Objective: To explore the role of airway smooth muscle cells (ASMC) stimulated by inflammatory factors in the development of asthma and bronchial hyperresponsiveness (BHR) and the possible mechanism of low dose theophylline in the treatment of airway inflammation, the effects of GM-CSF on endothelin-1 and endothelin converting enzyme (ECE) gene expression in human ASMC and theophylline on their expressions were investigated.
Method: The cultured human ASMCs were treated with GM-CSF (1,000 micrograms/ml), GM-CSF plus theophylline (125 ng/ml) respectively for 8 hours. Endothelin-1 and ECE gene expresion were measured by RT-PCR.
Result: There was no ET-1 gene expression in control group, but strong expression in GM-CSF treated group; theophylline entirely inhibited GM-CSF induced ET-1 gene expression in the ASMC; no significant difference of ECE gene expression was found in three groups.
Conclusion: GM-CSF causes a strong ET-1 gene expression but not ECE gene expression in cultured human airway smooth muscle cells; theophyllin inhibites this abnormal expression which may be one of the anti-inflammatory mechanisms of low dose theophylline in the management of chronic airway inflammation.