Neutrophil extracellular traps exacerbate endothelial tight junction dysfunction via the Wnt7a/β-catenin/HDAC5 pathway in sepsis-associated lung injury.

Sepsis is a complicated clinical disease caused by an infection-related host response, which results in acute organ dysfunction and a high mortality risk. Among the affected organs, the lungs are particularly susceptible to sepsis. Sepsis-induced acute lung injury (SI-ALI) is a common and severe complication observed among septic patients. Neutrophil extracellular traps (NETs) serve a significant role in immune and inflammatory regulation. Our previous studies have shown a close association between NETs and SI-ALI. However, the mechanism by which NETs mediate the interaction between endothelial cell (EC) barrier integrity and inflammatory responses remains incompletely understood. By reanalyzing our RNA-seq data, we discovered that NET-stimulated HUVECs had an increased cell adhesion molecules pathway, and the differentially expressed genes Wnt7a, HDAC5, and Claudin-5 were screened out. The relationships between differentially expressed genes were further established by STRING analysis. The expression levels of Claudin-5 and Wnt7a/β-catenin/HDAC5 signaling pathway proteins were evaluated by quantitative PCR (qPCR), western blotting, and immunofluorescence staining. At the same time, a cecal ligation and puncture (CLP) model was used to induce sepsis in mice to investigate the function of NETs in vivo. In our research, we demonstrated that NETs activate HDAC5 gene expression through the Wnt7a/β-catenin signaling activation, which subsequently downregulated the expression of tight junction (TJ) proteins, including Claudin-5, ZO-1, and Occludin. This led to impaired barrier function in lung microvascular endothelial cells and worsened the prognosis in a murine model of SI-ALI. Moreover, the NETs disruption and Wnt7a or HDAC5 inhibition mitigated the degradation of tight junction proteins in endothelial cells and improved outcomes in septic mice. In conclusion, our findings indicate that NETs contribute to lung endothelial barrier dysfunction via the Wnt7a/β-catenin/HDAC5 axis during the progression of SI-ALI.