Age Effects on Liver Inflammation and Injury

描述(由申请人提供)：肝脏损伤是导致儿童和成人患者肝功能障碍的主要原因。我们利用已建立的小鼠肝脏I/R模型进行的初步研究表明，成年小鼠(12-13个月龄)在I/R后的肝脏损伤明显大于幼鼠(6-8周龄)。这些发现与对创伤患者的临床研究一致，这些研究表明，儿童患者的多器官功能障碍综合征的发生率远远低于成人患者。这项建议的长期目标是确定区分年轻和成熟小鼠对肝脏I/R反应的分子和细胞机制。目的1将测试转录因子NF-KB在成熟小鼠的肝细胞中被选择性抑制，导致细胞死亡和器官损伤增加的假设。我们发现，成熟小鼠全肝组织中的NF-kappaB活性降低，但促炎细胞因子的产生没有改变，这表明Kupffer细胞的激活没有随着年龄的增长而改变。目的2验证成熟小鼠肝脏HSP70表达减少导致氧化组织损伤增加和肝细胞死亡导致I/R损伤加重的假说。我们提供的证据表明，HSP70蛋白在成熟小鼠的肝脏中的表达减少，这与坏死和凋亡机制下的肝细胞损伤增加有关。目的3将验证一种假设，即CD4淋巴细胞调节肝脏I/R损伤，而在成熟小鼠中，CD4淋巴细胞功能改变有助于加重肝脏损伤。我们的初步数据表明，CD4基因敲除小鼠在I/R后增加了肝脏损伤，其模式与在成熟小鼠中观察到的模式相同。我们还发现幼年鼠和成年鼠肝内淋巴细胞的表型有显著差异。目的4将验证一种假设，即在幼年和成熟小鼠之间，肝细胞的蛋白质组中存在许多细胞特异性的变化，这些变化导致了这些年龄段的小鼠对I/R损伤的不同反应。我们将使用蛋白质组学的方法来检测I/R前后Kupffer细胞、肝细胞、肝窦内皮细胞和肝内淋巴细胞的亚细胞蛋白质组，以确定与年龄相关的改变。这些研究将促进我们对年龄相关机制的理解，这些机制区分成人和儿童患者对急性肝损伤的肝脏炎症反应。

DESCRIPTION (provided by the applicant): Hepatic injury is a primary cause of liver dysfunction in both pediatric and adult patients. Our preliminary studies using an established model of murine hepatic I/R indicate that mature mice (12-13 months of age) have significantly greater liver injury after I/R than do young mice (6-8 weeks of age). These findings are consistent with clinical studies of trauma patients which suggest that pediatric patients have a far lower incidence of multiple organ dysfunction syndrome than do adult patients. The long-term goal of this proposal is to determine the molecular and cellular mechanisms that differentiate young and mature mice in their response to hepatic I/R. Aim 1 will test the hypothesis that the transcription factor, NF-KB, is selectively depressed in hepatocytes of mature mice, leading to increased cell death and organ injury. We show that NF-KappaB activation is decreased in whole livers from mature mice, but that proinflammatory cytokine production is unaltered, suggesting that Kupffer cell activation of NF-KappaB is unaltered with age. Aim 2 will test the hypothesis that reduced hepatic expression of HSP70 in mature mice leads to increased oxidative tissue injury and hepatocyte cell death contributing to augmented I/R injury. We provide evidence that HSP70 protein expression is reduced in livers from mature mice and that this is associated with increased hepatocellular injury of both necrotic and apoptotic mechanisms. Aim 3 will test the hypothesis that CD4 lymphocytes serve to regulate hepatic I/R injury and that in mature mice altered function of CD4 lymphocytes contributes to augmented liver injury. Our preliminary data demonstrates that CD4-knockout mice have increased liver injury after I/R in a pattern that is identical to that observed in mature mice. We also show significant differences in the phenotypes of liver-resident lymphocytes between young and mature mice. Aim 4 will test the hypothesis that there are a number of cell-specific alterations in the proteomes of liver cells between young and mature mice and that these changes contribute to the divergent responses to I/R injury in these age populations. We will employ proteomics to determine the subcellular proteomes of Kupffer cells, hepatocytes, sinusoidal endothelial cells, and liver-resident lymphocytes before and after I/R to identify age-related alterations. These studies will advance our understanding of the age-dependent mechanisms that differentiate the hepatic inflammatory response of adult and pediatric patient populations to acute liver injury.