Ablation of NLRP3 inflammasome attenuates muscle atrophy via inhibiting pyroptosis, proteolysis and apoptosis following denervation

Rationale: The inflammasome has been widely reported to be involved in various myopathies, but little is known about its role in denervated muscle. Here, we explored the role of NLRP3 inflammasome activation in experimental models of denervation in vitro and in vivo. Methods: Employing muscular NLRP3 specific knock-out (NLRP3 cKO) mice, we evaluated the effects of the NLRP3 inflammasome on muscle atrophy in vivo in muscle-specific NLRP3 conditional knockout (cKO) mice subjected to sciatic nerve transection and in vitro in cells incubated with NLRP3 inflammasome activator (NIA). To evaluate the underlying mechanisms, samples were collected at different time points for RNA-sequencing (RNA-seq), and the interacting molecules were comprehensively analysed. Results: In the experimental model, NLRP3 inflammasome activation after denervation led to pyroptosis and upregulation of MuRF1 and Atrogin-1 expression, facilitating ubiquitin-proteasome system (UPS) activation, which was responsible for muscle proteolysis. Conversely, genetic knockout of NLRP3 in muscle inhibited pyroptosis-associated protein expression and significantly ameliorated muscle atrophy. Furthermore, cotreatment with shRNA-NLRP3 markedly attenuated NIA-induced C2C12 myotube pyroptosis and atrophy. Intriguingly, inhibition of NLRP3 inflammasome activation significantly suppressed apoptosis. Conclusions: These in vivo and in vitro findings demonstrate that during denervation, the NLRP3 inflammasome is activated and stimulates muscle atrophy via pyroptosis, proteolysis and apoptosis, suggesting that it may contribute to the pathogenesis of neuromuscular diseases.