Enniatin B alters bovine polymorphonuclear leukocytes phagocytosis and extracellular reactive oxygen species production in vitro

Enniatins (ENNs) affect human and animal health. Different ENN analogs have been identified, but Enniatin B (ENN B) is the most detected in foods and feeds. This study investigated the effect of ENN B on bovine polymorphonuclear leukocytes (PMNs) challenged with increasing ENN B concentrations (0.625, 1.25, 2.5, 5, and 10 μM). Bovine PMNs were isolated from the peripheral blood of dairy cows to evaluate the cell viability, chemotactic function, ability to phagocyte Gram+ and Gram– microorganisms, and extracellular Reactive Oxygens Species (ROS), with or without phorbol 12-myristate-13-acetate (PMA) as a pro-inflammatory challenge. Results demonstrated that ENN B did not affect bovine PMN viability and chemotactic activity at all concentrations (p = 0.952; p = 0.218, respectively). E. coli and S. aureus phagocytosis ability were reduced by ENN B at the highest concentrations (5 and 10 μM) compared to the negative control (p ≤ 0.001; p = 0.001, respectively). Extracellular ROS production was increased by ENN B challenge under physiological and pro-inflammatory conditions (p = 0.014; p < 0.001, respectively). In conclusion, ENN B did not exert cytotoxic effects on bovine PMNs, while reduced phagocytic ability and increased the production of extracellular ROS, highlighting its potential role as an immunomodulator of the bovine innate immune response in vitro. Implications: Emerging mycotoxin Enniatin B is a common grain contaminant worldwide that can exert cytotoxic and immunotoxic effects in animal cells. We hypothesized that Enniatin B could in vitro affect the bovine immune response. In our study, Enniatin B did not affect bovine polymorphonuclear cell viability and chemotaxis, while a reduction of phagocytosis and a modulation of extracellular reactive oxygen species were observed. The present study shows that Enniatin B in vitro exerts a potential role as an immunomodulator of the bovine innate immune response putting animals at an increased risk of infection diseases.