Xuedi Zhai1, Jianshu Wang2, Jiaojiao Sun1, Lili Xin1. 1. School of Public Health, Medical College of Soochow University, 199 Renai Road, Suzhou 215123, Jiangsu, China. 2. Department of Environment Health, Suzhou Center for Disease Prevention and Control, 72 Sanxiang Road, Suzhou 215004, Jiangsu, China.
Abstract
BACKGROUND: Fine particulate matter (PM2.5) is a ubiquitous air pollutant, and it has been reported to be closely associated with lung inflammatory injury. In this study, the potential molecular mechanisms underlying PM2.5-induced cellular inflammation in human bronchial epithelial (BEAS-2B) cells were investigated. MATERIALS AND METHODS: Ambient PM2.5 particulates from Suzhou, China, were collected and re-suspended in ultrapure water. Cellular damages, characterized by oxidative stress, mitochondrial injury, and inflammatory cytokine production, were determined in 24 h PM2.5-treated BEAS-2B cells with or without 3-methyladenine (3-MA; autophagy inhibitor) pretreatment. Biomarkers related to oxidative damage, inflammatory injury and autophagy signaling pathways were also measured. RESULTS: Uptake of PM2.5 in BEAS-2B cells induced cellular oxidative damage, mitochondrial injury, and inflammatory responses as indicated by a significant decrease in GSH/GSSG ratio, increased MDA content, dilated mitochondria with loss and rupture of crista, and production of inflammatory cytokines. Activation of Nrf-2/TXNIP-mediated NF-κB and Bnip3L/NIX-dependent mitophagy signaling pathways, as well as accumulation of autophagosomes and autolysosomes, were also observed. A 6 h pretreatment of 3-MA increased PM2.5-induced oxidative damage and cellular inflammation as indicated by increasing protein levels of HO-1, TXNIP, Bnip3L/NIX and IL-8 gene expression. CONCLUSIONS: PM2.5 induced cellular inflammatory injury by oxidative stress, mitochondrial dysfunction, and mitophagy initiation. Although induction of Bnip3L/NIX-mediated mitophagy in BEAS-2B cells appeared to confer protection in response to PM2.5, dysfunction of autophagic flux may be a critical contributor to defective mitophagy and cellular inflammatory response.
BACKGROUND: Fine particulate matter (PM2.5) is a ubiquitous air pollutant, and it has been reported to be closely associated with lung inflammatory injury. In this study, the potential molecular mechanisms underlying PM2.5-induced cellular inflammation in human bronchial epithelial (BEAS-2B) cells were investigated. MATERIALS AND METHODS: Ambient PM2.5 particulates from Suzhou, China, were collected and re-suspended in ultrapure water. Cellular damages, characterized by oxidative stress, mitochondrial injury, and inflammatory cytokine production, were determined in 24 h PM2.5-treated BEAS-2B cells with or without 3-methyladenine (3-MA; autophagy inhibitor) pretreatment. Biomarkers related to oxidative damage, inflammatory injury and autophagy signaling pathways were also measured. RESULTS: Uptake of PM2.5 in BEAS-2B cells induced cellular oxidative damage, mitochondrial injury, and inflammatory responses as indicated by a significant decrease in GSH/GSSG ratio, increased MDA content, dilated mitochondria with loss and rupture of crista, and production of inflammatory cytokines. Activation of Nrf-2/TXNIP-mediated NF-κB and Bnip3L/NIX-dependent mitophagy signaling pathways, as well as accumulation of autophagosomes and autolysosomes, were also observed. A 6 h pretreatment of 3-MA increased PM2.5-induced oxidative damage and cellular inflammation as indicated by increasing protein levels of HO-1, TXNIP, Bnip3L/NIX and IL-8 gene expression. CONCLUSIONS: PM2.5 induced cellular inflammatory injury by oxidative stress, mitochondrial dysfunction, and mitophagy initiation. Although induction of Bnip3L/NIX-mediated mitophagy in BEAS-2B cells appeared to confer protection in response to PM2.5, dysfunction of autophagic flux may be a critical contributor to defective mitophagy and cellular inflammatory response.
Authors: Paul M Peeters; Irene M J Eurlings; Timothy N Perkins; Emiel F Wouters; Roel P F Schins; Paul J A Borm; Wolfgang Drommer; Niki L Reynaert; Catrin Albrecht Journal: Part Fibre Toxicol Date: 2014-11-19 Impact factor: 9.400