Regulatory effects of dandelion flavonoids in LPS-induced immune stress in broilers

This study investigated the protective effect of dandelion flavonoids (DF) against lipopolysaccharide (LPS)-induced immune stress in broilers. A total of 400 healthy one-day-old Cobb 500 broilers with similar body weight were randomly assigned to five groups, with 8 replicates per group and 10 broilers per replicate. The treatments included CON, LPS, DF200, DF300 and DF400. The CON and LPS groups received a basic diet, while the DF200, DF300, and DF400 groups received 200, 300 and 400 mg/kg dietary DF, respectively. One bird per replicate was randomly selected. Broilers in the LPS and DF groups were injected intraperitoneally with 1 mg/kg body weight LPS in saline at 38, 40, and 42 days of age, while the CON group received saline alone. The results showed that compared with the LPS group, dietary DF significantly reduced spleen and liver indices (P < 0.05) and enhanced serum levels of IgA, IgG and IgM (P < 0.05). Dietary DF decreased the content of TNF-α and IL-1β (P < 0.05), while increased the IL-10 content (P < 0.05). Dietary DF enhanced the relative abundance of Bacteroidetes and Bacteroides, while reduced Firmicutes and the ratio of Firmicutes and Bacteroidetes (P < 0.05). Metabolomic analysis revealed 19 differential metabolites, among which DF notably reduced the levels of four harmful biomarker compounds including 7alpha-Hydroxy-3-oxo-4-cholestenoate, 11-deoxycortisol, taurocholic acid and triethanolamine (P < 0.05). Spearman's correlation analysis revealed that 11-deoxycortisol, taurocholic acid and triethanolamine were positively correlated with IL-1β (P < 0.05) and TNF-α (P < 0.01). The 11-deoxycortisol and taurocholic acid were negatively correlated with IL-10 (P < 0.01). The taurocholic acid (P < 0.05) and triethanolamine (P < 0.01) were negatively correlated with IgM. The Bacteroides positively correlated with IgG (P < 0.01) and IL-10 (P < 0.05), and negatively correlated with TNF-α (P < 0.01) and 7α-Hydroxy-3-oxo-4-cholestenoate (P < 0.05). The 7α-Hydroxy-3-oxo-4-cholestenoate was positively associated with increased TNF-α (P < 0.01). In summary, the DF may reduce immune stress by modulating cecal microbiota and harmful metabolites.