Floege J, Johnson R J, Gordon K, Yoshimura A, Campbell C, Iruela-Arispe L, Alpers C E, Couser W G
Department of Medicine, University of Washington, Seattle.
Kidney Int. 1992 Sep;42(3):573-85. doi: 10.1038/ki.1992.321.
Chronic progressive membranous nephropathy (MN) in humans is characterized by thickening of the glomerular basement membrane (GBM) with formation of spikes which contain laminin and other extracellular matrix (ECM) proteins. We have utilized two models of MN in the rat (active and passive Heymann nephritis, AICN, PHN) to define the sequential changes in composition of GBM as they relate to changes in glomerular gene expression for ECM components, altered permeability and morphological changes. Renal biopsies obtained during the course of AICN and PHN were immunostained for various ECM proteins and total glomerular RNA was hybridized with cDNA probes specific for laminin B2-chain, s-laminin, and types I and IV collagen. In addition, the ability of anti-glomerular epithelial cell (GEC) antibody and complement on rat GEC in culture to induce laminin release or laminin and s-laminin mRNA expression was determined. The results demonstrate that at weeks 12, 16, and 20 of AICN, immunostaining for laminin, s-laminin, fibronectin, entactin, and heparan sulfate proteoglycan increased in the GBM in a spike-like pattern. Concomitantly, glomerular mRNA levels of laminin B2-chain and of s-laminin increased. Type IV collagen protein and gene expression remained unchanged or decreased. No glomerular immunostaining for type I collagen occurred during AICN despite increased expression of mRNA for this collagen type. In contrast to AICN, in PHN no pronounced changes of the glomerular ECM occurred, except for transient expression of type I collagen mRNA in whole glomerular RNA and type I collagen protein the GEC cytoplasm. Stimulation of GEC in culture with anti-GEC antibody and complement also failed to induce transcription of laminin or s-laminin mRNA or the release of laminin protein. These findings suggest that the polyantigenic expansion of GBM which occurs in chronic experimental MN may be stimulated by factors different from the C5b-9 mediated processes that cause the initial proteinuria.
人类慢性进行性膜性肾病（MN）的特征是肾小球基底膜（GBM）增厚，并形成含有层粘连蛋白和其他细胞外基质（ECM）蛋白的钉突。我们利用大鼠的两种MN模型（主动和被动型Heymann肾炎，AICN，PHN）来确定GBM成分的顺序变化，这些变化与ECM成分的肾小球基因表达变化、通透性改变和形态学变化相关。在AICN和PHN病程中获取的肾活检组织针对各种ECM蛋白进行免疫染色，并且将总的肾小球RNA与层粘连蛋白B2链、s -层粘连蛋白以及I型和IV型胶原的特异性cDNA探针杂交。此外，还测定了培养的大鼠肾小球上皮细胞（GEC）上的抗肾小球上皮细胞抗体和补体诱导层粘连蛋白释放或层粘连蛋白和s -层粘连蛋白mRNA表达的能力。结果表明，在AICN的第12、16和20周，GBM中层粘连蛋白、s -层粘连蛋白、纤连蛋白、巢蛋白和硫酸乙酰肝素蛋白聚糖的免疫染色呈钉突样增加。同时，层粘连蛋白B2链和s -层粘连蛋白的肾小球mRNA水平增加。IV型胶原蛋白和基因表达保持不变或下降。尽管该型胶原的mRNA表达增加，但在AICN期间未出现I型胶原的肾小球免疫染色。与AICN相反，在PHN中，除了在整个肾小球RNA中I型胶原mRNA的短暂表达以及GEC细胞质中I型胶原蛋白的表达外，肾小球ECM未发生明显变化。用抗GEC抗体和补体刺激培养的GEC也未能诱导层粘连蛋白或s -层粘连蛋白mRNA的转录或层粘连蛋白的释放。这些发现表明，慢性实验性MN中发生的GBM多抗原性扩展可能受到不同于导致初始蛋白尿的C5b - 9介导过程的因素刺激。
