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Cystatins up-regulate nitric oxide release from interferon-gamma-activated mouse peritoneal macrophages
L Verdot1, G Lalmanach, V Vercruysse
1Laboratoire d'Enzymologie et de Chimie des Protéines, Université François Rabelais, F37032 Tours, France. bvray@med.ulb.ac.be
The Journal of Biological Chemistry
|November 8, 1996
Summary
Chicken cystatin and other cystatins up-regulate nitric oxide (NO) production in activated macrophages, independent of their cysteine proteinase inhibitory activity. This finding reveals a novel function for cystatins in modulating immune responses during Chagas
Area of Science:
- Immunology
- Parasitology
- Biochemistry
Background:
- Trypanosoma cruzi infection, the cause of Chagas' disease, leads to increased nitric oxide (NO) production by activated macrophages.
- Cruzipain, a proteinase essential for T. cruzi infection, is inhibited by cysteine proteinase inhibitors.
- Chicken cystatin, a cysteine proteinase inhibitor, was used to investigate its effect on macrophage NO release.
Purpose of the Study:
- To investigate the effect of chicken cystatin on nitric oxide (NO) production by interferon-gamma-activated macrophages.
- To determine if other cystatin families share this NO-modulating property.
- To explore the mechanism by which cystatins influence NO production.
Main Methods:
- Measurement of NO production in interferon-gamma-activated murine macrophages treated with chicken cystatin.
- Dose-response studies with chicken cystatin and other cystatin family members (stefin B, T-kininogen).
- Testing the effect of E64, aprotinin, pepstatin, and soybean trypsin inhibitor on NO production.
- Assessing cystatin activity after complexation with papain.
Main Results:
- Chicken cystatin alone significantly up-regulated NO production in a concentration-dependent manner.
- A 12-fold increase in NO was observed with 1 microM chicken cystatin, detectable at 10 nM.
- Members of all three cystatin families (stefin B, chicken cystatin, T-kininogen) enhanced NO production.
- Inhibitors of other proteases and E64 did not enhance NO production.
- Cystatins retained NO-upregulating activity even after complexation with papain, suggesting the inhibitory site is not involved.
Conclusions:
- Members of all three cystatin families possess a novel property of up-regulating NO production.
- This NO-modulating function is independent of their cysteine proteinase inhibitory activity.
- The biological significance of this cystatin-mediated NO up-regulation requires further investigation.