Identification of genes and pathways related to lipopolysaccharide signaling in duckling spleens.

Lipopolysaccharide (LPS), the major component of the outer cell wall of Gram-negative bacteria, activates the immune system and threatens the health of livestock and poultry. However, little is known about the genes and pathways involved in the immune response of ducklings to LPS. To elucidate the genes involved in the response of 7-day-old duckling spleens treated with LPS, RNA from LPS-treated and control duckling spleens was analyzed by RNA-Seq. The results showed 11,095 and 10,840 genes with >10 clean reads in the LPS-treated and control groups, respectively. Among these genes, 89 were differentially expressed (log2 ratio ≥ 1, P ≤ 0.01, false discovery rate ≤ 0.001); 67 of these were upregulated and 22 were downregulated in the LPS-treated group compared to the control. GO and GO-rich analysis showed that differentially expressed genes were enriched in 13 functional categories (P < 0.05). Pathway analysis and pathway richness analysis showed that differentially expressed genes were enriched in six pathway categories (P < 0.05). Further analysis showed that some immune system-related signaling pathways, such as the hematopoietic cell lineage, Toll-like receptor signaling pathway, T cell receptor signaling pathway, T cell receptor signaling pathway, complement and coagulation cascades, antigen processing and presentation, and chemokine signaling pathway, are active during the immune response. To confirm the RNA-Seq results, we detected CCL4, LBP, CD71, and STEAP3 expression using real-time PCR analysis, and the results were consistent with the RNA-Seq results. Our results provide new information on the genes involved in the immune response of duckling spleens to LPS.