Metabolomic profiling reveals intestinal metabolic reprogramming in Chinese tongue sole (Cynoglossus semilaevis) against Vibrio harveyi infection

In this study, ultra-performance liquid chromatography-mass spectrometry (LC-MS)-based metabolomic was used to investigate the variations in intestinal metabolic phenotypes among control, susceptible, and resistant groups of Chinese tongue sole after 7 days V. harveyi infection. Histopathological results showed that susceptible fish exhibited severe intestinal mucosal dissociation, inflammatory infiltration, and muscle layer necrosis, whereas resistant fish displayed only mild structural changes. Principle components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) revealed distinct separation of intestinal metabolites among three groups. A total of 2,948 metabolites were identified, with 437 and 794 differential metabolites detected in the resistant and susceptible groups, respectively. KEGG enrichment analysis indicated that these differential metabolites were mainly involved in amino acid metabolism, purine metabolism, TCA cycle, and immune-related signaling pathways. Thirty-two potential metabolite biomarkers with high diagnostic accuracy (area under the curve (AUC) = 1) were screened, which could effectively distinguish susceptible and resistant individuals. Correlation analysis further demonstrated strong interactions among these metabolite markers, host immune-related differentially expressed genes (DEGs), and intestinal microbes.