基于p38MAPK信号通路探讨大鼠肠系膜淋巴途径在大肠腑实证所致肺损伤的作用

The pathway of "diseases from bowel to pulmonary" is the hot and difficult problem in the theory of "the lung and the large intestine being interior-exteriorly related". Our previous work showed that the mesenteric lymph duct ligation could reduce the early lung injury induced by "Syndrome of Intestinal Heat and Bowel Excess" in rats. The results suggested that the mesenteric lymph pathway is the main way of "diseases from bowel to pulmonary". The aim of this study is to investigate the mechanism of mesenteric lymph system in rats with lung injury induced by "Syndrome of Intestinal Heat and Bowel Excess" based on p38MAPK signal pathway using pathology,ELISA,real-time PCR and Western blot methods in vitro and in vivo,observe the expression and activation of p38 MAPK in lung tissue and intestinal lymph in rats with lung injury induced by "Syndrome of Intestinal Heat and Bowel Excess" and in pulmonary micro-vascular endothelial cells of rats, confirm that the intestinal lymph in "Syndrome of Intestinal Heat and Bowel Excess"is a major source of lung injury and p38MAPK signal pathway have relation to lung injury induced by "Syndrome of Intestinal Heat and Bowel Excess", and then provide a theoretical basis to explore the molecular mechanisms of lung injury induced by "Syndrome of Intestinal Heat and Bowel Excess".

"肠病及肺"的途径问题是近年研究"肺与大肠相表里"理论的热点和难点。我们前期工作表明肠系膜淋巴管结扎可减轻大鼠大肠腑实证模型早期所导致肺损伤的程度，提示肠系膜淋巴途径是"肠病及肺"的主要途径。本研究在此基础上基于p38MAPK信号通路，用病理学、ELISA、实时荧光定量PCR和Westernblot等方法分别从体外和体内两方面对大鼠肠系膜淋巴途径在大肠腑实证所致肺损伤的作用机制进行研究，观察在大肠腑实证导致肺损伤时，p38 MAPK信号通路在大鼠肺组织、肠淋巴液和体外培养的肺微血管内皮细胞中的表达和激活情况，证实大肠腑实证大鼠肠淋巴液是导致肺损伤的主要来源之一，p38 MAPK信号通路与大鼠肠系膜淋巴途径在大肠腑实证所致的肺损伤有关，从而为最终阐明大肠腑实证所致肺损伤的分子机制提供理论依据。

“肠病及肺”的途径问题是研究“肺与大肠相表里”理论的重要组成部分，也是研究的热点问题之一。本项目应用无创伤小血管夹夹闭大鼠肠系膜上动脉1 h、再灌注2 h 制备大肠腑实证动物模型，分别检测大鼠肠系膜淋巴管结扎和引流对大肠腑实证所致肺损伤和P38MAPK 信号通路的影响，分析大肠腑实证模型大鼠肠系膜淋巴液中LPS、TNFα、IL- 6 含量、淋巴液细胞分类和P38MAPK 信号通路表达和活化的变化。结果表明（1）阻断肠系膜淋巴管回流（结扎或引流）能减少大肠腑实证模型大鼠肺组织炎性细胞因子TNF-α、IL- 6释放，减轻肺组织中性粒细胞集聚造成的病理损伤，从而减轻肺损伤，这一结果可能与抑制肺组织p38MAPK信号通路有关；但肠系膜淋巴管结扎在减轻肺组织中性粒细胞浸润和病理损伤的同时，却加重了回肠中性粒细胞浸润和病理损伤；而肠系膜淋巴管结扎并引流能同时减轻肺和回肠组织中性粒细胞浸润和病理损伤。（2）大肠腑实证模型大鼠肠系膜淋巴液中性粒细胞比例升高，巨噬细胞和淋巴细胞比例降低，LPS含量升高、TLR4表达升高， p38 MAPK表达和活性均升高，其下游靶基因TNFα、IL- 6分泌增加。这一结果提示大肠腑实证大鼠肠系膜淋巴液可能是导致肺损伤的细胞因子的最早和最初来源，p38 MAPK信号通路在肠淋巴液中也就是说在到达肺脏之前的淋巴途径中已被激活。