Eddy A A, Giachelli C M
Division of Nephrology, Hospital for Sick Children, University of Toronto, Ontario, Canada.
Kidney Int. 1995 Jun;47(6):1546-57. doi: 10.1038/ki.1995.218.
Rats with significant proteinuria induced by daily injections of bovine serum albumin develop interstitial inflammation and fibrosis. The present study was designed to investigate the molecular basis of interstitial monocyte (Mø) recruitment and early interstitial fibrosis. Groups of rats were sacrificed after one, two and three weeks. Despite an increase in interstitial Mø at week 1, whole kidney mRNA levels were not elevated for monocyte chemoattractant protein-1 (MCP-1), osteopontin or vascular cell adhesion molecule-1 (VCAM-1). Only osteopontin mRNA levels were significantly elevated in the renal cortex at four days. At two and three weeks, MCP-1 and osteopontin mRNA levels were increased and the proteins showed distinct tubular patterns of distribution. By immunostaining increased expression of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) was restricted to their presence or the surface of the interstitial inflammatory cells. TGF-beta 1 mRNA levels were increased at weeks 1, 2 and 3 (2.1, 2.9, 3.6x); interstitial and occasional cortical tubular cells expressed TGF-beta 1 mRNA and protein. There was a progressive rise in the number of cortical interstitial fields with increased staining for collagen (col) 1 (18, 29, 44%), col III (39, 61, 63%), col IV (7, 13, 29%), laminin (4, 10, 30%), fibronectin (14, 28, 37%), tenascin (19, 22, 14%) and in total renal col measured biochemically (1.1, 1.4, 2.0x) at weeks 1, 2 and 3, respectively. Renal matrix protein mRNA levels were variable and not always predictive of fibrosis. Only col I and tenascin levels were increased at week 1; all matrix protein mRNA levels except col IV were increased at week 2; but only tenascin, laminin and col IV mRNA levels remained elevated at three weeks. Plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metallo-proteinases (TIMP)-1 mRNA levels were significantly increased at two weeks. During the three weeks there was no change in urokinase, stromelysin or TIMP-3 mRNA levels. These results suggest that both increased matrix protein synthesis and altered matrix remodeling/degradation contribute to the final interstitial fibrogenic process in rats with protein-overload proteinuria. Mø, one of the sources of TGF-beta 1, infiltrate the interstitium by complex recruitment mechanisms which may depend in part on osteopontin, ICAM-1 and VCAM-1 expression.
通过每日注射牛血清白蛋白诱导出显著蛋白尿的大鼠会出现间质炎症和纤维化。本研究旨在探讨间质单核细胞（Mø）募集及早期间质纤维化的分子基础。在1周、2周和3周后处死大鼠组。尽管第1周时间质Mø增加，但单核细胞趋化蛋白-1（MCP-1）、骨桥蛋白或血管细胞黏附分子-1（VCAM-1）的全肾mRNA水平并未升高。仅在第4天时肾皮质中的骨桥蛋白mRNA水平显著升高。在第2周和第3周时，MCP-1和骨桥蛋白mRNA水平升高，且这些蛋白呈现出不同的肾小管分布模式。通过免疫染色发现，VCAM-1和细胞间黏附分子-1（ICAM-1）表达的增加仅限于间质炎症细胞的存在或其表面。转化生长因子-β1（TGF-β1）mRNA水平在第1周、第2周和第3周时升高（分别为2.1、2.9、3.6倍）；间质及偶尔的皮质肾小管细胞表达TGF-β1 mRNA和蛋白。随着皮质间质区域数量的逐渐增加，I型胶原（col）（18%、29%、44%）、III型胶原（39%、61%、63%）、IV型胶原（7%、13%、29%）、层粘连蛋白（4%、10%、30%）、纤连蛋白（14%、28%、37%）、腱生蛋白（19%、22%、14%）的染色增加，且在第1周、第2周和第3周时，通过生化方法测定的总肾胶原含量分别增加（1.1、1.4、2.0倍）。肾基质蛋白mRNA水平各不相同，并不总是能预测纤维化。仅在第1周时I型胶原和腱生蛋白水平升高；在第2周时，除IV型胶原外的所有基质蛋白mRNA水平均升高；但在第3周时，仅腱生蛋白、层粘连蛋白和IV型胶原mRNA水平仍保持升高。纤溶酶原激活物抑制剂-1（PAI-1）和金属蛋白酶组织抑制剂（TIMP）-1 mRNA水平在第2周时显著升高。在这三周期间，尿激酶、基质溶解素或TIMP-3 mRNA水平没有变化。这些结果表明，基质蛋白合成增加和基质重塑/降解改变均有助于蛋白超负荷蛋白尿大鼠最终的间质纤维化过程。Mø作为TGF-β1的来源之一，通过复杂的募集机制浸润间质，这一机制可能部分取决于骨桥蛋白、ICAM-1和VCAM-1的表达。
