Gut Microbiota and Effect on Immune Suppressants in Transplantation

霉酚酸酯(MMF)和他克莫司是90%以上肾脏使用的主要免疫抑制剂 移植(TX)。一些研究表明，低霉酚酸(MPA，活性)与 12小时曲线下面积(AUC)和急性同种异体移植 拒绝。然而，AS患者MMF的药代动力学(Pk)存在显著的个体差异。 在相同剂量下，AUC的变化相当于10倍。Mpa浓度升高与以下因素有关 一些有毒性的研究，如腹泻、白细胞减少和贫血。PK研究显示MPA出现第二个峰值 口服MMF后6-8小时，由于其酚类物质在胆汁中的排泄，MMF从肝肠循环(EHR)中排出。 葡萄糖醛酸苷(MPAG，甲孕酮的主要非活性代谢产物)。EHR是通过β-葡萄糖糖醛酸脂的水解而发生的。 肠道细菌产生的葡萄糖醛酸苷酶与甲孕酮的重吸收。广泛的EHR极大地增加了系统性 暴露于甲氧基安非他明可能会增加免疫抑制和毒性。β-葡萄糖醛酸苷酶是由 肠道微生物无乳链球菌、产气荚膜梭菌和大肠杆菌，已知会影响药物 底物和潜在的EHR范围。在对TX患者粪便的初步研究中，类杆菌， 在伴有腹泻的TX患者中，瘤胃球菌、辅球菌和Dorea显著降低。具体的 假说是，粪便微生物区系的某些模式会导致EHR增加，更多的MPA全身暴露 和毒物。因此，我们将确定微生物组与：Mpa和代谢产物PK posttx的相关性 和EHR(目标1)和甲孕酮相关毒性，如贫血和白细胞减少(目标2)。最后，我们将 确定微生物群多样性与接受甲氨蝶呤治疗后腹泻的相关性(目标3)。一个 将开发具有连续粪便微生物组样本的新肾脏TXs的预期队列，并将MPA和 测定代谢物PK和EHR(目标1)，随后评估白细胞减少和贫血(目标2)。 我们将测量一系列粪便微生物群与术后腹泻的相关性(目标3)。所有的科目都将是 随访12个月，评估与长期肾脏相关的肾小球滤过率。 结果。将使用创新的、针对所有目标的鸟枪测序来确定微生物组，以及 目标3真菌的内部转录间隔区2(ITS2)基因测序。我们将使用 微生物β-葡萄糖醛酸苷酶，用RNAseq来阐明微生物组通过 影响甲孕酮暴露，以及甲孕酮相关的白细胞减少和贫血，以及血栓后腹泻。我们会收集 使用短信以患者为中心的腹泻结果。到研究结束时，我们将开发出 微生物区系模式，可用作预测测试，以确定何时需要进行MPA PK评估， 选择甲孕酮的剂量将毒性降至最低。这项研究可能会导致未来使用选定的抗生素或粪便 移植以恢复微生物群，从而确保正常的药物处置和最低限度的与MPA相关的 毒物。我们将创建一个模型来研究其他经历过EHR或已经受到干扰的药物 由于微生物群的吸收或分布。

Myocphenolate mofetil (MMF) and tacrolimus are the main immune suppressants used in over 90% of kidney transplants (tx). Several studies have shown an association between low mycophenolic acid (MPA, active metabolite of MMF) exposure as measured by 12 hour area-under-the-curve (AUC) and acute allograft rejection. However, significant inter-individual variation in the pharmacokinetics (PK) of MMF exists with as much as a 10-fold variation in AUC with the same dose. Elevated MPA concentrations have been associated in some studies with toxicities such as diarrhea, leukopenia and anemia. PK studies show a second peak of MPA 6-8 hours after oral MMF from enterohepatic recycling (EHR) of MPA due to biliary excretion of its phenolic glucuronide (MPAG, major inactive metabolite of MPA). EHR occurs by hydrolysis of the glucuronide by β- glucuronidases produced by gut bacteria and reabsorption of MPA. Extensive EHR greatly increases systemic exposure to MPA and likely enhances immunosuppression and toxicity. β-glucuronidases are produced by the gut microbes Streptococcus agalactiae, Clostridium perfringens, and E. coli and are known to influence drug substrates and potentially the extent of EHR. In a pilot study of stool from tx patients, Bacteroides, Ruminococcus, Coprococcus, and Dorea were significantly lower in tx patients with diarrhea. The specific hypothesis is that certain patterns of stool microbiota lead to increased EHR, greater MPA systemic exposure and toxicities. Therefore, we will determine the association of microbiome with: MPA and metabolite PK posttx and EHR (Aim 1) and MPA associated toxicities such as anemia and leukopenia posttx (Aim 2). Lastly we will determine the association of microbiome diversity with diarrhea in tx recipients on MPA posttx (Aim 3). A prospective cohort of new kidney txs with serial stool microbiome samples will be developed and MPA and metabolite PK and EHR measured (Aim 1), and subsequent assessment of leukopenia and anemia (Aim 2). We will measure serial stool microbiome for association with diarrhea posttx (Aim 3). All subjects will be followed for 12 months posttx for estimated glomerular filtration rate which is associated with long-term kidney outcomes. The microbiome will be determined using innovative, shotgun sequencing for all aims, along with Internal Transcribed Spacer 2 (ITS2) gene sequencing for fungi for Aim 3. We will use metatranscriptomics of microbial β-glucuronidases, using RNAseq, to elucidate the mechanism through which the microbiome influences MPA exposure, and MPA associated leukopenia and anemia, and posttx diarrhea. We will collect patient centered outcomes of diarrhea using text messaging. By the end of the study, we will have developed microbiota patterns that could be utilized as a predictive test for when MPA PK assessment is needed, for selection of MPA dose to minimize toxicities. This study can lead to future use of select antibiotics or fecal transplants to restore the microbiome thereby assuring normalized drug disposition and minimal MPA related toxicities. We will have created a model to study other drugs that undergo EHR or which have perturbed absorption or distribution due to the microbiome.