PDE4A and psoriasis: Elevated intracellular cAMP levels were detected in UC patients, leading to downregulation of the inflammatory response in the mucosa (NF-κB, TNF-α, IL-1β, IL-17, IL-23 etc).[17,18] Based upon this, some specialists suggest apremilast as a third-line option for psoriasis patients with comorbid UC.[19] Although a previous study demonstrated similar levels of PDE-4 in PSC patients compared to the healthy subjects, PDE-4 is considered to play a role in attenuating fibrogenic signaling in a bile-duct ligation liver fibrosis rat model.[20,21]