肠胶质细胞网络改变在肠易激综合征外周致敏发生机制中作用的研究

Newly discovered excessive brain-derived neurotrophic factor (BDNF) released from intestinal epithelial cells contributes to abdominal pain in irritable bowel syndrome (IBS), however, the exact mechanism is unclear. The enteric glial cell (EGC) network, which connects the intestinal epithelium and the enteric nervous system, may play an important role. This study was to investigate the mechanism of peripheral sensitization which induces IBS abdominal pain at the level of BDNF-mediated EGC network alteration.①Detect EGC changes in the number, shape and BDNF pathway proteins in intestinal mucosa of IBS patients, and combined with anorectal manometry, to reveal that BDNF could induce EGC network alteration, which then participates in the occurrence of peripheral sensitization. ②Establish the animal model of visceral hypersensitivity, using BDNF knockout mice as control, to confirm the role of BDNF pathway in the EGC network alteration and its effects on visceral sensitivity in mice. ③Co-culture intestinal epithelium and EGC, as well as EGC and neuron in vitro, with intervention of BDNF pathway antagonists and EGC metabolic inhibitors, and application of the patch clamp technique, to study the impact of EGC function change on intestinal neuronal and synaptic function, and further clarify the potential mechanism of EGC network alteration in inducing enteric nervous system sensitization and the final abdominal pain. In short, our study is meaningful to elucidate the mechanism of peripheral sensitization which induces IBS abdominal pain and find a new target for IBS treatment.

新近发现肠上皮过量释放的脑源性神经营养因子(BDNF)参与肠易激综合征(IBS)腹痛的发生，但具体机制不清，连接肠上皮和肠神经系统的肠胶质细胞(EGC)网络可能在其中发挥重要作用。本研究旨在从BDNF介导EGC网络改变层面探讨诱发IBS腹痛的外周致敏机制：①检测IBS患者肠黏膜EGC数目、形态及BDNF通路蛋白的改变，结合肛门直肠测压，揭示BDNF诱导EGC网络改变并参与外周致敏的发生。②建立内脏高敏感动物模型，结合BDNF基因敲除小鼠，印证BDNF通路在EGC网络改变中的作用及对小鼠内脏敏感性的影响。③行肠上皮-EGC及EGC-神经元体外共培养，应用BDNF通路蛋白拮抗剂、EGC代谢抑制剂进行干预，结合膜片钳研究EGC功能改变对肠神经元和突触功能的影响，进一步阐明EGC网络改变致敏肠神经系统、诱发腹痛的潜在机制。本研究对阐明IBS腹痛发生的外周致敏机制，寻找IBS治疗新靶点具有深远意义。

我们前期研究发现IBS患者结肠粘膜上皮及固有层BDNF表达显著高于正常对照，并与患者腹痛程度和频率显著相关，提示肠道BDNF在IBS患者腹痛发生中可能发挥重要作用。然而，IBS患者结肠BDNF高表达的起始因素以及BDNF参与IBS腹痛发生的分子机制目前仍不清楚。本项目在此基础上运用分子生物学、电生理等方法对以上问题进一步探讨，发现肠道BDNF异常升高主要依赖于IBS患者粪便中过高的丝氨酸蛋白酶活性所导致的结肠上皮PAR-2受体的过度激活，BDNF在致敏肠伤害性感觉传入纤维的同时，还可激活整个肠胶质细胞网络，诱导肠胶质细胞释放生物活性物质，协同促进IBS内脏高敏感的发生。本研究从分子水平对肠上皮-肠胶质细胞网络在IBS中改变的研究为今后我们更深入探索人类IBS发病机制和防治策略提供了坚实的理论基础。