Connecting interpersonal variation in gut microbial communities to warfarin efficacy

 说明(申请人提供)：华法林(香豆素)，一种维生素K拮抗剂，是最常用的口服抗凝剂。它也是目前医疗实践中最不可预测和最危险的药物之一而臭名昭著。在最佳剂量下观察到的20倍范围可以部分归因于遗传和饮食：例如，与维生素K循环和华法林代谢相关的基因的多态，包括细胞色素P3A4，可以改变华法林的药代动力学和功能。此外，改变叶类蔬菜的摄入量可能会抵消这种药物的效果。叶醌是一种植物维生素K，富含叶醌。尽管对这些因素进行了广泛的研究，但观察到的华法林剂量变化的近一半仍然无法解释。值得注意的是，肝脏中维生素K的分子特征表明，只有10%是以植物为基础的形式：其余的带有细菌生物合成的化学特征。我们每个人胃肠道中独特的微生物群落(微生物区系)如何影响对华法林或其他药物的反应的变异性尚不清楚。这些挑战的解决方案可能导致更安全和更有效的华法林疗法。与人类基因组中的多态不同，肠道微生物群落可以快速修改，因此药物和患者(通过他们的微生物群)都可以调整，以获得最大的治疗效益。这项申请提出了一项计划，以确定决定华法林反应的特定微生物机制。我已经建立了一个系统来测量灵知生菌小鼠的华法林功能，这些小鼠的微生物区系可以被精确地操纵。我发现，缺乏肠道微生物的小鼠对华法林表现出严重的高反应性，这与微生物区系衍生的维生素K在这一过程中的作用是一致的。然而，我也发现药物代谢酶(Dme)的调节发生了变化，包括人类CYP3a4(Cyp3a11)的小鼠同源物。具有完整肠道微生物群落的无菌小鼠的定居可使华法林功能和DME表达正常化。在目标1中，这个系统将被用来确定微生物来源的维生素K中的人际差异对华法林功能的影响。在目标2中，我将定义肠道微生物对宿主DME基因表达的调节如何影响华法林的代谢和功能。这些目标的成功实现将解决关键问题，以解释一种广泛使用的药物的频繁和危险的不良反应。这样的理解可以为优化华法林剂量或肠道群落组成的新方法打开大门，以实现更安全的药理学。此外，这些研究将突出宿主-微生物区系的相互作用，这些相互作用可能会影响其他维生素K依赖过程和药物的功能。

 DESCRIPTION (provided by applicant): Warfarin (Coumadin), a vitamin K antagonist, is the most commonly prescribed oral anticoagulant. It is also notorious as one of the most unpredictable and dangerous drugs in current medical practice. The observed 20- fold range in optimal dose can be partially attributed to genetics and diet: for example, polymorphisms in genes linked to vitamin K recycling and warfarin metabolism, including CYP3A4, can change warfarin pharmacokinetics and function. Also, altered intake of leafy vegetables rich in phylloquinone, the plant-based form of vitamin K, can override the effects of the drug. Despite extensive studies with respect to these factors, nearly half of observed warfarin dose variation still remains unexplained. Notably, molecular characterization of vitamin K in the liver reveals that only 10% is the plant-based form: the remainder carries the chemical signature of bacterial biosynthesis. How the unique microbial communities (microbiota) that each of us harbors in the gastrointestinal tract influence variability in response to warfarin or other drugs is not understood. Solutions to these challenges could lead to safer and more effective warfarin therapy. Unlike polymorphisms in our human genomes, gut microbial communities can be rapidly modified and therefore both the drug and the patient (via their microbiota) could be attuned for maximum therapeutic benefit. This application presents a plan to identify the specific microbial mechanisms that determine warfarin response. I have established a system to measure warfarin function in gnotobiotic mice, whose microbiota can be precisely manipulated. I have discovered that mice lacking gut microbes exhibit profound hyper-responsiveness to warfarin, consistent with a role for microbiota-derived vitamin K in this process. However, I also discovered altered regulation of drug metabolizing enzymes (DMEs), including the murine homolog of human CYP3A4 (Cyp3a11). Colonization of germfree mice with complete gut microbial communities normalizes warfarin function and DME expression. In Aim 1, this system will be used to determine the impact of interpersonal variation in microbiota-derived vitamin K on warfarin function. In Aim 2, I will define how gut microbial regulation of host DME gene expression impacts warfarin metabolism and function. Successful completion of these aims will address critical questions to explain frequent and dangerous adverse reactions to a widely used drug. Such an understanding could open the door to new approaches for optimizing warfarin dosing or gut community composition for safer pharmacology. Further, these studies will highlight host-microbiota interactions that could influence the function of other vitamin-K dependent processes and drugs.