Reactive oxygen species- (ROS-) mediated injury has been implicated in several inflammatory disorders, including
inflammatory bowel disease (IBD).
NADPH oxidases (NOXs) are the major source of endogenous ROS. Here, we investigated the role of NOXs derived-ROS in a mouse model of
colitis induced by the proinflammatory
cytokine,
tumor necrosis factor-α (TNF-α).
Intraperitoneal injection of TNFα (10 μg · kg(-1)) induced an acute
inflammation of the colon and a marked increase in expression of
NADPH oxidase 1 (NOX1), a colon specific
NADPH oxidase isoform. TNFα-induced
colitis was also characterized by high production of keratinocyte-derived
chemokine (KC) and mucosal infiltration of neutrophils, NOX2-expressing cells. Concomitantly, ROS production and lipid peroxidation were significantly enhanced while
catalase activity and
glutathione level were reduced indicating a redox imbalance in the colon. Furthermore, the redox-sensitive MAP
kinases, ERK1/2 and
p38 MAPK, were activated during TNFα-induced
colitis. Pretreatment of mice with
apocynin, an
NADPH oxidase inhibitor with
antioxidant properties, before TNFα challenge, prevented all these events. These data suggest that ROS derived from
NADPH oxidases (mainly NOX1 and NOX2) and MAP
kinase pathways could contribute to the induction and expansion of oxidative lesions characteristics of IBD and that
apocynin could potentially be beneficial in IBD treatment.