Significance Of NADPH Oxidase Nox1 And Duox2 Expression In Mouse Colitis

Objective To investigate the expression and significance of NADPH oxidase Nox1 and Duox2 in pathogenesis of mouse colitis.Methods Six to eight-week-old C57BL/6 mice were randomly divided into control group, 1.5% Dextran sulfate sodium(DSS) group and 3%DSS group(n=10 for each group). The colitis model was established by free drinking water dissolved with 1.5% DSS or 3%DSS for 6 days, mice in control group was given with only drinking water. Disease Activity Index(DAI), colon length, bloody stool and HE staining scores of colon were observed. Oxidative stress indicators, Malondialdehyde(MDA) in serum and oxidized glutathione/glutathione(GSSG/GSH) ratio in colon tissue, were measured by biochemical methods. The protein and mRNA expressions of Nox1 and Duox2 in colon tissue of mice were evaluated by immunohistochemistry and quantitative real-time PCR respectively.Results 1. There was no colitis in control group, while mild and severe enteritis were found in mice with 1.5% DSS group and 3% DSS respectively: DAI scores in 1.5% group and 3% DSS were significantly higher than normal group(all P <0.05); colon length in 1.5% DSS group and 3% DSS all have different degrees of shortening, and 3% DSS group shortens seriously(all P < 0.05); There was no blood in the colon in normal mice, 1.5% DSS group and 3% DSS all have different degrees of blood compared to the control group(all P < 0.05); HE staining resulted that degree of inflammation in each group had significant differences(P < 0.05).2. Oxidative stress(MDA, GSSG/GSH) was enhanced along with the increased concentration of DSS treated mice(all P <0.05).3. The expression of NADPH oxidase, Nox1, Duox2, protein and mRNA exhibited differently with the severity of inflammation: Nox1 protein and mRNA was highly expressed in normal colon epithelial cells, while in 1.5% DSS group down regulated(P <0.05), and a further reduced in 3% DSS group(P <0.05); Duox2 protein and mRNA expression increased(P <0.05) in mice in 1.5% DSS group compared to the control group, while 3% DSS group was down to the control level.Conclusion Nox1 is mainly involved in the defense functional maintenance of normal colonic epithelium, while Duox2 may actively participate in the inflammatory pathogenesis beside defense process of colon.