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RAGE is the major receptor for the proinflammatory activity of HMGB1 in rodent macrophages
R Kokkola1, A Andersson, G Mullins
1Department of Medicine, Rheumatology Unit, Karolinska Institutet, Stockholm, Sweden.
Abstract:
Abstract High-mobility group box chromosomal protein 1 (HMGB1) is a protein with both intranuclear functions and extracellular cytokine-like effects. In this report, we study possible candidate receptors for HMGB1 on macrophages (Mphi) and define pathways activated by HMGB1 binding. Bone marrow Mphi were prepared from Dark Agouti (DA) rats and stimulated in vitro with HMGB1. The kinetics of tumour necrosis factor (TNF) production, NO production, activation of p38 mitogen-activated protein kinase (MAPK), p44/42 MAPK- and SAPK/JNK-signalling pathways, nuclear translocation of nuclear factor kappa B (NF-kappaB) and HMGB1-induced upregulation of major histocompatibility complex (MHC) class II and CD86 were analysed. Mphi from interleukin (IL)-1 receptor type I-/-, Toll-like receptor 2 (TLR2-/-) and RAGE-/- mice were used to investigate the role of these receptors in HMGB1 signalling. HMGB1 induced TNF and NO production by Mphi, phosphorylation of all investigated MAP kinase pathways and NF-kappaB translocation, and expression of MHC class II was increased. Mphi from RAGE-/- mice produced significantly lower amounts of TNF, IL-1beta and IL-6, while IL-1RI-/- and TLR2-/- Mphi produced cytokine levels comparable with wildtype controls in response to HMGB1 stimulation. We conclude that HMGB1 has the potential to induce a proinflammatory phenotype in Mphi, with RAGE as the major activation-inducing receptor.
Insights
High-mobility group box protein 1 (HMGB1) triggers inflammation in macrophages. The receptor for advanced glycation end products (RAGE) is identified as the primary receptor mediating HMGB1
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- High-mobility group box 1 (HMGB1) protein exhibits both intracellular and extracellular functions, acting as a cytokine.
- HMGB1's role in activating immune cells like macrophages (Mphi) is under investigation.
- Understanding HMGB1's receptor interactions is crucial for deciphering inflammatory pathways.
Purpose of the Study:
- To identify candidate receptors for HMGB1 on macrophages.
- To define signaling pathways activated by HMGB1 binding to macrophages.
- To elucidate the role of specific receptors in HMGB1-mediated macrophage activation.
Main Methods:
- Bone marrow-derived macrophages (Mphi) from Dark Agouti rats were stimulated with HMGB1 in vitro.
- Kinetics of tumor necrosis factor (TNF), nitric oxide (NO) production, and MAPK pathway activation were analyzed.
- HMGB1-induced signaling was assessed using macrophages deficient in IL-1 receptor type I (IL-1RI-/-), Toll-like receptor 2 (TLR2-/-), and receptor for advanced glycation end products (RAGE-/-).
Main Results:
- HMGB1 induced TNF and NO production, MAPK pathway phosphorylation, NF-kappaB translocation, and MHC class II expression in Mphi.
- Macrophages from RAGE-/- mice showed significantly reduced TNF, IL-1beta, and IL-6 production compared to wild-type.
- Macrophages from IL-1RI-/- and TLR2-/- mice produced cytokine levels comparable to wild-type controls when stimulated with HMGB1.
Conclusions:
- HMGB1 can induce a proinflammatory phenotype in macrophages.
- The receptor for advanced glycation end products (RAGE) is the major receptor mediating HMGB1-induced macrophage activation.
- HMGB1 signaling pathways involve RAGE, contributing to inflammatory responses.
