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The phosphodiesterase ��PDE�� 4 is a predominant cyclic adenosine monophosphate ��cAMP��-degrading enzyme which can mediate inflammatory reactions via several routes. With broad anti-inflammatory activities, PDE4 inhibitors perform an antipsoriatic effect via a multifaceted and multitarget mechanism. Concretely, they can downregulate the production of pre-inflammatory cytokines including tumor necrosis factor ��TNF)-α, interferon ��IFN)-γ, interleukin��IL)-12 and IL-23 by modulating gene expression, inhibit the activation of dendrite cells and T cells and reduce the synthesis of inflammatory mediators. In addition, they have an anti-angiogenic potential. The efficacy and safety of PDE4 inhibitors have been confirmed in clinical trails. Thus, selective PDE4 inhibitors have excellent potential as new options for the treatment of psoriasis.