Corticosteroid effects on COPD alveolar macrophages: dependency on cell culture methodology.

It is unclear whether cell culture methodology affects the corticosteroid sensitivity of chronic obstructive pulmonary disease (COPD) alveolar macrophages. We compared the effect of a short and a long isolation procedure on corticosteroid inhibition of lipopolysaccharide (LPS) stimulated cytokine release from COPD alveolar macrophages. We also investigated signalling pathways associated with macrophage activation during cell isolation. Macrophages cultured using a short isolation protocol released higher unstimulated levels of tumour necrosis factor (TNF)-α and chemokine C-X-C motif ligand (CXCL) 8; these macrophages were less sensitive to corticosteroid inhibition of LPS stimulated TNF-α and CXCL8 release when compared to a long isolation procedure. This was associated with increased p38 mitogen activated kinase (MAPK) activation. The p38 MAPK inhibitor, BIRB-796, significantly reduced unstimulated cytokine release. A key finding of this study was that both cell culture methods showed no difference in the corticosteroid sensitivity between COPD and control macrophages. We conclude that the culture of alveolar macrophages using a short isolation procedure alters cytokine production through p38 MAPK activation; this is associated with a change in corticosteroid sensitivity.