Objective To investigate the impacts of cytokines （interleukin-4，IL-4；tumor necrosis factor-α，TNF-α） and medications of bronchial asthma （dexamethasone，aminophylline，salbutamol） on the activity of histamine N-methyltransferase（HMT） in tracheal epithelial cells.Methods BEAS-2B bronchial epithelial cells were cultured and treated with different concentration of TNF-α, IL-4, dexamethasone, salbutamol and aminophylline respectively. The activity of HMT in BEAS-2B cells was determined by high performance liquid chromatography.Results The activity of HMT in tracheal epithelial cells was (50±7) pmol?min-1?mg pro-1.TNF-α and IL-4 lowered the activity of HMT significantly at the concentration equal to or higher than 1 ng/mL and 5 ng/mL respectively，and reached the maximum inhibitory effect at the level of 10 ng/mL.Dexamethasone and aminophylline could ameliorate distinctly the inhibitory effect of TNF-α on the activity of HMT, while salbutamol had no significant inhibitory effect.Conclusions TNF-α and IL-4 exert the lowering effect on the activity of HMT，which would be one important cause of airway hyperreactivity.Glucocorticoids and theophyllines are administered to treat asthma partly due to its relieving mechanism of TNF-α negative effects on HMT.
ObjectiveTo explore the effects of elafin on the regulation of mucin5AC (MUC5AC) in airway epithelial cells.MethodsAfter cultivating epithelial cells in vitro, cells were stimulated by cigarette smoke extract (CSE) and lipopolysaccharide (LPS), the intracellular MUC5AC production and extracellular secretion were assayed by immunofluorescence and ELISA, respectively.ResultsThe level of MUC5AC protein was obviously increased in the LPS stimulation group [(0.785±0.005) μg/ml vs. (0.232±0.004) μg/ml] and the CSE stimulation group [(0.803±0.005) μg/ml vs. (0.255±0.003) μg/ml] than those in the blank control groups (both P<0.01). When pretreated with elafin then stimulated by LPS and CSE, the MUC5AC productions were evidently decreased than those in the single LPS and CSE stimulation groups [(0.363±0.003) μg/ml and (0.406±0.006) μg/ml, bothP<0.01]. As compared with the blank control groups, the MUC5AC protein secretion were significantly decreased after stimulated with single elafin [(0.176±0.002) μg/ml and (0.193±0.004) μg/ml, bothP<0.05].ConclusionElafin may inhibit MUC5AC hypersecretion by blocking MUC5AC production and secretion.