In ovo carvacrol enriched inflammatory and T-cell transcriptional responses to Escherichia coli LPS in broiler chickens

The LPS challenge resulted in lower chicken weight gain and higher relative spleen weight. The <i>in ovo</i> delivery of carvacrol had no impact on these measures. The transcriptomic comparisons for the effects of LPS challenge identified 786 differentially expressed genes (DEGs) between groups 2 and 1 (without <i>in ovo</i> carvacrol) and 1,832 DEGs between groups 4 and 3 (with <i>in ovo</i> carvacrol) [false discovery rate (FDR)< 0.05, -0.5 > logFC > 0.5], primarily enriching inflammatory pathways (p< 0.01). The transcriptomic comparisons for the effects of <i>in ovo</i> carvacrol identified 89 DEGs between groups 3 and 1 and 720 DEGs between 4 and 2 (p< 0.05, -0.5 > logFC > 0.5). Functional analyses (4 vs. 2) showed that the <i>in ovo</i> delivery of carvacrol enriched pathways that can be related to T-cell activation at 6 h after LPS challenge, mainly influenced by the upregulation of DEGs encoding for cytokines and chemokines (<i>p</i>< 0.01). Overall, these findings suggest that the <i>in ovo</i> delivery of carvacrol may modulate immune responses toward an <i>E. coli</i> LPS challenge, specifically by upregulating the gene expression of cytokines, chemokines, and their receptors, persisting until at least 14 days post-hatching.