The Effect Of Myosin Light Chain Kinase On Airway Inflammation And Lung Function In Asthma Model Mice

BACKGROUNDBronchial asthma is a common chronic inflammatory disease of the respiratory tract.The main features include airway inflammation,high responsiveness of airway to multiple stimuli,wide range of reversible airflow limitation,and airway structure changing with prolonged course,that is airway remodeling.The asthma is mainly caused by the imbalance of Thl/Th2.Interleukin-2,interferon gamma(IFN-gamma)and tumor necrosis factor alpha produced by Thl cells involve in inflammation which was induced by cellular immune response.Most allergic airway inflammation is caused by the excessive increase of Th2 cells,which release cytokines,such as interleukin-4(IL-4),interleukin-5(IL-5)and so on.IL-4 and IFN-gamma are the characteristic factors in the differentiation of Thl/Th2 cells.Myosin light chain kinase(MLCK)is a kinase dependented on Ca2+-calmodulin,which plays an important role in muscle contraction.Some studies have shown that the content of myosin light chain kinase in bronchial smooth muscle cells in asthmatic patients is higher than that of normal cells.Base on the previous findings,we hypothesized the MLCK could induce the amount of inflammatory mediators and influence the lung function.The experiment was to establish a mouse model of asthma to study the effect of MLCK on airway inflammation and lung function in asthmatic mice,and to find new directions for the treatment of asthma.OBJECTIVETo study the effect of MLCK on airway inflammation and lung function in asthma.METHODSThe twenty female BALB/c mice were divided into two groups randomly:normal control group,asthma group.Established mice model of asthma by using chicken ovalbumin.On the zeroth,fourteenth day of asthma group,the OVA/aluminum hydroxide saline suspension(containing 20 gOVA and 4mg aluminum hydroxide)was sensitized by intraperitoneal injection on the first day of the asthma group.The mice of asthma group was exposed to saline or OVA administered by means of a micromist nebulizer feeding directly into the box.The control group used the same volume of physiological saline instead of sensitizer and activator.The lung function of two groups of mice was detected by pulmonary function instrument.The lungs of mice were removed and observed the pathological changes.The expression of MLCK in lung tissue was observed by immunohistochemistry.To count the number of leukocyte and eosinophil in serum under microscope.The expression of IL-4 and IFN-gamma in bronchoalveolar lavage fluid were detected by ELISA kit.The expression of MLCK in lung tissue was tested by Western blot.The expression of MLCK mRNA was detected by qPCR.RESULTS1.The tests showed that lung function in asthma group was lower than that in the control group(P<0.05);2.The count of leukocyte and eosinophil in the asthma group was higher than that of the control group(P<0.05);3.The expression of IL-4 in BALF in asthmatic mice was higher than that in the control group(P<0.05).The concentration of IFN-gamma in the asthmatic group was lower than that of the control group(P<0.05).4.The expression of MLCK protein and mRNA in asthma group were higher than that in the control group(P<0.05).CONCLUSIONMyosin light chain kinase promotes the secretion of inflammatory mediators in mice,and maybe affects airway inflammation and lung function.