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Free iron ions decrease indoleamine 2,3-dioxygenase expression and reduce IFNgamma-induced inhibition of Chlamydia
Birgit Krausse-Opatz1, Ulrike Wittkop, Frank M Gutzki
1Department of Rheumatology, Hannover Medical School, Hannover, Germany. birgit.krausse@freenet.de
Microbial Pathogenesis
|March 25, 2009
Summary
Iron regulates indoleamine 2,3-dioxygenase (IDO) expression, crucial for immunity. This study shows iron levels impact IDO
Area of Science:
- Immunology
- Molecular Biology
- Infectious Diseases
Background:
- Interferon-gamma (IFNgamma) induces indoleamine 2,3-dioxygenase (IDO) expression, a key player in innate immunity, immune suppression, and tolerance.
- IDO facilitates tryptophan degradation, impacting cellular processes and immune responses.
- Chlamydia trachomatis (CT) infection is influenced by immune modulators like IFNgamma and IDO.
Purpose of the Study:
- To investigate the regulatory role of iron in IFNgamma-mediated IDO expression.
- To determine how iron levels affect IDO's influence on Chlamydia trachomatis infection.
- To elucidate the transcriptional control mechanisms of IDO expression involving iron.
Main Methods:
- HEp-2 cells were stimulated with IFNgamma and treated with ferrous iron (FeSO(4)) or deferoxamine (DFO) to modulate intracellular iron levels.
- IDO mRNA and protein expression were quantified.
- Tryptophan degradation levels were measured.
- The impact of iron modulation on IFNgamma-mediated suppression of Chlamydia trachomatis infection was assessed.
Main Results:
- Elevated intracellular iron (FeSO(4)) impeded IFNgamma-induced IDO expression and tryptophan degradation.
- FeSO(4) reduced or abolished the immune-suppressing effects of IFNgamma on Chlamydia trachomatis infection.
- Deferoxamine (DFO), which lowers intracellular iron, potentiated Chlamydia-suppressing effects and induced IDO expression in the absence of IFNgamma.
Conclusions:
- Iron acts as a critical regulatory element modulating IDO expression at the transcriptional level.
- Iron's dual role in regulating IDO and supporting chlamydial growth highlights its significance in host-pathogen interactions.
- This study reveals a novel control mechanism for IDO expression influenced by cellular iron availability.
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