Role of the scavenger receptor MARCO in alveolar macrophage binding of unopsonized environmental particles.
Role of the scavenger receptor MARCO in alveolar macrophage binding of unopsonized environmental particles.
复制标题
DOI：
10.1084/jem.189.9.1497
复制
发表时间：
1999-05-03
影响因子：
15.3
通讯作者：
Kobzik, L
中科院分区：
文献类型：
--
作者：
Palecanda, A;Paulauskis, J;Al-Mutairi, E;Imrich, A;Qin, G;Suzuki, H;Kodama, T;Tryggvason, K;Koziel, H;Kobzik, L
肺泡巨噬细胞（AM）通过清道夫型受体（SR）贪婪地结合和摄取未经调理的环境颗粒和细菌。与SR+/+小鼠相比，来自主要巨噬细胞SR（AI型和AII型; SR-/-）基因缺失小鼠的AM的颗粒结合没有减少，这表明其他SR也参与其中。为了鉴定这些受体，我们产生了一种单克隆抗体（mAb）PAL-1，其抑制仓鼠AM与未调理颗粒（TiO 2、Fe 2 O 3和乳胶珠;通过流式细胞术测量，抑制率分别为66 ± 5、77 ± 2和85 ± 2%）的结合。该抗体识别AM表面上的一种约70 kD的蛋白质（免疫沉淀），该蛋白质由AM和其他巨噬细胞原位表达。通过COS细胞表达分离的编码mAb PAL-1反应蛋白的cDNA克隆被发现分别与小鼠和人清道夫受体MARCO mRNA具有84和77%的同源性。用MARCO cDNA转染COS细胞赋予mAb可识别的TiO 2结合。EMAMARCO还介导未调理细菌的AM结合（mAb PAL-1对大肠杆菌和金黄色葡萄球菌结合的67 ± 5%和47 ± 4%抑制）。抗人MARCO的多克隆抗体在正常支气管肺泡灌洗（BAL）细胞（>90% AM）裂解物的蛋白质印迹上鉴定出预期的70 kD条带，并在BAL细胞离心制备物和肺组织标本中显示出人AM的强免疫标记。在正常小鼠AM中，抗MARCO mAb ED 31也显示免疫反应性并抑制未调理颗粒的结合（例如，TiO_2含量为40%左右。结合未经调理的环境粉尘和病原体的新功能表明MARCO在肺部对吸入颗粒物的反应中发挥重要作用。
Alveolar macrophages (AMs) avidly bind and ingest unopsonized environmental particles and bacteria through scavenger-type receptors (SRs). AMs from mice with a genetic deletion of the major macrophage SR (types AI and AII; SR−/−) showed no decrease in particle binding compared with SR+/+ mice, suggesting that other SRs are involved. To identify these receptors, we generated a monoclonal antibody (mAb), PAL-1, that inhibits hamster AM binding of unopsonized particles (TiO2, Fe2O3, and latex beads; 66 ± 5, 77 ± 2, and 85 ± 2% inhibition, respectively, measured by flow cytometry). This antibody identifies a protein of ∼70 kD on the AM surface (immunoprecipitation) that is expressed by AMs and other macrophages in situ. A cDNA clone encoding the mAb PAL-1–reactive protein isolated by means of COS cell expression was found to be 84 and 77% homologous to mouse and human scavenger receptor MARCO mRNA, respectively. Transfection of COS cells with MARCO cDNA conferred mAb-inhibitable TiO2 binding. Hamster MARCO also mediates AM binding of unopsonized bacteria (67 ± 5 and 47 ± 4% inhibition of Escherichia coli and Staphylococcus aureus binding by mAb PAL-1). A polyclonal antibody to human MARCO identified the expected ∼70-kD band on Western blots of lysates of normal bronchoalveolar lavage (BAL) cells (>90% AMs) and showed strong immunolabeling of human AMs in BAL cytocentrifuge preparations and within lung tissue specimens. In normal mouse AMs, the anti-MARCO mAb ED31 also showed immunoreactivity and inhibited binding of unopsonized particles (e.g., TiO2 ∼40%) and bacteria. The novel function of binding unopsonized environmental dusts and pathogens suggests an important role for MARCO in the lungs' response to inhaled particles.