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S. J. Upadhyay, J. A. Hossain, C. Leeuwenburgh, S. Kaushal; Heat Shock Mitigates Sodium Iodate-Mediated RPE Cell Death. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5559.
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To understand the effect of the heat shock response (hsr) in RPE cells exposed to sodium iodate.
ARPE-19 cells were cultured by standard previously described methods. Sodium iodate was added to cells at various concentrations. At various times afterwards, cells were harvested and viability was determined using a cellometer after trypan blue staining. An experimentally convenient dose (10 mM) was established and used in all subsequent studies. This dose is nearly equivalent to the amount given to mice that results in RPE cell death in previously reported studies. ARPE-19 cells were pre-incubated with various concentration of celastrol, a known chemical inducer of the hsr. Thereafter, ARPE-19 cells were exposed to 10 mM sodium iodate and at various times post-insult the number of viable cells was quantitated. Immunofluorescence microscopy was performed after annexin V staining of cells.
We first studied the dose and time-dependent nature of RPE cell death in the presence of sodium iodate. At 1 mM concentration there was no significant cell death at all time points including 24, 48, 72 hrs post-injury. At 10 and 100 mM concentrations, there was statistically significant cell death at all time points with greater cell death in the RPE cells incubated with 100 mM iodate. In the 10 mM iodate injured cells where heat shock was induced, there was a statistically significant reduction in cell death. Analysis of iodated exposed cells treated with the placebo (DMSO) showed profound morphological changes associated with apoptosis- including nuclear fragmentation, blebbing and annexin V staining Additionally, IF revealed that the celastrol-treated cells in either the absence or presence of iodate showed minimal apoptotic features.
For the first time, we demonstrate that in a dose-dependent manner sodium iodate can induce cell death of ARPE-19 cell lines. This effect appears to have characteristics of apoptosis and can be limited by the hsr. This model system can be examined to understand the mechanism of RPE cell death and correlate those observations with in vivo mouse studies using sodium iodate.
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