Succinate and inosine coordinate innate immune response to bacterial infection

PLoS Pathog. 2022 Aug 26;18(8):e1010796. doi: 10.1371/journal.ppat.1010796. eCollection 2022 Aug.

Abstract

Macrophages restrict bacterial infection partly by stimulating phagocytosis and partly by stimulating release of cytokines and complement components. Here, we treat macrophages with LPS and a bacterial pathogen, and demonstrate that expression of cytokine IL-1β and bacterial phagocytosis increase to a transient peak 8 to 12 h post-treatment, while expression of complement component 3 (C3) continues to rise for 24 h post-treatment. Metabolomic analysis suggests a correlation between the cellular concentrations of succinate and IL-1β and of inosine and C3. This may involve a regulatory feedback mechanism, whereby succinate stimulates and inosine inhibits HIF-1α through their competitive interactions with prolyl hydroxylase. Furthermore, increased level of inosine in LPS-stimulated macrophages is linked to accumulation of adenosine monophosphate and that exogenous inosine improves the survival of bacterial pathogen-infected mice and tilapia. The implications of these data suggests potential therapeutic tools to prevent, manage or treat bacterial infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Infections*
  • Cytokines
  • Inosine / pharmacology
  • Lipopolysaccharides* / pharmacology
  • Mice
  • Phagocytosis
  • Succinic Acid

Substances

  • Cytokines
  • Lipopolysaccharides
  • Inosine
  • Succinic Acid

Grants and funding

This work was supported by the National Natural Science Foundation of China (31872602, 32061133007 and 31822058) to B. P., and (32102829) to M. J., Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) under No. 311020006 (to X.X.P), and The Youth Talent Support Program of Guangdong Province under 2017GC010617 (to B. P.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.