Molecular mechanism of the combined exposure to AFB1 and DON in promoting the functional and phenotypic remodeling of porcine alveolar macrophages

Aflatoxin B1 (AFB1) and deoxynivalenol (DON) often coexist and exhibit immunotoxicity. Recent studies have reported that AFB1 and DON exposure alone not only promoted immunosuppression, but also induced inflammation, demonstrating as bidirectional immunotoxicity. Nevertheless, whether the combination of AFB1 and DON exhibit bidirectional immunotoxicity and their mechanism remain unclear. Here, porcine alveolar macrophages were used as an in vitro model, and quantitative Real-Time PCR (qRT-PCR), Western blotting (WB), flow cytometry, network toxicology and molecular docking were used to investigate the bidirectional immunotoxicity and mechanism of AFB1 and DON combined contamination. Our results showed that the combined exposure of low concentrations of AFB1 and DON (0.005 + 0.5 μg/mL) induced macrophages polarizing to immunostimulatory M1 by upregulating the TLR4-NF-κB, while the combined exposure of high concentrations of AFB1 and DON (0.04 + 4 μg/mL) promoted macrophages polarizing to immunosuppressive M2 by downregulating the PI3K-AKT. The results will provide new insights for the in-depth study of the pathogenic mechanism of AFB1 and DON combined contamination.

Aflatoxin B1; Deoxynivalenol; Immunostimulation; Immunosuppression; PI3K-AKT; TLR4-NF-κB.