Department of Emergency and Critical Care Medicine, Shanghai Changzheng Hospital, Naval Medical University, Shanghai, 200003, People's Republic of China.
Emergency Department, Baoshan Branch of Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, 200444, People's Republic of China.
Eur J Med Res. 2024 Jun 27;29(1):349. doi: 10.1186/s40001-024-01894-5.
Sepsis is one of the most common clinical diseases, which is characterized by a serious and uncontrollable inflammatory response. LPS-induced inflammation is a critical pathological event in sepsis, but the underlying mechanism has not yet been fully elucidated.
The animal model was established for two batches. In the first batch of experiments, Adult C57BL/6J mice were randomly divided into control group and LPS (5 mg/kg, i.p.)group . In the second batch of experiments, mice were randomly divided into control group, LPS group, and LPS+VX765(10 mg/kg, i.p., an inhibitor of NLRP3 inflammasome) group. After 24 hours, mice were anesthetized with isoflurane, blood and intestinal tissue were collected for tissue immunohistochemistry, Western blot analysis and ELISA assays.
The C57BL/6J mice injected with LPS for twenty-four hours could exhibit severe inflammatory reaction including an increased IL-1β, IL-18 in serum and activation of NLRP3 inflammasome in intestine. The injection of VX765 could reverse these effects induced by LPS. These results indicated that the increased level of IL-1β and IL-18 in serum induced by LPS is related to the increased intestinal permeability and activation of NLRP3 inflammasome. In the second batch of experiments, results of western blot and immunohistochemistry showed that Slit2 and Robo4 were significant decreased in intestine of LPS group, while the expression of VEGF was significant increased. Meanwhile, the protein level of tight junction protein ZO-1, occludin, and claudin-5 were significantly lower than in control group, which could also be reversed by VX765 injection.
In this study, we revealed that Slit2-Robo4 signaling pathway and tight junction in intestine may be involved in LPS-induced inflammation in mice, which may account for the molecular mechanism of sepsis.
脓毒症是最常见的临床疾病之一，其特征是严重且不可控的炎症反应。LPS 诱导的炎症是脓毒症中的一个关键病理事件，但潜在机制尚未完全阐明。
动物模型分两批建立。在第一批实验中，成年 C57BL/6J 小鼠被随机分为对照组和 LPS（5mg/kg，腹腔注射）组。在第二批实验中，小鼠被随机分为对照组、LPS 组和 LPS+VX765（10mg/kg，腹腔注射，NLRP3 炎性小体抑制剂）组。24 小时后，用异氟烷麻醉小鼠，采集血液和肠组织进行组织免疫组化、Western blot 分析和 ELISA 检测。
注射 LPS24 小时的 C57BL/6J 小鼠表现出严重的炎症反应，包括血清中 IL-1β、IL-18 增加，肠道中 NLRP3 炎性小体激活。注射 VX765 可逆转 LPS 诱导的这些作用。这些结果表明，LPS 诱导的血清中 IL-1β和 IL-18 水平升高与肠道通透性增加和 NLRP3 炎性小体激活有关。在第二批实验中，Western blot 和免疫组化结果显示，LPS 组肠组织中 Slit2 和 Robo4 表达显著降低，而 VEGF 表达显著增加。同时，紧密连接蛋白 ZO-1、occludin 和 claudin-5 的蛋白水平明显低于对照组，这也可通过注射 VX765 逆转。
本研究揭示了肠组织中 Slit2-Robo4 信号通路和紧密连接可能参与了 LPS 诱导的小鼠炎症反应，这可能解释了脓毒症的分子机制。
