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CARD9 CONTROLS DECTIN-1-INDUCED T-CELL CYTOTOXICITY AND TUMOR GROWTH IN MICE
Author(s): ,
Tobias Haas
Affiliations:
Klinik und Poliklinik für Innere Medizin III,Klinikum rechts der Isar, TU München,München,Germany
,
Simon Heidegger
Affiliations:
Klinik und Poliklinik für Innere Medizin III,Klinikum rechts der Isar, TU München,München,Germany
,
Hendrik Poeck
Affiliations:
Klinik und Poliklinik für Innere Medizin III,Klinikum rechts der Isar, TU München,München,Germany
Jürgen Ruland
Affiliations:
Institut für Klinische Chemie und Pathobiochemie,Klinikum rechts der Isar, TU München,München,Germany
(Abstract release date: 05/18/17) EHA Library. Haas T. 06/25/17; 182105; S818
Dr. Tobias Haas
Dr. Tobias Haas
Contributions
Abstract

Abstract: S818

Type: Oral Presentation

Presentation during EHA22: On Sunday, June 25, 2017 from 09:00 - 09:15

Location: Room N111

Background
Activation of the C-type lectin receptor Dectin-1 by beta-glucans triggers multiple signals within dendritic cells (DCs) that result in activation of innate immunity. While these mechanisms can potently prime CD8+ cytotoxic T cell (CTL) responses without additional adjuvants, the Dectin‑1 effector pathways that control CTL induction remain unclear. 

Aims
Aims of this study were:

To define details of the intracellular signalling pathway responsible for cross-priming of a CTL response after activation of the C-type lectin receptor Dectin-1. 
To analyze whether identified signalling molecules were indispensable for antitumor immunity.
To analyze whether NK cells played a role in antitumor immunity after Dectin-1-mediated CTL induction. 
 
 

Methods
We used in vitro coculture between DCs (wildtype vs gene deficient) and CD8 T cells to define signalling components of Dectin-1 induced CTL cross-priming.

We used WT and gene-deficient mice to define the signalling pathway of Dectin-1 induced CTL crosspriming in vivo and to test the role of this pathway for antitumor immunity by challenging mice with B16-Ova tumor cells intravenously, with or without depletion of CD8 T cells or NK cells, respectively.

Results
Here we demonstrate that Dectin‑1-induced CTL cross-priming in mice does not require inflammasome activation but strictly depends on the adapter protein Card9 in vitro. In vivo, Dectin-1-mediated Card9 activation after vaccination drives both expansion and activation of antigen-specific CTLs, resulting in long-lasting CTL responses which are sufficient to protect mice from tumor challenge. This Dectin-1-induced antitumor immune response was independent of natural killer (NK) cell function and completely abrogated in Card9-deficient mice. Thus, our results demonstrate that Dectin-1-triggered Card9 signaling but not inflammasome activation can potently cross-prime antigen specific CTLs, suggesting that this pathway would be a candidate for immunotherapy and vaccine development.

Conclusion
We identify Card9 as central regulator of Dectin-1-induced cross-priming of cytotoxic T cells (CTLs) in mice. These antigen specific CTLs mediate potent antitumor immunity independent of inflammasome activity and NK cells. This pathway is a candidate for immunotherapy and vaccine development.

Session topic: 24. Gene therapy, cellular immunotherapy and vaccination

Keyword(s): Tumor immunity, T cell activation, Signaling molecules, Cytotoxic T cell

Abstract: S818

Type: Oral Presentation

Presentation during EHA22: On Sunday, June 25, 2017 from 09:00 - 09:15

Location: Room N111

Background
Activation of the C-type lectin receptor Dectin-1 by beta-glucans triggers multiple signals within dendritic cells (DCs) that result in activation of innate immunity. While these mechanisms can potently prime CD8+ cytotoxic T cell (CTL) responses without additional adjuvants, the Dectin‑1 effector pathways that control CTL induction remain unclear. 

Aims
Aims of this study were:

To define details of the intracellular signalling pathway responsible for cross-priming of a CTL response after activation of the C-type lectin receptor Dectin-1. 
To analyze whether identified signalling molecules were indispensable for antitumor immunity.
To analyze whether NK cells played a role in antitumor immunity after Dectin-1-mediated CTL induction. 
 
 

Methods
We used in vitro coculture between DCs (wildtype vs gene deficient) and CD8 T cells to define signalling components of Dectin-1 induced CTL cross-priming.

We used WT and gene-deficient mice to define the signalling pathway of Dectin-1 induced CTL crosspriming in vivo and to test the role of this pathway for antitumor immunity by challenging mice with B16-Ova tumor cells intravenously, with or without depletion of CD8 T cells or NK cells, respectively.

Results
Here we demonstrate that Dectin‑1-induced CTL cross-priming in mice does not require inflammasome activation but strictly depends on the adapter protein Card9 in vitro. In vivo, Dectin-1-mediated Card9 activation after vaccination drives both expansion and activation of antigen-specific CTLs, resulting in long-lasting CTL responses which are sufficient to protect mice from tumor challenge. This Dectin-1-induced antitumor immune response was independent of natural killer (NK) cell function and completely abrogated in Card9-deficient mice. Thus, our results demonstrate that Dectin-1-triggered Card9 signaling but not inflammasome activation can potently cross-prime antigen specific CTLs, suggesting that this pathway would be a candidate for immunotherapy and vaccine development.

Conclusion
We identify Card9 as central regulator of Dectin-1-induced cross-priming of cytotoxic T cells (CTLs) in mice. These antigen specific CTLs mediate potent antitumor immunity independent of inflammasome activity and NK cells. This pathway is a candidate for immunotherapy and vaccine development.

Session topic: 24. Gene therapy, cellular immunotherapy and vaccination

Keyword(s): Tumor immunity, T cell activation, Signaling molecules, Cytotoxic T cell

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