Tu1892 Decreased SHIP1 Activity in Crohn's Disease

Abstract

Background: While the precise pathogenesis of ulcerative colitis (UC) remains unknown, the increased oxidative stress and the depressed antioxidant defense system have been involved in the pathogenesis of UC. In previous study, we identified the decreased expression of peroxiredoxin-6 (Prx-6) in murine colonic inflamed mucosa using differential proteomic analysis (J Gastroenterol Hepatol 2010). Although Prx-6 is involved in cell defense against oxidative stress and in redox regulation of intracellular signaling, the functional role of Prx6 in colonic mucosa remains to be determined. In this study, we investigated the role of Prx-6 in inflamed colonic mucosa, and the expression of Prx-6 before and after the treatment with granulocyte and monocyte adsorption (GMA). Materials and methods: The colonic expression and localization of Prx-6 were investigated using Realtime-PCR, western blotting and immunohistochemistry. At colonoscopy, biopsies were taken from normal colon mucosa in healthy volunteers and inflamed mucosa obtained from active UC patients. Furthermore, we investigated the impact of GMA treatment on the mucosal level of Prx-6 in active UC patients. In additional In Vitro study, the cytotoxicity by hydrogen peroxide and cell migration were determined in YAMC (Young Adult Mouse colonic epithelial cells) cells (as normal colonic epithelial cells) with down-regulation of Prx-6 expression by siRNA transfection. Results: The colonic expression of Prx-6 mRNA and protein was down-regulated in inflamed mucosa compared to normal colon mucosa. Immunohistochemical study showed that Prx6 expression was mainly localized in the epithelial cells. Therefore, we investigated the role of Prx-6 in the intestinal epithelial cells (YAMC cells), and hydrogen peroxide-induced cell injury was aggravated in Prx-6-downregulated YAMC cells. The wound assay revealed the delayed restitution of Prx-6-downregulated YAMC cells. In clinical study, 25 patients with active UC (14 male, 11female; mean age 47.7 years) were included and treated with GMA. The mean clinical activity index (CAI) was 12.6, and 11 of 25 patients were considered responders (a decrease of more than 5 points in CAI) after 10 GMA sessions. In responders, the colonic expression levels of Prx-6 after GMA treatment were significantly increased compared to those before GMA treatment. Interestingly, the colonic expression levels of Prx-6 before GMA treatment in responders were significantly higher than in non-responders. Conclusion: These findings indicate that down-regulated expression of Prx-6 plays a crucial role in the pathogenesis of the intestinal mucosal inflammation, and Prx-6 may be a therapeutic molecule and biomarker for the intestinal inflammation.