Modulation of mucin mRNA (MUC5AC and MUC5B) expression and protein production and secretion in Caco-2/HT29-MTX co-cultures following exposure to individual and combined Fusarium mycotoxins.

Abstract

Intestinal epithelial cells (IECs) are a critical component of the innate local immune response. In order to reduce the risk of pathogen infection or xenobiotic intoxication, different host defense mechanisms have been evolved. Evidence has shown that upon ingestion of food or feed contaminated with toxins (e.g., mycotoxins), IECs respond by regulating mucin secretions, which act as a physical barrier inhibiting bacterial attachment and subsequent infection-related processes. However, the effect of Fusarium mycotoxins on mucin production remains unclear. Consequently, the aim of this study was to evaluate individual and interactive effects of four common Fusarium mycotoxins, deoxynivalenol, nivalenol, zearalenone, and fumonisins B1 on mRNA expression and secretion of mucins, MUC5AC, and MUC5B, as well as total mucin-like glycoprotein secretion, using Caco-2 (absorptive-type) and HT29-MTX (secretive-type) cells and their co-cultures (initial seeding ratios Caco-2/HT29-MTX: 90/10 and 70/30). Our results showed that individual and mixtures of mycotoxins significantly modulated MUC5AC and MUC5B mRNA and protein, and total mucin-like glycoprotein secretion as measured by quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and enzyme-linked lectin assay, respectively. Additive effects were not always observed for mixtures. Also, the present study showed that in co-cultures, lower MUC5AC and MUC5B mRNA, protein and total mucin production occurred following exposure, which might suggest higher intestinal permeability and susceptibility to toxin exposure. This study demonstrates the importance of selecting an appropriate cell model for the in vitro investigation of Fusarium mycotoxin effects either alone or in combinations on the immunological defense mechanisms of IECs, and will contribute to improved toxin risk assessments.