Peripherally Active CB1 Receptor Antagonists for Alcohol-Induced Liver Fibrosis

描述（由申请方提供）：肝硬化以进行性肝纤维化为特征，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）在这一过程中至关重要。导致纤维化的中心事件是HSC从静止的富含维生素A的细胞类型活化和转变为缺乏维生素A的增殖性纤维化肌成纤维细胞。最近的证据表明，大麻素受体（简称CBR）对这一过程很重要。虽然CB 1 R和CB 2 R在正常肝脏中少量表达，但它们在纤维化肝脏中经历显著上调，主要在纤维化隔膜内的平滑肌α-肌动蛋白表达细胞中。有趣的是，CB 1 R在活化时是促纤维化的，而CB 2 R起抗纤维化作用。因此，拮抗CB 1 R是抑制HSC活化和纤维化进展的合理方法。因此，由国家酒精滥用和酒精中毒研究所（NIAAA）赞助的一项研究选择性CB 1 R拮抗剂SR 141716在酒精中毒中疗效的临床试验正在进行中。不幸的是，长期使用该药物可能对患者产生不良反应，特别是由于SR 141716在中枢神经系统（简称CNS）中的活性。因此，一种有效的策略，以CB 1 R为目标，可以绕过一些或大部分这些问题是开发外周活性CB 1 R拮抗剂，不能穿过血脑屏障（简称BBB）。这种策略将限制CB 1 R拮抗作用对外周的影响，从而消除慢性抑制中枢CB 1 R的CNS相关问题，同时保留这些化合物的有益抗纤维化潜力。因此，我们建议通过以下两个具体目标合成和测试外周活性CB 1 R拮抗剂。通过目标1，将合成带有季铵或氨基酸部分的SR 141716带电类似物，并检测其对CB 1 R的拮抗作用。该方法基于以下基本原理：与它们的中性亲脂性类似物（即，SR 141716），通常可以通过简单扩散穿透BBB。通过目标2，将通过三个子目标对这些化合物进行表征。(a)将使用功能性体外试验检测化合物的CB 1 R拮抗作用。(b)将在BBB转运的体外预测模型中研究这些化合物穿过BBB的能力。(c)将使用放射性配体竞争结合试验测定这些化合物对CB 1 R相对于CB 2 R的选择性。总之，这些研究旨在合成和测试SR 141716类似物作为外周活性CB 1 R拮抗剂的效用，这可能是酒精诱导的肝纤维化治疗药物开发的早期线索。

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.