Role of plasminogen activator inhibitor-1 in mediating age-related fibrosis

描述（由申请人提供）：心血管老化导致心脏纤维化、舒张功能障碍和心肌梗死（MI）后伤口愈合减弱。虽然许多研究表明纤溶酶原激活物抑制剂-1 （PAI-1）的增加与衰老有关，但没有一项研究直接研究PAI-1介导的胶原转换抑制的可能机制。该研究旨在确定PAI-1在调节年龄相关性心脏纤维化中的作用。PAI-1的年龄依赖性增加与基质金属蛋白酶（MMP）活性降低、胶原沉积增加和炎症反应减弱相关。由于ECM降解和成纤维细胞迁移受损，心肌梗死后MMP活性降低可能通过增加胶原沉积和减少炎症反应导致心室纤维化。分离的大鼠心脏成纤维细胞（CFs）将用于研究PAI-1释放与胶原沉积和CF迁移的潜在影响之间的关系。本研究的第一个目的是探究CFs产生和释放的PAI-1是否通过抑制MMP激活而增加胶原沉积。总MMPs和活性MMPs将通过Western blotting、酶谱和ELISA检测。第二个目的是比较从年轻大鼠和老年大鼠分离的CFs中PAI-1的表达，以检查表达是否随着年龄的增长而增加，并负责增加胶原积累。PAI-1随着年龄的增长被认为会减弱MMP的活性。这反过来减少胶原降解，也可能抑制CF迁移。最后，本研究的第三个目的将使用离体大鼠缺血再灌注模型。这提供了一个系统来确定老年心脏中PAI-1的表达是否基本增加，以及缺血应激后PAI-1是否在生理相关浓度上上调。PAI-1对MMP活性的急性抑制可能解释了老年人心肌梗死后炎症和伤口愈合反应的减弱。总之，这些发现可能确定了一种新的依赖PAI-1的机制，在这种机制中，衰老的心脏更容易发生纤维化和缺血损伤后伤口愈合减弱。

DESCRIPTION (provided by applicant): Cardiovascular aging results in cardiac fibrosis, diastolic dysfunction, and attenuated wound healing post-myocardial infarction (MI). While numerous studies have correlated increases in plasminogen activator inhibitor-1 (PAI-1) with aging, none have directly examined possible mechanisms of PAI-1-mediated inhibition of collagen turnover. The proposed study seeks to identify a role of PAI-1 in regulating age-related cardiac fibrosis. Age-dependent increases of PAI-1 correlate with decreased matrix metalloprotease (MMP) activity, increased collagen deposition, and blunted inflammatory response. As a consequence of impaired ECM degradation and fibroblast migration, the reduction in MMP activity may cause ventricular fibrosis by increasing collagen deposition and diminished inflammatory responses post-MI. Isolated rat cardiac fibroblasts (CFs) will be used to investigate the relationship between PAI-1 release and potential effects on collagen deposition and CF migration. The first aim of this study asks whether PAI-1 produced and released by CFs increases collagen deposition by inhibiting MMP activation. Total and active MMPs will be assayed in CFs by Western blotting, zymography, and ELISA. The second aim compares PAI-1 expression in CFs isolated from young and aged rats to examine whether expression increases with age and is responsible for increased collagen accumulation. The increase of PAI-1 with age is hypothesized to attenuate MMP activity. This in turn decreases collagen degradation and may also inhibit CF migration. Finally, the third aim of the study will use an ex vivo rat ischemia-reperfusion model. This provides a system to ascertain whether PAI-1 expression is increased basally in aged hearts and whether PAI-1 is up-regulated in physiologically relevant concentrations following ischemic stress. Acute inhibition of MMP activity by PAI-1 may explain the attenuated inflammatory and wound healing responses post-MI seen in aged individuals. Together, these findings may identify a novel PAI-1 dependent mechanism in which aged hearts are more prone to both fibrosis and attenuated wound healing following ischemic damage.