Targeting Macrophage Extracellular Traps to Disrupt Encapsulating Peritoneal Sclerosis Formation

Background: As the most serious complication of peritoneal dialysis, encapsulating peritoneal sclerosis (EPS) poses a significant threat to the life safety of peritoneal dialysis patients. However, the mechanism of peritoneum adhesion formation in EPS remains unclear. This study aims to dissect the peritoneal environment characteristics of EPS at the single-cell level, and explore the mechanism of EPS. Methods: Peritoneums of EPS patients were collected for scRNA-seq, 10x visuim spatial sequencing, electron microscopy and immunofluorescence were used to identify macrophage extracellular traps (METs), gene knockout and drug intervention were conducted to verify the pathogenic role of METs, then fluorescent tracking was utilized to observe the "netting" function of METs, and primary fibroblasts stimulated by METs were collected for RNA-seq to explore the mechanism of METs-induced fibroblast activation. Results: Spatial and scRNA-seq analysis revealed a remarkable increase of macrophages and myofibroblasts infiltrations in EPS peritoneum, and their interaction increased. Pro-inflammatory macrophages amplified in EPS group, and this subtype enriched in the extracellular trap formation pathway. The concentration of METs correlated with EPS severity, while gene knockout of PAD4 and treatment of DNase I significantly ameliorated METs formation, reducing adhesions. Mechanistically, cells adhered to the METs and aggregate into clusters. METs also induce fibroblast activation through ILK/Rac1 and p38/MAPK pathway, promoting and peritoneal adhesion. Conclusion: METs contribute to the progression of EPS by promoting fibroblast activation via ILK/Rac1 and p38/MAPK pathway and serving as scaffolds for cell aggregation, thus enhancing peritoneal thickening and adhesion. Targeting METs may offer a novel therapeutic strategy for EPS.