Human dendritic cells engineered to express alpha tumor necrosis factor maintain cellular maturation and T-cell stimulation capacity

Novel EXO-T vaccine using polyclonal CD4+ T cells armed with HER2-specific exosomes for HER2-positive breast cancer

Breast cancer is the leading cause of death in women globally. The human epidermal growth factor receptor 2 (HER2)-positive breast cancer is often associated with poor prognosis and high mortality. Even though anti-HER2 monoclonal antibodies have improved the clinical outcome, resistance to the antibody therapy becomes a major obstacle in the treatment of HER2-positive breast cancer patients. Alternative approaches are therefore needed. HER2-specific vaccines have been developed to trigger patient’s immune system against HER2-positive breast cancer. This article describes the development of novel HER2-specific exosome (EXO)-T vaccine using polyclonal CD4⁺ T cells armed with HER2-specific dendritic cell-released EXO and demonstrates its therapeutic effect against HER2-positive tumor in double-transgenic HER2/HLA-A2 mice with HER2-specific self-immune tolerance. Therefore, our novel HER2-specific EXO-T vaccines are likely to assist in the treatment of HER2-positive breast cancer patients.

Gene-modified dendritic cell vaccines for cancer

Dendritic cell (DC) vaccines are an immunotherapeutic approach to cancer treatment that use the antigen-presentation machinery of DCs to activate an endogenous anti-tumor response. In this treatment strategy, DCs are cultured ex vivo, exposed to tumor antigens and administered to the patient. The ex vivo culturing provides a unique and powerful opportunity to modify and enhance the DCs. As such, a variety of genetic engineering approaches have been employed to optimize DC vaccines, including the introduction of messenger RNA and small interfering RNA, viral gene transduction, and even fusion with whole tumor cells. In general, these modifications aim to improve targeting, enhance immunogenicity, and reduce susceptibility to the immunosuppressive tumor microenvironment. It has been demonstrated that several of these modifications can be employed in tandem, allowing for fine-tuning and optimization of the DC vaccine across multiple metrics. Thus, the application of genetic engineering techniques to the dendritic cell vaccine platform has the potential to greatly enhance its efficacy in the clinic.

In vitro and in vivo studies of the immunomodulatory effect of Echinacea purpurea on dendritic cells

BACKGROUND

Extracts of Echinacea have been used traditionally for the treatment of diverse types of infections and wounds. They have become very familiar immunostimulant herbal medicine. However, the specific immunomodulatory effect of Echinacea remains to be elucidated.

AIM

In our study, the effect of Echinacea purpurea extract on the generation of immature DCs from monocytes was described, as well as its effect on DC differentiation. In addition, an in vivo experiment was conducted to investigate whether treatment of mice with extracts derived from E. purpurea has immunomodulatory effect on murine splenic DCs.

METHODS

Immature DCs were generated by incubating peripheral blood monocytes with cytokine cocktail (GM-CSF + IL-4) and matured by tumor necrosis factor-α (TNF-α). The cells were randomized to 5 groups to investigate E. purpurea effect in different stages. Phenotypic analysis of cell marker CD83-expressed on DCs was performed by flow cytometry. Mice were randomly divided into 3 groups; control, E. purpurea treated and E. purpurea-TNF-α treated group. The murine splenic DCs were isolated and phenotyped for CD83 and CD11c by flow cytometry.

RESULTS

Treatment of monocytes with E. purpurea prior to addition of the maturation factor TNF-α resulted in a significant decrease in the yield of DC expressing CD83. On the other hand, immature DCs generated in the culture in the presence of GM-CSF and IL-4, when treated simultaneously with E. purpurea and TNF-α, exhibited an insignificant change in the yield of CD83-expressing DCs compared with untreated control. The in vivo experiments showed that splenic DCs obtained from mice treated with E. purpurea with or without TNF-α did not exhibit significant changes in CD83 or CD11c compared with those obtained from control mice.

CONCLUSION

Our findings suggest that the immunomodulatory mechanisms of E. purpurea impact generation fate of DCs rather than differentiation stages. The results obtained in the in vivo study utilizing murine splenic DCs supported those observed in vitro.

GP120-specific exosome-targeted T cell-based vaccine capable of stimulating DC- and CD4(+) T-independent CTL responses

The limitations of highly active anti-retroviral therapy (HAART) have necessitated the development of alternative therapeutics. In this study, we generated ovalbumin (OVA)-pulsed and pcDNAgp120-transfected dendritic cell (DC)-released exosomes (EXOova and EXOgp120) and ConA-stimulated C57BL/6 CD8(+) T cells. OVA- and Gp120-Texo vaccines were generated from CD8(+) T cells with uptake of EXOova and EXOgp120, respectively. We demonstrate that OVA-Texo stimulates in vitro and in vivo OVA-specific CD4(+) and CD8(+) cytotoxic T lymphocyte (CTL) responses leading to long-term immunity against OVA-expressing BL6-10(OVA) melanoma. Interestingly, CD8(+) T cell responses are DC and CD4(+) T cell independent. Importantly, Gp120-Texo also stimulates Gp120-specific CTL responses and long-term immunity against Gp120-expressing B16 melanoma. Therefore, this novel HIV-1-specific EXO-targeted Gp120-Texo vaccine may be useful in induction of efficient CTL responses in AIDS patients with DC dysfunction and CD4(+) T cell deficiency.

Generation in vivo of peptide-specific cytotoxic T cells and presence of regulatory T cells during vaccination with hTERT (class I and II) peptide-pulsed DCs

Background

Optimal techniques for DC generation for immunotherapy in cancer are yet to be established. Study aims were to evaluate: (i) DC activation/maturation milieu (TNF-α +/- IFN-α) and its effects on CD8+ hTERT-specific T cell responses to class I epitopes (p540 or p865), (ii) CD8+ hTERT-specific T cell responses elicited by vaccination with class I alone or both class I and II epitope (p766 and p672)-pulsed DCs, prepared without IFN-α, (iii) association between circulating T regulatory cells (Tregs) and clinical responses.

Methods

Autologous DCs were generated from 10 patients (HLA-0201) with advanced cancer by culturing CD14+ blood monocytes in the presence of GM-CSF and IL-4 supplemented with TNF-α [DCT] or TNF-α and IFN-α [DCTI]. The capacity of the DCs to induce functional CD8+ T cell responses to hTERT HLA-0201 restricted nonapeptides was assessed by MHC tetramer binding and peptide-specific cytotoxicity. Each DC preparation (DCT or DCTI) was pulsed with only one type of hTERT peptide (p540 or p865) and both preparations were injected into separate lymph node draining regions every 2–3 weeks. This vaccination design enabled comparison of efficacy between DCT and DCTI in generating hTERT peptide specific CD8+ T cells and comparison of class I hTERT peptide (p540 or p865)-loaded DCT with or without class II cognate help (p766 and p672) in 6 patients. T regulatory cells were evaluated in 8 patients.

Results

(i) DCTIs and DCTs, pulsed with hTERT peptides, were comparable (p = 0.45, t-test) in inducing peptide-specific CD8+ T cell responses. (ii) Class II cognate help, significantly enhanced (p < 0.05, t-test) peptide-specific CD8+T cell responses, compared with class I pulsed DCs alone. (iii) Clinical responders had significantly lower (p < 0.05, Mann-Whitney U test) T regs, compared with non-responders. 4/16 patients experienced partial but transient clinical responses during vaccination. Vaccination was well tolerated with minimal toxicity.

Conclusion

Addition of IFN-α to ex vivo monocyte-derived DCs, did not significantly enhance peptide-specific T cell responses in vivo, compared with TNF-α alone. Class II cognate help significantly augments peptide-specific T cell responses. Clinically favourable responses were seen in patients with low levels of circulating T regs.

Dendritic cell-based human immunodeficiency virus vaccine

Dendritic cells (DC) have profound abilities to induce and coordinate T-cell immunity. This makes them ideal biological agents for use in immunotherapeutic strategies to augment T-cell immunity to HIV infection. Current clinical trials are administering DC-HIV antigen preparations carried out ex vivo as proof of principle that DC immunotherapy is safe and efficacious in HIV-infected patients. These trials are largely dependent on preclinical studies that will provide knowledge and guidance about the types of DC, form of HIV antigen, method of DC maturation, route of DC administration, measures of anti-HIV immune function and ultimately control of HIV replication. Additionally, promising immunotherapy approaches are being developed based on targeting of DC with HIV antigens in vivo. The objective is to define a safe and effective strategy for enhancing control of HIV infection in patients undergoing antiretroviral therapy.

In-vitro activation of cytotoxic T lymphocytes by fusion of mouse hepatocellular carcinoma cells and lymphotactin gene-modified dendritic cells

AIM

To investigate the in-vitro activation of cytotoxic T lymphocytes (CTLs) by fusion of mouse hepatocellular carcinoma (HCC) cells and lymphotactin gene-modified dendritic cells (DCs).

METHODS

Lymphotactin gene modified DCs (DCLptn) were prepared by lymphotactin recombinant adenovirus transduction of mature DCs which differentiated from mouse bone marrow cells by stimulation with granulocyte/macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4) and tumor necrosis factor alpha (TNF-alpha). DCLptn and H22 fusion was prepared using 50% PEG. Lymphotactin gene and protein expression levels were measured by RT-PCR and ELISA, respectively. Lymphotactin chemotactic responses were examined by in-vitro chemotaxis assay. In-vitro activation of CTLs by DCLptn/H22 fusion was measured by detecting CD25 expression and cytokine production after autologous T cell stimulation. Cytotoxic function of activated T lymphocytes stimulated with DCLptn/H22 cells was determined by LDH cytotoxicity assay.

RESULTS

Lymphotactin gene could be efficiently transduced to DCs by adenovirus vector and showed an effective biological activity. After fusion, the hybrid DCLptn/H22 cells acquired the phenotypes of both DCLptn and H22 cells. In T cell proliferation assay, flow cytometry showed a very high CD25 expression, and cytokine release assay showed a significantly higher concentration of IFN-gamma and IL-2 in DCLptn/H22 group than in DCLptn, DCLptn+H22, DC/H22 or H22 groups. Cytotoxicity assay revealed that T cells derived from DCLptn/H22 group had much higher anti-tumor activity than those derived from DCLptn, H22, DCLptn+H22, DC/H22 groups.

CONCLUSION

Lymphotactin gene-modified dendritoma induces T-cell proliferation and strong CTL reaction against allogenic HCC cells. Immunization-engineered fusion hybrid vaccine is an attractive strategy in prevention and treatment of HCC metastases.