Oxalate stimulates IL-6 production in HK-2 cells, a line of human renal proximal tubular epithelial cells
Oxalate stimulates IL-6 production in HK-2 cells, a line of human renal proximal tubular epithelial cells
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DOI：
10.1111/j.1523-1755.2005.00427.x
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发表时间：
2005-08-01
影响因子：
19.6
通讯作者：
Koul, HK
中科院分区：
文献类型：
--
作者：
Huang, MY;Chaturvedi, LS;Koul, HK
背景。草酸盐是一种主要由肾脏排泄的代谢终产物，与多种病理状况相关。涉及草酸盐的最常见病理状况是肾脏中草酸钙结石的形成。在各种形式的免疫介导的肾脏疾病中，肾小球和肾小管损伤的发展与多种刺激因素有关。据报道，肾结石形成患者的尿液中白细胞介素 - 6（IL - 6）水平升高。在本研究中，我们研究了草酸盐（草酸钙肾结石疾病的主要成分）在正常人HK - 2肾细胞中产生IL - 6的作用。
方法。在无血清条件下，将HK - 2细胞（一种人源性肾上皮细胞系）的融合培养物暴露于不同浓度的草酸盐（0.2至2.0 mmol/L）和脂多糖（LPS）（0.1和10μg/mL）不同时间点（4 - 24小时）。收集条件培养基，通过酶联免疫吸附测定（ELISA）测量IL - 6蛋白水平。从细胞中分离总细胞RNA，并进行相对定量逆转录 - 聚合酶链反应（RT - PCR）以确定IL - 6 mRNA的表达。使用学生t检验对结果进行统计分析。
结果。HK - 2细胞表达IL - 6 mRNA和蛋白。草酸盐以浓度依赖的方式增加HK - 2细胞中IL - 6蛋白的分泌。草酸盐暴露于HK - 2细胞也诱导了IL - 6基因的转录上调，这通过草酸盐处理后IL - 6 mRNA表达水平的增加来确定。此外，草酸盐对IL - 6表达的影响具有时间和浓度依赖性。这是首次报道草酸盐对IL - 6的调节作用。
结论。本研究提供了第一个直接证据，表明草酸盐上调肾上皮细胞中IL - 6的表达和分泌。肾上皮细胞中IL - 6表达和分泌的增加可能在高草酸尿症情况下尿石症的进展中起关键作用。
Background. Oxalate is a metabolic end product excreted primarily by the kidney and associated with several pathologic conditions. The most common pathologic condition involving oxalate is the formation of calcium oxalate stones in the kidney. Several stimuli have been implicated in the development of glomerular and tubular injury in various forms of immune-mediated renal diseases. The elevated level of interleukin-6 (IL- 6) has been reported in the urine of kidney stone-forming patients. In the present study, we investigated the role of oxalate, a major constituent of calcium oxalate kidney stone disease, in the production of IL- 6 in normal human HK-2 kidney cells.Methods. Confluent cultures of HK-2 cells ( a renal epithelial cell line of human origin) were exposed to various concentrations of oxalate (0.2 to 2.0 mmol/ L) and lipopolysaccharide (LPS) (0.1 and 10 mu g/mL) for various time points (4-24 h) under serum-free conditions. The conditioned mediums were collected, and an IL- 6 protein level was measured by enzyme-linked immunosorbent assay (ELISA). The total cellular RNA was isolated from the cells and subjected to relative quantitative reverse transcription-polymerase chain reaction (RT-PCR) to determine the expression of IL- 6 mRNA. The statistical analysis of the results was carried out using the Student t test.Results. HK-2 cells express IL- 6 mRNA and protein. Oxalate increased the secretion of IL- 6 protein in HK-2 cells in a concentration-dependent fashion. Oxalate exposure to HK-2 cells also induced transcriptional up-regulation of the IL- 6 gene, as determined by the increased level of IL- 6 mRNA expression following treatment with oxalate. Moreover, the effects of oxalate on IL- 6 expression were time- and concentration-dependent. This is the first report demonstrating the regulation of IL-6 by oxalate.Conclusion. This study provides the first direct evidence that oxalate up-regulates the expression and secretion of IL-6 in renal epithelial cells. The increased IL-6 expression and secretion by renal epithelial cells may play a critical role in the progression of urolithiasis in hyperoxaluric conditions.