Background & aims: Increased free radicals and/or impaired antioxidant defenses have been shown to play a pathogenetic role in human and animal models of inflammatory bowel disease. Our previous studies showed that prohibitin (PHB) levels are decreased during colitis and that cultured intestinal epithelial cells overexpressing PHB are protected from oxidative stress. This study investigated the effect of intestinal epithelial cell-specific PHB overexpression on oxidative stress associated with experimental colitis and the potential mechanism by which PHB functions as an antioxidant using PHB transgenic mice.
Methods: Colitis was induced using 2 established mouse models (Salmonella typhimurium and dextran sodium sulfate) in PHB transgenic mice and wild-type littermates. Oxidative stress was determined by measuring glutathione and protein carbonyl levels in the cecum or colon. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional regulator of oxidant responses, expression, and activation, was assessed in colon mucosa and cultured intestinal epithelial cells overexpressing PHB.
Results: Cells overexpressing PHB showed sustained Nrf2 nuclear accumulation and DNA binding during oxidant stress. PHB transgenic mice exhibited decreased oxidative stress and colitis and increased Nrf2 messenger RNA expression, nuclear protein translocation, and DNA binding compared with wild-type littermates during colitis.
Conclusions: These results show that PHB is a regulator of Nrf2 expression in intestinal epithelial cells during oxidative conditions and prevents inflammation-associated oxidative stress and injury through sustained activation of Nrf2. Our data show that PHB is a novel regulator of antioxidants and suggest that restoration of PHB levels represents a potential therapeutic approach in inflammatory bowel disease.