细胞外组蛋白对损伤小鼠肠黏膜屏障的影响及在脓毒症发生发展中的作用

Effect of extracellular histones on intestinal mucosa barrier function in mice and role of extracellular histones in development of sepsis

目的探讨细胞外组蛋白（EH）对小鼠肠黏膜屏障的影响及在脓毒症发生发展中的作用。方法选择雄性野生型C57BL／6小鼠20只，按随机数字表法分为实验组和对照组，每组10只。实验组将EH按50mg／kg经尾静脉注射人小鼠体内，对照组给予尾静脉注射等量等渗盐水。3h后分别采集两组血液标本和肠组织标本，光镜及透射电镜下对两组肠黏膜组织形态进行观察，Westernblot检测紧密连接相关蛋白（ZO-1、Occludin、Claudin-1）的表达量，酶联免疫吸附（ELISA）法检测血浆二胺氧化酶（DAO）及脂肪酸结合蛋白（I—FABP）含量，鲎试验检测血浆中内毒素（ET）的含量。结果电镜结果显示，实验组肠上皮细胞表面微绒毛排列紊乱，部分断裂、扭曲、脱落，上皮细胞紧密连接模糊，细胞间隙增宽，与对照组比较差异明显。光镜结果显示，实验组肠壁有大量炎细胞浸润，绒毛排列不规则，黏膜及黏膜下出现水肿、出血，杯状细胞出现水肿，绒毛变钝，与对照组比较差异明显。实验组Claudin-1、Occludin、ZO-1的表达量分别为0．5877±0．0606，0．1277±0．0857，0．3933±0．0808，均较对照组的0．6772±0．0383，0．4306±0．0869，0．8128±0．0963明显降低（P〈0．05）；实验组血浆DAO含量为（1．61-4-0．20）U／ml，I—FABP为（548．5±36．8）EU／ml，ET为（0．182±0．076）EU／ml，均较对照组的（0．69±0．15）U／ml、（178．84-26．9）EU／ml、（0．091±0．029）EU／ml明显升高（P〈0．05）。结论EH对小鼠肠黏膜屏障的完整性具有明显损害作用，造成内毒素移位。

Objective To investigate the effect of extracellular histones （EH） on intestinal mucosal barrier function in mice and the correlation of EH with the pathogenesis of sepsis. Methods Twenty male C57BL/6 mice were assigned into experiment group （n = 10） and control group （n = 10） according to the random number table. Same dose （50 mg/kg） of EH and saline were administered through the caudal vein of mice in experiment and control groups respectively. Blood and intestinal samples in each group were collected 3 h after the administration. Morphology of intestinal mucosal tissue was detected by light scope and transmission electron microscope. Expressions of tight junction related proteins （ ZO-1, Occludin and Claudin-1 ） were detected by western blot. Plasma levels of diamine oxidase （DAO） and intestinal fatty aeid binding protein （I-FABP） were determined by ELISA method. Plasma level of endotoxin （ET） was determined by limulus test. experiment group showed disorganized microvilli Results Under transmission electron microscope, of intestinal epithelial cells with partially twisted,broken and lost, unclear tight junctions, and widened cellular space. Under light scope, experiment group showed substantial inflammatory cell infiltration in the intestinal wall, disorganized intestinal villi, edema and hemorrhage of mucosa and submucosa, and edematous goblet cells. Experimental versus control group showed significant reduction in levels of Claudin-1 （0. 587 7 ±0. 060 6 vs. 0. 677 2 ±0. 038 3）, Occludin （0. 127 7 ±0. 085 7 vs. 0. 430 6 ± 0. 086 9） and ZO-1 （0. 393 3 ±0.080 8 vs. 0. 812 8 ＋ 0. 096 3） （ P 〈0. 05 ）. Experimental versus control group showed significantly up-regnlated plasma levels of DAO [ （ 1.61 ±0.20） U/ml vs. （0.69 ±0. 15） U/ml], I-FABP [ （548.5 ± 36.8） EU/ml vs. （178.8 ±26.9） EU/ml] and ET [ （0. 182 ±0.076） EU/ml vs. （0.091 ±0. 029） EU/ml] （P 〈0.05）. Conclusion EH can obviously impair the integrity of intestinal mucosal barrier in mice and hence induce endotoxin translocation.