Role and Relevance of Pept1 in Drug Absorption, Disposition, and Dynamics

描述(申请人提供)：PEPT1是SLC15家族的一种质子偶联寡肽转运体(POT)，具有重要的营养价值，因为它能从饮食中吸收小肽，并能从肾脏的肾小球滤液中重吸收多肽结合的氨基氮。PEPT1还具有运输治疗性药物(如β-内酰胺类抗生素、血管紧张素转换酶抑制剂、抗病毒核苷前体药物)和潜在毒性多肽类药物(如5-氨基乙酰丙酸)的药理学意义。然而，POT家族的其他成员(即PEPT2、PHT1和PHT2)在肠道和肾脏表达，从而混淆了对其作用和相关性的准确评估。我们实验室最近建立了一个PEPT1基因敲除小鼠群体，这是一个独特的资源，可以用活体全动物实验来验证原位机制研究。考虑到最近PEPT1结肠表达异常与炎症性肠病进展之间的关联，这些基因敲除小鼠的可获得性尤其令人兴奋。考虑到这一点，这种“重新提交”应用的长期目标是定义PEPT1的生理、药理和病理作用及其相关性。我们的工作假设是，PEPT1是多肽和多肽类药物在肠道吸收、处置和动力学过程中的关键转运体，在肠道炎症的发病机制中发挥着重要作用。为了验证这一假说，提出了以下具体目标：目的1.确定多肽类药物(和前药)、细菌衍生多肽和抗炎三肽的在体肠道转运特性；目的2.表征多肽类药物(和前药物)和抗炎三肽在体内的吸收和处置；以及目的3.评价PEPT1在介导细菌衍生多肽和抗炎三肽炎症反应中的作用和相关性。通过结合野生型和PEPT1基因缺失小鼠的细胞/组织、分子和整体动物研究，拟议的研究将极大地促进我们对PEPT1(相对于其他转运体和/或被动过程)在体内的作用、意义和PEPT1对多肽、多肽类药物(和前体药物)的载体运输的理解。此外，我们的发现将为PEPT1介导的肠炎症机制提供重要的新见解，并因此为炎症性肠病的治疗策略确定新的靶点。最后，拟议的研究可能会提供难得的洞察力，了解具有遗传多态的人类受试者多肽/模拟动力学和反应的可变性。

DESCRIPTION (provided by applicant): PEPT1, a proton-coupled oligopeptide transporter (POT) of the SLC15 family, has nutritional importance because of its intestinal absorption of small peptides from the diet and because of its reabsorption of peptide-bound amino nitrogen from glomerular filtrate in kidney. PEPT1 also has pharmacological significance in its ability to transport therapeutic agents (e.g., ?-lactam antibiotics, angiotensin-converting enzyme inhibitors, antiviral nucleoside prodrugs) and potentially toxic peptidomimetics (e.g., 5-aminolevulinic acid). However, other members of the POT family (i.e., PEPT2, PHT1 and PHT2) are expressed in the intestine and kidney, thereby confounding an accurate assessment of its role and relevance. Our laboratory has recently established a colony of PEPT1 knockout mice, a unique resource in which to validate in situ mechanistic studies with in vivo whole animal experiments. The availability of these knockout mice is particularly exciting given the recent association of aberrant PEPT1 colonic expression and inflammatory bowel disease progression. With this in mind, the long-term objectives of this "resubmission" application are to define the physiological, pharmacological, and pathological roles and relevance of PEPT1. Our working hypothesis is that PEPT1 is a critical transporter in the intestinal absorption, disposition, and dynamics of peptides and peptide-like drugs, and that it plays an important role in the pathogenesis of intestinal inflammation. To test this hypothesis, the following specific aims are proposed: Aim 1. To determine the in situ intestinal transport properties of peptide-like drugs (and prodrugs), bacterially-derived peptides, and anti- inflammatory tripeptides; Aim 2. To characterize the in vivo absorption and disposition of peptide-like drugs (and prodrugs), and anti-inflammatory tripeptides; and Aim 3. To evaluate the role and relevance of PEPT1 in mediating the inflammatory response to bacterially-derived peptides and anti-inflammatory tripeptides. By combining cellular/tissue, molecular, and whole animal studies in wild-type and PEPT1 null mice, the proposed studies will greatly advance our understanding of the in vivo role, significance and vectorial transport of peptides, peptide-like drugs (and prodrugs) by PEPT1 (as opposed to other transporters and/or passive processes). Moreover, our findings will provide important new insights into the mechanisms of PEPT1- mediated intestinal inflammation and, as a result, identify a new target for therapeutic strategies against inflammatory bowel disease. Finally, the proposed studies may offer rare insight into the variability of peptide/mimetic kinetics and response in those human subjects with genetic polymorphisms.