The present study revealed the role of immune-metabolic crosstalk in antibody formation in hybrid groupers fed a diet containing 0.25 g/kg ethyl caffeate (EC). The experiment were divided into three groups: a negative control (NC) group, a positive control (PC) group, and an EC group. Fish were fed 0.25 g/kg of EC or control diets for 7 days and then challenged with Vibrio alginolyticus . The immune responses was analyzed over 28 days. Metabolomic and histological analyses were performed on post-challenge day 7. The growth performance was evaluated during 84 days. The results demonstrated that EC enhanced total head kidney leukocyte counts, phagocytic activity, and respiratory burst. Gene expression analysis revealed upregulation of both innate ( tlr4 , il1β , mhc2 and hsp70 ) and adaptive ( igm and igt ) immune genes, indicating humoral immunity activation. The NC, PC, and EC groups were clearly distinguished from one another using partial least squares discriminant analysis of the metabolomic data. Muscle metabolomic profiling revealed enrichment in glycolysis and tricarboxylic acid cycle metabolites, such as glucose, pyruvic acid, citric acid, and succinate. Levels of amino acid metabolites, including glutamine, arginine, L-methionine, and L-leucine, were also elevated. These metabolic alterations suggested a coordinated immune–metabolic response, whereby enhanced amino acid availability supported B-cell activation and antibody synthesis, tricarboxylic acid cycle upregulation fulfilled the energy demands of clonal expansion, and increased nucleotide metabolism facilitated cellular repair and proliferation. Thus, EC supplementation promoted antibody formation in hybrid grouper through metabolic pathways integrating energy production, biosynthesis, and immune activation, thereby enhancing disease resistance in aquaculture systems. • Dietary ethyl caffeate enhanced the innate and adaptive immune response of hybrid grouper post challenged with V. alginolyticus. • EC0.25 g/kg supplementation increased amino acid metabolites (glutamine, arginine, L-methionine, L-leucine), which support B cell activation and antibody synthesis. • Upregulation of adaptive immune genes igm and igt indicated activation of humoral immunity involving B cells. • EC0.25 g/kg increased the immune-metabolic crosstalk that promoted antibody formation in hybrid grouper post challenged with V. alginolyticus.
Widodo et al. (Sun,) studied this question.