Age Effects on Liver Inflammation and Injury

描述（由申请人提供）：肝损伤是儿童和成人患者肝功能障碍的主要原因。我们使用已建立的小鼠肝脏I/R模型进行的初步研究表明，成熟小鼠（12-13月龄）在I/R后的肝损伤明显大于年轻小鼠（6-8周龄）。这些发现与创伤患者的临床研究一致，表明儿科患者的多器官功能障碍综合征发生率远低于成人患者。本研究的长期目标是确定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将验证成熟小鼠肝细胞中转录因子NF-KB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，在成熟小鼠的全肝中，NF-KappaB的活化降低，但促炎细胞因子的产生没有改变，这表明NF-KappaB的库普弗细胞活化不会随着年龄的增长而改变。目的2将验证成熟小鼠肝脏HSP70表达降低导致氧化组织损伤和肝细胞死亡增加，从而增强I/R损伤的假设。我们提供的证据表明，成熟小鼠肝脏中HSP70蛋白表达降低，这与坏死和凋亡机制的肝细胞损伤增加有关。目的3将验证CD4淋巴细胞调节肝脏I/R损伤的假设，以及成熟小鼠CD4淋巴细胞功能改变导致肝损伤增强的假设。我们的初步数据表明，cd4敲除小鼠在I/R后的肝损伤增加，其模式与在成熟小鼠中观察到的相同。我们还发现，在年轻小鼠和成熟小鼠之间，肝脏驻留淋巴细胞的表型存在显著差异。目的4将验证一个假设，即在年轻和成熟小鼠的肝细胞蛋白质组中存在许多细胞特异性改变，这些变化有助于这些年龄人群对I/R损伤的不同反应。我们将使用蛋白质组学来确定I/R前后Kupffer细胞、肝细胞、窦内皮细胞和肝驻留淋巴细胞的亚细胞蛋白质组，以确定年龄相关的改变。这些研究将促进我们对年龄依赖机制的理解，这些机制区分了成人和儿科患者群体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.