[P2-3-24] Role of caspase-11 and priming effects of a dectin-1 ligand on poly(I:C)-induced production of proinflammatory cytokines and interferon (IFN)-β
Keywords:caspase-11、Toll-like receptor、dectin-1
[Objective] In this study, we investigated the role of caspase-11 and priming effects of curdlan, a dectin-1 ligand, or zymosan, a TLR2 and dectin-1 ligand, on production of interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, tumor necrosis factor (TNF)-α, and IFN-β by mouse macrophage-like cells incubated with polyinosinic-polycytidylic acid (poly(I:C)), a ligand of TLR3 and retinoic acid-inducible gene-I (RIG-I).
[Methods] J774.1 cells, RAW-ASC cells or caspase-11 knockout RAW-ASC cells were pretreated with or without curdlan or zymosan in 96-well flat-bottomed plates for 24 h. Cells were then washed and incubated with poly(I:C) or imiquimod, a TLR7 ligand, for 24 h. Culture supernatants were analyzed by ELISA for secreted mouse IL-6, MCP-1, TNF-α, and IFN-β. Expression of RIG-I, caspase-11, interferon regulatory factor (IRF)-3, or IRF-5 was analyzed by western blotting.
[Results and Discussion] Pretreatment with curdlan augmented poly(I:C)-induced production of IL-6, MCP-1, TNF-α, and IFN-β by J774.1 cells. Treatment with curdlan or zymosan for 24 h upregulated RIG-I expression and significantly activated caspase-11 by J774.1 cells. However, curdlan did not augment imiquimod-induced production of IL-6, MCP-1, and TNF-α by J774.1 cells. In addition, IFN-β production induced by imiquimod was reduced when cells were pretreated with curdlan. Pretreatment with curdlan not only upregulated poly(I:C)-induced the translocation of IRF-3 and IRF-5 to the nuclei, but also downregulate the translocation induced by imiquimod. Activation of caspase-11 by TLR2 or TLR7 ligands (MyD88-dependent) was weaker than by ligands which have MyD88-independent pathway. These results suggest that pretreatment with dectin-1 ligand may augment poly(I:C)-induced cytokine production by upregulating RIG-I expression, and caspase-11 may upregulate cytokine production through MyD88-independent pathway.
[Methods] J774.1 cells, RAW-ASC cells or caspase-11 knockout RAW-ASC cells were pretreated with or without curdlan or zymosan in 96-well flat-bottomed plates for 24 h. Cells were then washed and incubated with poly(I:C) or imiquimod, a TLR7 ligand, for 24 h. Culture supernatants were analyzed by ELISA for secreted mouse IL-6, MCP-1, TNF-α, and IFN-β. Expression of RIG-I, caspase-11, interferon regulatory factor (IRF)-3, or IRF-5 was analyzed by western blotting.
[Results and Discussion] Pretreatment with curdlan augmented poly(I:C)-induced production of IL-6, MCP-1, TNF-α, and IFN-β by J774.1 cells. Treatment with curdlan or zymosan for 24 h upregulated RIG-I expression and significantly activated caspase-11 by J774.1 cells. However, curdlan did not augment imiquimod-induced production of IL-6, MCP-1, and TNF-α by J774.1 cells. In addition, IFN-β production induced by imiquimod was reduced when cells were pretreated with curdlan. Pretreatment with curdlan not only upregulated poly(I:C)-induced the translocation of IRF-3 and IRF-5 to the nuclei, but also downregulate the translocation induced by imiquimod. Activation of caspase-11 by TLR2 or TLR7 ligands (MyD88-dependent) was weaker than by ligands which have MyD88-independent pathway. These results suggest that pretreatment with dectin-1 ligand may augment poly(I:C)-induced cytokine production by upregulating RIG-I expression, and caspase-11 may upregulate cytokine production through MyD88-independent pathway.