Regulation of inflammatory cell function by corticosteroids

Different inflammatory cell profiles are observed in the lungs of patients with asthma versus those with chronic obstructive pulmonary disease (COPD). In asthma, several key mediators have been implicated, including tumor necrosis factor-alpha and interleukin (IL)-1beta, together with cytokines derived from type 2 T-helper lymphocytes, such as IL-4, IL-5, and IL-13. In fact, inhibitors of IL-4 and IL-5 show promise as therapeutic agents. In COPD, the predominant inflammatory cell types are CD8(+) T lymphocytes, macrophages, and neutrophils. Glucocorticoids inhibit eosinophils in asthma, neutrophils in COPD and severe asthma, mast cells and basophils in asthma and COPD, and macrophages in COPD. However, it is generally assumed that neutrophils are less sensitive to glucocorticoids than are eosinophils and T cells, and that macrophages from patients with COPD are less sensitive to steroid treatment under certain circumstances. These differences in the responsiveness of activated inflammatory cells may help to explain why inhaled corticosteroid treatment has been more beneficial for patients with asthma than for patients with COPD.