Integrative transcriptome, proteome and microRNA analysis reveals the protective role of glutamine in β-conglycinin-induced enteritis in hybrid groupers

Feed supplementation with glutamine has been used to improve intestinal development and immunity in fish. We previously reported that dietary glutamine enhanced the growth and alleviated enteritis in juvenile hybrid groupers (female Epinephelus fuscoguttatus × male E. lanceolatus). This study further revealed the protective effect of glutamine on β-conglycinin-induced enteritis in the same species based on integrative transcriptome, proteome, and microRNA analysis. Juvenile hybrid groupers were fed 7% β-conglycinin (7S). Another group was treated with 7S supplemented with 2% alanine-glutamine (Gln), designated as Gln-vs-7S. A fishmeal (FM) group was also established. At the end of 8 weeks, based on the growth and intestinal histology, the intestines in each group were selected for multi-omics analysis to determine the protective mechanisms of Gln against foodborne enteritis. Transcriptome data based on enrichment analysis of groupers in the group treated with Gln-vs-7S revealed a discernible modulation of pathways. Specifically, a notable upregulation in immune pathways associated with peroxisome proliferator-activated receptor (PPAR) signaling pathway, tight junction, phagosome, and focal adhesion was observed (P < 0.05). Concurrently, the pathways related to the downregulation of immunoregulatory cytokine-cytokine receptor interaction, cell adhesion molecules, and NOD-like receptor signaling pathway were identified (P < 0.05). Further, integrative bioinformatics analysis of the intestinal transcriptome and proteome revealed transcription and translation of 125 differentially expressed genes (DEGs) in the Gln-vs-7S group. These DEGs showed significant enrichment in pathways associated with the intestinal epithelial barrier, such as extracellular matrix receptor interactions, focal adhesion, and tight junctions (P < 0.05). Further, the genes related to these pathways (α-actin, collagen alpha-1(I), collagen alpha-2(I), collagen alpha-1(VI), integrin-linked protein kinase, and caveolin-1) were significantly upregulated at both the transcriptional and translational levels (P < 0.05). The results of miRNA analysis indicated that the levels of both miR-192-3p_2 and miR-210-5p (their target gene cadherin-5) were significantly lower in group Gln-vs-7S (P < 0.05). In conclusion, the intestinal epithelial barrier plays a critical role in modulating the expression of miRNAs and target mRNAs/proteins in the alleviation of 7S-induced enteritis in hybrid groupers by glutamine.