Efficient induction of a Her2-specific anti-tumor response by dendritic cells pulsed with a Hsp70L1-Her2(341-456) fusion protein

Engineered Extracellular Vesicles to Enhance Antigen Presentation for Boosting Light-Driven Tumor Immunotherapy

Extracellular vesicles (EVs) have emerged as potential tools for tumor-target therapy accompanied with activating anticancer immune responses by serving as an integrated platform, but usually suffered from the limited cross presentation of tumor-associated antigen by dendritic cells (DCs). Here, a straightforward engineering strategy to construct heat shock proteins 70 (HSP70) highly expressed EVs incapsulated with Te nanoparticles (Te@EVsHSP70 ) for tumor photothermal therapy triggering improved immunotherapy is proposed. Tumor cells are firstly used as bioreactors for intracellular synthesis of Te nanoparticles, and NIR irradiation is subsequently introduced to upregulate the expression of HSP70 to give engineered Te@EVsHSP70 through exocytosis. Te@EVsHSP70 exhibits excellent photothermal performance and enhanced tumor antigen capture capability, which induces significant immunogenic death of tumor cells and improves DCs maturation both in vitro and in vivo. Thus, the engineered EVs demonstrate superior antitumor efficacy through photothermal effect and following provoked antitumor immune responses. This work provides a facile method to fabricate multifunctional EVs-based drug delivery system for improving photothermal-triggered tumor immunotherapy.

Dendritic cells modified by tumor associated antigen SMP30 have enhanced antitumor effect against mouse hepatocarcinoma cells in vitro and in vivo

OBJECTIVES

Tumor immunotherapy based on dendritic cells (DC) is one of the most promising approaches to treat cancers. This therapy uses an immunogenic tumor antigen to present it to T cells. Senescence marker protein 30 (SMP30) is identified as a tumor associated antigen (TAA) with high immunogenicity and specificity for hepatocellular carcinoma (HCC). DCs are the most potent antigen presenting cells, and can be transduced with tumor antigens to enhance antitumor immune response. The purpose of this study was to investigate the antitumor effect of DCs transduced with a recombinant lentiviral vector (LV-SMP30) expressing SMP30.

METHODS

A recombinant lentiviral vector (LV-SMP30) expressing SMP30 was constructed and transduced into DCs. The expression of SMP30 was detected by western blot. Mouse bone marrow-derived DCs were divided into four groups: LV-SMP30 group (transduced with LV-SMP30), Protein group (co-cultured with SMP30 protein), LV group (transduced with the empty vector) and Untreated group (the normal DCs). The effect of LV-SMP30 on DCs was detected through surface markers (CD123, CD11c, CD80 and CD86) and cytokine production. The activation and proliferation of CD3⁺CD8⁺ T cells were detected by CCK-8 kit. Flow cytometry was used to detect CD3⁺CD8⁺ T cell-mediated cytotoxicity. After construction of a mouse subcutaneous xenograft model, the volume and growth of tumors in different groups were observed. The changes in serum immune indexes in the treated groups were compared with those in the control group.

RESULTS

The LV-SMP30 recombinant was constructed and transduced into DCs successfully, and LV-SMP30-transduced DCs stably expressed SMP30. The percentages of expression in the LV-SMP30 and Protein groups were significantly higher than those in the LV or Untreated groups (P<0.05). Meanwhile, after the DCs were cultured for 72 hours, the levels of IL-2, IL-6, IL-12, and IFN-γ were significantly higher in the LV-SMP30 and Protein groups than in the LV group or Untreated group (P<0.05). After the DCs were continuously cultured for one week, however, the cytokine levels in the LV-SMP30 group were significantly higher than those in the Protein group (P<0.05). In addition, CD3⁺CD8⁺ T cell proliferation and activation levels were substantially higher in the LV-SMP30 and Protein groups than in the LV or Untreated groups (P<0.05). Furthermore, as the ratio of effectors/target cells increasing in the LV-SMP30 group, CD3⁺CD8⁺ T cell-mediated cytotoxicity in H22 cells became higher (0:1, 10:1; 20:1; 40:1, respectively). In comparison to the control group, the cytotoxicity of the LV-SMP30 group was considerably increased at the ratios of 10:1, 20:1 and 40:1 (P<0.05). However, in the case of Hep1-6 cells, there was no significant difference in CD3⁺CD8⁺ T cell-mediated cytotoxicity among the groups. In addition, when compared with other groups, the mice in the LV-SMP30 group showed the most volume reduction, the slowest tumor growth, and the highest level of IL-2 and IFN-γ (P<0.05).

CONCLUSION

DCs transduced with LV-SMP30 can dramatically enhance specific CD3⁺CD8⁺ T cell immune responses against mouse hepatocarcinoma cells in vitro and in vivo. These findings lend significant support to the development of the DC-based SMP30 antigen vaccine for hepatocarcinoma immunotherapy.

Intercepting Premalignant, Preinvasive Breast Lesions Through Vaccination

Breast cancer (BC) prevention remains the ultimate cost-effective method to reduce the global burden of invasive breast cancer (IBC). To date, surgery and chemoprevention remain the main risk-reducing modalities for those with hereditary cancer syndromes, as well as high-risk non-hereditary breast lesions such as ADH, ALH, or LCIS. Ductal carcinoma in situ (DCIS) is a preinvasive malignant lesion of the breast that closely mirrors IBC and, if left untreated, develops into IBC in up to 50% of lesions. Certain high-risk patients with DCIS may have a 25% risk of developing recurrent DCIS or IBC, even after surgical resection. The development of breast cancer elicits a strong immune response, which brings to prominence the numerous advantages associated with immune-based cancer prevention over drug-based chemoprevention, supported by the success of dendritic cell vaccines targeting HER2-expressing BC. Vaccination against BC to prevent or interrupt the process of BC development remains elusive but is a viable option. Vaccination to intercept preinvasive or premalignant breast conditions may be possible by interrupting the expression pattern of various oncodrivers. Growth factors may also function as potential immune targets to prevent breast cancer progression. Furthermore, neoantigens also serve as effective targets for interception by virtue of strong immunogenicity. It is noteworthy that the immune response also needs to be strong enough to result in target lesion elimination to avoid immunoediting as it may occur in IBC arising from DCIS. Overall, if the issue of vaccine targets can be solved by interrupting premalignant lesions, there is a potential to prevent the development of IBC.

Myeloid and plasmacytoid dendritic cell combined vaccines loaded with heat-treated tumor cell lysates enhance antitumor activity in murine lung cancer

The present study aimed to investigate the efficacy of a myeloid dendritic cell (mDCs) and plasmacytoid (p)DC combined vaccine loaded with heat-treated cancer cell lysates against lung cancer cells. The mDCs and pDCs were selected using magnetic bead sorting. Antigen loading was performed by adding heat-treated Lewis lung cancer cell lysates to mDC, pDC or mDC+pDC (1:1). Surface expression of CD80, CD86, CD40 and major histocompatibility complex (MHC)-II molecules were determined using flow cytometry, and the secretion of cytokines IL-12, IL-6 and TNF-α were assessed using ELISA assays. The effect of the mDC and pDC vaccine on cytotoxic T lymphocytes (CTLs) against tumor cells was investigated. Tumor-bearing nude mice were intravenously injected with the mDC and pDC combined vaccine. Tumor tissues were collected for hematoxylin and eosin and TUNEL staining. Loading with tumor cell lysate significantly upregulated the surface expression of costimulatory molecules MHC-II on DCs and enhanced secretions of IL-6, IL-12 and TNF-α by DCs. In addition, the tumor cell lysate-loaded mDC and pDC combined vaccine significantly promoted lymphocyte proliferation and enhanced CTL-mediated cytotoxicity against Lewis lung cancer cells compared with mDC or pDC treatment alone. Furthermore, intravenous injection of the mDC and pDC combined vaccine into tumor-bearing nude mice significantly inhibited subcutaneous tumor growth and induced necrosis and apoptosis within the tumor tissue. Overall, the pDC and mDC combination vaccine loaded with heat-treated Lewis lung cancer cell lysate had a synergistic effect on the induction of T lymphocyte proliferation and antitumor efficacy, which may be associated with the upregulation of co-stimulatory molecules and cytokine secretions.

Investigation of the combination of anti-PD-L1 mAb with HER2/neu-loaded dendritic cells and QS-21 saponin adjuvant: effect against HER2 positive breast cancer in mice

BACKGROUND

Human epidermal growth factor receptor 2 (HER2) is overexpressed in a subset of cancers including 25% of breast cancers. Since combination therapy consisting of multiple therapeutic approaches is considered a promising regimen, we examined combination treatment modalities in a xenograft model in Balb/c mice injected with 4T1-HER2 cells. We used HER2/neu-loaded bone marrow-derived dendritic cells (BM-DC's) along with anti-PD-L1 monoclonal antibody in a new combination immunotherapy model.

METHODS

The combination was composed of an active immunotherapy (i.e. BM-DC-based vaccine) designed to boost the immune response against target antigen and was augmented by using anti-PD-L1 mAb to prevent immune evasion by the xenografted tumors. The vaccine combination was further supported using a QS-21 saponin adjuvant and the immune response was evaluated.

RESULTS

Mice treated with HER2/neu-loaded BM-DCs, combined with QS-21 and anti-PD-L1 mAb had significantly decreased tumor sizes and their splenocytes had enhanced cytotoxic activity, based on the lactate dehydrogenase (LDH) assay, compared to vaccine and adjuvant groups alone. The same vaccination group demonstrated a remarkable increase in IFN-γ secreting CD8+ T-cells analyzed by flow cytometry. ELISA data also revealed a significant increase in the serum anti-HER2 IgG1 response; in addition, there was significant splenocyte proliferation upon stimulation with antigen compared to vaccine and adjuvant groups. Consistently, a significant infiltration of CD4+, CD8+ immune cells in and around the tumors was observed.

CONCLUSIONS

Our data suggest that the BM-DC + HER2/neu + QS-21 + anti-PD-L1 vaccine combination paradigm synergistically generates anti-tumor activity and immune responses against HER2 overexpressing breast cancer in mice.

Intracellular HSP70L1 inhibits human dendritic cell maturation by promoting suppressive H3K27me3 and H2AK119Ub1 histone modifications

Epigenetic regulation has been attracting increasing attention due to its role in cell differentiation and behaviors. However, the epigenetic mechanisms that regulate human dendritic cell (DC) differentiation and development remain poorly understood. Our previous studies show that extracellular heat shock protein 70-like protein (HSP70L1) is a potent adjuvant of Th1 responses via stimulating DCs when released from cells; however, the role of intracellular HSP70L1 in DC differentiation and maturation remains unknown. Herein, we demonstrate that intracellular HSP70L1 inhibits human DC maturation by suppressing MHC and costimulatory molecule expression, in contrast to the adjuvant activity of extracellular HSP70L1. The stability of intracellular HSP70L1 is dependent on DNAJC2, a known epigenetic regulator. Mechanistically, intracellular HSP70L1 inhibits the recruitment of Ash1l to and maintains the repressive H3K27me3 and H2AK119Ub1 modifications on the promoter regions of costimulatory, MHC and STAT3 genes. Thus, intracellular HSP70L1 is an inhibitor of human DC maturation. Our results provide new insights into the epigenetic regulation of cell development by intracellular HSP70L1.

TCR-like antibody drug conjugates mediate killing of tumor cells with low peptide/HLA targets

The currently marketed antibody-drug conjugates (ADC) destabilize microtubule assembly in cancer cells and initiate apoptosis in patients. However, few tumor antigens (TA) are expressed at high densities on cancer lesions, potentially minimizing the therapeutic index of current ADC regimens. The peptide/human leukocyte antigen (HLA) complex can be specifically targeted by therapeutic antibodies (designated T cell receptor [TCR]-like antibodies) and adequately distinguish malignant cells, but has not been the focus of ADC development. We analyzed the killing potential of TCR-like ADCs when cross-linked to the DNA alkylating compound duocarmycin. Our data comprise proof-of-principle results that TCR-like ADCs mediate potent tumor cytotoxicity, particularly under common scenarios of low TA/HLA density, and support their continued development alongside agents that disrupt DNA replication. Additionally, TCR-like antibody ligand binding appears to play an important role in ADC functionality and should be addressed during therapy development to avoid binding patterns that negate ADC killing efficacy.

HSP70L1-mediated intracellular priming of dendritic cell vaccination induces more potent CTL response against cancer

Heat-shock protein (HSP)-based immunotherapy is established on its adjuvant effects when applied via an extracellular approach to pulse and activate dendritic cells (DCs). Our previous studies indicate that DCs pulsed with recombinant fusion proteins of antigenic fragment and HSP70-like protein 1 (HSP70L1) are potent in stimulating antigen-specific Th1 responses. We herein evaluated the cytotoxic T cell (CTL) response by an intracellular approach of priming DCs with transfection of recombinant adenovirus-expressing the fusion gene of the 576-699 fragment of carcinoembryonic antigen (CEA) and HSP70L1. As compared with DCs pulsed with extracellular fusion protein, the DCs transfected with recombinant adenovirus expressing the fusion gene displayed equivalent mature phenotypes but less inflammatory appearance. However, the transfected DCs were superior to the pulsed DCs in inducing CEA-specific CTLs. Consistently, immunization of HLA-A2.1/H-2K^b transgene mice with the transfected DCs could induce more quantities of HLA-A2.1-restricted CEA-specific CTLs, protecting nude mice more significantly from human CEA-expressing colon tumor challenge when adoptively transferred. Mechanistic investigation indicated that intracellular expression of the fusion protein empowered the transfected DCs by activation of STAT1 possibly via inducing IFN-β and ERK pathways. Therefore, the more potent ability to induce anti-CEA CTL responses enables the DCs, which transfected with recombinant adenovirus expressing the fusion gene of antigenic CEA fragment and Th1 adjuvant, as an alternative promising approach for the immunotherapy of CEA-positive tumors.

Enhanced anti-colon cancer immune responses with modified eEF2-derived peptides

Eukaryotic elongation factor-2 (eEF2) is overexpressed in many human cancers and is an attractive target for cancer immunotherapy. The eEF2 derived polypeptides have been shown to be able to induce cytotoxic T lymphocytes from healthy donor. Here, we demonstrate the evidence indicating that modification of a segment of peptides from wild type eEF2-derived immunogenic peptides is able to further enhance its capacity of inducing antigen-specific cytotoxic T lymphocytes (CTLs) against colon cancer cells. Using peptide-MHC binding algorithms, potential HLA-A2.1-restricted epitopes capable of inducing specific CD8(+) CTLs were identified. By analyzing HLA-A2.1 affinity and immunogenicity, we further identified one novel immunogenic peptide, P739-747 (RLMEPIYLV), that elicited specific CTL responses in HLA-A2.1/K(b) transgenic mice and culture with peripheral blood lymphocytes from colon cancer patients. Furthermore, replacing certain amino acids (at positions 1, 3, 7) within the P739-747 sequence improved the immunogenicity against eEF2. Several analogs containing the auxiliary HLA-A*0201 anchor residues were able to stably bind to HLA-A*0201 and enhance CTL responses compared with the native sequence; two of them showed increased anti-tumor effects during the adoptive immunotherapy in vivo. Thus, these results support that modified immunogenic analogs are promising candidates for peptide-based cancer vaccination and immunotherapy.

Dendritic Cell-Based Cancer Immunotherapy against Multiple Myeloma: From Bench to Clinic

Although the introduction of stem cell transplantation and novel agents has improved survival, multiple myeloma (MM) is still difficult to cure. Alternative approaches are clearly needed to prolong the survival of patients with MM. Dendritic cell (DC) therapy is a very promising tool immunologically in MM. We developed a method to generate potent DCs with increased Th1 polarization and migration ability for inducing strong myeloma-specific cytotoxic T lymphocytes. In this review, we discuss how the efficacy of cancer immunotherapy using DCs can be improved in MM.

TLR4 is essential for dendritic cell activation and anti-tumor T-cell response enhancement by DAMPs released from chemically stressed cancer cells

The combination of immunotherapy and chemotherapy is regarded as a promising approach for the treatment of certain types of cancer. However, the underlying mechanisms need to be fully investigated to guide the design of more efficient protocols for cancer chemoimmunotherapy. It is well known that danger-associated molecular patterns (DAMPs) can activate immune cells, including dendritic cells (DCs), via Toll-like receptors (TLRs); however, the role of DAMPs released from chemical drug-treated tumor cells in the activation of the immune response needs to be further elucidated. Here, we found that colorectal cancer (CRC) cells treated with oxaliplatin (OXA) and/or 5-fluorouracil (5-Fu) released high levels of high-mobility group box 1 (HMGB1) and heat shock protein 70 (HSP70). After OXA/5-Fu therapy, the sera of CRC patients also exhibited increased levels of HMGB1 and HSP70, both of which are well-known DAMPs. The supernatants of dying CRC cells treated with OXA/5-Fu promoted mouse and human DC maturation, with upregulation of HLA-DR, CD80 and CD86 expression and enhancement of IL-1β, TNF-α, MIP-1α, MIP-1β, RANTES and IP-10 production. Vaccines composed of DCs pulsed with the supernatants of chemically stressed CRC cells induced a more significant IFN-γ-producing Th1 response both in vitro and in vivo. However, the supernatants of chemically stressed CRC cells failed to induce phenotypic maturation and cytokine production in TLR4-deficient DCs, indicating an essential role of TLR4 in DAMP-induced DC maturation and activation. Furthermore, pulsing with the supernatants of chemically stressed CRC cells did not efficiently induce an IFN-γ-producing Th1 response in TLR4-deficient DCs. Collectively, these results demonstrate that DAMPs released from chemically stressed cancer cells can activate DCs via TLR4 and enhance the induction of an anti-tumor T-cell immune response, delineating a clinically relevant immuno-adjuvant pathway triggered by DAMPs.