engleski

Effects of the micotoxin ochratoxin A on the green monkey cell line CV-1

Mycotoxins are a large group of naturally occurring toxins. Some of them are highly toxic substances, expressing their toxicity on various organs and cells in human and animal organisms. There have been some attempts to use mycotoxins for military purposes, alone or in combination with classical chemical agents. For nephrotoxic mycotoxin ochratoxin A (OTA), as well as for a number of other mycotoxins, the mode of their toxic activity is still not known. To study adverse effects of OTA on cellular level, Green monkey kidney cell line CV-1 were cultivated and exposed to OTA. Cell cultures were exposed to OTA dissolved in dimethyl sulfoxide, in concentrations range 0.004 - 400 μ M over 24, 48 and 72 hours, respectively. Metabolic activity was measured by using thiazolyl-tetrazolium bromide mitochondrial dehydrogenase activity test (MTT). In all treatment periods the lowest concentration of OTA which resulted in cell viability inhibition was found to be 4 μ M OTA. In treatment period of 24h at OTA concentration 20 μ M remaining cell metabolic activity was found to be 45.1 % in comparison with untreated control group (100 % metabolic activity). The same OTA concentration over longer time period resulted in higher inhibition of metabolic activity, leaving only 35.8 % and 18.2 % activity after 48 and 72h, respectively. Thus differences in activity may be explained by higher percentage of death cells after longer treatment period and consequently smaller metabolic activity that can be measured by use of MTT test. The IC50 value after treatment period of 24 hour was 18.7 μ M OTA. In OTA-positive samples of human sera obtained from people living in the area where fatal human kidney disease called Endemic Nephropathy in Croatia is present, OTA concentrations varied between 2 and 50 ng/ml (4.96 and 124 μ M) OTA (1). Toxicokinetics studies using monkey as an animal model, and the calculations based on available data from humans naturally exposed to OTA have shown that the toxin in those species is predominantly eliminated by renal filtration (2). Our in vitro results strongly suggest that concentrations found in the human blood by natural exposure to the OTA can cause severe damage of kidney cells in vivo. It is known that cells exposed to cytotoxic drugs are undergoing necrotic or apoptotic processes. Which of those processes will be expressed is very much related to mode of action of the cytotoxic substance as such. Based on our results and the data from the published literature, it seems that cytotoxicity of OTA is connected with induction of apoptosis rather then necroses.

ochratoxin A; kidney desease; cytotoxicity; apoptosis

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