Septic serum mediates inflammatory injury in human umbilical vein endothelial cells via reactive oxygen species, mitogen activated protein kinases and nuclear factor‑κB.

Sepsis‑induced blood vessel dysfunction is mainly caused by microvascular endothelial cell injury. However, the mechanism underlying sepsis‑induced endothelial cell injury remains unclear. The present study hypothesized that sepsis‑induced inflammatory injury of endothelial cells may be the first step of endothelial barrier dysfunction. Therefore, the present study aimed to uncover the mechanism underlying the inflammatory effects of sepsis. A rat model of cecal ligation and puncture‑induced sepsis was established, and septic serum was collected. Subsequently, human umbilical vein endothelial cells (HUVECs) were treated with the isolated septic or normal serum. HUVEC viability was assessed using a Cell Count Kit‑8 assay. Furthermore, transmission electron microscopy and reverse transcription‑quantitative PCR (RT‑qPCR) analysis were carried out to observe the cell morphology and determine the mRNA expression levels in septic serum‑induced HUVECs. The protein expression levels were evaluated by western blot analysis, and the secretion of the inflammatory factors interleukin (IL)‑1β, IL‑6 and tumor necrosis factor (TNF)‑α was determined by ELISA. Additionally, reactive oxygen species (ROS) generation and nuclear factor (NF)‑κB nuclear translocation were observed under a fluorescence microscope. The results of the present study demonstrated that HUVEC viability was significantly decreased following 12‑ or 24‑h treatment with septic serum. In addition, chromatin condensation, mitochondrial vacuolization and endoplasmic reticulum degranulation were observed following treatment with septic serum. Furthermore, the secretion levels of IL‑1β, IL‑6 and TNF‑α were increased in septic serum‑stimulated HUVECs. Septic serum treatment also enhanced superoxide anion generation, promoted extracellular signal regulated kinase 1/2 (ERK1/2), N‑terminal kinase (JNK) and p38 mitogen‑activated protein kinase (p38) phosphorylation, and increased NF‑κB levels in the nuclei of HUVECs. Finally, pre‑treatment of HUVECs with the antioxidant N‑acetylcysteine, the ERK1/2 inhibitor PD98059, the p38 inhibitor SB203580, the JNK inhibitor SP610025 or the NF‑κB inhibitor pyrrolidine dithiocarbamate restored the septic serum‑induced IL‑1β, IL‑6 and TNF‑α expression. In conclusion, the results of the current study suggested that the septic serum‑induced endothelial cell injury may be mediated by increasing ROS generation, activation of mitogen‑activated protein kinases and NF‑κB translocation.