Fructose Promotes Crucian Carp Survival Against Aeromonas hydrophila Infection

Abstract

Aquatic food is becoming an important food source that provides micronutrients to human beings. The decline of wild aquatic animals makes aquaculture become increasingly important to play this role. However, infectious diseases, especially bacterial infection, represent severe threat to aquaculture, which causes huge economic loss. Meanwhile, strategies in managing bacterial infection in an antibiotic-independent way are still lacking. In this study, we monitor the metabolomic shift of crucian carp upon Aeromonas hydrophila infection. We find that the metabolism of the fish that died of infection is distinct from the ones that survived. By multivariate analysis, we identify fructose as a crucial biomarker whose abundance is significantly different from the dying and surviving groups where the surviving group has a higher content of fructose than the dying group. Exogenous supplementation of fructose increases fish survival rate by 27.2%. Quantitative gene expression analysis demonstrated that fructose enhances the expression of lysozyme and complement 3 expression, which is also confirmed in the serum level. Furthermore, the augmented lysozyme and C3 levels enhance serum cell lytic activity which contribute to the reduced bacterial load in vivo. Thus, our study demonstrates a metabolism-based approach to manage bacterial infection through modulating immune response to clear bacterial infection.

Succinate and inosine coordinate innate immune response to bacterial infection

“…In contrast, ATP decreases to a low concentration approximately 8 h post-treatment and then increases from 16 . This is consistent with the fact that expression of genes in the inosine salvage pathway as well as inosine respond to LPS with similar kinetics as AMP, while expression of pnp and pnp2, which converts inosine to hypoxanthine, decreased gradually in cells exposed to LPS (Figs 5E and S9).…”

“…Being treated with LPS for different time (2,4,8,12,16,24, or 36 h), cells were then coincubated with FITC-labeled Vibrio alginolyticus VS12G, Escherichia coli Y17, or Edwardsiella tarda EIB202 and phagocytosis was quantified by flow cytometry. The phagocytosis was increased along with duration of LPS treatment and peaked at and declined from 8 h posttreatment (Fig 1A).…”

“…We recently linked distinct host and bacterial phenotypes with specific metabolomes, which we refer to as “infective / anti-infective metabolomes” in host cells and “antibiotic-resistant/antibiotic-sensitive metabolomes” in bacteria. Furthermore, evidence was presented that exposure to specific exogenous metabolites can re-program “infective” to “anti-infective” or “antibiotic-resistant” to “antibiotic-sensitive” phenotypes, with corresponding metabolomic re-programming [ 16 – 19 ]…”

“…We recently linked distinct host and bacterial phenotypes with specific metabolomes, which we refer to as "infective / anti-infective metabolomes" in host cells and "antibiotic-resistant/antibiotic-sensitive metabolomes" in bacteria. Furthermore, evidence was presented that exposure to specific exogenous metabolites can re-program "infective" to "anti-infective" or "antibiotic-resistant" to "antibiotic-sensitive" phenotypes, with corresponding metabolomic re-programming [16][17][18][19] The phenotypes, functions, and activities of macrophages have been characterized extensively [4,9,20,21]. For example, in response to LPS, macrophages upregulate glycolysis and downregulate oxidative phosphorylation and tricarboxylic acid (TCA) cycle metabolism [9,22,23], which contribute to the attenuated secretion of inflammatory cytokines and reduced bacterial killing [15,24].…”

Functional proteomics identify mannitol metabolism in serum resistance and therapeutic implications in Vibrio alginolyticus

“…Overnight bacteria were diluted 1:100 in growth medium until OD600 was 1.0 at 30°C ( 69 – 71 ). Bacteria were collected for bacterial challenge.…”