Exosomes Isolated from Ascites of T-Cell Lymphoma-Bearing Mice Expressing Surface CD24 and HSP-90 Induce a Tumor-Specific Immune Response

Abstract

Extracellular vesicles (EVs), including endosome-derived nanovesicles (exosomes), are involved in cell–cell communication. Through transfer of their molecular contents, extracellular nanovesicles can alter the function of recipient cells. Due to these characteristics, EVs have shown potential as a new alternative for cancer immunotherapy. Tumor exosomes isolated from malignant ascites can activate dendritic cells, thereby priming the immune system to recognize and kill cancer cells. However, a suppressive role on tumor immune response has also been reported, suggesting that the neoplastic stage of carcinogenesis and the microenvironment where tumor cells grow may influence the amount of EVs released by the cell. This neoplastic stage and microenvironment may also impact EVs’ components such as proteins and miRNA, determining their biological behavior. Most T-cell lymphomas have an aggressive clinical course and poor prognosis. Consequently, complementary alternative therapies are needed to improve the survival rates achieved with conventional treatments. In this work, we have characterized EVs isolated from ascites of mice bearing a very aggressive murine T-cell lymphoma and have studied their immunogenic properties. Small EVs were isolated by differential centrifugation, ultrafiltration, and ultracentrifugation at 100,000 × g on a sucrose cushion. The EVs were defined as exosomes by their morphology and size analyzed by electron microscopy, their floating density on a sucrose gradient, as well as their expression of endosome marker proteins ALIX, TSG-101; the tetraspanins CD63, CD9, and CD81. In addition, they contain tumor antigens, the marker for malignancy CD24, the heat shock protein HSP-70, and an unusual surface expression of HSP-90 was demonstrated. The administration of EVs isolated from ascites (EVs A) into naïve-syngeneic mice induced both humoral and cellular immune responses that allowed the rejection of subsequent tumor challenges. However, the immunization had no effect on a non-related mammary adenocarcinoma, demonstrating that the immune response elicited was specific and also it induced immune memory. In vitro analysis demonstrated that T-cells from EVs A-immunized mice secrete IFN-γ in response to tumor stimulation. Furthermore, tumor-specific CD4+ and CD8+ IFN-γ secreting cells could be efficiently expanded from mice immunized with EVs A, showing that a T helper 1 response is involved in tumor rejection. Our findings confirm exosomes as promising defined acellular tumor antigens for the development of an antitumor vaccine.

Exosomes from heat‐stressed tumour cells inhibit tumour growth by converting regulatory T cells to Th17 cells via IL‐6

“…DC‐derived exosomes can also promote activation and proliferation of natural killer cells through natural killer group 2D ligands and interleukin (IL)‐15 receptor subunit alpha . In addition, exosomes isolated from ascites of T cell lymphoma‐bearing mice expressing surface CD24 and heat shock protein (HSP)90 can induce a tumour‐specific immune response . Therefore, exosomes can be considered nanoscale cancer vaccines…”

“…4 In addition, exosomes isolated from ascites of T cell lymphoma-bearing mice expressing surface CD24 and heat shock protein (HSP)90 can induce a tumour-specific immune response. 5 Therefore, exosomes can be considered nanoscale cancer vaccines. 6 It has been demonstrated that exosomes exhibit greater antitumour effects when artificially modified.…”

Enhancement of Anti-Leukemia Immunity by Leukemia–Derived Exosomes Via Downregulation of TGF-β1 Expression

“…Recently, exosome-based immunotherapy has generated considerable attention [2, 3], because it offers potential as a novel tumor vaccine to effectively eliminate minimal residual disease (MRD), thus prolonging DFS. It has been reported that most tumor cells constitutively secret exosomes and furthermore, the exosomes derived from tumor cells (TEXs) are highly enriched in tumor associated antigens (TAA) and in a series of immune-related proteins such as histocompatibility complex (MHC) molecules and heat shock proteins (HSPs) [4, 5].…”

Hydrogen Peroxide Stimulates Exosomal Cathepsin B Regulation of the Receptor for Advanced Glycation End‐Products (RAGE)

“…Exosomes serve as vehicles for cell‐to‐cell communication, notably spanning a wide range of distances, in which cargo (e.g., nucleic acids, proteins, prions, etc …) modulate recipient cells [Jella et al, ]. The composition of the exosome varies depending upon cell type and context, and multiple studies converge to illustrate that exosomes affect cell function [Lang et al, ; Menay et al, ; Wang et al, ; Zhang et al, ]. The role of exosomes in health and disease is just beginning to be better understood.…”

“…modulate recipient cells [Jella et al, 2016]. The composition of the exosome varies depending upon cell type and context, and multiple studies converge to illustrate that exosomes affect cell function [Lang et al, 2017;Menay et al, 2017;Wang et al, 2017;Zhang et al, 2017]. The role of exosomes in health and disease is just beginning to be better understood.…”