Mannan Oligosaccharide Could Attenuate Ochratoxin A-Induced Immunosuppression with Long-Time Exposure Instead of Immunostimulation with Short-Time Exposure

Our previous study showed that ochratoxin A (OTA), one of the most common mycotoxins in feed, could induce immunosuppression with long-time exposure but immunostimulation with short-time exposure. However, limited studies for the control of OTA-induced two-way immune toxicity were carried out. This study explored the effects of mannan oligosaccharide (MOS), a glucomannoprotein complex with immunoregulatory capability derived from the yeast cell wall, on OTA-induced immune toxicity and its underlying mechanisms. Surprisingly, the results showed that MOS significantly attenuated immunosuppression induced by long-time OTA treatment but did not provide protection against immunostimulation induced by short-time OTA treatment on porcine alveolar macrophages (PAMs), as demonstrated by the expressions of inflammatory cytokines and the capability of migration and phagocytosis. Further, MOS increased the OTA-inhibited autophagy level and the JNK phosphorylation level on PAMs with long-time OTA treatment. In addition, the inhibition of autophagy by 3-MA or the inhibition of JNK phosphorylation by SP600125 could partly block the protective effects of MOS on OTA-induced immunosuppression. Importantly, the inhibition of JNK phosphorylation down-regulated the MOS-promoted autophagy level. In conclusion, MOS could attenuate OTA-induced immunosuppression with short-time exposure on PAMs through activating JNK-mediated autophagy but had no significant effects on OTA-induced immunostimulation with short-time exposure. Our study provides new insights into the application of MOS as an immunoregulator against mycotoxin-induced immune toxicity.