Pichard L, Fabre I, Daujat M, Domergue J, Joyeux H, Maurel P
INSERM U-128, CNRS, Montpellier, France.
Mol Pharmacol. 1992 Jun;41(6):1047-55.
Prednisone, prednisolone, and methylprednisolone are currently administered in association with cyclosporin A in the postoperative treatment of transplant patients. The aim of this work was to evaluate the effects of these corticosteroids on the expression of several forms of cytochromes P450 (P450), including P450 1A2, 2D6, 2E1, and 3A, and on cyclosporin A oxidase activity in human liver. For this purpose, human hepatocytes prepared from lobectomies were maintained in culture in a serum-free medium, in collagen-coated dishes, for 96-144 hr, in the absence or presence of 50-100 microM corticosteroids, rifampicin, or dexamethasone. To mimic more closely the current clinical protocol, hepatocyte cultures were also co-treated with corticosteroids and cyclosporin A or ketoconazole (a selective inhibitor of P450 3A). Cyclosporin A oxidase activity, intracellular retention of cyclosporin A oxidized metabolites within hepatocytes, accumulation of P450 proteins and corresponding messages, and de novo synthesis and half-lives of these P450 were measured in parallel in these cultures. Our results, obtained from seven different hepatocyte cultures, showed that 1) dexamethasone and prednisone, but not prednisolone or methylprednisolone, were inducers of P450 3A, at the level of protein and mRNA accumulation, as well as of cyclosporin A oxidase activity, known to be predominantly catalyzed by these P450; 2) although corticosteroids are known to be metabolized in human liver, notably by P450 3A, partial or total inhibition of this P450 by cyclosporin or ketoconazole, respectively, did not affect the inducing efficiency of these molecules; 3) corticosteroids did not affect the half-life of P450 3A or the accumulation of other forms of P450, including 1A2, 2D6, and 2E1; 4) chronic treatment of cells with cyclosporin did not affect P450 3A accumulation; 5) corticosteroids were all competitive inhibitors of cyclosporin A oxidase in human liver microsomes, with Ki values of 61 +/- 12, 125 +/- 25, 190 +/- 38, and 210 +/- 42 microM for dexamethasone, prednisolone, prednisone, and methylprednisolone, respectively; and 6) chronic treatment of cells with corticosteroids did not influence the excretion of oxidized metabolites of cyclosporin from the cells. These results support most of clinical reports dealing with mutual interactions between cyclosporin A and corticosteroids.
目前，泼尼松、泼尼松龙和甲泼尼龙在移植患者的术后治疗中与环孢素A联合使用。这项研究的目的是评估这些皮质类固醇对几种细胞色素P450（P450）形式的表达的影响，包括P450 1A2、2D6、2E1和3A，以及对人肝脏中环孢素A氧化酶活性的影响。为此，将从肝叶切除术中获取的人肝细胞在无血清培养基中、胶原包被的培养皿中培养96 - 144小时，分别在不存在或存在50 - 100微摩尔皮质类固醇、利福平或地塞米松的情况下进行培养。为了更紧密地模拟当前的临床方案，肝细胞培养物还同时用皮质类固醇与环孢素A或酮康唑（P450 3A的选择性抑制剂）进行处理。在这些培养物中并行测量环孢素A氧化酶活性、环孢素A氧化代谢产物在肝细胞内的滞留、P450蛋白及其相应信息的积累，以及这些P450的从头合成和半衰期。我们从七种不同的肝细胞培养物中获得的结果表明：1）地塞米松和泼尼松，但不是泼尼松龙或甲泼尼龙，在蛋白质和mRNA积累水平以及已知主要由这些P450催化的环孢素A氧化酶活性方面，是P450 3A的诱导剂；2）尽管已知皮质类固醇在人肝脏中代谢，特别是由P450 3A代谢，但环孢素或酮康唑分别对该P450的部分或完全抑制并不影响这些分子的诱导效率；3）皮质类固醇不影响P450 3A的半衰期或其他形式的P450的积累，包括1A2、2D6和2E1；4）用环孢素对细胞进行长期处理不影响P450 3A的积累；5）皮质类固醇在人肝微粒体中均为环孢素A氧化酶的竞争性抑制剂，地塞米松、泼尼松龙、泼尼松和甲泼尼龙的Ki值分别为61±12、125±25、190±38和210±42微摩尔；6）用皮质类固醇对细胞进行长期处理不影响环孢素氧化代谢产物从细胞中的排泄。这些结果支持了大多数关于环孢素A与皮质类固醇之间相互作用的临床报告。
