脓毒症大鼠肠黏膜免疫屏障功能的变化

Alteration of immunological barrier of intestine mucosa in rats with sepsis

摘 要：目的 研究脓毒症对大鼠肠黏膜免疫屏障功能的影响.方法 60只SD大鼠随机（随机数字法）分为对照组（n=15）和脓毒症组（n=45）,采用盲肠结扎穿孔术（CLP）建立脓毒症模型.模型建立后3 h、6 h和12 h留取回肠黏膜和全血标本.分别进行肠黏膜形态学观察、肠防御素5（RD-5）及肠三叶因子3（TFF_3）Mrna表达水平检测、肠黏膜淋巴细胞凋亡分析,以及外周血中肠源性细菌DNA定性检测.结果 CLP所致脓毒症导致大鼠回肠黏膜明显损害,主要表现为上皮脱落、固有层分离、毛细血管出血和溃疡形成;脓毒症组模型建立后3 h即出现RD-5和TFF_3 Mrna表达显著性减少（与正常组比较,P〈0.05）,且6 h和12 h组进行下降（与3 h组比较,P〈0.05）,肠黏膜淋巴细胞凋亡数亦显著增加（P〈0.05）;同时,脓毒症组全血肠源性细菌DNA扩增全部阳性.结论 脓毒症时大鼠肠黏膜免疫屏障功能显著减退,且随脓毒症的发展而进行性恶化.

Abstract：Objective To investigate immunological dysfunction of intestine mucosa barrier in a rat model of sepsis. Method Sixty Sprague-Dawley rats were assigned randomly（random number） into sepsis group （n = 45）and control group （n = 15）. The animals in sepsis group were subjected to cecal ligation and puncture （CLP）, whereas rats of control group underwent a sham surgery. The ileac mucosa and segments were harvested 3 h, 6 h and 12 hours after CLP, and the blood samples were collected. Pathological changes, protein levels of defensin-5 （RD-5） and trefoil factor-3（TFF_3） mRNA, lymphocytes apoptosis in the intestinal mucosa were determined. In an additional experiment, the gut-origin bacterial DNA in blood was detected. Results In the septic animals, in-testinal mucosa showed marked injury with loss of ileal villi, desquamation of epithelium, detachment of the lamina propria, hemorrhage and ulceration. Compared with control, the expression of TFF_3 mRNA and level of RD-5 pro-tein were decreased and the mucosal lymphocyte apoptosis increased （P 〈 0.05） in sepsis group. Compared with control group, the significant differences in RD-5 and TFF_3 mRNA appeared 3 hours after CLP and those differ-ences were progressively increased in 6 hours and 12 hours after CLP in sepsis group （P 〈 0.05, F of RD-5 = 11. 76, F of TFF_3 = 16.86 and F of apoptosis = 122.52）. In addition, the gut-origin bacterial DNA in plasma de-tected was positive in all sepsis animals. Conclusions It suggests that immunological function of intestinal mucosa is impaired in septic rats and further worsened following the course of sepsis.