A multi-system approach to analyze the role of enniatins and their association with deoxynivalenol in plants, microorganisms, insects, animals and humans.

Enniatins (ENNs) and deoxynivalenol (DON) are among the most prevalent fungal secondary metabolites found in wheat grains worldwide. The main fungal species responsible for their production, Fusarium avenaceum (FA) for ENNs and Fusarium graminearum (FG) for DON, are also globally distributed. This project aimed to understand the role of ENNs and their association with DON in plants, microorganisms, insects, animals, and humans. In common wheat, DON and enniatin B (ENB, one of the most common ENN analogues) decreased germination and growth, particularly when combined. DON also mitigated ENB-induced cell death. While DON was confirmed as a virulence factor, ENNs exhibited limited promotion of the initial infection phases in the spike. Other results suggest a potential role for ENB in defense priming, triggering wheat immune response genes. In Fusarium species, the main growth inhibition was observed at 100 mg/L of DON+ENB combination. Only FG and FA showed a reduction in growth starting at 10 mg/L of DON+ENB. Gene expression analysis of FG grown in the presence of 100 mg/L of DON and ENB, individually or combined, indicated stress induction. In vitro and in vivo studies suggested that DON and ENNs did not play a significant role in interspecific competition among Fusarium species. Microbiome studies showed that ENB had no significant impact on biocontrol agents’ growth and activity, including secondary metabolite production, even at the highest concentration (100 μg/mL). Wheat spike microbial communities were unaffected by 1000 μg/kg ENB, with no colony count difference compared to the control. The wheat spike's micro/mycobiome was slightly influenced by ENB and ENB+DON. Exposure of the English grain aphid, Sitobion avenae, to DON (100 mg/L) or DON+ENB (100 mg/L) increased mortality, whereas ENB alone had no effect. DON-treated aphids showed a dosedependent increase in mortality over 48 to 96 hours. The larvae of the aphid predator Chrysoperla carnea showed no change in mortality when exposed to water-dissolved secondary metabolites but exhibited increased mortality with acetone-solubilized DON+ENB. Indirect exposure through prey had no effect. In bovine, 5 to 10 μM of ENB reduced polymorphonuclear leukocyte (PMN) phagocytosis of Escherichia coli and Staphylococcus aureus and extracellular reactive oxygen species production under pro-inflammatory in vitro conditions, potentially impairing PMN antimicrobial activity and immune response. ENB (2.7 mg/day) had no major effects on cow performance or metabolism, with only minor effects on fecal microbiota. In human studies, apical exposure of intestinal epithelial CaCo2 cells to DON, ENB, and their combination did not compromise barrier integrity. DON increased IL-8 expression and basolateral secretion and triggered p38 MAPK-mediated inflammasome activation in monocytic THP-1 cells in the basolateral compartment, suggesting that mycotoxin-induced changes in gut epithelial cells may contribute to local immune cell inflammation.