大鼠小肠移植早期排斥反应中细胞凋亡与肿瘤坏死因子-α关系的研究

Correlation between Apoptosis and Tumor Necrosis Factor-α in Early Small Intestinal Allograft Rejection in Rats

背景致炎细胞因子肿瘤坏死因子(TNF)鄄α在诱导细胞凋亡中起重要作用。目的明确小肠移植早期排斥反应中存在细胞凋亡现象,探讨TNF鄄α与细胞凋亡的关系及其在凋亡发生中的作用。方法选用Sprague鄄Dawley(SD)大鼠和Wistar大鼠行异位节段小肠移植。同基因移植组SD(供体)鄄SD(受体);异基因移植组Wistar(供体)鄄SD(受体);异基因移植+环孢素A治疗组Wistar(供体)鄄SD(受体)+环孢素A每日10mg/kg。术后第1、3、5、7天,采用原位末端标记技术(TUNEL法)检测移植肠黏膜上皮凋亡细胞,夹心酶联免疫吸附测定(ELISA)检测血清TNF鄄α水平。结果同基因移植组术后排斥反应轻微,移植肠黏膜上皮凋亡细胞数无明显变化(P>0.05);异基因移植组术后凋亡细胞数随排斥反应的加重而增加(P<0.01),并显著高于同基因移植组(P<0.01);异基因移植+环孢素A治疗组凋亡细胞数亦显著高于同基因移植组(P<0.01)。同基因移植组术后血清TNF鄄α水平无明显变化(P>0.05),异基因移植组术后血清TNF鄄α水平随凋亡细胞数的增加而增高(P<0.01)。移植术后血清TNF鄄α水平随移植肠黏膜上皮细胞凋亡的轻重而变化,两者呈正相关(r=0.837,P<0.01)。结论TNF鄄α与大鼠小肠移植早期排斥反应中的细胞凋亡现象有关,并在细胞凋亡的发生中起调节作用。

Background: Tumor necrosis factor (TNF)-α is a proinflammatory cytokine, which plays an important role in the induction of apoptosis. Aims: To identify apoptosis in early small intestinal allograft rejection, and to elucidate the correlation between TNF-α and apoptosis, and the role of TNF-α in apoptosis. Methods: Heterotopic segmental small intestinal transplantation was performed in Sprague-Dawley (SD) rats and Wistar rats. Isograft group: SD (donor)-SD (recipient); allograft group: Wistar (donor)-SD (recipient); allograft + cyclosporine A group: Wistar (donor)-SD (recipient), and cyclosporine A 10 mg/kg per day was added. The grafts were harvested on the 1st, 3rd, 5th and 7th day after operation, respectively. The apoptotic cells in graft mucosal epithelium were determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) method. The serum level of TNF-α was detected by sandwich enzyme-linked immunosorbent assay (ELISA). Results: The rejection was minimal after operation, and only slight change in the number of apoptotic cells in graft mucosal epithelium was observed in the isograft group (P>0.05). The number of apoptotic cells per crypt in allograft group was paralleled with the severity of rejection (P<0.01), and being significantly higher than that in the isograft group (P<0.01). In the allograft + cyclosporine A group, the number of apoptotic cells also increased significantly as compared with that in the isograft group (P<0.01). The changes of serum level of TNF-α were insignificant in the isograft group postoperatively (P>0.05), but elevated in accordance with the increase of apoptotic cells in the allograft group (P<0.01). The serum level of TNF-α varied with the apoptotic degree of graft mucosal epithelium after transplantation, a positive correlation was found between them (r=0.837, P<0.01). Conclusions: TNF-α is positively correlated with the apoptosis phenomenon in early small intestinal allograft rejection in rats, and plays an regulatory role in apoptotic process.