Abstract

BACKGROUND: Pyroptosis and oxidative stress play pivotal roles in cardiomyocyte loss after myocardial infarction. NF-κB is associated with oxidative stress and gasdermin D (GSDMD), the effector molecule of pyroptosis. However, the exact relationship between oxidative stress and cardiomyocyte pyroptosis remains unknown.

MATERIAL AND METHODS: We measured inflammasome-mediated cardiomyocyte pyroptosis in vivo via membrane pore formation, lactate dehydrogenase (LDH) release, and expression of caspase-1, cleaved caspase-1, NACHT, LRR and PYD domains-containing protein 3 (NLRP3), and apoptosis-associated speck-like protein containing a CARD (ASC). Furthermore, we induced pyroptosis in vitro by oxygen-glucose deprivation (OGD) in H9C2 cells. NLRP3 inflammasome-mediated pyroptosis was confirmed by LDH assay kit and Western blot. Oxidative stress was evaluated by reactive oxygen species (ROS) and superoxide dismutase (SOD) activity. We suppressed oxidative stress with N-acetyl-cysteine (NAC) and measured subsequent changes to the NF-κB-GSDMD axis and pyroptosis by LDH assay kit and Western blot. Then, we inhibited NF-κB activation with pyrrolidine dithiocarbamate (PDTC) and measured changes to GSDMD activity and pyroptosis by qRT-PCR, Western blot, and LDH assay kit.

RESULTS: Suppression of oxidative stress by NAC reduced NF-κB and GSDMD activation and increased pyroptosis, characterized by LDH release and NLRP3 inflammasome activation in H9C2 cells under OGD. Moreover, inhibition of NF-κB activation reduced GSDMD transcription and activation and NLRP3 inflammasome-mediated pyroptosis of H9C2 cells under OGD.

CONCLUSIONS: We demonstrated that the NF-κB-GSDMD axis functioned as a bridge between oxidative stress and NLRP3 inflammasome-mediated cardiomyocyte pyroptosis. Our findings provide important insight into the mechanism of myocardial infarction-related ventricular remodeling.

Keywords: Inflammasomes, NF-kappa B