Interferon regulatory factor 4 negatively regulates the production of proinflammatory cytokines by macrophages in response to LPS

Authors:
Honma K, Udono H, Kohno T, Yamamoto K, Ogawa A, Takemori T, Kumatori A, Suzuki S, Matsuyama T and Yui K
In:
Source: Proc Natl Acad Sci USA
Publication Date: (2005)
Issue: 102(44): 16001-16006
Research Area:
Immunotherapy / Hematology
Cells used in publication:
RAW 264.7
Species: mouse
Tissue Origin: blood
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
A member of the IFN regulatory factor (IRF) family of transcription factors, IRF-4 is expressed in lymphocytes and macrophage/dendritic cells. Studies using IRF-4-deficient mice have revealed the critical roles of IRF-4 in lymphocyte responses. However, the role of IRF-4 in innate immune responses is not clearly understood. Here, we demonstrate that IRF-4 negatively regulates the production of proinflammatory cytokines by macrophages in response to Toll-like receptor (TLR) stimulation. Mice lacking IRF-4 are sensitive to LPS-induced shock, and their macrophages produce high levels of proinflammatory cytokines, including TNF-alpha and IL-6, in response to TLR ligands. The inhibitory role of IRF-4 in response to TLR stimulation was confirmed by the down-regulation of IRF-4 expression in normal macrophages by using the small interfering RNA technique and by the overexpression of IRF-4 in macrophage line RAW264.7. Activation of the important signaling pathways for cytokine production, NF-kappaB and JNK (c-Jun N-terminal kinase), was enhanced after LPS stimulation in IRF-4(-/-) macrophages. These results imply that IRF-4 negatively regulates TLR signaling and is inhibitory to the production of proinflammatory cytokines in response to TLR stimulation.