脾切除对重度热伤诱导的大鼠肠黏膜屏障破坏的影响

Splenectomy attenuates sever thermal trauma-induced intestinal barrier breakdown in rats

目的研究脾切除对重度热伤大鼠肠黏膜屏障的影响。方法 80只Wistar大鼠,随机分成对照组、热伤组(B组),热伤+脾切除7天组(B+SP7组)和热伤+脾切除14天组(B+SP14组)。对照组置于25℃水浴;热伤组于92℃水浴造成30%III度烫伤;热伤+脾切除组在热伤同时行脾切除,分别于伤后7天及14天抽血后处死。检测血清内毒素、核因子κB(nuclear factor-κB,NF-κB)和肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)含量;病理图像分析仪观察末端回肠的形态学变化,并采用Western blot法检测小肠黏膜上皮紧密连接蛋白-1(zonulaoccludens-1,ZO-1)和闭锁蛋白(occludin)的表达。结果 B组大鼠血清内毒素[(1.071±0.29)EU/mL]、NF-κB[(125±14.1)pg/mL]和TNF-α[(99.1±18.1)μg/mL]含量较对照组分别上升301%、247%和608%(P<0.01),B+SP7组较对照组分别增加226%、168%和370%,差异有统计学意义(P<0.01)。B+SP14组仅血清TNF-α较对照组上升445%,上升幅度高于7天组(P<0.01)。形态学上热伤组小肠黏膜明显萎缩,平均肠绒毛高度和黏膜厚度较对照组下降明显(P<0.01)。切除脾脏7天和14天后,平均肠绒毛高度和黏膜厚度的下降幅度小于热伤组(P<0.01)。用图像采集系统定量分析Western blot条带的相对光密度值,热伤后ZO-1(0.56±0.17)和闭锁蛋白(1.30±0.27)均明显下降(P<0.01);相对于对照组,B+SP7组的下降幅度小于热伤组(均P<0.01),B+SP14组仅闭锁蛋白的下降幅度小于B+SP7组。结论严重热伤损伤小肠黏膜屏障,脾切除后短期内由于其释放的细胞因子减少,无脾动物肠黏膜上皮细胞紧密连接蛋白表达恢复,肠屏障的损害减轻。

Objective To investigate the effects of splenectomy on severe thermal trauma-induced intestinal barrier hreakdown in rats. Methods Eighty Wistar rats were randomly divided into four groups equally as control, burn, burn ＋ splenectomy 7 days （B ＋ SP7） and burn ＋ splenectomy 14 days （B＋ SP14）. After operation 7 days and 14 days,the serum endotoxin levels,nuclear faetor-kB （NF-kB） and tumor necrosis faetor-a （TNF-a） were assayed. Small segments of terminal ileum mucosa were taken for tile determination of morphological analysis with image analysis system, and the expression of tight junction protein-1 （ZO-1） and occludin were analyzed by Western blot. Results Compared with control group, burn group significantly increased in serum endotoxin levels F（ 1. 117l ＋ 11. 29 ） EU/mI., NF-kB （ 125 ＋ 14.1 ） pg/mL,and TNF-a（99. 1 18.1 ） llg/mI.],which were 301 % ,247% and 6080//o higher than those in control group （all P〈0. {11 ）. While the values in B＋ SP7 group rose 226%,168 % and 37% than those in control group （all P^II. II1 ）. But in B ＋ SP14 group, only serum TNFa increased significantly （445 %,P〈 0. 111 ）, which was higher than in B ＋ SP7 group （P〈0.01 ）. Morphometricly the intestinal mucosa became obvious atrophy in burn group, the average intestinal villus height and mucosal thickness were decreased significantly （P〈0.01）. After splenectomy 7 days or 14 days, the extents of average intestinal villus height and mucosal thickness were less than those in burn group （P（0. I）1 ）. The relative optical density of Western blot images were significantly decreased on ZO-1 and occludin （0.56 ＋ 0.17 vs. 1.30 ＋ II. 27,P^0. 01 ） in burn group quantitatively. The degrees in B ＋ SP7 group were less than those in burn group （P^0. II1 ）. In B ＋ SPl4 group,only occludin decreased more. Conclusions This study suggested that severe thermal injury damaged the intestinal mucosal barrier. Splenectomy may provide a therapeutic benefit in restoring burn-induced intestinal barrier by decreasing the release of inflammatory cytokines and recovering tight junction proteins.