Selective inhibition of phosphodiesterase-4 ameliorates chronic colitis and prevents intestinal fibrosis.

The phosphodiesterase-4 (PDE4) inhibitors may be an important target in the treatment of several inflammatory conditions. The anti-inflammatory effect of PDE4 inhibitors bears similarities with that of steroids, without interfering with the hypophysary-adrenal-axis. We compared the effect of rolipram, a selective PDE4 inhibitor, with steroids on the clinical course of experimental colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). Three groups of rats (n = 20) received TNBS. One group received methylprednisolone from day 7, another group received rolipram from the same day, and control group received no further treatment. On days 14 and 21 after TNBS instillation, sets of 10 rats underwent colonic dialysis to measure eicosanoid release. Colonic lesions were blindly scored, and colons were homogenized for quantification of myeloperoxidase (MPO) activity and collagen content. Concentration of tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta1 (TGF-beta1) in colonic tissue was also measured. Both treatments reduced significantly the eicosanoid release and MPO activity. On day 14, both rolipram and methylprednisolone significantly reduced TNF-alpha content, but TGF-beta1 was only inhibited by rolipram. On day 21, lesion scores and collagen content were significantly reduced only in rolipram-treated group. In conclusion, PDE4 inhibition by rolipram markedly ameliorates the course of chronic colitis and it is superior to methylprednisolone in preventing late collagen deposition.