Modulatory effects of plasma and colonic milieu of patients with ulcerative colitis on neutrophil reactive oxygen species production in presence of a novel antioxidant, rebamipide.

Rebamipide protects gastrointestinal mucosal integrity against reactive oxygen species (ROS). The effect of rebamipide on the capability of PMNs to produce ROS in the presence of plasma and rectal dialysates (RD) of control and ulcerative colitis (UC) subjects was evaluated. We recruited six healthy volunteers for obtaining PMNs, control plasma, and control RD and six patients with inactive UC for obtaining plasma and RD. PMNs were activated using fMLP, and ROS was measured by fluorescent microplate assay (DCFD). Rebamipide significantly inhibited the neutrophil respiratory burst by 45%. Plasma from both control subjects and UC patients significantly blunted the fMLP-induced respiratory burst. However, the plasma of the UC patients was significantly less inhibitory than the plasma of control subjects. RD from control subjects significantly blunted the fMLP-induced respiratory burst while, RD from patients with UC did not. Rebamipide maintained its antioxidant effects in the presence of plasma or RD obtained from both controls and UC patients. In conclusion, partial loss of the inhibitory effects of plasma and RD in patients with UC may contribute to oxidative-induced tissue damage in UC and rebamipide antioxidant properties were not hampered by the biological milieu of patients with UC.