Human Serum-derived Extracellular Vesicles Protect A549 from PM 2.5-induced Cell Apoptosis.

OBJECTIVE: Epidemiological studies reveal that exposure to fine particulate matter (aerodynamic diameter ≤ 2.5 µm, PM 2.5) increases the morbidity and mortality of respiratory diseases. Emerging evidence suggests that human circulating extracellular vesicles (EVs) may offer protective effects against injury caused by particulate matter. Currently, however, whether EVs attenuate PM 2.5-induced A549 cell apoptosis is unknown. METHODS: EVs were isolated from the serum of healthy subjects, quantified via nanoparticle tracking analysis, and qualified by the marker protein CD63. PM 2.5-exposed (50 µg/mL) A549 cells were pre-treated with 10 µg/mL EVs for 24 h. Cell viability, cell apoptosis, and AKT activation were assessed via Cell Counting Kit-8, flow cytometry, and Western blot, respectively. A rescue experiment was also performed using MK2206, an AKT inhibitor. RESULTS: PM 2.5 exposure caused a 100% increase in cell apoptosis. EVs treatment reduced cell apoptosis by 10%, promoted cell survival, and inhibited the PM 2.5-induced upregulation of Bax/Bcl2 and cleaved caspase 3/caspase 3 in PM 2.5-exposed A549 cells. Moreover, EVs treatment reversed PM 2.5-induced reductions in p-AKT Thr308 and p-AKT Ser473. AKT inhibition attenuated the anti-apoptotic effect of EVs treatment on PM 2.5-exposed A549 cells. CONCLUSIONS: EVs treatment promotes cell survival and attenuates PM 2.5-induced cell apoptosis via AKT phosphorylation. Human serum-derived EVs may be an efficacious novel therapeutic strategy in PM 2.5-induced lung injury.

Rosiglitazone inhibits PM2.5-induced cytotoxicity in human lung epithelial A549 cells.

BACKGROUND: Exposure to fine particulate matter <2.5 µm in diameter (PM2.5) leads to global adverse health effects, including increases in morbidity and mortality of respiratory diseases. PM2.5 increases production of reactive oxygen species (ROS) in the lung, which further lead to oxidative stress, cell apoptosis and cell death. According to results of previous studies, oxidative stress and subsequent cell apoptosis can be reduced by peroxisome proliferator-activated receptor gamma (PPARγ) in various cell types, however, its role in oxidative stress-related cell apoptosis caused by PM2.5 in respiratory systems is unclear. METHODS: Human lung alveolar epithelial A549 cells were exposed to PM2.5 with or without rosiglitazone (an agonist of PPARγ) treatment. Cellular apoptosis and intracellular oxidative stress were determined by flow cytometry based on FITC Annexin V and DCFH-DA fluorescence, respectively. Western blot was conducted to determine the expression of Bax, Bcl2, PPARγ, P-ERK1/2, ERK1/2, P-STAT3, and STAT3. RESULTS: PPARγ was downregulated in PM2.5-treated A549 cells, and application of rosiglitazone reduced PM2.5-mediated ROS generation and cell apoptosis. In addition, our results indicated that rosiglitazone treatment suppressed PM2.5-induced ERK1/2 and STAT3 activation. CONCLUSIONS: Collectively, these data suggested that rosiglitazone protects against PM2.5-induced ROS production and cell apoptosis and represses activation of ERK1/2 and STAT3 signaling in A549 cells. Our results indicated that rosiglitazone is a potential therapeutic agent for PM2.5-induced lung diseases.