肿瘤坏死因子mRNA在严重烫伤大鼠小肠中的表达及细胞定位的研究

为探讨严重烫伤后肿瘤坏死因子（ＴＮＦ）在大鼠小肠中的表达及细胞定位，应用斑点杂交及原位杂交方法，结合血浆ＴＮＦ、内毒素浓度的变化，探讨了ＴＮＦｍＲＮＡ的表达及细胞定位规律。结果发现，烧伤后小肠ＴＮＦｍＲＮＡ的表达量迅速升高，在伤后６小时达峰值，是正常值的５．５６倍。门静脉血浆ＴＮＦ、内毒素的变化与之类似。正常大鼠小肠有少量的细胞表达ＴＮＦｍＲＮＡ，主要是小肠固有层内的单核吞噬细胞。烧伤后固有层内的阳性细胞明显增多，而且固有层毛细管内皮细胞表达也是阳性，隐窝内也出现大量的阳性细胞。提示：ＴＮＦ的表达分泌，在烧伤早期与肠源性内毒素血症有非常密切的联系。固有层及粘膜下层间质中的内皮细胞及单核吞噬细胞是肠道分泌ＴＮＦ的主要细胞。ＴＮＦ分泌量明显增加，其结果是造成小肠局部微循环障碍或诱导自由基的产生，从而导致肠粘膜屏障的破坏。

A study of the expression and localization of tumor necrosis factor mRNA in small intestine of rats after severe burn

In this study, the dot blotting and in situ hybridization, collaborated with determination of contents of endotoxin and TNF in plasma, were used to study the expression and localization of TNF mRNA in the intestine. The results showed that, the expression of TNF mRNA in the small intestine increased rapiAly and reached maximum at 6h postburn, being 5. 56 times higher than that of normal control. The TNF mRNA-producing cells in normal animal were mononuclear phagocytes located in lamina propria. After burn, the number of positive cells in lamina propria increased significantly, and the TNF gene-expressing cells were vascular endothelium. Many positive cells were found in the crypts of the intestine. It suggested that the expression of TNF correlated well with bacterial translocation in the early stage of burn. The mononuclear phagocytes and endothelial cells located in lamina propria and interstitial tissue were the chief TNF mRNA-producing cells in the intestine. The overproduction of TNF could provoke microvascular injury or induce the production of oxygen free radical to damage the gut mucosal barrier.