Muscone Promotes PINK1/Parkin-Associated Mitophagy to Suppress NLRP3 Inflammasome Activation: Implications for Endotoxemia Therapy.

Background

The NLRP3 inflammasome drives pathological inflammation in various diseases. PINK1/Parkin-associated mitophagy serves as a critical negative regulator of NLRP3 activation, yet pharmacological enhancers remain scarce. Muscone, a natural macrocyclic ketone with blood-brain barrier permeability, exhibits potent anti-inflammatory properties; however, its mechanistic role within the NLRP3-mitophagy axis remains undefined.

Methods

LPS/ATP-stimulated macrophages were employed to assess stage-specific effects of muscone on NLRP3 priming (NF-κB signaling, NLRP3, and pro-IL-1β expression) and activation (ASC oligomerization, ASC-pro-caspase 1 complex formation, and IL-1β secretion). RNA sequencing and bioinformatic analysis were performed for pathway enrichment. Mitophagy was characterized by MitoSOX Red staining for mt-ROS detection, electron microscopy, Western blotting of LC3B-II in isolated mitochondria and PINK1 and Parkin in whole-cell lysates, and live-cell mitochondria-lysosome tracking. In vivo protective efficacy was assessed in an LPS-induced endotoxemia mouse model.

Results

Muscone dose-dependently suppressed both the priming and activation stages of the NLRP3 inflammasome, maximally reducing IL-1β secretion by ~60% at 50 μM. Mechanistically, muscone amplified PINK1/Parkin-associated mitophagy, scavenging excessive mt-ROS and attenuating NLRP3 activation. These effects were corroborated by RNA-seq and comprehensive functional assays. In vivo, muscone (30 mg/kg) significantly improved survival (3/8 mice alive at 98 h when all LPS controls had died; 2/8 survived to the 132-h endpoint), with concomitant enhancement of mitophagy markers in peritoneal macrophages.

Conclusions

Muscone functions as a PINK1/Parkin-associated mitophagy enhancer that maintains mitochondrial quality control during NLRP3-driven inflammatory responses. Its unique macrocyclic structure and blood-brain barrier permeability provide a promising scaffold for developing therapeutics against inflammatory disorders associated with NLRP3 inflammasome activation.