Aihara Kinue, Byer Karen J, Khan Saeed R
Department of Pathology, College of Medicine, University of Florida, Gainesville, Florida 32610, USA.
Kidney Int. 2003 Oct;64(4):1283-91. doi: 10.1046/j.1523-1755.2003.00226.x.
Crystal formation and retention are critical events for the formation of kidney stones. Oxalate and calcium oxalate (CaOx) crystals are injurious to renal epithelium, and membranes of injured cells promote crystal adherence and retention. Calcium phosphate (CaP) is the most common crystal in both urine and stones, most likely to form in the early segments of the nephron and can nucleate CaOx in a metastable solution. We hypothesized that CaP can also injure the renal epithelial cells.
We exposed proximal tubular origin line derived from pig proximal tubules (LLC-PK1), and collecting duct origin Madin-Darby canine kidney (MDCK) cell lines to various concentrations of Brushite (Br) crystals and investigated staining with Trypan Blue and the release of lactate dehydrogenase (LDH) into the medium as an indicator of injury. In order to determine the involvement of reactive oxygen species, we also measured LDH release in the presence of superoxide dismutase (SOD) and production of hydrogen peroxide (H2O2) and 8-isoprostane (8-IP) in the presence of the catalase.
Exposure to Br crystals was associated with LDH release by both cell types, induced the production of H2O2 and 8-IP. Presence of SOD and catalase reduced LDH release as well as staining with trypan blue. Catalase was also associated with reduced production of H2O2 and 8-IP.
Brushite crystals are injurious to cells of both the proximal tubules as well as collecting ducts. Injury is mediated by reactive oxygen species. We propose that CaP crystals can independently interact with renal epithelium, promote sites for crystal attachment, and then either grow into mature CaP stones or create sites for CaOx crystal nucleation, retention, and stone development.
晶体形成和滞留是肾结石形成的关键事件。草酸盐和草酸钙（CaOx）晶体对肾上皮细胞具有损伤作用，受损细胞的膜促进晶体黏附和滞留。磷酸钙（CaP）是尿液和结石中最常见的晶体，最有可能在肾单位的早期节段形成，并且可以在亚稳溶液中使CaOx成核。我们推测CaP也会损伤肾上皮细胞。
我们将源自猪近端小管的近端小管起源细胞系（LLC-PK1）和集合管起源的Madin-Darby犬肾（MDCK）细胞系暴露于不同浓度的透钙磷石（Br）晶体，并研究了台盼蓝染色以及乳酸脱氢酶（LDH）释放到培养基中作为损伤指标的情况。为了确定活性氧的参与情况，我们还测量了超氧化物歧化酶（SOD）存在时的LDH释放以及过氧化氢酶存在时过氧化氢（H2O2）和8-异前列腺素（8-IP）的产生。
暴露于Br晶体与两种细胞类型的LDH释放相关，诱导了H2O2和8-IP的产生。SOD和过氧化氢酶的存在减少了LDH释放以及台盼蓝染色。过氧化氢酶还与H2O2和8-IP产生的减少有关。
透钙磷石晶体对近端小管和集合管的细胞均有损伤作用。损伤由活性氧介导。我们提出CaP晶体可以独立地与肾上皮细胞相互作用，促进晶体附着位点，然后要么生长为成熟的CaP结石，要么为CaOx晶体成核、滞留和结石形成创造位点。
