Haslinger Bettina, Goedde Martin F, Toet Karin H, Kooistra Teake
Gaubius Laboratory, TNO Prevention and Health, Leiden, The Netherlands.
Kidney Int. 2002 Nov;62(5):1611-9. doi: 10.1046/j.1523-1755.2002.00601.x.
The continuous physical and chemical irritation of the peritoneum in peritoneal dialysis patients can result in a nonbacterial serositis with increased fibrin deposition, thus promoting peritoneal fibrosis and adhesion development. By expressing the fibrinolytic enzyme tissue-type plasminogen activator (t-PA) and its specific inhibitor, plasminogen activator inhibitor-1 (PAI-1), human peritoneal mesothelial cells (HMC) play an important role in regulating peritoneal fibrinolysis.
Cultured HMC were used to examine the effect of a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, simvastatin, on the expression of t-PA and PAI-1. Antigen concentrations in the cell supernatants were measured by ELISA and Northern blot analysis was conducted for mRNA expression.
Simvastatin time- and concentration-dependently increased t-PA and decreased PAI-1 synthesis, reaching maximal effects after 48 hours, when simvastatin (1 micromol/L) increased t-PA levels 5.1 +/- 0.1-fold and suppressed PAI-1 levels 2.6 +/- 0.2-fold. This was accompanied by a twofold increase in mesothelial cell-associated t-PA activity. Qualitatively similar results were obtained in cultured human endothelial cells, but the effects were less pronounced and required higher simvastatin concentrations. Northern blot analysis revealed that the action of simvastatin on t-PA and PAI-1 expression in HMC can be explained by parallel changes in t-PA and PAI-1 mRNA. The effects of simvastatin were prevented in the presence of mevalonate and geranylgeraniol, suggesting that the effect of simvastatin on t-PA and PAI-1 synthesis is mediated through geranylgeranyl-modified intermediates. Experiments using specific inhibitors of geranylgeranylated Rho GTPases excluded a role of members of this family of small GTP-binding proteins in simvastatin action in HMC. The effects of simvastatin on t-PA and PAI-1 expression as well as on cell shape were completely mimicked by cytochalasin D, a disrupter of cellular actin filaments, but not by colchicine, a disrupter of microtubules.
In conclusion, the cholesterol-lowering drug simvastatin is an effective stimulator of local peritoneal fibrinolytic activity, as it increases t-PA and decreases PAI-1 production in mesothelial cells by a mechanism involving geranylgeranyl-modified intermediates and actin skeleton perturbation. These results provide a new rationale to prevent peritoneal fibrin deposition and adhesion development in peritoneal dialysis patients.
腹膜透析患者腹膜受到持续的物理和化学刺激可导致非细菌性浆膜炎，纤维蛋白沉积增加，从而促进腹膜纤维化和粘连形成。人腹膜间皮细胞（HMC）通过表达纤溶酶组织型纤溶酶原激活剂（t-PA）及其特异性抑制剂纤溶酶原激活剂抑制剂-1（PAI-1），在调节腹膜纤维蛋白溶解中起重要作用。
使用培养的HMC检测3-羟基-3-甲基戊二酰辅酶A还原酶抑制剂辛伐他汀对t-PA和PAI-1表达的影响。通过ELISA测量细胞上清液中的抗原浓度，并进行Northern印迹分析以检测mRNA表达。
辛伐他汀在时间和浓度上均依赖性地增加t-PA的合成并降低PAI-1的合成，48小时后达到最大效应，此时辛伐他汀（1μmol/L）使t-PA水平增加5.1±0.1倍，抑制PAI-1水平2.6±0.2倍。这伴随着间皮细胞相关t-PA活性增加两倍。在培养的人内皮细胞中获得了定性相似的结果，但效应不太明显，且需要更高的辛伐他汀浓度。Northern印迹分析表明，辛伐他汀对HMC中t-PA和PAI-1表达的作用可通过t-PA和PAI-1 mRNA的平行变化来解释。在甲羟戊酸和香叶基香叶醇存在的情况下，辛伐他汀的作用被阻断，这表明辛伐他汀对t-PA和PAI-1合成的作用是通过香叶基香叶基修饰的中间体介导的。使用香叶基香叶基化的Rho GTPases特异性抑制剂的实验排除了这个小GTP结合蛋白家族成员在辛伐他汀对HMC作用中的作用。细胞松弛素D（一种细胞肌动蛋白丝破坏剂）完全模拟了辛伐他汀对t-PA和PAI-1表达以及细胞形态的影响，但秋水仙碱（一种微管破坏剂）没有这种作用。
总之，降胆固醇药物辛伐他汀是局部腹膜纤维蛋白溶解活性的有效刺激剂，因为它通过涉及香叶基香叶基修饰的中间体和肌动蛋白骨架扰动的机制增加间皮细胞中t-PA的产生并降低PAI-1的产生。这些结果为预防腹膜透析患者腹膜纤维蛋白沉积和粘连形成提供了新的理论依据。
