PDE4B and colitis: Recently Huang and colleagues reported multiple cellular defects in pediatric colitis and IBD, including impaired cyclic AMP-response signaling, infiltration of phosphodiesterase 4B and TNF-expressing macrophages, platelet aggregation and decrease in CD39-expressing intraepithelial T-cells (43); notably, administration of the phosphodiesterase inhibitor dipyridamole ameliorated colitis symptoms in a pilot study (43).