Combined effects of incubation temperature and lipopolysaccharide exposure on immune response modulation in the quail gut

Embryogenesis is a critical programming window in birds, during which environmental factors can reshape gene expression and influence adaptive capacity after hatching. However, little is known about how embryonic thermal manipulation modulates intestinal immune and metabolic responses to inflammatory challenge later in life. This study evaluated the effects of embryonic thermal manipulation on the intestinal transcriptomic response of Japanese quail (Coturnix coturnix japonica) challenged with lipopolysaccharide (LPS). A 2 × 2 factorial design was applied, including two incubation temperatures (control - 37.5°C; high - 39°C) and two challenge conditions (LPS and saline solution). At 25 days post-hatch, jejunum samples were collected after inoculation and subjected to RNA-seq analysis. High incubation temperature significantly reduced (p<0.05) hatchability but did not affect embryo morphology. Under control temperature, LPS induced differential expression of 41 genes (adjusted-p<0.05), including IL1R2, IL18BP, and S100A12, associated with inflammatory modulation and mucosal integrity. In contrast, high-temperature incubation triggered a broad transcriptomic reprogramming in response to LPS, with activation of inflammatory pathways, metabolic processes (glycolysis, Krebs cycle, pentose metabolism), lipid homeostasis, and vesicular trafficking, while simultaneously suppressing genes involved in adaptive immunity, angiogenesis, cell differentiation, and epigenetic regulation. A conserved set of inflammatory genes, including MMP7, PI3, and SLC6A14, was regulated under both thermal conditions, suggesting activation of central defense mechanisms. In conclusion, embryonic thermal manipulation did not change gross embryonic phenotype but markedly altered the magnitude and direction of intestinal gene expression responses to LPS, indicating a shift toward an innate inflammatory-metabolic profile at the expense of adaptive immune-related pathways.