Internal Medicine-Nephrology, University Hospital of Patras, Patras, Greece.
Ren Fail. 2010 Jul;32(6):727-32. doi: 10.3109/0886022X.2010.486487.
The exact mechanism of cyclosporine (CsA) nephrotoxicity has not been clarified. In this study, we investigated the effect of pharmacological doses of CsA on the production of nitric oxide synthases (NOSs) and endothelin (ET) receptors (ETR-A, ETR-B), in human tubular cells [human kidney (HK)-2], to identify any implication of these pathways in CsA nephrotoxicity.
Human tubular epithelial cells (HK-2) were cultured in the presence of CsA at various concentrations (0-1000 ng/mL). Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to determine mRNA synthesis of NOSs (eNOS, iNOS) and ET receptors (ETR-A, ETR-B) and western blot analysis for the subsequent proteins.
A dose-dependent induction of synthesis of NO synthases eNOS and iNOS and ET receptors ETR-A and ETR-B was observed, even at therapeutic doses of CsA. An interaction between NO and ET-1 systems under the influence of CsA was also observed. Blockage of NO production was followed by down-regulation of ETR-B whereas blockade of ET pathway with ET receptor antagonists was followed by down-regulation of eNOS expression.
CsA induces NOSs as well as ET receptor mRNA and protein synthesis in tubular epithelial cells. The up-regulation of NO and ET-1 pathways is probably implicated in the nephrotoxic action of CsA, whereas an interplay between ETR-B and eNOS seems to be involved.
环孢素（CsA）肾毒性的确切机制尚未阐明。在这项研究中，我们研究了药理剂量的 CsA 对人肾小管细胞[人肾（HK）-2]中一氧化氮合酶（NOSs）和内皮素（ET）受体（ETR-A、ETR-B）产生的影响，以确定这些途径在 CsA 肾毒性中的任何作用。
将人肾小管上皮细胞（HK-2）在不同浓度（0-1000ng/mL）的 CsA 存在下培养。逆转录聚合酶链反应（RT-PCR）用于确定 NOSs（eNOS、iNOS）和 ET 受体（ETR-A、ETR-B）的 mRNA 合成，随后进行 Western blot 分析。
观察到 NO 合酶 eNOS 和 iNOS 以及 ET 受体 ETR-A 和 ETR-B 的合成呈剂量依赖性诱导，即使在 CsA 的治疗剂量下也是如此。还观察到在 CsA 的影响下 NO 和 ET-1 系统之间的相互作用。NO 产生的阻断随后导致 ETR-B 的下调，而 ET 途径的阻断用 ET 受体拮抗剂随后导致 eNOS 表达的下调。
CsA 诱导肾小管上皮细胞中 NOSs 以及 ET 受体 mRNA 和蛋白的合成。NO 和 ET-1 途径的上调可能与 CsA 的肾毒性作用有关，而 ETR-B 和 eNOS 之间的相互作用似乎也参与其中。
