Canine-DCs using different serum-free methods as an approach to provide an animal-model for immunotherapeutic strategies

Potential of immunotherapies in the mediation of antileukemic responses for patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) - With a focus on Dendritic cells of leukemic origin (DCleu)

New (non-immunotherapeutic) treatment-strategies for AML/MDS-patients are under development. Dendritic cells (DCs) and 'leukemia-derived DC' (DC_leu) connect the innate and the adaptive immunesystem and (re-)activate it, in their capacity as professional antigen-presenting cells (APCs). They can be generated ex vivo from peripheral blood mononuclear cells (PBMNCs) or whole blood (WB), containing the -physiological-cellular/soluble microenvironment of individual patients using various DC/DC_leu-generating methods or (for WB) minimalized 'Kits', containing granulocyte-macrophage-colony-stimulating-factor (GM-CSF) and a second response-modifier. Proof for DC/DC_leu-mediated activation of the immune-system after T-cell-enriched mixed lymphocyte culture (MLC) is done by flowcytometry, demonstrating increased fractions of certain activated, leukemia-specific or antileukemic cell-subsets of the innate and the adaptive immune-system. Generation of DC/DC_leu is possible independent of patients' age, MHC-, mutation- or transplantation-status. In vivo-treatment of AML-/MDS-patients with blast-modulating, DC/DC_leu- inducing 'Kits' could contribute to create migratory DCs, as well as antileukemically reactivated and memory-mediating immune-cells, which patrol tissue and blood and could contribute to stabilizing disease or remissions.

In vitro evaluations on canine monocyte-derived dendritic cells of a nanoparticles delivery system for vaccine antigen against Echinococcus granulosus

Since dogs play a central role in the contamination of humans and livestock with Echinococcus granulosus, the development of an effective vaccine for dogs is essential to control the disease caused by this parasite. For this purpose, a formulation based on biodegradable polymeric nanoparticles (NPs) as delivery system of recombinant Echinococcus granulosus antigen (tropomyosin EgTrp) adjuved with monophosphoryl lipid A (MPLA) has been developed. The obtained nanoparticles had a size of approximately 200 nm in diameter into which the antigen was correctly preserved and encapsulated. The efficiency of this system to deliver the antigen was evaluated in vitro on canine monocyte-derived dendritic cells (cMoDCs) generated from peripheral blood monocytes. After 48 h of contact between the formulations and cMoDCs, we observed no toxic effect on the cells but a strong internalization of the NPs, probably through different pathways depending on the presence or not of MPLA. An evaluation of cMoDCs activation by flow cytometry showed a stronger expression of CD80, CD86, CD40 and MHCII by cells treated with any of the tested formulations or with LPS (positive control) in comparison to cells treated with PBS (negative control). A higher activation was observed for cells challenged with EgTrp-NPs-MPLA compared to EgTrp alone. Formulations with MPLA, even at low ratio of MPLA, give better results than formulations without MPLA, proving the importance of the adjuvant in the nanoparticles structure. Moreover, autologous T CD4+ cell proliferation observed in presence of cMoDCs challenged with EgTrp-NPs-MPLA was higher than those observed after challenged with EgTrp alone (p<0.05). These first results suggest that our formulation could be used as an antigen delivery system to targeting canine dendritic cells in the course of Echinococcus granulosus vaccine development.

Autologous canine immunotherapy: short-time generated dendritic cells loaded with canine transmissible venereal tumor-whole lysate

OBJECTIVE

The aim of the present study was to evaluate the therapeutic potential of autologous DCs loaded with whole tumor cell lysate of CTVT generated under a simplified and rapid procedure in vitro production process, in a vulvar submucosal model of CTVT in dogs.

MATERIALS AND METHODS

We generated a model of intravulvar CTVT in dogs. A CTVT lysate antigen was prepared according to the method of 1-butanol and after administered with complete Freund's adjuvant via subcutaneous in female healthy dogs and challenge with CTVT cells to corroborate the immunogenicity. Short-time generated dendritic cell pulsed with CTVT whole-lysate was performed, and analyzed by FITC-dextran uptake assay and characterized using anti-canine monoclonal antibodies CD14, CD80, CD83, and DLAII by flow cytometry. Dendritic cell therapy was administered in a frequency of three times every 2 weeks when the CTVT had 4 months of growth and 89 ± 5 cm diameter. The CD3⁺, CD4⁺ and CD8⁺ lymphocytes were determined by flow cytometry, and IFN-γ by ELISA assay.

RESULTS AND DISCUSSION

The administration of CTVT whole-lysate resulted in tumor prevention. The short-time generated dendritic cell pulsed with CTVT whole-lysate administration resulted in an efficient reduction and elimination of CTVT, probably due to the increase in lymphocyte populations (CD3⁺, CD4⁺, and CD8⁺), IFN-γ production and tumor infiltrating lymphocytes.

CONCLUSION

In conclusion, this study demonstrates the efficacy of immunotherapy based in short-time generated dendritic cell pulsed with CTVT whole-lysate for the treatment of CTVT, and offer veterinary oncologists new alternative therapies to treat this and another malignancy.

CD4(+)and CD8(+)T-cell reactions against leukemia-associated- or minor-histocompatibility-antigens in AML-patients after allogeneic SCT

T-cells play an important role in the remission-maintenance in AML-patients (pts) after SCT, however the role of LAA- (WT1, PR1, PRAME) or minor-histocompatibility (mHag, HA1) antigen-specific CD4(+) and CD8(+)T-cells is not defined. A LAA/HA1-peptide/protein stimulation, cloning and monitoring strategy for specific CD8(+)/CD4(+)T-cells in AML-pts after SCT is given. Our results show that (1) LAA-peptide-specific CD8+T-cells are detectable in every AML-pt after SCT. CD8(+)T-cells, recognizing two different antigens detectable in 5 of 7 cases correlate with long-lasting remissions. Clonal TCR-Vβ-restriction exemplarily proven by spectratyping in PRAME-specific CD8(+)T-cells; high PRAME-peptide-reactivity was CD4(+)-associated, as shown by IFN-γ-release. (2) Two types of antigen-presenting cells (APCs) were tested for presentation of LAA/HA1-proteins to CD4(+)T-cells: miniEBV-transduced lymphoblastoid cells (B-cell-source) and CD4-depleted MNC (source for B-cell/monocyte/DC). We provide a refined cloning-system for proliferating, CD40L(+)CD4(+)T-cells after LAA/HA1-stimulation. CD4(+)T-cells produced cytokines (GM-CSF, IFN-γ) upon exposure to LAA/HA1-stimulation until after at least 7 restimulations and demonstrated cytotoxic activity against naive blasts, but not fibroblasts. Antileukemic activity of unstimulated, stimulated or cloned CD4(+)T-cells correlated with defined T-cell-subtypes and the clinical course of the disease. In conclusion we provide immunological tools to enrich and monitor LAA/HA1-CD4(+)- and CD8(+)T-cells in AML-pts after SCT and generate data with relevant prognostic value. We were able to demonstrate the presence of LAA-peptide-specific CD8(+)T-cell clones in AML-pts after SCT. In addition, we were also able to enrich specific antileukemic reactive CD4(+)T-cells without GvH-reactivity upon repeated LAA/HA1-protein stimulation and limiting dilution cloning.

Minor histocompatibility antigen UTY as target for graft-versus-leukemia and graft-versus-haematopoiesis in the canine model

Male patients with female-stem-cell donors have better prognosis compared to female-to-male combinations due to Y-encoded minor histocompatibility antigens recognized by female-alloimmune-effector lymphocytes in the context of a graft-versus-leukemia (GvL) effect. We provide data in a dog-model that the minor histocompatibility antigen UTY might be a promising target to further improve GvL-immune reactions after allogeneic-stem-cell transplantations. Female-canine-UTY-specific T cells (CTLs) were stimulated in vitro using autologous-DCs loaded with three HLA-A2-restricted-UTY-derived peptides (3-fold-expansion), and specific T cell responses were determined in 3/6 female dogs. CTLs specifically recognized/lysed autologous-female-peptide-loaded DCs, but not naïve-autologous-female DCs and monocytes. They mainly recognized bone-marrow (BM) and to a lower extent DCs, monocytes, PBMCs and B-cells from DLA-identical-male littermates and peptide-loaded T2-cells in an MHC-I-restricted manner. A UTY-/male-specific reactivity was also obtained in vivo after stimulation of a female dog with DLA-identical-male PBMCs. In summary, we demonstrated natural UTY processing and presentation in dogs. We showed that female-dog CTLs were specifically stimulated by HLA-A2-restricted-UTY peptides, thereby enabling recognition of DLA-identical-male cells, mainly BM cells. These observations suggest UTY as a promising candidate-antigen to improve GvL-reactions in the course of immunotherapy.

The MTAP-CDKN2A locus confers susceptibility to a naturally occurring canine cancer

BACKGROUND

Advantages offered by canine population substructure, combined with clinical presentations similar to human disorders, makes the dog an attractive system for studies of cancer genetics. Cancers that have been difficult to study in human families or populations are of particular interest. Histiocytic sarcoma is a rare and poorly understood neoplasm in humans that occurs in 15% to 25% of Bernese Mountain Dogs (BMD).

METHODS

Genomic DNA was collected from affected and unaffected BMD in North America and Europe. Both independent and combined genome-wide association studies (GWAS) were used to identify cancer-associated loci. Fine mapping and sequencing narrowed the primary locus to a single gene region.

RESULTS

Both populations shared the same primary locus, which features a single haplotype spanning MTAP and part of CDKN2A and is present in 96% of affected BMD. The haplotype is within the region homologous to human chromosome 9p21, which has been implicated in several types of cancer.

CONCLUSIONS

We present the first GWAS for histiocytic sarcoma in any species. The data identify an associated haplotype in the highly cited tumor suppressor locus near CDKN2A. These data show the power of studying distinctive malignancies in highly predisposed dog breeds.

IMPACT

Here, we establish a naturally occurring model of cancer susceptibility due to CDKN2 dysregulation, thus providing insight about this cancer-associated, complex, and poorly understood genomic region.