Table 1 Mechanism of actions of inhaled corticosteroids in asthma

Action mediated through

Cytoplasmic glucocorticoid receptor-α [9].

Membrane-bound or cytoplasmic glucocorticoid receptor or direct interaction with airway vasculature [11].

Onset of action

Hours to days [11].

Seconds to minutes [11].

Effects

- Selective switch off in multiple activated inflammatory genes (transrepression) by reversal of histone acetylation [9, 15, 16].

- Increasing mRNA degradation and hence blocking production of pro-inflammatory cytokines [11].

- Increasing the synthesis of anti-inflammatory proteins [9].

- Suppressing the increased microvascular permeability and plasma leakage into the airway lumen [29–32].

- Acutely suppressing airway hyperperfusion in a dose-dependent manner [27].

- Inhibiting the remodeling process (only long-term therapy in a dose-dependent manner) [33, 34].