Toxicity of the mycotoxin patulin for rat alveolar macrophages

Agricultural workers are exposed to a variety of organic dusts containing fungi and their secondary metabolites. Patulin, a polyketide lactone mycotoxin produced by several common species of Aspergillus and Penicillium, is found in corn silage. Patulin is toxic in experimental animals and has been reported to be mutagenic, teratogenic, and carcinogenic. The cytotoxicity of patulin was studied in rat alveolar macrophages in vitro. The effects of patulin on membrane integrity were studied by measuring cell volume changes and release of 51Cr. There was a significant release of 51Cr after 1 hr exposure to submillimolar concentrations of patulin. Similarly, there was a significant decrease in ATP in cell cultures exposed to 0.5 mM patulin for 15 min and in cultures exposed to 0.05 mM patulin for 2 hr. There was a significant increase in mean cell volume after 2 hr exposure to 1.0 mM patulin but not after a 1 hr exposure. The effects of patulin on protein and RNA synthesis were studied by monitoring the incorporation of [3H]leucine and [3H]uridine, respectively. Inhibitions of protein and of RNA synthesis were both dose and time dependent. Protein synthesis was the most sensitive cellular parameter studied, with 50% inhibition after 1 hr at ca. 0.002 mM patulin. The data demonstrate that patulin is cytotoxic for rat alveolar macrophages in vitro.