title: Mechanisms mediating propofol protection of pulmonary epithelial cells against lipopolysaccharide-induced cell death.
abstract: Propofol (2,6-diisopropylphenol) is an anaesthetic agent with anti-oxidant properties. The aim of the present study was to determine whether propofol can protect pulmonary epithelial (A549) cells against lipopolysaccharide (LPS)-induced cell death and, if so, the mechanisms involved. The effects of LPS alone and in combination with propofol on A549 cell death were investigated. Cell viability was determined using the colourimetric 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Apoptotic A549 cells were detected by flow cytometry, as propidium iodide-negative and annexin-V-positive cells, and terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL). Mitochondrial membrane potential (MMP), caspase 9 activity, Ca(2+)  concentrations and reactive oxygen species (ROS) were analysed by immunofluorescent methods. Aconitase 2 (ACO2), microtubule-associated light chain 3 (LC3) and beclin-1 levels were evaluated using reverse transcription-polymerase chain reaction and/or western blot analysis. Exposure of A549 cells to 1-50 μg/mL LPS for 3-24 h resulted in the concentration- and time-dependent induction of cell death. Cell apoptosis accounted for approximately 77% of cell death induced by LPS. Propofol (5-150 μmol/L) concentration-dependently inhibited LPS-induced A549 cell death. This protective effect of propofol was accompanied by prevention of LPS-induced mitochondrial dysfunction (reductions in MMP, ACO2 expression and ATP) and was associated with the inhibition of LPS-induced activation of apoptotic signals (caspase 9 activity, ROS overproduction and Ca(2+)  accumulation). In addition, propofol blocked LPS-induced overexpression of the autophagy-associated proteins LC3 and beclin-1. The data indicate that propofol protects A549 cells against LPS-induced apoptosis, and probably autophagy, by blocking LPS-induced activation of ROS/caspase 9 pathways and upregulation of LC3 and beclin-1, respectively.
authors.affiliation: Department of Anaesthesiology, Guangdong Medical College, Zhanjiang, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Gu
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Ji
authors.initials: J
authors.lastname: Chen
authors.forename: Huijuan
authors.initials: H
authors.lastname: He
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Teng
authors.initials: T
authors.lastname: Yang
authors.forename: Longxuan
authors.initials: L
authors.lastname: Li
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Chen
authors.forename: Liangqing
authors.initials: L
authors.lastname: Zhang
mesh_terms: D018686:Anesthetics, Intravenous; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D015742:Propofol / Q000494:pharmacology* / Q000627:therapeutic use; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
chemical_list: D018686:Anesthetics, Intravenous; D008070:Lipopolysaccharides; D015742:Propofol