Role of exosomes in tumour and transplant immune regulation

Killing two birds with one stone: Abscopal effect mechanism and its application prospect in radiotherapy

Abscopal effects are characterized by the emergence of neoplasms in regions unrelated to the primary radiation therapy site, displaying a gradual attenuation or regression throughout the progression of radiation therapy, which have been of interest to scientists since Mole's proposal in 1953. The incidence of abscopal effects in radiation therapy is intricately linked to the immune system, with both innate and adaptive immune responses playing crucial roles. Biological factors impacting abscopal effects ultimately exert their influence on the intricate workings of the immune system. Although abscopal effects are rarely observed in clinical cases, the underlying mechanism remains uncertain. This article examines the biological and physical factors influencing abscopal effects of radiotherapy. Through a review of preclinical and clinical studies, this article aims to offer a comprehensive understanding of abscopal effects and proposes new avenues for future research in this field. The findings presented in this article serve as a valuable reference for researchers seeking to explore this topic in greater depth.

Exosomes: a promising avenue for cancer diagnosis beyond treatment

Exosomes, extracellular vesicles secreted by cells, have garnered significant attention in recent years for their remarkable therapeutic potential. These nanoscale carriers can be harnessed for the targeted delivery of therapeutic agents, such as pharmaceuticals, proteins, and nucleic acids, across biological barriers. This versatile attribute of exosomes is a promising modality for precision medicine applications, notably in the realm of cancer therapy. However, despite their substantial therapeutic potential, exosomes still confront challenges tied to standardization and scalability that impede their practice in clinical applications. Moreover, heterogeneity in isolation methodologies and limited cargo loading mechanisms pose obstacles to ensuring consistent outcomes, thereby constraining their therapeutic utility. In contrast, exosomes exhibit a distinct advantage in cancer diagnosis, as they harbor specific signatures reflective of the tumor's genetic and proteomic profile. This characteristic endows them with the potential to serve as valuable liquid biopsies for non-invasive and real-time monitoring, making possible early cancer detection for the development of personalized treatment strategies. In this review, we provide an extensive evaluation of the advancements in exosome research, critically examining their advantages and limitations in the context of cancer therapy and early diagnosis. Furthermore, we present a curated overview of the most recent technological innovations utilizing exosomes, with a focus on enhancing the efficacy of early cancer detection.

Notochordal cells: A potential therapeutic option for intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a prevalent musculoskeletal degenerative disorder worldwide, and ~40% of chronic low back pain cases are associated with IDD. Although the pathogenesis of IDD remains unclear, the reduction in nucleus pulposus cells (NPCs) and degradation of the extracellular matrix (ECM) are critical factors contributing to IDD. Notochordal cells (NCs), derived from the notochord, which rapidly degrades after birth and is eventually replaced by NPCs, play a crucial role in maintaining ECM homeostasis and preventing NPCs apoptosis. Current treatments for IDD only provide symptomatic relief, while lacking the ability to inhibit or reverse its progression. However, NCs and their secretions possess anti-inflammatory properties and promote NPCs proliferation, leading to ECM formation. Therefore, in recent years, NCs therapy targeting the underlying cause of IDD has emerged as a novel treatment strategy. This article provides a comprehensive review of the latest research progress on NCs for IDD, covering their biological characteristics, specific markers, possible mechanisms involved in IDD and therapeutic effects. It also highlights significant future directions in this field to facilitate further exploration of the pathogenesis of IDD and the development of new therapies based on NCs strategies.

Natural killer cell-derived exosomes for cancer immunotherapy: innovative therapeutics art

Chimeric antigen receptor natural killer cells (CAR-NK) promote off-the-shelf cellular therapy for solid tumors and malignancy.However,, the development of CAR-NK is due to their immune surveillance uncertainty and cytotoxicity challenge was restricted. Natural killer cell-derived exosome (NK-Exo) combine crucial targeted cellular therapies of NK cell therapies with unique non-toxic Exo as a self-origin shuttle against cancer immunotherapy. This review study covers cytokines, adoptive (autologous and allogenic) NK immunotherapy, stimulatory and regulatory functions, and cell-free derivatives from NK cells. The future path of NK-Exo cytotoxicity and anti-tumor activity with considering non-caspase-independent/dependent apoptosis and Fas/FasL pathway in cancer immunotherapy. Finally, the significance and implication of NK-Exo therapeutics through combination therapy and the development of emerging approaches for the purification and delivery NK-Exo to severe immune and tumor cells and tissues were discussed in detail.

Low-dose aspirin can inhibit exosomal release induced by radiotherapy in breast cancer and attenuate its inhibitory effect on NK cell proliferation

BACKGROUND

Breast cancer (BC) seriously threatens women's health. Aspirin plays a key role in the treatment and prognosis of BC.

OBJECTIVE

To explore the effect of low-dose aspirin on BC radiotherapy through the mechanism of exosomes and natural killer (NK) cells.

METHODS

BC cells were injected into the left chest wall to establish a BC model in nude mice. Tumor morphology and size were observed. Immunohistochemical staining for Ki-67 was used to observe the proliferation of tumor cells. TUNEL was used to detect the apoptosis of cancer cells. Protein levels of exosomal biogenesis- and secretion-related genes (Rab 11, Rab27a, Rab27b, CD63, and Alix) were detected by Western blot. Flow cytometry was used to detect apoptosis. Transwell assays were used to detect cell migration. A clonogenic assay was used to detect cell proliferation. Exosomes of BT549 and 4T1-Luc cells were extracted and observed by electron microscopy. After the coculture of exosomes and NK cells, the activity of NK cells was detected by CCK-8.

RESULTS

The protein expression of genes related to exosomal genesis and secretion (Rab 11, Rab27a, Rab27b, CD63, and Alix) in BT549 and 4T1-Luc cells was upregulated under radiotherapy treatment. Low doses of aspirin inhibited exosome release from BT549 and 4T1-Luc cells and alleviated the inhibitory effect of BC cell exosomes on NK cell proliferation. In addition, knocking down Rab27a reduced the protein levels of exosome-related and secretion-related genes in BC cells, further enhancing the promotive effect of aspirin on NK cell proliferation, while overexpressing Rab27a had the opposite effect. Aspirin was combined at a radiotherapeutic dose of 10 Gy to enhance the radiotherapy sensitivity of radiotherapy-tolerant BC cells (BT549R and 4T1-LucR). Animal experiments have also verified that aspirin can promote the killing effect of radiotherapy on cancer cells and significantly inhibit tumor growth.

CONCLUSION

Low doses of aspirin can inhibit the release of BC exosomes induced by radiotherapy and weaken their inhibition of NK cell proliferation, promoting radiotherapy resistance.

Extracellular Vesicles Mediate Immune Responses to Tissue-Associated Self-Antigens: Role in Solid Organ Transplantations

Transplantation is a treatment option for patients diagnosed with end-stage organ diseases; however, long-term graft survival is affected by rejection of the transplanted organ by immune and nonimmune responses. Several studies have demonstrated that both acute and chronic rejection can occur after transplantation of kidney, heart, and lungs. A strong correlation has been reported between de novo synthesis of donor-specific antibodies (HLA-DSAs) and development of both acute and chronic rejection; however, some transplant recipients with chronic rejection do not have detectable HLA-DSAs. Studies of sera from such patients demonstrate that immune responses to tissue-associated antigens (TaAgs) may also play an important role in the development of chronic rejection, either alone or in combination with HLA-DSAs. The synergistic effect between HLA-DSAs and antibodies to TaAgs is being established, but the underlying mechanism is yet to be defined. We hypothesize that HLA-DSAs damage the transplanted donor organ resulting in stress and leading to the release of extracellular vesicles, which contribute to chronic rejection. These vesicles express both donor human leukocyte antigen (HLA) and non-HLA TaAgs, which can activate antigen-presenting cells and lead to immune responses and development of antibodies to both donor HLA and non-HLA tissue-associated Ags. Extracellular vesicles (EVs) are released by cells under many circumstances due to both physiological and pathological conditions. Primarily employing clinical specimens obtained from human lung transplant recipients undergoing acute or chronic rejection, our group has demonstrated that circulating extracellular vesicles display both mismatched donor HLA molecules and lung-associated Ags (collagen-V and K-alpha 1 tubulin). This review focuses on recent studies demonstrating an important role of antibodies to tissue-associated Ags in the rejection of transplanted organs, particularly chronic rejection. We will also discuss the important role of extracellular vesicles released from transplanted organs in cross-talk between alloimmunity and autoimmunity to tissue-associated Ags after solid organ transplantation.

The Roles of Exosomes in Immunoregulation and Autoimmune Thyroid Diseases

Exosomes are extracellular microvesicles (30-150 nm) released from cells that contain proteins, lipids, RNA and DNA. They can deliver bioactive molecules and serve as carriers facilitating cell-cell communication, such as antigen presentation, inflammatory activation, autoimmune diseases (AIDs) and tumor metastasis. Recently, much attention has been attracted to the biology and functions of exosomes in immune regulation and AIDs, including autoimmune thyroid diseases (AITDs). Some studies have shown that exosomes are involved in the occurrence and development of AITDs, but they are still in the preliminary stage of exploration. This review mainly introduces the association of exosomes with immune regulation and emphasizes the potential role of exosomes in AITDs, aiming to provide new research strategies and directions for the pathogenesis and early diagnosis of AITDs.

The Impact of Inflammation on the Immune Responses to Transplantation: Tolerance or Rejection?

Transplantation (Tx) remains the optimal therapy for end-stage disease (ESD) of various solid organs. Although alloimmune events remain the leading cause of long-term allograft loss, many patients develop innate and adaptive immune responses leading to graft tolerance. The focus of this review is to provide an overview of selected aspects of the effects of inflammation on this delicate balance following solid organ transplantation. Initially, we discuss the inflammatory mediators detectable in an ESD patient. Then, the specific inflammatory mediators found post-Tx are elucidated. We examine the reciprocal relationship between donor-derived passenger leukocytes (PLs) and those of the recipient, with additional emphasis on extracellular vesicles, specifically exosomes, and we examine their role in determining the balance between tolerance and rejection. The concept of recipient antigen-presenting cell "cross-dressing" by donor exosomes is detailed. Immunological consequences of the changes undergone by cell surface antigens, including HLA molecules in donor and host immune cells activated by proinflammatory cytokines, are examined. Inflammation-mediated donor endothelial cell (EC) activation is discussed along with the effect of donor-recipient EC chimerism. Finally, as an example of a specific inflammatory mediator, a detailed analysis is provided on the dynamic role of Interleukin-6 (IL-6) and its receptor post-Tx, especially given the potential for therapeutic interdiction of this axis with monoclonal antibodies. We aim to provide a holistic as well as a reductionist perspective of the inflammation-impacted immune events that precede and follow Tx. The objective is to differentiate tolerogenic inflammation from that enhancing rejection, for potential therapeutic modifications. (Words 247).

Small Extracellular Vesicles in Transplant Rejection

Small extracellular vesicles (sEV), which are released to body fluids (e.g., serum, urine) by all types of human cells, may stimulate or inhibit the innate and adaptive immune response through multiple mechanisms. Exosomes or sEV have on their surface many key receptors of immune response, including major histocompatibility complex (MHC) components, identical to their cellular origin. They also exhibit an ability to carry antigen and target leukocytes either via interaction with cell surface receptors or intracellular delivery of inflammatory mediators, receptors, enzymes, mRNAs, and noncoding RNAs. By the transfer of donor MHC antigens to recipient antigen presenting cells sEV may also contribute to T cell allorecognition and alloresponse. Here, we review the influence of sEV on the development of rejection or tolerance in the setting of solid organ and tissue allotransplantation. We also summarize and discuss potential applications of plasma and urinary sEV as biomarkers in the context of transplantation. We focus on the attempts to use sEV as a noninvasive approach to detecting allograft rejection. Preliminary studies show that both sEV total levels and a set of specific molecules included in their cargo may be an evidence of ongoing allograft rejection.

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

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

Hurdles in treating Hurler disease: potential routes to achieve a "real" cure

Mucopolysaccharidoses (MPSs) are multiorgan devastating diseases for which hematopoietic cell transplantation (HCT) and, to a lesser extent, enzyme replacement therapy have substantially altered the course of the disease. Furthermore, they have resulted in increased overall survival, especially for Hurler disease (MPS-1). However, despite the identification of clinical predictors and harmonized transplantation protocols, disease progression still poses a significant burden to patients, although at a slower pace. To design better therapies, we need to understand why and where current therapies fail. In this review, we discuss important aspects of the underlying disease and the disease progression. We note that the majority of progressive symptoms that occur in "hard-to-treat" tissues are actually tissues that are difficult to reach, such as avascular connective tissue or tissues isolated from the circulation by a specific barrier (eg, blood-brain barrier, blood-retina barrier). Although easily reached tissues are effectively cured by HCT, disease progression is observed in these "hard-to-reach" tissues. We used these insights to critically appraise ongoing experimental endeavors with regard to their potential to overcome the encountered hurdles and improve long-term clinical outcomes in MPS patients treated with HCT.

Exosomes: Powerful weapon for cancer nano-immunoengineering

Cancer immunotherapy (CIT) that targets the tumor immune microenvironment is regarded as a revolutionary advancement in the fight against cancer. The success and failure of CIT are due to the complexity of the immunosuppressive microenvironment. Cancer nanomedicine is a potential adjuvant therapeutic strategy for immune-based combination therapy. Exosomes are natural nanomaterials that play a pivotal role in mediating intercellular communications and package delivery in the tumor microenvironment. They affect the immune response or the effectiveness of immunotherapy. In particular, exosomal PD-L1 promotes cancer progression and resistance to immunotherapy. Exosomes possess high bioavailability, biological stability, targeting specificity, low toxicity, and immune characteristics, which indicate their potential for cancer therapy. They can be engineered to act as effective cancer therapeutic tools that activate anti-tumor immune response and start immune surveillance. In the current review, we introduce the role of exosomes in a tumor immune microenvironment, highlight the application of engineered exosomes to CIT, and discuss the challenges and prospects for clinical application.

Extracellular vesicles as mediators of alloimmunity and their therapeutic potential in liver transplantation

Extracellular vesicles (EVs) are a heterogenous group of nanosized, membrane-bound particles which are released by most cell types. They are known to play an essential role in cellular communication by way of their varied cargo which includes selectively enriched proteins, lipids, and nucleic acids. In the last two decades, wide-ranging evidence has established the involvement of EVs in the regulation of immunity, with EVs released by immune and non-immune cells shown to be capable of mediating immune stimulation or suppression and to drive inflammatory, autoimmune, and infectious disease pathology. More recently, studies have demonstrated the involvement of allograft-derived EVs in alloimmune responses following transplantation, with EVs shown to be capable of eliciting allograft rejection as well as promoting tolerance. These insights are necessitating the reassessment of standard paradigms of T cell alloimmunity. In this article, we explore the latest understanding of the impact of EVs on alloresponses following transplantation and we highlight the recent technological advances which have enabled the study of EVs in clinical transplantation. Furthermore, we discuss the rapid progress afoot in the development of EVs as novel therapeutic vehicles in clinical transplantation with particular focus on liver transplantation.

AF cell derived exosomes regulate endothelial cell migration and inflammation: Implications for vascularization in intervertebral disc degeneration

AIMS

The intervertebral disc is the largest avascular organ of the body. Vascularization of the disc has been typically regarded as a pathological feature of intervertebral disc degeneration (IDD). However, the underlying mechanism of vascularization in IDD is still unclear. The current study aimed to investigate the role of AF cell derived exosome (AF-exo) in the interaction with human umbilical vein endothelial cells (HUVECs) and its potential role in the regulation of vascularization in IDD.

MAIN METHODS

Human AF tissues were obtained from patients with IDD and idiopathic scoliosis. The AF-exo were isolated and identified by transmission electron microscopy (TEM), nanoparticle trafficking analysis (NTA) and Western blotting. Then, the AF-exo were used for HUVECs cultures. The migration of HUVECs was observed in 2D and 3D cultures. The inflammatory phenotype of HUVECs was examined by Real-time PCR and enzyme-linked immunosorbent assay (ELISA). Additionally, apoptosis of HUVECs were analyzed by flow cytometry.

KEY FINDINGS

Here, we for the first time found that AF cells could secrete AF-exo and that the AF-exo could be phagocytosed by HUVECs. Additionally, we found that degenerated AF-exo exerted pro-vascularization effect on HUVECs by promoting cell migration (in 2D and 3D cultures) and inflammatory factor expression including IL-6, TNF-α, MMP-3, MMP-13 and VEGF, whereas the application of non-degenerated AF-exo demonstrated inverse effects.

SIGNIFICANCE

These results showed that AF-exo is an essential regulator mediating intercellular communication between AF cells and HUVECs, suggesting its important role in vascularization in the intervertebral disc.

Notochordal-Cell-Derived Exosomes Induced by Compressive Load Inhibit Angiogenesis via the miR-140-5p/Wnt/β-Catenin Axis

Angiogenesis is a pathological signature of intervertebral disc degeneration (IDD). Accumulating evidence has shown that notochordal cells (NCs) play an essential role in maintaining intervertebral disc development and homeostasis with inhibitive effect on blood vessel in-growth. However, the anti-angiogenesis mechanism of NCs is still unclear. In the current study, we, for the first time, isolated NC-derived exosomes (NC-exos) and showed their increased concentration following compressive load cultures. We further found that NC-exos from 0.5 MPa compressive load cultures (0.5 MPa/NC-exos) inhibit angiogenesis via transferring high expressed microRNA (miR)-140-5p to endothelial cells and regulating the downstream Wnt/β-catenin pathway. Clinical evidence showed that exosomal miR-140-5p expression of the nucleus pulposus is negatively correlated with angiogenesis in IDD. Finally, 0.5 MPa/NC-exos were demonstrated to have a therapeutical impact on the degenerated disc with an anti-angiogenesis effect in an IDD model. Consequently, our present findings provide insights into the anti-angiogenesis mechanism of NC-exos, indicating their therapeutic potential for IDD.

Exosomal circular RNA sorting mechanisms and their function in promoting or inhibiting cancer

Exosomes are nanoscale phospholipid bilayer vesicles that can be artificially engineered into vectors for the treatment of cancer. Circular RNA (circRNA), a type of non-coding RNA, has crucial regulatory functions in various aspects of cancer, such as tumorigenesis, apoptosis, proliferation, invasion, metastasis and chemo- and radiotherapeutic resistance, as well as in cancer prognosis. Notably, the exosomal transfer of circRNAs may function to both promote and inhibit cancer. Numerous studies have addressed the importance of circRNAs in cancer and non-coding RNAs (such as microRNAs and long non-coding RNAs) in exosomes. However, little research has focussed on a class of RNAs called exosomal circRNAs. The present review discusses current studies regarding exosomal circRNAs, including their biogenesis and biological functions, their abundance in exosomes and possible sorting mechanisms and their potential roles in both promoting and inhibiting cancer. It is predicted that in the next five years there will be increasing research exploring the functional mechanisms of exosomal circRNA in various diseases, in particular their roles in cancer genesis and progression.

Extracellular Vesicles as Mediators of Cellular Crosstalk Between Immune System and Kidney Graft

Extracellular vesicles (EVs) are known immune-modulators exerting a critical role in kidney transplantation (KT). EV bioactive cargo includes graft antigens, costimulatory/inhibitory molecules, cytokines, growth factors, and functional microRNAs (miRNAs) that may modulate expression of recipient cell genes. As paracrine factors, neutrophil- and macrophage-derived EVs exert immunosuppressive and immune-stimulating effects on dendritic cells, respectively. Dendritic cell-derived EVs mediate alloantigen spreading and modulate antigen presentation to T lymphocytes. At systemic level, EVs exert pleiotropic effects on complement and coagulation. Depending on their biogenesis, they can amplify complement activation or shed complement inhibitors and prevent cell lysis. Likewise, endothelial- and platelet-derived EVs can exert procoagulant/prothrombotic effects and also promote endothelial survival and angiogenesis after ischemic injury. Kidney endothelial- and tubular-derived EVs play a key role in ischemia-reperfusion injury (IRI) and during the healing process; additionally, they can trigger rejection by inducing both alloimmune and autoimmune responses. Endothelial EVs have procoagulant/pro-inflammatory effects and can release sequestered self-antigens, generating a tissue-specific autoimmunity. Renal tubule-derived EVs shuttle pro-fibrotic mediators (TGF-β and miR-21) to interstitial fibroblasts and modulate neutrophil and T-lymphocyte influx. These processes can lead to peritubular capillary rarefaction and interstitial fibrosis-tubular atrophy. Different EVs, including those from mesenchymal stromal cells (MSCs), have been employed as a therapeutic tool in experimental models of rejection and IRI. These particles protect tubular and endothelial cells (by inhibition of apoptosis and inflammation-fibrogenesis or by inducing autophagy) and stimulate tissue regeneration (by triggering angiogenesis, cell proliferation, and migration). Finally, urinary and serum EVs represent potential biomarkers for delayed graft function (DGF) and acute rejection. In conclusion, EVs sustain an intricate crosstalk between graft tissue and innate/adaptive immune systems. EVs play a major role in allorecognition, IRI, autoimmunity, and alloimmunity and are promising as biomarkers and therapeutic tools in KT.

The immune landscape of esophageal cancer

Esophageal cancer (EC) seriously threatens human health, and a promising new avenue for EC treatment involves cancer immunotherapy. To improve the efficacy of EC immunotherapy and to develop novel strategies for EC prognosis prediction or clinical treatment, understanding the immune landscapes in EC is required. EC cells harbor abundant tumor antigens, including tumor-associated antigens and neoantigens, which have the ability to initiate dendritic cell-mediated tumor-killing cytotoxic T lymphocytes in the early stage of cancer development. As EC cells battle the immune system, they obtain an ability to suppress antitumor immunity through immune checkpoints, secreted factors, and negative regulatory immune cells. Cancer-associated fibroblasts also contribute to the immune evasion of EC cells. Some factors of the immune landscape in EC tumor microenvironment are associated with cancer development, patient survival, or treatment response. Based on the immune landscape, peptide vaccines, adoptive T cell therapy, and immune checkpoint blockade can be used for EC immunotherapy. Combined strategies are required for better clinical outcome in EC. This review provides directions to design novel and effective strategies for prognosis prediction and immunotherapy in EC.