Huang Y, Border W A, Lawrence D A, Noble N A
Fibrosis Research Laboratory, Division of Nephrology, University of Utah School of Medicine, Salt Lake City, Utah 84108, USA.
Kidney Int. 2006 Aug;70(3):515-22. doi: 10.1038/sj.ki.5000353. Epub 2006 Jun 21.
Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P<0.001). Plasmin activity and zymography were consistent with ECM degradation. Plasmin inhibitors: alpha2-antiplasmin, aprotinin, and TA completely blocked PAI-1R's ability to normalize ECM degradation (P<0.001). Consistent with the in vitro results, TA reversed PAI-1R-induced reductions in glomerular fibrin and ECM accumulation. Other measures of disease severity were either unaltered or partially reversed. PAI-1R reduces pathological ECM accumulation, in large part through effectively competing with native PAI-1 thereby restoring plasmin generation and increasing plasmin-dependent degradation of matrix components.
纤溶酶原激活物抑制剂 -1（PAI -1）被认为具有促纤维化作用，它通过抑制纤溶酶的生成，从而减少病理性细胞外基质（ECM）的周转。我们最近发现一种突变的、无抑制作用的PAI -1（PAI -1R）可增加抗 Thy -1 肾炎模型肾小球的纤溶酶生成并减轻疾病。在此，我们进行了体外和体内研究，以确定增强的纤溶酶依赖性 ECM 降解是否是 PAI -1R 治疗作用的基础。大鼠系膜细胞（MCs）产生 3H 标记的 ECM。通过检测培养基中 3H 的释放量，来测定野生型 PAI -1（wt -PAI -1）和 PAI -1R 对新接种的 MCs 降解 ECM 的影响。在体内，在正常、未经治疗的患病大鼠以及用或不用纤溶酶/纤溶酶原抑制剂氨甲环酸（TA）治疗的 PAI -1R 处理的大鼠中评估抗 Thy -1 肾炎。当添加外源性纤溶酶原时，wt -PAI -1 完全抑制纤溶酶生成，并使 ECM 降解减少 76%。尽管单独的 PAI -1R 没有作用，但在 wt -PAI -1 存在的情况下，PAI -1R 以时间和剂量依赖性方式逆转了 wt -PAI -1 对 ECM 降解的抑制作用（P<0.001）。纤溶酶活性和酶谱分析结果与 ECM 降解情况一致。纤溶酶抑制剂：α2 -抗纤溶酶、抑肽酶和 TA 完全阻断了 PAI -1R 使 ECM 降解恢复正常的能力（P<0.001）。与体外结果一致，TA 逆转了 PAI -1R 诱导的肾小球纤维蛋白和 ECM 积累的减少。疾病严重程度的其他指标要么未改变，要么部分逆转。PAI -1R 减少病理性 ECM 积累，很大程度上是通过与天然 PAI -1 有效竞争，从而恢复纤溶酶生成并增加基质成分的纤溶酶依赖性降解。
