ABSTRACT
Objective To investigate the protective effect and underlying mechanism of the superoxide dismutase mimic, manganese (Ⅲ) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), on paraquat (PQ) -induced lung epithelial-like cell injury. Methods Alveolar epithelial-like cells (A549) were pretreated with 10 μmol/L of MnTMPyP for 1.5 h and then cultured with or without PQ (750 μmol/L) for 24 h. Cell survival was determined using the MTT assay. Reactive oxygen species (ROS) production and Ca2+ levels were measured using flow cytometry. Glutathione reductase (GR) activity was determined using spectrophotometry. Expressions of the endoplasmic reticulum (ER) stress proteins, glucose regulatory protein 78 (Grp78) and C/EBP homologous protein (CHOP), were measured using Western blotting. Results Cell viability and GR activity were decreased, but ROS production, cytoplasmic Ca2+ levels, and expressions of Grp78 and CHOP were all increased in the PQ group compared to those in the control group. There were no statistically significant changes in the MnTMPyP group. Cell viability and GR activity were increased, while ROS production, cytoplasmic Ca2+ levels, and expressions of Grp78 and CHOP were all significantly reduced in the MnTMPyP group compared to those in the PQ group. Conclusion MnTMPyP effectively reduced PQ-induced lung epithelial-like cell injury, and the underlying mechanism is related to antagonism of PQ-induced ER stress and oxidative stress.
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Objective To investigate the apoptosis mechanism induced by paraquat (PQ) in human type Ⅱ alveolar epithelial-like A549 cells.Methods A549 cells were cultured in vitro.The cells in the experimental group were exposed to various concentrations of PQ (50,100,150,and 200 μmol/L),while those in the control group were cultured in RPMI1640 medium.After treatment for 24 and 48 h,the cell survival rate was assessed by MTT assay.Morphological changes in the nuclei were observed by Hoechst 33258 fluorescence staining.Cellular apoptosis and mitochondrial transmembrane potential were assayed by flow cytometry.The activities of caspase-3 and caspase-9 were assayed by spectrophotometry.Western blotting was used to analyze the expression of proteins in the Bcl-2 family,such as Bcl-2,Bcl-xL,Bax,and Bak.Results PQ exhibited significant anti-proliferative activity in A549 cells.PQ-treated A549 cells were subjected to Hoechst 33258 staining.The hallmarks of apoptosis were detected,and the degree of apoptosis increased.Mitochondrial membrane potential was decreased,the levels of active caspase-3 and caspase-9 increased,the expression of Bcl-2 and Bcl-xL was decreased,and the expression of Bax and Bak was increased.These effects occurred in concentration-and time-dependent manners.Conclusion PQ efficiently induced intracellular apoptosis through the mitochondrial pathway in A549 cells.
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Objective To clarify the role and significance of Toll?like receptor 4(TLR4)in myocardial damage following paraquat(PQ)poisoning in mice. Methods Male wild type C57BL/6J mice(WT)and male TLR4 deficient mice(TLR4?ko)were divided into four groups in the study:(1)control group(WT mice,n=6);(2)TLR4?ko group(TLR4?ko mice,n=6);(3)WT+PQ group(WT mice,n=30);(4)TLR4?ko+PQ group (TLR4?ko mice,n=30). The mice in group 1 and group 2 were injected intraperitoneally with saline;mice in group 3 and group 4 were injected in?traperitoneally with 75 mg/kg of PQ. At 2 h,4 h,8 h,16 h and 24 h after PQ administration,6 mice of WT+PQ group and TLR4?ko+PQ group were euthanized and the heart tissue specimens were harvested. All the specimens were analysed by histology,while the expression of TLR4 mRNA was only detected in samples of WT+PQ mice. The specimens at 2 h,8 h and 24 h after PQ administration were used for cytokines detection for WT+PQ group and TLR4?ko+PQ group;in addition,Western blot analysis was performed for WT+PQ group. At 8 h after treatment,control mice and TLR4?ko mice were euthanized by the same method. Mice were anesthetized for cardiac geometry and functional assessment using a 2?D guide M?mode echocardiography at 8 h following injection of either PQ or saline. Results During myocardial damage due to PQ exposure in WT+PQ mice,obvious histopathological changes were observed,as well as a noticeable decrease of heart function and increased expressions of TNF?αand IL?1β. Compared with the WT mice,TNF?αand IL?1βprotein levels,changes in heart function and histopathological changes were significantly attenuated following PQ exposure in myocardial damage in TLR4?ko mice. Conclusion The TLR4gene is involved with in heart functional injury and histopathological changes in myocardial damage following PQ poisoning in mice,which may through the regulation of TNF?αand IL?1βexpression. Our findings indi?cate that TLR4 plays an important role in mediating myocardial injury due to PQ.