Hepatic drug metabolism in inflammation

描述（由申请人提供）： 在感染或炎症期间，许多关键药物代谢酶（DME）的表达在肝脏中被抑制，导致药物的代谢和清除改变。这增加了对肝脏药物不良反应的易感性，从而使临床重要药物无效甚至有毒。DME的基因表达受核受体（NR）超家族成员的调控。然而，肝脏DME在炎症过程中受到抑制的确切机制尚未完全了解。肝脏中的炎症反应由枯否细胞（KC）上存在的Toll样受体（TLR）介导，其识别来自受损或应激细胞的微生物组分和内源性配体。这导致细胞因子的诱导，导致肝细胞中基因表达的抑制。然而，TLR也存在于肝细胞上，并且有证据表明肝细胞可以被来自革兰氏阴性菌的脂多糖（LPS）直接靶向，导致细胞色素P450基因表达的抑制。总体假设是肝细胞中TLR信号通路的激活通过靶向NR功能从而损害DME表达和活性来改变感染和炎症期间的肝脏药物代谢。为了研究这一假设，提出了以下具体目标。具体目标1：确定细胞表面受体TLR2和TLR4以及关键衔接蛋白（TIRAP，TRIP）是否参与体内DME和NR的调节。具体目标2：确定肝细胞中的TLR信号传导是否直接参与DME的调节。探索TLR在体外调节人DME中的作用。具体目标3：检查TLR的激活是否会改变药物的代谢和毒性，免疫抑制剂，环孢素A，和抗肿瘤药，氯丙嗪。这些实验产生的数据将成为分子药理学独立研究项目的基础。PI将由Dr. B指导。Moorthy和H博士Strobel，他们是药理学方面的知名研究者。丰富的知识环境和广泛的资源可用于完成这项工作。 了解TLR信号在药物代谢调节中的作用将为未来的实验操作确定新的靶点，以防止炎症介导的药物生物转化改变。最后，这些研究将为新药临床试验中TLR基因多态性个体的筛选提供依据。

DESCRIPTION (provided by applicant): During infection or inflammation, the expression of many key drug metabolizing enzymes (DMEs) is suppressed in the liver, leading to altered metabolism and clearance of drugs. This increases the susceptibility to adverse hepatic drug reactions, thus rendering clinically-important medications ineffective or even toxic. The gene expression of DMEs is regulated by members of the nuclear receptor (NR) superfamily. However, the exact mechanism by which hepatic DMEs are suppressed during inflammation is not fully understood. Inflammatory responses in the liver are mediated by Toll-like receptors (TLRs) present on Kupffer cells (KCs) which recognize microbial components and endogenous ligands from damaged or stressed cells. This results in the induction of cytokines, leading to suppression of gene expression in hepatocytes. However, TLRs are also present on hepatocytes, and there is evidence that hepatocytes can be directly targeted by lipopolysaccharide (LPS) from gram negative bacteria resulting in suppression of Cytochrome P450 gene expression. The overall hypothesis is that activation of TLR signaling pathways in hepatocytes alters hepatic drug metabolism during infection and inflammation by targeting NR function and thereby impairing DME expression and activity. To investigate this hypothesis, the following Specific Aims are proposed. Specific Aim 1: Determine whether the cell surface receptors, TLR2 and TLR4 and the critical adaptor proteins (TIRAP, TRIP), are involved in regulation of DMEs and NRs in vivo. Specific Aim 2: Determine whether TLR signaling in the hepatocytes are directly involved in regulation of DMEs. Explore the role of TLRs in regulation of human DMEs in vitro. Specific Aim 3: Examine whether activation of TLRs will alter the metabolism and toxicity of the drugs, the immunosuppressant, Cyclosporin A, and the anti-depressant, Chlorpromazine. The data generated from these experiments will form the basis of an independent research program in Molecular Pharmacology. The PI will be mentored by Dr. B. Moorthy and Dr. H. Strobel, who are well-established investigators in Pharmacology. A rich intellectual environment and extensive resources are available for completion of this work. Understanding the role of TLR signaling in regulation of drug metabolism will identify novel targets for future experimental manipulations to prevent inflammation-mediated alterations in drug biotransformation. Finally, these studies will provide a basis for screening of individuals with polymorphisms in TLR genes during clinical trials of new drugs.