Developmental Regulation of Drug Metabolism by Targeting the Gut Microbiome

描述（由申请人提供）：关于肝脏中药物代谢酶和转运体（统称为“药物加工基因”[DPGs]）的发育调控知之甚少，使新生儿和儿童处于更高的药物不良反应（adr）风险中。利用RNA-Seq，我们发现药物代谢是无菌（GF）小鼠整个肝脏转录组中最重要的差异调控途径，这表明肠道微生物组与肝脏DPGs之间存在一种新的相互作用。肠道微生物群的关键功能之一是产生次生胆汁酸（BAs），它可以激活肝脏中两个最关键的外源感应核受体，即妊娠X受体（PXR）和组成型雄烷受体（CAR）。在发育过程中，肠道细菌和次级BA谱发生了深刻的变化，这表明肠道微生物组可能至少在一定程度上参与了肝脏DPGs的发育调节。目前还没有系统的研究来描述肠道微生物组在发育过程中对所有DPGs的调节，并且关于抗生素或益生菌靶向肠道微生物组如何重新编程肝脏中DPGs的发生也知之甚少。因此我们的目标是

DESCRIPTION (provided by applicant): Very little is known about the developmental regulation of drug-metabolizing enzymes and transporters (together called "drug-processing genes" [DPGs]) in liver, placing newborns and children at a much higher risk of adverse drug reactions (ADRs). Using RNA-Seq, we have shown that drug metabolism is the top most differentially regulated pathway in the entire liver transcriptome of germ-free (GF) mice, suggesting that there is a novel interaction between gut microbiome and hepatic DPGs. One of the key functions of gut microbiome is to produce secondary bile acids (BAs), which can activate two most critical xenobiotic-sensing nuclear receptors in liver, namely the pregnane X receptor (PXR) and constitutive androstane receptor (CAR). During development, profound changes occur in the intestinal bacteria and the secondary BA profiles, suggesting that gut microbiome may at least in part contribute to the developmental regulation of DPGs in liver. No systematic studies have been performed to characterize the regulation of all DPGs by gut microbiome during development, and little is known regarding how targeting the gut microbiome by antibiotics or probiotics re- programs the ontogeny of DPGs in liver. Therefore the goal of this research is to utilize multidisciplinary approaches, including GF and genetically-engineered mice, BA metabolomics, Next-Generation Sequencing, and human fecal samples, to unveil the role of gut microbiota in modulating PXR and CAR signaling and the subsequent ontogenic re-programming of DPGs in liver. Our central hypothesis is: the developmental changes in the gut microbiome at least in part contribute to the regulation of the ontogeny of DPGs in liver, through altering secondary BAs in the gut to modify the PXR and/or CAR signaling in liver. We will test our hypothesis in 2 Aims: Aim 1A will use RNA-Seq to quantify mRNAs of 281 critical DPGs in livers of GF and conventional (Conv) mice at 6 developmental ages, and validate the proteins and activities of differentially regulated DPGs. We will also use ChIP-Seq to quantify how gut bacteria modulate PXR/CAR DNA binding to certain DPGs, and correlate DPG ontogeny with the ontogeny of gut microbiome (metagenomics) and BA profiles (UPLC-MS/MS). Aim 1B will introduce secondary BAs to GF mice in various PXR- and CAR-knockout and humanized transgenic) at various ages to test our hypothesis that secondary BAs restore the normal ontogeny of certain DPGs. Aim 2 will use GF mice colonized with human fecal bacteria from various developmental ages, to determine the roles of antibiotics and the probiotic L. acidophilus in re-programming the ontogeny of human microbiome and the subsequent changes in the host DPGs during liver development. The proposed work will unveil a novel link between the ontogeny of gut microbiome and the developmental changes of drug- processing capacities during development, and will lead to a paradigm shift in pediatric pharmacology, by establishing a new concept in considering ADRs in children, which are the "bug-drug" interactions, in addition to the known "drug-drug" and "food-drug" interactions.