Thurston G, Baluk P, Hirata A, McDonald D M
Department of Anatomy, University of California, San Francisco 94143-0452, USA.
Am J Physiol. 1996 Dec;271(6 Pt 2):H2547-62. doi: 10.1152/ajpheart.1996.271.6.H2547.
Plasma leakage in inflammation results from intercellular gaps that form in the endothelium of venules. These gaps and related morphological changes in endothelial cells are not readily seen by light microscopy. In this study we sought to visualize such changes by using the selective binding properties of plant lectins. Acute inflammation was induced in the trachea of pathogen-free F344 rats by injecting substance P intravenously, and 1, 3, or 10 min later the vasculature was perfused with fixative followed by a biotinylated lectin. Lectin binding was localized by avidinbiotin complex-peroxidase histochemistry and viewed in tracheal whole mounts by differential-interference contrast microscopy. The binding patterns of the 20 lectins tested fell into 4 groups. Most of the lectins either bound uniformly to the endothelium of normal and inflamed venules (group 1, e.g., Lycopersicon esculentum lectin) or bound weakly or not at all to venules (group 2, e.g., Maackia amurensis I lectin). The uniform binding of group 1 lectins not only revealed the overall vascular architecture but also made visible intercellular gaps and fingerlike processes at endothelial cell borders in inflamed venules. In postcapillary venules after substance P, the fingerlike processes were present along an average of 32% of the endothelial cell perimeter at 1 min, 25% at 3 min, and 7% at 10 min, compared with a baseline value of 2%. A third group of lectins (group 3, e.g., concanavalin A) bound selectively to focal patches of inflamed venules but bound weakly to normal venules. The fourth group (group 4, e.g., Ricinus communis I lectin) bound preferentially to focal patches in inflamed venules and also bound uniformly to normal venules. The focal binding of group 3 and 4 lectins coincided with sites of plasma leakage marked by extravasation of the particulate tracer monastral blue and was associated with subendothelial components of the vessel wall. We conclude that selected lectins reveal novel features of focal sites of plasma leakage, endothelial gaps, and fingerlike processes at endothelial cell borders in inflamed venules.
炎症中的血浆渗漏是由小静脉内皮细胞间形成的细胞间隙导致的。这些间隙以及内皮细胞相关的形态学变化在光学显微镜下不易观察到。在本研究中，我们试图利用植物凝集素的选择性结合特性来观察此类变化。通过静脉注射P物质，在无病原体的F344大鼠气管中诱导急性炎症，1、3或10分钟后用固定剂灌注血管系统，随后灌注生物素化凝集素。通过抗生物素蛋白-生物素复合物-过氧化物酶组织化学对凝集素结合进行定位，并通过微分干涉相差显微镜在气管整装标本中观察。所测试的20种凝集素的结合模式分为4组。大多数凝集素要么均匀地结合到正常和炎症小静脉的内皮上（第1组，例如番茄凝集素），要么与小静脉结合较弱或根本不结合（第2组，例如山黧豆凝集素I）。第1组凝集素的均匀结合不仅揭示了整体血管结构，还使炎症小静脉内皮细胞边界处的细胞间隙和指状突起可见。在注射P物质后的毛细血管后小静脉中，指状突起在1分钟时平均沿内皮细胞周长的32%存在，3分钟时为25%，10分钟时为7%，而基线值为2%。第三组凝集素（第3组，例如伴刀豆球蛋白A）选择性地结合到炎症小静脉的局灶性斑块上，但与正常小静脉结合较弱。第四组（第4组，例如蓖麻凝集素I）优先结合到炎症小静脉的局灶性斑块上，并且也均匀地结合到正常小静脉上。第3组和第4组凝集素的局灶性结合与由颗粒示踪剂单星蓝外渗标记的血浆渗漏部位一致，并与血管壁的内皮下成分相关。我们得出结论，选定的凝集素揭示了炎症小静脉中血浆渗漏的局灶部位、内皮间隙以及内皮细胞边界处指状突起的新特征。
