Lipopolysaccharide activates NF-κB by TLR4-Bcl10-dependent and independent pathways in colonic epithelial cells
Lipopolysaccharide activates NF-κB by TLR4-Bcl10-dependent and independent pathways in colonic epithelial cells
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DOI：
10.1152/ajpgi.90434.2008
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发表时间：
2008-10-01
影响因子：
4.5
通讯作者：
Tobacman, Joanne K.
中科院分区：
文献类型：
--
作者：
Bhattacharyya, Sumit;Dudeja, Pradeep K.;Tobacman, Joanne K.
在结肠上皮中，脂多糖（LPS）激活NF-κ B和IL-8的途径之一是通过Toll样受体（TLR）4、MyD 88、IRAK 1/4和B细胞CLL/淋巴瘤10（Bcl 10）。然而，这种先天免疫途径仅占NF-κ B激活的50%，因此需要其他机制来解释LPS诱导的效应。在这份报告中，我们确定了第二个途径的LPS诱导的刺激，介导的活性氧（ROS），在人类结肠上皮组织细胞的组织培养和离体小鼠结肠组织。通过ELISA测量IL-8、KC、Bcl 10、磷酸化I κ B α、核NF-κ B和磷酸化Hsp 27。TLR 4-Bcl 10通路被Bcl 10 siRNA抑制，并且在使用来自TLR 4缺陷小鼠的结肠组织的研究中。自由基清除剂Tempol或蛋白磷酸酶2A（PP 2A）对Hsp 27去磷酸化的抑制剂冈田酸可抑制ROS途径。ROS途径不受TLR 4缺陷组织或Bcl 10沉默的影响。暴露于自由基清除剂Tempol和TLR 4或Bcl 10抑制的组合需要完全抑制LPS诱导的激活。ROS途径与Hsp 27的去磷酸化有关。LPS似乎通过Bcl 10与Nemo（IKK γ）的相互作用激活I κ B α-激酶（IKK）信号体的调节组分，并通过Hsp 27与IKK β的相互作用激活催化组分。由于LPS暴露与感染性休克和全身炎症反应综合征相关，因此区分这两种LPS活化途径可能有助于预防和治疗的新方法。
In colonic epithelium, one of the pathways of lipopolysaccharide (LPS) activation of NF-kappa B and IL-8 is via Toll-like receptor (TLR) 4, MyD88, IRAK1/4, and B-cell CLL/lymphoma 10 (Bcl10). However, this innate immune pathway accounts for only similar to 50% of the NF-kappa B activation, so additional mechanisms to explain the LPS-induced effects are required. In this report, we identify a second pathway of LPS-induced stimulation, mediated by reactive oxygen species (ROS), in human colonic epithelial tissue cells in tissue culture and in ex vivo mouse colonic tissue. Measurements of IL-8, KC, Bcl10, phospho-I kappa B alpha, nuclear NF-kappa B, and phosphorylated Hsp27 were performed by ELISA. The TLR4-Bcl10 pathway was inhibited by Bcl10 siRNA and in studies with colonic tissue from the TLR4-deficient mouse. The ROS pathway was inhibited by Tempol, a free radical scavenger, or by okadaic acid, an inhibitor of Hsp27 dephosphorylation by protein phosphatase 2A (PP2A). The ROS pathway was unaffected in the TLR4-deficient tissue or by silencing of Bcl10. The combination of exposure to the free radical scavenger Tempol and of TLR4 or Bcl10 suppression was required to completely inhibit the LPS-induced activation. The ROS pathway was associated with dephosphorylation of Hsp27. LPS appears to activate both the regulatory component of the I kappa B alpha-kinase (IKK) signalosome through Bcl10 interaction with Nemo (IKK gamma) and the catalytic component through Hsp27 interaction with IKK beta. Since LPS exposure is associated with septic shock and the systemic inflammatory response syndrome, distinguishing between these two pathways of LPS activation may facilitate new approaches to prevention and treatment.