Expression Of IL-21in Ischemia And Reperfusion Injury Of Mouse Intestine And DSS-induced Colitis

Objective:This study was to investigate the expression of IL-21in two models which areischemia and reperfusion injury of mouse intestine and DSS-induced colitis, and in orderto find new potential therapeutic schedule.Methods:30inbred male C57BL6wild-type mice aged12weeks were divided into three groupsequally at random：sham-operated group(I), I/RI1h group(J), and I/RI1h group(K). Briefly,under anesthesia by peritoneal injection with chloral hydrate,400mg/Kg, all animalsunderwent a midline laparotomy with evisceration of the intestine and isolation of thesuperior mesenteric artery. Thirty minutes of ischemia was induced using silk sutureapplied to the isolated artery but not in group I. The eviscerated bowel was kept moist andthe temperature of the animal controlled during ischemia. After the conclusion of ischemia,the sutures were removed and the bowel was returned to its natural intra-abdominalposition. In group J and K, animals were sacrificed after1and5hour of reperfusion. Smallbowel tissue and blood samples were collected at sacrifice.16wild-type male ICR mice, aged10–12wk, with a weight of21.53–29.35g, werehoused at room temperature on a12/12-h light-dark cycle under specific pathogen freeconditions. They were fed a standard diet, and acute colitis (group B, n=8) was induced byadministering7%(w/v) DSS (mol.wt.5000) in drinking water for7days. Healthy controlanimals (group A, n=8) received tap water only. The colon and blood samples werecollected at sacrifice.After centrifugation, the concentration of IL-21in the serum was evaluated usingmouse IL-21ELISA kits (eBioscience, USA). The specimens were fixed in4%formaldehyde, embedded in paraffin and sliced into sections of3μm thickness. After H&E staining, histological analysis was performed in a blind fashion. Thenimmunohistochemical staining with IL-21protein were performed to evaluate the contentsin the tissue.Software SPSS20.0was used in all statistical tests and the measurement data werepresented as mean(ˉX)±standard deviation (SD). Comparisons between groups werecalculated using Wilcoxon Test, and the difference was considered to be significant if the Pvalue was less than0.05.Results:1. The pathomorphological change of the tissue of each group: Group I: the intestine waspink and shiny. The intestine seems to be pale when ischemia was induced, and30minutes later, it turned to be red and lusterless. Group J: the intestine seems to be red,the wall of the intestine and mesentery congested, intestinal canal dilated and edema,exudation increased. Group K: the intestine seems to be dull with hemorrhage andnecrosis of the intestine could be found. When the mice in Group B were administeredwith DSS for7days, they drastically lost weight from the third day after initiation ofthe medication, and on day3, their stool turned to be loose. The rectal bleedingappeared at the seventh day. The mice appeared as tachypnea, cyanosis in lip, lessactivity, mess body hairs without gloss. But in Group A, the weight gained day by day,they seems to be viable and the stool was dry.2. On day1, there is no difference of the weight between Group B(26.1±2.5g) and GroupA(25.1±2.5g), P>0.05. The weight of the mice in Group B(24.2±2.2g) was less than themice in Group A(30.9±2.5g), P<0.05.3. ELISA analysis revealed that IL-21was significantly increased in Group J and B,compared with Group I and A, respectively. But there are no difference between GroupI and K and A.4. Some positive cells could be found in the epithelia of intestinal mucosa in Group I andA, but more positive cells could be found in the epithelia and propria lamina ofintestinal mucosa in Group J and K and B. Conclusions:1. IL-21maybe participate the pathogenesis of the primary I/RI in the intestine andDSS induced colitis.2. There is no difference of IL-21in serum between wild C57BL/6mouse and wildICR mouse.3. Anti-IL-21therapy may provide a potential strategy for I/RI and ulcerative colitis.