POSTTRAUMATIC SEPSIS--REGULATION OF LPS-BINDING PROTEIN

革兰氏（-）脓毒症仍然是发病率和死亡率的主要原因 创伤后。 我们假设革兰氏（-）脓毒症开始时， 脂多糖（LPS）与肝细胞合成的蛋白质结合 称为LPS结合蛋白（LBP）。 我们还建议， LBP-LPS复合物与巨噬细胞上的受体结合， 在受体类型上，复合物要么激活巨噬细胞， 分泌细胞因子（CD 14受体）或促进摄取， LPS（乙酰化LDL受体）的降解。 自从肝脏库普弗 已知细胞是循环LPS的主要场所 摄取，我们认为肝细胞释放的LBP促进摄取 邻近的枯否细胞分泌LPS。 很可能细胞因子 Kupffer细胞释放的LBP进一步上调肝细胞LBP 合成创建一个重要的反馈回路和功能的LBP在 肝脏 目的一：确定细胞外和细胞内 肝细胞内脂多糖结合蛋白的调节。 我们将开始 定义外部信号（例如，细胞因子、糖皮质激素等） 其在体外调节肝细胞LBP的合成。 我们预测LBP 将以类似的方式对几个描述良好的急性期作出反应， 反应物 接下来，我们将确定枯否细胞在 在体外和体内提供这些信号。 除了我们 研究细胞外信号，我们将研究细胞内 LBP调节机制。 我们将确定LBP的合成是否 是受转录调控的 如果是这样，我们将分离LBP基因 启动子，这将使我们能够详细研究和比较LBP 与其他上调的分泌性肝细胞蛋白的调节 脓毒症（急性期反应物）。 目的二：确定 内毒素结合蛋白在内毒素与CD 14相互作用中的作用及对CD 14的影响 肝细胞上的乙酰化LDL受体。 为了研究LBP在 处理LPS的肝脏，我们首先需要检查 LPS-LBP复合物受体的表达。 所以我们会 确定肝细胞上CD 14和乙酰化LDL受体的表达 无论是在静止状态下还是在败血症和炎症条件下。 如果受体表达在体内受到调节，我们将研究 LBP和其他肝细胞衍生因子在此调节。 最后， 我们将确定LBP在这些受体摄取LPS中的作用， 在孤立的枯否细胞和整个器官中。 康贝特人将以 LBP-LPS结合的功能性后果（活化vs无活化） 到枯否细胞 在我们的研究完成后，我们将有 表征了LBP合成的调节和LBP的功能作用。 LBP在肝脏内LPS清除中的作用。 这些信息将提供 对宿主-LPS相互作用机制的重要见解， 诱导脓毒症反应。

Gram (-) sepsis remains a major cause of morbidity and mortality following trauma. We hypothesize that gram (-)sepsis is initiated when lipopolysaccharide (LPS) is bound by a protein synthesized by hepatocytes known as LPS binding protein (LBP). We also propose that the resultant LBP-LPS complex binds to receptors on macrophages which then, depending on the receptor type, the complex either activates the macrophage to secrete cytokines (CD14 receptor) or facilitates the uptake and degradation of LPS (acetylated-LDL receptor). Since the liver Kupffer cells are already known to be the principal site of circulating LPS uptake, we propose that LBP released by hepatocytes promote the uptake of LPS by the adjacent Kupffer cell. It is likely that cytokines released by the Kupffer cells then further upregulates hepatocyte LBP synthesis creating an important feedback loop and function of LBP in the liver. AIM I: TO DETERMINE THE EXTRACELLULAR AND INTRACELLULAR REGULATION OF LPS BINDING PROTEIN IN HEPATOCYTES. We will begin by defining the external signals (e.g., cytokines, glucocorticoids, etc.) which regulate hepatocyte LBP synthesis in vitro. We predict that LBP will respond in a similar manner to several well-described acute phase reactants. Next, we will determine the role of Kupffer cells in providing these signals both in vitro and in vivo. In addition to our studies on the extracellular signals, we will study the intracellular mechanisms of LBP regulation. We will determine if the synthesis of LBP is transcriptionally regulated. If so, we will isolate the LBP gene promoter, which will allow us to study and compare, in detail, LBP regulation with other secreted hepatocyte proteins that are upregulated in sepsis (acute phase reactants). AIM II: TO DETERMINE THE FUNCTIONAL ROLE OF LPS BINDING PROTEIN IN THE INTERACTION OF LPS WITH CD14 AND THE ACETYLATED-LDL RECEPTOR ON LIVER CELLS. To study the role of LBP in the processing of LPS by the liver, we will first need to examine the expression of the receptors for LPS-LBP complexes. Therefore, we will define the expression of CD14 and acetylated-LDL receptors on liver cells both in the resting state and under septic and inflammatory conditions. If receptor expression is regulated in vivo, we will study the role of LBP and other hepatocyte-derived factors in this regulation. Finally, we will determine the role of LBP in the uptake of LPS by these receptors in isolated Kupffer cells and the whole organ. We will determine the functional consequence (activation vs no activation) of LBP-LPS binding to Kupffer cells. At the completion of our studies we will have characterized the regulation of LBP synthesis and the functional role of LBP in LPS clearance within the liver. This information will provide important insights into the mechanisms of host-LPS interaction and the induction of the septic response.