Hepatic drug metabolism in inflammation

描述(由申请人提供)： 在感染或炎症期间，许多关键的药物代谢酶(DME)在肝脏中的表达受到抑制，导致新陈代谢和药物清除的改变。这增加了对肝脏药物不良反应的易感性，从而使临床上重要的药物无效甚至有毒。DMES的基因表达受核受体超家族成员的调控。然而，肝脏DME在炎症过程中被抑制的确切机制尚不完全清楚。肝脏的炎症反应是由库普弗细胞(KCs)上的Toll样受体(TLRs)介导的，KCs识别受损或应激细胞中的微生物成分和内源性配体。这会导致细胞因子的诱导，导致肝细胞中基因表达的抑制。然而，肝细胞上也存在TLRs，有证据表明，革兰氏阴性菌的脂多糖(LPS)可以直接靶向肝细胞，从而抑制细胞色素P450基因的表达。总的假设是，肝细胞中TLR信号通路的激活通过靶向NR功能从而损害DME的表达和活性来改变感染和炎症过程中的肝脏药物代谢。为了研究这一假设，提出了以下具体目标。具体目的1：确定细胞表面受体TLR2和TLR4以及关键适配蛋白(TIRAP，TRIP)是否参与体内DMES和NRS的调节。具体目标2：确定肝细胞中的TLR信号是否直接参与DMES的调节。探讨TLRs在体外调节人DMES中的作用。具体目标3：检查TLRs的激活是否会改变药物、免疫抑制剂环孢素A和抗抑郁剂氯丙嗪的代谢和毒性。这些实验产生的数据将构成分子药理学独立研究计划的基础。PI将由B.Moorthy博士和H.Strobel博士指导，他们都是药理学方面的知名研究人员。完成这项工作有丰富的智力环境和广泛的资源。 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，以防止药物生物转化中的炎症介导的改变。最后，这些研究将为在新药临床试验期间筛选TLR基因多态的个体提供基础。

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.