Creating a toolkit to measure in vivo bile acid transport

描述（由申请方提供）：肠功能障碍可能损害BA摄取和肝胆汁酸（BA）合成的反馈抑制，从而导致BA吸收不良（BAM）。粪便BA增加促进结肠病理学;霍乱性腹泻和可能的肿瘤形成。肠BA摄取主要由回肠顶端钠依赖性胆汁酸转运蛋白（ASBT; SLC 10A 2）介导。ASBT功能降低会降低BA吸收; Asbt缺失小鼠的粪便BA增加。在原发性BAM中，肠成纤维细胞生长因子-19（FGF 19）的反馈抑制受损增加BA合成，并且肠BA水平压倒BA转运体能力。Fgf 15缺失小鼠模拟原发性BAM;它们也具有增加的粪便BA。我们最近发表的体外和计算机数据表明，常用药物，包括他汀类药物，抑制ASBT功能。如果药物在体内损害ASBT功能，则BA转运的改变可能导致意外的副作用，包括结肠病理。目前用于测量BA在体内转运和分布的工具是有限的。为了弥补这一局限性，我们设想了一种在活体动物中使用质子（1H）-氟（19 F）磁共振成像（MRI）的创新方法;这是一种具有临床实践转化潜力的新方法。R21基金将支持一个有资格创建和测试使用生物化学方法和活体动物MRI的（体外和体内）多氟化非放射性（19 F）BA（MFBA）：Raufman博士，BA对结肠上皮影响的专家; Polli博士，体外测量BA转运的专家; Dawson博士，体内测量BA转运的专家; Yu博士，开发19 F成像示踪剂（19 FIT）的专家化学家;和Xu博士，小动物MRI专家。我们将设计、创建和测试两类19 F标记试剂：（1）通过ASBT结合和转运的MFBA [例如，具有三个19 F原子/分子的19 F标记鹅去氧胆酸（19 F3-CDCA）]和（2）既不通过ASBT结合也不转运的无活性对照试剂（例如，19 FIT）。为了实现这些目标，我们提出了两个具体目标：> 1。制备多氟化BA并测试体外稳定性和与肠溶BA的相互作用 运输机> 2.测试WT中多氟化BA的体内稳定性和转运，Slc 10a 2- /- 和Fgf 15-/-小鼠的研究。我们的多学科团队包括在测量胆汁酸转运方面具有毋庸置疑的专业知识的研究人员。该团队是唯一有资格开发这项创新技术的基础上，磁共振成像的新创建的非放射性，氟标记的胆汁酸，可用于获得时间和空间信息的胆汁酸运输活动物和人类。 公共卫生相关性：除了它们作为促进脂肪吸收的去污剂的传统作用外，胆汁酸是影响多个器官的有效信号分子;它们调节肠道运动和激素产生、结肠生理学和癌症易感性，并改变血管张力、葡萄糖代谢、脂质代谢和能量利用。为了了解胆汁酸的这些复杂作用，需要新技术，允许同时监测胃肠道和代谢组织中的胆汁酸水平。在这项R21申请中，我们提出开发一种基于新创建的非放射性氟标记胆汁酸的磁共振成像的创新技术，该技术可用于获得活体动物和人类的时间和空间信息。

DESCRIPTION (provided by applicant): Intestinal dysfunction may impair BA uptake and feedback inhibition of hepatic bile acid (BA) synthesis, thereby resulting in BA malabsorption (BAM). Increased fecal BAs promote colon pathology; cholerrheic diarrhea and possibly neoplasia. Intestinal BA uptake is mediated primarily by the ileal Apical Sodium-dependent Bile Acid Transporter (ASBT; SLC10A2). Reduced ASBT function decreases BA absorption; Asbt-null mice have increased fecal BAs. In primary BAM impaired feedback inhibition by intestinal fibroblast growth factor-19 (FGF19) increases BA synthesis and intestinal BA levels overwhelm BA transporter capacity. Fgf15-null mice mimic primary BAM; they also have increased fecal BAs. Our recently published in vitro and in silico data indicate that commonly-used drugs, including statins, inhibit ASBT function. If drugs impair ASBT function in vivo, altered BA transport may result in unanticipated side-effects, including colon pathology. Current tools to measure BA transport and distribution in vivo are limited. To remedy this limitation, we conceived an innovative approach in live animals that utilizes combined proton (1H)-fluorine (19F) magnetic resonance imaging (MRI); a novel methodology with translational potential for clinical practice. R21 funding will support a research team uniquely qualified to create and test (in vitro and in vivo) multi-fluorinated, non-radioactive (19F) BAs (MFBA) using biochemical methods and live animal MRI: Dr. Raufman, an expert in BA effects on colon epithelium; Dr. Polli, an expert in measuring BA transport in vitro; Dr. Dawson, an expert in measuring BA transport in vivo; Dr. Yu, an expert chemist who developed 19F-imaging tracer (19FIT); and Dr. Xu, an expert in small animal MRI. We will design, create and test two classes of 19F-labeled agents: (1) MFBA that are bound and transported by ASBT [e.g. 19F-labeled chenodeoxycholic acid (19F3-CDCA) with three 19F atoms/molecule] and (2) Inactive control agents neither bound nor transported by ASBT (e.g. 19FIT). To accomplish these goals, we propose two Specific Aims: > 1. Create multi-fluorinated BAs and test in vitro stability and interaction with enteric BA transporters. > 2. Test in vivo stability and transport of multi-fluorinated BAs in WT, Slc10a2- /- and Fgf15-/- mice using biochemical methods and live-animal magnetic resonance imaging. Our multidisciplinary team includes established investigators with unquestioned expertise in measuring bile acid transport. This team is uniquely qualified to develop this innovative technology based on magnetic resonance imaging of newly-created non-radioactive, fluorine-labeled bile acids that can be used to obtain both temporal and spatial information on bile acid transport in live animals and humans. PUBLIC HEALTH RELEVANCE: In addition to their traditional role as detergents that facilitate fat absorption, bile acids are potent signaling molecules that affect multiple organs; they modulate gut motility and hormone production, colon physiology and cancer susceptibility, and alter vascular tone, glucose metabolism, lipid metabolism and energy utilization. To understand these complex actions of bile acids new technology is required that permits simultaneous monitoring of bile acid levels in the gastrointestinal tract and metabolic tissues. In this R21 application, we propose to develop an innovative technology based on magnetic resonance imaging of newly-created non- radioactive fluorine-labeled bile acids that can be used to obtain both temporal and spatial information in live animals and humans.