Expression and significance of inositol requiting enzyme1α and tumor necrosis factor receptor-associated factor 2 in rats’ intestinal mucosa with intestinal ischemia-reperfusion injury

Abstract

Objective To investigate the expression of inositol requiting enzyme1α (IRE1α) and tumor necrosis factor receptor-associated factor 2(TRAF2) and its significance through establishing models of intestinal ischemia reperfusion injury (IIRI) in rats. Methods According to the random number table, 50 male SD rats were randomly divided into 2 groups: sham operation group (n=10) and ischemia reperfusion (I/R) group (n=40). Sham group animals underwent laparotomy.I/R group rats were subjected to occlusion of the superior mesenteric artery for 30 min; then the blood flow was restored.I/R group animals were divided into 4 subgroups: 2 h, 6 h, 12 h, 24 h according to the time of reperfusion.Eight rats were examined based on the number of live rats in each subgroup.The HE staining pathological changes in intestinal samples were observed by the light microscope.The small intestinal epithelial cell apoptosis index (AI) was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). The expression levels of intestinal tissues tumor necrosis factor α (TNF-α) and plasma intestinal fatty acid-binding protein (I-FABP) were detected by ELISA tests.Situ end labeling method was used to detect intestinal cell AI.Western blot was applied to investigate the expression of endoplasmic reticulum stress(ERS) proteins IRE1α, phosphorylation IRE1α(p-IRE1α) and TRAF2 in all group rats intestinal tissues. Results (1)The pathological changes showed that the intestinal injury of I/R groups was more severe than that of sham group, especially at 6 h. (2)Compared with sham group, the expression levels of TNF-α[sham group(16.41±4.44) ng/L, 2 h group: (79.71±8.20) ng/L, 6 h group: (131.70±11.59) ng/L, 12 h group: (94.23±7.66) ng/L, 24 h group: (69.78±9.58) ng/L], AI[sham group: (3.93±0.77)%, 2 h group: (16.24±1.97)%, 6 h group: (42.19±2.40)%, 12 h group: (37.79±2.34)%, 24 h goup: (10.38±1.46)%] and plasma I-FABP [sham group: (0.65±0.10)×103 ng/L, 2 h group: (1.47±0.10)×103 ng/L, 6 h group: (2.36±0.17) ×103 ng/L, 12 h group: (37.79±2.34) ×103 ng/L, 24 group: (1.41±0.09) ×103 ng/L] were higher (F=231.462, 149.032, 162.491, all P<0.01). (3)The expression of TRAF-2 protein and p-IRE1α/IRE1α could be up-regulated after IIRI (F=40.473, 59.59, P<0.01). The expression of these proteins was up-regulated 2 h after reperfusion, peaking at 6-12 h reperfusion, and then decreased at 24 h, and the variation tendencies of all groups were the same. Conclusions IIRI could induce ERS, activate IRE1α and up-regulate TRAF2. IRE1α/TRAF2 mediating ERS might be involved in regulating the cell inflammation, apoptosis and increasing intestinal permeability after IIRI. Key words: Intestinal ischemia reperfusion injury; Inositol requiting enzyme1α; Inflammatory; Apoptosis