Oxalate induced expression of monocyte chemoattractant protein-1 (MCP-1) in HK-2 cells involves reactive oxygen species

Oxalate is a toxic end product of metabolism largely because of its propensity to crystallize and form calcium oxalate, which is insoluble at physiologic pH and often deposits at very unfortunate sites, notably the kidneys. In the current study, we investigated the oxalate-induced injury and up-regulation of monocyte-chemoattractant protein-1 (MCP-1) in HK-2 cells, a proximal tubular epithelial cell line derived from normal human kidney. The cells were exposed to oxalate ions for different lengths of time. The culture media was tested for LDH release, a cell injury marker. mRNA was isolated from the cells and subjected to reverse transcriptase-polymerase chain reaction. The data showed that oxalate exposure resulted in cell injury in a time and concentration dependent manner. The MCP-1 mRNA increased following exposure to oxalate and was reduced upon treatment with free radical scavengers, catalase and superoxide dismutase. These data support the importance of reactive oxygen species in the induction of expression of MCP-1 in renal epithelial cells. To our knowledge, this is the first report of MCP-1 expression and its upregulation by oxalate exposure in HK-2 cells.