AUTHOR=Sun Bin , Sun Boguang , Zhang Beibei , Sun Li 

TITLE=Temperature induces metabolic reprogramming in fish during bacterial infection

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.1010948

DOI=10.3389/fimmu.2022.1010948

ISSN=1664-3224

ABSTRACT=<p>Water temperature elevation as a consequence of global warming results in increased incidence of bacterial disease, such as edwardsiellosis, in fish farming. Edwardsiellosis is caused by the bacterial pathogen <italic>Edwardsiella tarda</italic> and affects many farmed fish including flounder (<italic>Paralichthys olivaceus</italic>). Currently, the effect of temperature on the metabolic response of flounder to <italic>E. tarda</italic> infection is unclear. In this study, we found that compared to low temperature (15°C), high temperature (23°C) enhanced <italic>E. tarda</italic> dissemination in flounder tissues. To examine the impact of temperature on the metabolism of flounder induced by <italic>E. tarda</italic>, comparative metabolomics were performed, which identified a large number of metabolites responsive to <italic>E. tarda</italic> invasion and temperature alteration. During <italic>E. tarda</italic> infection, the metabolic profile induced by elevated temperature was mainly featured by extensively decreased amino acids and TCA intermediates such as succinate, a proven immune regulator. Further, 38 potential metabolite markers of temperature effect (MMTE) in association with bacterial infection were identified. When used as exogenous supplements, two of the MMTE, i.e., L-methionine and UDP-glucose, effectively upregulated the expression of pro-inflammatory cytokines and suppressed <italic>E. tarda</italic> infection in flounder leukocytes. Taken together, the results of this study indicate an important influence of temperature on the metabolism of flounder during bacterial infection, which eventually affects the survivability of the fish.</p>