Bilirubin stabilizes the mitochondrial membranes during NLRP3 inflammasome activation

Yufei Li1, Hongda Sheng1, Ziwei Yan1

  • 1Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.

Insights

Bilirubin stabilizes mitochondrial membranes, reducing inflammation by inhibiting NLRP3 inflammasome activation. This suggests bilirubin as a potential therapeutic for inflammasome-related diseases.

Area of Science:

  • Mitochondrial biology
  • Immunology
  • Pharmacology

Background:

  • Mitochondria are key sensors of cellular stress, releasing mitochondrial reactive oxygen species (mt-ROS) that activate the NLRP3 inflammasome.
  • Regulating mitochondrial morphology and function offers a strategy against inflammation.
  • Bilirubin, at physiological concentrations, has shown anti-inflammatory effects by inhibiting NF-κB and inflammasome pathways.

Purpose of the Study:

  • To investigate the specific anti-NLRP3 inflammasome effects of bilirubin.
  • To elucidate the mechanism by which bilirubin modulates NLRP3 inflammasome activation, focusing on mitochondrial function and mt-ROS release.

Main Methods:

  • Assessed IL-1β and TNF-α release, ASC oligomer/speck formation, and pro-caspase-1 recruitment.
  • Evaluated bilirubin's effect on mt-ROS release due to its antioxidant properties.
  • Analyzed mitochondrial morphology and membrane potential in live macrophages using high-content imaging.

Main Results:

  • Bilirubin was found to target and stabilize mitochondrial membranes during NLRP3 inflammasome activation.
  • Bilirubin effectively inhibited key markers of NLRP3 inflammasome activation, including cytokine release and inflammasome complex assembly.
  • Bilirubin mitigated the release of mt-ROS and preserved mitochondrial membrane potential.

Conclusions:

  • Bilirubin demonstrates a direct inhibitory effect on NLRP3 inflammasome activation.
  • Bilirubin acts by stabilizing mitochondrial membranes and reducing mt-ROS production.
  • Defined doses of bilirubin show potential as a mitochondria-targeted therapeutic for inflammasome-related diseases.

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