Endocrine-Immune Interactions in Adrenal Function of Asthmatic Children on Inhaled Corticosteroids

The present review highlights adrenal function in the context of endocrine-immune interactions and hypothalamic-pituitary-adrenal (HPA) axis activity in asthmatic children on long-term treatment with inhaled corticosteroids (ICS). Activation of the HPA axis by specific cytokines increases the release of cortisol, which in turn feeds back and suppresses the immune reaction. Reduced responsiveness of the HPA axis in patients with various chronic allergic inflammatory disorders and a blunted HPA axis response of poorly controlled asthmatics before long-term treatment with ICS have been reported. It appears that pro- and anti-inflammatory cytokines may be involved in the attenuation of cortisol and ACTH responses to stress in these patients. ICS as anti-inflammatory agents may have favorable effects in asthmatics with baseline subnormal adrenal responses, thus improving adrenal function during successful long-term treatment; on the other hand, few patients on conventional doses may experience further deterioration of adrenal function, a phenomenon that most likely is genetically determined. When ICS are administered at high doses, secondary adrenal insufficiency due to the excessive exogenous corticosteroid certainly may become manifest.