Exosomes Associated with Human Ovarian Tumors Harbor a Reversible Checkpoint of T-cell Responses

Tumor-derived exosomal PD-L1: a new perspective in PD-1/PD-L1 therapy for lung cancer

Exosomes play a crucial role in facilitating intercellular communication within organisms. Emerging evidence indicates that a distinct variant of programmed cell death ligand-1 (PD-L1), found on the surface of exosomes, may be responsible for orchestrating systemic immunosuppression that counteracts the efficacy of anti-programmed death-1 (PD-1) checkpoint therapy. Specifically, the presence of PD-L1 on exosomes enables them to selectively target PD-1 on the surface of CD8+ T cells, leading to T cell apoptosis and impeding T cell activation or proliferation. This mechanism allows tumor cells to evade immune pressure during the effector stage. Furthermore, the quantification of exosomal PD-L1 has the potential to serve as an indicator of the dynamic interplay between tumors and immune cells, thereby suggesting the promising utility of exosomes as biomarkers for both cancer diagnosis and PD-1/PD-L1 inhibitor therapy. The emergence of exosomal PD-L1 inhibitors as a viable approach for anti-tumor treatment has garnered significant attention. Depleting exosomal PD-L1 may serve as an effective adjunct therapy to mitigate systemic immunosuppression. This review aims to elucidate recent insights into the role of exosomal PD-L1 in the field of immune oncology, emphasizing its potential as a diagnostic, prognostic, and therapeutic tool in lung cancer.

Bruton's tyrosine kinase-bearing B cells and microglia in neuromyelitis optica spectrum disorder

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory autoimmune disease of the central nervous system that involves B-cell receptor signaling as well as astrocyte-microglia interaction, which both contribute to evolution of NMOSD lesions.

MAIN BODY

Through transcriptomic and flow cytometry analyses, we found that Bruton's tyrosine kinase (BTK), a crucial protein of B-cell receptor was upregulated both in the blood and cerebrospinal fluid of NMOSD patients. Blockade of BTK with zanubrutinib, a highly specific BTK inhibitor, mitigated the activation and maturation of B cells and reduced production of causal aquaporin-4 (AQP4) autoantibodies. In a mouse model of NMO, we found that both BTK and pBTK expression were significantly increased in microglia. Transmission electron microscope scan demonstrated that BTK inhibitor ameliorated demyelination, edema, and axonal injury in NMO mice. In the same mice colocalization of GFAP and Iba-1 immunofluorescence indicated a noticeable increase of astrocytes-microglia interaction, which was alleviated by zanubrutinib. The smart-seq analysis demonstrated that treatment with BTK inhibitor instigated microglial transcriptome changes including downregulation of chemokine-related genes and genes involved in the top 5 biological processes related to cell adhesion and migration, which are likely responsible for the reduced crosstalk of microglia and astrocytes.

CONCLUSIONS

Our results show that BTK activity is enhanced both in B cells and microglia and BTK inhibition contributes to the amelioration of NMOSD pathology. These data collectively reveal the mechanism of action of BTK inhibition and corroborate BTK as a viable therapeutic target.

Canine diffuse large b-cell lymphoma downregulates the activity of CD8 + T-cells through tumor-derived extracellular vesicles

BACKGROUND

Tumor-derived extracellular vesicles (EVs) have been proposed as the essential mediator between host immunity and cancer development. These EVs conduct cellular communication to facilitate tumor growth, enable invasion and metastasis, and shape the favorable tumor microenvironment. Lymphoma is one of the most common hematological malignancies in humans and dogs. Effective T-cell responses are required for the control of these malignancies. However, the immune crosstalk between CD8 + T-cells, which dominates anti-tumor responses, and canine lymphoma has rarely been described.

METHODS

This study investigates the immune manipulating effects of EVs, produced from the clinical cases and cell line of canine B cell lymphoma, on CD8 + T-cells isolated from canine donors.

RESULTS

Lymphoma-derived EVs lead to the apoptosis of CD8 + T-cells. Furthermore, EVs trigger the overexpression of CTLA-4 on CD8 + T-cells, which indicates that EV blockade could serve as a potential therapeutic strategy for lymphoma patients. Notably, EVs transform the CD8 + T-cells into regulatory phenotypes by upregulating their PD-1, PD-L1, and FoxP3 mRNA expression. The regulatory CD8 + T-cells secret the panel of inhibitory cytokines and angiogenic factors and thus create a pro-tumorigenic microenvironment.

CONCLUSION

In summary, the current study demonstrated that the EVs derived from canine B cell lymphoma impaired the anti-tumor activity of CD8 + T-cells and manipulated the possible induction of regulatory CD8 + T-cells to fail the activation of host cellular immunity.

Unlocking Exosome-Based Theragnostic Signatures: Deciphering Secrets of Ovarian Cancer Metastasis

Ovarian cancer (OC) is a common gynecological cancer worldwide. Unfortunately, the lack of early detection methods translates into a substantial cohort of women grappling with the pressing health crisis. The discovery of extracellular vesicles (EVs) (their major subpopulation exosomes, microvesicles, and apoptotic bodies) has provided new insights into the understanding of cancer. Exosomes, a subpopulation of EVs, play a crucial role in cellular communication and reflect the cellular status under both healthy and pathological conditions. Tumor-derived exosomes (TEXs) dynamically influence ovarian cancer progression by regulating uncontrolled cell growth, immune suppression, angiogenesis, metastasis, and the development of drug and therapeutic resistance. In the field of OC diagnostics, TEXs offer potential biomarkers in various body fluids. On the other hand, exosomes have also shown promising abilities to cure ovarian cancer. In this review, we address the interlink between exosomes and ovarian cancer and explore their theragnostic signature. Finally, we highlight future directions of exosome-based ovarian cancer research.

The diagnostic and therapeutic prospects of exosomes in ovarian cancer

Exosomes are nano-sized vesicles derived from the endosomal system and are involved in many biological and pathological processes. Emerging evidence has demonstrated that exosomes with cell-specific constituents are associated with the tumorigenesis and progression of ovarian cancer. Therefore, exosomes derived from ovarian cancers can be potential diagnostic biomarkers and therapeutic targets. In this review, we briefly present the biological characteristics of exosomes and the recent advances in isolating and detecting exosomes. Furthermore, we summarise the many functions of exosomes in ovarian cancer, hoping to provide a theoretical basis for clinical applications of exosomes in the diagnosis and treatment of ovarian cancer.

Clinical Application of Small Extracellular Vesicles in Gynecologic Malignancy Treatments

Small extracellular vesicles (sEVs) are the key mediators of intercellular communication. They have the potential for clinical use as diagnostic or therapeutic biomarkers and have been explored as vectors for drug delivery. Identification of reliable and noninvasive biomarkers, such as sEVs, is important for early diagnosis and precise treatment of gynecologic diseases to improve patient prognosis. Previous reviews have summarized routine sEVs isolation and identification methods; however, novel and unconventional methods have not been comprehensively described. This review summarizes a convenient method of isolating sEVs from body fluids and liquid biopsy-related sEV markers for early, minimally invasive diagnosis of gynecologic diseases. In addition, the characteristics of sEVs as drug carriers and in precision treatment and drug resistance are introduced, providing a strong foundation for identifying novel and potential therapeutic targets for sEV therapy. We propose potential directions for further research on the applications of sEVs in the diagnosis and treatment of gynecologic diseases.

Immune determinants of the pre-metastatic niche

Primary tumors actively and specifically prime pre-metastatic niches (PMNs), the future sites of organotropic metastasis, preparing these distant microenvironments for disseminated tumor cell arrival. While initial studies of the PMN focused on extracellular matrix alterations and stromal reprogramming, it is increasingly clear that the far-reaching effects of tumors are in great part achieved through systemic and local PMN immunosuppression. Here, we discuss recent advances in our understanding of the tumor immune microenvironment and provide a comprehensive overview of the immune determinants of the PMN's spatiotemporal evolution. Moreover, we depict the PMN immune landscape, based on functional pre-clinical studies as well as mounting clinical evidence, and the dynamic, reciprocal crosstalk with systemic changes imposed by cancer progression. Finally, we outline emerging therapeutic approaches that alter the dynamics of the interactions driving PMN formation and reverse immunosuppression programs in the PMN ensuring early anti-tumor immune responses.

Neutrophil interactions with T cells, platelets, endothelial cells, and of course tumor cells

Neutrophils sense microbes and host inflammatory mediators, and traffic to sites of infection where they direct a broad armamentarium of antimicrobial products against pathogens. Neutrophils are also activated by damage-associated molecular patterns (DAMPs), which are products of cellular injury that stimulate the innate immune system through pathways that are similar to those activated by microbes. Neutrophils and platelets become activated by injury, and cluster and cross-signal to each other with the cumulative effect of driving antimicrobial defense and hemostasis. In addition, neutrophil extracellular traps are extracellular chromatin and granular constituents that are generated in response to microbial and damage motifs and are pro-thrombotic and injurious. Although neutrophils can worsen tissue injury, neutrophils may also have a role in facilitating wound repair following injury. A central theme of this review relates to how critical functions of neutrophils that evolved to respond to infection and damage modulate the tumor microenvironment (TME) in ways that can promote or limit tumor progression. Neutrophils are reprogrammed by the TME, and, in turn, can cross-signal to tumor cells and reshape the immune landscape of tumors. Importantly, promising new therapeutic strategies have been developed to target neutrophil recruitment and function to make cancer immunotherapy more effective.

The role of interferons in ovarian cancer progression: Hinderer or promoter?

Ovarian cancer (OC) is a common gynecologic malignancy with poor prognosis and high mortality. Changes in the OC microenvironment are closely related to the genesis, invasion, metastasis, recurrence, and drug-resistance. The OC microenvironment is regulated by Interferons (IFNs) known as a type of important cytokines. IFNs have a bidirectional regulation for OC cells growth and survival. Meanwhile, IFNs positively regulate the recruitment, differentiation and activation of immune cells. This review summarizes the secretion and the role of IFNs. In particular, we mainly elucidate the actions played by IFNs in various types of therapy. IFNs assist radiotherapy, targeted therapy, immunotherapy and biotherapy for OC, except for some IFN pathways that may cause chemo-resistance. In addition, we present some advances in OC treatment with the help of IFN pathways. IFNs have the ability to powerfully modulate the tumor microenvironment and can potentially provide new combination strategies for OC treatment.

Extracellular Vesicles and Their Roles in the Tumor Immune Microenvironment

Tumor cells actively incorporate molecules (e.g., proteins, lipids, RNA) into particles named extracellular vesicles (EVs). Several groups have demonstrated that EVs can be transferred to target (recipient) cells, making EVs an important means of intercellular communication. Indeed, EVs are able to modulate the functions of target cells by reprogramming signaling pathways. In a cancer context, EVs promote the formation of a supportive tumor microenvironment (TME) and (pre)metastatic niches. Recent studies have revealed that immune cells, tumor cells and their secretome, including EVs, promote changes in the TME and immunosuppressive functions of immune cells (e.g., natural killer, dendritic cells, T and B cells, monocytes, macrophages) that allow tumor cells to establish and propagate. Despite the growing knowledge on EVs and on their roles in cancer and as modulators of the immune response/escape, the translation into clinical practice remains in its early stages, hence requiring improved translational research in the EVs field. Here, we comprehensively review the current knowledge and most recent research on the roles of EVs in tumor immune evasion and immunosuppression in both solid tumors and hematological malignancies. We also highlight the clinical utility of EV-mediated immunosuppression targeting and EV-engineering. Importantly, we discuss the controversial role of EVs in cancer biology, current limitations and future perspectives to further the EV knowledge into clinical practice.

Exosomes carrying immune checkpoints, a promising therapeutic approach in cancer treatment

Exosomes are a subgroup of extracellular vesicles generated by distinct cells. Tumor-derived extracellular vesicles convey immunological checkpoint molecules. TEXs as critical mediators in tumor development, metastasis, and immune escape have recently become the focus of scientific research. Exosomes are involved in the regulation of the immune system. Exosomes interact with target cells in the tumor microenvironment, changing their function based on the cargo they contain. Exosomal immune checkpoints might be exploited to track tumor immune evasion, treatment response, and patient prognosis while enhancing tumor cell proliferation and spread. This review focuses on tumor-derived exosomes, their immunosuppressive effects in mice models, and their role in cancer immunotherapy. Exosomes are being studied as possible cancer vaccines, with numerous uses in tumor immunotherapy. Exosomes can carry chemotherapeutics, siRNA, and monoclonal antibodies. Exosomes produced by macrophages might be used to treat cancer. These and other clinical consequences provide new doors for cancer treatment.

Tumor-derived exosomes in the cancer immune microenvironment and cancer immunotherapy

Tumor-derived exosomes (TDEs) are key immune regulators in the tumor microenvironment. They have been shown to reshape the immune microenvironment and prevent antitumor immune responses via their immunosuppressive cargo, thereby determining responsiveness to cancer therapy. By delivering suppressive cargo to the immune cells, TDEs directly or indirectly influence the functions and antitumor activities of immune cells. TDE-based therapy is emerging as a cutting-edge and promising strategy for inhibiting tumor progression or enhancing antitumor immunity. Therefore, in this study, we reviewed the mechanism by which TDEs regulate immune cells and their applications in immunotherapy.

Immunosuppressive Extracellular Vesicles as a Linking Factor in the Development of Tumor and Endometriotic Lesions in the Gynecologic Tract

Both gynecological tumors and endometriosis require for their development a favorable environment, termed in the case of tumors a "pre-metastatic niche" and in case of endometriosis a "pro-endometriotic niche". This is characterized by chronic inflammation and immunosuppression that support the further progression of initial lesions. This microenvironment is established and shaped in the course of a vivid cross-talk between the tumor or endometrial cells with other stromal, endothelial and immune cells. There is emerging evidence that extracellular vesicles (EVs) play a key role in this cellular communication, mediating both in tumors and endometriosis similar immunosuppressive and pro-inflammatory mechanisms. In this review, we discuss the latest findings about EVs as immunosuppressive factors, highlighting the parallels between gynecological tumors and endometriosis. Furthermore, we outline their role as potential diagnostic or prognostic biomarkers as well as their future in therapeutic applications.

Extracellular vesicles in ovarian cancer chemoresistance, metastasis, and immune evasion

Chemoresistance and metastasis are the major challenges for the current ovarian cancer treatment. Understanding the mechanisms of ovarian cancer progression and metastasis is critically important for developing novel therapies. The advances in extracellular vesicles (EVs) research in recent years have attracted extensive attention. EVs contain a variety of proteins, RNAs, DNAs, and metabolites. Accumulating evidence indicates that ovarian cancer cells secrete a large amount of EVs, playing an important role in tumor progression and recurrence. In the microenvironment of ovarian tumor, EVs participate in the information transmission between stromal cells and immune cells, promoting the immune escape of ovarian cancer cells and facilitating cancer metastasis. Here, we review the recent advances of EVs in chemoresistance, mechanisms of metastasis, and immune evasion of ovarian cancer. Furthermore, we also discuss the challenges of EV research and future application of EVs as promising biomarker sources in response to therapy and in therapy-delivery approaches for ovarian cancer patients.

Anti-Cancer Role and Therapeutic Potential of Extracellular Vesicles

Cell-cell communication is an important mechanism in biological processes. Extracellular vesicles (EVs), also referred to as exosomes, microvesicles, and prostasomes, are microvesicles secreted by a variety of cells. EVs are nanometer-scale vesicles composed of a lipid bilayer and contain biological functional molecules, such as microRNAs (miRNAs), mRNAs, and proteins. In this review, "EVs" is used as a comprehensive term for vesicles that are secreted from cells. EV research has been developing over the last four decades. Many studies have suggested that EVs play a crucial role in cell-cell communication. Importantly, EVs contribute to cancer malignancy mechanisms such as carcinogenesis, proliferation, angiogenesis, metastasis, and escape from the immune system. EVs derived from cancer cells and their microenvironments are diverse, change in nature depending on the condition. As EVs are thought to be secreted into body fluids, they have the potential to serve as diagnostic markers for liquid biopsy. In addition, cells can encapsulate functional molecules in EVs. Hence, the characteristics of EVs make them suitable for use in drug delivery systems and novel cancer treatments. In this review, the potential of EVs as anti-cancer therapeutics is discussed.

Plasma Exosomes of Patients with Breast and Ovarian Tumors Contain an Inactive 20S Proteasome

Exosomes are directly involved in governing of physiological and pathological conditions of an organism through the transfer of information from producing to receiving cells. It can be assumed that exosomes are one of the key players of tumor dissemination since they are very stable and small enough to penetrate from various tissues into biological fluids and then back, thus interacting with tissue target cells. We evaluated the enzymatic activity and the level of 20S proteasome in tissue and exosomes of healthy females (n = 39) and patients with ovarian (n = 50) and breast (n = 108) tumors to reveal the critical role of exosomal cargo in the mediation of different types of metastases. Exosomes from plasma and ascites were isolated and characterized in according to International Society for Extracellular Vesicles guidelines. The level of 20S proteasome in tissue and exosomes was determined using Western blot analysis. Chymotrypsin- and caspase-like (ChTL and CL, respectively) peptidase activities of the proteasomes were determined using fluorogenic Suc-LLVY-AMC and Cbz-LLG-AMC substrates, respectively. We observed increased levels of 20S proteasome in ovarian cancer tissue and luminal B subtype breast cancer tissue as well as in plasma exosomes from cancer patients. Moreover, the level of the 20S proteasome in plasma exosomes and ascites exosomes in patients with ovarian tumors is comparable and higher in ovarian cancer patients with low volume ascites than in patients with moderate and high-volume ascites. We also found increased ChTL and CL activities in breast cancer and ovarian cancer tissues, as well as in peritoneal metastases in ovarian cancer, while proteasomal activity in exosomes from plasma of healthy females and all patients, as well as from ascites of ovarian tumor patients were lower than detection limit of assay. Thus, regardless of the type of tumor metastasis (lymphogenous or peritoneal), the exosomes of cancer patients were characterized by an increased level of 20S proteasome, which do not exhibit enzymatic activity.

Tumor-Associated Exosomes: A Potential Therapeutic Target for Restoring Anti-Tumor T Cell Responses in Human Tumor Microenvironments

Exosomes are a subset of extracellular vesicles (EVs) that are released by cells and play a variety of physiological roles including regulation of the immune system. Exosomes are heterogeneous and present in vast numbers in tumor microenvironments. A large subset of these vesicles has been demonstrated to be immunosuppressive. In this review, we focus on the suppression of T cell function by exosomes in human tumor microenvironments. We start with a brief introduction to exosomes, with emphasis on their biogenesis, isolation and characterization. Next, we discuss the immunosuppressive effect of exosomes on T cells, reviewing in vitro studies demonstrating the role of different proteins, nucleic acids and lipids known to be associated with exosome-mediated suppression of T cell function. Here, we also discuss initial proof-of-principle studies that established the potential for rescuing T cell function by blocking or targeting exosomes. In the final section, we review different in vivo models that were utilized to study as well as target exosome-mediated immunosuppression, highlighting the Xenomimetic mouse (X-mouse) model and the Omental Tumor Xenograft (OTX) model that were featured in a recent study to evaluate the efficacy of a novel phosphatidylserine-binding molecule for targeting immunosuppressive tumor-associated exosomes.

PD-L1 Expression on Circulating Tumour-Derived Microvesicles as a Complementary Tool for Stratification of High-Grade Serous Ovarian Cancer Patients

BACKGROUND

Ovarian cancer (OC) has recently attracted attention for the use of PD-1/PD-L1 axis blocking agents, with durable activity reported only in a subset of patients. The most used biomarker for sensitivity to the PD-1/PD-L1 axis blockade is tumour PD-L1 status by immunohistochemistry. However, patient stratification using this method suffers from intrinsic heterogeneity of OC, likely contributing to the unsatisfactory results obtained so far. Cells communicate with each other by releasing microvesicles (MVs) that carry parental cell surface features. Thus, we hypothesised that PD-L1⁺ tumour cells (TC) and infiltrating PD-L1⁺ leukocytes should shed MVs carrying surface PD-L1 that may serve as a proxy for the whole tumour PD-L1 status.

RESULTS

We showed for the first time the presence of measurable amounts of TC- and leukocyte-derived PD-L1⁺ MVs (range: 1.4-178.8 MVs/μL and 6.2-504.8 MVs/μL, respectively) in the plasma of high-grade serous OC (HGSOC) patients (n = 63), using a sensitive flow cytometry platform. The concentration of PD-L1⁺ MVs of either origin did not associate with the PD-L1 status of TCs and leukocytes in the tumour biopsies, suggesting that the circulating PD-L1⁺ MVs also included ones from locations not selected for immunohistochemistry analysis and represented the PD-L1 status of the whole tumour mass. In this study, we also describe the serendipitous discovery of circulating PD-L1⁺ MVs of platelet origin (10.3-2409.6 MVs/μL).

CONCLUSIONS

The enumeration of circulating PD-L1⁺ MVs in HGSOC patients may provide a novel direction for assessing the tumour PD-L1 status and contribute to HGSOC patient stratification for immunotherapy interventions. The presence of circulating PD-L1⁺ MVs of platelet origin, a finding not yet reported in HGSOC patients, warrants further studies.

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.

The Role and Clinical Interest of Extracellular Vesicles in Pregnancy and Ovarian Cancer

Ovarian cancer and pregnancy are two states in which the host immune system is exposed to novel antigens. Indeed, both the tumor and placenta must invade tissues, remodel vasculature to establish a robust blood supply, and evade detection by the immune system. Interestingly, tumor and placenta tissue use similar mechanisms to induce these necessary changes. One mediator is emerging as a key player in invasion, vascular remodeling, and immune evasion: extracellular vesicles (EVs). Many studies have identified EVs as a key mediator of cell-to-cell communication. Specifically, the cargo carried by EVs, which includes proteins, nucleic acids, and lipids, can interact with cells to induce changes in the target cell ranging from gene expression to migration and metabolism. EVs can promote cell division and tissue invasion, immunosuppression, and angiogenesis which are essential for both cancer and pregnancy. In this review, we examine the role of EVs in ovarian cancer metastasis, chemoresistance, and immune modulation. We then focus on the role of EVs in pregnancy with special attention on the vascular remodeling and regulation of the maternal immune system. Lastly, we discuss the clinical utility of EVs as markers and therapeutics for ovarian cancer and pre-eclampsia.

CML derived exosomes promote tumor favorable functional performance in T cells

Background

Leukemic cells facilitate the creation of the tumor-favorable microenvironment in the bone marrow niche using their secreted factors. There are not comprehensive details about immunosuppressive properties of chronic myelogenous leukemia-derived exosomes in the bone marrow stromal and immune compartment. We explained here that K562-derived exosomes could affect the gene expression, cytokine secretion, nitric oxide (NO) production, and redox potential of human primary cord blood-derived T cells (CB T cells).

Methods

Human primary cord blood-derived T cells were treated with K562-derived exosomes. We evaluated the expression variation of some critical genes activated in suppressor T cells. The alterations of some inflammatory and anti-inflammatory cytokines levels were assessed using ELISA assay and real-time PCR. Finally, NO production and intracellular ROS level in CB T cells were evaluated using Greiss assay and flow cytometry, respectively.

Results

Our results showed the over-expression of the genes involved in inhibitory T cells, including NQO1, PD1, and FoxP3. In contrast, genes involved in T cell activation such as CD3d and NFATc3 have been reduced significantly. Also, the expression of interleukin 10 (IL-10) and interleukin 6 (IL-6) mRNAs were significantly up-regulated in these cells upon exosome treatment. In addition, secretion of the interleukin 10, interleukin 6, and interleukin 17 (IL-17) proteins increased in T cells exposed to K562-derived exosomes. Finally, K562-derived exosomes induce significant changes in the NO production and intracellular ROS levels in CB T cells.

Conclusions

These results demonstrate that K562-derived exosomes stimulate the immunosuppressive properties in CB-derived T cells by inducing anti-inflammatory cytokines such as IL-10, reducting ROS levels, and arising of NO synthesis in these cells. Moreover, considering the elevation of FOXP3, IL-6, and IL-17 levels in these cells, exosomes secreted by CML cells may induce the fates of T cells toward tumor favorable T cells instead of conventional activated T cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08734-3.

Ovarian-Cancer-Associated Extracellular Vesicles: Microenvironmental Regulation and Potential Clinical Applications

Ovarian cancer (OC) is one of the most diagnosed gynecological cancers in women. Due to the lack of effective early stage screening, women are more often diagnosed at an advanced stage; therefore, it is associated with poor patient outcomes. There are a lack of tools to identify patients at the highest risk of developing this cancer. Moreover, early detection strategies, therapeutic approaches, and real-time monitoring of responses to treatment to improve survival and quality of life are also inadequate. Tumor development and progression are dependent upon cell-to-cell communication, allowing cancer cells to re-program cells not only within the surrounding tumor microenvironment, but also at distant sites. Recent studies established that extracellular vesicles (EVs) mediate bi-directional communication between normal and cancerous cells. EVs are highly stable membrane vesicles that are released from a wide range of cells, including healthy and cancer cells. They contain tissue-specific signaling molecules (e.g., proteins and miRNA) and, once released, regulate target cell phenotypes, inducing a pro-tumorigenic and immunosuppressive phenotype to contribute to tumor growth and metastasis as well as proximal and distal cell function. Thus, EVs are a “fingerprint” of their cell of origin and reflect the metabolic status. Additionally, via the capacity to evade the immune system and remain stable over long periods in circulation, EVs can be potent therapeutic agents. This review examines the potential role of EVs in the different aspects of the tumor microenvironment in OC, as well as their application in diagnosis, delivery of therapeutic agents, and disease monitoring.

Extracellular Vesicle Transmission of Chemoresistance to Ovarian Cancer Cells Is Associated with Hypoxia-Induced Expression of Glycolytic Pathway Proteins, and Prediction of Epithelial Ovarian Cancer Disease Recurrence

Simple Summary

Ovarian cancer is one of the most lethal cancers affecting women worldwide. Its high mortality rate is often attributed to the non-specific nature of early symptoms of the disease. Developing a better understanding of the disease progression and identifying clinically useful biomarkers that aid in clinical management are requisite to reducing the mortality rate of ovarian cancer. Reduced oxygen tension (i.e., hypoxia) is not only a characteristic of solid tumors but may also enhance the metastatic capacity of tumors by inducing the release of tumor growth promoting factors. Recently, it has been proposed that small tumor-derived extracellular vesicles (sEVs) facilitate cancer progression. In this study, we established that sEVs produced under low oxygen tension induce a metabolic switch in ovarian cancer cells associated with changes in glycolytic pathway proteins that promote resistance to carboplatin. Significantly, we identified a suite of sEV-associated glycolysis pathway proteins that are present in patients with ovarian cancer that can predict disease recurrence with over 90% accuracy.

Abstract

Hypoxia is a key regulator of cancer progression and chemoresistance. Ambiguity remains about how cancer cells adapt to hypoxic microenvironments and transfer oncogenic factors to surrounding cells. In this study, we determined the effects of hypoxia on the bioactivity of sEVs in a panel of ovarian cancer (OvCar) cell lines. The data obtained demonstrate a varying degree of platinum resistance induced in OvCar cells when exposed to low oxygen tension (1% oxygen). Using quantitative mass spectrometry (Sequential Window Acquisition of All Theoretical Fragment Ion Mass Spectra, SWATH) and targeted multiple reaction monitoring (MRM), we identified a suite of proteins associated with glycolysis that change under hypoxic conditions in cells and sEVs. Interestingly, we identified a differential response to hypoxia in the OvCar cell lines and their secreted sEVs, highlighting the cells’ heterogeneity. Proteins are involved in metabolic reprogramming such as glycolysis, including putative hexokinase (HK), UDP-glucuronosyltransferase 1–6 (UD16), and 6-phosphogluconolactonase (6 PGL), and their presence correlates with the induction of platinum resistance. Furthermore, when normoxic cells were exposed to sEVs from hypoxic cells, platinum-resistance increased significantly (p < 0.05). Altered chemoresistance was associated with changes in glycolysis and fatty acid synthesis. Finally, sEVs isolated from a clinical cohort (n = 31) were also found to be enriched in glycolysis-pathway proteins, especially in patients with recurrent disease. These data support the hypothesis that hypoxia induces changes in sEVs composition and bioactivity that confers carboplatin resistance on target cells. Furthermore, we propose that the expression of sEV-associated glycolysis-pathway proteins is predictive of ovarian cancer recurrence and is of clinical utility in disease management.

Engineered EV-Mimetic Nanoparticles as Therapeutic Delivery Vehicles for High-Grade Serous Ovarian Cancer

Simple Summary

In this review, we begin with the role of natural extracellular vesicles (EVs) in high-grade serous ovarian cancer (HGSOC). Then, we narrow our focus on the advantages of using EV-mimetic nanoparticles as a delivery vehicle for RNAi therapy and other chemotherapeutics. Furthermore, we discuss the challenges of the clinical translation of engineering EV mimetic drug delivery systems and the promising directions of further development.

Abstract

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy among women. Several obstacles impede the early diagnosis and effective treatment options for ovarian cancer (OC) patients, which most importantly include the development of platinum-drug-resistant strains. Currently, extensive efforts are being put into the development of strategies capable of effectively circumventing the physical and biological barriers present in the peritoneal cavity of metastatic OC patients, representing a late stage of gastrointestinal and gynecological cancer with an extremely poor prognosis. Naturally occurring extracellular vesicles (EVs) have been shown to play a pivotal role in progression of OC and are now being harnessed as a delivery vehicle for cancer chemotherapeutics. However, there are limitations to their clinical application due to current challenges in their preparation techniques. Intriguingly, there is a recent drive towards the use of engineered synthetic EVs for the delivery of chemotherapeutics and RNA interference therapy (RNAi), as they show the promise of overcoming the obstacles in the treatment of OC patients. This review discusses the therapeutic application of EVs in OC and elucidates the potential use of engineered EV-mimetic nanoparticles as a delivery vehicle for RNAi therapy and other chemotherapeutics, which would potentially improve clinical outcomes of OC patients.

Exosomal CD47 Plays an Essential Role in Immune Evasion in Ovarian Cancer

Ovarian cancer is largely diagnosed at advanced stages upon detection of multiple peritoneal dissemination, resulting in poor outcomes. CD47 is overexpressed in tumors, facilitates tumor immune evasion, and is located on exosomes. We aimed to investigate the role of exosomal CD47 in ovarian cancer progression. Prognostic significance of CD47 expression in ovarian cancer was examined using a public database including 1,435 patients and validated with 26 patients at our institution. CD47 expression was associated with poor progression-free survival and inversely correlated with macrophage infiltration in ovarian cancer tissues. Exosomes were collected from ovarian cancer cell lines, and CD47 expression on exosomes was confirmed via flow cytometry. Inhibition of exosome secretion with GW4869 and exosome uptake with 5-(N-ethyl-N-isopropyl)-amiloride inhibited the surface CD47 expression on ovarian cancer cells and promoted phagocytosis by macrophages. RAB27A (a key regulator of exosome release) knockdown inhibited exosome secretion and led to CD47 downregulation in ovarian cancer cells. In a xenograft mouse model, suppression of the release of tumor-derived exosomes by GW4869 or RAB27A knockdown suppressed tumor progression and enhanced M1 macrophage phagocytosis in cancer tissues. Collectively, CD47 expression was correlated with poor prognoses in patients with ovarian cancer, suggesting the importance of immune evasion. CD47 was expressed on exosomes and the inhibition of exosome secretion and/or uptake enhanced cancer cell phagocytosis by macrophages, and thus, suppressed peritoneal dissemination. This suggests the potential of a novel immune checkpoint therapeutic agent that focuses on exosomes. IMPLICATIONS: Mechanistic insight from the current study suggests that exosomal CD47 may be an advantageous therapeutic target in ovarian cancer.

Role of exosomes in the immune microenvironment of ovarian cancer

Exosomes are excretory vesicles that can deliver a variety of bioactive cargo molecules to the extracellular environment. Accumulating evidence demonstrates exosome participation in intercellular communication, immune response, inflammatory response and they even play an essential role in affecting the tumor immune microenvironment. The role of exosomes in the immune microenvironment of ovarian cancer is mainly divided into suppression and stimulation. On one hand exosomes can stimulate the innate and adaptive immune systems by activating dendritic cells (DCs), natural killer cells and T cells, allowing these immune cells exert an antitumorigenic effect. On the other hand, ovarian cancer-derived exosomes initiate cross-talk with immunosuppressive effector cells, which subsequently cause immune evasion; one of the hallmarks of cancer. Exosomes induce the polarization of macrophages in M2 phenotype and induce apoptosis of lymphocytes and DCs. Exosomes further activate additional immunosuppressive effector cells (myeloid-derived suppressor cells and regulatory T cells) that induce fibroblasts to differentiate into cancer-associated fibroblasts. Exosomes also induce the tumorigenicity of mesenchymal stem cells to exert additional immune suppression. Furthermore, besides mediating the intercellular communication, exosomes carry microRNAs (miRNAs), proteins and lipids to the tumor microenvironment, which collectively promotes ovarian cancer cells to proliferate, invade and tumors to metastasize. Studying proteins, lipids and miRNAs carried by exosomes could potentially be used as an early diagnostic marker of ovarian cancer for designing treatment strategies.

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.

Preclinical evaluation of cancer immune therapy using patient-derived tumor antigen-specific T cells in a novel xenograft platform

OBJECTIVES

With a rapidly growing list of candidate immune-based cancer therapeutics, there is a critical need to generate highly reliable animal models to preclinically evaluate the efficacy of emerging immune-based therapies, facilitating successful clinical translation. Our aim was to design and validate a novel in vivo model (called Xenomimetic or 'X' mouse) that allows monitoring of the ability of human tumor-specific T cells to suppress tumor growth following their entry into the tumor.

METHODS

Tumor xenografts are established rapidly in the greater omentum of globally immunodeficient NOD-scid IL2Rγ^null (NSG) mice following an intraperitoneal injection of melanoma target cells expressing tumor neoantigen peptides, as well as green fluorescent protein and/or luciferase. Changes in tumor burden, as well as in the number and phenotype of adoptively transferred patient-derived tumor neoantigen-specific T cells in response to immunotherapy, are measured by imaging to detect fluorescence/luminescence and flow cytometry, respectively.

RESULTS

The tumors progress rapidly and disseminate in the mice unless patient-derived tumor-specific T cells are introduced. An initial T cell-mediated tumor arrest is later followed by a tumor escape, which correlates with the upregulation of the checkpoint molecules programmed cell death-1 (PD-1) and lymphocyte-activation gene 3 (LAG3) on T cells. Treatment with immune-based therapies that target these checkpoints, such as anti-PD-1 antibody (nivolumab) or interleukin-12 (IL-12), prevented or delayed the tumor escape. Furthermore, IL-12 treatment suppressed PD-1 and LAG3 upregulation on T cells.

CONCLUSION

Together, these results validate the X-mouse model and establish its potential to preclinically evaluate the therapeutic efficacy of immune-based therapies.

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.

SJI 2020 special issue: A catalogue of Ovarian Cancer targets for CAR therapy

Ovarian Cancer (OC) is currently difficult to cure, mainly due to its late detection and the advanced state of the disease at the time of diagnosis. Therefore, conventional treatments such as debulking surgery and combination chemotherapy are rarely able to control progression of the tumour, and relapses are frequent. Alternative therapies are currently being evaluated, including immunotherapy and advanced T cell-based therapy. In the present review, we will focus on a description of those Chimeric Antigen Receptors (CARs) that have been validated in the laboratory or are being tested in the clinic. Numerous target antigens have been defined due to the identification of OC biomarkers, and many are being used as CAR targets. We provide an exhaustive list of these constructs and their current status. Despite being innovative and efficient, the OC-specific CARs face a barrier to their clinical efficacy: the tumour microenvironment (TME). Indeed, effector cells expressing CARs have been shown to be severely inhibited, rendering the CAR T cells useless once at the tumour site. Herein, we give a thorough description of the highly immunosuppressive OC TME and present recent studies and innovations that have enabled CAR T cells to counteract this negative environment and to destroy tumours.

Exosomes as mediators of immune regulation and immunotherapy in cancer

Exosomes are nanosized extracellular vesicles of endosomal origin that enclose a multitude of functional biomolecules. Exosomes have emerged as key players of intercellular communication in physiological and pathological conditions. In cancer, depending on the context, exosomes can oppose or potentiate the development of an aggressive tumor microenvironment, thereby impacting tumor progression and clinical outcome. Increasing evidence has established exosomes as important mediators of immune regulation in cancer, as they deliver a plethora of signals that can either support or restrain immunosuppression of lymphoid and myeloid cell populations in tumors. Here, we review the current knowledge related to exosome-mediated regulation of lymphoid (T lymphocytes, B lymphocytes, and NK cells) and myeloid (macrophages, dendritic cells, monocytes, myeloid-derived suppressor cells, and neutrophils) cell populations in cancer. We also discuss the translational potential of engineered exosomes as immunomodulatory agents for cancer therapy.

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.

An Immunosuppressive Effect of Melanoma-derived Exosomes on NY-ESO-1 Antigen-specific Human CD8+ T Cells is Dependent on IL-10 and Independent of BRAFV600E Mutation in Melanoma Cell Lines

Exosomes, including human melanoma-derived exosomes (HMEX), are known to suppress the function of immune effector cells, which for HMEX has been associated with the surface presence of the immune checkpoint ligand PD-L1. This study investigated the relationship between the BRAF mutational status of melanoma cells and the inhibition of secreted HMEX exosomes on antigen-specific human T cells. Exosomes were isolated from two melanoma cell lines, 2183-Her4 and 888-mel, which are genetically wild-type BRAF^WT and BRAF^V600E, respectively. HMEX were isolated using a modified, size-exclusion chromatography (SEC) method shown to reduce co-isolation of non-exosome-associated cytokines compared to ultracentrifugation isolation. The immunoinhibitory effect of the exosomes was tested in vitro on patient-derived NY-ESO-1-specific CD8⁺ T cells challenged with NY-ESO-1 antigen. HMEX from both cell lines inhibited the immune response of antigen-specific T cells comparably, as evidenced by the reduction of IFN-γ and TNF-α in NY-ESO-1 tetramer-positive cells. This inhibition could be partially reversed by the presence of anti-PD-L1 and anti-IL-10 antibodies. IL-10 has been demonstrated to be a critical pathway for sustaining enhanced tumorigenesis in BRAF^V600E mutant cells compared to BRAF^WT melanoma cells. Thus, we demonstrate that HMEX inhibit antigen-specific T cell responses independent of the BRAF mutational status of the parent cells. In addition, PD-L1 and IL-10 contribute to the HMEX-mediated immunosuppression of antigen-specific human T cells. The inhibitory capacity of exosomes should be taken into consideration when developing therapies that are reliant upon the potency of customized, antigen-specific effector T cells.

Recent Advances in Bio-Sensing Methods for the Detection of Tumor Exosomes

Exosomes, small vesicles with the diameters of 40-160 nm, play an important role in intercellular transport and communication. Exosomes are rich in many kinds of biomolecules, and differential expression of exosomal contents directly reflects the state of the original cells. Therefore, the tumor exosomes are appearing as promising biomarkers in liquid biopsy, and highly sensitive and specific detection of tumor exosomes may provide the information for the early diagnosis, real-time monitoring and treatment of the tumors. In this review, we summarized the recent advances in the detection of tumor exosomes, mainly focusing on the use of different analytical techniques, such as optical and electrochemical methods as well as that combination with newly-emerging microfluidic techniques, thereby providing valuable information for the application in the clinical diagnosis and management of the tumors.

A Clinician's Guide to Cancer-Derived Exosomes: Immune Interactions and Therapeutic Implications

Understanding of the role of immunity in the regulation of cancer growth continues to rapidly increase. This is fuelled by the impressive results yielded in recent years by immune checkpoint inhibitors, which block regulatory pathways to increase immune-mediated cancer destruction. Exosomes are cell-secreted membranous nanoscale vesicles that play important roles in regulating physiological and pathophysiological processes. Cancer-derived exosomes (CDEXs) and their biologically-active cargos have been proven to have varied effects in malignant progression, including the promotion of angiogenesis, metastasis, and favorable microenvironment modification. More recently, there is an increasing appreciation of their role in immune evasion. In addition to CDEXs, there are immune-derived exosomes that facilitate communication between immune cells in the non-malignant setting. Investigation of cancer-mediated mechanisms behind interruption or modification of these normal exosomal pathways may provide further understanding of how malignant immune evasion is accomplished. Accumulating evidence indicates that immune-active CDEXs also have the potential to impact clinical oncological management. Whilst immune checkpoint inhibitors have well-established pharmacologically-targeted pathways involving the immune system, other widely used treatments such as radiation and cytotoxic chemotherapies do not. Thus, investigating exosomes in immunotherapy is important for the development of next-generation combination therapies. In this article, we review the ways in which CDEXs impact individual immune cell types and how this contributes to the development of immune evasion. We discuss the relevance of lymphocytes and myeloid-lineage cells in the control of malignancy. In addition, we highlight the ways that CDEXs and their immune effects can impact current cancer therapies and the resulting clinical implications.

Targeting Cancer Stem Cells to Overcome Therapy Resistance in Ovarian Cancer

Ovarian cancer is the most lethal gynecological malignancy due to its late detection and high recurrence rate. Resistance to conventional platinum-based therapies and metastasis are attributed to a population of cells within tumors called cancer stem cells, which possess stem-like features and are able to recapitulate new tumors. Recent studies have deepened the understanding of the biology of ovarian cancer stem cells and their special properties and have identified multiple markers and signaling pathways responsible for their self-renewal abilities. Targeting cancer stem cells represents the most promising strategy for overcoming therapy resistance and reducing mortality in ovarian cancer, but further efforts must be made to improve our understanding of the mechanisms involved in therapy resistance. In this review, we summarize our current knowledge about ovarian cancer stem cells, their involvement in metastasis and their interactions with the tumor microenvironment; we also discuss the therapeutic approaches that are being developed to target them to prevent tumor relapse.

Molecular profiles and immunomodulatory activities of glioblastoma-derived exosomes

Background

Glioblastoma is one of the most immunosuppressive human tumors. Emerging data suggest that glioblastoma-derived exosomes (GBex) reprogram the tumor microenvironment into a tumor-promoting milieu by mechanisms that not yet understood.

Methods

Exosomes were isolated from supernatants of glioblastoma cell lines by size exclusion chromatography. The GBex endosomal origin, size, protein cargos, and ex vivo effects on immune cell functions were determined. GBex were injected intravenously into mice to evaluate their ability to in vivo modulate normal immune cell subsets.

Results

GBex carried immunosuppressive proteins, including FasL, TRAIL, CTLA-4, CD39, and CD73, but contained few immunostimulatory proteins. GBex co-incubated with primary human immune cells induced simultaneous activation of multiple molecular pathways. In CD8⁺ T cells, GBex suppressed TNF-α and INF-γ release and mediated apoptosis. GBex suppressed natural killer (NK) and CD4⁺ T-cell activation. GBex activated the NF-κB pathway in macrophages and promoted their differentiation into M2 cells. Inhibition of the NF-κB pathway in macrophages reversed the GBex-mediated effects. GBex-driven reprogramming of macrophages involved the release of soluble factors that promoted tumor proliferation in vitro. In mice injected with GBex, the frequency of splenic CD8⁺ T cells, NK cells, and M1-like macrophages was reduced, while that of naïve and M2-like macrophages increased (P < .05).

Conclusions

GBex reprogrammed functions of all types of immune cells in vitro and altered their frequency in vivo. By creating and sustaining a highly immunosuppressive environment, GBex play a key role in promoting tumor progression.

Tumor-Derived Extracellular Vesicles Impair CD171-Specific CD4+ CAR T Cell Efficacy

Chimeric antigen receptor (CAR) T cell efficacy against solid tumors is currently limited by several immune escape mechanisms, which may include tumor-derived extracellular vesicles. Advanced neuroblastoma is an aggressive childhood tumor without curative treatment options for most relapsed patients today. We here evaluated the role of tumor-derived extracellular vesicles on the efficacy of CAR T cells targeting the neuroblastoma-specific antigen, CD171. For this purpose, CAR T cell activation, cytokine production, exhaustion, and tumor cell-directed cytotoxicity upon co-culture was evaluated. Tumor-derived extracellular vesicles isolated from SH-SY5Y neuroblastoma cells neither affected CAR T cell activation nor expression of inhibitory markers. Importantly, exposure of CD4⁺ CD171-specific CAR T cells to tumor-derived extracellular vesicles significantly impaired tumor cytotoxicity of CAR T cells. This effect was independent of neurotrophic receptor tyrosine kinases 1 or 2 (NTRK1, NTRK2) expression, which is known to impact immune responses against neuroblastoma. Our results demonstrate for the first time the impact of tumor-derived extracellular vesicles and non-cell-mediated tumor-suppressive effects on CD4⁺ CAR T cell efficacy in a preclinical setting. We conclude that these factors should be considered for any CAR T cell-based therapy to make CAR T cell therapy successful against solid tumors.

Pathophysiological Role and Potential Therapeutic Exploitation of Exosomes in Ovarian Cancer

Exosomes are extracellular vesicles involved in several biological and pathological molecules and can carry many bioactive materials to target cells. They work as important mediators of cell-cell communication and play essential roles in many diseases, especially in cancer. Ovarian cancer is one of the most common gynecological malignancies. Most patients are diagnosed at advanced stages involving widespread peritoneal dissemination, resulting in poor prognosis. Emerging evidence has shown that exosomes play vital roles throughout the progression of ovarian cancer. Moreover, the development of engineered exosome-based therapeutic applications— including drug delivery systems, biomolecular targets and immune therapy—has increased drastically. Herein, we review the functional features of exosomes in ovarian cancer progression and the therapeutic application potential of exosomes as novel cancer treatments.

Bioengineering Bacterial Vesicle-Coated Polymeric Nanomedicine for Enhanced Cancer Immunotherapy and Metastasis Prevention

We herein propose a bioengineering approach where bacterial outer membrane vesicles (OMVs) were coated on drug-loaded polymeric micelles to generate an innovative nanomedicine for effective cancer immunotherapy and metastasis prevention. Whereas OMVs could activate the host immune response for cancer immunotherapy, the loaded drug within polymeric micelles would exert both chemotherapeutic and immunomodulatory roles to sensitize cancer cells to cytotoxic T lymphocytes (CTLs) and to kill cancer cells directly. We demonstrated that the systemic injection of such a bioinspired immunotherapeutic agent would not only provide effective protective immunity against melanoma occurrence but also significantly inhibited tumor growth in vivo and extended the survival rate of melanoma mice. Importantly, the nanomedicine could also effectively inhibit tumor metastasis to the lung. The bioinspired immunomodulatory nanomedicine we have developed repurposes the bacterial-based formulation for cancer immunotherapy, which also defines a useful bioengineering strategy to the improve current cancer immunotherapeutic agents and delivery systems.

Phenotypic analysis of extracellular vesicles: a review on the applications of fluorescence

Extracellular vesicles (EVs) have numerous potential applications in the field of healthcare and diagnostics, and research into their biological functions is rapidly increasing. Mainly because of their small size and heterogeneity, there are significant challenges associated with their analysis and despite overt evidence of the potential of EVs in clinical diagnostic practice, guidelines for analytical procedures have not yet been properly established. Here, we present an overview of the main methods for studying the properties of EVs based on the principles of fluorescence. Setting aside the isolation, purification and physicochemical characterization strategies which answer questions about the size, surface charge and stability of EVs (reviewed elsewhere), we focus on available optical tools that enable the direct analysis of phenotype and mechanisms of interaction with tissues. In brief, the topics on which we elaborate range from the most popular approaches such as nanoparticle tracking analysis and flow cytometry, to less commonly used techniques such as fluorescence depolarization and microarrays as well as emerging areas such as fast fluorescence lifetime imaging microscopy (FLIM). We highlight that understanding the strengths and limitations of each method is essential for choosing the most appropriate combination of analytical tools. Finally, future directions of this rapidly developing area of medical diagnostics are discussed.

Exosomes released by breast cancer cells under mild hyperthermic stress possess immunogenic potential and modulate polarization in vitro in macrophages

Macrophages play a dual role in tumor initiation and progression, with both tumor-promoting and tumor-suppressive effects; hence, it is essential to understand the distinct responses of macrophages to tumor progression and therapy. Mild hyperthermia has gained importance as a therapeutic regimen against cancer due to its immunogenic nature, efficacy, and potential synergy with other therapies, yet the response of macrophages to molecular signals from hyperthermic cancer cells has not yet been clearly defined. Due to limited response rate of breast cancer to conventional therapeutics the development, and understanding of alternative therapies like hyperthermia is pertinent. In order to determine conditions corresponding to mild thermal dose, cytotoxicity of different hyperthermic temperatures and treatment durations were tested in normal murine macrophages and breast cancer cell lines. Examination of exosome release in hyperthermia-treated cancer cells revealed enhanced efflux and a larger size of exosomes released under hyperthermic stress. Exposure of naïve murine macrophages to exosomes released from 4T1 and EMT-6 cells posthyperthermia treatment, led to an increased expression of specific macrophage activation markers. Further, exosomes released by hyperthermia-treated cancer cells had increased content of heat shock protein 70 (Hsp70). Together, these results suggest a potential immunogenic role for exosomes released from cancer cells treated with mild hyperthermia.

Exosome and Secretion: Action On?

Originally treated as part of a cellular waste, extracellular vesicles (EVs) are being shown to possess a vast variety of functions, of which exosome is the most studied one. Most cells, such as tumor cells, immunocytes, and fibroblasts can secrete exosomes, especially under certain stresses the amount is much higher, and the contents of exosome represent the status of the donor cells and the tumor microenvironment. As crucial transporters for cells' content exchange, much attention has been raised in the utilities of exosomes to suppress immune response, and to modify a microenvironment favorable for cancer progression. Exosomal immune checkpoints, such as programmed cell death ligand 1 (PD-L1), contribute to immunosuppression and are associated with anti-PD-1 response. Many forms of soluble immune checkpoint receptors have also been shown to influence efficacy mediated by their therapeutic antibodies. Therefore, targeting pro-tumorous exosomes may achieve antitumor effect supplementary to existing therapies. Exosome, itself natural liposome-like structure, allows it to be a potential drug delivery tool.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Role of the Exosome in Ovarian Cancer Progression and Its Potential as a Therapeutic Target

Peritoneal dissemination is a distinct form of metastasis in ovarian cancer that precedes hematogenic or lymphatic metastasis. Exosomes are extracellular vesicles of 30–150 nm in diameter secreted by different cell types and internalized by target cells. There is emerging evidence that exosomes facilitate the peritoneal dissemination of ovarian cancer by mediating intercellular communication between cancer cells and the tumor microenvironment through the transfer of nucleic acids, proteins, and lipids. Furthermore, therapeutic applications of exosomes as drug cargo delivery are attracting research interest because exosomes are stabilized in circulation. This review highlights the functions of exosomes in each process of the peritoneal dissemination of ovarian cancer and discusses their potential for cancer therapeutics.

Functions of Exosomes in the Triangular Relationship between the Tumor, Inflammation, and Immunity in the Tumor Microenvironment

Exosomes are extracellular vesicles that contain diverse components such as genetic materials, proteins, and lipids. Owing to their distinct derivation and tissue specificity, exosomes act as double-edged swords during the development of neoplasms. On the one hand, tumor-derived exosomes can modulate the immune system during tumorigenesis by regulating inflammatory cell infiltration and oxidative stress and by promoting epithelial-to-mesenchymal transition and immune-induced tumor dormancy. On the other hand, components of specific immune cell-derived exosomes may contribute to the efficacy of antitumor immunotherapy. In this review, we demonstrate the pivotal role of exosomes in the triangular relationship in the tumor microenvironment between the tumor, inflammation, and immunity, which may provide potential strategies for tumor immunotherapy at genetic and cellular levels.

Targeting autophagy potentiates the anti-tumor effect of PARP inhibitor in pediatric chronic myeloid leukemia

Due to its potent cytotoxicity in BRCA-mutated tumors, synthetic lethality elicited by poly (ADP-ribose) polymerase (PARP) inhibitor gives renewed enthusiasm to researching and developing anti-cancer therapies. Chronic myeloid leukemia (CML) is a type of cancers that starts in certain blood-forming cells of the bone marrow. Here, we showed that poly (ADP-ribose) polymerase (PARP) inhibitor talazoparib could induce a concentration-dependent cytotoxicity in CML cells derived from pediatric patients. During talazoparib treatment, autophagy was markedly activated, which was confirmed by the accumulation of autophagosomes, decrease of SQSTM1 and up-regulation of LC3-II. Inhibition of autophagy by pharmaceutical inhibitor chloroquine or small-interfering RNA siATG5 significantly increased the cytotoxicity of talazoparib in pediatric CML cells and elicited synergistic anti-tumor effect in patient-derived xenograft model. Our data demonstrated that autophagy played a cyto-protective role in talazoparib-treated pediatric CML and co-treatment with talazoparib and autophagy inhibitor could induce synergetic anti-tumor effect, providing novel insights for pediatric CML treatment.

Small extracellular vesicles containing arginase-1 suppress T-cell responses and promote tumor growth in ovarian carcinoma

Tumor-driven immune suppression is a major barrier to successful immunotherapy in ovarian carcinomas (OvCa). Among various mechanisms responsible for immune suppression, arginase-1 (ARG1)-carrying small extracellular vesicles (EVs) emerge as important contributors to tumor growth and tumor escape from the host immune system. Here, we report that small EVs found in the ascites and plasma of OvCa patients contain ARG1. EVs suppress proliferation of CD4⁺ and CD8⁺ T-cells in vitro and in vivo in OvCa mouse models. In mice, ARG1-containing EVs are transported to draining lymph nodes, taken up by dendritic cells and inhibit antigen-specific T-cell proliferation. Increased expression of ARG1 in mouse OvCa cells is associated with accelerated tumor progression that can be blocked by an arginase inhibitor. Altogether, our studies show that tumor cells use EVs as vehicles to carry over long distances and deliver to immune cells a metabolic checkpoint molecule – ARG1, mitigating anti-tumor immune responses.

Cancer cells employ a variety of ways to escape the immune system. Here, the authors show that ovarian cancer cells produce small extracellular vescicles containing arginase 1 that are taken up by dendritic cells in the draining lymph nodes, resulting in inhibition of antigen-specific T-cell proliferation.

SALL4-mediated upregulation of exosomal miR-146a-5p drives T-cell exhaustion by M2 tumor-associated macrophages in HCC

Emerging evidence indicates that cancer cell-derived exosomes contribute to cancer progression through the modulation of tumor microenvironment, but the underlying mechanisms are not fully elucidated. Here, we reported that hepatocellular carcinoma (HCC)-derived exosomes could remodel macrophages by activating NF-κB signaling and inducing pro-inflammatory factors, and resulted in M2-polarized tumor-associated macrophages. In addition, the expression of IFN-γ and TNF-α was inhibited, while the expression of inhibitory receptors such as PD-1 and CTLA-4 was upregulated in T cells by HCC-derived exosome educated macrophages. Data also revealed that HCC exosomes were enriched with miR-146a-5p and promoted M2-polarization. Further investigation demonstrated that the transcription factor Sal-like protein-4 (SALL4) was critical for regulating miR-146a-5p in HCC exosomes and M2-polarization. Mechanistically, SALL4 could bind to the promoter of miR-146a-5p, and directly controlled its expression in exosomes. Blocking the SALL4/miR-146a-5p interaction in HCC reduced the expression of inhibitory receptors on T cells, reversed T cell exhaustion, and delayed HCC progression in DEN/CCL₄-induced HCC mice. In conclusion, identification of a role of the exosomal SALL4/miR-146a-5p regulatory axis in M2-polarization as well as HCC progression provides potential targets for therapeutic and diagnostic applications in liver cancer.