Expression And Significance Of Endoplasmic Reticulum Stress Proteins In The Colitis Model Of Cyp4a14 Knockout Mice

Background: Inflammatory bowel disease(IBD)is characterized by chronic idiopathic relapsing and remitting inflammatory of the gastrointestinal tract.Endoplasmic reticulum(ER)stress involved in the process of a various diseases,include IBD.Cyp4a14 is an enzyme in liver which is related to lipid peroxidation and oxidative stress.However,how did Cyp4a14 gene participate in the occurrence and procession of colitis,and its relationship with ERS is still unclear.Aims: In this study we examine the expression of ER stress molecules in Cyp4a14 knockout mouse colitis induced by dextran sodium sulphate(DSS)and analyses their significance in pathogenesis of the colitis.Methods: Cyp4a14 knockout(KO)and wild-type(WT)male mice with129S1/SvJ background were randomly divided into KO control,KO DSS,WT control and WT DSS,eight in each group.Control groups treated with drinking water,and DSS groups with 3.0% DSS to induce acute colitis.At the 6th day,all the mices were scarified.Colitis score in mice was evaluated by weight loss,disease activity index(DAI),colon length and histopathology.The colonic mRNA levels of inflammatory cytokines(IL-1?,IL-6 and TNF-?)and ER stress biological molecules(GRP78,IRE1?,XBP1 u,XBP1s,IRE1?,PERK,ATF6 and CHOP)and mRNA of Cyp4a14 level were measured by quantitative real-time(RT)PCR.GRP78,ATF6 and CHOP proteins were evaluated by Western blot and immunohistochemistry and Cyp4a14 protein by Western blot.Results:1.There was no colitis in WT and KO control groups,mild colitis was found in mice of KO DSS group.However,mice in WT DSS had severe colitis.In WT DSS and KO DSS group,DAI and histopathology scores were all higher than the control group significantly(all P<0.05),and both scores of WT DSS group were higher than KO DSS group(all P<0.05).the colon length shorten seriously in WT DSS group(all P<0.05).2.The colonic mRNA levels of IL-1?,IL-6 and TNF-? were increased in WT and KO DSS groups(all P<0.05).And IL-6 and TNF-? mRNA were higher in WT DSS group than KO DSS group(all P<0.05).3.There was no significant difference in IRE1?,XBP1 u and PERK mRNAbetween the inflammatory groups and the control groups,but the expression of IRE1?mRNA in WT and KO DSS groups was significantly down-regulated(P<0.05).The expression of XBP1 s in WT DSS group was lower than that in control group(P<0.05),and the expression of ATF6 and CHOP mRNA was higher in WT DSS group than that in control group(all P<0.05),but there was no difference between KO DSS group and KO control group.4.The expression of Cyp4a14 mRNA and protein in the liver of WT DSS group was significantly down-regulated(all P<0.05).5.The levels of GRP78,ATF6,CHOP mRNA and protein in WT DSS group were significantly higher than those in control group(all P<0.05).Conclusions:1.The Cyp4a14 gene knockout mice can resist DSS-induced colitis.2.Cyp4a14 gene may play an important role in the pathological process of IBD by affecting the expression of ATF6,CHOP and XBP1 s mRNA in ERS.3.The activity of GRP78-ATF6-CHOP pathway of ER stress is involved in the pathogenesis of IBD.