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Human Proximal Tubule Epithelial Cells (HK-2) as a Sensitive In Vitro System for Ochratoxin A Induced Oxidative
Enrique García-Pérez1, Dojin Ryu2, Hwa-Young Kim3
1School of Food Science, Washington State University, P.O. Box 646376, Pullman, Washington, DC 99164-6376, USA.
Abstract:
Ochratoxin A (OTA) is a mycotoxin that is potentially carcinogenic to humans. Although its mechanism remains unclear, oxidative stress has been recognized as a plausible cause for the potent renal carcinogenicity observed in experimental animals. The effect of OTA on oxidative stress parameters in two cell lines of LLC-PK1 and HK-2 derived from the kidneys of pig and human, respectively, were investigated and compared. We found that the cytotoxicity of OTA on LLC-PK1 and HK-2 cells was dose- and time-dependent in both cell lines. Furthermore, increased intracellular reactive oxygen species (ROS) induced by OTA in both cell lines were observed in a time-dependent manner. Glutathione (GSH) was depleted by OTA at >48 h in HK-2 but not in LLC-PK1 cells. While the mRNA levels of glucose-6-phosphate dehydrogenase (G6PD) and glutathione peroxidase 1 (GPX1) in LLC-PK1 were down-regulated by 0.67- and 0.66-fold, respectively, those of catalase (CAT), glutathione reductase (GSR), and superoxide dismutase 1 (SOD) in HK-2 were up-regulated by 2.20-, 2.24-, and 2.75-fold, respectively, after 72 h exposure to OTA. Based on these results, we conclude that HK-2 cells are more sensitive to OTA-mediated toxicity than LLC-PK1, and OTA can cause a significant oxidative stress in HK-2 as indicated by changes in the parameter evaluated.
Insights
Ochratoxin A (OTA) causes kidney cell damage via oxidative stress. Human kidney cells (HK-2) are more sensitive to OTA toxicity than pig kidney cells (LLC-PK1), showing significant changes in oxidative stress markers.
Area of Science:
- Toxicology
- Cell Biology
- Molecular Biology
Background:
- Ochratoxin A (OTA) is a mycotoxin with potential human carcinogenicity, particularly affecting the kidneys.
- Oxidative stress is a suspected mechanism underlying OTA's renal carcinogenicity in animal models.
- Understanding OTA's cellular effects on oxidative stress is crucial for assessing human health risks.
Purpose of the Study:
- To investigate and compare the effects of Ochratoxin A (OTA) on oxidative stress parameters in human (HK-2) and pig (LLC-PK1) kidney cell lines.
- To determine the dose- and time-dependent cytotoxicity of OTA in these cell lines.
- To elucidate the cellular mechanisms of OTA-induced oxidative stress.
Main Methods:
- Exposure of LLC-PK1 and HK-2 cells to varying concentrations of OTA over different time periods.
- Assessment of cell viability and cytotoxicity.
- Measurement of intracellular reactive oxygen species (ROS) levels.
- Quantification of glutathione (GSH) levels.
- Analysis of mRNA expression for key oxidative stress-related enzymes (G6PD, GPX1, CAT, GSR, SOD).
Main Results:
- OTA exhibited dose- and time-dependent cytotoxicity in both LLC-PK1 and HK-2 cells.
- Increased intracellular ROS was observed in both cell lines following OTA exposure.
- Glutathione (GSH) depletion occurred in HK-2 cells after 48 hours but not in LLC-PK1 cells.
- Significant differential regulation of antioxidant enzyme mRNA levels was observed: G6PD and GPX1 were downregulated in LLC-PK1, while CAT, GSR, and SOD were upregulated in HK-2 cells after 72 hours of OTA exposure.
Conclusions:
- Human kidney HK-2 cells are more susceptible to Ochratoxin A (OTA)-induced toxicity than pig kidney LLC-PK1 cells.
- OTA induces significant oxidative stress in HK-2 cells, evidenced by increased ROS and altered antioxidant enzyme expression.
- These findings highlight the differential cellular responses to OTA and provide insights into its nephrotoxic mechanisms.
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