Induction of hepatic immuno-oxidative stress in broilers by co-exposure to lipopolysaccharide and diquat: An integrated phenotypic and transcriptomic investigation

Although immunological and oxidative stresses frequently coincide in poultry production, research to develop immuno-oxidative stress models in broilers using established chemical approaches remains scarce. This study aimed to develop a model of concurrent hepatic immuno-oxidative stress in broilers by co-administrating lipopolysaccharide (LPS) and diquat (DQ), and to investigate the underlying mechanisms. A total of 120 one-day-old male Arbor Acres broiler chicks were randomly assigned to either a control group or a challenge group. On day 42, broilers in the challenge group received an intraperitoneal injection of LPS (1 mg/kg body weight) and DQ (20 mg/kg body weight), while controls received saline. The combined challenge increased both absolute and relative liver weights and impaired liver function, as indicated by decreased total protein and albumin levels and cholinesterase activity, along with elevated triglyceride concentration and alanine aminotransferase activity (P < 0.05). Histopathological examination demonstrated extensive liver damage characterized by hepatocyte vacuolation, architectural disorganization, and inflammatory infiltration, accompanied by an elevated apoptotic rate of hepatocytes (P < 0.05). The challenge triggered a pronounced inflammatory response, elevating serum interferon-γ and interleukin-6 levels and hepatic interleukin-1β and tumor necrosis factor-α levels (P < 0.05). Moreover, it induced marked systemic and hepatic oxidative stress, as evidenced by decreased activities of superoxide dismutase, glutathione peroxidase, and catalase, reduced glutathione level, and increased malondialdehyde concentration (P < 0.05). Gene Ontology enrichment analysis indicated that the differentially expressed genes were predominantly involved in metabolic processes, cellular responses to chemical stimuli, and oxidoreductase activity. Kyoto Encyclopedia of Genes and Genomes pathway analysis further highlighted significant enrichment in amino acid, lipid, and carbohydrate metabolism pathways, metabolism of xenobiotics by cytochrome P450, peroxisome proliferator-activated receptor signaling, and pathways related to cytokine-cytokine receptor interaction and tumor necrosis factor signaling. The findings demonstrate that co-exposure to LPS and DQ induces significant liver damage, triggers a marked inflammatory response, and disrupts hepatic redox balance, which is mechanistically linked to transcriptomic perturbations in metabolic and inflammatory pathways and redox homeostasis.