Novel approach to control ischemia-reperfusion injury in small intestinal transplantation

小肠是最易缺血的器官之一，缺血再灌注损伤是小肠移植的严重限制因素。本实验采用大鼠小肠缺血再灌注损伤模型，证实在大鼠小肠缺血再灌注损伤中产生TNF-α和IL-1β，特异性TNF-α和IL-1β抑制剂可减少TNF-α和IL-1β的产生，减轻肠损伤。近年来，随着TNF-α和IL-1β上游信号转导机制的研究报道，丝裂原活化蛋白激酶（mitogen-activated protein kinase，MARK）超家族受到广泛关注。尤其是c-Jun N-末端激酶（JNK）和p38通过包括缺血在内的各种刺激诱导细胞凋亡。此外，p38是产生IL-1和TNF的关键酶，提示这些酶在缺血再灌注损伤中起关键作用。本研究旨在探讨JNK和p38在大鼠小肠缺血再灌注损伤中的病理生理意义。缺血再灌注损伤小肠组织中JNK和p38蛋白表达明显增强。再灌注后肠组织的免疫组化显示，活化的p38主要位于绒毛尖端的上皮细胞中，其中存在TUNEL阳性凋亡细胞。给予JNK和p38双重抑制剂LL-Z1640-2可有效抑制这些酶的活化，减少绒毛尖端凋亡细胞的数量，从而使粘膜形态得到良好的保护。这些结果表明JNK和p38在小肠缺血再灌注损伤中起关键作用，同时抑制这些酶可能为克服小肠移植中的缺血性损伤提供新的治疗方法。

Because small intestine is one of the most susceptible organs to ischemia, ischemia-reperfusion injury is formidably limiting factor in small intestinal transplantation. By using rat small intestinal ischemia-reperfusion injury model, we demonstrated that TNF-α and IL-1β is produced in the rat small intesyinal ischemia-reperfusion injury and that the production can be reduced by the specific TNF-α and IL-1β inhibitor, attenuating the intestinal injury. Recently, mitogen-activated protein kinase (MARK) superfamily has been widely noticed as upupstream signal transduction mechanisms for TNF-α and IL-1β have been reported. Especially, c-Jun N-terminal kinase (JNK) and p38 induce cell apoptosis by various stimuli including ischemia. In addition, p38 acts as a key enzyme to produce IL-1 and TNF, suggesting these enzymes play a key role in ischemia-reperfusion Injury. In the present study, we investigated the pathophysiologic significance of JNK and p38 in rat small intestinal ischemia-reperfusion injury. Remarkable activation of JNK and p38 was shown in the injured small intestinal tissue after ischemia-reperfusion by using kinase assay. Immunohistochemistry of the intestinal tissue after reperfusion revealed that the activated p38 was mainly located in the epithelial cells of the villus tip, where TUNNEL positive apoptotic cells were present. Administration of LL-Z1640-2, a dual inhibitor of JNK and p38, effectively suppressed the activation of these enzymes, and reduced the number of apoptotic cells on villus tip, resulting that the mucosal morphology was well preserved. These results indicate that JNK and p38 play a key role in small intestinal ischemia-reperfusion injury, and that the simultaneous inhibition of these enzymes may provide a novel therapeutic approach to overcome ischemic damage in small intestinal transplantation.