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.

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.

Individual and combined effects of Fusarium toxins on the mRNA expression of pro-inflammatory cytokines in swine jejunal epithelial cells.

Fusarium toxins have been arousing public interest in recent years because of their potential health hazards for humans and agricultural livestock. It was hypothesized that selected pro-inflammatory cytokines might serve as sensitive biomarkers of the predicted adverse effects of Fusarium toxins on the basis of their potential ability to induce immune and intestinal alterations comparable to those in human chronic inflammatory infection. Consequently, the aim of this study was to elucidate individual and combined effects of four common Fusarium toxins, deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and fumonisin B1 (FB1) on the mRNA expression of pro-inflammatory cytokines (IL1α, IL1ß, IL6, IL8, TNFα and MCP-1) using a porcine jejunal epithelial cell line, IPEC-J2. Based on a dose-response relationship between individual mycotoxins and cell viability (MTT assay) that was previously established, cytotoxic and non-cytotoxic concentrations were selected to investigate combinations of two, three and all four of the mycotoxins. In general, up-regulation of pro-inflammatory cytokine mRNA expression occurred for both individual and mixtures of Fusarium toxins at cytotoxic concentrations, whereas significant up-regulation of pro-inflammatory cytokine mRNA mostly obtained when the toxins existed in mixtures at non-cytotoxic concentrations and these mixtures were found to cause cytotoxicity from MTT assay determined previously. Therefore, it may be concluded that some of the changes in the mRNA expression of IL1α, IL1ß, IL6, IL8, TNFα and MCP-1 could be cytotoxicity-related. It was also noted that additive effects were not always observed for the mixtures. These data suggest that individual or mixtures of Fusarium toxins could cause or exacerbate intestinal inflammation. These also provide a better understanding of the possible effects of Fusarium toxins, alone or in combinations on the immunological defense mechanisms of IECs, which would contribute to the risk assessment of these toxins.

Individual and combined cytotoxic effects of Fusarium toxins (deoxynivalenol, nivalenol, zearalenone and fumonisins B1) on swine jejunal epithelial cells.

Fusarium mycotoxins occur worldwide in foods such as cereals and animal forages, leading to acute and chronic exposures in human and animals. Intestinal epithelial cells (IECs) are an important first target site for these dietary toxins. This study investigated the cytotoxicity of four common Fusarium mycotoxins, deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and fumonisin B1 (FB1) on a normal porcine jejunal epithelial cell line, IPEC-J2. A dose response relationship between individual mycotoxins and cell viability (MTT assay) was initially investigated, and subsequently cytotoxic and non-cytotoxic concentrations were selected to investigate combinations of two, three and all four of the mycotoxins. For individual mycotoxins, a dose response was observed with cell viability, such that the potency ranking was NIV>DON>ZEA>FB1. At cytotoxic doses of individual mycotoxins, all mixtures gave reduced cell viability compared to control. At noncytotoxic concentrations of individual mycotoxins, all mixtures were cytotoxic with DON-NIV, DON-ZEA, DON-NIV-FB1, DON-ZEA-FB1, NIV-ZEA-FB1 and all four mixed causing the greatest loss of cell viability. The latter observation in particular raises concerns over safety margins based on single toxin species, and suggests that the effects of multiple complex mixtures need to be better understood to assess health risks.