Creating a toolkit to measure in vivo bile acid transport

描述（由申请人提供）：肠道功能障碍可能损害BA摄取和反馈抑制肝胆汁酸（BA）合成，从而导致BA吸收不良（BAM）。增加的粪便ba促进结肠病理；霍乱性腹泻，可能有肿瘤。肠BA摄取主要由回肠顶端钠依赖性胆汁酸转运蛋白（ASBT; SLC10A2）介导。ASBT功能降低降低BA吸收；无灰小鼠粪便中ba增加。在原发性BAM中，肠成纤维细胞生长因子-19 （FGF19）的反馈抑制受损会增加BA合成，肠道BA水平超过BA转运能力。fgf15缺失小鼠模拟原发性BAM；他们也会增加粪便中的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，可抑制ASBT功能。如果药物在体内损害ASBT功能，改变BA运输可能导致意想不到的副作用，包括结肠病理。目前测量BA在体内运输和分布的工具是有限的。为了弥补这一局限性，我们设想了一种利用质子(1H)-氟（19F）联合磁共振成像（MRI）的活体动物创新方法；一种具有临床实践转化潜力的新方法。R21基金将支持一个具有独特资格的研究团队，该团队使用生化方法和活体动物MRI创建和测试（体外和体内）多氟、非放射性（19F） BA (MFBA): Raufman博士是BA对结肠上皮影响的专家；测量BA体外转运的专家Polli博士；道森博士是测量BA在体内运输的专家；余博士是开发19f成像示踪剂（19FIT）的专家化学家；以及小动物核磁共振专家徐博士。我们将设计、创建和测试两类19F标记的制剂：(1)通过ASBT结合和运输的MFBA[例如，带有三个19F原子/分子的19F标记的chenodeoxycholic acid (19F3-CDCA)]和(2)既不通过ASBT结合也不运输的非活性对照剂（例如19FIT）。为了实现这些目标，我们提出了两个具体目标：制备多氟BA并测试其体外稳定性和与肠内BA的相互作用

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.