Bone marrow-derived dendritic cells pulsed with tumor lysates induce anti-tumor immunity against gastric cancer ex vivo

Boosting immunotherapy efficacy: Empowering the Potency of Dendritic cells loaded with breast cancer lysates through CTLA-4 suppression

Anticancer immunotherapies with a dendritic Cell (DC) basis are becoming more popular. However, it has been suggested that the tumor's immunosuppressive mechanisms, such as inhibitory immunological checkpoint molecules, reduce the effectiveness of anticancer immunogenicity mediated by DC. Thus, overcoming immune checkpoints and inducing effective antigen-specific T-cell responses uniquely produced with malignant cells represent the key challenges. Among the inhibitory immune checkpoints, DCs' ability to mature and present antigens is decreased by CTLA-4 expression. Consequently, we hypothesized that by expressing CTLA-4 cells on DCs, the T cells' activation against tumor antigens would be suppressed when confronted with these antigens presented by DCs. In this research, by loading cell lysate of breast cancer (BC) on DCs and the other hand by inhibiting the induction of CTLA-4 using small interfering RNA (siRNA), we assessed the functional activities and phenotypes of DCs, and also the responses associated with T-cells following co-culture DC/T cell. Our research has shown that the suppression of CTLA-4 enhanced the stimulating capabilities of DCs. Additionally, CTLA-4-suppressed BC cell lysate-loaded DCs produced more IL-4 and IFN-ϒ and increased T cell induction in contrast to DCs without CTLA-4 suppression. Together, our data point to CTLA-4-suppressed DCs loaded with BC cell lysate as a potentially effective treatment method. However, further research is required before employing this method in therapeutic contexts.

Suppression of murine tumour growth through CD8+ cytotoxic T lymphocytes via activated DEC-205+ dendritic cells by sequential administration of α-galactosylceramide in vivo

Cancer immunity is mediated through the effective priming and activation of tumour‐specific class I MHC molecule‐restricted CD8⁺ cytotoxic T lymphocytes (CTLs). DEC‐205⁺ dendritic cells (DCs) can cross‐present the epitope(s) of captured tumour antigens associated with class I MHC molecules alongside co‐stimulatory molecules to prime and activate tumour‐specific CD8⁺CTLs. Immunosuppressive tolerogenic DCs with reduced co‐stimulatory molecules may be a cause of impaired CTL induction. Hepa1‐6‐1 cells were established from the mouse hepatoma cell line Hepa1‐6; these cells grow continuously after subcutaneous implantation into syngeneic C57BL/6 (B6) mice and do not prime CD8⁺CTLs. In this study, we show that the growth of ongoing tumours was suppressed by activated CD8⁺CTLs with tumour‐specific cytotoxicity through the administration of the glycolipid α‐galactosylceramide (α‐GalCer), which is a compound known to stimulate invariant natural killer T (iNKT) cells and selectively activate DEC‐205⁺DCs. Moreover, we demonstrated that sequential repetitive intraperitoneal inoculation with α‐GalCer every 48 hr appeared to convert tolerogenic DEC‐205⁺DCs into immunogenic DCs with a higher expression of co‐stimulatory molecules and a stronger cross‐presentation capacity, which primed CTL precursors and induced tumour‐specific CD8⁺CTLs within the tumour environment without activating iNKT cells. These findings provide a new basis for cancer immunotherapy to convert tolerogenic DEC‐205⁺DCs within tumours into immunogenic DCs through the sequential administration of an immuno‐potent lipid/glycolipid, and then activated immunogenic DCs with sufficient expression of co‐stimulatory molecules prime and activate tumour‐specific CD8⁺CTLs within the tumour to control tumour growth.

Immune oppression array elucidating immune escape and survival mechanisms in uveal melanoma

AIM

To examine the genetic profile of primary uveal melanoma (UM) as compared to UM in immune escape.

METHODS

Dendritic cells (DC) loaded with lysates of UM cells of high metastatic potential were used to stimulate CTLs(CTLs). When CTLs co-cultured with the UM cells, most UM cells could be eliminated. Survival UM cells grew slowly and were considered to be survival variants and examined by a microarray analysis. These differential genes were analyzed further with Venn Diagrams and functions related to immune escape. We additionally examined transcriptional changes of manually selected survival variants of UM cells and of clinical UM samples by quantitative real-time polymerase chain reaction (qRT-PCR), and analyzed the correlation of these expressions and patients' survival.

RESULTS

Gene expression analyses revealed a marked up-regulation of SLAMF7 and CCL22 and a significant down-regulation of KRT10, FXYD3 and ABCC2. The expression of these genes in the relapsed UM was significantly greater than those in primary UM. UM patients with overexpression of these genes had a shorter survival period as compared with those of their underexpression.

CONCLUSION

Gene expression, in particular of SLAMF7, CCL22, KRT10, FXYD3 and ABCC2, differed between primary UM cells and survival variants of UM cells.

Phenotypic and functional comparison of two distinct subsets of programmable cell of monocytic origin (PCMOs)-derived dendritic cells with conventional monocyte-derived dendritic cells

Dendritic cells (DCs) are professional antigen-presenting cells with the ability to induce primary T-cell responses. They are commonly produced by culturing monocytes in the presence of IL-4 and GM-CSF (cells produced in this manner are called conventional DCs). Here we report the generation of two functionally distinct subsets of DCs derived from programmable cells of monocytic origin (PCMOs) in the presence of IL-3 or tumor necrosis factor alpha (TNF-α). Monocytes were treated with macrophage colony-stimulating factor (M-CSF) and IL-3 for 6 days and then incubated with IL-4 and IL-3 (for IL-3 DCs) or with IL-4, GM-CSF and TNF-α (for TNF-α DCs) for 7 days. Monocytes were then loaded with tumor lysate (used as antigen), and poly (I∶C) was added. The maturation factors TNF-α and monocyte conditioned medium (MCM) were added on days 4 and 5, respectively. The phenotypes of the DCs generated were characterized by flow cytometry, and the cells' phagocytic activities were measured using FITC-conjugated latex bead uptake. T-cell proliferation and cytokine release were assayed using MTT and commercially available ELISA kits, respectively. We found that either IL-3DCs or TNF-α DCs induce T-cell proliferation and cytokine secretion; the cytokine release pattern showed reduced IL-12/IL-10 and IFN-γ/IL-4 ratios in both types of DCs and in DC-primed T-cell supernatant, respectively, which confirmed that the primed T cells were polarized toward aTh2-type immune response. We concluded that PCMOs are a new cell source that can develop into two functionally distinct DCs that both induce a Th2-type response in vitro. This modality can be used as a DC-based immunotherapy for autoimmune diseases.

A clinical study of weining granules in the treatment of gastric precancerous lesions

OBJECTIVE

To investigate the clinical effects of Weining granules on gastric precancerous lesions (GPLs).

METHODS

120 patients with GPLs were randomly assigned in a 1:1 ratio to receive Weining granules (trial group) or the comparator Weifuchun tablets (control group) for 6 months. Outcomes were compared between the two groups including: overall response; gastroscopically-determined response; pathologically-confirmed response; eradication of Helicobacter pylori (HP); microvessel density (MVD) in the gastric mucosa; expression of vascular endothelial growth factor (VEGF); interleukin 2 (IL-2); interleukin 6 (IL-6); T lymphocyte subsets; immunoglobulins; symptom scores; quality of life (QOL); and adverse reactions.

RESULTS

Patients in the trial group had a significantly higher (P < 0.05) overall response rate (81.7%) as compared with those in the control group (63.3%). Relative to treatment with Weifuchun tablets treatment with Weining granules resulted in a significant improvement (P < 0.05) in the scores for gastric pain, distension and stuffiness in the hypochondrium, and anorexia. As compared with the tablets the granules were associated with a significantly higher overall gastroscopically-determined response rate (78.3%; P < 0.05). Pathological examination of tissue samples indicated that 61.7% of patients receiving the granules were cured with an overall response rate of 75.5%; these rates were significantly higher than in the control group (P < 0.05). In comparison with patients receiving the tablets, those given the granules were significantly more likely to have their HP eradicated (75.0% vs. 51.4%; P < 0.05). Improvements in MVD, VEGF, CD4+, CD4+/ CD8+, IL-2, IL-6 and IgG were significantly greater with the Weining Granules than with the Weifuchun tablets (P < 0.05 or P < 0.01). After follow-up of 1 year, 17.5% of patients in the trial group relapsed as compared with 39.5% in the control group (P < 0.05). Relative to the control group, the trial group showed significantly greater improvements in physical, psychological and social relationships, and in environmental domains (P < 0.05 or P < 0.01). No significant adverse reactions were observed during treatment.

CONCLUSION

The Weining granules appear to be effective in improving the gastric precancerous state and the main symptoms, in inhibiting angiogenesis, enhancing immune function and QOL, and in reducing 1-year relapses. In addition, this preparation seems to be associated with a low risk of adverse events, making it a safe and efficacious option for the treatment of GPLs.

Lentinan enhances the efficacy of the DCF regimen in patients with advanced gastric cancer: an analysis of 40 cases

AIM: To evaluate whether lentinan enhances the curative effects of the DCF (docetaxel, cisplatin and fluorouracil) regimen in patients with advanced gastric cancer.

METHODS: Eighty patients with stages III and IV gastric cancer who were treated at our hospital between January 2007 and December 2008 were randomly divided into two groups to receive DCF chemotherapy alone or DCF chemotherapy in combination with lentinan. The curative effects, routine blood parameters, lymphocyte subsets and quality of life were compared between the two groups.

RESULTS: The disease control rate was significantly higher in the lentinan plus DCF group than in the DCF group (87.5% vs 75.0%, P < 0.05), while the incidence of side effects (including neutropenia, leukopenia, anemia, thrombocytopenia and infection) was significantly lower in the lentinan plus DCF group than in the DCF group (P < 0.05). No significant differences were noted in routine blood parameters, lymphocyte subsets and quality of life before chemotherapy between the two groups (all P > 0.05). After chemotherapy, the numbers of WBC, lymphocytes, CD3⁺, CD4⁺, CD8⁺, NK cells and quality of life were significantly improved in the lentinan plus DCF group compared to the DCF group (all P < 0.05).

CONCLUSION: Lentinan significantly enhanced the efficacy and safety of the DCF regimen in patients with advanced gastric cancer.

CCL3 and CCL20-recruited dendritic cells modified by melanoma antigen gene-1 induce anti-tumor immunity against gastric cancer ex vivo and in vivo

BACKGROUND

To investigate whether dendritic cell (DC) precursors, recruited by injection of chemokine ligand 3 (CCL3) and CCL20, induce anti-tumor immunity against gastric cancer induced by a DC vaccine expressing melanoma antigen gene-1 (MAGE-1) ex vivo and in vivo.

METHODS

B6 mice were injected with CCL3 and CCL20 via the tail vein. Freshly isolated F4/80-B220-CD11c+ cells cultured with cytokines were analyzed by phenotype analysis and mixed lymphocyte reaction (MLR). For adenoviral (Ad)-mediated gene transduction, cultured F4/80-B220-CD11c+ cells were incubated with Ad-MAGE-1. Vaccination of stimulated DC induced T lymphocytes. The killing effect of these T cells against gastric carcinoma cells was assayed by MTT. INF-gamma production was determined with an INF-gamma ELISA kit. In the solid tumor and metastases model, DC-based vaccines were used for immunization after challenge with MFC cells. Tumor size, survival of mice, and number of pulmonary metastatic foci were used to assess the therapeutic effect of DC vaccines.

RESULTS

F4/80-B220-CD11c+ cell numbers increased after CCL3 and CCL20 injection. Freshly isolated F4/80-B220-CD11c+ cells cultured with cytokines were phenotyically identical to typical DC and gained the capacity to stimulate allogeneic T cells. These DCs were transduced with Ad-MAGE-1, which were prepared for DC vaccines expressing tumor antigen. T lymphocytes stimulated by DCs transduced with Ad-MAGE-1 exhibited specific killing effects on gastric carcinoma cells and produced high levels of INF-gamma ex vivo. In vivo, tumor sizes of the experimental group were much smaller than both the positive control group and the negative control groups (P < 0.05). Kaplan-Meier survival curves showed that survival of the experimental group mice was significantly longer than the control groups (P < 0.05). In addition, MAGE-1-transduced DCs were also a therapeutic benefit on an established metastatic tumor, resulting in a tremendous decrease in the number of pulmonary metastatic foci.

CONCLUSIONS

CCL3 and CCL20-recruited DCs modified by adenovirus-trasnsduced, tumor-associated antigen, MAGE-1, can stimulate anti-tumor immunity specific to gastric cancer ex vivo and in vivo. This system may prove to be an efficient strategy for anti-tumor immunotherapy.

Tumor cell lysate-pulsed dendritic cells induce a T cell response against colon cancer in vitro and in vivo

To investigate whether tumor cell lysate-pulsed (TP) dendritic cells (DCs) induce cytotoxic T lymphocyte (CTL) activity against colon cancer in vitro and in vivo. Hematopoietic progenitor cells were magnetically isolated from BALB/c mice bone marrow cells. These cells were cultured with cytokines GM-CSF, IL-4, and TNFalpha to induce their maturation. They were analyzed by morphological observation and phenotype analysis. DCs were pulsed with tumor cell lysate obtained by rapid freezing and thawing at a 1:3 DC:tumor cell ratio. CTL activity and interferon gamma (IFNgamma) secretion was evaluated ex vivo. In order to determine whether or not vaccination with CT26 TP DCs induce the therapeutic potential in the established colon tumor model, CT26 colon tumor cells were implanted subcutaneously (s.c.) in the midflank of naïve BALB/c mice. Tumor-bearing mice were injected with vaccination with CT26 TP DCs on days 3 and 10. Tumor growth was assessed every 2-3 days. Finally, CTL activity and IFNgamma secretion were evaluated in immunized mice. Hematopoietic progenitor cells from mice bone marrow cells cultured with cytokines for 8 days showed the character of typical mature DCs. Morphologically, these cells were large with oval or irregularly shaped nuclei and with many small dendrites. Phenotypically, FACS analysis showed that they expressed high levels of MHC II, CD11b, CD80, and CD86 antigen, and were negative for CD8alpha. However, immature DCs cultured with cytokines for 5 days did not have typical DCs phenotypic markers. Ex vivo primed T cells with CT26 TP DCs were able to induce effective CTL activity against CT26 tumor cells, but not B16 tumor cells (E:T = 100:1, 60.36 +/- 7.11% specific lysis in CT26 group vs. 17.36 +/- 4.10% specific lysis in B16 group), and produced higher levels of IFNgamma when stimulated with CT26 tumor cells but not when stimulated with B16 tumor cells (1210.33 +/- 72.15 pg/ml in CT26 group vs. 182.25 +/- 25.51 pg/ml in B16 group, P < 0.01). Vaccination with CT26 TP DCs could induce anti-tumor immunity against CT26 colon tumor in murine therapeutic models (tumor volume on day 19: CT26 TP DCs 342 +/- 55 mm(3) vs. the other control groups, P < 0.05). In addition, all splenic CD3(+) T cells obtained from mice vaccinated with CT26 TP DCs produced high levels of IFNgamma and shown specific cytotoxic activity against CT26 tumor cells, but no cytotoxic activity when stimulated with B16 tumor cells. Tumor cell lysate-pulsed DCs can induce tumor-specific CTL activity against colon cancer in vitro and in vivo.