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Severe neutrophil-mediated lung inflammation in myeloperoxidase-deficient mice exposed to zymosan
Kazuhiro Takeuchi1, Yu Umeki, Noriko Matsumoto
1Graduate School of Nanobioscience, Yokohama City University, Seto 22-2, Kanazawa, Yokohama 236-0027, Japan.
Objective And Design:
This study examines the role of myeloperoxidase (MPO), a major constituent of neutrophils that generates hypochlorous acid, in neutrophil recruitment into the zymosan-exposed lung of mice.
Methods:
Mice were inoculated intranasally with zymosan. The accumulation of neutrophils and other inflammatory cells within the lung was analyzed by flow cytometry. Macrophage inflammatory protein 2 (MIP-2) expression in the lung was quantified, and the contribution of this chemokine to neutrophil accumulation was examined by intranasal administration of MIP-2 antibody. The cellular sources of MIP-2 were identified, and the production of this chemokine from macrophages and neutrophils was quantified in vitro.
Results:
Zymosan exposure led to greater neutrophil infiltration into the lungs of MPO(-/-) mice relative to wild-type mice. This was associated with higher MIP-2 levels in the mutant mice. Neutralization of MIP-2 in vivo significantly reduced neutrophil infiltration. Neutrophils from MPO(-/-) mice produced more MIP-2, and the production was reduced when MPO was added exogenously.
Conclusions:
MPO deficiency results in severe lung inflammation in mice exposed to zymosan. Relatively high MIP-2 levels likely contribute to the strong inflammatory response in these animals.
Insights
Myeloperoxidase (MPO) deficiency causes severe lung inflammation in mice exposed to zymosan, leading to increased neutrophil recruitment. High levels of macrophage inflammatory protein 2 (MIP-2) likely drive this heightened inflammatory response.
Area of Science:
- Immunology
- Inflammation research
Background:
- Myeloperoxidase (MPO) is a neutrophil enzyme generating hypochlorous acid.
- Neutrophil recruitment is crucial in inflammatory responses.
Purpose of the Study:
- To investigate the role of MPO in neutrophil recruitment to the zymosan-induced lung inflammation model in mice.
Main Methods:
- Mice were exposed to zymosan intranasally.
- Neutrophil and inflammatory cell accumulation was assessed via flow cytometry.
- Macrophage inflammatory protein 2 (MIP-2) levels and production were quantified.
Main Results:
- MPO-deficient mice exhibited increased neutrophil infiltration and higher MIP-2 levels compared to wild-type mice.
- MIP-2 neutralization significantly reduced neutrophil infiltration.
- MPO-deficient neutrophils produced more MIP-2, which was attenuated by exogenous MPO.
Conclusions:
- MPO deficiency exacerbates zymosan-induced lung inflammation in mice.
- Elevated MIP-2 levels in MPO-deficient mice contribute to enhanced neutrophil recruitment and inflammation.
