The Role of Skeletal Muscle Mitochondria in NLRP3 Inflammasome Signaling

Abstract

Skeletal muscle mitochondria possess the ability to autoregulate their health and functioning by the orchestration of mitochondrial quality control (MQC) pathways. This plasticity allows them to adapt to various stimuli, such as exercise. However, under pathological conditions, mitochondria can become dysfunctional, generating damage-associated molecular patterns (DAMPs), such as reactive oxygen species (ROS) and oxidized mitochondrial DNA (mtDNA). These DAMPs can launch an innate immune response, with consequences of widespread inflammation and atrophy. Integral to this is the NLRP3 inflammasome complex. Activation of the NLRP3 inflammasome results in maturation of caspase-1, which processes pro-inflammatory cytokines IL-1β and IL-18, as well as GSDMD. Consequently, the pore-forming GSDMD-N fragment induces pyroptosis, releasing mature IL-1β and IL-18. Exercise training is widely accepted as a potent mechanism to promote skeletal muscle health, particularly by remodeling the mitochondrial network and reducing the production of DAMPs. It has also been shown promote an anti-inflammatory milieu with the release of various myokines. Indeed, the potential of exercise to mitigate NLRP3 inflammasome-mediated inflammation and atrophy is promising. This review will examine the mechanisms underpinning inflammasome priming and activation, as well the effects of exercise, with an emphasis on the skeletal muscle.