Background: Although adrenomedullin (AM) is known to ameliorate inflammatory processes, few data exist regarding the effect of AM on inflammatory colitis. Therefore, we examined the effect of AM on inflammatory response in vitro and in vivo colitis model.
Methods: In mice experimental colitis induced by 3% dextran sulfate sodium (DSS) in drinking water for 7 days, AM with 225-900 μg/kg in 0.5 ml of saline or saline alone were given intraperitoneally once a day. In the in vitro experiment, we determined the cytokine response in THP-1 cell activated by lipopolysaccharide with or without AM of 10 nM. Additionally, we performed wound healing assay in Caco-2 cell interfered by DSS with or without AM of 100 nM.
Results: In the colitis model, AM significantly reduced the disease activity index, histological score, and local production of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in accordance with reduction of serum amyloid A levels. Secretion of TNF-α in lipopolysaccharide-stimulated THP-1 cells was significantly reduced in the presence of AM. The distance of wound healing interfered by 0.25% DSS was significantly improved in the presence of AM of 100 nM.
Conclusions: These results demonstrate that AM could ameliorate DSS-induced experimental colitis possibly through suppression of systemic and local production of cytokines such as TNF-α, associated with acceleration of ulcer reepithelialization and colon tissue regeneration.