Browsing by Subject "dendritic cells"
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Item Open Access Early Carcinogenesis Involves the Establishment of Immune Privilege via Intrinsic and Extrinsic Regulation of Indoleamine 2,3-dioxygenase-1: Translational Implications in Cancer Immunotherapy.(Front Immunol, 2014) Holtzhausen, Alisha; Zhao, Fei; Evans, Kathy S; Hanks, Brent AAlthough prolonged genetic pressure has been conjectured to be necessary for the eventual development of tumor immune evasion mechanisms, recent work is demonstrating that early genetic mutations are capable of moonlighting as both intrinsic and extrinsic modulators of the tumor immune microenvironment. The indoleamine 2,3-dioxygenase-1 (IDO) immunoregulatory enzyme is emerging as a key player in tumor-mediated immune tolerance. While loss of the tumor suppressor, BIN-1, and the over-expression of cyclooxygenase-2 have been implicated in intrinsic regulation of IDO, recent findings have demonstrated the loss of TβRIII and the upregulation of Wnt5a by developing cancers to play a role in the extrinsic control of IDO activity by local dendritic cell populations residing within tumor and tumor-draining lymph node tissues. Together, these genetic changes are capable of modulating paracrine signaling pathways in the early stages of carcinogenesis to establish a site of immune privilege by promoting the differentiation and activation of local regulatory T cells. Additional investigation of these immune evasion pathways promises to provide opportunities for the development of novel strategies to synergistically enhance the efficacy of the evolving class of T cell-targeted "checkpoint" inhibitors.Item Open Access Enhancing Chimeric Antigen Receptor T cell therapy in Mouse EGFRvIII Heterogeneous Glioblastoma(2023) Swan, Sheridan Leigh-CarrollChimeric antigen receptor (CAR) T cell therapy for glioblastoma remains challenging due to insufficient CAR T cell abundance and antigen-negative tumor cells evading targeting. Unfortunately, most preclinical studies evaluating CAR T cells in glioblastoma use tumors expressing a single antigen, xenografts, and/or lymphodepletion. While lymphodepletion enhances CAR T cell efficacy, it diminishes the endogenous immune system, which has the potential for tumor eradication. Here, we orthotopically delivered IL7 and/or Flt3L expressing CAR T cells in 50% EGFRvIII-positive and -negative tumors pre-conditioned with non-lymphodepleting irradiation. IL7 and IL7 Flt3L CAR T cells increased intratumoral CD8 CAR T cell populations seven days after treatment. IL7 co-expression with Flt3L increased conventional dendritic cells (cDCs) as well as the CD103+XCR1+ population known for migration and antigen cross-presentation. Treatment with IL7 or IL7 Flt3L CAR T cells improved overall survival to 67% and 50%, respectively, compared to 9% in vCAR and vFL and no survivors in PBS treated. However, there was no significant difference in survival between IL7 and IL7 Flt3L CAR T cells. We conclude that CAR T cells modified to express IL7 demonstrate therapeutic potential in glioblastoma treated with non-lymphodepleting irradiation and co-expression with Flt3L modestly improved intratumoral dendritic cell populations.
Item Open Access Incorporation of CpG Oligodeoxynucleotides into α2-Macroglobulin: Development of a Novel Vaccine Adjuvant Delivery Mechanism(2007-05-02T14:53:43Z) Anderson, Ryan BergerBacterial DNA is immunostimulatory, and the motifs responsible for this activity are unmethylated CpG dinucleotides. Following cellular uptake, CpG-containing oligodeoxynucleotides (CpG ODN) are trafficked to the endosome where they bind Toll-like receptor 9 (TLR9) to initiate a signaling cascade that culminates in the release of numerous pro-inflammatory cytokines. Because of their immunostimulatory properties, CpG ODN are being clinically evaluated as treatments and vaccine adjuvants for infectious diseases, cancer, and allergic disorders. α2-Macroglobulin (α2M) is a human plasma protein that binds and modulates the activity of a variety of cytokines, growth factors, enzymes, and antigens. Upon proteolytic activation, α2M is converted to its receptor recognized form, α2M*, and rapidly binds to and is internalized by immune competent cells expressing the α2M* endocytic receptor, LRP, and is then trafficked to the endosome. Based on these interactions, α2M seems to play an important role at sites of infection and inflammation by controlling the level of proteinase activity, modulating cytokine signals, and enhancing antigen processing for the adaptive immune response. Here, we report the first evidence that α2M* binds and forms stable complexes with nucleic acids. We have characterized the mechanisms and stoichiometry of this interaction, examined the pH and temperature stability of these complexes, and identified structural variables in the nucleic acids, namely length, base composition, and chemical modifications, that affect the nature of this interaction. We hypothesized that CpG ODN incorporation into α2M* may alter their immunostimulatory properties. Murine macrophages (MΦs) treated with α2M*-ODN complexes respond more rapidly and produce a greater cytokine response than those treated with free CpG ODN alone. Treating human PBMCs with α2M*-ODN complexes likewise demonstrated their enhanced ability to elicit immune responses. This was due to more rapid uptake and CpG ODN protection from degradation by extracellular nucleases. Co-incorporation of both protein ligands and CpG ODN into α2M* yields ternary complexes; these may permit the simultaneous delivery of both protein antigens and adjuvants to immune competent cells, potentially greatly enhancing the adaptive immune response and protective immunity. Based on the findings that incorporation into α2M* confers enhanced immunostimulatory activity of CpG ODN, this technology may be exploited to improve CpG ODN-based therapeutics by increasing efficacy, minimizing side effects, reducing dosing requirements, and reducing cost.Item Open Access Inflammatory Th1 and Th17 in the Intestine Are Each Driven by Functionally Specialized Dendritic Cells with Distinct Requirements for MyD88.(Cell Rep, 2016-10-25) Liang, Jie; Huang, Hsin-I; Benzatti, Fernanda P; Karlsson, Amelia B; Zhang, Junyi J; Youssef, Nourhan; Ma, Averil; Hale, Laura P; Hammer, Gianna ENormal dynamics between microbiota and dendritic cells (DCs) support modest numbers of T cells, yet these do not cause inflammation. The DCs that induce inflammatory T cells and the signals that drive this process remain unclear. Here, we demonstrate that small intestine DCs lacking the signaling attenuator A20 induce inflammatory T cells and that the signals perceived and antigen-presenting cell (APC) functions are unique for different DC subsets. Thus, although CD103(+)CD11b(-) DCs exclusively instruct IFNγ(+) T cells, CD103(+)CD11b(+) DCs exclusively instruct IL-17(+) T cells. Surprisingly, APC functions of both DC subsets are upregulated in a MyD88-independent fashion. In contrast, CD103(-)CD11b(+) DCs instruct both IFNγ(+) and IL-17(+) T cells, and only the IL-17-inducing APC functions require MyD88. In disease pathogenesis, both CD103(-)CD11b(+) and CD103(+)CD11b(+) DCs expand pathologic Th17 cells. Thus, in disease pathogenesis, specific DCs instruct specific inflammatory T cells.Item Open Access Poxvirus Modulation of the Immune Response(2009) Spesock, AprilOrthopoxviruses encode many genes that are not essential for viral replication, which often account for differences in pathogenesis among otherwise closely related orthopoxviruses. Although dendritic cells (DCs) are essential to the generation of an effective anti-viral immune response, the effects of different orthopoxviruses on DC function is poorly understood. The objective of these studies was to determine the effect of different orthopoxviruses on DCs. Cowpox virus (CPXV) is ideally suited to this purpose because it encodes the largest and most representative set of accessory genes among orthopoxviruses, it is endemic in mouse populations, and can infect humans.
We hypothesized that CPXV would have novel mechanisms of evading the immune response that other orthopoxviruses lack, which may exert maximal effect in the context of antigen presenting cells such as DCs, allowing for discovery of novel viral strategies of immune evasion. To test this, CPXV was used to infected mouse bone marrow-derived DCs (BMDCs), and the effect of the virus on DC survival, expression of T-cell costimulatory molecules and cytokine production was determined. The effects of vaccinia virus strain Western Reserve (VV), the prototype of the species, and modified vaccinia virus strain Ankara (MVA), a promising vaccine vector, on mouse BMDCs were also determined. Confirming the hypothesis that CPXV would have different effects on mouse BMDCs from other orthopoxviruses, BMDCs infected with CPXV survived longer in culture than those infected with MVA or VV. In addition, CPXV specifically downregulated MHC I, MHC II, CD40, and CD86, and induced production of significant levels of IL-6 and IL-10.
Because IL-10 has many suppressive effects on the immune system, inducing IL-10 may provide a selective advantage to CPXV in vivo. To examine the role of IL-10 in a CPXV infection, wild type and IL-10 deficient mice were infected intranasally with CPXV. The effect of CPXV infection on disease morbidity, viral loads, inflammation and the protective immune response was determined. As expected, IL-10 was important in controlling inflammation during CPXV infection, but there was no effect on viral replication or clearance. Surprisingly, IL-10 was important in generation of a protective memory response to CPXV, which may reflect a novel role for IL-10 in the immune response.
Item Open Access Receptor-Mediated Antigen Delivery by Α2-Macroglobulin: Effect on Cytotoxic T Lymphocyte Immunity and Implications for Vaccine Development(2009) Bowers, Edith VilletteThe receptor-recognized form of α2-macroglobulin (α2M*) targets antigens (Ag) to professional Ag-presenting cells (APCs) for rapid internalization, processing, and presentation. When employed as an Ag delivery vehicle, α2M* amplifies major histocompatibility complex (MHC) class II presentation as demonstrated by increased antibody (Ab) titers. Recent evidence, however, suggests that α2M*-encapsulation may also enhance Ag-specific cytotoxic T lymphocyte (CTL) immunity. In these studies, we demonstrate that α2M*-delivered Ag (ovalbumin, OVA) enhances the production of specific in vitro and in vivo CTL responses.
Murine splenocytes expressing a transgenic T cell receptor (TCR) specific for CTL peptide OVA257-264 (SIINFEKL) demonstrated up to 25-fold greater IFN-γ and IL-2 secretion when treated in vitro with α2M*-OVA compared to soluble OVA. The frequency of IFN-γ -producing cells was increased ~15-fold as measured by ELISPOT. Expansion of the OVA-specific CD8+ T cells, as assayed by tetramer binding and [3H]thymidine incorporation, and cell-mediated cytotoxicity, as determined by a flow cytometric assay, were also significantly enhanced by α2M*-OVA. Furthermore, CTL responses were observed at Ag doses tenfold lower than those required with OVA alone.
We also observed enhanced humoral and CTL responses by naïve mice following intradermal immunization with α2M*-OVA. These α2M*-OVA-immunized mice displayed increased protection against a subcutaneously implanted OVA-expressing tumor, as demonstrated by delayed tumor growth and prolonged animal survival. The anti-tumor response observed with α2M*-mediated Ag delivery was comparable to that of an accepted vaccine adjuvant (CpG 1826) and appeared superior to a cell-based vaccine technique.
To further understand the mechanism underlying this enhanced CTL immunity, the subsets of professional APCs capable of cross-presenting α2M*-encapsulated Ag were investigated. Although both dendritic cells (DCs) and macrophages appear to stimulate some degree of cross-priming in response to α2M*-encapsulated Ag, CD8+CD4- and CD8-CD4+ DCs appear to do so with the greatest efficiency. The implications of this finding to the ongoing debate regarding the relative contributions of APC subsets to Ag cross-presentation and the determinants of which cells cross-present with high efficiency are discussed.
These observations demonstrate that α2M*-mediated Ag delivery promotes cross-presentation resulting in enhanced Ag-specific CTL immunity. Considered in the context of previous work, these results support α2M* as an effective Ag delivery system that may be particularly useful for vaccines based on weakly immunogenic subunits or requiring dose sparing.