Article

Heterozygous SOD2 deletion deteriorated chronic intermittent hypoxia-induced lung inflammation and vascular remodeling through mtROS-NLRP3 signaling pathway

Authors: Jie-qiong Song1,2, Li-yan Jiang1, Cui-ping Fu1, Xu Wu1, Zi-long Liu1, Liang Xie1,3, Xiao-dan Wu1,3, Sheng-yu Hao1,3, Shan-qun Li1,3
1 Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China
2 Department of Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China
3 Clinical Center for Sleep Breathing Disorder and Snoring, Zhongshan Hospital, Fudan University, Shanghai 200032, China
Correspondence to: Sheng-yu Hao: janet9yu@163.com, Shan-qun Li: li.shanqun@zs-hospital.sh.cn,
DOI: 10.1038/s41401-019-0349-y
Received: 26 August 2019
Accepted: 12 December 2019
Advance online: 17 February 2020

Abstract

Oxidative stress caused by chronic intermittent hypoxia (CIH) is the hallmark of obstructive sleep apnea (OSA). Among the first line of defense against oxidative stress is the dismutation of superoxide radicals, which in the mitochondria is carried out by manganese superoxide dismutase (SOD2). In this study, wild-type (WT) and SOD2-heterozygous knockout (SOD2+/−) mice were exposed to CIH or normoxic (Nor) conditions. After 4 weeks, pulmonary artery pressure was measured, and the mice were processed to harvest either serum for cytokine assays or lungs for flow cytometry and histopathological studies. Herein, we showed that heterozygous deletion of SOD2 markedly deteriorated pulmonary remodeling and increased the oxidative stress, especially promoted the infiltration of macrophages in the lungs of CIH mouse. Moreover, in the intermittent hypoxia (IH)-treated RAW264.7 cells, SOD2 knockdown increased the nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome activation accompanied with the IL-1β elevation and caspase-1 activity. Additionally, mitochondrial ROS (mtROS) scavenger mito-TEMPO abolished NLRP3 inflammasome activation in IH-treated RAW264.7 cells. Collectively, our results supported that SOD2 contributed to the pathogenesis of CIH-induced lung remodeling. Meanwhile, SOD2 knockdown exacerbates oxidative damage through assembly and activation of NLRP3 inflammasome in macrophages. SOD2 may be a novel therapeutic target for CIH-induced pulmonary inflammation and arteriole remodeling.
Keywords: SOD2; intermittent hypoxia; inflammation; NLRP3; macrophage

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