Curcumin: a potential exogenous additive for the prevention of LPS‐induced duck ileitis by the alleviation of inflammation and oxidative stress

Lipopolysaccharides (LPS) are the main pathogenic substances in Gram-negative bacteria. The aim of this study was to investigate the preventive effects of dietary curcumin (CUR) on LPS toxicity in the duck ileum. The duck diet was supplemented with CUR (0.5 g kg-1 ) for 28 days, while the birds were injected with LPS (0.5 mg kg-1 body weight per injection, administered as seven injections in the last week of the experimental period).LPS significantly decreased the ileal villus-to-crypt ratio in the non-supplemented CUR group. Dietary CUR alleviated LPS-induced morphological damage to the ileum. Moreover, dietary CUR alleviated oxidative stress by increasing the levels of total superoxide dismutase (T-SOD) (P < 0.05) and glutathione S-transferase (GST) (P < 0.05) and decreasing the production of malonic dialdehyde (MDA) (P < 0.05) in control ducks and LPS-challenged ducks. Dietary CUR significantly inhibited the LPS-induced massive production of inflammatory factors (IL-1β, IL-6, and TNF-α) (P < 0.05). CUR induced the inhibition of TLR4 and activation of Nrf2 to reduce the expression of inflammation-related genes (TLR4, NF-κB, IKK, TXNIP, NLRP3, caspase-1, IL-1β, IL-6, and TNF-α). Moreover, dietary CUR ameliorated the decrease in claudin-1 and occludin expression (P < 0.05) and improved ZO-1 expression in the duck ileum (P < 0.05).In conclusion, dietary CUR has beneficial effects on LPS-induced ileal damage, oxidative damage, and inflammatory response by inhibiting the TLR/NF-κB and activating the Nrf2 signaling pathways in ducks. This study provides valuable information regarding the therapeutic uses of CUR in duck ileitis. © 2022 Society of Chemical Industry.