Phosphodiesterase-4 inhibitors (eg, apremilast) Phosphodiesterase-4 (enhanced by adenosine receptor A2A agonists) Monocytes, macrophages, dendritic cells, T cells, fibroblasts Possibly inhibit production of CXCL10, interferon gamma, IL-23, TNF, and leucocyte infiltration; ameliorate pulmonary inflammation in experimental models Frequent diarrhoea