肠源性脓毒症大鼠肠系膜淋巴结免疫状态变化规律

Variation of Immune State in Mesenteric Lymph Node in Gut-derived Deptic Rats

目的：探讨肠系膜淋巴结（MLN）在腹腔感染状态下的免疫功能变化规律及产生机制。方法雄性Wistar大鼠80只．体重200—250g．随机分为假手术组（S组）和盲肠结扎穿孔组（CLP组）．每组40只。分别于CLP后6h（T1），12h（T2）．24h（T3）、72h（T4）（每个时点10只大鼠）留取腹主动脉血和MLN组织，鲎试剂偶氮显色法测定血浆内毒素水平．运用流式细胞仪测定MLN中 Th1／Th2比值和调节性T细胞（Treg）占CD4＋T细胞比例。结果：与S组比较。CLP组血浆内毒素水平在T2．T3和T4时升高．T3时达峰值（P〈0.01）；与S组比较．CLP组MLN Th1／Th2比值在T1时升高．T2．T3和T4时降低（P〈0．05或P〈0.01），CLP组MLN Treg比例在T3时降低．在T2、T3和T4时升高（P〈0．05）；与T1时比较．CLP组MLN细胞Th1／Th2比值在T2，T3和T4时降低（P〈0.05或P〈0．01）．CLP组MLN细胞Treg比例在T2，T3和T4时升高（P〈0.05或P〈0.01）。大鼠MLN的Th1／Th2比值与Treg比例呈线性负相关（r=-0．871，P〈0．05）。结论：腹腔感染状态下．MLN细胞免疫功能受到抑制。表现为Th1／Th2比值减少，导致经肠道淋巴途径移位的肠源性内毒素清除减少，引发了肠源性内毒素血症的形成。其机制可能与肠源性内毒素介导MLN Treg比例增加有关。

Objective： To investigate the variation of immune state in mesenteric lymphoid node （MLN） during gut-derived sepsis in rats. Methods： Eidhty male Wistar rats weighing 200-250g were used in this study. Intra-abdominal infection was induced by cecum ligation and puncture （CLP）. The animals were randomly divided into 2 groups： sham operation group （group S） and group CLP. Each ten rats were killed after collection of blood and MLN samples at 6h （T1）, 12h （T2）, 24h （T3） and 72h （T4,） after CLP. Plasma concentrations of endotoxin were detected, the ratio of T helper cells 1/T helper cells 2 （Th1/Th2） and the percentage of regulatory T cells （Treg） in CD4＋ T cells in MLN were determined by means of flow cytometry. Results： The levels of endotoxin were significantly higher at T2, T3 and T4 in group CLP than those in group S respectively （P〈0.01）. The ratios of Th1/Th2 were significantly higher at T1 and lower at T2, T3 and T4 in group CLP as compared with group S （P〈0.05 or P〈0.01）, while the percentages of Treg in CD4＋ T cells were significantly higher at T1 and lower at T2, T3 and T4 in group CLP as compared with group S （P〈0.05 or P〈0.01 ）. There was a negative correlation between the ratio of Th1/Th2 and the percentage of Treg （r=0.871, P〈0.05）. Conclusion： Cellular immune function in MLN is suppressed during intra-abdominal infection by the mechanism of increased percentage of Treg, which leads to gut-dedved endotoxemia.