Mechanism-based alternative monitoring of endoplasmic reticulum stress by 8-keto-trichothecene mycotoxins using human intestinal epithelial cell line

Abstract

Type B 8-keto trichothecenes are muco-active mycotoxins that are notable contaminants in cereal-based food stuffs. Epithelial responses are of primary concern during gastrointestinal exposure in human and animal intoxications. Therefore, optimized biomarkers to assess the specific action of trichothecenes on the human epithelial barrier are needed. In the present study, 8-keto trichothecenes were tested to trigger endoplasmic reticulum (ER) stresses that are evident as alteration of eukaryotic initiation factors 2α phosphorylation and other ER stress markers in human intestinal epithelial cells. Based on the ER stress-inducing activity of 8-keto trichothecenes, we developed a bio-monitoring method using intestinal epithelial cells constitutively expressing secretory alkaline phosphatase (SEAP) reporter, which can be used as a sensitive and selective indicator for monitoring ER stress in the epithelial barrier. Type B 8-keto trichothecenes suppressed the release of SEAP in a dose-dependent manner, showing a negative correlation between logarithm of toxin dose and SEAP activity. However, tested toxins did not affect SEAP enzymatic activity and mRNA levels, but reduced the cellular release of SEAP. Moreover, in order to correct the monitoring of 8-keto trichothecene in crop matrix, the bioassay was proven to work in standard cereal extract of corn and rice. The mechanism-based monitoring of 8-keto trichothecenes is promising as a supplementary analysis means of the presence of bioactive 8-keto trichothecenes, which are potentially exposed in human gut epithelia.