Department of Urology, New York Medical College, Valhalla, New York 10595, USA.
J Endourol. 2010 Mar;24(3):339-45. doi: 10.1089/end.2009.0205.
Calcium oxalate (CaOx) is one of the key elements for kidney stone formation, but the exact mechanism needs to be defined. CaOx has been shown to cause renal cell injury through oxidative stress, leading to potential crystal deposition in the kidneys. We thus investigated if CaOx crystal would induce such renal cell injury in vitro and also explored how it would be carried out.
Renal tubular epithelial LLC-PK(1) cells were employed, and CaOx monohydrate (COM) was used as CaOx crystal in this study. Cytotoxic effects of COM were assessed on cell viability and biochemical parameters, while protective effect of antioxidants against COM was also examined.
COM demonstrated its cytotoxicity on LLC-PK(1) cells, exhibiting a approximately 35% cell viability reduction with 500 microg/mL COM in 6 hours. This was presumably attributed to oxidative stress, indicated by lipid peroxidation assay, and N-acetylcysteine (NAC), a potent antioxidant, indeed neutralized such COM cytotoxicity. Although COM also induced inactivation of glutathione-dependent enzymes and partial degradation of heat shock protein 90, these adverse effects were completely prevented with NAC. Moreover, such reduced cell viability with COM was rather associated with apoptosis, evidenced by DNA analysis.
COM is cytotoxic to LLC-PK(1) cells through oxidative stress, leading to the cell viability reduction, adverse effects on biochemical parameters, and, consequently, apoptosis. However, NAC effectively averted such severe cytotoxic effects, sustaining the renal cell integrity. Thus, NAC may provide full renoprotection against COM assault, preventing renal cell injury and ultimate stone formation.
草酸钙（CaOx）是肾结石形成的关键因素之一，但确切的机制仍需进一步明确。已有研究表明，CaOx 可通过氧化应激导致肾细胞损伤，从而导致潜在的晶体在肾脏中沉积。因此，我们研究了 CaOx 晶体是否会在体外引起这种肾细胞损伤，并探讨了其具体作用机制。
本研究采用肾小管上皮细胞系 LLC-PK(1)，以一水合草酸钙（COM）作为 CaOx 晶体。通过细胞活力和生化参数评估 COM 的细胞毒性，同时还研究了抗氧化剂对 COM 细胞毒性的保护作用。
COM 对 LLC-PK(1)细胞表现出细胞毒性，在 6 小时内，500μg/mL COM 可使细胞活力降低约 35%。这可能归因于氧化应激，通过脂质过氧化测定法证实了这一点，而 N-乙酰半胱氨酸（NAC）作为一种有效的抗氧化剂，确实能中和 COM 的细胞毒性。尽管 COM 还诱导了谷胱甘肽依赖酶的失活和热休克蛋白 90 的部分降解，但 NAC 完全阻止了这些不良反应。此外，COM 引起的细胞活力降低与细胞凋亡有关，这一点可以通过 DNA 分析得到证实。
COM 通过氧化应激对 LLC-PK(1)细胞具有细胞毒性，导致细胞活力降低、生化参数异常，最终导致细胞凋亡。然而，NAC 可有效避免 COM 引起的严重细胞毒性作用，维持肾细胞的完整性。因此，NAC 可能为 COM 攻击提供全面的肾保护作用，预防肾细胞损伤和最终的结石形成。
