烫伤大鼠肠内毒素移位对淋巴细胞凋亡的影响

目的 探讨烫伤大鼠脾脏和肠系膜淋巴结（mesenteric lymph nodes,MLNs)淋巴细胞凋亡与肠道LPS移位的关系。方法 30％TBSAⅢ度烫伤Wistar大鼠及对照组，取门、腔静脉血用鲎基质显色法定量LPS；脾脏和MLNs切片以TUNEL－POD法染色，应用Cooldccd成象系统、Spot和IPP（Imagine proplus)4.10a软件进行凋亡细胞计数和透射光光密度分析。结果 烫伤后大鼠门、腔静脉血LPS水平显增加（P＜0．01），伤后6h达峰值；门静脉LPS 3－48h显高于腔静脉（P＜0．01）。TUNEL－POD染色结果，MLNs伤前几乎未见凋亡淋巴细胞，但伤后显增多（P＜0．01），以3h为明显；脾脏伤前凋亡淋巴细胞多集中在皮质，伤后显减少（P＜0．01），24h后略有恢复。透射光光密度值分析表明，伤后24h内脾脏凋亡淋巴细胞的光密度值较伤前明显降低（P＜0．01）；伤后48h内MLNs凋亡淋巴细胞光密度值较伤前显增高（P＜0．01）。结论 大鼠严重烫伤早期即发生肠源性LPS血症；肠道移位LPS可诱导MLNs淋巴细胞大量凋亡，脾脏中凋亡淋巴细胞数量显减少，提示大鼠严重烫伤后可能存在脾脏免疫功能异常。

The effects of gut - origin lipopolysaccharide translocation on the apoptosis of lymphocytes in scalded rats

OBJECTIVE: To investigate the relationship between lymphocyte apoptosis in spleen and mesenteric lymph nodes (MLNs) and gut -- origin lipopolysaccharide (LPS) translocation after severe scalding in rats. METHODS: Wistar rats inflicted 30% TBSA III degree scalding were employed as the model. Serum LPS levels in portal vein and vena cava were determined by limulus amebocyte lysate (LAL) test. Apoptotic lymphocytes in paraffin -- embedded spleen and MLNs sections were detected with TdT -- mediated and dUTP nick end labeling (TUNEL) and peroxidase (POD) staining. The images were taken by cooldccd camera system, and the count and optical density (OD) value of apoptotic lymphocytes were analyzed with software Spot and Imagine proplus 4.10a (IPP4.10a). RESULTS: Serum LPS levels in portal vein and vena cava increased sharply in rats postburn (P < 0.01) and reached a peak value at 6 postburn hour (PBH). LPS level in portal vein was higher than that in vena cava (P < 0.01) in the period of 3 to 48 PBHs. The results of TUNEL -- POD staining and the count of apoptotic lymphocytes showed that the apoptotic cells were few in normal MLNs, but increased obviously postburn (P < 0.01), especially at 3 PBH. On the contrary, apoptotic lymphocytes were concentrated in spleen cortex before injury and decreased obviously postburn (P < 0.01), though a slight recovery was found after 24 PBH. Optical density of apoptotic lymphocytes was significantly reduced in spleen at 24 PBH, But the OD value of apoptotic lymphocytes in MLNs increased significantly within 48 PBHs when compared with that before injury (P < 0.01). CONCLUSION: Gut -- origin endotoxemia in rat could occur in early postburn period. The LPS translocation might induce lymphocyte apoptosis in MLNs. The decreased apoptotic lymphocytes in spleen implied abnormal immune function in spleen.