Kootstra C J, Bergijk E C, Veninga A, Prins F A, de Heer E, Abrahamson D R, Bruijn J A
Department of Pathology, University of Leiden, The Netherlands.
Am J Pathol. 1995 Aug;147(2):476-88.
Previous studies have revealed quantitative alterations in laminin-1 expression at the mRNA and protein levels during the development of glomerulonephritis and glomerulosclerosis in chronic graft-versus-host disease in mice, a model for lupus nephritis. We have now studied the qualitative alterations in laminin expression with two monoclonal antibodies that recognize epitopes on either the E8 or the P1 fragment of laminin-1. Both of these fragments are involved in cell-matrix and matrix-matrix interactions. In normal glomeruli these laminin epitopes are present only in the mesangial matrix; during embryogenesis, however, they are also present in the glomerular basement membrane. The distribution of laminin epitopes was first studied by using immunofluorescence in kidneys of mice with graft-versus-host disease at different points in time after disease induction. Reflection contrast and immunoelectron microscopy were performed after in vivo injection of the horseradish peroxidase-coupled monoclonal antibodies. In glomeruli of mice 8 weeks after disease induction, both injected antibodies bound specifically in electron-dense immune deposits in the mesangium and subepithelially along the glomerular basement membrane as well as in the expanded mesangial matrix. At 11 and 12 weeks after disease induction, when focal and segmental glomerulosclerosis had developed, the antibodies additionally bound in the matrix subendothelially along the glomerular basement membrane and at the periphery of end-stage sclerotic lesions. To study changes in the distribution of laminin epitopes over time, mice were injected with either monoclonal antibody before induction of graft-versus-host disease. The antibodies were detected 8 and 12 weeks later in the mesangial matrix of mice with lupus nephritis. Once segmental glomerulosclerosis had developed, the antibodies were additionally detected within the thickened glomerular capillary wall. The specific binding of anti-laminin monoclonal antibodies in electron-dense immune deposits further substantiates the hypothesis that anti-laminin autoantibodies participate in glomerular immune complex formation in this model, as suggested by earlier studies. Furthermore, our results show that the distribution of glomerular laminin epitopes in the matrix is altered during the development of glomerular disease. These changes in the structure of the glomerular basement membrane may contribute to the abnormal cell-matrix and matrix-matrix interactions during the development of glomerular disease in this model for lupus nephritis.
先前的研究已经揭示，在小鼠慢性移植物抗宿主病（狼疮性肾炎的一种模型）中，肾小球肾炎和肾小球硬化症发展过程中，层粘连蛋白-1在mRNA和蛋白质水平上存在定量改变。我们现在用两种单克隆抗体研究了层粘连蛋白表达的定性改变，这两种抗体识别层粘连蛋白-1的E8或P1片段上的表位。这两个片段都参与细胞-基质和基质-基质相互作用。在正常肾小球中，这些层粘连蛋白表位仅存在于系膜基质中；然而，在胚胎发生过程中，它们也存在于肾小球基底膜中。首先通过免疫荧光法研究了疾病诱导后不同时间点患有移植物抗宿主病的小鼠肾脏中层粘连蛋白表位的分布。在体内注射辣根过氧化物酶偶联的单克隆抗体后进行反射对比和免疫电子显微镜检查。在疾病诱导8周后的小鼠肾小球中，两种注射的抗体都特异性地结合在系膜和沿肾小球基底膜的上皮下电子致密免疫沉积物以及扩张的系膜基质中。在疾病诱导11周和12周后，当局灶性节段性肾小球硬化症发展时，抗体还结合在沿肾小球基底膜的内皮下基质以及终末期硬化病变的周边。为了研究层粘连蛋白表位分布随时间的变化，在诱导移植物抗宿主病之前给小鼠注射其中一种单克隆抗体。8周和12周后在患有狼疮性肾炎的小鼠系膜基质中检测到这些抗体。一旦节段性肾小球硬化症发展，在增厚的肾小球毛细血管壁内也检测到这些抗体。抗层粘连蛋白单克隆抗体在电子致密免疫沉积物中的特异性结合进一步证实了先前研究所提出的假说，即在该模型中抗层粘连蛋白自身抗体参与肾小球免疫复合物的形成。此外，我们的结果表明，在肾小球疾病发展过程中，肾小球层粘连蛋白表位在基质中的分布发生了改变。在这个狼疮性肾炎模型中，肾小球基底膜结构的这些变化可能导致肾小球疾病发展过程中异常的细胞-基质和基质-基质相互作用。
