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RKIP contributes to IFN-γ synthesis by CD8+ T cells after serial TCR triggering in systemic inflammatory response
Kyle T Wright1, Anthony T Vella
1Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030, USA.
Abstract:
Systemic inflammatory response syndrome (SIRS) is associated with the development of severe medical complications, including progression to multiple organ dysfunction syndrome and even death. To date, only marginal improvements in terms of therapeutic options have been established for patients affected by SIRS. Raf kinase inhibitor protein (RKIP) is a regulator of MAPK and NF-κB signaling cascades, which are both critical for production of the proinflammatory cytokines responsible for SIRS initiation. By testing a T cell-dependent mouse model of SIRS that utilizes staphylococcal enterotoxin A specific for Vβ3(+) T cells, we show that RKIP is necessary for the exaggerated production of IFN-γ from SIRS splenocytes. This effect was not due to differences in T cell expansion, IL-10 production, or APC priming, but rather a cell-intrinsic defect lying downstream of the TCR in staphylococcal enterotoxin A-specific CD8(+) T cells. Importantly, mice lacking RKIP were still able to proliferate, survive, and contribute to cytokine production in response to pathogen associated molecular pattern-TLR-mediated stimuli, despite the TCR-dependent defects seen in our SIRS model. Finally, by blocking RKIP in wild-type SIRS splenocytes, the IFN-γ response by CD8(+) Vβ3(+) T cells was significantly diminished. These data suggest that RKIP may be a potential therapeutic target in SIRS by curbing effector cytokine production from CD8(+) T cells during serial TCR triggering.
Insights
Raf kinase inhibitor protein (RKIP) is crucial for excessive IFN-γ production in Systemic Inflammatory Response Syndrome (SIRS). Targeting RKIP may reduce T cell-driven inflammation in SIRS patients.
Area of Science:
- Immunology
- Molecular Biology
- Cellular Biology
Background:
- Systemic Inflammatory Response Syndrome (SIRS) can lead to severe complications and death.
- Current therapeutic options for SIRS offer limited improvements.
- Raf kinase inhibitor protein (RKIP) modulates MAPK and NF-κB pathways, key in pro-inflammatory cytokine production.
Purpose of the Study:
- To investigate the role of RKIP in the pathogenesis of SIRS.
- To determine if RKIP influences T cell-mediated cytokine production during SIRS.
- To explore RKIP as a potential therapeutic target for SIRS.
Main Methods:
- Utilized a T cell-dependent mouse model of SIRS induced by staphylococcal enterotoxin A (SEA).
- Assessed IFN-γ production in splenocytes from wild-type and RKIP-deficient mice.
- Examined T cell expansion, IL-10 production, APC priming, and responses to TLR-mediated stimuli.
- Blocked RKIP function in wild-type SIRS splenocytes.
Main Results:
- RKIP deficiency in mice led to reduced exaggerated IFN-γ production from SIRS splenocytes.
- The defect was cell-intrinsic to CD8(+) T cells, downstream of T cell receptor (TCR) signaling.
- RKIP-deficient mice maintained normal responses to pathogen-associated molecular pattern-TLR stimuli.
- Blocking RKIP in wild-type splenocytes significantly diminished IFN-γ response in CD8(+) T cells.
Conclusions:
- RKIP is essential for exaggerated IFN-γ production by CD8(+) T cells in a mouse model of SIRS.
- RKIP's role is specific to TCR-dependent activation, not general immune responses.
- RKIP represents a potential therapeutic target for modulating CD8(+) T cell effector functions in SIRS.
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