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Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
Published on: March 2, 2014
Sendai virus C protein affects macrophage function, which plays a critical role in modulating disease severity during
Ryusuke Sakuma1, Naoko Morita1, Yukie Tanaka2
1Department of Microbiology and Immunology, Aichi Medical University School of Medicine, Aichi, Japan.
Abstract:
Sendai virus (SeV) accessory protein C limits the generation of double-stranded RNAs, defective interfering RNAs, or both, during viral transcription and replication, thereby limiting interferon-β production. Our recent in vitro analyses on murine macrophage cell lines demonstrated that this protein also contributes to restricting macrophage function, including the production of nitric oxide (NO) and inflammatory cytokines in addition to interferon-β, in infected macrophages. This study showed that depletion of airway macrophages by clodronate-loaded liposomes led to the development of severe viral pneumonia in recombinant C gene-knockout SeV (SeV∆C)-infected mice, but did not modulate disease severity in wild-type SeV-infected mice. Furthermore, the severe disease observed in macrophage-depleted, SeV∆C-infected mice was associated with exacerbated virus replication in the lungs, leading to severe airway inflammation and pulmonary edema, indicating lung injury. These results suggested that the antimacrophage activity of SeV C protein might play a critical role in modulating lung injury and associated diseases caused by SeV.
Insights
Sendai virus protein C restricts macrophage function, limiting lung injury. Its absence in mice infected with SeV∆C worsens pneumonia by increasing viral replication and inflammation.
Area of Science:
- Virology
- Immunology
- Pathology
Background:
- Sendai virus (SeV) accessory protein C modulates viral replication and host immune responses.
- Protein C limits double-stranded RNA generation, thereby restricting interferon-β production.
- Protein C also restricts macrophage functions, including nitric oxide and inflammatory cytokine production.
Purpose of the Study:
- To investigate the role of SeV protein C in modulating lung injury during SeV infection.
- To determine the contribution of macrophages to SeV-induced lung pathogenesis.
Main Methods:
- Utilized recombinant C gene-knockout SeV (SeV∆C) and wild-type SeV.
- Employed clodronate-loaded liposomes to deplete airway macrophages in mice.
- Assessed viral pneumonia severity, virus replication, lung inflammation, and pulmonary edema.
Main Results:
- Macrophage depletion exacerbated severe viral pneumonia in SeV∆C-infected mice.
- No significant difference in disease severity was observed in wild-type SeV-infected mice after macrophage depletion.
- Severe disease in macrophage-depleted, SeV∆C-infected mice correlated with increased lung virus replication, airway inflammation, and pulmonary edema.
Conclusions:
- SeV protein C's antimacrophage activity plays a critical role in limiting lung injury during SeV infection.
- The absence of protein C leads to exacerbated lung inflammation and injury due to impaired macrophage function.
- Targeting protein C's interaction with macrophages could be a therapeutic strategy for SeV-induced lung diseases.
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