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Artificial Antigen Presenting Cell aAPC Mediated Activation and Expansion of Natural Killer T Cells
Published on: December 29, 2012
Enhanced IL-15-mediated NK cell activation and proliferation by an ADAM17 function-blocking antibody involves CD16A,
Anders W Matson1, Rob Hullsiek2, Kate J Dixon3
1Graduate Program in Comparative and Molecular Biosciences, University of Minnesota, Saint Paul, Minnesota, USA.
Background:
Natural killer (NK) cells are being extensively studied as a cell therapy for cancer. These cells are activated by recognition of ligands and antigens on tumor cells. Cytokine therapies, such as IL-15, are also broadly used to stimulate endogenous and adoptively transferred NK cells in patients with cancer. These stimuli activate the membrane protease ADAM17, which cleaves various cell-surface receptors on NK cells as a negative feedback loop to limit their cytolytic function. ADAM17 inhibition can enhance IL-15-mediated NK cell proliferation in vitro and in vivo. In this study, we investigated the underlying mechanism of this process.
Methods:
Peripheral blood mononuclear cells (PBMCs) or enriched NK cells from human peripheral blood, either unlabeled or labeled with a cell proliferation dye, were cultured for up to 7 days in the presence of rhIL-15±an ADAM17 function-blocking antibody. Different fully human versions of the antibody were generated; Medi-1 (IgG1), Medi-4 (IgG4), Medi-PGLALA, Medi-F(ab')2, and TAB16 (anti-ADAM17 and anti-CD16 bispecific) to modulate CD16A binding. Flow cytometry was used to assess NK cell proliferation and phenotypic markers, immunoblotting to examine CD16A signaling, and IncuCyte-based live cell imaging to measure NK cell antitumor activity.
Results:
The ADAM17 function-blocking monoclonal antibody (mAb) Medi-1 markedly increased early NK cell activation by IL-15. By using different engineered versions of the antibody, we demonstrate involvement by CD16A, an activating Fcγ receptor and well-described ADAM17 substrate. Hence, Medi-1 when bound to ADAM17 on NK cells is engaged by CD16A and blocks its shedding, inducing and prolonging its signaling. This process did not promote evident NK cell fratricide or dysfunction. Synergistic signaling by Medi-1 and IL-15 enhanced the upregulation of CD137 on CD16A+ NK cells and augmented their proliferation in the presence of PBMC accessory cells or an anti-CD137 agonistic mAb.
Conclusions:
Our data reveal for the first time that CD16A and CD137 underpin Medi-1 enhancement of IL-15-driven NK cell activation and proliferation, respectively, with the latter requiring PBMC accessory cells. The use of Medi-1 represents a novel strategy to enhance IL-15-driven NK cell proliferation, and it may be of therapeutic importance by increasing the antitumor activity of NK cells in patients with cancer.
Insights
Inhibiting ADAM17 with the Medi-1 antibody enhances IL-15-driven natural killer (NK) cell activation and proliferation. This novel strategy boosts NK cell antitumor activity, offering therapeutic potential for cancer treatment.
Area of Science:
- Immunology
- Cell Biology
- Cancer Therapy
Background:
- Natural killer (NK) cells are crucial for cancer immunotherapy, activated by tumor cell ligands and cytokines like IL-15.
- The protease ADAM17 negatively regulates NK cell function by cleaving cell-surface receptors.
- Inhibiting ADAM17 can enhance IL-15-mediated NK cell proliferation, a mechanism requiring further investigation.
Purpose of the Study:
- To investigate the mechanism by which ADAM17 inhibition enhances IL-15-driven NK cell proliferation.
- To explore the role of CD16A and CD137 in mediating the effects of ADAM17 inhibition.
Main Methods:
- Cultured human peripheral blood mononuclear cells (PBMCs) or enriched NK cells with rhIL-15 and/or an ADAM17 function-blocking antibody (Medi-1 and variants).
- Assessed NK cell proliferation and phenotype using flow cytometry.
- Examined CD16A signaling via immunoblotting and measured NK cell antitumor activity using live cell imaging.
Main Results:
- The ADAM17 blocking antibody Medi-1 significantly enhanced early NK cell activation by IL-15.
- CD16A engagement with Medi-1 blocked ADAM17 shedding, prolonging NK cell signaling without inducing dysfunction.
- Synergistic signaling between Medi-1 and IL-15 upregulated CD137 on CD16A+ NK cells, augmenting proliferation with accessory cells.
Conclusions:
- CD16A and CD137 mediate the enhanced NK cell activation and proliferation induced by Medi-1 and IL-15.
- Medi-1 represents a novel therapeutic strategy to boost IL-15-driven NK cell proliferation.
- This approach holds potential for increasing NK cell antitumor activity in cancer patients.
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