Mitochondrial ROS and NLRP3 inflammasome in acute ozone-induced murine model of airway inflammation and bronchial hyperresponsiveness

Abstract

Oxidative stress is a key mechanism underlying ozone-induced lung injury. Mitochondria can release mitochondrial reactive oxidative species (mtROS), which may lead to the activation of NLRP3 inflammasome. The goal of this study was to examine the roles of mtROS and NLRP3 inflammasome in acute ozone-induced airway inflammation and bronchial hyperresponsiveness (BHR). C57/BL6 mice (n=8/group)were intraperitoneally treated with vehicle (phosphate buffered saline, PBS) or Mito-TEMPO (mtROS inhibitor, 20mg/Kg), or orally treated with VX-765 (caspse-1 inhibitor, 100mg/Kg) one hour before the ozone exposure (2.5ppm, 3 hour). Compared to PBS-treated ozone-exposed mice, MitoTEMPO reduced the level of total malondialdehyde in bronchoalveolar lavage (BAL) fluid and increased the expression of mitochondrial complexes II and IV in the lung 24-hour after single ozone exposure. VX-765 inhibited ozone-induced BHR, BAL total cells including neutrophils and eosinophils and BAL inflammatory cytokines including IL-1α、IL-1β、KC and IL-6. Both MitoTEMPO and VX-765 reduced ozone-induced mtROS and inhibited capase-1 activity in lung tissue whilst VX-765 further inhibited DRP1 and MFF expression, increased MFN2 expression and down-regulated caspase-1 expression in lung tissue. These results indicate that acute ozone exposure induces mitochondrial dysfunction and NLRP3 inflammasome activation, while the latter has a critical role in the pathogenesis of ozone induced airway inflammation and BHR.

Oxidative Stress in Ozone-Induced Chronic Lung Inflammation and Emphysema: A Facet of Chronic Obstructive Pulmonary Disease

“…The ozone-induced oxidative stress response might be involved in the activation of the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome complex ( 51 ). Both the acute and chronic exposure of mice to ozone induces lung inflammation through activation of ROS and of the NLRP3 inflammasome with caspase activation ( 52 , 53 ) and release of the highly inflammatory mediator IL-1β, but also IL-1α ( 54 ), which are involved in the ozone injury response ( 55 ). Uric acid crystals cause NLRP3-dependent lung inflammation upon injury ( 56 ) and therefore it is not excluded that crystals formed during injury may contribute to ozone induced inflammation ( 57 ).…”

“…In acute ozone exposed mice VX-765 is able to prevent bronchoalveolar lavage (BAL) inflammatory markers, and AHR. Mitochondrial oxidative stress was reduced and this was associated with lower expression levels of dynamin-related protein 1 (DRP1) and mitochondrial fission factor (MFF), and increased expression of Mitofusin 2 (MFN2) proteins involved in mitochondrial fission and fusion, respectively ( 53 ). Similar effects were observed in chronic ozone exposed mice were VX-765 is able to prevent inflammation, emphysema, airway remodeling, and oxidative stress while it decreased the expression of the fission protein DRP1 and MFF with affecting proteins involved in fusion dynamics.…”

“…However, airway remodeling and airflow obstruction were not ( 82 ). Similarly, in single exposure to ozone, mitoTEMPO inhibited mitochondrial ROS without affecting inflammation and bronchial hyperresponsiveness ( 53 ).…”

TRAF3 promotes ROS production and pyroptosis by targeting ULK1 ubiquitination in macrophages

“…Immunoblotting assays showed TRAF3 was abolished in PEMs and BMDMs (Figure 1A). ROS are known to promote inflammation and inflammatory cell death 22 . A main source of ROS is mitochondria, and abnormal ROS production is often associated with mitochondrial dysfunction and cell death 23 .…”

“…Mitochondrial dysfunction and amplified ROS production are key events in inflammatory diseases and are responsible for the association between chronic inflammation and increased tumor incidence 37,38 . Abnormal ROS production promotes inflammation and inflammatory programmed cell death 16,22 . TNFR‐associated factors (TRAFs) are important mediators of inflammatory reactions signaling 26,39 and ROS regulation 40 .…”