IL-12 improves the anti-HCC efficacy of dendritic cells loaded with exosomes from overexpressing Rab27a tumor cells.

Determining the appropriate source of antigens for optimal antigen presentation to T cells is a major challenge in designing dendritic cell (DC) -based therapeutic strategies against hepatocellular carcinoma (HCC). Tumor-derived exosomes (Tex) express a wide range of tumor antigens, making them a promising source of antigens for DC vaccines. As reported, the exosomes secreted by tumor cells can inhibit the antitumor function of immune cells. In this study, we transfected hepatocellular carcinoma cells with Rab27a to enhance the yield of exosomes, which were characterized using transmission electron microscopy and Western blot analysis. We found that Tex secreted by overexpressing Rab27a Hepatocellular carcinoma cell lines pulsed DC is beneficial for the differentiation and maturation of DCs but inhibits the secretion of the IL-12 cytokine. Consequently, we developed a complementary immunotherapy approach by using Tex as an antigen loaded onto DCs, in combination with the cytokine IL-12 to induce antigen-specific cytotoxic T lymphocytes （CTLs）. The results indicated that the combination of DC-Tex and IL-12 was more effective in stimulating T lymphocyte proliferation, releasing IFN-γ， and enhancing cytotoxicity compared to using exosomes or IL-12 alone. Additionally, the inclusion of IL-12 also compensated for the reduced IL-2 secretion by DCs caused by Tex. Moreover, in a BALB/c nude mice model of hepatocellular carcinoma, CTLs induced by DC-Tex combined with IL-12 maximized the tumor-specific T-cell immune effect and suppressed tumor growth. Thus, Tex provides a novel and promising source of antigens, with cytokines compensating for the shortcomings of Tex as a tumor antigen. This work helps to clarify the role of exosomes in tumor immunotherapy and may offer a safe and effective prospective strategy for the clinical application of exosome-based cellular immunotherapy.

Li J ，Lin W ，Huang T ，Chen M ，Lin Q ... -  《-》

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

Minimal residual leukemia cells (MRLs) are difficult to eradicate through traditional treatment and therefore remain to be a major threat to the long-term survival of leukemia patients. Tumor-derived exosomes (TEXs), which carry tumor associated antigens (TAA), may be a potential cell-free tumor vaccine for the specific eradication of MRLs. However, TEXs are intended to be less immunogenic due to exosomal TGF-β1. To further optimize the efficacy of TEX-based vaccines, we investigated whether exosomes from TGF-β1 silenced leukemia cells (LEXTGF-β1si) had an increased potential to induce a specific antitumor effect compared with non-modified exosomes. Exosomal TGF-β1 was downregulated via lentiviral shRNA silencing of TGF-β1 in leukemia cells. The characteristics of LEXTGF-β1si were determined via electron microscopy, western blot analysis, and flow cytometry. The antitumor effect of LEXTGF-β1si was evaluated by detecting the properties of LEXTGF-β1si-pulsed dendritic cells (DCs), CD4+ T-cell proliferation, Th1 cytokine secretion, specific CTL activity, and NK cell function. Moreover, to verify the superiority of LEXTGF-β1si immunization, LEXTGF-β1si was subcutaneously injected into DBA/2 mice: either followed by tumor challenge or tumor bearing. The lentiviral shRNA silencing of TGF-β1 in parental leukemia cells successfully downregulated the TGF-β1 level in leukemia cell derived exosomes (LEX). LEXTGF-β1si was uptaken by DCs and was more potent in promoting DC function by upregulating the surface expression of costimulatory factors and MHC class II molecules, while inducing the secretion of IL-12p70 and TNF-α. Furthermore, immunization with LEXTGF-β1si facilitated CD4+ T-cell proliferation and Th1 cytokine secretion, and stimulated stronger specific cytotoxic lymphocyte (CTL) response and nature killer (NK) cell cytotoxicity more efficiently compared to non-modified LEX. In mice models, immunization with LEXTGF-β1si resulted in a more potent capability to inhibit tumor growth and to prolong survival, suggesting that LEXTGF-β1si was more effective in both protective and therapeutic antitumor tests than non-modified LEX. These data suggested that down-regulation of exosomal TGF-β1 effectively induced potent anti-tumor immunity. Our strategy of optimizing exosome vaccine may have promising potential for leukemia immunotherapy.

Huang F ，Wan J ，Hu W ，Hao S ... -  《-》

HCC-derived exosomes elicit HCC progression and recurrence by epithelial-mesenchymal transition through MAPK/ERK signalling pathway.

Chen L ，Guo P ，He Y ，Chen Z ，Chen L ，Luo Y ，Qi L ，Liu Y ，Wu Q ，Cui Y ，Fang F ，Zhang X ，Song T ，Guo H ... -  《Cell Death & Disease》

alpha-fetoprotein and interleukin-18 gene-modified dendritic cells effectively stimulate specific type-1 CD4- and CD8-mediated T-Cell response from hepatocellular carcinoma patients in Vitro.

Cao DY ，Yang JY ，Dou KF ，Ma LY ，Teng ZH ... -  《HUMAN IMMUNOLOGY》

Dendritic cells-mediated CTLs targeting hepatocellular carcinoma stem cells.

Sun JC ，Pan K ，Chen MS ，Wang QJ ，Wang H ，Ma HQ ，Li YQ ，Liang XT ，Li JJ ，Zhao JJ ，Chen YB ，Pang XH ，Liu WL ，Cao Y ，Guan XY ，Lian QZ ，Xia JC ... -  《-》