Umekawa Tohru, Chegini Nasser, Khan Saeed R
Department of Pathology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida 32610-0275, USA.
Kidney Int. 2002 Jan;61(1):105-12. doi: 10.1046/j.1523-1755.2002.00106.x.
Crystals of calcium oxalate monohydrate (COM) and excess oxalate ions (OX) stimulate an array of responses inducing localized injury and inflammation in the kidneys. These inflammatory responses are key regulators of development of nephrolithiasis. We propose that monocyte chemoattractant protein-1 (MCP-1), a chemokine with potent chemotactic activity for monocytes/macrophages, is a mediator of local inflammatory responses to COM and OX-induced injury. To test this hypothesis, the effects of COM and OX on the expression of MCP-1 mRNA and protein by NRK52E rat renal tubular cells were investigated.
Confluent cultures of NRK52E cells were exposed to COM (33 to 267 microg/cm2) or OX (125 to 1000 micromol/L, estimated free oxalate levels of 65.8 to 540 micromol/L) and catalase (400 or 2000 U/mL), a free radical scavenger that protects the cells against detrimental effects of COM and OX, for 1 to 48 hours under serum free conditions. The conditioned media were collected and total cellular RNA isolated from the cells and subjected to enzyme-linked immunosorbent assay (ELISA) and semiquantitative polymerase chain reaction (PCR) to determine the expression of MCP-1 protein and mRNA, respectively.
NRK52E cells express MCP-1 mRNA and protein, and the level of their expression significantly increases following treatments with COM and OX in a time and concentration dependent manner. MCP-1 mRNA expression and protein production increased more significantly after exposure to COM than to OX. These responses were significantly reduced following treatments with catalase (2000 U/mL).
NRK52E cells express MCP-1 mRNA and protein, and their levels are altered following COM and OX exposure. Since catalase treatment reduced MCP-1 expression, free radicals may be involved in the up-regulation of MCP-1 production by the epithelial cells. The results suggest that elevated expression of MCP-1, which is often associated with local inflammatory response, may mediate similar reactions including attraction of macrophages seen around the interstitial crystals during the early stages of nephrolithiasis.
一水合草酸钙（COM）晶体和过量草酸根离子（OX）会引发一系列反应，导致肾脏局部损伤和炎症。这些炎症反应是肾结石形成过程中的关键调节因素。我们推测单核细胞趋化蛋白-1（MCP-1），一种对单核细胞/巨噬细胞具有强大趋化活性的趋化因子，是COM和OX诱导损伤的局部炎症反应的介质。为了验证这一假设，我们研究了COM和OX对NRK52E大鼠肾小管细胞中MCP-1 mRNA和蛋白表达的影响。
将汇合的NRK52E细胞培养物在无血清条件下暴露于COM（33至267μg/cm²）或OX（125至1000μmol/L，估计游离草酸水平为65.8至540μmol/L）以及过氧化氢酶（400或2000 U/mL），一种自由基清除剂，可保护细胞免受COM和OX的有害影响，持续1至48小时。收集条件培养基，从细胞中分离总细胞RNA，并分别进行酶联免疫吸附测定（ELISA）和半定量聚合酶链反应（PCR），以确定MCP-1蛋白和mRNA的表达。
NRK52E细胞表达MCP-1 mRNA和蛋白，在用COM和OX处理后，其表达水平以时间和浓度依赖性方式显著增加。暴露于COM后，MCP-1 mRNA表达和蛋白产生的增加比暴露于OX后更显著。用过氧化氢酶（2000 U/mL）处理后，这些反应显著降低。
NRK52E细胞表达MCP-1 mRNA和蛋白，在暴露于COM和OX后其水平会发生改变。由于过氧化氢酶处理降低了MCP-1表达，自由基可能参与上皮细胞中MCP-1产生的上调。结果表明，MCP-1表达的升高通常与局部炎症反应相关，可能介导类似反应，包括在肾结石形成早期间质晶体周围巨噬细胞的吸引。
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