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Chlamydia pneumoniae survival in macrophages is regulated by free Ca2+ dependent reactive nitrogen and oxygen species

A A Azenabor1, A U Chaudhry

  • 1Department of Health Sciences, University of Wisconsin, Milwaukee, WI 53211, USA. aazenabo@uwm.edu

The Journal of Infection
|March 14, 2003
PubMed
Abstract

Insights

Chlamydia pneumoniae survives better in macrophages lacking nitric oxide (NO), with increased reactive oxygen species (ROS). Calcium (Ca2+) and NO signaling influence bacterial growth and persistence, impacting chronic disease development.

Area of Science:

  • Immunology
  • Microbiology
  • Cell Biology

Background:

  • Chlamydia pneumoniae infections can lead to chronic diseases despite macrophage immune defenses.
  • Understanding C. pneumoniae survival mechanisms within host macrophages is crucial for disease intervention.

Purpose of the Study:

  • To investigate the growth of C. pneumoniae in macrophages with varying nitric oxide (NO) levels.
  • To determine the roles of calcium (Ca2+), NO, and reactive oxygen species (ROS) in C. pneumoniae infection.

Main Methods:

  • Culturing RAW-264.7 macrophages with sufficient (NO+) and insufficient (NO-) nitric oxide.
  • Assessing C. pneumoniae growth and inclusion formation.
  • Measuring ROS, superoxide dismutase (SOD), and catalase activities.
  • Evaluating the effects of ascorbic acid, an NO synthase inhibitor, and glutathione.

Main Results:

  • RAW-264.7 NO(-) cells showed significantly higher C. pneumoniae growth, increased ROS, SOD, and catalase activity compared to NO(+) cells.
  • Ascorbic acid, an inducible nitric oxide synthase inhibitor, and glutathione enhanced Chlamydia inclusion formation.
  • Cytosolic Ca(2+) regulated bacterial growth, NO generation, and antioxidant enzyme activities in both cell types.

Conclusions:

  • Minimal Ca(2+) signaling, alongside NO and ROS release, modulates C. pneumoniae survival, persistence, and chronicity in macrophages.
  • These factors are critical for initiating diseases where C. pneumoniae is a suspected etiological agent.

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