ORIGINAL RESEARCH article
Front. Immunol.
Sec. Nutritional Immunology
In ovo carvacrol enriched inflammatory and T-cell transcriptional responses to Escherichia coli LPS in broiler chickens
Mila Meijer 1
Henry van den Brand 2
Shahram Niknafs 1
Eugeni Roura 1
1. The University of Queensland QAAFI Centre for Animal Science, Saint Lucia, Australia
2. Adaptation Physiology Group, Wageningen University & Research, Wageningen, Netherlands
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Abstract
Enhancing immune responsiveness against pathogens is crucial for maintaining health. In broiler chickens the in ovo delivery of carvacrol, a phenolic compound found in oregano and thyme, has shown promising immunomodulatory activity. This study investigated the hypothesis that in ovo delivery of carvacrol would regulate the immune response against E. coli lipopolysaccharide (LPS) in broiler chickens. In ovo carvacrol (injected at embryonic day 17.5) and/or and E. coli LPS challenge (repeated intraperitoneal injections at post-hatching d7 and 14) were tested in a 2 x 2 factorial arrangement, resulting in four groups: (1) in ovo saline without challenge (saline), (2) in ovo saline with LPS challenge, (3) in ovo carvacrol without challenge, (4) in ovo carvacrol with LPS challenge. Performance parameters were collected, and relative organ weights were measured at d14. Splenic samples were collected 6h after the second challenge (d14) and used for transcriptomic analyses. The LPS challenge resulted in lower chicken weight gain and higher relative spleen weight. The in ovo delivery of carvacrol had no impact on these measures. The transcriptomic comparisons for the effects of LPS challenge identified 786 differentially expressed genes (DEG) between groups (2) and (1) (without in ovo carvacrol), and 1832 DEG between groups (4) and (3) (with in ovo carvacrol) (FDR < 0.05, -0.5> logFC > 0.5), primarily enriching inflammatory pathways (P < 0.01). The transcriptomic comparisons for the effects of in ovo carvacrol identified 89 DEG between groups (3) and (1), and 720 DEG between (4) and (2) (P < 0.05, -0.5 > logFC > 0.5). Functional analyses (4 vs 2) showed that in ovo delivery of carvacrol enriched pathways that can be related to T-cell activation at 6h after LPS challenge, mainly influenced by upregulation of DEG encoding for cytokines and chemokines (P < 0.01). Overall, these findings suggest that in ovo delivery of carvacrol may modulate immune responses towards an E. coli LPS challenge, specifically by upregulating gene expression of cytokines, chemokines and their receptors, persisting until at least 14 d post-hatching.
Summary
Keywords
broiler chicken, Broiler embryo, carvacrol, Immunomodulation, in ovo, LPS, Transcriptomics
Received
05 December 2025
Accepted
19 January 2026
Copyright
© 2026 Meijer, van den Brand, Niknafs and Roura. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Eugeni Roura
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