Roflumilast inhibits the release of chemokines and TNF-α from human lung macrophages stimulated with lipopolysaccharide

Abstract

Background and purpose: Lung macrophages are critically involved in respiratory diseases. This study assessed the effects of the PDE4 inhibitor roflumilast and its active metabolite, roflumilast N-oxide on the release of a range of chemokines (CCL2, 3, 4, CXCL1, 8, 10) and of TNF-α, from human lung macrophages, stimulated with bacterial lipopolysaccharide LPS. Experimental approach: Lung macrophages isolated from resected human lungs were incubated with roflumilast, roflumilast N-oxide, PGE 2, the COX inhibitor indomethacin, the COX-2 inhibitor NS-398 or vehicle and stimulated with LPS (24 h). Chemokines, TNF-α, PGE 2 and 6-keto PGF 1α were measured in culture supernatants by immunoassay. COX-2 mRNA expression was assessed with RT-qPCR. PDE activities were determined in macrophage homogenates. Key results: Expression of PDE4 in lung macrophages was increased after incubation with LPS. Roflumilast and roflumilast N-oxide concentration- dependently reduced the LPS-stimulated release of CCL2, CCL3, CCL4, CXCL10 and TNF-α from human lung macrophages, whereas that of CXCL1 or CXCL8 was not altered. This reduction by the PDE4 inhibitors was further accentuated by exogenous PGE 2 (10 nM) but abolished in the presence of indomethacin or NS-398. Conversely, addition of PGE 2(10 nM), in the presence of indomethacin restored inhibition by roflumilast. LPS also increased PGE 2and 6-keto PGF 1α release from lung macrophages which was associated with an up-regulation of COX-2 mRNA. Conclusions and implications: Roflumilast and roflumilast N-oxide reduced LPS-induced release of CCL2, 3, 4, CXCL10 and TNF-α in human lung macrophages. © 2011 The British Pharmacological Society.