Hepatic transcriptomics and metabolomics indicated pathways associated with immune stress of broilers induced by lipopolysaccharide

Broilers with immune stress show decline of growth performance, causing severe economic losses. However, the molecular mechanisms underlying the immune stress still need to be elucidated. One hundred and twenty broiler chicks were randomly assigned to 2 groups with 6 repeats per group, 10 birds per repeat. The model broilers were intraperitoneally injection of 250 µg/kg LPS at 12, 14, 33, and 35 d of age to induce immunological stress. Control group was injected with an equivalent amount of sterile saline. Blood samples from chickens were collected using wing vein puncture at 35 d of age and the serum was obtained for detection of CORT and ACTH. At the end of the experiment, the liver tissues were excised and collected for omics analysis. The results showed that LPS challenge significantly inhibited growth performance, increased relative weight of liver, spleen and decreased relative weight of bursa, as well as enhanced the concentration of serum ACTH and CORT, when compared with the Control. A total of 129 DEGs and a total of 109 differential metabolites were identified between Model and Control group. Transcriptomics profiles revealed that immune stress enhanced the expression of genes related to defense function while declined the expression of genes related to oxidation-reduction process. Metabolomics further suggested that immune stress changed metabolites related to amino acid metabolism, glycerophospholipid metabolism. In addition, integrated analysis suggested that the imbalance of valine, leucine and isoleucine metabolism, glycerophospholipid metabolism, and mTOR signaling pathway played an important role in immune stress of broiler chicks.