Cosio F G, Sedmak D D, Nahman N S
Department of Internal Medicine and Pathology, Ohio State University, Columbus.
Kidney Int. 1990 Nov;38(5):886-95. doi: 10.1038/ki.1990.287.
In the present study we evaluated the distribution of cell adhesion molecules, referred as very late antigens (VLA), in the normal human kidney and in mesangial cells in culture (MC). In addition, we assessed the functional properties of VLA proteins on MC. Normal human kidney and MC were stained by immunoperoxidase with mouse monoclonal antibodies to VLA proteins. We demonstrated that VLA-3, a protein that binds FN, laminin and collagen, is the predominant VLA protein in the human glomerulus and on MC. VLA-3 is located in the mesangium and on the glomerular visceral epithelial cell and endothelial cell surfaces in contact with the glomerular basement membrane. VLA-1 was demonstrated in the glomerular mesangium and VLA-5, an FN specific receptor, was present in the mesangium on glomerular endothelial cells and on MC. VLA-2 and VLA-4 were not present in the normal glomerulus nor on MC. In functional studies we evaluated the binding of MC to FN coated surfaces and the binding and phagocytosis of FN coated fluorescent beads by MC. We showed that MC bind to FN coated surfaces and that the binding is inhibited by anti-FN antibodies, EDTA and peptides containing the amino acid sequence Arg-Gly-Asp (RGD). In addition, anti-VLA-5 but not anti-VLA-3 antibodies inhibited significantly the binding of MC to FN, MC demonstrated binding and phagocytosis of FN coated beads and, purified FN inhibited both phenomena. By affinity chromatography and immunoprecipitation we demonstrated that MC FN binding proteins and MC VLA proteins are composed of two distinct protein chains that have Mr characteristics similar to those of normal human fibroblasts VLA proteins. In conclusion, the glomerular distribution of VLA-3 suggests that this protein is primarily involved on the adhesion of glomerular cells to basement membranes and matrix. MC FN receptors (VLA-5) mediate the binding of MC to FN and could mediate the phagocytosis of FN coated antigen or immune complexes by mesangial cells.
在本研究中，我们评估了细胞黏附分子（称为极晚期抗原，VLA）在正常人类肾脏及培养的系膜细胞（MC）中的分布。此外，我们还评估了VLA蛋白在MC上的功能特性。用针对VLA蛋白的小鼠单克隆抗体通过免疫过氧化物酶法对正常人类肾脏和MC进行染色。我们证明，VLA - 3这种能结合纤连蛋白（FN）、层粘连蛋白和胶原蛋白的蛋白，是人类肾小球及MC上的主要VLA蛋白。VLA - 3位于系膜以及与肾小球基底膜接触的肾小球脏层上皮细胞和内皮细胞表面。在肾小球系膜中检测到了VLA - 1，而VLA - 5（一种FN特异性受体）存在于肾小球内皮细胞和MC的系膜中。VLA - 2和VLA - 4在正常肾小球及MC中均未出现。在功能研究中，我们评估了MC与包被FN的表面的结合以及MC对包被FN的荧光珠的结合和吞噬作用。我们发现MC能与包被FN的表面结合，且这种结合可被抗FN抗体、乙二胺四乙酸（EDTA）以及含有精氨酸 - 甘氨酸 - 天冬氨酸（RGD）氨基酸序列的肽所抑制。此外，抗VLA - 5抗体而非抗VLA - 3抗体能显著抑制MC与FN的结合，MC表现出对包被FN的珠子的结合和吞噬作用，并且纯化的FN能抑制这两种现象。通过亲和层析和免疫沉淀，我们证明MC的FN结合蛋白和MC的VLA蛋白由两条不同的蛋白链组成，其分子量特征与正常人类成纤维细胞的VLA蛋白相似。总之，VLA - 3在肾小球中的分布表明该蛋白主要参与肾小球细胞与基底膜及基质的黏附。MC的FN受体（VLA - 5）介导MC与FN的结合，并可能介导系膜细胞对包被FN的抗原或免疫复合物的吞噬作用。
