Curcumin alleviates broiler liver damage caused by polybrominated diphenyl ether concurrent with restoring gut microbiota, reducing liver inflammation and endoplasmic reticulum stress

Objective: This study aimed to evaluate the protective effects of curcumin (Cur) against broiler liver damage caused by exposure to polybrominated diphenyl ether (BDE-209). Methods: Four groups of 96 one-day-old broiler chicks were randomly assigned to the control group, the BDE-209 (0.4 g/kg) group, the BDE-209 (0.4 g/kg) + Cur (0.3 g/kg) group, and the Cur (0.3 g/kg) group. Following a 42-day treatment period, intestinal microbiota, hepatic inflammation response, and endoplasmic reticulum stress were assessed. Results: In the gut, BDE-209 caused severe intestinal damage, including shortened villi, increased crypt depth, disrupted tight junction structures, and ultrastructural abnormalities. Curcumin treatment alleviated these pathological changes, restored tight junction protein expression, and improved intestinal barrier function. Curcumin also reversed BDE-209‑induced gut microbiota dysbiosis by increasing beneficial bacteria such as Lactobacillus and reducing harmful bacteria including Proteobacteria. Moreover, curcumin lowered intestinal levels of key pro‑inflammatory cytokines. In the liver, BDE‑209 induced marked histopathological lesions, hepatocyte ultrastructural damage, elevated serum liver enzymes, and increased oxidative stress. Curcumin ameliorated these hepatic alterations, suppressed the activation of NF‑κB and MAPK signaling pathways, and reduced the expression of endoplasmic reticulum stress‑related proteins and genes. Conclusion: Curcumin alleviated BDE-209-induced liver damage in broilers in association with restoration of gut microbiota and reduction of inflammation and ER stress.