DETERMINANTS FOR TOXICITY OF CALCINEURIN INHIBITORS

免疫抑制剂对钙调神经磷酸酶活性的抑制作用 CyA和FK506导致这些药物的治疗和毒性作用 毒品。这项提案的主要目标是确定如何 不同细胞的参数会影响CyA和FK506的效力，如 钙调神经磷酸酶抑制剂。第二个目标是确定 钙调神经磷酸酶抑制的不同补偿能力 有助于细胞类型对环磷酰胺毒性效应的敏感性 和FK506。从长远来看，这些信息将有助于减少 CyA/FK506毒副作用的数量和严重程度，并扩大 应用钙调神经磷酸酶抑制剂进行免疫抑制治疗的有效性。 环孢素A(CyA)和FK506显著提高了治疗的成功率 移植后移植物存活率。这些药物被用来 支持当今执行的几乎每一项传输，尽管 药物的毒性可导致停止治疗和 将移植物和患者置于危险之中。既有治疗作用，也有毒性 这些药物的作用是细胞类型和组织选择性的，具有细胞类型 CyA/FK506作为钙调神经磷酸酶抑制剂的特异性差异 预测对选择性有贡献。钙调神经磷酸酶的抑制作用 CyA/FK506在力学上是复杂的，依赖于 药物及其蛋白质辅因子的浓度(称为 免疫亲和素)的抑制作用。钙调神经磷酸酶的活性物种 抑制是一种药物-免疫亲和素复合体，它与钙调神经磷酸酶结合。 一种钙依赖的方式。这项研究的假设是 细胞内免疫亲和素的含量以及钙离子的持续时间和幅度 瞬时，决定CyA/FK506作为钙调神经磷酸酶抑制剂的效力。 进一步假设，CyA的毒性依赖于 钙调神经磷酸酶抑制程度和细胞 弥补钙调神经磷酸酶活性的丧失。这一行动的具体目标 项目包括： I.确定钙调神经磷酸酶是否与CyA-亲环素和FK506结合- FKPB络合物是由存在于非 活动单元格。 II.定量测定亲环素的浓度依赖性 用CyA抑制钙调神经磷酸酶并测定细胞内容物 细胞中的亲环素或亲环素的类型会影响CyA的效力。 测量组织和细胞的补偿能力 钙调神经磷酸酶抑制作用及其底物的鉴定 对CyA敏感的细胞。 预计，对潜在机制的理解 钙调神经磷酸酶抑制将澄清为什么某些器官是 免疫抑制剂的毒性作用，将揭示更多更好的 治疗干预的地点，并将指明哪种佐剂 治疗可能在改善CyA/FK506侧最成功 效果。

Inhibition of calcineurin phosphatase activity by the immunosuppressants CyA and FK506 causes both the therapeutic and toxic effects of these drugs. The primary objective of this proposal is to determine how parameters which vary from cell to cell affect CyA and FK506 potency as calcineurin inhibitors. A second objective is to determine if differential abilities to compensate for calcineurin inhibition contribute to the cell type-specific sensitivity to toxic effects of CyA and FK506. In the long term, this information will help reduce the number and severity of CyA/FK506 toxic side effects and expand the usefulness of immunosuppressive therapy with calcineurin inhibitors. Cyclosporin A (CyA) and FK506 have dramatically increased the success rate for graft survival after transplantation. These drugs are used to support virtually every transport performed today, despite severe toxicity of the drugs which can result in withdrawal of treatment and place the graft and patients at risk. Both the therapeutic and toxic effects of these drugs are cell type and tissue selective, with cell type specific differences in potency of CyA/FK506 as calcineurin inhibitors predicted to contribute to the selectivity. Calcineurin inhibition by CyA/FK506 is mechanistically complex, being dependent on the concentrations of both the drug and its protein cofactor (referred to as an immunophilin) in the inhibition. The active species for calcineurin inhibition is a drug-immunophilin complex which binds to calcineurin in a Ca2+-dependent manner. The hypothesis for this study is that the cellular content of immunophilin, and the duration and amplitude of Ca2+ transients, determine the potency of CyA/FK506 as calcineurin inhibitors. It is further hypothesized that CyA toxicity is dependent both on the degree of calcineurin inhibition and the ability of the cell to compensate for loss of calcineurin activity. Specific aims of this project are: I. To determine if calcineurin binding to CyA-cyclophilin and FK506- FKPB complexes is supported by the Ca2+ concentrations present in non- active cells. II. To quantitate the cyclophilin concentration dependence of calcineurin inhibition by CyA and determine if the cell content of cyclophilin or the type of cyclophilin in the cell affect CyA potency. III. To measure the capacity of tissues and cells to compensate for calcineurin inhibition and the identify unique calcineurin substrates in cells which are sensitive to CyA. It is anticipated that an understanding of the mechanisms underlying calcineurin inhibition will clarify why certain organs are targets for the toxic effects of immunosuppressants, will reveal more and better sites for therapeutic intervention and will indicate which adjuvant therapies might be most successful in ameliorating the CyA/FK506 side effects.