Background. The gut was suggested as the driver of critical illness and organ injury. Recently, excessive formation of neutrophil extracellular traps (NETs) was associated with mucosal inflammation. Direct investigation of intestinal mucosa is essential to illuminate the potential mechanism of gut barrier in critically ill patients. We hypothesized that early enteral nutrition (EN) could decrease intestinal NETs and maintain the gut barrier. Methods. Intestinal biopsies were obtained using biopsy forceps from critically ill surgical patients complicated with enterocutaneous fistula. Expressions of tight junction (TJ) proteins, mucosal inflammation, and apoptosis were evaluated. Moreover, NET-associated proteins were evaluated in intestinal specimens of patients by Western blot and immunofluorescence analysis. Results. The intestinal barrier was significantly impaired in critically ill patients receiving early total parenteral nutrition (TPN), evidenced by intestinal villi atrophy, inflammatory infiltration, increased enterocyte apoptosis, and abnormal TJ expressions. Early EN significantly alleviated these intestinal injuries. In addition, we observed increased formation of the NET structure and elevated expressions of NET-associated proteins in intestines of critically ill surgical patients. Early EN was associated with the diminished presence of NETs and reduced expression of NET-associated proteins. Mechanically, analysis of the TLR4 pathway showed a significant increase in TLR4, NFκB, and MAPK signaling in patients receiving TPN when compared to those receiving early EN. Conclusion. The intestinal barrier is disrupted in the human gut during critical illness. Our data suggests that an increased NET structure was showed in the gut of critically ill surgical patients, and early EN treatment was associated with the reduction of NET formation and the preservation of mucosal immunity.

中文翻译：

---

早期肠内营养通过减少危重手术患者中性粒细胞胞外陷阱 (NETs) 的形成来保护肠道屏障功能

背景。肠道被认为是危重疾病和器官损伤的驱动因素。最近，中性粒细胞胞外陷阱 (NETs) 的过度形成与黏膜炎症有关。直接研究肠黏膜对于阐明危重患者肠道屏障的潜在机制至关重要。我们假设早期肠内营养 (EN) 可以减少肠道 NETs 并维持肠道屏障。方法. 使用活检钳从合并肠皮瘘的危重手术患者中获得肠道活检。评估了紧密连接 (TJ) 蛋白、粘膜炎症和细胞凋亡的表达。此外，通过蛋白质印迹和免疫荧光分析在患者的肠道标本中评估了 NET 相关蛋白。结果. 接受早期全胃肠外营养（TPN）的危重患者肠道屏障明显受损，表现为肠绒毛萎缩、炎症浸润、肠细胞凋亡增加和TJ表达异常。早期 EN 显着减轻了这些肠道损伤。此外，我们观察到重症手术患者肠道中 NET 结构的形成增加和 NET 相关蛋白的表达升高。早期 EN 与 NET 的存在减少和 NET 相关蛋白的表达减少有关。机械地，对 TLR4 通路的分析显示，与接受早期 EN 的患者相比，接受 TPN 的患者的 TLR4、NF κ B 和 MAPK 信号传导显着增加。结论. 在危重疾病期间，肠道屏障在人体肠道中被破坏。我们的数据表明，危重手术患者的肠道中显示出增加的 NET 结构，早期 EN 治疗与 NET 形成的减少和黏膜免疫的保持有关。