Kato Hiroyuki, Duarte Sergio, Liu Daniel, Busuttil Ronald W, Coito Ana J
The Dumont-UCLA Transplant Center, Division of Liver and Pancreas Transplantation, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States of America.
PLoS One. 2015 Sep 10;10(9):e0137642. doi: 10.1371/journal.pone.0137642. eCollection 2015.
Hepatic ischemia and reperfusion injury (IRI) is an inflammatory condition and a significant cause of morbidity and mortality after surgery. Matrix metalloproteinases (MMPs) have been widely implicated in the pathogenesis of inflammatory diseases. Among the different MMPs, gelatinases (MMP-2 and MMP-9) are within the most prominent MMPs detected during liver IRI. While the role of MMP-9 in liver damage has been fairly documented, direct evidence of the role for MMP-2 activity in hepatic IRI remains to be established. Due to the lack of suitable inhibitors to target individual MMPs in vivo, gene manipulation is as an essential tool to assess MMP direct contribution to liver injury. Hence, we used MMP-2-/- deficient mice and MMP-2+/+ wild-type littermates to examine the function of MMP-2 activity in hepatic IRI. MMP-2 expression was detected along the sinusoids of wild-type livers before and after surgery and in a small population of leukocytes post-IRI. Compared to MMP-2+/+ mice, MMP-2 null (MMP-2-/-) mice showed exacerbated liver damage at 6, 24, and 48 hours post-reperfusion, which was fatal in some cases. MMP-2 deficiency resulted in upregulation of MMP-9 activity, spontaneous leukocyte infiltration in naïve livers, and amplified MMP-9-dependent transmigration of leukocytes in vitro and after hepatic IRI. Moreover, complete loss of MMP-2 activity impaired the degradation of poly (ADP-ribose) polymerase (PARP-1) in extensively damaged livers post-reperfusion. However, the administration of a PARP-1 inhibitor to MMP-2 null mice restored liver preservation to almost comparable levels of MMP-2+/+ mice post-IRI. Deficient PARP-1 degradation in MMP-2-null sinusoidal endothelial cells correlated with their increased cytotoxicity, evaluated by the measurement of LDH efflux in the medium. In conclusion, our results show for the first time that MMP-2 gene deletion exacerbates liver IRI. Moreover, they offer new insights into the MMP-2 modulation of inflammatory responses, which could be relevant for the design of new pharmacological MMP-targeted agents to treat hepatic IRI.
肝缺血再灌注损伤（IRI）是一种炎症状态，是术后发病和死亡的重要原因。基质金属蛋白酶（MMPs）已被广泛认为与炎症性疾病的发病机制有关。在不同的MMPs中，明胶酶（MMP-2和MMP-9）是肝IRI期间检测到的最主要的MMPs。虽然MMP-9在肝损伤中的作用已有相当多的文献记载，但MMP-2活性在肝IRI中的作用的直接证据仍有待确立。由于缺乏在体内靶向单个MMPs的合适抑制剂，基因操作是评估MMPs对肝损伤直接作用的重要工具。因此，我们使用MMP-2-/-缺陷小鼠和MMP-2+/+野生型同窝小鼠来研究MMP-2活性在肝IRI中的功能。在手术前后的野生型肝脏的肝血窦以及IRI后的一小部分白细胞中检测到MMP-2表达。与MMP-2+/+小鼠相比，MMP-2基因敲除（MMP-2-/-）小鼠在再灌注后6、24和48小时显示出更严重的肝损伤，在某些情况下是致命的。MMP-2缺乏导致MMP-9活性上调、未损伤肝脏中自发的白细胞浸润以及体外和肝IRI后MMP-9依赖性白细胞迁移增加。此外，MMP-2活性的完全丧失损害了再灌注后广泛受损肝脏中聚（ADP-核糖）聚合酶（PARP-1）的降解。然而，给MMP-2基因敲除小鼠施用PARP-1抑制剂可使肝脏保存恢复到与IRI后MMP-2+/+小鼠几乎相当的水平。MMP-2基因敲除的肝血窦内皮细胞中PARP-1降解不足与其细胞毒性增加相关，通过测量培养基中的乳酸脱氢酶外流来评估。总之，我们的结果首次表明MMP-2基因缺失会加剧肝IRI。此外，它们为MMP-2对炎症反应的调节提供了新的见解，这可能与设计治疗肝IRI的新型MMP靶向药物有关。
