Mechanisms implicated in glucocorticoid insensitivity in severe asthma

A number of factors including infection, oxidative stress (either directly or indirectly from cigarette smoking), allergen exposure (leading to Th2 cytokine expression), inflammation (eg, IL-17 production from Th17 and other cells), and a lack of vitamin D3 can modulate glucocorticoid function and have been shown to be important in patients with glucocorticoid resistant asthma. Drugs that target these abnormal processes or signalling pathways may prove of benefit in severe asthma.