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Published on: February 23, 2014
Protease-activated receptor-1 impairs host defense in murine pneumococcal pneumonia: a controlled laboratory study
Introduction:
Streptococcus pneumoniae is the most common causative pathogen in community-acquired pneumonia. Protease-activated receptor-1 (PAR-1) is expressed by multiple cell types present in the lungs and can be activated by various proteases generated during acute inflammation. The cellular effect of PAR-1 activation partially depends on the specific protease involved. We here determined the role of PAR-1 in the host response during murine pneumococcal pneumonia.
Methods:
Wild-type (WT) and PAR-1 knockout (KO) mice were infected intranasally with viable S. pneumoniae and observed in a survival study or euthanized at 6, 24 or 48 hours of infection.
Results:
PAR-1 KO mice had a better survival early after infection compared to WT mice. Moreover, PAR-1 KO mice had lower bacterial loads in lungs and blood at 24 hours and in spleen and liver at 48 hours after infection. This favorable response was accompanied by lower lung histopathology scores and less neutrophil influx in PAR-1 KO mice.
Conclusion:
PAR-1 impairs host defense during murine pneumococcal pneumonia.
Insights
Protease-activated receptor-1 (PAR-1) impairs the immune response to Streptococcus pneumoniae pneumonia in mice. Blocking PAR-1 improved survival and reduced bacterial load, indicating its detrimental role in host defense.
Area of Science:
- Immunology
- Microbiology
- Pulmonary Medicine
Background:
- Streptococcus pneumoniae is a leading cause of community-acquired pneumonia.
- Protease-activated receptor-1 (PAR-1) is implicated in inflammatory responses.
- PAR-1 activation effects vary based on the activating protease.
Purpose of the Study:
- To investigate the role of PAR-1 in the host response to murine pneumococcal pneumonia.
Main Methods:
- Wild-type and PAR-1 knockout mice were infected with Streptococcus pneumoniae.
- Survival rates were monitored.
- Bacterial loads, lung histopathology, and neutrophil influx were assessed at various time points.
Main Results:
- PAR-1 knockout mice exhibited improved survival compared to wild-type mice.
- Lower bacterial loads were observed in PAR-1 knockout mice in lungs, blood, spleen, and liver.
- Reduced lung inflammation and neutrophil infiltration were noted in PAR-1 knockout mice.
Conclusions:
- PAR-1 plays a detrimental role in host defense against Streptococcus pneumoniae pneumonia.
- Targeting PAR-1 may represent a therapeutic strategy for pneumococcal pneumonia.
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