Effects of steroids on inflammatory cell number and function in the proximal and distal airways

Introduction: Steroids are often prescribed for patients with mild/moderate COPD but it is not clear how these community prescribed drugs affect inflammatory cell numbers/function in the proximal and distal airways. Methods: Matched proximal and distal airways tissue was obtained from 37 patients. Fourteen patients had no evidence of airways obstruction (FEV1/FVC=0.76±0.01) and 23 had evidence of mild/moderate COPD (FEV1/FVC=0.58±0.02). Eleven of these patients were prescribed steroids at the time of surgery. There were no differences in the characteristics of the patients prescribed steroids. Tissue was fixed in GMA and inflammatory cells enumerated by immunohistochemistry. Tissue explants were also stimulated with 100μg/ml anti-IgE and the release of TNFα assessed by ELISA. Results: Patients prescribed steroids had fewer mast cells in their distal airways (median=23.6 AA1+ve cells/mm 2 ) than either patients with no evidence of airways obstruction (median = 40.3 AA1+ve cells/mm 2 ) or those with COPD but not prescribed steroids (median = 59.9 AA1+ve cells/mm 2 ). There were fewer mast cells in the proximal airways of all three groups and no differences between the groups. The number of other inflammatory cells in either proximal or distal airways such as macrophages, neutrophils and CD3+ve cells were unaffected by either disease status or steroids. Anti-IgE induced TNFα release from tissue explants from proximal and distal airways was not affected by either the presence of airways obstruction or steroids. Conclusions: Mast cell numbers are reduced in the distal airways of patients with mild/moderate COPD prescribed steroids. The distribution of other inflammatory cells are not affected.