Differential use of CARD9 by dectin-1 in macrophages and dendritic cells

HS Goodridge, T Shimada, AJ Wolf… - The Journal of …, 2009 - journals.aai.org
HS Goodridge, T Shimada, AJ Wolf, YMS Hsu, CA Becker, X Lin, DM Underhill
The Journal of Immunology, 2009journals.aai.org
The pattern recognition receptors TLR2 and Dectin-1 play key roles in coordinating the
responses of macrophages and dendritic cells (DC) to fungi. Induction of proinflammatory
cytokines is instructed by signals from both TLR2 and Dectin-1. A recent report identified a
role for CARD9 in innate anti-fungal responses, demonstrating CARD9-Bcl10-mediated
activation of NF-κB and proinflammatory cytokine induction in murine bone marrow-derived
DC stimulated via Dectin-1. We now report that Dectin-1-CARD9 signals fail to activate NF …
Abstract
The pattern recognition receptors TLR2 and Dectin-1 play key roles in coordinating the responses of macrophages and dendritic cells (DC) to fungi. Induction of proinflammatory cytokines is instructed by signals from both TLR2 and Dectin-1. A recent report identified a role for CARD9 in innate anti-fungal responses, demonstrating CARD9-Bcl10-mediated activation of NF-κB and proinflammatory cytokine induction in murine bone marrow-derived DC stimulated via Dectin-1. We now report that Dectin-1-CARD9 signals fail to activate NF-κB and drive TNF-α induction in murine bone marrow-derived macrophages. However, priming of bone marrow-derived macrophages with GM-CSF or IFN-γ permits Dectin-1-CARD9-mediated TNF-α induction. Analysis of other macrophage/DC populations revealed further variation in the ability of Dectin-1-CARD9 signaling to drive TNF-α production. Resident peritoneal cells and alveolar macrophages produce TNF-α upon Dectin-1 ligation, while thioglycollate-elicited peritoneal macrophages and Flt3L-derived DC do not. We present data demonstrating that CARD9 is recruited to phagosomes via its CARD domain where it enhances TLR-induced cytokine production even in cells in which Dectin-1 is insufficient to drive cytokine production. In such cells, Dectin-1, CARD9, and Bcl10 levels are not limiting, and data indicate that these cells express additional factors that restrict Dectin-1-CARD9 signaling for TNF-α induction.
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