Division of Clinical Pharmacology and Toxicology, The Hospital for Sick Children, Toronto, Ontario, Canada.
Transl Res. 2011 Nov;158(5):290-301. doi: 10.1016/j.trsl.2011.07.002. Epub 2011 Aug 3.
For decades, acyclovir-induced nephrotoxicity was believed to be secondary to crystalluria. Clinical evidence of nephrotoxicity in the absence of crystalluria suggests that acyclovir induces direct insult to renal tubular cells. We postulated that acyclovir is metabolized by the alcohol dehydrogenase (ADH) enzyme to acyclovir aldehyde, which is metabolized by the aldehyde dehydrognase 2 (ALDH2) enzyme to 9-carboxymethoxymethylguanine (CMMG). We hypothesized that acyclovir aldehyde plays a role in acyclovir-induced nephrotoxicity. Human renal proximal tubular (HK-2) cells were used as our in vitro model. Western blot and enzymes activities assays were performed to determine whether the HK-2 cells express ADH and ALDH2 isozymes, respectively. Cytotoxicity (measured as a function of cell viability) assays were conducted to determine (1) whether the acyclovir aldehyde plays a role in acyclovir-induced nephrotoxicity and (2) whether CMMG induces cell death. A colorimetric assay was performed to determine whether acyclovir was metabolized to an aldehyde in vitro. Our results illustrated that (1) HK-2 cells express ADH and ALDH2 isozymes, (2) 4-methylpyrazole rendered significant protection against cell death, (3) CMMG does not induce cell death, and (4) acyclovir was metabolized to an aldehyde in tubular cells. These data indicate that acyclovir aldehyde is produced in HK-2 cells and that inhibition of its production by 4-methylpyrazole offers significant protection from cell death in vitro, suggesting that acyclovir aldehyde may cause the direct renal tubular insult associated with acyclovir.
几十年来，人们一直认为阿昔洛韦诱导的肾毒性是结晶尿引起的。在没有结晶尿的情况下出现肾毒性的临床证据表明，阿昔洛韦直接损害肾小管细胞。我们推测，阿昔洛韦被醇脱氢酶（ADH）代谢为阿昔洛韦醛，然后被醛脱氢酶 2（ALDH2）代谢为 9-羧甲氧基甲基鸟嘌呤（CMMG）。我们假设阿昔洛韦醛在阿昔洛韦诱导的肾毒性中起作用。我们使用人肾近端小管（HK-2）细胞作为体外模型。进行 Western blot 和酶活性测定，以确定 HK-2 细胞是否分别表达 ADH 和 ALDH2 同工酶。进行细胞毒性（作为细胞活力的函数进行测量）测定，以确定（1）阿昔洛韦醛是否在阿昔洛韦诱导的肾毒性中起作用，以及（2）CMMG 是否诱导细胞死亡。进行比色测定以确定阿昔洛韦是否在体外代谢为醛。我们的结果表明：（1）HK-2 细胞表达 ADH 和 ALDH2 同工酶，（2）4-甲基吡唑可显着防止细胞死亡，（3）CMMG 不会诱导细胞死亡，以及（4）阿昔洛韦在肾小管细胞中代谢为醛。这些数据表明阿昔洛韦醛在 HK-2 细胞中产生，并且 4-甲基吡唑抑制其产生可显着防止体外细胞死亡，表明阿昔洛韦醛可能导致与阿昔洛韦相关的直接肾小管损伤。
