The mechanisms of prednisone inhibition of inflammation in Crohn's disease involve changes in intestinal permeability, mucosal TNFα production and nuclear factor kappa B expression

BACKGROUND: The clinical course of Crohn's disease after the induction of remission with medical therapy is characterized by unpredictable relapse. AIM: To evaluate three surrogate markers, intestinal permeability, mucosal TNFalpha and nuclear factor (NF)-kappaB/IkappaBalpha expression, in order to determine the relationship of these parameters to clinical relapse. METHODS: Thirty patients with active Crohn's disease were treated with a 10 week course of prednisone using a tapering dosing regimen. Intestinal permeability (lactulose/mannitol [L/M ratio]) was determined at baseline and at the end of prednisone tapering. TNFalpha production and the levels of expression of NF-kappaB/IkappaBalpha were measured in colonic mucosal biopsies obtained after the induction of remission. RESULTS: Twenty-two patients (73%) achieved remission and 50% of patients experienced a clinical relapse during the ensuing 12 months. Treatment with prednisone resulted in a significant decrease in the L/M ratio. Of the patients that relapsed, 75% had a raised L/M ratio at the time of remission compared with 20% of patients with a normal L/M ratio (P < 0.008; hazard ratio = 6.094; CI 1.55, 17.43). Mucosal TNFalpha production was greater in relapsers compared with those who remained in remission. The levels of NF-kappaB in relapsers were significantly greater and levels of cytosolic IkappaBalpha were significantly lower compared with those measured in patients who remained in remission. CONCLUSIONS: These findings underscore the importance of incorporating biological parameters of inflammation in determining the clinical course of Crohn's disease.