Pyruvate dehydrogenase kinase supports macrophage NLRP3 inflammasome activation during acute inflammation

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• The NLRP3 inflammasome drives excessive inflammation, leading to severe tissue damage and organ dysfunction.
• Understanding regulators of NLRP3 inflammasome activation is crucial for developing anti-inflammatory therapies.

Purpose of the Study:

• To investigate the role of pyruvate dehydrogenase kinase (PDHK) in NLRP3 inflammasome activation.
• To explore the potential of PDHK inhibition as a therapeutic strategy for inflammatory conditions.

Main Methods:

• Utilized pharmacological and genetic inhibition of PDHK in murine and human macrophages and septic mice models.
• Assessed NLRP3 inflammasome activation by measuring caspase-1 cleavage and interleukin-1β (IL-1β) secretion.
• Analyzed metabolic reprogramming, autophagy, mitochondrial dynamics (fusion/fission), mitochondrial ultrastructure, and reactive oxygen species (ROS) production.

Main Results:

• PDHK inhibition significantly attenuated NLRP3 inflammasome activation, reducing caspase-1 cleavage and IL-1β secretion.
• Inhibition of PDHK reversed inflammasome-induced metabolic changes, enhanced autophagy, and promoted mitochondrial health.
• Mitochondrial ROS production was attenuated by PDHK inhibition.
• The anti-inflammatory effect of PDHK inhibition was independent of its canonical role in pyruvate dehydrogenase regulation.

Conclusions:

• Mitochondrial PDHK plays a non-canonical role in promoting mitochondrial stress and supporting NLRP3 inflammasome activation.
• Targeting PDHK offers a potential therapeutic approach to mitigate excessive inflammation and associated organ damage.