Peripherally Selective CB1 Receptor Antagonists for Alcoholic Liver Disease

描述（由申请人提供）：以进行性肝病为特征的肝硬化是世界范围内慢性滥用乙醇导致发病的主要原因。此外，肝纤维化也与肝细胞癌的发病率增加有关，而肝细胞癌通常是致命的。目前还没有批准治疗酒精性肝纤维化的药物。内源性大麻素受体（CBRs），特别是CB1R，最近成为治疗肝纤维化和其他相关疾病的临床前验证靶点。CB1R和CB2R均在中枢神经系统（CNS）中表达。它们也存在于包括肝脏在内的各种组织中。CB1R和CB2R在肝脏疾病的进展中起相互作用。虽然CB1R和CB2R在正常肝脏中少量表达，但在肝损伤或酒精性肝病发生时，它们在肝细胞和肝星状细胞（HSC）中显著上调。过去的研究也表明，CB1R拮抗剂有希望进一步开发和测试治疗酒精性肝病。目前可用的CB1R拮抗剂由于其对中枢神经系统的有害作用而不适合用于肝纤维化。例如，由赛诺菲-安万特公司开发的CB1R选择性拮抗剂SR141716（利莫那班(c)）对肥胖患者产生了不良的中枢神经系统相关副作用，包括抑郁和自杀念头。这在大量患有抑郁症的酗酒者中是一个特别值得关注的问题。这些副作用导致FDA拒绝在美国使用这种化合物，并在批准后从欧洲撤回。尽管存在这些局限性，来自肥胖利莫那班（里约热内卢）试验和后续研究的数据表明，除了与中枢神经系统相关的作用外，SR141716总体上耐受性良好，并且具有一些与中枢神经系统无关的阳性特性，如改善血脂水平和胰岛素敏感性。这些结果还表明，针对酒精性肝病和其他相关病因的CB1R的有效策略是开发不能渗透血脑屏障（BBB）的外周限制性CB1R拮抗剂，从而绕过慢性拮抗该受体的中枢神经系统相关问题，这是本研究项目的总体目标。通过niaaa资助的小型研究基金（R03AA017514），我们已经确定了基于核心SR141716结构的CB1R拮抗剂，该拮抗剂降低了血脑屏障的渗透性。利用这些在CB1R上具有药理相关活性的早期化合物作为模板，通过合理的药物设计进一步改进，我们希望开发和测试下一代化合物，作为药物开发的先导，通过以下具体目标治疗酒精性肝纤维化：通过目标1，我们建议合成SR141716的其他类似物，其结构特性旨在限制其在血脑屏障上的运输。通过目的2，我们建议用体外功能测定来表征这些合成化合物。此外，我们还将研究一些活性化合物在啮齿动物体内的药代动力学特性，包括血脑屏障通透性和半衰期。此外，我们建议进行基因表达谱实验，比较和对比我们的最佳引物SR141716在稳定表达CB1R的肝星状细胞系中的全基因组效应。通过aim 3，我们建议在酒精性脂肪变性的啮齿动物体内Lieber-DeCarli模型中对我们的最佳化合物进行功效测试。我们将评估ALD的几种生物标志物，以监测测试化合物在酒精性肝病模型中的疗效。

DESCRIPTION (provided by applicant): Cirrhosis characterized by progressive liver disease is a leading cause of morbidity from chronic abuse of ethanol worldwide. In addition, hepatic fibrosis is also associated with increased rates of hepatocellular carcinoma, which is usually fatal. There is currently no approved drug to treat alcoholic liver fibrosis. The endocannabinoid receptors (CBRs), particularly CB1R, have recently emerged as pre-clinically validated targets to treat liver fibrosis and other related disorders. Both CB1R and CB2R are expressed in the central nervous system (CNS). They also exist peripherally in a variety of tissues including the liver. CB1R and CB2R play reciprocal roles in progression of liver disease. While CB1R and CB2R are marginally expressed in normal liver, they undergo marked upregulation upon liver injury or onset of alcoholic liver disease in hepatocytes and hepatic stellate cells (HSC). Past studies also indicate that antagonists of CB1R are promising candidates for further development and testing to treat alcoholic liver disease. Currently available CB1R antagonists are unsuitable for use in liver fibrosis due to their deleterious effects on the CNS. For example, the selective CB1R antagonist SR141716 (Rimonabant(c)), which was developed by Sanofi-Aventis for obesity, produced undesirable CNS-related side effects in patients including depression and suicidal ideation. This is a particular concern in a large population of alcoholics who suffer from depression. These side effects led the FDA to reject this compound for use in the US and it was withdrawn from Europe post-approval. In spite of these limitations, data from the Rimonabant for Obesity (RIO) trial and follow-up studies indicate that CNS related effects aside, SR141716 is well tolerated in general and has several positive non-CNS related properties, such as improved blood lipid profile, and insulin sensitivity in users. These results also indicate that an effective strategy to target CB1R in alcoholic liver disease and other related etiologies that would by-pass the CNS-related concerns of chronically antagonizing this receptor is to develop peripherally restricted CB1R antagonists that cannot permeate the blood-brain barrier (BBB), which is the overall goal of this research project. Through our ongoing NIAAA-funded small research grant (R03AA017514), we have identified CB1R antagonists based upon the core SR141716 structure that have reduced permeability across the BBB. Using these early compounds with pharmacologically relevant activity at CB1R as templates for further refinement through rational drug design, we expect to develop and test the next generation of compounds to serve as leads for medications development to treat alcoholic liver fibrosis through the following specific aims: Through aim 1 we propose to synthesize additional analogs of SR141716 with structural properties designed to limit their transport across the BBB. Through aim 2, we propose to characterize these synthesized compounds using functional in vitro assays. Further, we will also study pharmacokinetic properties of a select number of active compounds in rodents including BBB permeability and half-life. Additionally, we propose to conduct gene expression profiling experiments to compare and contrast the genome-wide effects of our best lead to SR141716 in a hepatic stellate cell-line stably expressing CB1R. Through aim 3, we propose to conduct efficacy testing of our best compound in an in vivo Lieber-DeCarli rodent model of alcoholic steatosis. We will evaluate several biomarkers of ALD to monitor efficacy of the test compound in this well-established model of alcoholic liver disease. PUBLIC HEALTH RELEVANCE: Project Narrative Alcoholic liver disease has a high mortality rate and increases the chance of developing liver cancer. There are no FDA-approved drugs available currently to treat this disease. Our goal is to develop drugs to treat alcoholic liver disease by targeting a particular type of protein called the type 1 cannabinoid receptor that has been implicated as a target for this disorder. Using medicinal chemistry and pharmacology, we propose to synthesize and test compounds that inhibit the function of type 1 cannabinoid receptors.