Effects Of Terbutaline On The Phagocytosis Of Apoptotic Eosinophils By And The Secretions Of IL-6 And IL-8 From A549 Cells

Background:Eosinophils are the major effector cells in the pathophysilogy of bronchial asthma, which are associated with airway inflammation, airway remolding, and airway hyperresponsiveness of asthma, so eliminating eosinophils is crucial to the control of airway inflammation. Researches indicated that eosinophils could be recognized and ingested as intact cells by macrophage or airway epithelial cells after apoptosis, which play an important role in the resolution of inflammation in the asthmatic lung for preventing release of inflammatory mediators and cytotoxic substances from eosinophils.β₂-receptor agonist is one utility medicine for asthma, recent years,many experiments and researchs indicate thatβ_-receptor agonist possess not only relaxing bronchus but also anti-inflammatory. However, little is known of the pathways.Now some literatures report dexamethasone can up-regulate the capability of epithelial cell phagocytizing apoptosis eosinophils,and exist concentration rely effect. and some medicines can improve cell to phagocytize by augmenting the intra-cellular concentration of cAMP.To cure asthma the utility medicine including dexamethasone as well asβ_-receptor agonist. Canβ_-receptor agonist affect epithelial cells phagocytizing apoptosis eosinophils ?We can not know the action and mechanism about this. Now documents reportβ₂-receptor agonist can inhibit some inflammatory factors secretion,but we do not knowβ₂-receptor agonist can affect apithelial cells phagocytizing apoptosis eosinophils correlate with inhibiting the secretion of inflammatory factors. The destination of this experimentation is the mechanism of 62-receptor agonist for asthma clinical iatreusis, which this experimentation investigate the effects of terbutaline on the phagocytosis of apoptotic eosinophils by and the secretions of IL-6 and IL-8 from A549 cell.Objective:1) To investigate the effects of Terbutaline on the phagocytosis of apoptotic eosinophils by A549 cells, and the time or concentration character of Terbutaline.2) to observe the change of IL-6 and IL-8 secretions after A549 cells engulfing apoptotic eosinophils.3) to observe the change of releasing IL-6 and IL-8 from LPS-induced A549 cell by Terbutaline interfering in, and the concentration character.Methods :Eosinphils were seperated from normal human peripheral vein blood by magneticactivated separation column and micromagnetic beads coated with anti-CD 15 and anti-CD 16 . After cultured for 48 hours, eosinophils were assessed for apoptosis by morphological assessment and binding of annexin V-FITC. Apoptotic eosinophils co-culture with A549 cells which was pretreated with Terbutaline for 1 hour . Apoptotic eosinophils were stained for peroxidase with o-dianisidine and A549 cells were stained with haematoxylin after phagocytosis. Inverted microscope of Olympus and Digital Photography frame Grabber of Diagnostic Instruments-Spot insight were used to observe dynamic engulfment phenomena. Calculate the ratio of engulfment under the light microscope with the cells which were be fixed and stained. IL-6 and IL-8 in the supernatant from A549 cells were measured using radioimmunoassay kit.Results:1) The capacity of engulfment declines time by time,after A549 cells were interfered in by Terbutaline for l,2,3,hours.2) The capacity of engulfment is lowest when A549 cells were interfered in by Terbutaline with 10μmol/L.but Terbutaline with 0.1μmol/L do not inhibit significantly.3) Nothing change about the secretions of IL-6 and IL-8 from A549 cells after A549 cells engulfing apoptotic eosinophils,but lipopolysaccharide can stimulate the secretions of IL-6 and IL-8 significantly.4) Terbutaline inhibits the secretions of IL-6 and IL-8 from A549 cells ,which induced by lipopolysaccharide. And this action existe concentration relying.Conclusion:1) Terbutaline inhibits A549 cells from engulfing apoptotic eosinophils in the time and concentration manners.2 ) Terbutaline has anti-inflammatory propertie by inhibiting LPS-induced IL-6 and IL-8 secretions from A549 cells ,and this action existe concentration relying.