Cheung P K, Baller J F, Bakker W W
Department of Pathology, University of Groningen, The Netherlands.
Nephrol Dial Transplant. 1996 Nov;11(11):2185-91. doi: 10.1093/oxfordjournals.ndt.a027135.
The pathogenesis of albuminuria in minimal change disease (MCD) is unknown. A human plasma factor (denoted as 100KF) is able to induce minimal change-like glomerular alterations, i.e. loss of glomerular sialoglycoproteins and decreased expression of glomerular ecto-ATPase, following in vitro incubation with kidney tissue. In addition, increased (selective) permeability for plasma proteins occurs after perfusion of 100KF into the rat kidney ex vivo. As in kidney tissue from subjects with minimal change disease, subendothelial injury has also been observed, i.e. reduced anionic sites in the lamina rara interna, the question was raised whether injury induced by the plasma factor 100KF involves vascular endothelium or subendothelial matrix of the glomerular capillary wall.
Permeability studies were carried out by using confluent endothelial monolayers (HUVEC) cultured on a standard two-compartment system. The permeability for a macromolecular marker (horse radish peroxidase) was tested following incubation of the monolayers with either the native plasma factor 100KF or the control factor (heat-inactivated 100KF), in combination with histochemical evaluation of the cells for ecto-ATPase expression. Also quantification of glomerular anionic sites at the ultrastructural level was carried out, after ex vivo perfusion of 100KF or control factor into rat kidneys.
The plasma factor 100KF is able to increase the permeability of human endothelial monolayers for macromolecules in a dose-dependent manner (relative increase 122.4 +/- 24, 178.4 +/- 34 and 236.1 +/- 58% after preincubation with 0.05; 0.5 and 1.5 mg/ml 100KF respectively), concomitant with induction of minimal change-like histochemical alterations such as reduced expression of ecto-ATPase. The number of anionic sites in the lamina rara interna of the glomerular capillary wall is significantly diminished following perfusion with the plasma factor 100KF versus control factor (7.58 +/- 1.60 versus 12.57 +/- 2.05 per 1000 nm; P < or = 0.02); in contrast to the lamina rara externa (22.71 +/- 3.15 versus 22.27 +/- 2.92 per 1000 nm; statistically not significant).
Endothelial cells and subendothelial matrix along the glomerular filtration barrier may be considered as target structures for the plasma factor 100KF, leading to initial minimal change-like alterations associated with glomerular albumin leakage.
微小病变病（MCD）中蛋白尿的发病机制尚不清楚。一种人血浆因子（称为100KF）在与肾组织进行体外孵育后，能够诱导微小病变样的肾小球改变，即肾小球唾液糖蛋白的丢失和肾小球外切ATP酶表达的降低。此外，将100KF灌注到大鼠离体肾脏后，血浆蛋白的（选择性）通透性增加。由于在微小病变病患者的肾组织中也观察到内皮下损伤，即内皮下层阴离子位点减少，因此有人提出血浆因子100KF诱导的损伤是否涉及肾小球毛细血管壁的血管内皮或内皮下基质。
使用在标准双室系统上培养的汇合内皮单层（人脐静脉内皮细胞）进行通透性研究。在用天然血浆因子100KF或对照因子（热灭活的100KF）孵育单层后，测试对大分子标志物（辣根过氧化物酶）的通透性，并结合对细胞外切ATP酶表达的组织化学评估。在将100KF或对照因子灌注到大鼠肾脏离体后，还在超微结构水平上对肾小球阴离子位点进行了定量。
血浆因子100KF能够以剂量依赖的方式增加人内皮单层对大分子的通透性（分别用0.05、0.5和1.5mg/ml 100KF预孵育后，相对增加122.4±24、178.4±34和236.1±58%），同时诱导微小病变样的组织化学改变，如外切ATP酶表达降低。与对照因子相比，用血浆因子100KF灌注后，肾小球毛细血管壁内皮下层的阴离子位点数量显著减少（每1000nm分别为7.58±1.60和12.57±2.05；P≤0.02）；与外皮下层相比则相反（每1000nm分别为22.71±3.15和22.27±2.92；无统计学意义）。
肾小球滤过屏障处的内皮细胞和内皮下基质可能被视为血浆因子100KF的靶结构，导致与肾小球白蛋白渗漏相关的初始微小病变样改变。
