Selenium and Taurine Combination Is Better Than Alone in Protecting Lipopolysaccharide-Induced Mammary Inflammatory Lesions via Activating PI3K/Akt/mTOR Signaling Pathway by Scavenging Intracellular ROS.

Mastitis is mainly induced by gram-negative bacterial infections, causing devastating economic losses to the global cattle industry. Both selenium (Se) and taurine (Tau) exhibit multiple biological effects, including reducing inflammation. However, no studies have reported the protective effect of the combined use of Se and Tau against mastitis, and the underlying mechanisms remain unclear. In this study, lipopolysaccharide (LPS), the vital virulence factor of gram-negative bacteria, was used to construct the in vivo and vitro mastitis models. The results of in vivo model showed that Se and Tau combination was more effective than either substance alone in reducing tissue hyperemia, edema, and neutrophil infiltration in the mammary acinar cavity, improving the blood-milk barrier in LPS-induced mice mastitis, and decreasing the expression of proinflammatory factors and the activity of MPO. Moreover, Se and Tau combination significantly increased the levels of LPS-induced reduction in PI3K/Akt/mTOR, but the expressions of TLRs and NLRP3 were not significantly changed in the mammary tissue. In the in vitro experiments, the effects of Se and Tau combination or alone on inflammatory factors, inflammatory mediators, MPO activity, and blood-milk barrier were consistent with those in vivo. The Se and Tau combination has also been found to increase the survival rate of BMECs compared with each substance alone via promoting cellular proliferation and inhibiting apoptosis. Also, it has been confirmed that this combination could restore the LPS-induced inhibition in the PI3K/Akt/mTOR signaling pathway. Inhibition of mTOR by Rapamycin counteracted the combined protection of SeMet and Tau against LPS-induced inflammatory damage, the inhibition of PI3K by LY294002 blocked the activation of mTOR, and the accumulation of ROS by the ROS agonist blocked the activation of PI3K. In conclusion, these findings suggested that Se and Tau combination was better than either substance alone in protecting LPS-induced mammary inflammatory lesions by upregulating the PI3K/Akt/mTOR signaling pathway.

Activation of AMPK-dependent SIRT-1 by astragalus polysaccharide protects against ochratoxin A-induced immune stress in vitro and in vivo.

Recent studies have highlighted the immune stress caused by ochratoxin A (OTA), but little attention was paid to its alleviation. In the present study, the protective effects of astragalus polysaccharide (APS) against OTA-induced immune stress in vitro and in vivo and its mechanism/(s) involved were investigated. The in vitro results showed that APS (20 µg/ml) induced a significant decrease in cytotoxicity, apoptosis and pro-inflammatory cytokine expressions elevated by OTA (1.5 µg/ml) in porcine alveolar macrophages (PAMs). In vivo, APS (200 mg/kg b.w.) significantly alleviated OTA-induced (75 µg/kg b.w.) spleen damages and decreased the expressions of OTA-promoted apoptosis-related protein and pro-inflammatory cytokine. Further study indicated that APS caused significant enhancement of AMPK/SIRT-1 and inhibition of NFκB in PAMs and mice. The down-regulation of SIRT-1 by EX527 in vivo or EX527 and SIRT-1 knockdown in vitro abolished the inhibitory effects of APS on OTA-induced cytotoxicity, apoptosis, spleen damages and pro-inflammatory cytokine expressions. Taken together, these findings indicate that APS could attenuate the immune stress induced by OTA in vitro and in vivo via activation of the AMPK/SIRT-1 signaling pathway.