ABSTRACT
BACKGROUND: Dendritic cells (DCs) are promising mediators of anti-tumor immune responses due to their potent antigen-presentation capacity. Unfortunately, cancer cells can often disarm differentiated DCs by rendering them incapable of maturation or by promoting their apoptosis. DC vaccine regimens attempt to generate functional DCs and preload them with Tumor-Associated Antigens (TAAs) to target various malignancies. Despite these efforts, the efficacy of DC vaccines in clinical trials is still rather disappointing to date. In addition to undergoing cancer-induced apoptosis, it is well established that DCs are intrinsically short-lived cell types. It is likely that a significant portion of infused DCs undergo apoptosis prior to locating and activating naïve TAA-reactive T cells. METHODS: In our current study, we constructed and investigated novel bicistronic lentivectors (LVs) encoding the cDNA for the xeno-TAA, rat HER-2/neu (rHER-2), along with five candidate mouse DC survival factors (c-FLIPS, c-FLIPL, Bcl-XL, M11L, and AKT-1) that operate in both the extrinsic and intrinsic cycles of apoptosis. The murine DC cell line, DC2.4 was transduced separately with each novel LV construct. Infected cells were enriched via flow cytometric methods based on rHER-2 expression. Transduced DC2.4 cell lines were then exposed to Fetal Calf Serum (FCS) withdrawal and to specific pharmacological apoptosis-inducing agents. DC2.4 cell death was assayed based on Annexin V and PI double-positive staining via flow cytometry. The phenotype and function of transduced DC2.4 cells and primary bone marrow-derived DCs were then assessed via expression and secretion of DC markers and cytokines, respectively. RESULTS: DC2.4 cells transduced with LVs encoding cDNAs for c-FLIPS, c-FLIPL, Bcl-XL, and M11L were protected from apoptosis when exposed to low FCS-containing culture media. When treated with an anti-CD95 antibody, only DC2.4 cells transduced with LVs encoding c-FLIPS and c-FLIPL were protected from apoptosis. In contrast, only DC2.4 cells transduced with LVs encoding Bcl-XL and M11L were protected from effects of staurosporine (STS) treatment. Also, LV-modified DCs maintained their original phenotype and function. CONCLUSIONS: We present evidence that by employing novel recombinant bicistronic LVs we can simultaneously load DCs with a relevant TAA and block apoptosis; thereby confirming the usage of such LVs in the modulation of DC lifespan and function.
Subject(s)
Antigens, Neoplasm/immunology , Apoptosis , Dendritic Cells/immunology , Dendritic Cells/physiology , Genetic Engineering/methods , Genetic Vectors , Lentivirus/genetics , Animals , Antigens, Neoplasm/genetics , Cell Survival , Dendritic Cells/virology , Flow Cytometry , Mice , Mice, Inbred C57BL , Transduction, GeneticABSTRACT
Farber disease (FD) is a severe inherited disorder of lipid metabolism characterized by deficient lysosomal acid ceramidase (ACDase) activity, resulting in ceramide accumulation. Ceramide and metabolites have roles in cell apoptosis and proliferation. We introduced a single-nucleotide mutation identified in human FD patients into the murine Asah1 gene to generate the first model of systemic ACDase deficiency. Homozygous Asah1(P361R/P361R) animals showed ACDase defects, accumulated ceramide, demonstrated FD manifestations and died within 7-13 weeks. Mechanistically, MCP-1 levels were increased and tissues were replete with lipid-laden macrophages. Treatment of neonates with a single injection of human ACDase-encoding lentivector diminished the severity of the disease as highlighted by enhanced growth, decreased ceramide, lessened cellular infiltrations and increased lifespans. This model of ACDase deficiency offers insights into the pathophysiology of FD and the roles of ACDase, ceramide and related sphingolipids in cell signaling and growth, as well as facilitates the development of therapy.
Subject(s)
Ceramides/metabolism , Farber Lipogranulomatosis/pathology , Acid Ceramidase/genetics , Acid Ceramidase/metabolism , Animals , Cells, Cultured , Chemokine CCL2/metabolism , Disease Models, Animal , Embryonic Stem Cells/cytology , Embryonic Stem Cells/metabolism , Farber Lipogranulomatosis/genetics , Farber Lipogranulomatosis/metabolism , Female , Gene Knock-In Techniques , Genetic Vectors/genetics , Genetic Vectors/metabolism , Homozygote , Humans , Lentivirus/genetics , Macrophages/immunology , Macrophages/physiology , Mice , Mutation , PhenotypeABSTRACT
Fabry disease is a lysosomal storage disorder caused by a deficiency of α-galactosidase A (α-gal A) activity that results in progressive globotriaosylceramide (Gb(3)) deposition. We created a fully congenic nonobese diabetic (NOD)/severe combined immunodeficiency (SCID)/Fabry murine line to facilitate the in vivo assessment of human cell-directed therapies for Fabry disease. This pure line was generated after 11 generations of backcrosses and was found, as expected, to have a reduced immune compartment and background α-gal A activity. Next, we transplanted normal human CD34(+) cells transduced with a control (lentiviral vector-enhanced green fluorescent protein (LV-eGFP)) or a therapeutic bicistronic LV (LV-α-gal A/internal ribosome entry site (IRES)/hCD25). While both experimental groups showed similar engraftment levels, only the therapeutic group displayed a significant increase in plasma α-gal A activity. Gb(3) quantification at 12 weeks revealed metabolic correction in the spleen, lung, and liver for both groups. Importantly, only in the therapeutically-transduced cohort was a significant Gb(3) reduction found in the heart and kidney, key target organs for the amelioration of Fabry disease in humans.
