TARGETED IMMUNOSUPPRESSION USING DEXTRAN PRODRUGS

描述(改编自《调查者摘要》)：长期目标 申请者的目的是使用葡聚糖聚合物作为大分子前药 靶向和/或持续递送药物治疗剂。这个 本应用的具体目的是研究葡聚糖的可行性。 用于将免疫抑制药靶向输送到肝脏的前药，使用 甲基强的松龙(MP)作为模型药物。它被假设为 Mp的葡聚糖前体药物会在肝脏中积聚，在那里它会释放出游离的 MP逐渐增加，导致持续的局部免疫抑制，这将 有益于肝移植。为了验证这一假设，首先， 右旋糖酐-甲基强的松龙琥珀酸酯(DEX-MPS)将由以下方法制备 甲基强的松龙琥珀酸酯(MPS)与70kD葡聚糖的偶联。 第二，DEX-MPS的优先积累和随后的释放 肝脏中的MP将通过体外研究在大鼠的血液、血清和 肝脏溶酶体及大鼠单次给药后的体内实验 (相当于5 mg/kg MP)DEX-MPS。第三，DEX-MPS对 全身和局部免疫系统将在体内进行测试 给予类似剂量的前药。对于系统性影响， 免疫抑制的时间进程将用脾来量化 淋巴细胞增殖试验。对于局部效果， 释放细胞因子(白介素1和白介素6) 内毒素刺激的离体灌流大鼠肝脏将 下定决心。为了进行比较，相似的处理方式和药理数据将 在给予等量的免费MP后收集。这个 生物样品中MP、NOS和DEX-MPS的浓度将 使用特定的层析方法测定，并适当地 将估计药代动力学和药效学参数。这个 这些研究的结果将被用来评估 右旋糖苷-免疫抑制剂结合物在局部免疫抑制中的应用 肝脏。

DESCRIPTION (Adapted from Investigator's Abstract): The long-term objective of the applicant is to use dextran polymers as macromolecular prodrugs for targeted and/or sustained delivery of pharmacotherapeutic agents. The specific purpose of this application is to study the feasibility of dextran prodrugs for targeted delivery of immunosuppressants to the liver, using methylprednisolone (MP) as a model drug. It is hypothesized that the dextran prodrug of MP would accumulate in the liver, where it releases free MP gradually, resulting in a sustained, local immunosuppression which would be beneficial in liver transplantation. To test this hypothesis, first, dextran-methylprednisolone succinate (DEX-MPS) will be prepared by conjugation of methylprednisolone succinate (MPS) with a 70 kD dextran. Second, the preferential accumulation of DEX-MPS and subsequent release of MP in the liver will be tested by in vitro studies in rat blood, serum, and liver lysosomes, and by in vivo experiments in rats after single doses (equivalent to 5 mg/kg MP) of DEX-MPS. Third, the effects of DEX-MPS on the systemic and local immune systems will be tested after in vivo administration of a similar dose of the prodrug. For systemic effects, the time course of immunosuppression will be quantitated by using the spleen lymphocyte proliferation test. For local effects, the time course of the release of cytokines (interleukin-1 and interleukin-6) from lipopolysaccharide-challenged isolated perfused rat livers will be determined. For comparison, similar disposition and pharmacologic data will be collected after the administration of equivalent doses of free MP. The concentrations of MP, NOS, and DEX-MPS in biological samples will be determined using specific chromatographic methods, and appropriate pharmacokinetic and pharmacodynamic parameters will be estimated. The results of these studies will be used to assess the potential role of dextran-immunosuppressant conjugates in local immunosuppression of the liver.