Department of Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
Mol Med. 2013 May 20;19(1):88-98. doi: 10.2119/molmed.2012.00306.
High mobility group box 1 (HMGB1) is a DNA-binding protein that possesses cytokinelike, proinflammatory properties when released extracellularly in the C23-C45 disulfide form. HMGB1 also plays a key role as a mediator of acute and chronic inflammation in models of sterile injury. Although HMGB1 interacts with multiple pattern recognition receptors (PRRs), many of its effects in injury models occur through an interaction with toll-like receptor 4 (TLR4). HMGB1 interacts directly with the TLR4/myeloid differentiation protein 2 (MD2) complex, although the nature of this interaction remains unclear. We demonstrate that optimal HMGB1-dependent TLR4 activation in vitro requires the coreceptor CD14. TLR4 and MD2 are recruited into CD14-containing lipid rafts of RAW264.7 macrophages after stimulation with HMGB1, and TLR4 interacts closely with the lipid raft protein GM1. Furthermore, we show that HMGB1 stimulates tumor necrosis factor (TNF)-α release in WT but not in TLR4(-/-), CD14(-/-), TIR domain-containing adapter-inducing interferon-β (TRIF)(-/-) or myeloid differentiation primary response protein 88 (MyD88)(-/-) macrophages. HMGB1 induces the release of monocyte chemotactic protein 1 (MCP-1), interferon gamma-induced protein 10 (IP-10) and macrophage inflammatory protein 1α (MIP-1α) in a TLR4- and CD14-dependent manner. Thus, efficient recognition of HMGB1 by the TLR4/MD2 complex requires CD14.
高迁移率族蛋白 B1（HMGB1）是一种 DNA 结合蛋白，当其以 C23-C45 二硫键形式释放到细胞外时，具有细胞因子样、促炎特性。HMGB1 还在无菌损伤模型中作为急性和慢性炎症的介质发挥关键作用。尽管 HMGB1 与多种模式识别受体（PRRs）相互作用，但在损伤模型中，其许多作用是通过与 Toll 样受体 4（TLR4）相互作用产生的。HMGB1 与 TLR4/髓样分化蛋白 2（MD2）复合物直接相互作用，尽管这种相互作用的性质尚不清楚。我们证明，体外最佳的 HMGB1 依赖性 TLR4 激活需要共受体 CD14。TLR4 和 MD2 在 RAW264.7 巨噬细胞中受到 HMGB1 刺激后被募集到包含 CD14 的脂筏中，并且 TLR4 与脂筏蛋白 GM1 密切相互作用。此外，我们表明 HMGB1 刺激 WT 巨噬细胞而非 TLR4(-/-)、CD14(-/-)、TIR 结构域包含衔接子诱导干扰素-β（TRIF）(-/-)或髓样分化初级反应蛋白 88（MyD88）(-/-)巨噬细胞释放肿瘤坏死因子（TNF）-α。HMGB1 以 TLR4 和 CD14 依赖的方式诱导单核细胞趋化蛋白 1（MCP-1）、干扰素γ诱导蛋白 10（IP-10）和巨噬细胞炎症蛋白 1α（MIP-1α）的释放。因此，TLR4/MD2 复合物对 HMGB1 的有效识别需要 CD14。
