NF-κB Restricts Inflammasome Activation via Elimination of Damaged Mitochondria

Area of Science:

• Immunology
• Cellular Biology
• Molecular Medicine

Background:

• Nuclear factor κB (NF-κB) is crucial for inflammation, priming the NLRP3-inflammasome while also possessing poorly understood anti-inflammatory functions.
• NF-κB's dual role in inflammation necessitates understanding its regulatory mechanisms to control inflammatory responses.

Purpose of the Study:

• To elucidate the mechanism by which NF-κB restrains excessive inflammation and NLRP3-inflammasome activation.
• To investigate the role of the autophagy receptor p62/SQSTM1 in NF-κB-mediated anti-inflammatory activity.

Main Methods:

• Investigated NF-κB's anti-inflammatory effects by examining p62/SQSTM1 accumulation.
• Studied mitochondrial damage, mitophagy, and inflammasome activation in response to NLRP3 stimuli.
• Utilized macrophage-specific p62 ablation models to assess the pathway's in vivo function.

Main Results:

• NF-κB induces delayed p62 accumulation, facilitating the clearance of damaged mitochondria via mitophagy.
• NLRP3 activation triggers caspase-1/NLRP3-independent mitochondrial damage, releasing inflammasome activators like mtDNA and mtROS.
• p62 recognizes and clears Parkin-ubiquitinated damaged mitochondria, preventing excessive IL-1β-driven inflammation and macrophage death.

Conclusions:

• The NF-κB-p62-mitophagy pathway is a critical negative feedback loop controlling inflammation.
• This pathway limits NF-κB's pro-inflammatory actions, maintaining immune homeostasis and supporting tissue repair.
• Targeting this pathway could offer therapeutic strategies for inflammatory diseases.