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Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
08:32

Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production

Published on: March 2, 2014

Receptor interacting protein kinase 2-mediated mitophagy regulates inflammasome activation during virus infection

Christopher Lupfer1, Paul G Thomas, Paras K Anand

  • 1Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.

Nature Immunology
|March 26, 2013
PubMed

Insights

The NOD2-RIPK2 immune pathway protects against influenza by regulating mitophagy. This pathway prevents excessive inflammasome activation and IL-18 production, mitigating viral infection pathology.

Area of Science:

  • Immunology
  • Virology
  • Cell Biology

Background:

  • The NOD2 receptor and RIPK2 kinase pathway are crucial for bacterial infection response.
  • The role of this immune axis in viral infections, particularly influenza, remains unexplored.

Purpose of the Study:

  • To investigate the function of the NOD2-RIPK2 signaling axis in viral infections.
  • To elucidate the mechanisms by which this pathway influences host defense against influenza A virus.

Main Methods:

  • Utilized knockout mouse models (Nod2(-/-) and Ripk2(-/-)) to study influenza A virus infection.
  • Analyzed cellular processes including autophagy, mitophagy, mitochondrial reactive oxygen species production, and inflammasome activation (NLRP3).
  • Investigated the kinase-dependent regulation of mitophagy by RIPK2, focusing on the phosphorylation of ULK1.

Main Results:

  • Nod2(-/-) and Ripk2(-/-) mice showed increased susceptibility to influenza A virus infection.
  • Ripk2(-/-) cells displayed impaired mitophagy, leading to increased mitochondrial superoxide production and damaged mitochondria.
  • This resulted in heightened NLRP3 inflammasome activation and IL-18 production.
  • RIPK2 kinase activity was essential for mitophagy, phosphorylating ULK1.
  • Ulk1(-/-) cells exhibited increased mitochondrial superoxide and caspase-1 activation.

Conclusions:

  • The NOD2-RIPK2 pathway plays a protective role against viral infections like influenza.
  • This pathway negatively regulates NLRP3 inflammasome activation and IL-18 production through ULK1-dependent mitophagy.
  • NOD2-RIPK2 signaling is critical for preventing virally triggered immunopathology by controlling mitochondrial homeostasis and inflammation.

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