Dimethyl fumarate reduces inflammatory responses in experimental colitis

Background and Aims: Fumaric acid esters have been proven to be effective for the systemic treatment of psoriasis and multiple sclerosis. We aimed to develop a new treatment for colitis. Methods: We investigated the effect of dimethylfumarate [DMF, 10-30-100 mg/kg] on an experimental model of colitis induced by dinitrobenzene sulphuric acid [DNBS]. We also evaluated the therapeutic activity of 7 weeks' treatment with DMF [30 mg/kg] on 9-week-old IL-10KO mice that spontaneously develop a T helper-1 [Th1]-dependent chronic enterocolitis after birth, that is fully established at 8-10 weeks of age. The mechanism of this pharmacological potential of DMF [10 μM] was investigated in colonic epithelial cell monolayers [Caco-2] exposed to H2O2. The barrier function was evaluated by the tight junction proteins. Results: The treatment with DMF significantly reduced the degree of haemorrhagic diarrhoea and weight loss caused by administration of DNBS. DMF [30 and 100 mg/kg] also caused a substantial reduction in the degree of colon injury, in the rise in myeloperoxidase [MPO] activity, and in the increase in tumour necrosis factor [TNF]-α expression, as well as in the up-regulation of ICAM-1 caused by DNBS in the colon. Molecular studies demonstrated that DMF impaired NF-κB signalling via reduced p65 nuclear translocalisation. DMF induced a stronger antioxidant response as evidenced by a higher expression of Mn-superoxide dismutase. Moreover, DMF protected human intestinal epithelial cells against H2O2-induced barrier dysfunction, restoring ZO-1 occludin expression, via the HO-1 pathway. Conclusions: DMF treatment reduces the degree of colitis caused by DNBS. We propose that DMF treatment may be useful in the treatment of inflammatory bowel disease.