Matrix Metalloproteinases in Hepatic Ischemia and Reperfusion Injury

肝缺血再灌注损伤(IRI)发生在所有移植肝脏中，在创伤、休克和择期手术中。 肝脏供血暂时中断的外科手术。IRI导致高达10%的早期移植 失败，并可能导致显著更高的急性和慢性排斥反应发生率。数以千计 每年都有病人在等待器官捐赠者的过程中死亡。这一悲观的情景，连同 肥胖在人口中的显著流行，导致了对使用次优药物的需求增加 由于脂肪变性肝脏对IRI的高度易感性，移植时发生功能障碍的风险增加。 在之前的资助期间，我们的研究结果表明，特异性基质金属蛋白酶-9(MMP9) 抑制可显著改善正常肝脏的IRI，并揭示了基质金属蛋白酶-2和 TIMP-1在肝损伤中的作用本方案(I)探讨了抑制基质金属蛋白酶-9对小鼠肝脏的保护作用。 分析了基质金属蛋白酶-2和基质金属蛋白酶-1在肝脏缺血再灌注损伤中的作用。 正常和脂肪变性的肝脏。我们期望拟议的工作将提供关于以下方面的基本见解 关键MMPs/TIMPs的个体功能，导致新疗法的开发 可以最大限度地减少有害影响，同时最大限度地发挥其在 正常和脂肪变性的肝脏IRI。已建立的正常和脂肪变性部分肝IRI模型 小鼠，以及体外冷脂肪变性肝缺血后的大鼠同种移植将被用于 解决以下目标：(1)剖析基质金属蛋白酶-9特异性的机制 抑制作用影响边缘脂肪变性肝脏的IRI结果。利用基质金属蛋白酶-9/-缺陷小鼠和特异性 针对基质金属蛋白酶-9的治疗操作，我们将剖析特定的基质金属蛋白酶-9抑制是否(I)保护 I/R损伤引起的边缘脂肪变性肝脏，(Ii)扰乱白细胞运输和趋化因子释放/激活，以及 我们将(Iii)确定导致脂肪变性肝脏IRI中基质金属蛋白酶-9表达的细胞内信号机制；(2) 基质金属蛋白酶-2活性对正常人IRI预后影响的机制分析 还有脂肪变性的肝脏。我们将确定选择性的基质金属蛋白酶-2抑制(I)是否影响肝脏 功能/保存，(Ii)导致基质金属蛋白酶-9表达改变，(Iii)干扰白细胞模式 迁移和细胞因子/趋化因子的激活，此外，我们将(Iv)确定基质金属蛋白酶的来源- 2及其在正常和脂肪变性肝脏IRI中的相对贡献；以及(3)通过 哪种金属蛋白酶组织抑制物-1影响正常和脂肪变性肝脏的IRI。我们会 通过测定TIMP-1的影响评估TIMP-1在正常和脂肪变性肝IRI中的作用 缺乏(I)肝功能/保存，(Ii)肝再生和细胞凋亡，(Iii)基质金属蛋白酶激活，以及 关于(Iii)白细胞募集和促炎网络。此外，我们还将评估 TIMP-1过度表达可作为部分肝IRI和脂肪变性原位肝移植的治疗方法。

Hepatic ischemia reperfusion injury (IRI) occurs in all transplanted livers, in trauma, shock, and in elective surgery where blood supply to the liver is temporary interrupted. IRI causes up to 10% of early transplant failures and can lead to significantly higher incidence of acute and chronic rejections. Thousands of patients die every year while waiting for a donor organ. This gloomy scenario, together with the significant prevalence of obesity in the population, has led to an increased need of using suboptimal steatotic livers in transplantation at elevated risks of dysfunction based on their high susceptibility to IRI. In the previous funding period, our results demonstrated that specific matrix metalloproteinase-9 (MMP-9) inhibition profoundly ameliorates IRI in normal livers, and unveiled potential key roles for MMP-2 and TIMP-1 in liver injury. This proposal (i) explores the hepatoprotective properties of MMP-9 inhibition in marginal steatotic liver IRI and (ii) dissects the functions of MMP-2 and TIMP-1 in IR-induced damage in both normal and steatotic livers. We expect that the proposed work will provide fundamental insights on the individual functions of key MMPs/TIMPs, leading to the development of novel therapeutic manipulations that can minimize their detrimental effects while maximizing their beneficial functions in normal and in steatotic liver IRI. Well-established models of partial liver IRI in normal and in steatotic mice, and of ex vivo cold steatotic liver ischemia followed by iso-transplantation in rats will be used to address the following aims: (1) To dissect mechanisms by which Matrix Metalloproteinase-9 specific inhibition affects the IRI outcome in marginal steatotic livers. Using MMP-9-/- deficient mice and specific therapeutic manipulations against MMP-9, we will dissect whether specific MMP-9 inhibition (i) protects marginal steatotic livers from the I/R insult, (ii) disrupts leukocyte traffic and chemokine release/activation, and we will (iii) identify intracellular signaling mechanisms leading to MMP-9 expression in steatotic hepatic IRI; (2) To analyze mechanisms by which Matrix Metalloproteinase-2 activity affects the IRI outcome in normal and in steatotic livers. We will determine whether selective MMP-2 inhibition (i) affects liver function/preservation, (ii) results in altered expression of MMP-9, (iii) interferes with patterns of leukocyte migration and of cytokine/chemokine activation and, furthermore, we will (iv) identify the sources of MMP- 2 and their relative contribution in normal and steatotic liver IRI; and (3) To dissect the mechanisms by which tissue inhibitor of metalloproteinases-1 affects IRI in normal and in steatotic livers. We will assess the function of TIMP-1 in normal and in steatotic liver IRI by determining the impact of TIMP-1 deficiency on (i) liver function/preservation, (ii) liver regeneration and apoptosis, (iii) MMP activation, and on (iii) leukocyte recruitment and pro-inflammatory networks. Moreover, we will assess the function of Timp-1 overexpression as a therapeutic approach in partial liver IRI and in steatotic OLT.