Curcumin attenuates liver inflammation in ducks fed corn contaminated with ochratoxin A possibly by regulating intestinal microbiota and inhibiting toll like receptor 4/nuclear factor kappa-B signaling pathway

Curcumin (CUR) has been well known for its anti-inflammatory effects, and could regulate the intestinal mi-crobial composition, and alleviate mycotoxin toxicity. The present study was conducted to explore whether curcumin could alleviate ochratoxin A (OTA)-induced liver inflammation. A total of 720 mixed-sex 1-D-old White Pekin ducklings were randomly assigned to 4 groups: CON (control group, without OTA), OTA (fed 2mg/kg OTA-contaminated diet), CUR (ducks fed a diet with 400mg/kg curcumin), and OTA + CUR (fed the same OTA-contaminated diet plus 400mg/kg curcumin). Each treatment consisted of 6 replicates, each containing 30 ducklings, and treatment lasted for 21 d The results demonstrated that OTA treatment increased the liver interleukin-1beta (P < 0.001) and interleukin-6 (IL-6) contents (P=0.047). Curcumin supplementation alleviated OTA-induced the liver IL-6 content (P < 0.001). Metagenomic sequencing analysis indicated that a clear sepa-ration between the cecum microbiota of ducks in CON and OTA treatment. Compared with CON treatment, ochratoxin A increased the relative abundance of Bacteroides (P < 0.05). The OTA treatment increased pathway expression associated with inflammation and exposure to oxidative stress, including lipopolysaccharide (LPS) biosynthesis (P=0.002) and tricarboxylic acid cycle (P=0.006). Curcumin could alleviate the upregulation of inflammation and oxidative stress pathways induced by OTA (P < 0.01). Compared with CON, OTA treatment increased serum LPS content (P < 0.001). Compared with OTA treatment, OTA + CUR treatment decreased serum LPS content (P < 0.001). Compared with the CON treatment, OTA treatment upregulated the relative mRNA expression of toll like receptor 4 (TLR4) (P=0.05) and tumor necrosis factor-alpha (P=0.028) and upregulated the expression of myeloid differentiation factor 88 (P=0.001) and IL-6 (P=0.002). Compared with the OTA treatment, OTA + CUR treatment decreased the expression of TLR4 (P=0.05). The curcumin treatment had the lowest expression rate of TLR4 mRNA (P < 0.05). The results indicated that curcumin could alleviate OTA-induced inflammation by regulating the intestinal microbiota. Furthermore, the protective role of curcumin in OTA-exposed ducks possibly inhibited TLR4 signaling pathway.