AUTHOR=Gregorich Jenna L. , Lilburn Michael S. , Shanmugasundaram Revathi 

TITLE=Effects of Induced Moisture Loss in Chicken Embryos at Embryonic Day 18 and Post-hatch Immune Response During Salmonella enteritidis Lipopolysaccharide Challenge in Broilers

JOURNAL=Frontiers in Physiology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.820349

DOI=10.3389/fphys.2022.820349

ISSN=1664-042X

ABSTRACT=Two experiments were conducted to investigate the effects of induced moisture loss on embryonic development and the immune response following an inflammatory challenge. In Experiment I, fertile leghorn eggs (n=100) and commercial broiler eggs (n=300) were set at 37.5°C and moisture loss was induced in one-half of the Leghorn and broiler eggs by drilling two, 1.5 mm diameter holes. The Control eggs had 0 holes. At embryonic day (ED)18, layer and broiler eggs in the 2-hole treatment had a significant (P < 0.01) increase in moisture loss compared to the control treatment (10.1% vs. 8.2%; 9.9% vs. 8.4%). Thymocytes from leghorn (104%) and broiler (62%) embryos in the 2-holes treatment had significantly increased in vitro proliferation compared with the control embryos (P < 0.05). At ED18, layer and broiler embryos in the 2-hole treatment had an approximate 2 fold increase in the splenic CD8+/CD4+ ratio (P < 0.05) and CD4+CD25+ cells percentage in both the thymus and spleen (P < 0.05). At ED18, both layer and broiler embryos from the 2-hole treatment had a significant increase in splenic IL1-β, IL-6, IL-10, and TLR-4 mRNA transcription compared to the control group (P < 0.05). Experiment II was repeated with 300 fertile broiler eggs. Chicks were randomly distributed into one of four treatments in a 2 (0, 2 holes) X 2 (0, 500 µg LPS) factorial setup. At 24h and 48h post-hatch, chicks hatched from eggs with 2-holes and challenged with LPS had a significant increase (P < 0.05) in thymocyte proliferation at 24h and 48h when compared with chicks hatched from the control (0-hole; 0 µg LPS) treatment. Chicks hatched from the 2- hole treatment and challenged with the LPS had an approximately 2 fold higher splenic CD8+/CD4+ ratio and 1.5 fold increase in CD4+CD25+ percentage compared to control chicks (P ≤ 0.05). In chicks hatched from the 2-hole treatment, MUC2 mRNA transcription was comparable to control chicks at 24h and 48h in response to the LPS challenge. Our data suggest that the 2-hole treatment reprograms gene transcription to facilitate cell survival via proliferation and differentiation during an LPS inflammatory challenge.