study, we demonstrate that EVs that are secreted by U87-EGFRvIII mutant glioblastoma cells contain high levels of oncogenic signalling networks. These networks contain multiple activated (phosphorylated) kinases, including EGFR, MAPK, AKT and mTOR.

Emerging Role of Extracellular Vesicles in Immune Regulation and Cancer Progression

Simple Summary

Accumulating evidence has reported that extracellular vesicles secreted by different tumor microenvironment cells can interfere with the host immune system. These vesicles transmit the signals in the tumor microenvironment that affect the proliferation, apoptosis, activation, and, metabolism of immune cells such as dendritic cells, T cells, macrophages, and natural killer cells, creating a pro-tumoral environment for tumor progression and survival. In this review, we summarize the recent literature on the function of extracellular vesicles derived from tumor cells and immune cells in regulating the critical processes associated with cancer progression. Besides, we also provide insights on how the extracellular vesicles are employed as diagnostic and prognostic biomarkers and drug carriers in cancer.

Abstract

The development of effective therapies for cancer treatment requires a better understanding of the tumor extracellular environment and a dynamic interaction between tumor cells, the cells of the immune system, and the tumor stroma. Increasing evidence suggests that extracellular vesicles play an important role in this interaction. Extracellular vesicles are nanometer-sized membrane-bound vesicles secreted by various types of cells that facilitate intracellular communication by transferring proteins, various lipids, and nucleic acids, especially miRNAs, between cells. Extracellular vesicles play discrete roles in the immune regulatory functions, such as antigen presentation, and activation or suppression of immune cells. Achieving therapeutic intervention through targeting of extracellular vesicles is a crucial area of research now. Thus, a deeper knowledge of exosome biology and the molecular mechanism of immune regulation is likely to provide significant insight into therapeutic intervention utilizing extracellular vesicles to combat this dreadful disease. This review describes the recent updates on immune regulation by extracellular vesicles in cancer progression and possible use in cancer therapy.

Extracellular Vesicles Derived From Colorectal Cancer Affects CD8 T Cells: An Analysis Based on Body Mass Index

Colorectal cancer (CRC) is one of the most widely diagnosed cancers worldwide. It has been shown that the body-mass index (BMI) of the patients could influence the tumor microenvironment, treatment response, and overall survival rates. Nevertheless, the mechanism on how BMI affects the tumorigenesis process, particularly the tumor microenvironment is still elusive. Herein, we postulate that extracellular vesicles (EVs) from CRC patients and non-CRC volunteers with different BMI could affect immune cells differently, in CD8 T cells particularly. We isolated the EVs from the archived serum of CRC patients with high and low BMI, as well as healthy controls with similar BMI status. The EVs were further characterized via electron microscopy, western blot and dynamic light scattering. Then, functional analysis was performed on CD8 T cells including apoptosis, cell proliferation, gene expression profiling and cytokine release upon co-incubation with the different EVs. Our results suggest that CRC-derived EVs were able to regulate the CD8 T cells. In some assays, low BMI EVs were functionally different than high BMI EVs. This study highlights the possible difference in the regulatory mechanism of cancer patients-derived EVs, especially on CD8 T cells.

Overcoming Immune Evasion in Melanoma

Melanoma is the most aggressive and dangerous form of skin cancer that develops from transformed melanocytes. It is crucial to identify melanoma at its early stages, in situ, as it is "curable" at this stage. However, after metastasis, it is difficult to treat and the five-year survival is only 25%. In recent years, a better understanding of the etiology of melanoma and its progression has made it possible for the development of targeted therapeutics, such as vemurafenib and immunotherapies, to treat advanced melanomas. In this review, we focus on the molecular mechanisms that mediate melanoma development and progression, with a special focus on the immune evasion strategies utilized by melanomas, to evade host immune surveillances. The proposed mechanism of action and the roles of immunotherapeutic agents, ipilimumab, nivolumab, pembrolizumab, and atezolizumab, adoptive T- cell therapy plus T-VEC in the treatment of advanced melanoma are discussed. In this review, we implore that a better understanding of the steps that mediate melanoma onset and progression, immune evasion strategies exploited by these tumor cells, and the identification of biomarkers to predict treatment response are critical in the design of improved strategies to improve clinical outcomes for patients with this deadly disease.

mRNA and miRNA Profiles of Exosomes from Cultured Tumor Cells Reveal Biomarkers Specific for HPV16-Positive and HPV16-Negative Head and Neck Cancer

Human papillomavirus (HPV)(+) and HPV(-) head and neck cancer (HNC) cells' interactions with the host immune system are poorly understood. Recently, we identified molecular and functional differences in exosomes produced by HPV(+) vs. HPV(-) cells, suggesting that genetic cargos of exosomes might identify novel biomarkers in HPV-related HNCs. Exosomes were isolated by size exclusion chromatography from supernatants of three HPV(+) and two HPV(-) HNC cell lines. Paired cell lysates and exosomes were analyzed for messenger RNA (mRNA) by qRT-PCR and microRNA (miR) contents by nanostring analysis. The mRNA profiles of HPV(+) vs. HPV(-) cells were distinct, with EGFR, TP53 and HSPA1A/B overexpressed in HPV(+) cells and IL6, FAS and DPP4 in HPV(-) cells. The mRNA profiles of HPV(+) or HPV(-) exosomes resembled the cargo of their parent cells. miR expression profiles in cell lysates identified 8 miRs expressed in HPV(-) cells vs. 14 miRs in HPV(+) cells. miR-205-5p was exclusively expressed in HPV(+) exosomes, and miR-1972 was only detected in HPV(-) exosomes. We showed that HPV(+) and HPV(-) exosomes recapitulated the mRNA expression profiles of their parent cells. Expression of miRs was dependent on the HPV status, and miR-205-5p in HPV(+) and miR-1972 in HPV(-) exosomes emerge as potential discriminating HPV-associated biomarkers.

Extracellular vesicles in cancer progression: are they part of the problem or part of the solution?

Extracellular vesicles (EVs) are released especially by cancer cells. They modulate the tumor microenvironment by interacting with immune cells while carrying immunosuppressive or immunostimulatory molecules. In this review, we will explore some conflicting reports regarding the immunological outcomes of EVs in cancer progression, in which they might initiate an antitumor immune response or an immunosuppressive response. Concerning immunosuppression, the role of tumor-derived EVs' in the adenosinergic system is underexplored. The enhancement of adenosine (ADO) levels in the tumor microenvironment impairs T-cell function and cytokine release. However, some tumor-derived EVs may deliver immunostimulatory factors, promoting immunogenic activity, even with ADO production. The modulatory role of ADO over the tumor progression represents a piece in an intricate microenvironment with anti and pro tumoral seesaw-like mechanisms.

Exosomal PD-L1 and N-cadherin predict pulmonary metastasis progression for osteosarcoma patients

BACKGROUND

Recent studies indicated that exosomal programmed death-ligand 1 (PD-L1) derived from cancers could induce immunosuppression and tumor pathogenesis. However, it is unclear how exosomes influence osteosarcoma (OS) progression and whether PD-L1 also exists in serum exosomes (Sr-exosomes) of patients with osteosarcoma. We examined serum exosomes from 70 OS patients, 9 patients with benign tumors and 22 healthy donors. OS-derived exosomes were functionally evaluated in vivo and in vitro.

RESULTS

The characteristics of exosomes derived from OS patient serum and OS cell lines were confirmed by several methods. We found OS patients had a higher level of exosomal PD-L1 compared to healthy donors. Meanwhile, OS patients with pulmonary metastasis also showed a relatively higher level of exosomal PD-L1 than patients without metastasis. Next, bioinformatic analysis demonstrated that Sr-exosomes isolated from OS patients may involve in the important process of immune function and cancer pathogenesis for OS patients. Co-expression network centered with PD-L1 among Sr-exosomal differently expressed mRNA demonstrated exosomal N-cadherin had a close relationship with exosomal PD-L1 expression. Then, we confirmed higher level of Sr-exosomal N-cadherin in OS patients with pulmonary metastasis compared to ones without metastasis. Furthermore, we elucidated osteosarcoma-derived exosomes and exosomal-PD-L1 promoted the pulmonary metastasis in metastatic models. ROC (Receiver Operating Characteristic Curve) analysis showed AUC (Area Under Curve) of 0.823 for exosomal PD-L1, 0.806 for exosomal N-cadherin and 0.817 for exosomal N-cadherin/E-cadherin to distinguish OS patients with pulmonary metastasis from ones without metastasis.

CONCLUSIONS

Osteosarcoma stimulates pulmonary metastasis by releasing exosomes, that carry PD-L1 and N-cadherin. Detection of exosomal PD-L1 and N-cadherin from serum of OS patients may predict pulmonary metastasis progression for OS patients.

Implications of CD39 in immune-related diseases

Extracellular adenosine triphosphate (eATP) mediates pro-inflammatory responses by recruiting and activating inflammatory cells. CD39 can hydrolyze eATP into adenosine monophosphate (AMP), while CD73 can convert AMP into the immunosuppressive nucleoside adenosine (ADO). CD39 is a rate-limiting enzyme in this cascade, which is regarded as an immunological switch shifting the ATP-mediated pro-inflammatory environment to the ADO- mediated anti-inflammatory status. The CD39 expression can be detected in a wide spectrum of immunocytes, which is under the influence of environmental and genetic factors. It is increasingly suggested that, CD39 participates in some pathophysiological processes, like inflammatory bowel disease (IBD), sepsis, multiple sclerosis (MS), allergic diseases, ischemia-reperfusion (I/R) injury, systemic lupus erythematosus (SLE), diabetes and cancer. Here, we focus on the current understanding of CD39 in immunity, and comprehensively illustrate the diverse CD39 functions within a variety of disorders.

Exosomes Represent an Immune Suppressive T Cell Checkpoint in Human Chronic Inflammatory Microenvironments

Background: T cells present in chronic inflammatory tissues such as nasal polyps (from chronic rhinosinusitis patients) have been demonstrated to be hypo-responsive to activation via the TCR, similar to tumor-specific T cells in multiple different human tumor microenvironments. While immunosuppressive exosomes have been known to contribute to the failure of the tumor-associated T cells to respond optimally to activation stimuli, it is not known whether they play a similar role in chronic inflammatory microenvironments. In the current study, we investigate whether exosomes derived from chronic inflammatory microenvironments contribute to the immune suppression of T cells. Methods: Exosomes were isolated by ultracentrifugation and characterized by size and composition using nanoparticle tracking analysis, scanning electron microscopy, antibody arrays and flow exometry. Immunosuppressive ability of the exosomes was measured by quantifying its effect on activation of T cells, using nuclear translocation of NFκB as an activation endpoint. Results: Exosomes were isolated and characterized from two different types of chronic inflammatory tissues - nasal polyps from chronic rhinosinusitis patients and synovial fluid from rheumatoid arthritis patients. These exosomes arrest the activation of T cells stimulated via the TCR. This immune suppression, like that which is seen in tumor microenvironments, is dependent in part upon a lipid, ganglioside GD3, which is expressed on the exosomal surface. Conclusion: Immunosuppressive exosomes present in non-malignant chronic inflammatory tissues represent a new T cell checkpoint, and potentially represent a novel therapeutic target to enhance the response to current therapies and prevent disease recurrences.

Correlation of tumor-infiltrating immune cells of melanoma with overall survival by immunogenomic analysis

AIMS

Different types of tumor-infiltrating immune cells not only augment but also dampen antitumor immunity in the microenvironment of melanoma. Therefore, it is critical to provide an overview of tumor-infiltrating immune cells in melanoma and explore a novel strategy for immunotherapies.

METHODS

We analyzed the immune states of different stages in melanoma patients by the immune, stromal, and estimation of stromal and immune cells in malignant tumor tissues using expression data (ESTIMATE) scores. Immune cell types were identified by the estimating relative subsets of RNA transcripts (CIBERSORTx) algorithm in 471 melanoma and 324 healthy tissues. Moreover, we performed a gene set variation analysis (GSVA) to determine the differentially regulated pathways in the tumor microenvironment.

RESULTS

In melanoma cohorts, we found that ESTIMATE and immune scores were involved in survival or tumor clinical stage. Among the 22 immune cells, CD8⁺ T cells, M2 macrophages, and regulatory T cells (Tregs) showed significant differences using the CIBERSORTx algorithm. Furthermore, GSVA identified the immune cell-related pathways; the primary immunodeficiency pathway, intestinal immune network for IgA, and TGF-β pathways were identified as participants of the crosstalk in CD8⁺ T cells, Tregs, and M2 macrophages in the melanoma microenvironment.

CONCLUSION

These results reveal the cellular and molecular characteristics of immune cells in melanoma, providing a method for selecting targets of immunotherapies and promoting the efficacy of therapies for the treatment of melanoma.

Immune suppressed tumor microenvironment by exosomes derived from gastric cancer cells via modulating immune functions

Gastric cancer is one of the leading causes of cancer-related death due to late diagnosis with high metastatic frequency. In this study, the impact of tumor secreted exosomes on immune function in the tumor environment was investigated using exosomes isolated from gastric cancer cell lines MKN-28, MKN-45, and SGC-7901. Results show that exosomes derived from all of these cell lines changed the gene expression and cytokine secretion levels of CD8⁺ T cells. They also block cell cycle progression, induced apoptosis in CD8⁺ T cells. Image analysis of fluorescent labeled exosomes derived from three cell lines injected systemically into C57BL/6 mice revealed these exosomes primarily localize to the lungs. We further showed exosomes were mainly taken up by natural killer cells and macrophages in the lung. After long-term exposure to inject exosomes from MKN-45 cells, mice developed an immunosuppressive tumor microenvironment in the lung with increased frequency of effector memory CD4⁺ T and MDSC, decreased CD8⁺ T cell and NK frequency. This immune suppressive environment promotes gastric cancer lung metastasis. Lung metastasis sites developed after mice were exposed to exosomes isolated from all three gastric cancer cell lines when the mice were injected with MFC cells. Results suggest that exosomes derived from gastric cancer cells (especially MKN-45 and MKN-28) changed CD8⁺ T cell gene expression and cytokine secretion patterns to create an immunosuppressive condition for metastatic niche formation in the lung. Overall, this study provides new insights into how gastric cancer derived exosomes modulate the immune response to promote lung tumor metastasis.

The potential role of tumor-derived exosomes in diagnosis, prognosis, and response to therapy in cancer

INTRODUCTION

Small extracellular vesicles (sEV) produced by tumors and called TEX mediate communication and regulate the tumor microenvironment. As a 'liquid tumor biopsy' and with the ability to induce pro-tumor reprogramming, TEX offer a promising approach to monitoring cancer progression or response to therapy.

AREAS COVERED

TEX isolation from body fluids and separation by immunoaffinity capture from other EVs enables TEX molecular and functional characterization in vitro and in vivo. TEX carry membrane-bound PD-L1 and a rich cargo of other proteins and nucleic acids that reflect the tumor content and activity. TEX transfer this cargo to recipient cells, activating various molecular pathways and inducing pro-tumor transcriptional changes. TEX may interfere with immune therapies, and TEX plasma levels correlate with patients' responses to therapy. TEX induce local and systemic alterations in immune cells which may have a prognostic value.

EXPERT OPINION

TEX have a special advantage as potential cancer biomarkers. Their cargo emerges as a correlate of developing or progressing malignant disease; their phenotype mimics that of the tumor; and their functional reprogramming of immune cells provides a reading of the patients' immune status prior and post immunotherapy. Validation of TEX and T-cell-derived sEV as cancer biomarkers is an impending future task.

Infectious Tolerance as Seen With 2020 Vision: The Role of IL-35 and Extracellular Vesicles

Originally identified as lymphocyte regulation of fellow lymphocytes, our understanding of infectious tolerance has undergone significant evolutions in understanding since being proposed in the early 1970s by Gershon and Kondo and expanded upon by Herman Waldman two decades later. The evolution of our understanding of infectious tolerance has coincided with significant cellular and humoral discoveries. The early studies leading to the isolation and identification of Regulatory T cells (Tregs) and cytokines including TGFβ and IL-10 in the control of peripheral tolerance was a paradigm shift in our understanding of infectious tolerance. More recently, another potential, paradigm shift in our understanding of the "infectious" aspect of infectious tolerance was proposed, identifying extracellular vesicles (EVs) as a mechanism for propagating infectious tolerance. In this review, we will outline the history of infectious tolerance, focusing on a potential EV mechanism for infectious tolerance and a novel, EV-associated form for the cytokine IL-35, ideally suited to the task of propagating tolerance by "infecting" other lymphocytes.

Evaluation of Exosome Proteins by on-Bead Flow Cytometry

Exosomes, recently re-named "small extracellular vesicles" or "sEV," are emerging as an intercellular communication system. Quantification of the molecular cargo exosomes carry by on-bead flow cytometry is needed for defining their role in information transfer and in human disease. Exosomes (sEV) isolated from cell supernatants or plasma of cancer patients by size-exclusion chromatography were captured by biotinylated antibodies specific for antigens in the exosome cargo (e.g., tetraspanins) and placed on streptavidin-labeled beads. Detection was performed with pretitered fluorochrome-labeled antibodies of desired specificity. The data were acquired in a conventional cytometer, and molecules of equivalent soluble fluorochrome (MESF) beads were used to quantify the number of fluorescent molecules bound per bead. Isotype antibody controls were obligatory. The mean fluorescence intensity (MFI) value of each sample was converted into MESF units, and the separation index (SI), which quantifies separation of stained and isotype control beads, was determined. Various proteins identified by labeled antibodies were quantified on the surface of tumor cell-derived exosomes. To identify intravesicular cargo, such as cytokines or chemokines, exosomes were lysed with 0.3% Triton-100, and the proteins in lysates were loaded on aldehyde/sulfate latex beads for flow cytometry. Examples of quantitative surface and/or intravesicular on-bead flow cytometry for exosomes produced by various cells or present in body fluids of cancer patients are provided. On-bead flow cytometry standardized for use with conventional cytometers is a useful method for protein detection and quantitation in exosomes isolated from supernatants of cell lines or plasma of patients with cancer. © 2020 International Society for Advancement of Cytometry.

Advances of exosome isolation techniques in lung cancer

Lung cancer (LC) is among the leading causes of death all over the world and it is often diagnosed at advanced or metastatic stages. Exosomes, derived from circulating vesicles that are released from the multivesicular body, can be utilized for diagnosis and also the prognosis of LC at early stages. Exosomal proteins, RNAs, and DNAs can help to better discern the prognostic and diagnostic features of LC. To our knowledge, there are various reviews on LC and the contribution of exosomes, but none of them are about the exome techniques and also their efficiency in LC. To fill this gap, in this review, we summarize the recent investigations regarding isolation and also the characterization of exosomes of LC cells. Furthermore, we discuss the noncoding RNAs as biomarkers and their applications in the diagnosis and prognosis of LC. Finally, we compare the efficacy of exosome isolation methods to better fi + 6 + guring out feasible techniques.

Involvement of MM cell-derived exosomes in T lymphocytes immune responses

Exosomes were reported to mediate cell communication in the tumor microenvironment; however, the effects of multiple myeloma (MM)-derived exosomes on the quantity and function of T cells remain unknown. Exosomes were extracted from MM cell lines (OPM2 and U266B1) by ultracentrifugation using a Total Exosome Isolation kit. Exosomes were co-cultured with CD4+ T, CD8+ T and regulatory T (Treg) cells that were isolated from healthy donors (HDs) and patients with MM using magnetic beads. Flow cytometry was used to detect T cells apoptosis and expression of perforin and granzyme B in CD8+ T cells. Cell viability was detected using Cell Counting kit-8, and interleukin 10 (IL-10) and transforming growth factor β (TGF-β) in cell supernatants were detected by ELISA. The apoptosis of HD-CD4+ T was higher in the OPM2 group, and viability in the U266B1 group was decreased. The apoptosis of HD-CD8+ T decreased in the OPM2 and U266B1 groups, and cell viability increased in the OPM2 and the U266B1 groups. Perforin of HD-CD8+ T in the U266B1 group was lower while perforin of MM-CD8+ T in OPM2 and U266B1 groups was markedly decreased. The apoptosis of HD-Treg was lower in the U266B1 group, but apoptosis of MM-Treg was higher in the U266B1 group. The viability of HD-Treg in U266B1 group increased but the viability of MM-Treg in OPM2 and U266B1 groups decreased. TGF-β from MM-Treg decreased in the OPM2 and U266B1 groups when compared with the control group (P<0.05). MM-derived exosomes promote apoptosis and inhibit proliferation of HD-CD4+ T, inhibit apoptosis and promote proliferation, but inhibit perforin of HD-CD8+ T, inhibit apoptosis and promote proliferation HD-Treg, and inhibit perforin of MM-CD8+ T and TGF-β secretion of MM-Treg.

Exosomes: key players in cancer and potential therapeutic strategy

Exosomes are extracellular vesicles secreted by most eukaryotic cells and participate in intercellular communication. The components of exosomes, including proteins, DNA, mRNA, microRNA, long noncoding RNA, circular RNA, etc., which play a crucial role in regulating tumor growth, metastasis, and angiogenesis in the process of cancer development, and can be used as a prognostic marker and/or grading basis for tumor patients. Hereby, we mainly summarized as followed: the role of exosome contents in cancer, focusing on proteins and noncoding RNA; the interaction between exosomes and tumor microenvironment; the mechanisms that epithelial-mesenchymal transition, invasion and migration of tumor affected by exosomes; and tumor suppression strategies based on exosomes. Finally, the application potential of exosomes in clinical tumor diagnosis and therapy is prospected, which providing theoretical supports for using exosomes to serve precise tumor treatment in the clinic.

FcεRI Signaling in the Modulation of Allergic Response: Role of Mast Cell-Derived Exosomes

Mast cells (MCs) are immune cells that act as environment resident sentinels playing a crucial role in Th2-mediated immune responses, including allergic reactions. Distinguishing features of MCs are the presence of numerous cytoplasmic granules that encapsulate a wide array of preformed bio-active molecules and the constitutive expression of the high affinity receptor of IgE (FcεRI). Upon FcεRI engagement by means of IgE and multivalent antigens, aggregated receptors trigger biochemical pathways that ultimately lead to the release of granule-stored and newly synthesized pro-inflammatory mediators. Additionally, MCs are also able to release exosomes either constitutively or upon stimulation. Exosomes are nanosized vesicles of endocytic origin endowed with important immunoregulatory properties, and represent an additional way of intercellular communication. Interestingly, exosomes generated upon FcεRI engagement contain co-stimulatory and adhesion molecules, lipid mediators, and MC-specific proteases, as well as receptor subunits together with IgE and antigens. These findings support the notion that FcεRI signaling plays an important role in influencing the composition and functions of exosomes derived by MCs depending on their activation status.