Abstract

Glutamine (Gln) is the body's most abundant and versatile amino acid, playing a crucial role in immune responses. The liver, a highly vascularized and metabolically active organ, has a strong regenerative capacity and is vital for immune function, detoxification of xenobiotics, and maintaining metabolic balance. This study aimed to clarify the molecular mechanisms involved in Gln's regulation of liver functions. Dietary supplementation with 1% Gln for weaned Kele × Large White (Yorkshire) hybrid piglets (castrated male) was administered over a period of 28 days. Our findings indicate that Gln enhances liver development processes. Through mRNA sequencing, 444 differentially expressed genes (DEGs) were identified between the control group and the Gln group. Gene Ontology (GO) enrichment analysis of DEGs revealed that the top 2 enriched biological processes were the immune system and the immune response. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis highlighted several T cell-related immune pathways, including Th1 / Th2 cell differentiation, Th17 cell differentiation, and T cell receptor signaling pathway. Analysis of the KEGG pathway network and protein-protein interaction (PPI) network showed that DEGs encoding CD8 α-chain (CD8A), lymphocyte-specific protein tyrosine kinase (LCK), and linker for activation of T cells (LAT) occupy central hub positions, suggesting their critical role in immune regulation. Real-time quantitative PCR (RT-qPCR) results were consistent with the RNA sequencing data. Furthermore, Western blot analysis showed significantly increased protein expression of LCK and LAT in the Gln group, indicating the activation of the CD8A / LCK / LAT signaling axis. These results highlight Gln's immunomodulatory effects through hepatic T-cell signaling and establish a foundation for further investigation into Gln's impact on liver physiology.