Mannan-binding lectin directly interacts with Toll-like receptor 4 and suppresses lipopolysaccharide-induced inflammatory cytokine secretion from THP-1 cells
Mannan-binding lectin directly interacts with Toll-like receptor 4 and suppresses lipopolysaccharide-induced inflammatory cytokine secretion from THP-1 cells
复制标题
甘露聚糖结合凝集素直接与 Toll 样受体 4 相互作用并抑制脂多糖诱导的 THP-1 细胞炎症细胞因子分泌
DOI：
10.1038/cmi.2011.1
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发表时间：
2011-05-01
影响因子：
24.1
通讯作者：
Chen, Zhengliang
中科院分区：
文献类型：
--
作者：
Wang, Mingyong;Chen, Yue;Chen, Zhengliang
甘露聚糖结合凝集素（MBL）在补体激活的凝集素途径中起关键作用，并可影响细胞因子的表达。Toll样受体4（TLR 4）广泛表达，并已被证明参与脂多糖（LPS）诱导的信号传导。我们首先试图通过使用单核细胞样细胞系THP-1来确定MBL暴露是否可以调节LPS诱导的炎性细胞因子分泌和核因子-κB（NF-κB）活性。然后，我们研究了任何观察到的调节作用的可能机制。利用ELISA和逆转录聚合酶链反应（RT-PCR）分析，我们发现，在蛋白质和mRNA水平上，MBL处理抑制LPS诱导的THP-1细胞中肿瘤坏死因子（TNF）-α和IL-12的产生。电泳迁移率变动分析和western blot分析显示MBL处理可抑制LPS诱导的THP-1细胞NF-κB DNA结合和转位。虽然MBL与THP-1细胞的结合在生理钙浓度下是明显的，但这种结合最佳地响应于超生理钙浓度而发生。这种结合可以通过用可溶形式的重组TLR 4胞外结构域或抗TLR 4单克隆抗体（HTA 125）处理而部分抑制。通过LPS处理活化THP-1细胞导致MBL结合增加。我们还观察到MBL可以以剂量依赖的方式直接与TLR 4的胞外结构域结合，并且这种相互作用可以减弱LPS与细胞表面的结合。总之，这些数据表明，MBL可能会影响细胞因子的表达，通过调节LPS-/TLR-信号通路。这些发现表明MBL可能在免疫调节和细胞因子网络中的信号通路中起重要作用。
Mannan-binding lectin (MBL) plays a key role in the lectin pathway of complement activation and can influence cytokine expression. Toll-like receptor 4 (TLR4) is expressed extensively and has been demonstrated to be involved in lipopolysaccharide (LPS)-induced signaling. We first sought to determine whether MBL exposure could modulate LPS-induced inflammatory cytokine secretion and nuclear factor-κB (NF-κB) activity by using the monocytoid cell line THP-1. We then investigated the possible mechanisms underlying any observed regulatory effect. Using ELISA and reverse transcriptase polymerase chain reaction (RT-PCR) analysis, we found that at both the protein and mRNA levels, treatment with MBL suppresses LPS-induced tumor-necrosis factor (TNF)-α and IL-12 production in THP-1 cells. An electrophoretic mobility shift assay and western blot analysis revealed that MBL treatment can inhibit LPS-induced NF-κB DNA binding and translocation in THP-1 cells. While the binding of MBL to THP-1 cells was evident at physiological calcium concentrations, this binding occurred optimally in response to supraphysiological calcium concentrations. This binding can be partly inhibited by treatment with either a soluble form of recombinant TLR4 extracellular domain or anti-TLR4 monoclonal antibody (HTA125). Activation of THP-1 cells by LPS treatment resulted in increased MBL binding. We also observed that MBL could directly bind to the extracellular domain of TLR4 in a dose-dependent manner, and this interaction could attenuate the binding of LPS to cell surfaces. Taken together, these data suggest that MBL may affect cytokine expression through modulation of LPS-/TLR-signaling pathways. These findings suggest that MBL may play an important role in both immune regulation and the signaling pathways involved in cytokine networks.