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Pseudomonas aeruginosa promotes autophagy to suppress macrophage-mediated bacterial eradication

Yongjian Wu1, Dandan Li2, Yi Wang1

  • 1Department of Immunology, Institute of Tuberculosis Control, Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou 510080, China.

International Immunopharmacology
|June 14, 2016
PubMed
Abstract

Insights

Pseudomonas aeruginosa (PA) infection activates autophagy in macrophages, which suppresses their ability to engulf and kill the bacteria. This highlights a novel immune evasion strategy by PA.

Area of Science:

  • Immunology
  • Microbiology
  • Cell Biology

Background:

  • Pseudomonas aeruginosa (PA) is an opportunistic pathogen causing significant infections.
  • Macrophages play a crucial role in combating bacterial infections through phagocytosis and intracellular killing.
  • Autophagy is a cellular process involved in degradation and recycling, with complex roles in immunity.

Purpose of the Study:

  • To investigate the influence of autophagy on macrophage phagocytosis and intracellular killing of Pseudomonas aeruginosa.
  • To elucidate the mechanisms by which PA interacts with macrophage autophagy.

Main Methods:

  • Macrophages were infected with PA or stimulated with zymosan bioparticles.
  • Autophagy was assessed using fluorescent microscopy and Western blot for LC3.
  • Phagocytosis and killing were quantified by plate counts, flow cytometry, and immunofluorescence.
  • Gene expression, reactive oxygen species (ROS), and nitric oxide (NO) production were analyzed.

Main Results:

  • PA infection induced autophagy in both mouse and human macrophages.
  • Autophagy induction inhibited PA internalization and intracellular killing by downregulating phagocytic receptors and reducing ROS/NO production.
  • Knockdown of ATG7 or Beclin1 enhanced macrophage anti-PA activity.
  • Autophagy activation decreased phagosome and phagolysosome formation.

Conclusions:

  • Pseudomonas aeruginosa manipulates host autophagy to evade macrophage-mediated clearance.
  • This represents a novel immune evasion mechanism by PA.
  • Targeting this interaction could offer new therapeutic strategies for PA infections.
Keywords:
AutophagyBacterial killingMacrophagesPhagocytosisPseudomonas aeruginosa

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