IL6 and chronic obstructive pulmonary disease: The main objective of the present study was to investigate the effects of roflumilast and roflumilast N-oxide (particularly at the clinically relevant concentration) alone and combined with the LABA formoterol in a human bronchial explant model on the lipopolysaccharide (LPS)-induced release of tumor necrosis factor (TNF)-α, interleukin-6 (IL-6) and a panel of chemokines involved in the pathophysiology of COPD (Barnes, 2009; Barnes, 2018).