INTRODUCTION: Mesalazine(Pentasa) is widely used for ulcerative colitis(UC). However, the anti-inflammatory actions of Mesalazine are not fully understood. In this study, we evaluated the actions of Mesalazine in vitro on the functions of neutrophil, a major inflammatory cell. Furthermore, we evaluated the combined effects of Mesalazine and sodium ferrous citrate(SFC) on neutrophil functions, since SFC is clinically administered to UC patients together with Mesalazine for treatment of chronic anemia associated with UC.
METHODS: Superoxide production by neutrophils was measured on the basis of superoxide dismutaseinhibitable cytochrome c reduction. Preincubated neutrophils were stimulated with fMLP, PMA or complement-opsonized zymosan particles. Cytochrome c reduction was calculated by the absorbance difference at 550 nm. Neutrophil migration was measured by a Boyden chamber assay with using zymosan-activated serum (C5a) as a chemotactic factor. Neutrophils were preincubated in the presence of 0.01-0.5mM Mesalazine and then incubated with fMLP. The cells were further incubated with phycoerythrin (PE)-labeled anti-CD11b monoclonal antibody, and the expression of CD11b was analyzed by flow cytometry. Neutrophils were preincubated with 5μg/ml SFC and 0.01-0.1mM Mesalazine, and superoxide generation and migration were measured.
RESULTS: Mesalazine dose-dependently inhibited the superoxide production induced by PMA and fMLP at > 0.05 mM. Furthermore, Mesalazine inhibited chemotaxis toward zymosan-activated serum in a dosedependent fashion. Moreover, 0.5mM Mesalazine inhibited the fMLP-induced up-regulation of CD11b expression. Interestingly, Mesalazine combined with SFC inhibited the superoxide generation and migration by neutrophils, compared with Mesalazine alone. Thus, the present observations suggest that a combined administration of Mesalazine and SFC may have a potential to reduce mucosal injury by suppressing neutrophil functions (migration, ROS generation and expression of adhesion molecule) in UC.
