Tachado Souvenir D, Zhang Jianmin, Zhu Jinping, Patel Naimish, Cushion Melanie, Koziel Henry
Division of Pulmoary, Critical Care and Sleep Medicine, Department of Medicine, Kirstein Hall, Room E/KSB-23, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
J Leukoc Biol. 2007 Jan;81(1):205-11. doi: 10.1189/jlb.1005580. Epub 2006 Oct 4.
Interaction with the unique fungus Pneumocystis (Pc) promotes IL-8 release by human alveolar macrophages (AM), although the receptor(s) mediating IL-8 release have not been identified. TLR2 recognizes fungal components and mediates release of host defense cytokines and chemokines, although whether TLR2 mediates signaling in response to Pc is not known. In the current study, Pc induced IL-8 release by human AM, and AM pretreatment with anti-TLR2 neutralizing antibody reduced IL-8 release. However, in nonphagocytic human embryonic kidney (HEK)293 cells transfected with human TLR2 cDNA, incubation with Pc did not induce IL-8 release, whereas these same cells released IL-8 in response to the TLR2 agonist lipoteichoic acid. Targeted gene silencing of AM mannose receptors (MR; phagocytic receptors for Pc) using small interfering RNA also reduced Pc-mediated IL-8 release in human AM. However, HEK293 cells transfected with human MR cDNA alone did not release IL-8 in response to Pc. In contrast, HEK293 cells cotransfected with human TLR2 and human MR cDNA released IL-8 in response to Pc. In human AM, Pc promoted direct interaction of MR and TLR2, IL-8 release was reduced markedly upon simultaneous blocking of TLR2 and gene silencing of MR, and IL-8 release was dependent in part on transcription factor NF-kappaB and ERK1/2 and JNK MAPKs. These studies demonstrate that Pc-mediated IL-8 release by human AM requires the coexpression of MR and TLR2 and further supports the concept that combinatorial interactions of macrophage innate receptors provide specificity of host defense cell responses to infectious challenge.
与独特的真菌肺孢子菌（Pc）相互作用可促进人肺泡巨噬细胞（AM）释放白细胞介素-8（IL-8），尽管介导IL-8释放的受体尚未明确。Toll样受体2（TLR2）可识别真菌成分并介导宿主防御细胞因子和趋化因子的释放，不过TLR2是否介导对Pc的信号传导尚不清楚。在本研究中，Pc可诱导人AM释放IL-8，用抗TLR2中和抗体预处理AM可减少IL-8释放。然而，在转染了人TLR2 cDNA的非吞噬性人胚肾（HEK）293细胞中，与Pc孵育并未诱导IL-8释放，而这些相同的细胞对TLR2激动剂脂磷壁酸有反应并释放IL-8。使用小干扰RNA对AM甘露糖受体（MR；Pc的吞噬受体）进行靶向基因沉默也可减少人AM中Pc介导的IL-8释放。然而，单独转染人MR cDNA的HEK293细胞对Pc无反应而不释放IL-8。相反，共转染人TLR2和人MR cDNA的HEK293细胞对Pc有反应并释放IL-8。在人AM中，Pc促进MR与TLR2的直接相互作用，同时阻断TLR2和对MR进行基因沉默时，IL-8释放明显减少，且IL-8释放部分依赖于转录因子核因子κB以及细胞外信号调节激酶1/2（ERK1/2）和应激活化蛋白激酶（JNK）丝裂原活化蛋白激酶（MAPK）。这些研究表明，人AM中Pc介导的IL-8释放需要MR和TLR2的共表达，并进一步支持了巨噬细胞固有受体的组合相互作用为宿主防御细胞对感染性刺激的反应提供特异性这一概念。
