Mechanism of action of theophylline in bronchial asthma is :
Theophylline is used in bronchial asthma. Its mechanism of action is:

Inhibition of phosphodiesterases particularly PDE-4.
Antagonism of adenosine receptors.
Enhancement of histone deacetylation. Acetylation of histone is required for activation of inflammatory gene tran­scription. By inhibiting this process, low-dose theophylline may restore responsiveness to corticosteroids.
Phosphodiesterase 4 inhibition
Beta2 agonism
Anticholinergic action
Inhibition of mucociliary clearance