Peripherally Active CB1 Receptor Antagonists for Alcohol-Induced Liver Fibrosis

描述（由申请人提供）：以进行性肝纤维化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之一。肝星状细胞（简称hsc）在这一过程中起关键作用。导致纤维化的一个中心事件是造血干细胞从富含维生素A的静止细胞类型激活并转变为缺乏维生素A的增殖性成纤维性肌成纤维细胞。最近的证据表明大麻素受体（简称CBRs）对这一过程很重要。虽然CB1R和CB2R在正常肝脏中少量表达，但它们在肝硬化肝脏中显著上调，主要在纤维化隔内的平滑肌a-肌动蛋白表达细胞中上调。有趣的是，CB1R在激活时具有促纤维化作用，而CB2R则具有抗纤维化作用。因此，拮抗CB1R是抑制HSC活化和纤维化进展的合理途径。因此，由国家酒精滥用和酒精中毒研究所（NIAAA）赞助的一项临床试验正在进行中，研究选择性CB1R拮抗剂SR141716对酒精中毒的疗效。不幸的是，长期使用这种药物可能会对患者产生不良反应，特别是由于SR141716在中枢神经系统（简称CNS）中的活性。因此，针对CB1R的有效策略是开发不能穿过血脑屏障（简称BBB）的外周活性CB1R拮抗剂。该策略将限制CB1R拮抗剂对外周的作用，从而消除慢性抑制中枢CB1R的cns相关担忧，同时保留这些化合物有益的抗纤维化潜力。因此，我们建议通过以下两个特定目的来合成和测试外周活性CB1R拮抗剂。通过目的1，将合成带有季铵或氨基酸片段的SR141716带电类似物，并测试其对CB1Rs的拮抗作用。这种方法是基于带电化合物不会穿过血脑屏障的基本原理，除非通过特定的转运体运输，与它们的中性亲脂类似物（即SR141716）相反，它们通常可以通过简单的扩散穿透血脑屏障。通过目标2，这些化合物的表征将通过三个子目标进行。(a)将使用功能性体外试验测试化合物的CB1R拮抗作用。(b)这些化合物穿过血脑屏障的能力将在血脑屏障运输的体外预测模型中进行研究。(c)使用放射性配体竞争结合试验确定这些化合物对CB1R比CB2R的选择性。总的来说，这些研究旨在合成和测试SR141716类似物作为外周活性CB1R拮抗剂的效用，这可能作为酒精性肝纤维化治疗方法开发的早期线索。

DESCRIPTION (provided by applicant): Hepatic cirrhosis characterized by progressive liver fibrosis is one of the leading causes of morbidity from chronic abuse of ethanol worldwide. Hepatic stellate cells (abbreviated HSCs) are critical to this process. A central event leading up to fibrosis is the activation and transition of HSCs from a quiescent vitamin A-rich cell type to a vitamin A-deficient, proliferative, fibrogenic myofibroblast. Recent evidence suggests that cannabinoid receptors (abbreviated CBRs) are important to this process. While CB1R and CB2R are marginally expressed in normal liver, they undergo marked upregulation in the cirrhotic liver, predominantly in smooth muscle a-actin expressing cells within the fibrotic septa. Interestingly, CB1R is pro-fibrotic upon activation, whereas CB2R plays an anti-fibrotic role. Therefore, antagonism of CB1R is a rational approach to inhibit HSC activation and progression of fibrosis. Accordingly, a clinical trial examining the efficacy of the selective CB1R antagonist SR141716 in alcoholism sponsored by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) is underway. Unfortunately, chronic use of this medication may have undesirable adverse effects in patients particularly due to the activity of SR141716 in the central nervous system (abbreviated CNS). Thus, an effective strategy to target the CB1R that could by-pass some or most of these concerns is to develop peripherally active CB1R antagonists that cannot cross the blood-brain barrier (abbreviated BBB). This strategy would restrict the effect of CB1R antagonism to the periphery, and thereby eliminate the CNS-related concerns of chronically inhibiting central CB1R while retaining the beneficial antifibrotic potential of these compounds. Thus, we propose to synthesize and test peripherally active CB1R antagonists through the following two specific aims. Through aim 1, charged analogs of SR141716 bearing either a quaternary ammonium or an amino acid moiety will be synthesized and tested for antagonism of CB1Rs. This approach is based on the rationale that charged compounds do not cross the BBB, unless transported by specific transporters, in contrast to their neutral lipophilic analogs (i.e., SR141716) that can often penetrate the BBB by simple diffusion. Through aim 2, characterization of these compounds will be performed via three sub-aims. (a) The compounds will be tested for CB1R antagonism using a functional in vitro assay. (b) The ability of these compounds to cross the BBB will be studied in an in vitro predictive model of BBB transport. (c) The selectivity of these compounds for CB1R over CB2R using radioligand competition binding assays will be determined. In total, these studies are designed to synthesize and test the utility of SR141716 analogs as peripherally active CB1R antagonists, which may serve as early leads for therapeutics development for alcohol-induced liver fibrosis.